README: run straight from the public URL (nix run git+https://...), clone optional

Public repo: .#loop fetches over public HTTPS, README for outsiders
- flake.nix: .#loop runs git+https://gitea.surma.technology/surma/sausage (SAUSAGE_FLAKE overrides it); drop loop-internal / --internal (LAN SSH). - README: clone step, LLM token requirement, loop URL and SAUSAGE_FLAKE. - ci.yml: comment without internal host name.
2026-10-16 20:55:39 +00:00 · 2026-10-16 20:40:26 +00:00 · 2026-10-16 11:48:50 +00:00 · 2026-10-16 11:14:09 +00:00 · 2026-10-16 01:25:11 +00:00 · 2026-10-16 00:44:55 +00:00
61 changed files with 5440 additions and 2766 deletions
@@ -0,0 +1,11 @@
 # Runs on a self-hosted Nix runner (label `nixos`, host executor).
 name: ci
 on: [push, pull_request]
 jobs:
  check:
    runs-on: nixos
    steps:
      - uses: actions/checkout@v4
      - name: nix flake check
        run: nix flake check -L --show-trace
@@ -0,0 +1,45 @@
 # Working on Sausage
 Sausage is meant to be read and changed by agents, including its own agent.
 Keep it that way.
 ## Priorities
 1. **Correct.** Every behavior in `PROTOCOL.md` has a test in `cli/tests/`.
 2. **Simple and short.** Prefer the obvious code. No abstraction for one
   caller. No configuration that nobody asked for.
 3. **Readable.** A new reader must understand a file without the others.
   Each module starts with a doc comment that says what it owns.
 4. **Efficient** on the paths that run per message.
 5. **Raw and minimal.** Sausage has no permissions, sandboxing beyond WASI,
   limits, or authentication. Do not add them to the core. Add nothing to
   the host that an actor (or the agent, by changing itself) could do.
 ## Layout
 - `cli/`: the host (`sausage` binary and library).
  - `lib.rs`: `Host`, which starts and stops a world.
  - `broker.rs`: routing, mailboxes, the version store, broker requests.
  - `supervisor.rs`: runs one WASM actor (restarts, swaps, rollbacks).
  - `runtime.rs`: Wasmtime instances and what they get (mounts, network).
  - `candidate.rs`: tests a new version. `cargo_actor.rs`: builds Rust.
  - `world.rs`: the on-disk layout. `console.rs`: the terminal.
 - `sdk/`: `sausage-actor`, the SDK for Rust actors. Never published: the
  `cargo` actor points `sausage-actor = "0.1"` at its local copy.
 - `agent/`: the agent actor. `sausage init` embeds and builds it.
 - `examples/`: small actors. They are not workspace members.
 - `PROTOCOL.md`: the contract between the host and the actors. Change it in
  the same commit as the behavior. `DECISIONS.md` says why; when the two
  disagree, `PROTOCOL.md` and the code win.
 ## Checks
 ```sh
 nix flake check -L      # all tests below; CI runs this on every push
 nix develop -c cargo test -p sausage -p sausage-actor -p agent
 nix develop -c cargo build --release -p agent --target wasm32-wasip2
 nix develop -c cargo clippy --workspace
 ```
 `nix run -- init` and `nix run -- run` must keep working without other
 setup.
@@ -15,7 +15,7 @@ dependencies = [
 name = "agent"
 version = "0.1.0"
 dependencies = [
- "async-channel",
+ "sausage-actor",
 "serde",
 "serde_json",
 "wstd",
@@ -1593,11 +1593,22 @@ dependencies = [
 "serde",
 "serde_json",
 "tokio",
 "toml_edit",
 "wasmtime",
 "wasmtime-wasi",
 "wasmtime-wasi-http",
 ]
 [[package]]
 name = "sausage-actor"
 version = "0.1.0"
 dependencies = [
 "async-channel",
 "serde",
 "serde_json",
 "wstd",
 ]
 [[package]]
 name = "scopeguard"
 version = "1.2.0"
@@ -1929,6 +1940,19 @@ dependencies = [
 "serde_core",
 ]
 [[package]]
 name = "toml_edit"
 version = "0.25.17+spec-1.1.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "e3641d5bbb5349a79e1020a242d251efbc546ad8048d133958323ce9c40a9c9c"
 dependencies = [
 "indexmap",
 "toml_datetime",
 "toml_parser",
 "toml_writer",
 "winnow",
 ]
 [[package]]
 name = "toml_parser"
 version = "1.1.5+spec-1.1.0"
@@ -2791,6 +2815,9 @@ name = "winnow"
 version = "1.0.4"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "23b97319f7b8343df12cc98938e5c3eb436064524c8d2b4e30a1d3a36eecdf81"
 dependencies = [
 "memchr",
 ]
 [[package]]
 name = "winx"
@@ -1,5 +1,10 @@
 [workspace]
 resolver = "3"
-members = ["cli", "agent"]
+members = ["cli", "agent", "sdk"]
 default-members = ["cli"]
 exclude = ["examples"]
 # Wasmtime compiles components with Cranelift. Optimize dependencies in dev
 # builds, so that tests and debug runs start actors quickly.
 [profile.dev.package."*"]
 opt-level = 2
@@ -1,154 +1,55 @@
 # Decisions
-This file lists the design decisions of the spike. **(you)** marks a decision
+Why Sausage is the way it is. `PROTOCOL.md` and the code own the details;
-that Surma made. **(spike)** marks a decision that Scout made alone during the
+when this file disagrees with them, they win.
 night and that needs review.
-## Architecture
+## The shape
- **(you)** Actors are WASI commands (`wasm32-wasip2`). They use stdin, stdout,
+- **Actors are WASI commands, not components with interfaces.** stdin,
-  files, and HTTP. No WIT interfaces, no component composition.
+  stdout, files, HTTP, and sockets are enough, and every language can do
- **(you)** Actors exchange newline-delimited JSON through the host, which is
+  them.
-  the broker. No built-in request/response. A reply is a message with
+- **Messages are JSON lines through a broker, fire and forget.** Like
-  `reply_to`. Delivery is at most once.
+  Erlang: no acknowledgments, no request/response. A reply is a message with
- **(you)** The broker accepts only `.wasm` files. It knows no source language.
+  `reply_to`. Sausage is not a reliable message bus.
- **(you)** `cargo` is a built-in Rust compiler actor. **(spike)** It is native
+- **The broker accepts only `.wasm` files.** It knows no source language.
-  (host code), because cargo cannot run inside WASM.
+  `cargo` is one compiler actor; others can add more languages.
- **(you)** The agent is a normal WASM actor with the fixed ID `agent`. It can
+- **The world folder is the source of truth.** Everything about an actor is
-  read and upgrade its own source.
+  in `actor/<id>/`. Copy a folder into another world, and it runs there.
- **(spike)** Three native actors: `broker`, `console`, `cargo`.
+- **The agent is a normal WASM actor.** It can read and upgrade its own
- **(you)** One Cargo workspace with two crates: `cli` (binary `sausage`) and
+  source, and change how it does inference.
  `agent`. **(spike)** Example actors are in `examples/`, outside the workspace.
 - **(you)** `sausage init` builds the agent and asks for the API shape, the
  endpoint, the model, and the token. **(spike)** The token can also come from
  `SAUSAGE_API_TOKEN`. The source contains no endpoint and no token.
-## Messages
+## Minimal on purpose
- **(spike)** Stdin line: `{"id", "from", "reply_to"?, "body"}`.
+The harness does only what it needs to keep going. Everything else can be an
-  Stdout line: `{"to"?, "id"?, "reply_to"?, "body"}`.
+actor, or a change that the agent makes to itself.
 - **(spike)** The broker sets `from`. An actor can choose its own `id`. The
  broker then uses `"<sender>/<id>"`, so IDs cannot collide or be faked.
  Without an `id`, the broker assigns `m-<n>`.
 - **(you)** Without `to`, a message goes to the subscribers of the sender.
  **(spike)** `subscribe` / `unsubscribe` messages to the broker. The registry
  stores subscriptions, so they survive restarts and upgrades. `init`
  subscribes `console` to `agent`.
 - **(spike)** Errors from routing come back as
  `{"type": "undeliverable", "reason", "to"}` from `broker`.
 - **(spike)** Lifecycle: `{"type": "shutdown"}` from `broker`, then EOF on stdin.
  After 5 seconds the broker kills the instance.
 - **(spike)** Lines on stdout that are not JSON objects with `body` go to the
  actor's `stderr.log` with a note.
-## Filesystem
+- **The host is not self-modifiable; actors are.** So the host keeps only
  what an actor cannot do for itself: routing, running instances, versions,
  tests before an install, and the rollback of a version that crash-loops.
  Without that rollback, a broken self-upgrade would end the agent.
 - **No permissions, no limits, no hiding.** Any actor can message, upgrade,
  or stop any actor, read every folder, and use the network. People who want rules
  can build them.
 - **No re-delivery and no state snapshots.** A crash loses the message, and
  all versions of an actor share `data/` and `public/`. A rollback restores
  code, not data.
 - **The agent is dumb.** It has a short prompt, a few tools, an append-only
  history that it sends in full, and no compaction. When the context is too
  large, it stops sending the oldest turns, so it never gets stuck.
- **(you)** `/data` private, `/public` own public files,
+## Small choices
  `/actor/<id>/public` and `/actor/<id>/source` read-only for everyone.
 - **(spike)** The broker also writes `/actor/<id>/status.json` and
  `/actor/<id>/stderr.log`. `ls /actor` is the registry.
 - **(you)** Commit on close: a write becomes visible only when the writer
  closes the file. **(spike)** This also applies to `/data`. Implementation: a
  wrapper around the `wasmtime-wasi` filesystem. An open for write goes to a
  hidden `.sausage-tmp-*` file next to the target. The descriptor drop renames
  it into place. Details:
  - A normal exit commits every open file (process exit closes files).
  - A trap or kill discards uncommitted writes.
  - An append or an edit without truncate copies the old content first.
  - Other descriptors see the old content until the close.
  - Directory operations take effect immediately.
  - The layer hides `.sausage-tmp-*` names from listings, `stat`, `open`,
    `rename`, and `unlink`.
  - Symlinks are disabled (they would break the path tracking).
  - No `fsync`. A power loss can lose committed data.
 - **(spike)** Raw sockets are not available (no network permission), but the
  `wasi:sockets` interfaces are linked, so programs that import them still
  start.
-## Broker requests
+- **Plain POSIX files.** An earlier version staged every write until close.
-
+  That broke `tempfile`, git, and SQLite, which expect normal files. Atomic
- **(spike)** `spawn`, `upgrade`, `rollback`, `stop`, `start`, `remove`,
+  publishing is the usual temporary file + `rename`.
-  `subscribe`, `unsubscribe`, `list`.
+- **Test first, then switch.** A new version is tested where it lies. Only
- **(you)** `spawn` and `upgrade` take `wasm`, plus optional `source` and
+  a version that passes goes to `versions/`, and the old one runs until
-  `built_by` metadata. **(spike)** The broker copies the `.wasm` file and the
+  then. `versions/` keeps every version that was installed, so a rollback
-  source folder into `broker/versions/<id>/<n>/`, with `meta.json` (paths,
+  can always go back. A file that fails stays where it was put.
-  builder, requester, time).
+- **Tests are JSON transcripts** next to the source. They run on a copy of
- **(spike)** Path resolution: `/actor/...` is global, and `/public/...` and
+  the actor's state, without network, so a test cannot send real requests.
-  `/data/...` belong to the sender. `..` is rejected. Native senders (the
+- **`broker` and `cargo` never answer a reply,** so no two actors answer
-  console) can give absolute host paths.
+  each other forever. The agent starts a turn only for text that is not a
- **(you)** Anyone can upgrade anyone. No permissions.
+  reply, for the same reason.
- **(spike)** Actor IDs: `a-z`, `0-9`, `-`, `_`, at most 64 characters.
+- **The SDK is not published.** `cargo` points `sausage-actor = "0.1"` at its
- **(spike)** `remove` archives every folder of the actor to `archive/`. Nothing
+  own copy, which it also shows in `/actor/cargo/public/sdk/`.
  is deleted.
 ## Upgrades, tests, rollback
 - **(spike)** The tests are message transcripts in `source/tests/*.jsonl`:
  `{"send": body}` and `{"expect": subset-of-body, "to"?}`. Each file runs in
  a fresh candidate on a copy of the actor's `/data` and `/public`. The
  candidate has no HTTP access. An `expect` waits up to 10 s. Without tests,
  the candidate must stay up for 2 s (smoke test).
 - **(spike)** Swap: hold the mailbox, stop the old instance gracefully,
  snapshot `/data` + `/public` into the old version's folder, install the new
  source in `/actor/<id>/source`, start the new instance, release the mailbox.
 - **(spike)** Restart after a crash: backoff 0.5 s × 2ⁿ, at most 30 s. The
  counter resets after 60 s of uptime.
 - **(spike)** Parked message: when an instance traps, the broker keeps the
  last delivered message. It delivers that message again after the next
  upgrade, not after a plain restart (that would loop).
 - **(spike)** Crash loop: 3 crashes within 30 s after an upgrade → automatic
  rollback to the previous version, with its data snapshot. The broker
  informs the actor that requested the upgrade.
 - **(spike)** `rollback` without `version` goes to the highest older version.
  It restores that version's snapshot, and it first snapshots the current
  state, so a roll-forward is possible.
 - **(spike)** Versions are per actor, not global.
 ## Limits
 - **(spike)** Mailbox: 1,000 messages. When it is full, the sender gets
  `undeliverable`.
 - **(spike)** The broker waits 30 s when it writes to an actor's stdin. Then it
  drops the message and logs it.
 - **(spike)** Time slices: the epoch advances every 10 ms, and each guest
  yields at each epoch.
 - **(spike)** One `sausage run` per world (file lock on `world/.lock`).
 - **(spike)** HTTP for all running actors, with no allow-list yet.
 ## Agent
 - **(you)** API shapes: OpenAI Responses and Anthropic Messages, chosen by
  `"api"` in `/data/config.json`.
 - **(spike)** Config fields: `api`, `base_url`, `model`, `token`, optional
  `reasoning_effort` and `max_tokens` (16,000). OpenAI: `POST
  {base_url}/v1/responses` with `store: false` and encrypted reasoning passed
  back. Anthropic: `POST {base_url}/v1/messages` with `x-api-key`.
 - **(spike)** One shared conversation in `/data/history.json`, in a neutral
  format, so the API shape can change. The history is limited to 600 entries,
  with the cut at a user message. There is no compaction yet.
 - **(spike)** A turn starts only for `{"type": "text"}` messages *without*
  `reply_to`. Replies never start turns, so two actors cannot keep the agent
  in an endless loop. Other messages are collected and shown at the next
  turn.
 - **(spike)** Tools: `send_message` (with optional wait for the reply),
  `wait_for_messages`, `read_file`, `list_dir`, `write_file`, `copy_dir`,
  `remove_path`. At most 40 steps per turn. Tool output is cut at 30 KB.
 - **(spike)** The final text of a turn goes to the sender, as a reply to the
  message that started the turn.
 - **(spike)** A shutdown during a turn saves the turn to `/data/turn.json`. The
  next start (for example after a self-upgrade) resumes the turn and answers
  the original message.
 ## Console
 - **(spike)** `@<actor> <json|text>`, plain text to `agent`, `/deploy`,
  `/list`, `/sleep`, `/await`, `/help`, `/quit`. `/sleep` and `/await` exist
  for scripted tests.
 ## Known risks (accepted for now)
 - Build scripts and proc macros run as native code in the host environment.
 - Any actor can upgrade the agent with code that reads the token.
 - Any actor can message, stop, upgrade, or remove any actor.
 - A full copy of `/data` and `/public` at every upgrade is slow for large data.
 - Mailboxes are in memory. A host crash loses queued messages.
@@ -0,0 +1,203 @@
 # The Sausage protocol
 This is the contract between the host and the actors. An actor in any
 language that follows it works in Sausage. The host publishes this file at
 `/actor/broker/public/PROTOCOL.md`, so every actor can read it.
 ## Actors
 An actor is a WASI 0.2 command (`wasm32-wasip2`): a program with `main`. The
 host runs one instance per actor. An instance can run forever.
 The instance gets:
 - **stdin:** one message per line, from the broker
 - **stdout:** one message per line, to the broker
 - **stderr:** free text, appended to `/actor/<id>/stderr.log`
 - **environment:** `SAUSAGE_ACTOR` (its ID), `SAUSAGE_VERSION` (its version),
  and `SAUSAGE_CANDIDATE=1` during a test run
 - **the network:** outgoing HTTP and HTTPS through `wasi:http` (the host does
  TLS), and TCP, UDP, and DNS through `wasi:sockets`, including listening on
  a port of the host
 - **the filesystem** described below
 ## Messages
 A line on **stdin**:
 ```json
 {"id": "m-17", "from": "console", "reply_to": "agent/a5", "body": {"type": "text", "text": "hi"}}
 ```
 A line on **stdout**:
 ```json
 {"to": "console", "id": "a6", "reply_to": "m-17", "body": {"type": "text", "text": "hello"}}
 ```
 - `body` is required. By convention it is an object with a `"type"`.
  Text for people is `{"type": "text", "text": "..."}`.
 - `to` is the recipient. Without `to`, the broker publishes the message to
  every subscriber of the sender.
 - `id` is an optional string. If the actor sets it, the message ID is `"<sender>/<id>"`.
  Otherwise, the broker assigns `m-<n>`. The broker always sets `from`.
 - `reply_to` marks a reply: its value is the ID of the message it answers.
  There is no request/response. A reply is a new message.
 - **Never answer a reply,** or two actors can answer each other forever.
  `broker` and `cargo` ignore messages that have a `reply_to`.
 - Messages are fire and forget: delivery is at most once. Each actor has a
  mailbox of 1,000 messages, which keeps messages while the actor restarts
  or is upgraded. If the broker cannot deliver a message, the sender gets
  `{"type": "undeliverable", "reason": "...", "to": "..."}` from `broker`.
 - An actor must keep reading stdin. If the broker must stop or upgrade an
  actor while a message waits for it to read stdin, it kills the actor.
 Before the broker stops an instance, it sends
 `{"id": "broker/shutdown", "from": "broker", "body": {"type": "shutdown"}}`
 and then closes stdin. The broker still routes what the actor writes until
 it exits. After 5 seconds, it kills the instance.
 ## Filesystem
 Each instance sees three folders:
 | Path | Access | Contents |
 | --- | --- | --- |
 | `/data` | read-write | the actor's state |
 | `/public` | read-write | the files that the actor publishes |
 | `/actor` | read-only | the `actor/` folder of the world |
 `/actor/<id>/` holds everything about an actor: `actor.wasm`, `actor.json`
 (installed version, running, subscriptions, tapped), `source/`, `public/`, `data/`,
 `stderr.log`, and `versions/<n>/`. `ls /actor` lists all actors.
 Files are plain POSIX files: a write is visible at once. To publish a file
 so that readers never see half of it, write a temporary file and `rename` it
 (the Rust SDK has `write_atomic`).
 Send large or binary data as a path under `/actor/<id>/public/`, not inside a
 message.
 ### Actor-served files: `/actor/<id>/fs/`
 Files under `/actor/<id>/fs/` are not on disk: the actor `<id>` serves them.
 Every actor can read and write them. The host turns each file operation into a
 message from `fs` to `<id>` and waits up to 10 seconds for the reply. `path`
 is relative to `fs/` and starts with `/` (the folder itself is `/`).
 | Request | Reply |
 | --- | --- |
 | `{"type": "fs_read", "path"}` | `{"type": "fs_file", "text"}` (or `"base64"` instead of `"text"`), or `{"type": "fs_dir", "entries": [{"name", "type": "file" \| "dir"}]}` |
 | `{"type": "fs_write", "path", "text"}` (or `"base64"` for non-UTF-8 data) | `{"type": "fs_done"}` |
 | `{"type": "fs_mkdir", "path"}`, `{"type": "fs_remove", "path"}` | `{"type": "fs_done"}` |
 | `{"type": "fs_rename", "path", "to"}` | `{"type": "fs_done"}` |
 Any request can be answered with `{"type": "fs_error", "errno": "no-entry"}`.
 `errno` is a `wasi:filesystem` error code: `no-entry`, `exist`,
 `not-directory`, `is-directory`, `not-empty`, `access`, `not-permitted`,
 `invalid`, `unsupported`, `busy`, or `io` (also for anything else).
 - Opening a file sends `fs_read` once. Reads come from that copy.
 - After a change, closing (or syncing) the file sends the whole file in one
  `fs_write`.
 - No reply within 10 seconds, or an actor that does not exist, makes the
  operation fail (`io`, or `no-entry`). An actor that opens its own `fs/`
  waits for itself and fails after the timeout.
 - `fs` is reserved: no actor can have that ID.
 ## The broker
 Requests to `broker`. The answer is a message whose `reply_to` is the ID of
 the request: the request's `type` in past tense (`spawned`, `upgraded`,
 `rolled_back`, `stopped`, `started`, `removed`, `subscribed`, `unsubscribed`,
 `tapping`, `untapped`, `scanned`, `exiting`), or `{"type": "error", "reason": "..."}`.
 | `type` | Fields | Effect |
 | --- | --- | --- |
 | `spawn` | `actor`, `wasm`, `source`?, `built_by`? | test, then start a new actor |
 | `upgrade` | `actor`, `wasm`, `source`?, `built_by`? | test, then swap the version |
 | `rollback` | `actor`, `version` | go back to an older version |
 | `stop`, `start` | `actor` | stop or start an actor |
 | `remove` | `actor` | stop the actor (normal shutdown), then delete its whole folder `/actor/<id>/` (all versions, `data/`, `public/`, logs); answer `{"type": "removed", "actor"}`. Messages to it are then undeliverable, and the ID can be spawned again. An unknown actor or a native one (`broker`, `console`, `cargo`, `fs`) is an `error` |
 | `subscribe`, `unsubscribe` | `actor` | receive (or not) what `actor` publishes |
 | `tap`, `untap` | | receive (or not) a copy of every message the broker routes |
 | `scan` | | boot new or changed `actor.wasm` files |
 | `exit` | | answer `exiting`, stop every actor, and end the `sausage` process (a wrapper like `nix run .#loop` starts it again, updated) |
 Paths are `/actor/...`, or the sender's `/public/...` or `/data/...`.
 **Taps.** After `tap`, the sender gets a copy of every message that the
 broker routes (direct messages, replies, and publishes, between any actors,
 including its own), for debugging, logging, or a live view of the world:
 ```json
 {"type": "tapped", "message": {"id": "m-17", "from": "console", "to": "agent", "reply_to": null, "body": {...}}, "ts": 1792132579067}
 ```
 - `to` is `null` for a publish: one copy per publish, not per subscriber.
 - `ts` is the time of routing, in milliseconds since the Unix epoch.
 - Copies come from `broker`. They are not routed themselves, so they are
  never tapped, and each message is tapped once per tapper.
 - A copy that does not fit into the tapper's mailbox is dropped; routing
  never waits for a tapper, and nobody gets `undeliverable` for a copy.
 - Never answer a copy: the answer would be tapped again, forever.
 - Like subscriptions, a tap is saved in `actor.json` (`"tapped": true`) and
  survives restarts and upgrades. `untap` ends it.
 **Versions.** A new version (from `spawn`, `upgrade`, or a changed
 `actor.wasm` on disk) is tested first, while the old version keeps running.
 Only when its tests pass does the broker copy it to `versions/<n>/`
 (`actor.wasm`, `source/`, `meta.json`) and switch to it. So `versions/` holds
 exactly the versions that were installed, and instances always run from
 there. If the tests fail, nothing changes, and the sender gets an `error`
 with the reason. All versions share the actor's `data/` and `public/`: a
 new version must read the data of the old one.
 **Tests.** The broker runs the candidate on a copy of the actor's `data/`
 and `public/`, without network. The tests are JSON files in
 `<source>/tests/*.json`, one scenario per file:
 ```json
 {
  "description": "add, then list",
  "steps": [
    {"send": {"type": "add", "text": "milk"}, "expect": {"type": "added"}},
    {"send": {"type": "list"}, "expect": [{"type": "notes"}]}
  ]
 }
 ```
 Each step sends `send` (from `from`, default `test`), then reads the next
 line that the candidate writes for each `expect` entry, in order, within 10
 seconds. An entry matches when it is a subset of the message body. With
 `to`, the message must also go to that recipient. Each file runs in a fresh
 instance. A version without test files passes.
 **Swap.** The broker holds the mailbox, stops the old instance, makes the
 top-level `actor.wasm` and `source/` a copy of the new version, and starts
 it. A rollback does the same with the older version.
 **Crashes.** The broker restarts a crashed actor after 0.5 s, then doubles
 the delay up to 30 s. A new version that crashes 3 times within 30 seconds
 after an upgrade goes back to the previous version. The actor that asked for
 the upgrade gets `{"type": "rolled_back", "from", "to", "reason", "last_exit"}`.
 **The folder is the truth.** At start, and on `scan`, the broker boots every
 `actor/<id>/actor.wasm`. If the file differs from the installed version, it
 is a new version, tested with the tests in `actor/<id>/source/`. If its
 tests fail, the file stays where it is, the reason goes to `stderr.log`, and
 the next scan tries again.
 ## The `cargo` actor
 ```json
 {"type": "build", "source": "/actor/agent/public/drafts/notes"}
 ```
 The reply is `{"type": "built", "wasm": "/actor/cargo/public/builds/<n>/<name>.wasm", "built_by": "cargo", ...}`
 or `{"type": "build_failed", "errors": "..."}`. Pass `wasm`, `source`, and
 `built_by` on to `spawn` or `upgrade`.
 A Rust actor depends on the SDK with `sausage-actor = "0.1"`. `cargo` points
 that dependency at the SDK of the host, which it publishes at
 `/actor/cargo/public/sdk/`.
@@ -2,64 +2,74 @@
 You can see how the sausage is made.
-Sausage is a system of actors that you grow by talking to it. Every actor is a
+Sausage is a world of small programs ("actors") that you grow by talking to
-WASI program (a `.wasm` file) with stdin and stdout. Actors send each other
+it. Each actor is a WASI program with stdin and stdout. Actors send each other
-newline-delimited JSON messages through a broker. The agent is an actor too:
+JSON messages, one per line, through a broker. The agent is an actor too: it
-it does inference over HTTP, writes new actors, and can change its own code.
+writes new actors in Rust, builds them, tests them, starts them, and can
 change its own code.
-Inspired by [Jiti](https://ghuntley.com/lisp/), but with WASM instead of a
+## Start
 Lisp image.
-## Quick start
+You need [Nix](https://nixos.org/download) with flakes, and an API token for
 an LLM (OpenAI Responses or Anthropic Messages API). No clone needed:
 ```sh
-nix develop
+nix run git+https://gitea.surma.technology/surma/sausage -- init   # creates ./world and builds the agent (a few minutes)
-cargo build --release
+nix run git+https://gitea.surma.technology/surma/sausage -- run    # starts the world and a console
 export SAUSAGE_API_TOKEN=...            # or type it at the prompt
 ./target/release/sausage init world --api openai-responses \
    --base-url https://api.example.com --model some-model
 ./target/release/sausage run world
 ```
-`init` builds the agent (the first build takes a few minutes) and writes its
+`init` asks for the API shape (`openai-responses` or `anthropic-messages`),
-configuration to `world/private/agent/data/config.json`. The source contains
+the base URL, the model, and the token. It reads `SAUSAGE_API`,
-no endpoint and no token.
+`SAUSAGE_BASE_URL`, `SAUSAGE_MODEL`, and `SAUSAGE_API_TOKEN` first. The
 values go to `world/actor/agent/data/config.json`. Both commands take another
 folder as an argument, for example `... -- run my-world`.
 To keep a world on the newest version, run it in a loop:
 ```sh
 nix run git+https://gitea.surma.technology/surma/sausage#loop -- my-world
 ```
 The loop runs `nix run --refresh git+https://gitea.surma.technology/surma/sausage -- run my-world`.
 When the host crashes or an actor sends `@broker {"type":"exit"}`, the loop
 fetches the newest commit and starts it again. `/quit` ends the loop. Set
 `SAUSAGE_FLAKE` to run another flake URL instead, for example your fork.
 From a clone (`git clone https://gitea.surma.technology/surma/sausage`), the
 same commands are `nix run -- init`, `nix run -- run` and `nix run .#loop`.
 In the console:
 ```text
-hello                               → text to the agent
+write an actor "notes" that stores notes, and start it   → text to the agent
@notes {"type":"add","text":"milk"}                      → a JSON message to an actor
-@agent what actors exist?           → text to an actor
+@agent hello                                             → text to an actor
 /deploy notes examples/notes        → build with cargo, then spawn or upgrade
 /list                               → list actors
 /await agent 300                    → wait for the next message (scripts)
 /quit
 ```
-## Concepts
+## The world folder
- **Actor**: a `wasi:cli/command` program. It reads messages on stdin and
+The folder is the source of truth. Every actor lives in `world/actor/<id>/`:
  writes messages on stdout. Logs go to stderr.
 - **Message**: `{"id", "from", "reply_to"?, "body"}` on stdin;
  `{"to"?, "id"?, "reply_to"?, "body"}` on stdout. No `to` = publish to
  subscribers. There is no request/response: a reply is a new message with
  `reply_to`. Delivery is at most once.
 - **Broker**: routes messages, owns mailboxes, and runs actors. It accepts
  only `.wasm` files: `spawn`, `upgrade`, `rollback`, `stop`, `start`,
  `remove`, `subscribe`, `unsubscribe`, `list`.
 - **cargo**: the built-in Rust compiler actor. `build` a source folder, get a
  `.wasm` path back. Other actors can add other languages.
 - **Filesystem** of each actor:
  - `/data`: private state
  - `/public`: its public files
  - `/actor/<id>/{public,source,status.json,stderr.log}`: every actor, read-only
-  A write becomes visible when the writer closes the file (commit on close).
+```text
- **Upgrade**: the broker tests the candidate on a copy of `/data` and
+actor.wasm     the current version
-  `/public` (transcripts in `source/tests/*.jsonl`). Then it holds new
+actor.json     installed version, running, subscriptions
-  messages, stops the old version, starts the new one, and delivers the held
+source/        the source of the current version
-  messages. A new version that crashes 3 times in 30 seconds is rolled back.
+public/        files that the actor publishes
 data/          the actor's state
 stderr.log     what the actor and the broker write about it
 versions/<n>/  every installed version: actor.wasm, source/, meta.json
 ```
-See [DECISIONS.md](DECISIONS.md) for every design decision and
+To add or replace an actor by hand, put an `actor.wasm` (and its `source/`,
-[SPIKE.md](SPIKE.md) for the spike results.
+with the tests in `source/tests/`) into its folder. Then restart the world or
 send `@broker {"type":"scan"}`. The broker tests the file before it uses it.
 If the tests fail, the old version keeps running, and `stderr.log` says why.
 ## More
 - [PROTOCOL.md](PROTOCOL.md): messages, the filesystem, the broker, `cargo`.
  Read this to write an actor in any language.
 - [`sdk/`](sdk/): `sausage-actor`, the SDK for Rust actors.
 - [`examples/notes`](examples/notes): a small actor with a test.
 - [AGENTS.md](AGENTS.md): how to work on Sausage itself.
@@ -1,107 +0,0 @@
 # Spike results
 Date: 2026-10-15. Host: Scout container (8 cores), Rust 1.99, Wasmtime 49.0.3,
 `wstd` 0.6.8. All numbers come from `sausage run` with release builds.
 ## 1. Host, broker, routing, filesystem — works
 - `sausage init` builds the agent and registers it. `sausage run` starts the
  broker, `cargo`, the console, and every registered actor.
 - Routing, replies (`reply_to`), publish to subscribers, and `undeliverable`
  errors work.
 - **Read-only:** a write to `/actor/<other>/public/...` fails with "Operation
  not permitted". A write to `/actor/<self>/public/...` fails too. A write to
  `/public/...` works.
 - **Commit on close:** while `fs-a` holds `/public/y.txt` open, `fs-b` gets
  "No such file". `fs-a` itself also gets it through a second descriptor. The
  temporary file does not appear in listings. After the close, `fs-b` reads
  the content.
 - **Append:** `append` to an existing file copies the old content. Readers
  see the old version until the close.
 - **Crash with an open file:** the write is discarded, and the old version
  stays.
 - **Escapes:** `/data/../../../../etc/hostname` and
  `/actor/../private/agent/data/config.json` fail.
 - **Hard kill of the host:** after `kill`, no `.sausage-tmp-*` files remained,
  and the next `sausage run` started every actor again.
 ## 2. Async stdin + HTTPS in one actor — works
 `examples/fetch` (`wstd`) handles `ping` at once while a 2-second HTTPS
 request runs. HTTPS and plain HTTP both work through `wasi:http`, and the host
 does TLS. Bodies go to `/public/fetch/<n>`, and the reply contains the
 global path.
 One server (`http://neverssl.com/`) never answered. `curl` also hangs on it,
 so the server is the cause. But a request without a timeout keeps its task
 alive, and the actor then did not exit on `shutdown`. The broker killed it
 after 5 s, as designed. Actors should set HTTP timeouts.
 ## 3. Upgrade cycle — works
 - **No loss during a swap:** `ticker` sent 200 messages to `notes` at 50 ms
  intervals. `notes` was upgraded from v1 to v2 during the stream. The swap
  happened after tick 68. The v1 snapshot has ticks 1–68, and v2 has ticks
  1–200, in order, with no gaps.
 - **Parked message:** `{"type":"crash"}` crashed v1. The broker restarted v1
  and kept the message. After the upgrade to v2 (which handles `crash`), the
  broker delivered it again, and v2 answered `not_crashing`.
 - **Crash loop:** an upgrade to `examples/crasher` passed the smoke test (it
  crashes after 3 s). It crashed 3 times in about 10 s. The broker rolled back
  to v2 with its data and sent `rolled_back` to the console.
 - **Explicit rollback** v2 → v1 restored the v1 snapshot.
 - **Rejections:** a compiler error comes back as `build_failed` with the
  rendered diagnostics. A failing transcript rejects the upgrade, and the old
  version keeps running. Invalid IDs and `..` paths are rejected.
 ## 4. Agent — works with both API shapes
 - **`gpt-6-luna`** (OpenAI Responses) through the vendors proxy:
  - Asked "which actors exist", it called `broker` `list` and answered in
    about 4 s (2 inferences).
  - Asked for a `counter` actor, it took these steps without help:
    1. It wrote `Cargo.toml`, `src/main.rs`, and `tests/basic.jsonl`.
    2. It built the crate with `cargo` (1.9 s).
    3. It spawned the actor (the tests passed).
    4. It sent increment, increment, get (1, 2, 2).
    5. It read `/actor/counter/public/value.txt`.
 - **Self-upgrade:** asked to change its own prompt, it took these steps:
  1. It copied its source and changed only `prompt.md` (a 3-line diff).
  2. It built the change and upgraded `agent`.
  3. The upgrade stopped it in the middle of the turn. The new version
     resumed the turn from `/data/turn.json` and answered with the new
     signature.
 - **`claude-haiku-4-5`** (Anthropic Messages): the same conversation
  continued, with tool calls.
 ## 5. Measurements
 | What | Result |
 | --- | --- |
 | Round trip actor → actor → actor | p50 88 µs, p99 172 µs |
 | Sequential round trips | ~10,400 per second |
 | Warm `cargo` build, small actor | 0.5–1.9 s |
 | Warm `cargo` build, agent | 5.5 s |
 | First build of the agent (`init`) | 17 s |
 | Component compile, small actor | ~70 ms |
 | Component compile, agent (870 KB) | ~290 ms |
 | Host start, 8 actors compiled in parallel | ~0.8 s each |
 | Host RSS with 8 running actors | ~117 MB |
 | First release build of `sausage` | ~9 min (Wasmtime) |
 Caveat: `~/.cargo/config.toml` in this container sets `kache` as the
 `rustc-wrapper`. `kache` caches compiler outputs across projects, so the
 first build of the agent (17 s) is probably faster than on a clean machine.
 ## Next steps I suggest
 1. A `matrix` actor (WASM, `wstd`, long-polled `/sync`). The agent could write
   it, with you checking the result.
 2. Cache compiled components (`Component::serialize`, `.cwasm` files) to
   remove the compile time at host start.
 3. A network allow-list per actor, for example in a manifest in the source
   folder.
 4. A sandbox for builds (for example `bwrap`), because build scripts run
   natively.
 5. Context compaction for the agent's conversation.
 6. A better console (line editing, history).
@@ -5,7 +5,7 @@ edition = "2024"
 description = "The Sausage agent actor."
 [dependencies]
-async-channel = "2"
+sausage-actor = { version = "0.1", path = "../sdk", features = ["async"] }
 serde = { version = "1", features = ["derive"] }
 serde_json = "1"
 wstd = "0.6"
@@ -0,0 +1,81 @@
 //! History window selection and context-size error detection.
 use crate::llm::Entry;
 pub fn is_too_large(error: &str) -> bool {
    let Some((status, body)) = error
        .strip_prefix("HTTP ")
        .and_then(|error| error.split_once(':'))
    else {
        return false;
    };
    if !matches!(status.split_whitespace().next(), Some("400" | "413")) {
        return false;
    }
    let body = body.to_ascii_lowercase();
    body.contains("context_length_exceeded")
        || body.contains("maximum context length")
        || body.contains("context length exceeded")
        || body.contains("too large")
        || (body.contains("too long")
            && ["context", "input", "prompt"]
                .iter()
                .any(|term| body.contains(term)))
 }
 pub fn next_turn_start(history: &[Entry], from: usize, current: usize) -> Option<usize> {
    let end = current.min(history.len().checked_sub(1)?);
    (from..=end).find(|&index| matches!(&history[index], Entry::User { .. }))
 }
 #[cfg(test)]
 mod tests {
    use super::*;
    #[test]
    fn detects_context_size_errors_only_for_http_400_or_413() {
        assert!(is_too_large("HTTP 400: context_length_exceeded"));
        assert!(is_too_large("HTTP 413: prompt is too long"));
        assert!(is_too_large("HTTP 400: maximum context length"));
        assert!(is_too_large("HTTP 400: request is too large"));
        assert!(!is_too_large("HTTP 500: prompt is too long"));
        assert!(!is_too_large("HTTP 400: invalid token"));
    }
    #[test]
    fn history_skip_advances_by_whole_user_turns() {
        let history = vec![
            Entry::User {
                text: "first".into(),
            },
            Entry::ToolCall {
                id: "a".into(),
                name: "tool".into(),
                arguments: "{}".into(),
            },
            Entry::ToolResult {
                id: "a".into(),
                output: "done".into(),
            },
            Entry::User {
                text: "second".into(),
            },
            Entry::ToolCall {
                id: "b".into(),
                name: "tool".into(),
                arguments: "{}".into(),
            },
            Entry::ToolResult {
                id: "b".into(),
                output: "done".into(),
            },
            Entry::User {
                text: "current".into(),
            },
        ];
        assert_eq!(next_turn_start(&history, 0, 6), Some(0));
        assert_eq!(next_turn_start(&history, 1, 6), Some(3));
        assert_eq!(next_turn_start(&history, 4, 6), Some(6));
        assert_eq!(next_turn_start(&history, usize::MAX, 6).unwrap_or(6), 6);
    }
 }
@@ -6,7 +6,6 @@
 use serde::{Deserialize, Serialize};
 use serde_json::{Value, json};
 use wstd::http::{Body, Client, Request};
 use wstd::time::Duration;
 #[derive(Deserialize, Clone)]
 pub struct Config {
@@ -18,19 +17,19 @@ pub struct Config {
    /// Optional reasoning effort for OpenAI models ("low", "medium", ...).
    #[serde(default)]
    pub reasoning_effort: Option<String>,
-    #[serde(default = "default_max_tokens")]
+    #[serde(default)]
-    pub max_tokens: u32,
+    pub max_tokens: Option<u32>,
 }
 fn default_max_tokens() -> u32 {
    16000
 }
 #[derive(Serialize, Deserialize, Clone, Debug)]
 #[serde(tag = "kind", rename_all = "snake_case")]
 pub enum Entry {
    User { text: String },
-    Assistant { text: String },
+    Assistant {
        text: String,
        #[serde(default, skip_serializing_if = "Option::is_none")]
        phase: Option<String>,
    },
    ToolCall { id: String, name: String, arguments: String },
    ToolResult { id: String, output: String },
    /// A provider item that only this API shape understands (OpenAI reasoning).
@@ -57,17 +56,13 @@ async fn post(url: &str, headers: &[(&str, String)], body: &Value) -> Result<Val
        req = req.header(*k, v.as_str());
    }
    let req = req.body(Body::from(body.to_string())).map_err(|e| format!("request: {e}"))?;
-    let mut client = Client::new();
+    let client = Client::new();
    client.set_first_byte_timeout(Duration::from_secs(600));
    client.set_between_bytes_timeout(Duration::from_secs(600));
    let resp = client.send(req).await.map_err(|e| format!("HTTP request failed: {e:?}"))?;
    let status = resp.status();
    let mut body = resp.into_body();
    let text = body.str_contents().await.map_err(|e| format!("reading the response failed: {e:?}"))?.to_string();
    if !status.is_success() {
-        let mut t = text;
+        return Err(format!("HTTP {status}: {text}"));
        t.truncate(2000);
        return Err(format!("HTTP {status}: {t}"));
    }
    serde_json::from_str(&text).map_err(|e| format!("invalid JSON in response: {e}"))
 }
@@ -77,7 +72,13 @@ async fn openai(cfg: &Config, system: &str, tools: &[Tool], history: &[Entry]) -
    for e in history {
        match e {
            Entry::User { text } => input.push(json!({"role": "user", "content": text})),
-            Entry::Assistant { text } => input.push(json!({"role": "assistant", "content": text})),
+            Entry::Assistant { text, phase } => {
                let mut item = json!({"role": "assistant", "content": text});
                if let Some(phase) = phase {
                    item["phase"] = json!(phase);
                }
                input.push(item);
            }
            Entry::ToolCall { id, name, arguments } => {
                input.push(json!({"type": "function_call", "call_id": id, "name": name, "arguments": arguments}))
            }
@@ -99,8 +100,10 @@ async fn openai(cfg: &Config, system: &str, tools: &[Tool], history: &[Entry]) -
        "tools": tools,
        "store": false,
        "include": ["reasoning.encrypted_content"],
        "max_output_tokens": cfg.max_tokens,
    });
    if let Some(max_tokens) = cfg.max_tokens {
        body["max_output_tokens"] = json!(max_tokens);
    }
    if let Some(effort) = &cfg.reasoning_effort {
        body["reasoning"] = json!({"effort": effort});
    }
@@ -120,8 +123,9 @@ async fn openai(cfg: &Config, system: &str, tools: &[Tool], history: &[Entry]) -
                            .collect()
                    })
                    .unwrap_or_default();
-                if !text.is_empty() {
+                let phase = item["phase"].as_str().map(str::to_string);
-                    out.push(Entry::Assistant { text });
+                if !text.is_empty() || phase.is_some() {
                    out.push(Entry::Assistant { text, phase });
                }
            }
            Some("function_call") => out.push(Entry::ToolCall {
@@ -149,7 +153,9 @@ async fn anthropic(cfg: &Config, system: &str, tools: &[Tool], history: &[Entry]
    for e in history {
        match e {
            Entry::User { text } => push("user", json!({"type": "text", "text": text})),
-            Entry::Assistant { text } => push("assistant", json!({"type": "text", "text": text})),
+            Entry::Assistant { text, .. } => {
                push("assistant", json!({"type": "text", "text": text}))
            }
            Entry::ToolCall { id, name, arguments } => {
                let input: Value = serde_json::from_str(arguments).unwrap_or(json!({}));
                push("assistant", json!({"type": "tool_use", "id": id, "name": name, "input": input}))
@@ -170,7 +176,7 @@ async fn anthropic(cfg: &Config, system: &str, tools: &[Tool], history: &[Entry]
        "system": system,
        "messages": messages,
        "tools": tools,
-        "max_tokens": cfg.max_tokens,
+        "max_tokens": cfg.max_tokens.unwrap_or(32000),
    });
    let url = format!("{}/v1/messages", cfg.base_url);
    let resp = post(
@@ -185,7 +191,7 @@ async fn anthropic(cfg: &Config, system: &str, tools: &[Tool], history: &[Entry]
            Some("text") => {
                let text = block["text"].as_str().unwrap_or_default().to_string();
                if !text.is_empty() {
-                    out.push(Entry::Assistant { text });
+                    out.push(Entry::Assistant { text, phase: None });
                }
            }
            Some("tool_use") => out.push(Entry::ToolCall {
@@ -1,242 +1,92 @@
-//! The Sausage agent: a normal WASM actor that does inference over HTTP and
+//! The Sausage agent actor.
 //! grows the world through messages to `cargo` and `broker`.
 //!
 //! Configuration: `/data/config.json` (see `llm::Config`).
 //! Conversation: `/data/history.json` (one shared conversation).
 mod history;
 mod llm;
 mod tools;
-use std::collections::VecDeque;
+use history::{is_too_large, next_turn_start};
-
+use llm::{Config, Entry};
-use async_channel::{Receiver, Sender};
+use sausage_actor::{Inbox, Message, Value, json, publish, send};
-use llm::{Config, Entry, Tool};
+use std::collections::{HashSet, VecDeque};
-use serde_json::{Value, json};
+use std::io::Write;
 use wstd::future::FutureExt;
 use wstd::io::{AsyncRead, AsyncWrite};
 use wstd::time::{Duration, Instant};
 const SYSTEM: &str = include_str!("prompt.md");
 const CONFIG: &str = "/data/config.json";
-const HISTORY: &str = "/data/history.json";
+const HISTORY: &str = "/data/history.jsonl";
-/// An interrupted turn (sender and message ID), resumed at the next start.
+const HISTORY_SKIP: &str = "/data/history.skip";
 const TURN: &str = "/data/turn.json";
 const MAX_STEPS: usize = 40;
 const MAX_HISTORY: usize = 600;
 const MAX_TOOL_OUTPUT: usize = 30_000;
 const MAX_NOTES: usize = 50;
 fn main() {
-    wstd::runtime::block_on(async {
+    wstd::runtime::block_on(async { Agent::new().run().await });
        let (tx, rx) = async_channel::unbounded();
        wstd::runtime::spawn(read_stdin(tx)).detach();
        Agent::new(rx).run().await;
    });
 }
 /// Read NDJSON messages from stdin into the channel.
 async fn read_stdin(tx: Sender<Value>) {
    let mut stdin = wstd::io::stdin();
    let mut buf = Vec::new();
    let mut chunk = vec![0u8; 16 * 1024];
    loop {
        match stdin.read(&mut chunk).await {
            Ok(0) | Err(_) => break,
            Ok(n) => {
                buf.extend_from_slice(&chunk[..n]);
                while let Some(pos) = buf.iter().position(|b| *b == b'\n') {
                    let line: Vec<u8> = buf.drain(..=pos).collect();
                    if let Ok(v) = serde_json::from_slice::<Value>(&line)
                        && tx.send(v).await.is_err()
                    {
                        return;
                    }
                }
            }
        }
    }
    tx.close();
 }
 fn truncate(mut s: String, max: usize) -> String {
    if s.len() > max {
        let mut end = max;
        while !s.is_char_boundary(end) {
            end -= 1;
        }
        let total = s.len();
        s.truncate(end);
        s.push_str(&format!("\n… (truncated, {total} bytes in total)"));
    }
    s
 }
 fn tools() -> Vec<Tool> {
    vec![
        Tool {
            name: "send_message",
            description: "Send a message to an actor. With wait_seconds > 0, wait for the reply (a message whose reply_to is the ID of this message). Returns the message ID, the reply (or null), and other messages that arrived meanwhile.",
            parameters: json!({
                "type": "object",
                "properties": {
                    "to": {"type": "string", "description": "Actor ID"},
                    "body": {"type": "object", "description": "Message body. Must have a \"type\" field."},
                    "wait_seconds": {"type": "number", "description": "Seconds to wait for the reply. 0 = do not wait."}
                },
                "required": ["to", "body"]
            }),
        },
        Tool {
            name: "wait_for_messages",
            description: "Wait up to `seconds` for messages to arrive and return them.",
            parameters: json!({
                "type": "object",
                "properties": {"seconds": {"type": "number"}},
                "required": ["seconds"]
            }),
        },
        Tool {
            name: "read_file",
            description: "Read a text file. Paths: /data/..., /public/..., /actor/<id>/...",
            parameters: json!({
                "type": "object",
                "properties": {
                    "path": {"type": "string"},
                    "offset": {"type": "integer", "description": "Byte offset (default 0)"},
                    "max_bytes": {"type": "integer", "description": "Default 30000"}
                },
                "required": ["path"]
            }),
        },
        Tool {
            name: "list_dir",
            description: "List a folder.",
            parameters: json!({
                "type": "object",
                "properties": {"path": {"type": "string"}},
                "required": ["path"]
            }),
        },
        Tool {
            name: "write_file",
            description: "Write a text file (only under /data or /public). Creates parent folders.",
            parameters: json!({
                "type": "object",
                "properties": {"path": {"type": "string"}, "content": {"type": "string"}},
                "required": ["path", "content"]
            }),
        },
        Tool {
            name: "copy_dir",
            description: "Copy a folder tree, for example /actor/<id>/source to /public/drafts/<id>. Skips target/ folders.",
            parameters: json!({
                "type": "object",
                "properties": {"from": {"type": "string"}, "to": {"type": "string"}},
                "required": ["from", "to"]
            }),
        },
        Tool {
            name: "remove_path",
            description: "Remove a file or folder under /data or /public.",
            parameters: json!({
                "type": "object",
                "properties": {"path": {"type": "string"}},
                "required": ["path"]
            }),
        },
    ]
 }
 fn copy_tree(from: &str, to: &str) -> std::io::Result<u64> {
    std::fs::create_dir_all(to)?;
    let mut n = 0;
    for entry in std::fs::read_dir(from)? {
        let entry = entry?;
        let name = entry.file_name().to_string_lossy().to_string();
        let src = format!("{from}/{name}");
        let dst = format!("{to}/{name}");
        if entry.file_type()?.is_dir() {
            if name != "target" {
                n += copy_tree(&src, &dst)?;
            }
        } else {
            std::fs::copy(&src, &dst)?;
            n += 1;
        }
    }
    Ok(n)
 }
 struct Agent {
-    rx: Receiver<Value>,
+    inbox: Inbox,
    stdout: wstd::io::Stdout,
    history: Vec<Entry>,
-    /// Text messages that start a new turn later.
+    history_skip: usize,
-    queue: VecDeque<Value>,
+    active: bool,
-    /// Other messages that arrived while the agent was idle.
+    queue: VecDeque<Message>,
-    notes: Vec<Value>,
+    notes: Vec<Message>,
    seq: u64,
    shutdown: bool,
 }
 impl Agent {
-    fn new(rx: Receiver<Value>) -> Self {
+    fn new() -> Self {
        let history = std::fs::read_to_string(HISTORY)
            .unwrap_or_default()
            .lines()
            .filter_map(|line| serde_json::from_str(line).ok())
            .collect();
        let history_skip = std::fs::read_to_string(HISTORY_SKIP)
            .ok()
-            .and_then(|s| serde_json::from_str(&s).ok())
+            .and_then(|skip| skip.trim().parse::<usize>().ok())
-            .unwrap_or_default();
+            .unwrap_or(0);
        let active = std::fs::read_to_string(TURN)
            .ok()
            .and_then(|contents| serde_json::from_str::<bool>(&contents).ok())
            .unwrap_or(false);
        Self {
-            rx,
+            inbox: Inbox::start(),
            stdout: wstd::io::stdout(),
            history,
            history_skip,
            active,
            queue: VecDeque::new(),
            notes: Vec::new(),
            seq: 0,
            shutdown: false,
        }
    }
-    async fn run(mut self) {
+    fn add_history(&mut self, entry: Entry) {
-        eprintln!("agent: started with {} history entries", self.history.len());
+        let line = serde_json::to_string(&entry).unwrap();
-        self.resume().await;
+        match std::fs::OpenOptions::new()
-        while !self.shutdown {
+            .create(true)
-            let msg = match self.queue.pop_front() {
+            .append(true)
-                Some(m) => m,
+            .open(HISTORY)
-                None => match self.rx.recv().await {
+        {
-                    Ok(m) => m,
+            Ok(mut file) => {
-                    Err(_) => break,
+                if let Err(e) = writeln!(file, "{line}") {
-                },
+                    eprintln!("agent: cannot append history: {e}");
            };
            if msg["body"]["type"] == "shutdown" {
                break;
            }
            if starts_turn(&msg) {
                self.turn(msg).await;
            } else {
                self.notes.push(msg);
                if self.notes.len() > MAX_NOTES {
                    self.notes.remove(0);
                }
            }
            Err(e) => eprintln!("agent: cannot append history: {e}"),
        }
-        self.save();
+        self.history.push(entry);
        eprintln!("agent: stopped");
    }
-    /// Continue a turn that a restart (usually an upgrade of the agent itself)
+    fn finish_turn(&mut self) {
-    /// interrupted.
+        self.active = false;
    async fn resume(&mut self) {
        let Some(turn) = std::fs::read_to_string(TURN).ok().and_then(|s| serde_json::from_str::<Value>(&s).ok()) else {
            return;
        };
        let _ = std::fs::remove_file(TURN);
-        let Ok(cfg) = std::fs::read_to_string(CONFIG).map_err(|_| ()).and_then(|s| serde_json::from_str::<Config>(&s).map_err(|_| ())) else {
+    }
-            return;
+
-        };
+    fn closing(&self) -> bool {
-        // Every tool call needs a result, or the APIs reject the history.
+        self.inbox.is_closed()
-        let answered: std::collections::HashSet<String> = self
+    }
    fn repair_dangling_tools(&mut self) {
        let answered: HashSet<String> = self
            .history
            .iter()
-            .filter_map(|e| match e {
+            .filter_map(|entry| match entry {
                Entry::ToolResult { id, .. } => Some(id.clone()),
                _ => None,
            })
@@ -244,277 +94,246 @@ impl Agent {
        let dangling: Vec<String> = self
            .history
            .iter()
-            .filter_map(|e| match e {
+            .filter_map(|entry| match entry {
                Entry::ToolCall { id, .. } if !answered.contains(id) => Some(id.clone()),
                _ => None,
            })
            .collect();
        for id in dangling {
-            self.history.push(Entry::ToolResult {
+            self.add_history(Entry::ToolResult {
                id,
-                output: json!({"error": "interrupted: the agent restarted before this tool finished"}).to_string(),
+                output:
                    json!({"error": "interrupted: the agent restarted before this tool finished"})
                        .to_string(),
            });
        }
        let version = std::env::var("SAUSAGE_VERSION").unwrap_or_default();
        self.history.push(Entry::User {
            text: format!(
                "[note from your runtime] You restarted and now run version {version}. The restart interrupted your last turn (probably your own upgrade). Check the state you need, then finish the turn and answer the original message."
            ),
        });
        eprintln!("agent: resuming an interrupted turn");
        self.steps(&cfg, turn["from"].clone(), turn["id"].clone()).await;
    }
-    fn save(&mut self) {
+    fn turn_text(&self, message: &Message) -> String {
        if self.history.len() > MAX_HISTORY {
            let start = self.history.len() - MAX_HISTORY;
            let cut = (start..self.history.len())
                .find(|i| matches!(self.history[*i], Entry::User { .. }))
                .unwrap_or(start);
            self.history.drain(..cut);
        }
        if let Ok(s) = serde_json::to_string(&self.history)
            && let Err(e) = std::fs::write(HISTORY, s)
        {
            eprintln!("agent: cannot save history: {e}");
        }
    }
    async fn emit(&mut self, msg: Value) {
        let mut line = msg.to_string();
        line.push('\n');
        if self.stdout.write_all(line.as_bytes()).await.is_err() || self.stdout.flush().await.is_err() {
            eprintln!("agent: cannot write to stdout");
        }
    }
    async fn reply(&mut self, to: &Value, reply_to: &Value, text: String) {
        self.emit(json!({"to": to, "reply_to": reply_to, "body": {"type": "text", "text": text}})).await;
    }
    /// Sort a message that arrived during a turn.
    fn stash(&mut self, m: Value, others: &mut Vec<Value>) {
        if m["body"]["type"] == "shutdown" {
            self.shutdown = true;
        } else if starts_turn(&m) {
            others.push(json!({"queued_for_a_later_turn": true, "message": m}));
            self.queue.push_back(m);
        } else {
            others.push(m);
        }
    }
    async fn turn(&mut self, msg: Value) {
        let from = msg["from"].clone();
        let id = msg["id"].clone();
        let cfg: Config = match std::fs::read_to_string(CONFIG).map_err(|e| e.to_string()).and_then(|s| serde_json::from_str(&s).map_err(|e| e.to_string())) {
            Ok(c) => c,
            Err(e) => {
                self.reply(&from, &id, format!("I am not configured: cannot read {CONFIG}: {e}")).await;
                return;
            }
        };
        let mut text = format!(
            "Message {} from {}:\n{}",
-            id.as_str().unwrap_or("?"),
+            message.id,
-            from.as_str().unwrap_or("?"),
+            message.from,
-            msg["body"]["text"].as_str().unwrap_or("")
+            message.body["text"].as_str().unwrap_or("")
        );
        if !self.notes.is_empty() {
-            let notes: Vec<String> = self.notes.drain(..).map(|n| n.to_string()).collect();
+            let notes = self
-            text = format!("Messages that arrived while you were idle:\n{}\n\n{text}", notes.join("\n"));
+                .notes
                .iter()
                .map(|note| serde_json::to_string(note).unwrap())
                .collect::<Vec<_>>()
                .join("\n");
            text = format!("Messages that arrived while you were idle:\n{notes}\n\n{text}");
        }
-        self.history.push(Entry::User { text });
+        text
        self.steps(&cfg, from, id).await;
    }
-    /// Run inference and tools until the model answers. If a shutdown
+    fn not_configured(&mut self, error: String) {
-    /// interrupts the turn, remember it in TURN so the next start resumes it.
+        let _ = publish(json!({
-    async fn steps(&mut self, cfg: &Config, from: Value, id: Value) {
+            "type": "text",
-        let tools = tools();
+            "text": format!("I am not configured: cannot read {CONFIG}: {error}")
-        let cfg = cfg.clone();
+        }));
-        for _ in 0..MAX_STEPS {
+        self.finish_turn();
-            let started = Instant::now();
+    }
-            let result = llm::complete(&cfg, SYSTEM, &tools, &self.history).await;
+
-            let entries = match result {
+    async fn run(mut self) {
-                Ok(e) => e,
+        self.repair_dangling_tools();
        if self.active {
            self.turn(None).await;
            if self.closing() && self.active {
                return;
            }
        }
        loop {
            let message = match self.queue.pop_front() {
                Some(message) => message,
                None => match self.inbox.recv().await {
                    Some(message) => message,
                    None => break,
                },
            };
            if starts_turn(&message) {
                self.turn(Some(message)).await;
                if self.closing() && self.active {
                    break;
                }
            } else {
                self.notes.push(message);
            }
        }
    }
    async fn turn(&mut self, message: Option<Message>) {
        let current_start = if message.is_some() {
            self.active = true;
            let _ = std::fs::write(TURN, "true");
            self.history.len()
        } else {
            let current_start = self
                .history
                .iter()
                .rposition(|entry| matches!(entry, Entry::User { text } if !text.starts_with("[note from your runtime]")))
                .unwrap_or(self.history.len());
            let version = std::env::var("SAUSAGE_VERSION").unwrap_or_default();
            self.add_history(Entry::User {
                text: format!(
                    "[note from your runtime] you restarted and now run version {version}. Continue the active turn."
                ),
            });
            current_start
        };
        let cfg = match load_config() {
            Ok(cfg) => cfg,
            Err(error) => {
                self.not_configured(error);
                return;
            }
        };
        if let Some(message) = message {
            let text = self.turn_text(&message);
            self.notes.clear();
            self.add_history(Entry::User { text });
        }
        self.steps(&cfg, current_start).await;
        if !self.closing() {
            self.finish_turn();
        }
    }
    async fn steps(&mut self, cfg: &Config, current_start: usize) {
        let tools = tools::definitions();
        loop {
            if self.closing() {
                return;
            }
            let start = next_turn_start(&self.history, self.history_skip, current_start)
                .unwrap_or(current_start);
            if start != self.history_skip {
                self.history_skip = start;
                let _ = std::fs::write(HISTORY_SKIP, start.to_string());
            }
            let response = llm::complete(cfg, SYSTEM, &tools, &self.history[start..]).await;
            let entries = match response {
                Ok(entries) => entries,
                Err(e) => {
-                    eprintln!("agent: inference failed: {e}");
+                    if is_too_large(&e) {
-                    self.history.push(Entry::Assistant { text: format!("(inference failed: {e})") });
+                        if let Some(next) =
-                    self.save();
+                            next_turn_start(&self.history, start.saturating_add(1), current_start)
-                    self.reply(&from, &id, format!("Inference failed: {e}")).await;
+                        {
                            self.history_skip = next;
                            let _ = std::fs::write(HISTORY_SKIP, next.to_string());
                            continue;
                        }
                    }
                    let text = format!("Inference failed: {e}");
                    self.add_history(Entry::Assistant {
                        text: text.clone(),
                        phase: None,
                    });
                    let _ = publish(json!({"type": "text", "text": text}));
                    return;
                }
            };
            eprintln!("agent: inference took {:?}", started.elapsed());
            let calls: Vec<(String, String, String)> = entries
                .iter()
-                .filter_map(|e| match e {
+                .filter_map(|entry| match entry {
-                    Entry::ToolCall { id, name, arguments } => Some((id.clone(), name.clone(), arguments.clone())),
+                    Entry::ToolCall {
                        id,
                        name,
                        arguments,
                    } => Some((id.clone(), name.clone(), arguments.clone())),
                    _ => None,
                })
                .collect();
-            let answer: Vec<String> = entries
+            for entry in entries {
-                .iter()
+                if let Entry::Assistant { text, .. } = &entry {
-                .filter_map(|e| match e {
+                    if !text.is_empty() {
-                    Entry::Assistant { text } => Some(text.clone()),
+                        let _ = publish(json!({"type": "text", "text": text}));
-                    _ => None,
+                    }
-                })
+                }
-                .collect();
+                self.add_history(entry);
-            self.history.extend(entries);
+            }
            if self.closing() {
                return;
            }
            if calls.is_empty() {
                self.save();
                let answer = if answer.is_empty() { "(no answer)".to_string() } else { answer.join("\n\n") };
                self.reply(&from, &id, answer).await;
                return;
            }
-            for (call_id, name, args) in calls {
+            for (id, name, args) in calls {
                if self.closing() {
                    return;
                }
                let output = self.tool(&name, &args).await;
-                self.history.push(Entry::ToolResult { id: call_id, output: truncate(output.to_string(), MAX_TOOL_OUTPUT) });
+                self.add_history(Entry::ToolResult {
-            }
+                    id,
-            self.save();
+                    output: output.to_string(),
-            if self.shutdown {
+                });
                let _ = std::fs::write(TURN, json!({"from": from, "id": id}).to_string());
                eprintln!("agent: turn interrupted by shutdown; it resumes after the restart");
                return;
            }
        }
-        self.reply(&from, &id, format!("I stopped after {MAX_STEPS} steps. Tell me to continue if you want.")).await;
+    }
    fn stash(&mut self, message: Message, others: &mut Vec<Value>) {
        if starts_turn(&message) {
            others.push(json!({"queued_for_a_later_turn": true, "message": message}));
            self.queue.push_back(message);
        } else {
            others.push(serde_json::to_value(message).unwrap());
        }
    }
    fn drain_inbox(&mut self, others: &mut Vec<Value>) {
        while let Some(message) = self.inbox.try_recv() {
            self.stash(message, others);
        }
    }
    async fn tool(&mut self, name: &str, args: &str) -> Value {
-        let a: Value = match serde_json::from_str(args) {
+        let args: Value = match serde_json::from_str(args) {
-            Ok(v) => v,
+            Ok(args) => args,
-            Err(e) => return json!({"error": format!("arguments are not valid JSON: {e}")}),
+            Err(error) => return json!({"error": format!("arguments are not valid JSON: {error}")}),
        };
-        let path = |k: &str| a[k].as_str().unwrap_or_default().to_string();
+        if name == "send_message" {
-        let err = |e: std::io::Error| json!({"error": e.to_string()});
+            return self.send_message(&args).await;
        match name {
            "send_message" => self.send_message(&a).await,
            "wait_for_messages" => {
                let secs = a["seconds"].as_f64().unwrap_or(10.0).clamp(0.0, 900.0);
                let mut others = Vec::new();
                match self.rx.recv().timeout(Duration::from_secs_f64(secs)).await {
                    Ok(Ok(m)) => {
                        self.stash(m, &mut others);
                        while let Ok(m) = self.rx.try_recv() {
                            self.stash(m, &mut others);
                        }
                    }
                    Ok(Err(_)) => self.shutdown = true,
                    Err(_) => {}
                }
                json!({"messages": others})
            }
            "read_file" => {
                let p = path("path");
                match std::fs::read(&p) {
                    Ok(bytes) => {
                        let offset = (a["offset"].as_u64().unwrap_or(0) as usize).min(bytes.len());
                        let max = a["max_bytes"].as_u64().unwrap_or(30_000) as usize;
                        let end = (offset + max).min(bytes.len());
                        json!({
                            "path": p, "size": bytes.len(), "offset": offset,
                            "content": String::from_utf8_lossy(&bytes[offset..end]),
                            "truncated": end < bytes.len(),
                        })
                    }
                    Err(e) => err(e),
                }
            }
            "list_dir" => match std::fs::read_dir(path("path")) {
                Ok(rd) => {
                    let mut entries: Vec<Value> = rd
                        .filter_map(|e| e.ok())
                        .take(500)
                        .map(|e| {
                            let meta = e.metadata().ok();
                            json!({
                                "name": e.file_name().to_string_lossy(),
                                "type": if meta.as_ref().is_some_and(|m| m.is_dir()) { "dir" } else { "file" },
                                "size": meta.map(|m| m.len()),
                            })
                        })
                        .collect();
                    entries.sort_by(|x, y| x["name"].as_str().cmp(&y["name"].as_str()));
                    json!({"entries": entries})
                }
                Err(e) => err(e),
            },
            "write_file" => {
                let p = path("path");
                if let Some(parent) = std::path::Path::new(&p).parent() {
                    let _ = std::fs::create_dir_all(parent);
                }
                match std::fs::write(&p, a["content"].as_str().unwrap_or_default()) {
                    Ok(()) => json!({"written": p}),
                    Err(e) => err(e),
                }
            }
            "copy_dir" => match copy_tree(&path("from"), &path("to")) {
                Ok(n) => json!({"copied_files": n}),
                Err(e) => err(e),
            },
            "remove_path" => {
                let p = path("path");
                let r = if std::path::Path::new(&p).is_dir() { std::fs::remove_dir_all(&p) } else { std::fs::remove_file(&p) };
                match r {
                    Ok(()) => json!({"removed": p}),
                    Err(e) => err(e),
                }
            }
            other => json!({"error": format!("unknown tool {other}")}),
        }
        tools::run(name, &args).unwrap_or_else(|error| json!({"error": error.to_string()}))
    }
-    async fn send_message(&mut self, a: &Value) -> Value {
+    async fn send_message(&mut self, args: &Value) -> Value {
-        let Some(to) = a["to"].as_str() else { return json!({"error": "missing \"to\""}) };
+        let Some(to) = args["to"].as_str() else {
-        if !a["body"].is_object() {
+            return json!({"error": "missing \"to\""});
        };
        if !args["body"].is_object() {
            return json!({"error": "\"body\" must be a JSON object"});
        }
-        self.seq += 1;
+        let id = send(to, args["body"].clone());
-        let own = format!("a{}-{}", wstd_now_ms(), self.seq);
+        let wait = args["wait_seconds"].as_f64().unwrap_or(0.0).max(0.0);
        let full = format!("agent/{own}");
        self.emit(json!({"to": to, "id": own, "body": a["body"]})).await;
        let wait = a["wait_seconds"].as_f64().unwrap_or(0.0).clamp(0.0, 900.0);
        let mut reply = Value::Null;
        let mut others = Vec::new();
        if wait > 0.0 {
            let deadline = Instant::now() + Duration::from_secs_f64(wait);
            loop {
-                match self.rx.recv().timeout(deadline).await {
+                match self.inbox.recv().timeout(deadline).await {
-                    Ok(Ok(m)) => {
+                    Ok(Some(message)) if message.reply_to.as_deref() == Some(&id) => {
-                        if m["reply_to"] == full.as_str() {
+                        reply = serde_json::to_value(message).unwrap();
                            reply = m;
                            break;
                        }
                        self.stash(m, &mut others);
                        if self.shutdown {
                            break;
                        }
                    }
                    Ok(Err(_)) => {
                        // stdin closed: the broker stops us.
                        self.shutdown = true;
                        break;
                    }
                    Ok(Some(message)) => self.stash(message, &mut others),
                    Ok(None) => break,
                    Err(_) => break,
                }
            }
        }
-        json!({"id": full, "reply": reply, "waited": wait > 0.0, "other_messages": others})
+        self.drain_inbox(&mut others);
        json!({"id": id, "reply": reply, "waited": wait > 0.0, "other_messages": others})
    }
 }
-/// A text message that is not a reply starts a turn. Replies never do, so
+fn load_config() -> Result<Config, String> {
-/// two actors cannot keep the agent in an endless conversation.
+    std::fs::read_to_string(CONFIG)
-fn starts_turn(m: &Value) -> bool {
+        .map_err(|e| e.to_string())
-    m["body"]["type"] == "text" && m.get("reply_to").is_none_or(Value::is_null)
+        .and_then(|contents| serde_json::from_str(&contents).map_err(|e| e.to_string()))
 }
-fn wstd_now_ms() -> u64 {
+fn starts_turn(message: &Message) -> bool {
-    std::time::SystemTime::now()
+    message.kind() == "text" && message.reply_to.is_none()
        .duration_since(std::time::UNIX_EPOCH)
        .map(|d| d.as_millis() as u64)
        .unwrap_or(0)
 }
@@ -1,80 +1,5 @@
-You are the agent of a Sausage world. Your actor ID is `agent`.
+You are the `agent` actor in a Sausage world of actors.
-
+People talk to you through other actors. Your text goes to your subscribers.
-Sausage is a system of actors. Each actor is a WASI program (a `.wasm` file). Actors talk only through messages. People talk to you through other actors, for example `console` (a terminal) or later `matrix`. You help them by using actors, and by writing, testing, and upgrading actors. You can also change your own code.
+Before writing an actor, read `/actor/broker/public/PROTOCOL.md` for messages, the broker, `cargo`, and tests.
-
+Read the SDK at `/actor/cargo/public/sdk/` before you write an actor.
-# Messages
+You can change your own source at `/actor/agent/source`.
 Every message has a sender (`from`), an ID, an optional `reply_to` (the ID of the message it answers), and a JSON `body`. A body is an object with a `"type"` field. There is no request/response: a reply is a new message with `reply_to` set. Delivery is at most once.
 A WASM actor reads one JSON object per line on stdin:
 `{"id":"m-17","from":"console","body":{...}}`
 and writes one JSON object per line on stdout:
 `{"to":"console","reply_to":"m-17","body":{...}}`
 Without `"to"`, the broker publishes the message to the subscribers of the sender. An actor may set its own `"id"`. The broker then uses `"<sender>/<id>"`. stdout is only for messages. Logs go to stderr. The broker sends `{"type":"shutdown"}` before it stops an actor. EOF on stdin means "stop now".
 # Filesystem
 Each actor sees:
 - `/data`: private state, read-write. Only the actor itself sees it.
 - `/public`: its public files, read-write.
 - `/actor/<id>/public`: the public files of every actor, read-only.
 - `/actor/<id>/source`: the source of the running version of every actor, read-only.
 - `/actor/<id>/status.json` and `/actor/<id>/stderr.log`: state and stderr log of every actor.
 `ls /actor` lists all actors. A write becomes visible to other actors only when the writer closes the file. Send large or binary data as a file path, not in a message.
 # Built-in actors
 `broker` (only accepts `.wasm` files, knows no source language):
 - `{"type":"spawn","actor":"<new-id>","wasm":"<path>","source":"<folder>","built_by":"cargo"}`
 - `{"type":"upgrade","actor":"<id>","wasm":"<path>","source":"<folder>","built_by":"cargo"}`
 - `{"type":"rollback","actor":"<id>"}` (optional `"version"`)
 - `{"type":"stop","actor":"<id>"}`, `{"type":"start","actor":"<id>"}`, `{"type":"remove","actor":"<id>"}` (archives, never deletes)
 - `{"type":"subscribe","actor":"<id>"}`, `{"type":"unsubscribe","actor":"<id>"}`, `{"type":"list"}`
 Before an upgrade or spawn, the broker tests the candidate on a copy of the actor's `/data` and `/public`, with no HTTP access. The tests are message transcripts in `<source>/tests/*.jsonl`. Each line is `{"send": <body>}` or `{"expect": <subset of the reply body>}` (optional `"to"`). Without test files, the candidate must start and stay up for 2 seconds. If a new version crashes 3 times within 30 seconds, the broker rolls it back automatically. The broker keeps the message that crashed an actor and delivers it again after the next upgrade.
 `cargo` (built-in Rust compiler):
 - `{"type":"build","source":"<folder with Cargo.toml>"}` → `{"type":"built","wasm":"/actor/cargo/public/builds/<n>/<name>.wasm",...}` or `{"type":"build_failed","errors":"..."}`. A build can take a minute. Wait up to 600 seconds for the reply.
 # Writing an actor in Rust
 1. Write the crate to `/public/drafts/<name>/`: `Cargo.toml`, `src/main.rs`, and `tests/*.jsonl`. Use `edition = "2024"`. Use `serde_json` for messages.
 2. Send `build` to `cargo` with the folder path `/actor/agent/public/drafts/<name>` and wait for the reply. Fix compiler errors and build again.
 3. Send `spawn` (new actor) or `upgrade` (existing actor) to `broker` with the `wasm` path from the build reply and the same `source` folder. Wait for the reply.
 4. Send a message to the new actor to check it.
 A simple actor that only reacts to messages can block on stdin:
 ```rust
 use serde_json::{json, Value};
 use std::io::{BufRead, Write};
 fn main() {
    let mut out = std::io::stdout().lock();
    for line in std::io::stdin().lock().lines() {
        let Ok(line) = line else { break };
        let Ok(msg) = serde_json::from_str::<Value>(&line) else { continue };
        let body = &msg["body"];
        let reply = match body["type"].as_str() {
            Some("shutdown") => break,
            Some("ping") => json!({"type": "pong"}),
            _ => json!({"type": "error", "reason": "unknown message"}),
        };
        writeln!(out, "{}", json!({"to": msg["from"], "reply_to": msg["id"], "body": reply})).unwrap();
        out.flush().unwrap();
    }
 }
 ```
 An actor that needs HTTP or timers and must also read messages uses the async `wstd` crate (`wstd = "0.6"`): `#[wstd::main] async fn main()`, `wstd::io::stdin()` (`AsyncRead`), `wstd::io::stdout()` (`AsyncWrite`, `write_all`, `flush`), `wstd::http::{Client, Request, Body}` (`Client::new().send(Request::get(url).body(Body::empty())?).await?`, then `response.into_body().contents().await?`), `wstd::task::sleep(wstd::time::Duration::from_secs(n)).await`, and `wstd::runtime::spawn(future)`. Actors have outgoing HTTP and HTTPS only, no raw sockets. Threads are not available. Store state in `/data` so it survives restarts and upgrades. A new version must read the data format of the old version.
 # Changing yourself
 Your own source is at `/actor/agent/source`. To change yourself, copy it to `/public/drafts/agent`, edit the copy, build it, and upgrade `agent`. The upgrade restarts you, and the conversation continues from `/data`. Be careful: if the new version cannot answer, the person must roll you back through the console. Change yourself only when the person asks for it.
 # How to work
 - Use tools to look at the real state before you claim anything. Read files instead of guessing.
 - Keep answers short and concrete. Say what you changed and whether it worked.
 - Your final text in a turn goes back to the person who wrote to you.
@@ -0,0 +1,138 @@
 //! Tool descriptions and file operations for the agent.
 use crate::llm::Tool;
 use sausage_actor::{Value, json};
 use std::io;
 pub fn definitions() -> Vec<Tool> {
    vec![
        Tool {
            name: "send_message",
            description: "Send an actor a JSON body with a `type`. `broker` and `cargo` are built-in actors; see `/actor/broker/public/PROTOCOL.md`. With `wait_seconds`, the reply's `reply_to` matches the returned ID. Returns the ID, reply, and other messages received.",
            parameters: schema(
                json!({
                    "to": {"type": "string", "description": "Actor ID"},
                    "body": {"type": "object", "description": "JSON object with a type field"},
                    "wait_seconds": {"type": "number", "description": "Seconds to wait for a reply. Default 0."}
                }),
                &["to", "body"],
            ),
        },
        Tool {
            name: "read_file",
            description: "Read a text file under `/data`, `/public`, or `/actor/<id>`. Reads all bytes by default; `offset` and `max_bytes` are optional.",
            parameters: schema(
                json!({
                    "path": {"type": "string"},
                    "offset": {"type": "integer", "description": "Byte offset (default 0)"},
                    "max_bytes": {"type": "integer", "description": "Optional maximum number of bytes to read"}
                }),
                &["path"],
            ),
        },
        Tool {
            name: "write_file",
            description: "Write text under `/data` or `/public`. Parent folders are created.",
            parameters: schema(
                json!({"path": {"type": "string"}, "content": {"type": "string"}}),
                &["path", "content"],
            ),
        },
        Tool {
            name: "list_dir",
            description: "List entries in a directory under `/data`, `/public`, or `/actor/<id>`. Returns each name, type, and size.",
            parameters: schema(json!({"path": {"type": "string"}}), &["path"]),
        },
        Tool {
            name: "copy_dir",
            description: "Copy a directory tree, for example `/actor/<id>/source` to `/public/drafts/<id>`. Skips `target/` folders.",
            parameters: schema(
                json!({"from": {"type": "string"}, "to": {"type": "string"}}),
                &["from", "to"],
            ),
        },
    ]
 }
 fn schema(properties: Value, required: &[&str]) -> Value {
    json!({"type": "object", "properties": properties, "required": required})
 }
 pub fn run(name: &str, args: &Value) -> io::Result<Value> {
    match name {
        "read_file" => read_file(args),
        "write_file" => write_file(args),
        "list_dir" => list_dir(args),
        "copy_dir" => copy_dir(args),
        other => Ok(json!({"error": format!("unknown tool {other}")})),
    }
 }
 fn read_file(args: &Value) -> io::Result<Value> {
    let path = args["path"].as_str().unwrap_or_default();
    let bytes = std::fs::read(path)?;
    let offset = (args["offset"].as_u64().unwrap_or(0) as usize).min(bytes.len());
    let end = args["max_bytes"].as_u64().map_or(bytes.len(), |max| {
        offset.saturating_add(max as usize).min(bytes.len())
    });
    Ok(json!({
        "path": path,
        "size": bytes.len(),
        "offset": offset,
        "content": String::from_utf8_lossy(&bytes[offset..end]),
        "truncated": end < bytes.len(),
    }))
 }
 fn write_file(args: &Value) -> io::Result<Value> {
    let path = args["path"].as_str().unwrap_or_default();
    if let Some(parent) = std::path::Path::new(path).parent() {
        let _ = std::fs::create_dir_all(parent);
    }
    std::fs::write(path, args["content"].as_str().unwrap_or_default())?;
    Ok(json!({"written": path}))
 }
 fn list_dir(args: &Value) -> io::Result<Value> {
    let mut entries: Vec<Value> = std::fs::read_dir(args["path"].as_str().unwrap_or_default())?
        .filter_map(|entry| entry.ok())
        .map(|entry| {
            let metadata = entry.metadata().ok();
            json!({
                "name": entry.file_name().to_string_lossy(),
                "type": if metadata.as_ref().is_some_and(|meta| meta.is_dir()) { "dir" } else { "file" },
                "size": metadata.map(|meta| meta.len()),
            })
        })
        .collect();
    entries.sort_by(|left, right| left["name"].as_str().cmp(&right["name"].as_str()));
    Ok(json!({"entries": entries}))
 }
 fn copy_dir(args: &Value) -> io::Result<Value> {
    let count = copy_tree(
        args["from"].as_str().unwrap_or_default(),
        args["to"].as_str().unwrap_or_default(),
    )?;
    Ok(json!({"copied_files": count}))
 }
 fn copy_tree(from: &str, to: &str) -> io::Result<u64> {
    std::fs::create_dir_all(to)?;
    let mut count = 0;
    for entry in std::fs::read_dir(from)? {
        let entry = entry?;
        let name = entry.file_name().to_string_lossy().to_string();
        let src = format!("{from}/{name}");
        let dst = format!("{to}/{name}");
        if entry.file_type()?.is_dir() {
            if name != "target" {
                count += copy_tree(&src, &dst)?;
            }
        } else {
            std::fs::copy(src, dst)?;
            count += 1;
        }
    }
    Ok(count)
 }
@@ -0,0 +1,6 @@
 {
  "description": "the agent answers text with text, even without config or network",
  "steps": [
    {"send": {"type": "text", "text": "Hello"}, "expect": {"type": "text"}}
  ]
 }
@@ -1,3 +0,0 @@
 // The agent answers a text message with text, even without config or network.
 {"send": {"type": "text", "text": "Hello"}}
 {"expect": {"type": "text"}}
@@ -18,6 +18,7 @@ include_dir = "0.7"
 serde = { version = "1", features = ["derive"] }
 serde_json = "1"
 tokio = { version = "1", features = ["full"] }
 toml_edit = "0.25"
 wasmtime = "49"
 wasmtime-wasi = "49"
 wasmtime-wasi-http = "49"
@@ -1,18 +1,25 @@
 //! Tests for a candidate version, before the broker installs it.
 //!
-//! A test is a message transcript in `source/tests/*.jsonl`. Each line is one
+//! A test is a JSON file in `source/tests/*.json`, one scenario per file:
 //! of:
 //!
-//! ```text
+//! ```json
-//! {"send": {...body...}}                 send a message to the candidate
+//! {
-//! {"send": {...}, "from": "someone"}      with an explicit sender
+//!   "description": "add, then list",
-//! {"expect": {...subset of body...}}      the next message from the candidate
+//!   "steps": [
-//! {"expect": {...}, "to": "someone"}      and its recipient
+//!     {"send": {"type": "add", "text": "milk"}, "expect": {"type": "added"}},
 //!     {"send": {"type": "list"}, "from": "someone", "expect": [{"type": "notes"}], "to": "someone"}
 //!   ]
 //! }
 //! ```
 //!
 //! Each step sends `send` (optional, from `from` or "test"), then reads one
 //! message for each entry of `expect` (an object or a list). An expected body
 //! matches if it is a subset of the actual body. With `to`, each message must
 //! also go to that recipient.
 //!
 //! Each file runs in a fresh instance on a copy of the actor's `/data` and
-//! `/public`. The candidate has no HTTP access. Without test files, the
+//! `/public` (empty folders for a new actor), without network. A version
-//! candidate must start and stay up for `SMOKE_TIME`.
+//! without test files passes.
 use std::path::Path;
 use std::time::Duration;
@@ -22,11 +29,9 @@ use serde_json::{Value, json};
 use wasmtime::component::Component;
 use crate::broker::{Broker, SHUTDOWN_DEADLINE, shutdown_line, truncate};
-use crate::fs::Mount;
+use crate::runtime::Instance;
 use crate::runtime::{Instance, InstanceConfig};
 use crate::world;
 const SMOKE_TIME: Duration = Duration::from_secs(2);
 const EXPECT_TIMEOUT: Duration = Duration::from_secs(10);
 /// `expected` matches `actual` if every key of an expected object exists in
@@ -59,130 +64,93 @@ fn stderr_tail(path: &Path) -> String {
    text[s..].to_string()
 }
-pub async fn test(
+/// The version under test, which starts from a copy of the actor's state.
-    broker: &Broker,
+struct Candidate<'a> {
-    id: &str,
+    broker: &'a Broker,
-    component: &Component,
+    id: &'a str,
-    source: &Path,
+    version: u64,
-    data: Option<&Path>,
+    component: &'a Component,
-    public: Option<&Path>,
+}
-) -> Result<Value> {
+
 /// Run every test file of `<source>/tests/`.
 pub async fn test(broker: &Broker, id: &str, version: u64, component: &Component, source: Option<&Path>) -> Result<Value> {
    let candidate = Candidate { broker, id, version, component };
    let Some(source) = source else { return Ok(json!({"passed": []})) };
    let mut files: Vec<_> = std::fs::read_dir(source.join("tests"))
-        .map(|rd| {
+        .map(|rd| rd.filter_map(|e| Some(e.ok()?.path())).filter(|p| p.extension().is_some_and(|x| x == "json")).collect())
            rd.filter_map(|e| e.ok())
                .map(|e| e.path())
                .filter(|p| p.extension().is_some_and(|x| x == "jsonl"))
                .collect()
        })
        .unwrap_or_default();
    files.sort();
    if files.is_empty() {
        let (mut inst, scratch) = start(broker, id, component, data, public)?;
        tokio::time::sleep(SMOKE_TIME).await;
        if inst.is_finished() {
            let exit = inst.wait().await;
            bail!(
                "candidate ended during the smoke test ({exit}). stderr:\n{}",
                stderr_tail(&scratch.dir.join("stderr.log"))
            );
        }
        inst.stop(&shutdown_line(), SHUTDOWN_DEADLINE).await;
        return Ok(json!({"smoke_test": "passed", "files": 0}));
    }
    let mut passed = Vec::new();
    for file in &files {
        let name = file.file_name().unwrap().to_string_lossy().to_string();
-        run_file(broker, id, component, data, public, file)
+        candidate.run_file(file).await.map_err(|e| anyhow!("test {name} failed: {e:#}"))?;
            .await
            .map_err(|e| anyhow!("test {name} failed: {e:#}"))?;
        passed.push(name);
    }
    Ok(json!({"passed": passed}))
 }
-fn start(broker: &Broker, id: &str, component: &Component, data: Option<&Path>, public: Option<&Path>) -> Result<(Instance, Scratch)> {
+impl Candidate<'_> {
-    let dir = broker.world.scratch_dir().join(format!("{id}-{}-{}", world::now(), rand_suffix()));
+    /// Start an instance on a fresh copy of the state, without network.
    fn start(&self) -> Result<(Instance, Scratch)> {
        static N: std::sync::atomic::AtomicU64 = std::sync::atomic::AtomicU64::new(0);
        let n = N.fetch_add(1, std::sync::atomic::Ordering::Relaxed);
        let dir = self.broker.world.scratch_dir().join(format!("{}-{}-{n}", self.id, std::process::id()));
        let scratch = Scratch { dir: dir.clone() };
-    std::fs::create_dir_all(dir.join("data"))?;
+        let world = &self.broker.world;
-    std::fs::create_dir_all(dir.join("public"))?;
+        for (from, name) in [(world.data_dir(self.id), "data"), (world.public_dir(self.id), "public")] {
-    if let Some(d) = data.filter(|d| d.is_dir()) {
+            std::fs::create_dir_all(dir.join(name))?;
-        world::copy_tree(d, &dir.join("data"))?;
+            if from.is_dir() {
                world::copy_tree(&from, &dir.join(name))?;
            }
    if let Some(p) = public.filter(|p| p.is_dir()) {
        world::copy_tree(p, &dir.join("public"))?;
        }
-    let cfg = InstanceConfig {
+        let cfg = self.broker.instance_config(self.id, self.version, Some(&dir));
-        mounts: vec![
+        Ok((self.broker.runtime.start(self.component, cfg)?, scratch))
-            Mount { guest: "/actor".into(), host: broker.world.actors_root(), writable: false },
+    }
            Mount { guest: "/public".into(), host: dir.join("public"), writable: true },
            Mount { guest: "/data".into(), host: dir.join("data"), writable: true },
        ],
        allow_http: false,
        stderr_log: dir.join("stderr.log"),
        env: vec![("SAUSAGE_ACTOR".into(), id.to_string()), ("SAUSAGE_CANDIDATE".into(), "1".into())],
    };
    Ok((broker.runtime.start(component, cfg)?, scratch))
 }
-fn rand_suffix() -> u32 {
+    async fn run_file(&self, file: &Path) -> Result<()> {
-    use std::hash::{BuildHasher, Hasher};
+        let test: Value = serde_json::from_str(&std::fs::read_to_string(file)?).map_err(|e| anyhow!("invalid JSON: {e}"))?;
-    let mut h = std::collections::hash_map::RandomState::new().build_hasher();
+        let steps = test["steps"].as_array().ok_or_else(|| anyhow!("missing \"steps\" list"))?;
-    h.write_u64(std::process::id() as u64);
+        let (mut inst, scratch) = self.start()?;
    h.finish() as u32
 }
 async fn run_file(
    broker: &Broker,
    id: &str,
    component: &Component,
    data: Option<&Path>,
    public: Option<&Path>,
    file: &Path,
 ) -> Result<()> {
    let text = std::fs::read_to_string(file)?;
    let (mut inst, scratch) = start(broker, id, component, data, public)?;
        let stderr = scratch.dir.join("stderr.log");
-    let mut sent = 0u32;
+        // Lines that the candidate wrote while a step was sent.
-    for (n, line) in text.lines().enumerate() {
+        let mut early = std::collections::VecDeque::new();
-        let line = line.trim();
+        for (n, step) in steps.iter().enumerate() {
-        if line.is_empty() || line.starts_with("//") {
+            let n = n + 1;
            continue;
        }
        let step: Value = serde_json::from_str(line).map_err(|e| anyhow!("line {}: invalid JSON: {e}", n + 1))?;
            if let Some(body) = step.get("send") {
-            sent += 1;
+                let from = step["from"].as_str().unwrap_or("test");
-            let from = step.get("from").and_then(Value::as_str).unwrap_or("test");
+                let env = json!({"id": format!("test/{n}"), "from": from, "body": body});
-            let env = json!({"id": format!("test/{sent}"), "from": from, "body": body});
+                inst.send_line(&env.to_string(), |line| early.push_back(line))
            inst.send_line(&env.to_string())
                    .await
-                .map_err(|e| anyhow!("line {}: candidate does not read stdin: {e}", n + 1))?;
+                    .map_err(|e| anyhow!("step {n}: candidate does not read stdin: {e}"))?;
-        } else if let Some(expected) = step.get("expect") {
+            }
-            let got = tokio::time::timeout(EXPECT_TIMEOUT, inst.stdout.recv()).await;
+            let expected = match step.get("expect") {
-            let got = match got {
+                None => vec![],
-                Err(_) => bail!("line {}: no message within {EXPECT_TIMEOUT:?}; expected {expected}", n + 1),
+                Some(Value::Array(list)) => list.clone(),
                Some(one) => vec![one.clone()],
            };
            for expected in expected {
                let next = async { if early.is_empty() { inst.stdout.recv().await } else { early.pop_front() } };
                let line = match tokio::time::timeout(EXPECT_TIMEOUT, next).await {
                    Err(_) => bail!("step {n}: no message within {EXPECT_TIMEOUT:?}; expected {expected}"),
                    Ok(None) => {
                        let exit = inst.wait().await;
-                    bail!("line {}: candidate ended ({exit}); expected {expected}. stderr:\n{}", n + 1, stderr_tail(&stderr))
+                        bail!("step {n}: candidate ended ({exit}); expected {expected}. stderr:\n{}", stderr_tail(&stderr))
                    }
                    Ok(Some(l)) => l,
                };
-            let msg: Value = serde_json::from_str(&got)
+                let msg: Value = serde_json::from_str(&line)
-                .map_err(|_| anyhow!("line {}: candidate wrote a non-JSON line: {}", n + 1, truncate(&got, 300)))?;
+                    .map_err(|_| anyhow!("step {n}: candidate wrote a non-JSON line: {}", truncate(&line, 300)))?;
-            let body = msg.get("body").cloned().unwrap_or(Value::Null);
+                if !subset_match(&expected, &msg["body"]) {
-            if !subset_match(expected, &body) {
+                    bail!("step {n}: expected body {expected}, got {}", truncate(&msg["body"].to_string(), 1000));
                bail!("line {}: expected body {expected}, got {}", n + 1, truncate(&body.to_string(), 1000));
                }
                if let Some(to) = step.get("to")
                    && msg.get("to") != Some(to)
                {
-                bail!("line {}: expected recipient {to}, got {}", n + 1, msg.get("to").cloned().unwrap_or(Value::Null));
+                    bail!("step {n}: expected recipient {to}, got {}", msg.get("to").unwrap_or(&Value::Null));
            }
        } else {
            bail!("line {}: use \"send\" or \"expect\"", n + 1);
                }
            }
-    inst.stop(&shutdown_line(), SHUTDOWN_DEADLINE).await;
+        }
        inst.stop(&shutdown_line(), SHUTDOWN_DEADLINE, |_| {}).await;
        Ok(())
    }
 }
@@ -6,22 +6,31 @@
 //!
 //! The broker knows nothing about Rust. This actor is one way to get a
 //! `.wasm` file. Other actors can add other languages.
 //!
 //! Actors depend on the SDK with `sausage-actor = "0.1"`. The SDK is not
 //! published: this actor copies the SDK of this host to `public/sdk/` (so
 //! that every actor can read it), and points the dependency there in the
 //! build copy of `Cargo.toml`.
 use std::path::{Path, PathBuf};
 use std::sync::Arc;
-use std::time::{Duration, Instant};
+use std::time::Instant;
 use anyhow::{Context, Result, anyhow, bail};
 use serde_json::{Value, json};
 use tokio::process::Command;
-use tokio::sync::{Mutex, mpsc};
+use tokio::sync::mpsc;
-use crate::broker::{Broker, Envelope, truncate};
+use include_dir::{Dir, include_dir};
 use crate::broker::{Broker, Envelope};
 use crate::world::{self, World};
 pub const ID: &str = "cargo";
 pub const TARGET: &str = "wasm32-wasip2";
-const BUILD_TIMEOUT: Duration = Duration::from_secs(900);
+
 /// The source of the `sausage-actor` SDK.
 static SDK: Dir<'_> = include_dir!("$CARGO_MANIFEST_DIR/../sdk");
 pub struct BuildOutput {
    /// Host path of the published `.wasm` file.
@@ -30,15 +39,16 @@ pub struct BuildOutput {
    pub warnings: String,
 }
 /// All builds share one target folder, so they run one at a time.
 pub struct Cargo {
    world: World,
    /// One build at a time: all builds share one target folder.
    lock: Mutex<()>,
 }
 impl Cargo {
-    pub fn new(world: World) -> Self {
+    /// Create the actor and install the SDK of this host into `public/sdk/`.
-        Self { world, lock: Mutex::new(()) }
+    pub fn new(world: World) -> Result<Self> {
        write_dir(&SDK, &world.public_dir(ID).join("sdk"))?;
        Ok(Self { world })
    }
    /// Build the crate in `source` (a host path) and publish the `.wasm` file
@@ -47,18 +57,12 @@ impl Cargo {
        if !source.join("Cargo.toml").is_file() {
            bail!("{} has no Cargo.toml", source.display());
        }
        let _guard = self.lock.lock().await;
        let started = Instant::now();
        let data = self.world.data_dir(ID);
-        let key = format!("{:016x}", fxhash(source.to_string_lossy().as_bytes()));
+        let build_dir = data.join("work");
-        let build_dir = data.join("work").join(&key);
+        world::replace_source(source, &build_dir)?;
        world::replace_tree(source, &build_dir)?;
        // The crate must not join a parent workspace by accident.
        let manifest = build_dir.join("Cargo.toml");
-        let text = std::fs::read_to_string(&manifest)?;
+        std::fs::write(&manifest, prepare_manifest(&std::fs::read_to_string(&manifest)?, Some(&self.world.public_dir(ID).join("sdk")))?)?;
        if !text.contains("[workspace]") {
            std::fs::write(&manifest, format!("{text}\n[workspace]\n"))?;
        }
        let mut cmd = Command::new("cargo");
        cmd.arg("build")
@@ -70,13 +74,10 @@ impl Cargo {
            .arg(data.join("target"))
            .current_dir(&build_dir)
            .kill_on_drop(true);
-        let out = tokio::time::timeout(BUILD_TIMEOUT, cmd.output())
+        let out = cmd.output().await.context("cannot run cargo (is it on PATH, with the wasm32-wasip2 target?)")?;
            .await
            .map_err(|_| anyhow!("cargo build took longer than {BUILD_TIMEOUT:?}"))?
            .context("cannot run cargo (is it on PATH, with the wasm32-wasip2 target?)")?;
        let stderr = String::from_utf8_lossy(&out.stderr).to_string();
        if !out.status.success() {
-            bail!("{}", truncate(&strip_progress(&stderr), 20_000));
+            bail!("{}", strip_progress(&stderr));
        }
        let mut artifact = None;
        for line in String::from_utf8_lossy(&out.stdout).lines() {
@@ -97,16 +98,17 @@ impl Cargo {
        Ok(BuildOutput { wasm: dest, seconds: started.elapsed().as_secs_f64(), warnings: strip_progress(&stderr) })
    }
-    pub async fn run_actor(self: Arc<Self>, broker: Arc<Broker>, mut mailbox: mpsc::Receiver<Envelope>) {
+    /// The native `cargo` actor. Builds run one at a time, in order.
    /// Replies (messages with `reply_to`) get no answer.
    pub async fn run_actor(self, broker: Arc<Broker>, mut mailbox: mpsc::Receiver<Envelope>) {
        while let Some(env) = mailbox.recv().await {
-            let this = self.clone();
+            if env.reply_to.is_some() {
-            let broker = broker.clone();
+                continue;
-            tokio::spawn(async move {
+            }
-                let body = this.handle(&broker, &env).await.unwrap_or_else(|e| {
+            let body = self.handle(&broker, &env).await.unwrap_or_else(|e| {
                json!({"type": "build_failed", "source": env.body.get("source"), "errors": format!("{e:#}")})
            });
            broker.send(ID, Some(&env.from), None, Some(&env.id), body);
            });
        }
    }
@@ -123,15 +125,55 @@ impl Cargo {
                    "source": source_s,
                    "built_by": ID,
                    "seconds": (out.seconds * 10.0).round() / 10.0,
-                    "warnings": truncate(&out.warnings, 4000),
+                    "warnings": out.warnings,
                }))
            }
            Some("shutdown") => Ok(json!({"type": "ignored"})),
            other => bail!("unknown request {other:?}. Known: build"),
        }
    }
 }
 /// Point a `sausage-actor` dependency at `sdk` (keeping its features), and
 /// add an empty `[workspace]`, so the crate never joins a parent workspace.
 fn prepare_manifest(text: &str, sdk: Option<&Path>) -> Result<String> {
    let mut doc: toml_edit::DocumentMut = text.parse()?;
    if let Some(sdk) = sdk {
        for section in ["dependencies", "dev-dependencies", "build-dependencies"] {
            let Some(dep) = doc.get_mut(section).and_then(|t| t.get_mut("sausage-actor")) else { continue };
            let mut table = dep.as_inline_table().cloned().unwrap_or_default();
            for key in ["version", "path", "git", "branch", "tag", "rev", "registry"] {
                table.remove(key);
            }
            table.insert("path", sdk.display().to_string().into());
            *dep = toml_edit::value(table);
        }
    }
    if doc.get("workspace").is_none() {
        doc["workspace"] = toml_edit::table();
    }
    Ok(doc.to_string())
 }
 /// Write the files of `dir` below `to`. Skip files that did not change, so
 /// that cargo does not rebuild the SDK at every start.
 fn write_dir(dir: &Dir<'_>, to: &Path) -> Result<()> {
    for file in dir.files() {
        let dest = to.join(file.path());
        let contents = match file.path().file_name() {
            Some(n) if n == "Cargo.toml" => prepare_manifest(file.contents_utf8().context("Cargo.toml")?, None)?.into_bytes(),
            _ => file.contents().to_vec(),
        };
        if std::fs::read(&dest).ok() != Some(contents.clone()) {
            std::fs::create_dir_all(dest.parent().context("no parent")?)?;
            std::fs::write(&dest, contents)?;
        }
    }
    for sub in dir.dirs() {
        write_dir(sub, to)?;
    }
    Ok(())
 }
 fn next_build_number(dir: &Path) -> Result<u64> {
    std::fs::create_dir_all(dir)?;
    let max = std::fs::read_dir(dir)?
@@ -158,12 +200,3 @@ fn strip_progress(stderr: &str) -> String {
        .collect::<Vec<_>>()
        .join("\n")
 }
 fn fxhash(bytes: &[u8]) -> u64 {
    let mut h: u64 = 0xcbf29ce484222325;
    for b in bytes {
        h ^= *b as u64;
        h = h.wrapping_mul(0x100000001b3);
    }
    h
 }
@@ -3,19 +3,13 @@
 //! - `@<actor> <json>` sends a JSON body. `@<actor> <text>` sends
 //!   `{"type": "text", "text": ...}`.
 //! - A line without `@` goes to `agent` as text.
-//! - `/deploy <actor> <folder>` builds a Rust folder with `cargo`, then spawns
+//! - `/help`, `/quit`. EOF on stdin also quits.
 //!   or upgrades the actor.
 //! - `/list`, `/sleep <seconds>`, `/help`, `/quit`.
-use std::collections::HashMap;
+use std::sync::Arc;
 use std::sync::atomic::{AtomicU64, Ordering};
 use std::sync::{Arc, Mutex};
 use std::time::Duration;
 use anyhow::{Result, anyhow, bail};
 use serde_json::{Value, json};
 use tokio::io::{AsyncBufReadExt, BufReader};
-use tokio::sync::{mpsc, oneshot};
+use tokio::sync::mpsc;
 use crate::broker::{Broker, Envelope};
@@ -25,183 +19,49 @@ const HELP: &str = "\
@<actor> <json>   send a JSON body to an actor
@<actor> <text>   send {\"type\":\"text\",\"text\":...}
 <text>            send text to the agent
 /deploy <actor> <dir>  build a Rust folder with cargo, then spawn or upgrade
 /list                  list actors
 /sleep <seconds>       wait (for scripts)
 /await <actor> <secs>  wait for the next message from an actor (for scripts)
 /quit             stop all actors and exit";
-pub struct Console {
+/// Print a message: text bodies as text, everything else as JSON.
    broker: Arc<Broker>,
    waiters: Mutex<HashMap<String, oneshot::Sender<Envelope>>>,
    seq: AtomicU64,
    /// Number of messages received per sender, for `/await`.
    seen: Mutex<HashMap<String, u64>>,
    arrived: tokio::sync::Notify,
 }
 fn show(env: &Envelope) {
    let reply = if env.reply_to.is_some() { " ↩" } else { "" };
-    let b = &env.body;
+    match env.body["text"].as_str() {
-    if b["type"] == "text"
+        Some(text) if env.body["type"] == "text" => println!("[{}{reply}] {text}", env.from),
-        && let Some(t) = b["text"].as_str()
+        _ => println!("[{}{reply}] {}", env.from, env.body),
    {
        println!("[{}{reply}] {t}", env.from);
        return;
    }
    let mut compact = b.clone();
    let mut extra = Vec::new();
    if let Some(obj) = compact.as_object_mut() {
        for key in ["errors", "warnings", "reason"] {
            if let Some(Value::String(s)) = obj.get(key)
                && s.contains('\n')
            {
                extra.push((key, s.clone()));
                obj.remove(key);
            }
        }
    }
    println!("[{}{reply}] {compact}", env.from);
    for (k, s) in extra {
        println!("  {k}:\n{}", s.lines().map(|l| format!("    {l}")).collect::<Vec<_>>().join("\n"));
    }
 }
-impl Console {
+/// Print every message that arrives for the console.
-    pub fn new(broker: Arc<Broker>) -> Arc<Self> {
+pub async fn run_mailbox(mut mailbox: mpsc::Receiver<Envelope>) {
        Arc::new(Self {
            broker,
            waiters: Mutex::new(HashMap::new()),
            seq: AtomicU64::new(1),
            seen: Mutex::new(HashMap::new()),
            arrived: tokio::sync::Notify::new(),
        })
    }
    pub async fn run_mailbox(self: Arc<Self>, mut mailbox: mpsc::Receiver<Envelope>) {
    while let Some(env) = mailbox.recv().await {
        show(&env);
            *self.seen.lock().unwrap().entry(env.from.clone()).or_default() += 1;
            self.arrived.notify_waiters();
            if let Some(r) = &env.reply_to
                && let Some(tx) = self.waiters.lock().unwrap().remove(r)
            {
                let _ = tx.send(env);
            }
        }
    }
 }
-    fn send(&self, to: &str, body: Value) -> String {
+/// Read lines until EOF or `/quit`, and send them as messages.
-        let own = format!("c{}", self.seq.fetch_add(1, Ordering::Relaxed));
+pub async fn run_input(broker: Arc<Broker>) {
        self.broker.send(ID, Some(to), Some(&own), None, body)
    }
    async fn request(&self, to: &str, body: Value, timeout: Duration) -> Result<Envelope> {
        let own = format!("c{}", self.seq.fetch_add(1, Ordering::Relaxed));
        let (tx, rx) = oneshot::channel();
        self.waiters.lock().unwrap().insert(format!("{ID}/{own}"), tx);
        self.broker.send(ID, Some(to), Some(&own), None, body);
        tokio::time::timeout(timeout, rx)
            .await
            .map_err(|_| anyhow!("no reply from {to} within {timeout:?}"))?
            .map_err(|_| anyhow!("reply channel closed"))
    }
    async fn deploy(&self, actor: &str, dir: &str) -> Result<()> {
        let path = std::path::absolute(dir)?;
        let source = path.display().to_string();
        println!("· building {source} …");
        let built = self.request(crate::cargo_actor::ID, json!({"type": "build", "source": source}), Duration::from_secs(900)).await?;
        if built.body["type"] != "built" {
            bail!("build failed");
        }
        let exists = self.broker.registry().actors.contains_key(actor);
        let ty = if exists { "upgrade" } else { "spawn" };
        println!("· {ty} {actor} …");
        let body = json!({
            "type": ty,
            "actor": actor,
            "wasm": built.body["wasm"],
            "source": source,
            "built_by": built.body["built_by"],
        });
        let r = self.request("broker", body, Duration::from_secs(300)).await?;
        if r.body["type"] == "error" {
            bail!("{ty} failed");
        }
        Ok(())
    }
    /// Read commands until EOF or `/quit`.
    pub async fn run_input(self: Arc<Self>) {
    println!("Sausage console. Type /help for commands.");
    let mut lines = BufReader::new(tokio::io::stdin()).lines();
    while let Ok(Some(line)) = lines.next_line().await {
        let line = line.trim();
-            if line.is_empty() || line.starts_with('#') {
+        let (to, body) = match line {
            "" => continue,
            "/quit" => break,
            "/help" => {
                println!("{HELP}");
                continue;
            }
-            if let Err(e) = self.command(line).await {
+            _ => match line.strip_prefix('@') {
-                if e.to_string() == "quit" {
+                Some(rest) => {
                    break;
                }
                println!("! {e:#}");
            }
        }
    }
    async fn command(&self, line: &str) -> Result<()> {
        if let Some(rest) = line.strip_prefix('@') {
                    let (to, text) = rest.split_once(char::is_whitespace).unwrap_or((rest, ""));
-            let text = text.trim();
+                    let body = match serde_json::from_str::<Value>(text.trim()) {
            let body = match serde_json::from_str::<Value>(text) {
                        Ok(v @ Value::Object(_)) => v,
-                _ => json!({"type": "text", "text": text}),
+                        _ => json!({"type": "text", "text": text.trim()}),
                    };
-            self.send(to, body);
+                    (to, body)
            return Ok(());
                }
-        if let Some(cmd) = line.strip_prefix('/') {
+                None => ("agent", json!({"type": "text", "text": line})),
-            let mut parts = cmd.split_whitespace();
+            },
            match parts.next() {
                Some("help") => println!("{HELP}"),
                Some("quit") => bail!("quit"),
                Some("list") => {
                    self.send("broker", json!({"type": "list"}));
                }
                Some("sleep") => {
                    let secs: f64 = parts.next().and_then(|s| s.parse().ok()).unwrap_or(1.0);
                    tokio::time::sleep(Duration::from_secs_f64(secs)).await;
                }
                Some("await") => {
                    let from = parts.next().unwrap_or("agent").to_string();
                    let secs: f64 = parts.next().and_then(|s| s.parse().ok()).unwrap_or(60.0);
                    let count = |c: &Self| c.seen.lock().unwrap().get(&from).copied().unwrap_or(0);
                    let before = count(self);
                    let deadline = tokio::time::Instant::now() + Duration::from_secs_f64(secs);
                    loop {
                        let notified = self.arrived.notified();
                        tokio::pin!(notified);
                        notified.as_mut().enable();
                        if count(self) != before {
                            break;
                        }
                        if tokio::time::timeout_at(deadline, notified).await.is_err() {
                            bail!("no message from {from} within {secs} s");
                        }
                    }
                }
                Some("deploy") => {
                    let (Some(actor), Some(dir)) = (parts.next(), parts.next()) else {
                        bail!("usage: /deploy <actor> <dir>");
        };
-                    self.deploy(actor, dir).await?;
+        broker.send(ID, Some(to), None, None, body);
                }
                _ => bail!("unknown command. Type /help."),
            }
            return Ok(());
        }
        self.send("agent", json!({"type": "text", "text": line}));
        Ok(())
    }
 }
@@ -1,434 +0,0 @@
 //! Filesystem layer with commit-on-close semantics.
 //!
 //! The layer wraps the wasmtime-wasi `wasi:filesystem` implementation. For
 //! mounts with `commit_on_close`, an open for write goes to a hidden temporary
 //! file next to the target. When the guest drops the descriptor (close), the
 //! layer renames the temporary file into place. Until then, no other reader
 //! sees the change. If the instance traps or is killed, the changes are lost.
 use std::collections::HashMap;
 use std::path::{Component, Path, PathBuf};
 use wasmtime::component::{HasData, Resource};
 use wasmtime_wasi::filesystem::{Descriptor, WasiFilesystemCtxView};
 use wasmtime_wasi::p2::bindings::filesystem::types::{
    self, ErrorCode, HostDescriptor, HostDirectoryEntryStream,
 };
 use wasmtime_wasi::p2::bindings::filesystem::preopens;
 use wasmtime_wasi::p2::{DynInputStream, DynOutputStream, FsError, FsResult};
 /// Name prefix of uncommitted files. The layer hides these names from guests.
 pub const TMP_PREFIX: &str = ".sausage-tmp-";
 #[derive(Clone, Debug)]
 pub struct Mount {
    pub guest: String,
    pub host: PathBuf,
    pub writable: bool,
 }
 #[derive(Clone)]
 struct DirInfo {
    host: PathBuf,
    root: PathBuf,
    commit: bool,
 }
 struct Pending {
    tmp: PathBuf,
    target: PathBuf,
 }
 /// Per-instance state of the layer.
 pub struct FsExt {
    mounts: Vec<Mount>,
    dirs: HashMap<u32, DirInfo>,
    pending: HashMap<u32, Pending>,
    counter: u64,
 }
 impl FsExt {
    pub fn new(mounts: Vec<Mount>) -> Self {
        Self { mounts, dirs: HashMap::new(), pending: HashMap::new(), counter: 0 }
    }
    /// Commit every open write. Use this when the guest exits normally,
    /// because process exit closes all files.
    pub fn commit_all(&mut self) {
        for (_, p) in self.pending.drain() {
            commit(p);
        }
    }
 }
 impl Drop for FsExt {
    /// Discard writes that were not committed (trap, kill).
    fn drop(&mut self) {
        for (_, p) in self.pending.drain() {
            let _ = std::fs::remove_file(&p.tmp);
        }
    }
 }
 fn commit(p: Pending) {
    if let Err(e) = std::fs::rename(&p.tmp, &p.target) {
        eprintln!("sausage: commit of {} failed: {e}", p.target.display());
        let _ = std::fs::remove_file(&p.tmp);
    }
 }
 fn is_tmp_name(path: &str) -> bool {
    path.rsplit('/').next().is_some_and(|n| n.starts_with(TMP_PREFIX))
 }
 /// Join `rel` to the directory `dir` lexically. Return `None` if the result
 /// leaves the mount root.
 fn resolve(dir: &DirInfo, rel: &str) -> Option<PathBuf> {
    let mut out = dir.host.clone();
    for c in Path::new(rel).components() {
        match c {
            Component::Normal(n) => out.push(n),
            Component::CurDir => {}
            Component::ParentDir => {
                if !out.pop() {
                    return None;
                }
            }
            Component::RootDir | Component::Prefix(_) => return None,
        }
    }
    out.starts_with(&dir.root).then_some(out)
 }
 fn io_err(e: std::io::Error) -> FsError {
    ErrorCode::from(e).into()
 }
 pub struct ActorFs<'a> {
    pub inner: WasiFilesystemCtxView<'a>,
    pub ext: &'a mut FsExt,
 }
 pub struct ActorFsData;
 impl HasData for ActorFsData {
    type Data<'a> = ActorFs<'a>;
 }
 impl preopens::Host for ActorFs<'_> {
    fn get_directories(&mut self) -> wasmtime::Result<Vec<(Resource<Descriptor>, String)>> {
        let dirs = preopens::Host::get_directories(&mut self.inner)?;
        for (r, name) in &dirs {
            if let Some(m) = self.ext.mounts.iter().find(|m| &m.guest == name) {
                self.ext.dirs.insert(
                    r.rep(),
                    DirInfo { host: m.host.clone(), root: m.host.clone(), commit: m.writable },
                );
            }
        }
        Ok(dirs)
    }
 }
 impl types::Host for ActorFs<'_> {
    fn convert_error_code(&mut self, err: FsError) -> wasmtime::Result<ErrorCode> {
        types::Host::convert_error_code(&mut self.inner, err)
    }
    fn filesystem_error_code(
        &mut self,
        err: Resource<wasmtime::Error>,
    ) -> wasmtime::Result<Option<ErrorCode>> {
        types::Host::filesystem_error_code(&mut self.inner, err)
    }
 }
 impl HostDescriptor for ActorFs<'_> {
    async fn advise(
        &mut self,
        fd: Resource<types::Descriptor>,
        offset: types::Filesize,
        len: types::Filesize,
        advice: types::Advice,
    ) -> FsResult<()> {
        HostDescriptor::advise(&mut self.inner, fd, offset, len, advice).await
    }
    async fn sync_data(&mut self, fd: Resource<types::Descriptor>) -> FsResult<()> {
        HostDescriptor::sync_data(&mut self.inner, fd).await
    }
    async fn get_flags(&mut self, fd: Resource<types::Descriptor>) -> FsResult<types::DescriptorFlags> {
        HostDescriptor::get_flags(&mut self.inner, fd).await
    }
    async fn get_type(&mut self, fd: Resource<types::Descriptor>) -> FsResult<types::DescriptorType> {
        HostDescriptor::get_type(&mut self.inner, fd).await
    }
    async fn set_size(&mut self, fd: Resource<types::Descriptor>, size: types::Filesize) -> FsResult<()> {
        HostDescriptor::set_size(&mut self.inner, fd, size).await
    }
    async fn set_times(
        &mut self,
        fd: Resource<types::Descriptor>,
        atim: types::NewTimestamp,
        mtim: types::NewTimestamp,
    ) -> FsResult<()> {
        HostDescriptor::set_times(&mut self.inner, fd, atim, mtim).await
    }
    async fn read(
        &mut self,
        fd: Resource<types::Descriptor>,
        len: types::Filesize,
        offset: types::Filesize,
    ) -> FsResult<(Vec<u8>, bool)> {
        HostDescriptor::read(&mut self.inner, fd, len, offset).await
    }
    async fn write(
        &mut self,
        fd: Resource<types::Descriptor>,
        buf: Vec<u8>,
        offset: types::Filesize,
    ) -> FsResult<types::Filesize> {
        HostDescriptor::write(&mut self.inner, fd, buf, offset).await
    }
    async fn read_directory(
        &mut self,
        fd: Resource<types::Descriptor>,
    ) -> FsResult<Resource<types::DirectoryEntryStream>> {
        HostDescriptor::read_directory(&mut self.inner, fd).await
    }
    async fn sync(&mut self, fd: Resource<types::Descriptor>) -> FsResult<()> {
        HostDescriptor::sync(&mut self.inner, fd).await
    }
    async fn create_directory_at(&mut self, fd: Resource<types::Descriptor>, path: String) -> FsResult<()> {
        HostDescriptor::create_directory_at(&mut self.inner, fd, path).await
    }
    async fn stat(&mut self, fd: Resource<types::Descriptor>) -> FsResult<types::DescriptorStat> {
        HostDescriptor::stat(&mut self.inner, fd).await
    }
    async fn stat_at(
        &mut self,
        fd: Resource<types::Descriptor>,
        path_flags: types::PathFlags,
        path: String,
    ) -> FsResult<types::DescriptorStat> {
        if is_tmp_name(&path) {
            return Err(ErrorCode::NoEntry.into());
        }
        HostDescriptor::stat_at(&mut self.inner, fd, path_flags, path).await
    }
    async fn set_times_at(
        &mut self,
        fd: Resource<types::Descriptor>,
        path_flags: types::PathFlags,
        path: String,
        atim: types::NewTimestamp,
        mtim: types::NewTimestamp,
    ) -> FsResult<()> {
        HostDescriptor::set_times_at(&mut self.inner, fd, path_flags, path, atim, mtim).await
    }
    async fn link_at(
        &mut self,
        fd: Resource<types::Descriptor>,
        old_path_flags: types::PathFlags,
        old_path: String,
        new_descriptor: Resource<types::Descriptor>,
        new_path: String,
    ) -> FsResult<()> {
        HostDescriptor::link_at(&mut self.inner, fd, old_path_flags, old_path, new_descriptor, new_path).await
    }
    async fn open_at(
        &mut self,
        fd: Resource<types::Descriptor>,
        path_flags: types::PathFlags,
        path: String,
        oflags: types::OpenFlags,
        flags: types::DescriptorFlags,
    ) -> FsResult<Resource<types::Descriptor>> {
        if is_tmp_name(&path) {
            return Err(ErrorCode::NoEntry.into());
        }
        let parent = self.ext.dirs.get(&fd.rep()).cloned();
        // Commit-on-close: redirect writes to a hidden temporary file.
        if let Some(dir) = parent.as_ref().filter(|d| d.commit)
            && flags.contains(types::DescriptorFlags::WRITE)
            && !oflags.contains(types::OpenFlags::DIRECTORY)
        {
            let target = resolve(dir, &path).ok_or(FsError::from(ErrorCode::NotPermitted))?;
            let meta = std::fs::metadata(&target).ok();
            if meta.as_ref().is_some_and(|m| m.is_dir()) {
                return Err(ErrorCode::IsDirectory.into());
            }
            let exists = meta.is_some();
            if exists && oflags.contains(types::OpenFlags::EXCLUSIVE) {
                return Err(ErrorCode::Exist.into());
            }
            if !exists && !oflags.contains(types::OpenFlags::CREATE) {
                return Err(ErrorCode::NoEntry.into());
            }
            let target_dir = target.parent().ok_or(FsError::from(ErrorCode::NotPermitted))?;
            if !target_dir.is_dir() {
                return Err(ErrorCode::NoEntry.into());
            }
            self.ext.counter += 1;
            let tmp_name = format!("{TMP_PREFIX}{}-{}", std::process::id(), self.ext.counter);
            let tmp_rel = match path.rsplit_once('/') {
                Some((d, _)) => format!("{d}/{tmp_name}"),
                None => tmp_name.clone(),
            };
            let tmp = target_dir.join(&tmp_name);
            let truncate = oflags.contains(types::OpenFlags::TRUNCATE);
            if exists && !truncate {
                std::fs::copy(&target, &tmp).map_err(io_err)?;
            }
            let oflags = (oflags | types::OpenFlags::CREATE)
                & !(types::OpenFlags::EXCLUSIVE | types::OpenFlags::TRUNCATE);
            return match HostDescriptor::open_at(&mut self.inner, fd, path_flags, tmp_rel, oflags, flags).await {
                Ok(r) => {
                    self.ext.pending.insert(r.rep(), Pending { tmp, target });
                    Ok(r)
                }
                Err(e) => {
                    let _ = std::fs::remove_file(&tmp);
                    Err(e)
                }
            };
        }
        let r = HostDescriptor::open_at(&mut self.inner, fd, path_flags, path.clone(), oflags, flags).await?;
        if let Some(dir) = parent
            && matches!(self.inner.table.get(&r)?, Descriptor::Dir(_))
            && let Some(host) = resolve(&dir, &path)
        {
            self.ext.dirs.insert(r.rep(), DirInfo { host, root: dir.root, commit: dir.commit });
        }
        Ok(r)
    }
    fn drop(&mut self, fd: Resource<types::Descriptor>) -> wasmtime::Result<()> {
        let rep = fd.rep();
        HostDescriptor::drop(&mut self.inner, fd)?;
        self.ext.dirs.remove(&rep);
        if let Some(p) = self.ext.pending.remove(&rep) {
            commit(p);
        }
        Ok(())
    }
    async fn readlink_at(&mut self, fd: Resource<types::Descriptor>, path: String) -> FsResult<String> {
        HostDescriptor::readlink_at(&mut self.inner, fd, path).await
    }
    async fn remove_directory_at(&mut self, fd: Resource<types::Descriptor>, path: String) -> FsResult<()> {
        HostDescriptor::remove_directory_at(&mut self.inner, fd, path).await
    }
    async fn rename_at(
        &mut self,
        fd: Resource<types::Descriptor>,
        old_path: String,
        new_fd: Resource<types::Descriptor>,
        new_path: String,
    ) -> FsResult<()> {
        if is_tmp_name(&old_path) || is_tmp_name(&new_path) {
            return Err(ErrorCode::NoEntry.into());
        }
        HostDescriptor::rename_at(&mut self.inner, fd, old_path, new_fd, new_path).await
    }
    async fn symlink_at(
        &mut self,
        _fd: Resource<types::Descriptor>,
        _src_path: String,
        _dest_path: String,
    ) -> FsResult<()> {
        // Symlinks would break the lexical path tracking of commit-on-close.
        Err(ErrorCode::NotPermitted.into())
    }
    async fn unlink_file_at(&mut self, fd: Resource<types::Descriptor>, path: String) -> FsResult<()> {
        if is_tmp_name(&path) {
            return Err(ErrorCode::NoEntry.into());
        }
        HostDescriptor::unlink_file_at(&mut self.inner, fd, path).await
    }
    fn read_via_stream(
        &mut self,
        fd: Resource<types::Descriptor>,
        offset: types::Filesize,
    ) -> FsResult<Resource<DynInputStream>> {
        HostDescriptor::read_via_stream(&mut self.inner, fd, offset)
    }
    fn write_via_stream(
        &mut self,
        fd: Resource<types::Descriptor>,
        offset: types::Filesize,
    ) -> FsResult<Resource<DynOutputStream>> {
        HostDescriptor::write_via_stream(&mut self.inner, fd, offset)
    }
    fn append_via_stream(&mut self, fd: Resource<types::Descriptor>) -> FsResult<Resource<DynOutputStream>> {
        HostDescriptor::append_via_stream(&mut self.inner, fd)
    }
    async fn is_same_object(
        &mut self,
        a: Resource<types::Descriptor>,
        b: Resource<types::Descriptor>,
    ) -> wasmtime::Result<bool> {
        HostDescriptor::is_same_object(&mut self.inner, a, b).await
    }
    async fn metadata_hash(&mut self, fd: Resource<types::Descriptor>) -> FsResult<types::MetadataHashValue> {
        HostDescriptor::metadata_hash(&mut self.inner, fd).await
    }
    async fn metadata_hash_at(
        &mut self,
        fd: Resource<types::Descriptor>,
        path_flags: types::PathFlags,
        path: String,
    ) -> FsResult<types::MetadataHashValue> {
        HostDescriptor::metadata_hash_at(&mut self.inner, fd, path_flags, path).await
    }
 }
 impl HostDirectoryEntryStream for ActorFs<'_> {
    async fn read_directory_entry(
        &mut self,
        stream: Resource<types::DirectoryEntryStream>,
    ) -> FsResult<Option<types::DirectoryEntry>> {
        let rep = stream.rep();
        loop {
            let entry = HostDirectoryEntryStream::read_directory_entry(
                &mut self.inner,
                Resource::new_borrow(rep),
            )
            .await?;
            match entry {
                Some(e) if e.name.starts_with(TMP_PREFIX) => continue,
                other => return Ok(other),
            }
        }
    }
    fn drop(&mut self, stream: Resource<types::DirectoryEntryStream>) -> wasmtime::Result<()> {
        HostDirectoryEntryStream::drop(&mut self.inner, stream)
    }
 }
@@ -0,0 +1,78 @@
 //! Sausage: grow a system of WASI actors by talking to it.
 //!
 //! The host runs the broker, the native actors (`broker`, `cargo`, and the
 //! console), and one supervisor per WASM actor. See `PROTOCOL.md`.
 pub mod broker;
 pub mod candidate;
 pub mod cargo_actor;
 pub mod console;
 pub mod runtime;
 pub mod supervisor;
 pub mod vfs;
 pub mod world;
 use std::path::Path;
 use std::sync::Arc;
 use anyhow::{Result, bail};
 use tokio::sync::mpsc;
 pub use broker::{Broker, Envelope};
 pub use world::World;
 /// The contract between the host and the actors. The host publishes it at
 /// `/actor/broker/public/PROTOCOL.md`, so that every actor can read it.
 const PROTOCOL: &str = include_str!("../../PROTOCOL.md");
 /// A running world.
 pub struct Host {
    pub world: World,
    pub broker: Arc<Broker>,
    native: Vec<tokio::task::JoinHandle<()>>,
    _lock: std::fs::File,
 }
 impl Host {
    /// Start the broker, `cargo`, and every registered actor of the world at
    /// `root`. Only one host can run a world at a time.
    pub async fn start(root: &Path) -> Result<Host> {
        let world = World::new(std::path::absolute(root)?);
        if !world.exists() {
            bail!("{} is not a Sausage world. Create one with: sausage init", root.display());
        }
        let lock = std::fs::File::create(world.root.join(".lock"))?;
        if lock.try_lock().is_err() {
            bail!("another sausage process runs {}", root.display());
        }
        let broker = Broker::new(world.clone(), runtime::Runtime::new()?)?;
        world::write_atomic(&world.public_dir("broker").join("PROTOCOL.md"), PROTOCOL.as_bytes())?;
        let cargo = cargo_actor::Cargo::new(world.clone())?;
        let native = vec![
            tokio::spawn(broker.clone().run_actor(broker.open_mailbox("broker"))),
            tokio::spawn(cargo.run_actor(broker.clone(), broker.open_mailbox(cargo_actor::ID))),
        ];
        for change in broker.scan().await {
            eprintln!("sausage: {change}");
        }
        Ok(Host { world, broker, native, _lock: lock })
    }
    /// Register a native actor with the ID `id` and return its mailbox.
    pub fn mailbox(&self, id: &str) -> mpsc::Receiver<Envelope> {
        self.broker.open_mailbox(id)
    }
    /// Stop the broker and `cargo` (with the requests they still run), then
    /// every actor, gracefully.
    pub async fn stop(self) {
        for task in &self.native {
            task.abort();
        }
        for task in self.native {
            let _ = task.await;
        }
        self.broker.shutdown_all().await;
    }
 }
@@ -1,24 +1,13 @@
 //! Sausage: grow a system of WASI actors by talking to it.
 mod broker;
 mod candidate;
 mod cargo_actor;
 mod console;
 mod fs;
 mod runtime;
 mod world;
 use std::io::Write;
 use std::path::PathBuf;
 use std::sync::Arc;
 use anyhow::{Context, Result, bail};
 use clap::{Parser, Subcommand};
 use include_dir::{Dir, include_dir};
 use serde_json::json;
-use crate::broker::Broker;
+use sausage::world::{ActorMeta, World};
-use crate::world::{NATIVE, Registry, VersionMeta, World};
+use sausage::{Host, cargo_actor, console};
 /// The source of the agent actor. `init` builds it like any other actor.
 static AGENT_SOURCE: Dir<'_> = include_dir!("$CARGO_MANIFEST_DIR/../agent");
@@ -33,19 +22,13 @@ struct Cli {
 #[derive(Subcommand)]
 enum Cmd {
    /// Create a new world and build the agent actor.
    ///
    /// Reads SAUSAGE_API, SAUSAGE_BASE_URL, SAUSAGE_MODEL and
    /// SAUSAGE_API_TOKEN, and asks for every value that is missing.
    Init {
        /// Folder of the new world.
        #[arg(default_value = "world")]
        dir: PathBuf,
        /// API shape: `openai-responses` or `anthropic-messages`.
        #[arg(long)]
        api: Option<String>,
        /// Base URL of the inference API (for example `https://api.openai.com`).
        #[arg(long)]
        base_url: Option<String>,
        /// Model ID.
        #[arg(long)]
        model: Option<String>,
    },
    /// Start the broker, all actors, and the console.
    Run {
@@ -54,7 +37,13 @@ enum Cmd {
    },
 }
-fn prompt(question: &str, default: Option<&str>) -> Result<String> {
+/// The value of `var`, or the answer to `question`.
 fn setting(var: &str, question: &str, default: Option<&str>) -> Result<String> {
    if let Ok(v) = std::env::var(var)
        && !v.is_empty()
    {
        return Ok(v);
    }
    match default {
        Some(d) => print!("{question} [{d}]: "),
        None => print!("{question}: "),
@@ -62,123 +51,68 @@ fn prompt(question: &str, default: Option<&str>) -> Result<String> {
    std::io::stdout().flush()?;
    let mut line = String::new();
    std::io::stdin().read_line(&mut line)?;
-    let v = line.trim().to_string();
+    match (line.trim(), default) {
-    match (v.is_empty(), default) {
+        ("", Some(d)) => Ok(d.to_string()),
-        (true, Some(d)) => Ok(d.to_string()),
+        ("", None) => bail!("{question} is required (or set {var})"),
-        (true, None) => bail!("{question} is required"),
+        (v, _) => Ok(v.to_string()),
        _ => Ok(v),
    }
 }
-async fn init(dir: PathBuf, api: Option<String>, base_url: Option<String>, model: Option<String>) -> Result<()> {
+async fn init(dir: PathBuf) -> Result<()> {
-    let world = World::new(std::path::absolute(&dir)?);
+    let api = setting("SAUSAGE_API", "API shape (openai-responses or anthropic-messages)", Some("openai-responses"))?;
    if world.exists() {
        bail!("{} is already a Sausage world", dir.display());
    }
    let api = match api {
        Some(a) => a,
        None => prompt("API shape (openai-responses or anthropic-messages)", Some("openai-responses"))?,
    };
    if api != "openai-responses" && api != "anthropic-messages" {
        bail!("unknown API shape {api:?}");
    }
-    let base_url = match base_url {
+    let base_url = setting("SAUSAGE_BASE_URL", "API base URL", None)?;
-        Some(u) => u,
+    let model = setting("SAUSAGE_MODEL", "Model", None)?;
-        None => prompt("API base URL", None)?,
+    let token = setting("SAUSAGE_API_TOKEN", "API token", None)?;
    };
    let model = match model {
        Some(m) => m,
        None => prompt("Model", None)?,
    };
    let token = match std::env::var("SAUSAGE_API_TOKEN") {
        Ok(t) if !t.is_empty() => t,
        _ => prompt("API token", None)?,
    };
-    std::fs::create_dir_all(&world.root)?;
+    let world = World::create(&dir)?;
-    let mut reg = Registry::default();
+    let console = ActorMeta { subscriptions: ["agent".to_string()].into(), ..world.read_meta(console::ID) };
-    reg.subscriptions.entry("agent".into()).or_default().insert("console".into());
+    world.write_meta(console::ID, &console)?;
    world.save_registry(&reg)?;
    for id in NATIVE {
        world.ensure_actor_dirs(id)?;
        world::write_atomic(
            &world.actor_dir(id).join("status.json"),
            serde_json::to_string_pretty(&json!({"id": id, "kind": "native", "state": "built-in"}))?.as_bytes(),
        )?;
    }
-    // The agent's private configuration. Only the agent can read /data.
+    // The agent's configuration, in its /data.
    world.ensure_actor_dirs("agent")?;
    let config = json!({"api": api, "base_url": base_url.trim_end_matches('/'), "model": model, "token": token});
    let config_path = world.data_dir("agent").join("config.json");
    std::fs::write(&config_path, serde_json::to_string_pretty(&config)?)?;
    #[cfg(unix)]
    {
        use std::os::unix::fs::PermissionsExt;
        std::fs::set_permissions(&config_path, std::fs::Permissions::from_mode(0o600))?;
    }
-    // Build the agent with the same path as every other Rust actor.
+    // The agent is an ordinary actor folder: `run` finds its `actor.wasm`,
-    let source = world.root.join("broker").join("seed").join("agent");
+    // tests it, and installs it as version 1.
    let source = world.source_dir("agent");
    std::fs::create_dir_all(&source)?;
    AGENT_SOURCE.extract(&source).context("extract agent source")?;
    println!("Building the agent actor (the first build takes a few minutes) …");
-    let cargo = cargo_actor::Cargo::new(world.clone());
+    let out = cargo_actor::Cargo::new(world.clone())?.build(&source).await.context("build agent")?;
-    let out = cargo.build(&source).await.context("build agent")?;
+    std::fs::copy(&out.wasm, world.wasm_path("agent"))?;
-    println!("Built in {:.1} s.", out.seconds);
+    println!("Built in {:.1} s. Start the world with: sausage run {}", out.seconds, dir.display());
    let runtime = runtime::Runtime::new()?;
    let broker = Broker::new(world.clone(), runtime)?;
    let meta = VersionMeta {
        version: 1,
        wasm: world.global_path(&out.wasm).unwrap_or_default(),
        source: Some(source.display().to_string()),
        built_by: Some(cargo_actor::ID.into()),
        requested_by: "init".into(),
        created_at: world::now(),
    };
    broker.create_actor("agent", &out.wasm, Some(&source), meta, false).await?;
    println!("World ready at {}. Start it with: sausage run {}", world.root.display(), dir.display());
    Ok(())
 }
 async fn run(dir: PathBuf) -> Result<()> {
-    let world = World::new(std::path::absolute(&dir)?);
+    let host = Host::start(&dir).await?;
-    if !world.exists() {
+    tokio::spawn(console::run_mailbox(host.mailbox(console::ID)));
-        bail!("{} is not a Sausage world. Create one with: sausage init {}", dir.display(), dir.display());
+    let broker = host.broker.clone();
-    }
+    let exit = tokio::select! {
-    // One host process per world.
+        _ = console::run_input(host.broker.clone()) => false,
-    let lock = std::fs::File::create(world.root.join(".lock"))?;
+        _ = broker.exit_requested() => true,
-    if lock.try_lock().is_err() {
+    };
        bail!("another sausage process runs {}", dir.display());
    }
    let runtime = runtime::Runtime::new()?;
    let broker = Broker::new(world.clone(), runtime)?;
    let rx = broker.open_mailbox("broker");
    tokio::spawn(broker.clone().run_actor(rx));
    let rx = broker.open_mailbox(cargo_actor::ID);
    let cargo = Arc::new(cargo_actor::Cargo::new(world.clone()));
    tokio::spawn(cargo.run_actor(broker.clone(), rx));
    let rx = broker.open_mailbox(console::ID);
    let console = console::Console::new(broker.clone());
    tokio::spawn(console.clone().run_mailbox(rx));
    broker.start_all();
    console.run_input().await;
    println!("Stopping actors …");
-    broker.shutdown_all().await;
+    host.stop().await;
-    drop(lock);
+    if exit {
        // The console still blocks on a stdin read that cannot be cancelled,
        // so the runtime would not shut down on its own. Exit code 75 tells
        // `nix run .#loop` to start the host again (0 = /quit = stop the loop).
        println!("Exiting, as an actor asked the broker to.");
        std::process::exit(75);
    }
    Ok(())
 }
 #[tokio::main]
 async fn main() -> Result<()> {
-    let cli = Cli::parse();
+    match Cli::parse().command {
-    match cli.command {
+        Cmd::Init { dir } => init(dir).await,
        Cmd::Init { dir, api, base_url, model } => init(dir, api, base_url, model).await,
        Cmd::Run { dir } => run(dir).await,
    }
 }
@@ -4,7 +4,7 @@
 //! NDJSON lines to its stdin and reads NDJSON lines from its stdout.
 use std::path::{Path, PathBuf};
-use std::sync::Arc;
+use std::sync::{Arc, Weak};
 use std::time::Duration;
 use anyhow::{Context, Result};
@@ -14,22 +14,21 @@ use tokio::task::JoinHandle;
 use wasmtime::component::{Component, Linker, ResourceTable};
 use wasmtime::{Config, Engine, Store};
 use wasmtime_wasi::cli::{AsyncStdinStream, AsyncStdoutStream};
 use wasmtime_wasi::filesystem::WasiFilesystemCtxView;
 use wasmtime_wasi::p2::bindings::Command;
-use wasmtime_wasi::p2::bindings::filesystem::{preopens, types};
+use wasmtime_wasi::p2::bindings::filesystem;
 use wasmtime_wasi::{FsPerms, I32Exit, WasiCtx, WasiCtxView, WasiView};
 use wasmtime_wasi_http::{WasiHttpCtx, WasiHttpCtxView, WasiHttpHooks, WasiHttpView};
-use crate::fs::{ActorFs, ActorFsData, FsExt, Mount};
+use crate::broker::Broker;
 use crate::vfs::{Vfs, VfsState, VfsView};
-pub struct WasiPart {
+/// A host folder that the guest sees at `guest`.
-    ctx: WasiCtx,
+#[derive(Clone, Debug)]
-    table: ResourceTable,
+pub struct Mount {
-}
+    pub guest: String,
-
+    pub host: PathBuf,
-impl WasiView for WasiPart {
+    pub writable: bool,
    fn ctx(&mut self) -> WasiCtxView<'_> {
        WasiCtxView { ctx: &mut self.ctx, table: &mut self.table }
    }
 }
 pub struct HttpHooks {
@@ -67,28 +66,26 @@ impl WasiHttpHooks for HttpHooks {
 }
 pub struct ActorState {
-    wasi: WasiPart,
+    ctx: WasiCtx,
-    fsx: FsExt,
+    table: ResourceTable,
    http: WasiHttpCtx,
    hooks: HttpHooks,
    vfs: VfsState,
 }
 fn vfs_view(s: &mut ActorState) -> VfsView<'_> {
    VfsView { inner: WasiFilesystemCtxView { ctx: s.ctx.filesystem(), table: &mut s.table }, state: &mut s.vfs }
 }
 impl WasiView for ActorState {
    fn ctx(&mut self) -> WasiCtxView<'_> {
-        self.wasi.ctx()
+        WasiCtxView { ctx: &mut self.ctx, table: &mut self.table }
    }
 }
 impl WasiHttpView for ActorState {
    fn http(&mut self) -> WasiHttpCtxView<'_> {
-        WasiHttpCtxView { ctx: &mut self.http, table: &mut self.wasi.table, hooks: &mut self.hooks }
+        WasiHttpCtxView { ctx: &mut self.http, table: &mut self.table, hooks: &mut self.hooks }
    }
 }
 fn actor_fs(s: &mut ActorState) -> ActorFs<'_> {
    ActorFs {
        inner: wasmtime_wasi::filesystem::WasiFilesystemView::filesystem(&mut s.wasi),
        ext: &mut s.fsx,
    }
 }
@@ -108,12 +105,6 @@ pub enum Exit {
    Trap(String),
 }
 impl Exit {
    pub fn is_clean(&self) -> bool {
        matches!(self, Exit::Clean)
    }
 }
 impl std::fmt::Display for Exit {
    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
        match self {
@@ -126,24 +117,52 @@ impl std::fmt::Display for Exit {
 pub struct InstanceConfig {
    pub mounts: Vec<Mount>,
-    pub allow_http: bool,
+    /// Outgoing HTTP, and TCP, UDP, and DNS through `wasi:sockets`.
    pub network: bool,
    pub stderr_log: PathBuf,
    pub env: Vec<(String, String)>,
    /// The actor that runs in the instance.
    pub actor: String,
    /// Asks the actors that serve `/actor/<id>/fs/` (see `vfs.rs`).
    pub broker: Weak<Broker>,
 }
 /// A running guest. Dropping it kills the guest.
 pub struct Instance {
-    stdin: DuplexStream,
+    stdin: Option<DuplexStream>,
    /// Lines that the guest writes to stdout. Closed when the guest ends.
    pub stdout: mpsc::Receiver<String>,
    task: JoinHandle<Exit>,
 }
 impl Drop for Instance {
    fn drop(&mut self) {
        self.task.abort();
    }
 }
 impl Instance {
-    /// Write one line to the guest's stdin.
+    /// Write one line to the guest's stdin, in one write. Meanwhile, pass the
-    pub async fn send_line(&mut self, line: &str) -> std::io::Result<()> {
+    /// lines that the guest writes to `route`: a guest that blocks on a full
-        self.stdin.write_all(line.as_bytes()).await?;
+    /// stdout would never read its stdin.
-        self.stdin.write_all(b"\n").await?;
+    pub async fn send_line(&mut self, line: &str, mut route: impl FnMut(String)) -> std::io::Result<()> {
-        self.stdin.flush().await
+        let stdin = self.stdin.as_mut().ok_or(std::io::ErrorKind::BrokenPipe)?;
        let bytes = format!("{line}\n");
        let write = async {
            stdin.write_all(bytes.as_bytes()).await?;
            stdin.flush().await
        };
        tokio::pin!(write);
        let mut open = true;
        loop {
            tokio::select! {
                done = &mut write => return done,
                out = self.stdout.recv(), if open => match out {
                    Some(out) => route(out),
                    None => open = false,
                },
            }
        }
    }
    /// Wait until the guest ends.
@@ -159,19 +178,35 @@ impl Instance {
        self.task.is_finished()
    }
-    /// Send `shutdown`, close stdin, and wait. Kill the guest after `deadline`.
+    /// Kill the guest. Its stdout closes when it has ended.
-    pub async fn stop(mut self, shutdown_line: &str, deadline: Duration) -> Exit {
+    pub fn kill(&self) {
        let _ = self.send_line(shutdown_line).await;
        let _ = self.stdin.shutdown().await;
        drop(self.stdin);
        match tokio::time::timeout(deadline, &mut self.task).await {
            Ok(Ok(exit)) => exit,
            Ok(Err(e)) => Exit::Trap(format!("host task failed: {e}")),
            Err(_) => {
        self.task.abort();
                let _ = (&mut self.task).await;
                Exit::Trap("killed after shutdown deadline".into())
    }
    /// Send `shutdown_line`, close stdin, and wait until the guest ends.
    /// Pass every line that the guest writes meanwhile to `route`. Kill the
    /// guest when `deadline` has passed.
    pub async fn stop(mut self, shutdown_line: &str, deadline: Duration, mut route: impl FnMut(String)) -> Exit {
        let stdin = self.stdin.take();
        let stdout = &mut self.stdout;
        let finished = tokio::time::timeout(deadline, async {
            let close = async {
                if let Some(mut stdin) = stdin {
                    let _ = stdin.write_all(format!("{shutdown_line}\n").as_bytes()).await;
                    let _ = stdin.shutdown().await;
                }
            };
            let drain = async {
                while let Some(line) = stdout.recv().await {
                    route(line);
                }
            };
            tokio::join!(close, drain);
        })
        .await;
        match finished {
            Ok(()) => self.wait().await,
            Err(_) => Exit::Trap("killed after shutdown deadline".into()),
        }
    }
 }
@@ -203,10 +238,10 @@ impl Runtime {
        let mut linker: Linker<ActorState> = Linker::new(&engine);
        wasmtime_wasi::p2::add_to_linker_async(&mut linker)?;
        wasmtime_wasi_http::p2::add_only_http_to_linker_async(&mut linker)?;
-        // Replace the filesystem with the commit-on-close layer.
+        // Replace `wasi:filesystem` with the wrapper that serves `/actor/<id>/fs/`.
        linker.allow_shadowing(true);
-        types::add_to_linker::<ActorState, ActorFsData>(&mut linker, actor_fs)?;
+        filesystem::types::add_to_linker::<ActorState, Vfs>(&mut linker, vfs_view)?;
-        preopens::add_to_linker::<ActorState, ActorFsData>(&mut linker, actor_fs)?;
+        filesystem::preopens::add_to_linker::<ActorState, Vfs>(&mut linker, vfs_view)?;
        linker.allow_shadowing(false);
        // Time slices: every 10 ms each running guest yields to the scheduler.
@@ -238,6 +273,9 @@ impl Runtime {
            .with_context(|| format!("open {}", cfg.stderr_log.display()))?;
        let mut b = WasiCtx::builder();
        if cfg.network {
            b.inherit_network().allow_tcp(true).allow_udp(true).allow_ip_name_lookup(true);
        }
        b.stdin(AsyncStdinStream::new(guest_in));
        b.stdout(AsyncStdoutStream::new(8192, guest_out));
        b.stderr(AsyncStdoutStream::new(8192, tokio::fs::File::from_std(stderr)));
@@ -251,10 +289,11 @@ impl Runtime {
                .with_context(|| format!("mount {} at {}", m.host.display(), m.guest))?;
        }
        let state = ActorState {
-            wasi: WasiPart { ctx: b.build(), table: ResourceTable::new() },
+            ctx: b.build(),
-            fsx: FsExt::new(cfg.mounts),
+            table: ResourceTable::new(),
            http: WasiHttpCtx::new(),
-            hooks: HttpHooks { allow: cfg.allow_http },
+            hooks: HttpHooks { allow: cfg.network },
            vfs: VfsState::new(cfg.broker.clone(), cfg.actor.clone()),
        };
        let (line_tx, line_rx) = mpsc::channel(1024);
@@ -278,7 +317,7 @@ impl Runtime {
                cmd.wasi_cli_run().call_run(&mut store).await
            }
            .await;
-            let exit = match result {
+            match result {
                Ok(Ok(())) => Exit::Clean,
                Ok(Err(())) => Exit::Code(1),
                Err(e) => match e.downcast_ref::<I32Exit>() {
@@ -291,14 +330,9 @@ impl Runtime {
                        Exit::Trap(short_trap(&full))
                    }
                },
            };
            // Process exit closes every file, so a clean exit commits.
            if exit.is_clean() {
                store.data_mut().fsx.commit_all();
            }
            exit
        });
-        Ok(Instance { stdin: host_in, stdout: line_rx, task })
+        Ok(Instance { stdin: Some(host_in), stdout: line_rx, task })
    }
 }
@@ -0,0 +1,287 @@
 //! The supervisor of one WASM actor: it runs the instance, feeds it the
 //! mailbox, routes its output, restarts it after a crash, and swaps versions.
 //!
 //! The broker talks to a supervisor only through `Control` requests.
 use std::sync::Arc;
 use std::time::{Duration, Instant};
 use anyhow::{Result, bail};
 use serde_json::{Value, json};
 use tokio::sync::{mpsc, oneshot};
 use wasmtime::component::Component;
 use crate::broker::{Broker, Envelope, SHUTDOWN_DEADLINE, shutdown_line};
 use crate::runtime::{Exit, Instance};
 /// A new version that crashes this often within `CRASH_WINDOW` after an
 /// upgrade is rolled back automatically.
 const CRASH_LIMIT: usize = 3;
 const CRASH_WINDOW: Duration = Duration::from_secs(30);
 pub type Reply = oneshot::Sender<Result<Value>>;
 pub enum Control {
    /// Swap to `version` (already in `versions/`, compiled as `component`).
    Upgrade { version: u64, component: Component, requester: String, reply: Reply },
    Rollback { version: u64, reply: Reply },
    Stop { reply: Reply },
    Start { reply: Reply },
    Shutdown { reply: Reply },
 }
 /// The time after an upgrade in which crashes count toward a rollback.
 struct Probation {
    previous: u64,
    since: Instant,
    crashes: usize,
    requester: String,
 }
 pub struct Supervisor {
    broker: Arc<Broker>,
    id: String,
    version: u64,
    running: bool,
    mailbox: mpsc::Receiver<Envelope>,
    control: mpsc::Receiver<Control>,
    component: Option<Component>,
    instance: Option<Instance>,
    started_at: Instant,
    restarts: u32,
    restart_at: Option<Instant>,
    probation: Option<Probation>,
    /// A control request that arrived during a blocked delivery.
    next_control: Option<Control>,
 }
 async fn next_line(instance: &mut Option<Instance>) -> Option<String> {
    match instance {
        Some(i) => i.stdout.recv().await,
        None => std::future::pending().await,
    }
 }
 async fn sleep_until(t: Option<Instant>) {
    match t {
        Some(t) => tokio::time::sleep_until(t.into()).await,
        None => std::future::pending().await,
    }
 }
 impl Supervisor {
    pub fn new(
        broker: Arc<Broker>,
        id: String,
        version: u64,
        running: bool,
        mailbox: mpsc::Receiver<Envelope>,
        control: mpsc::Receiver<Control>,
    ) -> Self {
        Self {
            broker,
            id,
            version,
            running,
            mailbox,
            control,
            component: None,
            instance: None,
            started_at: Instant::now(),
            restarts: 0,
            restart_at: None,
            probation: None,
            next_control: None,
        }
    }
    pub async fn run(mut self) {
        loop {
            if let Some(ctl) = self.next_control.take() {
                if self.handle(ctl).await {
                    break;
                }
                continue;
            }
            if self.running && self.instance.is_none() && self.restart_at.is_none_or(|t| Instant::now() >= t) {
                self.restart_at = None;
                let _ = self.start().await;
            }
            let has_instance = self.instance.is_some();
            tokio::select! {
                ctl = self.control.recv() => {
                    let Some(ctl) = ctl else { break };
                    if self.handle(ctl).await {
                        break;
                    }
                }
                msg = self.mailbox.recv(), if has_instance => {
                    let Some(msg) = msg else { break };
                    self.deliver(msg).await;
                }
                line = next_line(&mut self.instance) => match line {
                    Some(line) => self.broker.route_line(&self.id, &line),
                    None => {
                        let exit = self.instance.as_mut().unwrap().wait().await;
                        self.instance = None;
                        self.on_exit(exit).await;
                    }
                },
                _ = sleep_until(self.restart_at), if !has_instance && self.running => {}
            }
        }
    }
    /// Write a message to the instance's stdin, and route its output
    /// meanwhile. If a control request arrives before the actor reads the
    /// message, the instance is killed (a partly written line would corrupt
    /// the next message) and the request runs.
    async fn deliver(&mut self, msg: Envelope) {
        let Some(inst) = self.instance.as_mut() else { return };
        let (broker, id, line) = (self.broker.clone(), self.id.clone(), msg.to_line());
        let stuck = tokio::select! {
            written = inst.send_line(&line, |l| broker.route_line(&id, &l)) => match written {
                Ok(()) => return,
                // The instance is ending. The main loop sees its closed stdout.
                Err(_) => false,
            },
            Some(ctl) = self.control.recv() => {
                self.next_control = Some(ctl);
                true
            }
        };
        if msg.from != "broker" {
            let body = json!({"type": "undeliverable", "reason": "the actor stopped", "to": self.id});
            self.broker.send("broker", Some(&msg.from), None, Some(&msg.id), body);
        }
        if stuck && let Some(inst) = &self.instance {
            self.broker.log(&self.id, "killed: it did not read stdin when the broker needed it");
            inst.kill();
        }
    }
    /// Start an instance of the current version. If that fails, the actor
    /// stays stopped until the next start, upgrade, or rollback.
    async fn start(&mut self) -> Result<()> {
        let started = self.try_start();
        match &started {
            Ok(()) => self.started_at = Instant::now(),
            Err(e) => {
                self.broker.log(&self.id, &format!("cannot start version {}: {e:#}", self.version));
                self.running = false;
            }
        }
        started
    }
    fn try_start(&mut self) -> Result<()> {
        if self.component.is_none() {
            self.component = Some(self.broker.load_version(&self.id, self.version)?);
        }
        let cfg = self.broker.instance_config(&self.id, self.version, None);
        self.instance = Some(self.broker.runtime.start(self.component.as_ref().unwrap(), cfg)?);
        Ok(())
    }
    /// Stop the instance gracefully. Its last messages still get routed.
    async fn stop(&mut self) {
        let Some(inst) = self.instance.take() else { return };
        let (broker, id) = (self.broker.clone(), self.id.clone());
        let exit = inst.stop(&shutdown_line(), SHUTDOWN_DEADLINE, |line| broker.route_line(&id, &line)).await;
        self.broker.log(&self.id, &format!("stopped: {exit}"));
    }
    async fn on_exit(&mut self, exit: Exit) {
        self.broker.log(&self.id, &format!("instance ended unexpectedly: {exit}"));
        if let Some(p) = &mut self.probation
            && p.since.elapsed() < CRASH_WINDOW
        {
            p.crashes += 1;
            if p.crashes >= CRASH_LIMIT {
                let (from, to, requester) = (self.version, p.previous, p.requester.clone());
                self.broker.log(&self.id, &format!("version {from} crashed {CRASH_LIMIT} times after the upgrade; rolling back to {to}"));
                let body = match self.rollback(to).await {
                    Ok(_) => json!({"type": "rolled_back", "actor": self.id, "from": from, "to": to,
                                    "reason": "crash loop after upgrade", "last_exit": exit.to_string()}),
                    Err(e) => json!({"type": "error", "actor": self.id, "reason": format!("automatic rollback failed: {e:#}")}),
                };
                self.broker.send("broker", Some(&requester), None, None, body);
                return;
            }
        }
        // Restart after 0.5 s, doubling up to 30 s; a minute of uptime resets it.
        if self.started_at.elapsed() > Duration::from_secs(60) {
            self.restarts = 0;
        }
        let delay = Duration::from_millis(500 << self.restarts.min(6)).min(Duration::from_secs(30));
        self.restarts += 1;
        self.restart_at = Some(Instant::now() + delay);
    }
    /// Make `version` current. It is compiled first (unless `component` is
    /// given): if that fails, nothing changes. `data/` and `public/` stay as
    /// they are.
    async fn install(&mut self, version: u64, component: Option<Component>) -> Result<()> {
        let component = match component {
            Some(c) => c,
            None => self.broker.load_version(&self.id, version)?,
        };
        self.stop().await;
        self.broker.install(&self.id, version)?;
        self.version = version;
        self.component = Some(component);
        self.running = true;
        self.restarts = 0;
        self.restart_at = None;
        Ok(())
    }
    async fn upgrade(&mut self, version: u64, component: Component, requester: String) -> Result<Value> {
        let previous = self.version;
        self.install(version, Some(component)).await?;
        self.probation = Some(Probation { previous, since: Instant::now(), crashes: 0, requester });
        if let Err(e) = self.start().await {
            self.rollback(previous).await?;
            bail!("version {version} did not start ({e:#}); rolled back to {previous}");
        }
        Ok(json!({"type": "upgraded", "actor": self.id, "version": version, "previous": previous}))
    }
    async fn rollback(&mut self, version: u64) -> Result<Value> {
        let from = self.version;
        self.install(version, None).await?;
        self.probation = None;
        self.start().await?;
        Ok(json!({"type": "rolled_back", "actor": self.id, "from": from, "to": version}))
    }
    /// Handle a control request. Returns `true` when the supervisor ends.
    async fn handle(&mut self, ctl: Control) -> bool {
        match ctl {
            Control::Upgrade { version, component, requester, reply } => {
                let _ = reply.send(self.upgrade(version, component, requester).await);
            }
            Control::Rollback { version, reply } => {
                let _ = reply.send(self.rollback(version).await);
            }
            Control::Stop { reply } => {
                self.running = false;
                self.stop().await;
                let r = self.broker.set_running(&self.id, false);
                let _ = reply.send(r.map(|_| json!({"type": "stopped", "actor": self.id})));
            }
            Control::Start { reply } => {
                self.running = true;
                self.restart_at = None;
                let r = self.broker.set_running(&self.id, true);
                let _ = reply.send(r.map(|_| json!({"type": "started", "actor": self.id})));
            }
            Control::Shutdown { reply } => {
                self.stop().await;
                let _ = reply.send(Ok(json!({"type": "shut_down"})));
                return true;
            }
        }
        false
    }
 }
@@ -0,0 +1,716 @@
 //! Actor-served files: `/actor/<id>/fs/...` (see PROTOCOL.md, "Actor-served
 //! files").
 //!
 //! This module wraps the `wasi:filesystem` implementation of `wasmtime-wasi`.
 //! A path under `/actor/<id>/fs/` does not reach the disk: the host asks the
 //! actor `<id>` with a message from `fs` and waits up to `ASK_TIMEOUT` for
 //! the reply. Every other path goes to `wasmtime-wasi` unchanged.
 //!
 //! - `fs_read {path}` -> `fs_file {text | base64}`, `fs_dir {entries: [{name, type}]}`
 //! - `fs_write {path, text | base64}`, `fs_mkdir {path}`, `fs_remove {path}`,
 //!   `fs_rename {path, to}` -> `fs_done`
 //! - any of them -> `fs_error {errno}` (a `wasi:filesystem` error-code name)
 //!
 //! A file is read once when it is opened. After a change, it is written back
 //! in one `fs_write` when it is synced or closed.
 use std::collections::HashSet;
 use std::hash::{Hash, Hasher};
 use std::sync::atomic::{AtomicBool, Ordering};
 use std::sync::{Arc, Mutex, Weak};
 use bytes::Bytes;
 use serde_json::{Value, json};
 use wasmtime::component::{HasData, Resource};
 use wasmtime_wasi::filesystem::WasiFilesystemCtxView;
 use wasmtime_wasi::p2::bindings::filesystem::types::{
    self, DescriptorFlags, DescriptorType, DirectoryEntry, ErrorCode, HostDescriptor, HostDirectoryEntryStream, OpenFlags,
 };
 use wasmtime_wasi::p2::bindings::filesystem::preopens;
 use wasmtime_wasi::p2::pipe::MemoryInputPipe;
 use wasmtime_wasi::p2::{DynInputStream, DynOutputStream, FsError, FsResult, OutputStream, Pollable, StreamResult};
 use crate::broker::Broker;
 /// The `from` of the host's requests. Replies to it go back to the waiting call.
 pub const ID: &str = "fs";
 pub const ASK_TIMEOUT: std::time::Duration = std::time::Duration::from_secs(10);
 /// Per-instance state.
 pub struct VfsState {
    broker: Weak<Broker>,
    /// The actor of this instance, for notes in its `stderr.log`.
    me: String,
    /// Descriptors of the `/actor` preopen.
    roots: HashSet<u32>,
 }
 impl VfsState {
    pub fn new(broker: Weak<Broker>, me: String) -> Self {
        Self { broker, me, roots: HashSet::new() }
    }
 }
 /// [`HasData`] for the linker: the filesystem functions get a [`VfsView`].
 pub struct Vfs;
 impl HasData for Vfs {
    type Data<'a> = VfsView<'a>;
 }
 pub struct VfsView<'a> {
    pub inner: WasiFilesystemCtxView<'a>,
    pub state: &'a mut VfsState,
 }
 /// A descriptor of an actor-served file or folder (in the resource table in
 /// place of a `wasmtime-wasi` descriptor).
 #[derive(Clone)]
 enum Virt {
    Dir { actor: String, path: String },
    File(VFile),
 }
 #[derive(Clone)]
 struct VFile {
    actor: String,
    path: String,
    data: Arc<Mutex<Vec<u8>>>,
    dirty: Arc<AtomicBool>,
    write: bool,
 }
 /// A directory-entry-stream of an actor-served folder.
 struct VDir(std::vec::IntoIter<DirectoryEntry>);
 enum Node {
    File(Vec<u8>),
    Dir(Vec<DirectoryEntry>),
 }
 /// Sends the requests. Owned, so that no borrow of the view lives across an await.
 struct Asker {
    broker: Option<Arc<Broker>>,
    me: String,
 }
 impl Asker {
    async fn ask(&self, actor: &str, body: Value) -> Result<Value, ErrorCode> {
        let broker = self.broker.as_ref().ok_or(ErrorCode::Io)?;
        let what = format!("{} {} to {actor}", body["type"].as_str().unwrap_or(""), body["path"].as_str().unwrap_or(""));
        match broker.ask(actor, body).await {
            None => {
                broker.log(&self.me, &format!("{what}: no reply within {} s", ASK_TIMEOUT.as_secs()));
                Err(ErrorCode::Io)
            }
            Some(reply) => match reply["type"].as_str() {
                Some("fs_error") => Err(errno(&reply["errno"])),
                Some("undeliverable") => Err(ErrorCode::NoEntry),
                _ => Ok(reply),
            },
        }
    }
    async fn read(&self, actor: &str, path: &str) -> Result<Node, ErrorCode> {
        let reply = self.ask(actor, json!({"type": "fs_read", "path": path})).await?;
        match reply["type"].as_str() {
            Some("fs_file") => content(&reply).map(Node::File),
            Some("fs_dir") => Ok(Node::Dir(
                reply["entries"]
                    .as_array()
                    .into_iter()
                    .flatten()
                    .filter_map(|e| {
                        let type_ = if e["type"] == "dir" { DescriptorType::Directory } else { DescriptorType::RegularFile };
                        Some(DirectoryEntry { type_, name: e["name"].as_str()?.to_string() })
                    })
                    .collect(),
            )),
            _ => {
                if let Some(b) = &self.broker {
                    b.log(&self.me, &format!("fs_read {path} to {actor}: unexpected reply {reply}"));
                }
                Err(ErrorCode::Io)
            }
        }
    }
    async fn change(&self, actor: &str, body: Value) -> FsResult<()> {
        self.ask(actor, body).await.map(|_| ()).map_err(FsError::from)
    }
    async fn flush(&self, f: &VFile) -> FsResult<()> {
        if f.dirty.swap(false, Ordering::SeqCst)
            && let Err(e) = self.ask(&f.actor, write_body(f)).await
        {
            f.dirty.store(true, Ordering::SeqCst);
            return Err(e.into());
        }
        Ok(())
    }
 }
 fn errno(v: &Value) -> ErrorCode {
    match v.as_str().unwrap_or("") {
        "no-entry" => ErrorCode::NoEntry,
        "exist" => ErrorCode::Exist,
        "not-directory" => ErrorCode::NotDirectory,
        "is-directory" => ErrorCode::IsDirectory,
        "not-empty" => ErrorCode::NotEmpty,
        "access" => ErrorCode::Access,
        "not-permitted" => ErrorCode::NotPermitted,
        "invalid" => ErrorCode::Invalid,
        "unsupported" => ErrorCode::Unsupported,
        "busy" => ErrorCode::Busy,
        _ => ErrorCode::Io,
    }
 }
 fn content(v: &Value) -> Result<Vec<u8>, ErrorCode> {
    if let Some(text) = v["text"].as_str() {
        return Ok(text.as_bytes().to_vec());
    }
    match v["base64"].as_str() {
        Some(b) => base64_decode(b).ok_or(ErrorCode::IllegalByteSequence),
        None => Ok(Vec::new()),
    }
 }
 fn write_body(f: &VFile) -> Value {
    let data = f.data.lock().unwrap().clone();
    match String::from_utf8(data) {
        Ok(text) => json!({"type": "fs_write", "path": f.path, "text": text}),
        Err(e) => json!({"type": "fs_write", "path": f.path, "base64": base64_encode(e.as_bytes())}),
    }
 }
 /// `rel` resolved against the folder `base`, as an absolute path.
 fn join(base: &str, rel: &str) -> String {
    let mut parts: Vec<&str> = base.split('/').filter(|p| !p.is_empty()).collect();
    for p in rel.split('/') {
        match p {
            "" | "." => {}
            ".." => {
                parts.pop();
            }
            p => parts.push(p),
        }
    }
    format!("/{}", parts.join("/"))
 }
 fn stat(type_: DescriptorType, size: u64) -> types::DescriptorStat {
    types::DescriptorStat {
        type_,
        link_count: 1,
        size,
        data_access_timestamp: None,
        data_modification_timestamp: None,
        status_change_timestamp: None,
    }
 }
 fn node_stat(node: &Node) -> types::DescriptorStat {
    match node {
        Node::File(data) => stat(DescriptorType::RegularFile, data.len() as u64),
        Node::Dir(_) => stat(DescriptorType::Directory, 0),
    }
 }
 fn hash(actor: &str, path: &str) -> types::MetadataHashValue {
    let mut h = std::collections::hash_map::DefaultHasher::new();
    (actor, path).hash(&mut h);
    types::MetadataHashValue { lower: h.finish(), upper: 0 }
 }
 fn write_at(data: &mut Vec<u8>, at: usize, bytes: &[u8]) {
    if data.len() < at + bytes.len() {
        data.resize(at + bytes.len(), 0);
    }
    data[at..at + bytes.len()].copy_from_slice(bytes);
 }
 /// An output stream into an actor-served file (`pos: None` appends).
 struct VWriter {
    file: VFile,
    pos: Option<usize>,
 }
 #[wasmtime_wasi::async_trait]
 impl Pollable for VWriter {
    async fn ready(&mut self) {}
 }
 #[wasmtime_wasi::async_trait]
 impl OutputStream for VWriter {
    fn write(&mut self, bytes: Bytes) -> StreamResult<()> {
        let mut data = self.file.data.lock().unwrap();
        let at = self.pos.unwrap_or(data.len());
        write_at(&mut data, at, &bytes);
        if let Some(p) = &mut self.pos {
            *p += bytes.len();
        }
        self.file.dirty.store(true, Ordering::SeqCst);
        Ok(())
    }
    fn flush(&mut self) -> StreamResult<()> {
        Ok(())
    }
    fn check_write(&mut self) -> StreamResult<usize> {
        Ok(64 * 1024)
    }
 }
 impl VfsView<'_> {
    fn asker(&self) -> Asker {
        Asker { broker: self.state.broker.upgrade(), me: self.state.me.clone() }
    }
    fn virt(&mut self, fd: &Resource<types::Descriptor>) -> Option<Virt> {
        self.inner.table.get_any_mut(fd.rep()).ok()?.downcast_ref::<Virt>().cloned()
    }
    fn file(&mut self, fd: &Resource<types::Descriptor>) -> Option<FsResult<VFile>> {
        match self.virt(fd)? {
            Virt::File(f) => Some(Ok(f)),
            Virt::Dir { .. } => Some(Err(ErrorCode::IsDirectory.into())),
        }
    }
    /// The actor and its path, if `path` relative to `fd` is actor-served.
    fn target(&mut self, fd: &Resource<types::Descriptor>, path: &str) -> Option<(String, String)> {
        match self.virt(fd) {
            Some(Virt::Dir { actor, path: base }) => Some((actor, join(&base, path))),
            Some(Virt::File(f)) => Some((f.actor, join(&f.path, path))),
            None if self.state.roots.contains(&fd.rep()) => {
                let full = join("/", path);
                let mut parts = full.splitn(4, '/').skip(1);
                let (actor, fs, rest) = (parts.next()?, parts.next()?, parts.next().unwrap_or(""));
                (fs == "fs" && !actor.is_empty()).then(|| (actor.to_string(), format!("/{rest}")))
            }
            None => None,
        }
    }
    fn push(&mut self, v: Virt) -> FsResult<Resource<types::Descriptor>> {
        let r = self.inner.table.push(v)?;
        Ok(Resource::new_own(r.rep()))
    }
    async fn open(&mut self, actor: String, path: String, oflags: OpenFlags, flags: DescriptorFlags) -> FsResult<Resource<types::Descriptor>> {
        let write = flags.contains(DescriptorFlags::WRITE);
        let create = oflags.contains(OpenFlags::CREATE);
        let exclusive = create && oflags.contains(OpenFlags::EXCLUSIVE);
        let virt = match self.asker().read(&actor, &path).await {
            Ok(_) if exclusive => return Err(ErrorCode::Exist.into()),
            Ok(Node::Dir(_)) if write => return Err(ErrorCode::IsDirectory.into()),
            Ok(Node::Dir(_)) => Virt::Dir { actor, path },
            Ok(Node::File(_)) if oflags.contains(OpenFlags::DIRECTORY) => return Err(ErrorCode::NotDirectory.into()),
            Ok(Node::File(data)) => {
                let truncate = oflags.contains(OpenFlags::TRUNCATE);
                let data = if truncate { Vec::new() } else { data };
                Virt::File(VFile { actor, path, data: Arc::new(Mutex::new(data)), dirty: Arc::new(AtomicBool::new(truncate)), write })
            }
            Err(ErrorCode::NoEntry) if create && !oflags.contains(OpenFlags::DIRECTORY) => Virt::File(VFile {
                actor,
                path,
                data: Arc::default(),
                dirty: Arc::new(AtomicBool::new(true)),
                write,
            }),
            Err(e) => return Err(e.into()),
        };
        self.push(virt)
    }
    /// Send the changed file without waiting (the descriptor is gone). The
    /// request leaves now, so later requests of this instance come after it.
    fn write_back_later(&self, f: &VFile) {
        let Some(broker) = self.state.broker.upgrade() else { return };
        let reply = broker.ask(&f.actor, write_body(f));
        let (me, what) = (self.state.me.clone(), format!("fs_write {} to {}", f.path, f.actor));
        tokio::spawn(async move {
            match reply.await {
                Some(r) if r["type"] != "fs_error" && r["type"] != "undeliverable" => {}
                r => broker.log(&me, &format!("{what} failed: {}", r.map_or("no reply".to_string(), |r| r.to_string()))),
            }
        });
    }
 }
 impl preopens::Host for VfsView<'_> {
    fn get_directories(&mut self) -> wasmtime::Result<Vec<(Resource<types::Descriptor>, String)>> {
        let dirs = preopens::Host::get_directories(&mut self.inner)?;
        for (fd, name) in &dirs {
            if name == "/actor" {
                self.state.roots.insert(fd.rep());
            }
        }
        Ok(dirs)
    }
 }
 impl types::Host for VfsView<'_> {
    fn convert_error_code(&mut self, err: FsError) -> wasmtime::Result<ErrorCode> {
        types::Host::convert_error_code(&mut self.inner, err)
    }
    fn filesystem_error_code(&mut self, err: Resource<wasmtime::Error>) -> wasmtime::Result<Option<ErrorCode>> {
        types::Host::filesystem_error_code(&mut self.inner, err)
    }
 }
 impl HostDescriptor for VfsView<'_> {
    async fn advise(&mut self, fd: Resource<types::Descriptor>, offset: types::Filesize, len: types::Filesize, advice: types::Advice) -> FsResult<()> {
        if self.virt(&fd).is_some() {
            return Ok(());
        }
        HostDescriptor::advise(&mut self.inner, fd, offset, len, advice).await
    }
    async fn sync_data(&mut self, fd: Resource<types::Descriptor>) -> FsResult<()> {
        match self.virt(&fd) {
            Some(Virt::File(f)) => self.asker().flush(&f).await,
            Some(Virt::Dir { .. }) => Ok(()),
            None => HostDescriptor::sync_data(&mut self.inner, fd).await,
        }
    }
    async fn get_flags(&mut self, fd: Resource<types::Descriptor>) -> FsResult<DescriptorFlags> {
        match self.virt(&fd) {
            Some(Virt::File(f)) if f.write => Ok(DescriptorFlags::READ | DescriptorFlags::WRITE),
            Some(Virt::File(_)) => Ok(DescriptorFlags::READ),
            Some(Virt::Dir { .. }) => Ok(DescriptorFlags::READ | DescriptorFlags::MUTATE_DIRECTORY),
            None => HostDescriptor::get_flags(&mut self.inner, fd).await,
        }
    }
    async fn get_type(&mut self, fd: Resource<types::Descriptor>) -> FsResult<DescriptorType> {
        match self.virt(&fd) {
            Some(Virt::File(_)) => Ok(DescriptorType::RegularFile),
            Some(Virt::Dir { .. }) => Ok(DescriptorType::Directory),
            None => HostDescriptor::get_type(&mut self.inner, fd).await,
        }
    }
    async fn set_size(&mut self, fd: Resource<types::Descriptor>, size: types::Filesize) -> FsResult<()> {
        match self.file(&fd) {
            Some(f) => {
                let f = f?;
                if !f.write {
                    return Err(ErrorCode::NotPermitted.into());
                }
                f.data.lock().unwrap().resize(size as usize, 0);
                f.dirty.store(true, Ordering::SeqCst);
                Ok(())
            }
            None => HostDescriptor::set_size(&mut self.inner, fd, size).await,
        }
    }
    async fn set_times(&mut self, fd: Resource<types::Descriptor>, atim: types::NewTimestamp, mtim: types::NewTimestamp) -> FsResult<()> {
        if self.virt(&fd).is_some() {
            return Ok(());
        }
        HostDescriptor::set_times(&mut self.inner, fd, atim, mtim).await
    }
    async fn read(&mut self, fd: Resource<types::Descriptor>, len: types::Filesize, offset: types::Filesize) -> FsResult<(Vec<u8>, bool)> {
        match self.file(&fd) {
            Some(f) => {
                let f = f?;
                let data = f.data.lock().unwrap();
                let start = usize::try_from(offset).unwrap_or(usize::MAX).min(data.len());
                let end = start.saturating_add(usize::try_from(len).unwrap_or(usize::MAX)).min(data.len());
                Ok((data[start..end].to_vec(), start == end))
            }
            None => HostDescriptor::read(&mut self.inner, fd, len, offset).await,
        }
    }
    async fn write(&mut self, fd: Resource<types::Descriptor>, buf: Vec<u8>, offset: types::Filesize) -> FsResult<types::Filesize> {
        match self.file(&fd) {
            Some(f) => {
                let f = f?;
                if !f.write {
                    return Err(ErrorCode::NotPermitted.into());
                }
                write_at(&mut f.data.lock().unwrap(), offset as usize, &buf);
                f.dirty.store(true, Ordering::SeqCst);
                Ok(buf.len() as u64)
            }
            None => HostDescriptor::write(&mut self.inner, fd, buf, offset).await,
        }
    }
    async fn read_directory(&mut self, fd: Resource<types::Descriptor>) -> FsResult<Resource<types::DirectoryEntryStream>> {
        match self.virt(&fd) {
            Some(Virt::Dir { actor, path }) => match self.asker().read(&actor, &path).await? {
                Node::Dir(entries) => {
                    let r = self.inner.table.push(VDir(entries.into_iter()))?;
                    Ok(Resource::new_own(r.rep()))
                }
                Node::File(_) => Err(ErrorCode::NotDirectory.into()),
            },
            Some(Virt::File(_)) => Err(ErrorCode::NotDirectory.into()),
            None => HostDescriptor::read_directory(&mut self.inner, fd).await,
        }
    }
    async fn sync(&mut self, fd: Resource<types::Descriptor>) -> FsResult<()> {
        match self.virt(&fd) {
            Some(Virt::File(f)) => self.asker().flush(&f).await,
            Some(Virt::Dir { .. }) => Ok(()),
            None => HostDescriptor::sync(&mut self.inner, fd).await,
        }
    }
    async fn create_directory_at(&mut self, fd: Resource<types::Descriptor>, path: String) -> FsResult<()> {
        match self.target(&fd, &path) {
            Some((actor, path)) => self.asker().change(&actor, json!({"type": "fs_mkdir", "path": path})).await,
            None => HostDescriptor::create_directory_at(&mut self.inner, fd, path).await,
        }
    }
    async fn stat(&mut self, fd: Resource<types::Descriptor>) -> FsResult<types::DescriptorStat> {
        match self.virt(&fd) {
            Some(Virt::File(f)) => Ok(stat(DescriptorType::RegularFile, f.data.lock().unwrap().len() as u64)),
            Some(Virt::Dir { .. }) => Ok(stat(DescriptorType::Directory, 0)),
            None => HostDescriptor::stat(&mut self.inner, fd).await,
        }
    }
    async fn stat_at(&mut self, fd: Resource<types::Descriptor>, path_flags: types::PathFlags, path: String) -> FsResult<types::DescriptorStat> {
        match self.target(&fd, &path) {
            Some((actor, path)) => Ok(node_stat(&self.asker().read(&actor, &path).await?)),
            None => HostDescriptor::stat_at(&mut self.inner, fd, path_flags, path).await,
        }
    }
    async fn set_times_at(
        &mut self,
        fd: Resource<types::Descriptor>,
        path_flags: types::PathFlags,
        path: String,
        atim: types::NewTimestamp,
        mtim: types::NewTimestamp,
    ) -> FsResult<()> {
        if self.target(&fd, &path).is_some() {
            return Ok(());
        }
        HostDescriptor::set_times_at(&mut self.inner, fd, path_flags, path, atim, mtim).await
    }
    async fn link_at(
        &mut self,
        fd: Resource<types::Descriptor>,
        old_path_flags: types::PathFlags,
        old_path: String,
        new_descriptor: Resource<types::Descriptor>,
        new_path: String,
    ) -> FsResult<()> {
        if self.target(&fd, &old_path).is_some() || self.target(&new_descriptor, &new_path).is_some() {
            return Err(ErrorCode::Unsupported.into());
        }
        HostDescriptor::link_at(&mut self.inner, fd, old_path_flags, old_path, new_descriptor, new_path).await
    }
    async fn open_at(
        &mut self,
        fd: Resource<types::Descriptor>,
        path_flags: types::PathFlags,
        path: String,
        oflags: OpenFlags,
        flags: DescriptorFlags,
    ) -> FsResult<Resource<types::Descriptor>> {
        match self.target(&fd, &path) {
            Some((actor, path)) => self.open(actor, path, oflags, flags).await,
            None => HostDescriptor::open_at(&mut self.inner, fd, path_flags, path, oflags, flags).await,
        }
    }
    fn drop(&mut self, fd: Resource<types::Descriptor>) -> wasmtime::Result<()> {
        if self.virt(&fd).is_some() {
            if let Virt::File(f) = self.inner.table.delete(Resource::<Virt>::new_own(fd.rep()))?
                && f.dirty.load(Ordering::SeqCst)
            {
                self.write_back_later(&f);
            }
            return Ok(());
        }
        self.state.roots.remove(&fd.rep());
        HostDescriptor::drop(&mut self.inner, fd)
    }
    async fn readlink_at(&mut self, fd: Resource<types::Descriptor>, path: String) -> FsResult<String> {
        if self.target(&fd, &path).is_some() {
            return Err(ErrorCode::Invalid.into());
        }
        HostDescriptor::readlink_at(&mut self.inner, fd, path).await
    }
    async fn remove_directory_at(&mut self, fd: Resource<types::Descriptor>, path: String) -> FsResult<()> {
        match self.target(&fd, &path) {
            Some((actor, path)) => self.asker().change(&actor, json!({"type": "fs_remove", "path": path})).await,
            None => HostDescriptor::remove_directory_at(&mut self.inner, fd, path).await,
        }
    }
    async fn rename_at(&mut self, fd: Resource<types::Descriptor>, old_path: String, new_fd: Resource<types::Descriptor>, new_path: String) -> FsResult<()> {
        match (self.target(&fd, &old_path), self.target(&new_fd, &new_path)) {
            (None, None) => HostDescriptor::rename_at(&mut self.inner, fd, old_path, new_fd, new_path).await,
            (Some((a, from)), Some((b, to))) if a == b => {
                self.asker().change(&a, json!({"type": "fs_rename", "path": from, "to": to})).await
            }
            _ => Err(ErrorCode::Unsupported.into()),
        }
    }
    async fn symlink_at(&mut self, fd: Resource<types::Descriptor>, src_path: String, dest_path: String) -> FsResult<()> {
        if self.target(&fd, &dest_path).is_some() {
            return Err(ErrorCode::Unsupported.into());
        }
        HostDescriptor::symlink_at(&mut self.inner, fd, src_path, dest_path).await
    }
    async fn unlink_file_at(&mut self, fd: Resource<types::Descriptor>, path: String) -> FsResult<()> {
        match self.target(&fd, &path) {
            Some((actor, path)) => self.asker().change(&actor, json!({"type": "fs_remove", "path": path})).await,
            None => HostDescriptor::unlink_file_at(&mut self.inner, fd, path).await,
        }
    }
    fn read_via_stream(&mut self, fd: Resource<types::Descriptor>, offset: types::Filesize) -> FsResult<Resource<DynInputStream>> {
        match self.file(&fd) {
            Some(f) => {
                let f = f?;
                let data = f.data.lock().unwrap();
                let start = usize::try_from(offset).unwrap_or(usize::MAX).min(data.len());
                let stream: DynInputStream = Box::new(MemoryInputPipe::new(data[start..].to_vec()));
                std::mem::drop(data);
                Ok(self.inner.table.push(stream)?)
            }
            None => HostDescriptor::read_via_stream(&mut self.inner, fd, offset),
        }
    }
    fn write_via_stream(&mut self, fd: Resource<types::Descriptor>, offset: types::Filesize) -> FsResult<Resource<DynOutputStream>> {
        match self.file(&fd) {
            Some(f) => {
                let f = f?;
                if !f.write {
                    return Err(ErrorCode::NotPermitted.into());
                }
                let stream: DynOutputStream = Box::new(VWriter { file: f, pos: Some(offset as usize) });
                Ok(self.inner.table.push(stream)?)
            }
            None => HostDescriptor::write_via_stream(&mut self.inner, fd, offset),
        }
    }
    fn append_via_stream(&mut self, fd: Resource<types::Descriptor>) -> FsResult<Resource<DynOutputStream>> {
        match self.file(&fd) {
            Some(f) => {
                let f = f?;
                if !f.write {
                    return Err(ErrorCode::NotPermitted.into());
                }
                let stream: DynOutputStream = Box::new(VWriter { file: f, pos: None });
                Ok(self.inner.table.push(stream)?)
            }
            None => HostDescriptor::append_via_stream(&mut self.inner, fd),
        }
    }
    async fn is_same_object(&mut self, a: Resource<types::Descriptor>, b: Resource<types::Descriptor>) -> wasmtime::Result<bool> {
        let key = |v: Virt| match v {
            Virt::Dir { actor, path } => (actor, path),
            Virt::File(f) => (f.actor, f.path),
        };
        match (self.virt(&a), self.virt(&b)) {
            (None, None) => HostDescriptor::is_same_object(&mut self.inner, a, b).await,
            (Some(x), Some(y)) => Ok(key(x) == key(y)),
            _ => Ok(false),
        }
    }
    async fn metadata_hash(&mut self, fd: Resource<types::Descriptor>) -> FsResult<types::MetadataHashValue> {
        match self.virt(&fd) {
            Some(Virt::Dir { actor, path }) => Ok(hash(&actor, &path)),
            Some(Virt::File(f)) => Ok(hash(&f.actor, &f.path)),
            None => HostDescriptor::metadata_hash(&mut self.inner, fd).await,
        }
    }
    async fn metadata_hash_at(&mut self, fd: Resource<types::Descriptor>, path_flags: types::PathFlags, path: String) -> FsResult<types::MetadataHashValue> {
        match self.target(&fd, &path) {
            Some((actor, path)) => Ok(hash(&actor, &path)),
            None => HostDescriptor::metadata_hash_at(&mut self.inner, fd, path_flags, path).await,
        }
    }
 }
 impl HostDirectoryEntryStream for VfsView<'_> {
    async fn read_directory_entry(&mut self, stream: Resource<types::DirectoryEntryStream>) -> FsResult<Option<DirectoryEntry>> {
        if let Some(dir) = self.inner.table.get_any_mut(stream.rep()).ok().and_then(|a| a.downcast_mut::<VDir>()) {
            return Ok(dir.0.next());
        }
        HostDirectoryEntryStream::read_directory_entry(&mut self.inner, stream).await
    }
    fn drop(&mut self, stream: Resource<types::DirectoryEntryStream>) -> wasmtime::Result<()> {
        let ours = self.inner.table.get_any_mut(stream.rep()).ok().is_some_and(|a| a.is::<VDir>());
        if ours {
            self.inner.table.delete(Resource::<VDir>::new_own(stream.rep()))?;
            return Ok(());
        }
        HostDirectoryEntryStream::drop(&mut self.inner, stream)
    }
 }
 const B64: &[u8; 64] = b"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
 fn base64_encode(bytes: &[u8]) -> String {
    let mut out = String::with_capacity(bytes.len().div_ceil(3) * 4);
    for chunk in bytes.chunks(3) {
        let n = chunk.iter().enumerate().fold(0u32, |n, (i, b)| n | (*b as u32) << (16 - 8 * i));
        for i in 0..4 {
            out.push(if i <= chunk.len() { B64[(n >> (18 - 6 * i) & 63) as usize] as char } else { '=' });
        }
    }
    out
 }
 fn base64_decode(text: &str) -> Option<Vec<u8>> {
    let (mut out, mut n, mut bits) = (Vec::new(), 0u32, 0);
    for c in text.bytes().filter(|c| !c.is_ascii_whitespace() && *c != b'=') {
        n = (n << 6 | B64.iter().position(|b| *b == c)? as u32) & 0xFF_FFFF;
        bits += 6;
        if bits >= 8 {
            bits -= 8;
            out.push((n >> bits) as u8);
        }
    }
    Some(out)
 }
 #[cfg(test)]
 mod tests {
    use super::*;
    #[test]
    fn base64_round_trip() {
        for s in ["", "a", "ab", "abc", "abcd", "\u{0}\u{ff}binary"] {
            let enc = base64_encode(s.as_bytes());
            assert_eq!(base64_decode(&enc).unwrap(), s.as_bytes());
        }
        assert_eq!(base64_encode(b"hello"), "aGVsbG8=");
    }
    #[test]
    fn join_resolves_dots() {
        assert_eq!(join("/a/b", "../c/./d"), "/a/c/d");
        assert_eq!(join("/", "x/fs"), "/x/fs");
        assert_eq!(join("/", ".."), "/");
    }
 }
@@ -1,47 +1,58 @@
-//! On-disk layout of a Sausage workspace ("world").
+//! On-disk layout of a Sausage world. The folder is the source of truth:
 //! `sausage run` boots every actor that it finds in `actor/`.
 //!
 //! ```text
 //! <world>/
-//!   sausage.json                 registry: actors, versions, subscriptions
+//!   actor/<id>/
-//!   actor/<id>/public/           written by the actor, read-only for others
+//!     actor.wasm        the current version
-//!   actor/<id>/source/           source of the running version (broker)
+//!     actor.json        version, running, subscriptions, tapped (broker)
-//!   actor/<id>/status.json       state of the actor (broker)
+//!     source/           source of the current version
-//!   actor/<id>/stderr.log        stderr of the actor (broker)
+//!     public/           written by the actor, read-only for others
-//!   private/<id>/data/           private state of the actor
+//!     data/             state, writable only by the actor
-//!   broker/versions/<id>/<n>/    actor.wasm, source/, meta.json, snapshot/
+//!     stderr.log        stderr of the actor and notes of the broker
-//!   archive/                     removed actors
+//!     versions/<n>/     every version that was installed: actor.wasm, source/, meta.json
 //! ```
-use std::collections::{BTreeMap, BTreeSet};
+use std::collections::BTreeSet;
-use std::path::{Path, PathBuf};
+use std::path::{Component, Path, PathBuf};
 use anyhow::{Context, Result, bail};
 use serde::{Deserialize, Serialize};
-use crate::fs::TMP_PREFIX;
+/// Name prefix of the host's temporary files and folders. Copies skip them.
 pub const TMP_PREFIX: &str = ".sausage-tmp-";
-/// IDs of the actors that the host implements natively.
+/// IDs of the actors that the host implements natively. `fs` sends the
-pub const NATIVE: &[&str] = &["broker", "console", "cargo"];
+/// requests for actor-served files (`vfs.rs`).
 pub const NATIVE: &[&str] = &["broker", "console", "cargo", "fs"];
 #[derive(Clone)]
 pub struct World {
    pub root: PathBuf,
 }
-#[derive(Default, Serialize, Deserialize, Clone)]
+/// `actor/<id>/actor.json`.
-pub struct Registry {
+#[derive(Serialize, Deserialize, Clone, Debug, Default)]
-    pub actors: BTreeMap<String, ActorRecord>,
+pub struct ActorMeta {
-    /// Publisher ID → subscriber IDs.
+    /// The installed version. `None` for native actors and for a new
-    pub subscriptions: BTreeMap<String, BTreeSet<String>>,
+    /// `actor.wasm` that the broker has not installed yet.
-}
+    #[serde(default)]
-
+    pub version: Option<u64>,
-#[derive(Serialize, Deserialize, Clone, Debug)]
+    #[serde(default = "yes")]
 pub struct ActorRecord {
    pub version: u64,
    pub next_version: u64,
    pub running: bool,
    /// The actors whose published messages this actor receives.
    #[serde(default)]
    pub subscriptions: BTreeSet<String>,
    /// Whether this actor gets a copy of every routed message (`tap`).
    #[serde(default)]
    pub tapped: bool,
 }
 fn yes() -> bool {
    true
 }
 /// `versions/<n>/meta.json`.
 #[derive(Serialize, Deserialize, Clone, Debug, Default)]
 pub struct VersionMeta {
    pub version: u64,
@@ -51,7 +62,7 @@ pub struct VersionMeta {
    pub source: Option<String>,
    /// The actor that built the `.wasm` file.
    pub built_by: Option<String>,
-    /// The actor that requested the spawn or upgrade.
+    /// The actor that requested the version ("scan" for a file found on disk).
    pub requested_by: String,
    pub created_at: u64,
 }
@@ -74,15 +85,15 @@ impl World {
        Self { root: root.into() }
    }
    pub fn registry_path(&self) -> PathBuf {
        self.root.join("sausage.json")
    }
    pub fn actor_dir(&self, id: &str) -> PathBuf {
        self.root.join("actor").join(id)
    }
    pub fn actors_root(&self) -> PathBuf {
        self.root.join("actor")
    }
    pub fn actor_dir(&self, id: &str) -> PathBuf {
        self.actors_root().join(id)
    }
    pub fn wasm_path(&self, id: &str) -> PathBuf {
        self.actor_dir(id).join("actor.wasm")
    }
    pub fn public_dir(&self, id: &str) -> PathBuf {
        self.actor_dir(id).join("public")
    }
@@ -90,37 +101,88 @@ impl World {
        self.actor_dir(id).join("source")
    }
    pub fn data_dir(&self, id: &str) -> PathBuf {
-        self.root.join("private").join(id).join("data")
+        self.actor_dir(id).join("data")
    }
    pub fn versions_dir(&self, id: &str) -> PathBuf {
-        self.root.join("broker").join("versions").join(id)
+        self.actor_dir(id).join("versions")
    }
    pub fn version_dir(&self, id: &str, v: u64) -> PathBuf {
        self.versions_dir(id).join(v.to_string())
    }
    /// Private scratch space of the broker (candidate copies, seeds).
    pub fn scratch_dir(&self) -> PathBuf {
-        self.root.join("broker").join("scratch")
+        self.data_dir("broker").join("scratch")
    }
    pub fn exists(&self) -> bool {
-        self.registry_path().is_file()
+        self.actors_root().is_dir()
    }
    /// Create an empty world with the folders of the native actors.
    pub fn create(root: &Path) -> Result<World> {
        let world = World::new(std::path::absolute(root)?);
        if world.exists() {
            bail!("{} is already a Sausage world", root.display());
        }
        for id in NATIVE {
            world.ensure_actor_dirs(id)?;
        }
        Ok(world)
    }
    /// Create the directories of one actor.
    pub fn ensure_actor_dirs(&self, id: &str) -> Result<()> {
        std::fs::create_dir_all(self.public_dir(id))?;
        std::fs::create_dir_all(self.data_dir(id))?;
        Ok(())
    }
-    pub fn load_registry(&self) -> Result<Registry> {
+    /// IDs of every folder in `actor/`, sorted.
-        let text = std::fs::read_to_string(self.registry_path())
+    pub fn actor_ids(&self) -> Result<Vec<String>> {
-            .with_context(|| format!("no Sausage world at {}", self.root.display()))?;
+        let mut ids: Vec<String> = std::fs::read_dir(self.actors_root())?
-        Ok(serde_json::from_str(&text)?)
+            .filter_map(|e| e.ok())
            .filter(|e| e.path().is_dir())
            .filter_map(|e| e.file_name().into_string().ok())
            .filter(|id| valid_id(id))
            .collect();
        ids.sort();
        Ok(ids)
    }
-    pub fn save_registry(&self, reg: &Registry) -> Result<()> {
+    pub fn read_meta(&self, id: &str) -> ActorMeta {
-        write_atomic(&self.registry_path(), serde_json::to_string_pretty(reg)?.as_bytes())
+        std::fs::read_to_string(self.actor_dir(id).join("actor.json"))
            .ok()
            .and_then(|s| serde_json::from_str(&s).ok())
            .unwrap_or(ActorMeta { running: true, ..Default::default() })
    }
    pub fn write_meta(&self, id: &str, meta: &ActorMeta) -> Result<()> {
        write_atomic(&self.actor_dir(id).join("actor.json"), serde_json::to_string_pretty(meta)?.as_bytes())
    }
    /// Make `actor.wasm` and `source/` a copy of `versions/<version>/`,
    /// unless `actor.wasm` already is that version (it came from there).
    pub fn install_files(&self, id: &str, version: u64) -> Result<()> {
        let dir = self.version_dir(id, version);
        self.ensure_actor_dirs(id)?;
        let wasm = std::fs::read(dir.join("actor.wasm"))?;
        if std::fs::read(self.wasm_path(id)).ok().as_ref() == Some(&wasm) {
            return Ok(());
        }
        write_atomic(&self.wasm_path(id), &wasm)?;
        replace_tree(&dir.join("source"), &self.source_dir(id))
    }
    /// Version numbers in `versions/`, ascending.
    pub fn versions(&self, id: &str) -> Vec<u64> {
        let mut v: Vec<u64> = std::fs::read_dir(self.versions_dir(id))
            .map(|rd| rd.filter_map(|e| e.ok()?.file_name().to_str()?.parse().ok()).collect())
            .unwrap_or_default();
        v.sort();
        v
    }
    pub fn next_version(&self, id: &str) -> u64 {
        self.versions(id).last().map_or(1, |v| v + 1)
    }
    /// Map a path in an actor's namespace to a host path.
@@ -129,25 +191,28 @@ impl World {
    /// - `/public/...` and `/data/...` belong to `sender`.
    /// - Native senders (the console) can also give absolute host paths.
    pub fn resolve(&self, sender: &str, path: &str) -> Result<PathBuf> {
-        let clean = |base: PathBuf, rest: &str| -> Result<PathBuf> {
+        let under = |base: PathBuf, rest: &str| -> Result<PathBuf> {
-            let mut out = base.clone();
+            let mut out = base;
            for c in Path::new(rest).components() {
                match c {
-                    std::path::Component::Normal(n) => out.push(n),
+                    Component::Normal(n) => out.push(n),
-                    std::path::Component::CurDir | std::path::Component::RootDir => {}
+                    Component::CurDir | Component::RootDir => {}
                    _ => bail!("path must not contain '..': {path}"),
                }
            }
            Ok(out)
        };
-        if let Some(rest) = path.strip_prefix("/actor/") {
+        let prefixed = |prefix: &str| {
-            return clean(self.actors_root(), rest);
+            path.strip_prefix(prefix).filter(|rest| rest.is_empty() || rest.starts_with('/'))
        };
        if let Some(rest) = prefixed("/actor") {
            return under(self.actors_root(), rest);
        }
-        if let Some(rest) = path.strip_prefix("/public/").or(path.strip_prefix("/public").filter(|r| r.is_empty())) {
+        if let Some(rest) = prefixed("/public") {
-            return clean(self.public_dir(sender), rest);
+            return under(self.public_dir(sender), rest);
        }
-        if let Some(rest) = path.strip_prefix("/data/").or(path.strip_prefix("/data").filter(|r| r.is_empty())) {
+        if let Some(rest) = prefixed("/data") {
-            return clean(self.data_dir(sender), rest);
+            return under(self.data_dir(sender), rest);
        }
        if NATIVE.contains(&sender) && Path::new(path).is_absolute() {
            return Ok(PathBuf::from(path));
@@ -166,33 +231,34 @@ impl World {
 pub fn write_atomic(path: &Path, bytes: &[u8]) -> Result<()> {
    let dir = path.parent().context("path has no parent")?;
    std::fs::create_dir_all(dir)?;
-    let tmp = dir.join(format!(
+    let name = path.file_name().and_then(|n| n.to_str()).unwrap_or("file");
-        "{TMP_PREFIX}host-{}-{}",
+    let tmp = dir.join(format!("{TMP_PREFIX}host-{}-{name}", std::process::id()));
        std::process::id(),
        path.file_name().and_then(|n| n.to_str()).unwrap_or("file")
    ));
    std::fs::write(&tmp, bytes)?;
    std::fs::rename(&tmp, path)?;
    Ok(())
 }
-/// Copy a directory tree. Skips `target/` folders and uncommitted files.
+/// Folders that a copy of a source folder leaves out.
 const BUILD_DIRS: &[&str] = &["target", ".git"];
 /// Copy a directory tree, except uncommitted files.
 pub fn copy_tree(from: &Path, to: &Path) -> Result<()> {
    copy_filtered(from, to, &[])
 }
 fn copy_filtered(from: &Path, to: &Path, skip: &[&str]) -> Result<()> {
    std::fs::create_dir_all(to)?;
    for entry in std::fs::read_dir(from).with_context(|| format!("read {}", from.display()))? {
        let entry = entry?;
        let name = entry.file_name();
-        let name_str = name.to_string_lossy();
+        let name = name.to_string_lossy();
-        if name_str.starts_with(TMP_PREFIX) {
+        if name.starts_with(TMP_PREFIX) {
            continue;
        }
        let dst = to.join(&*name);
        let ty = entry.file_type()?;
-        let dst = to.join(&name);
+        if ty.is_dir() && !skip.contains(&&*name) {
-        if ty.is_dir() {
+            copy_filtered(&entry.path(), &dst, skip)?;
            if name_str == "target" || name_str == ".git" {
                continue;
            }
            copy_tree(&entry.path(), &dst)?;
        } else if ty.is_file() {
            std::fs::copy(entry.path(), &dst)?;
        }
@@ -200,9 +266,18 @@ pub fn copy_tree(from: &Path, to: &Path) -> Result<()> {
    Ok(())
 }
-/// Replace the directory `dst` with a copy of `src`, as close to atomic as a
+/// Replace the directory `dst` with a copy of `src` (an empty folder if `src`
-/// directory can be: copy to a sibling, then swap with two renames.
+/// does not exist): copy to a sibling, then swap with two renames.
 pub fn replace_tree(src: &Path, dst: &Path) -> Result<()> {
    replace_filtered(src, dst, &[])
 }
 /// Like `replace_tree`, for a source folder: leaves out `target/` and `.git/`.
 pub fn replace_source(src: &Path, dst: &Path) -> Result<()> {
    replace_filtered(src, dst, BUILD_DIRS)
 }
 fn replace_filtered(src: &Path, dst: &Path, skip: &[&str]) -> Result<()> {
    let parent = dst.parent().context("path has no parent")?;
    let name = dst.file_name().and_then(|n| n.to_str()).unwrap_or("dir");
    let fresh = parent.join(format!("{TMP_PREFIX}new-{name}"));
@@ -210,7 +285,7 @@ pub fn replace_tree(src: &Path, dst: &Path) -> Result<()> {
    let _ = std::fs::remove_dir_all(&fresh);
    let _ = std::fs::remove_dir_all(&old);
    if src.is_dir() {
-        copy_tree(src, &fresh)?;
+        copy_filtered(src, &fresh, skip)?;
    } else {
        std::fs::create_dir_all(&fresh)?;
    }
@@ -0,0 +1,105 @@
 # This file is automatically @generated by Cargo.
 # It is not intended for manual editing.
 version = 4
 [[package]]
 name = "itoa"
 version = "1.0.18"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "8f42a60cbdf9a97f5d2305f08a87dc4e09308d1276d28c869c684d7777685682"
 [[package]]
 name = "memchr"
 version = "2.8.3"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "cf8baf1c55e62ffcace7a9f06f4bd9cd3f0c4beb022d3b367256b91b87513d98"
 [[package]]
 name = "proc-macro2"
 version = "1.0.107"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "985e7ec9bb745e6ce6535b544d84d6cd6f7ad8bd711c398938ae983b91a766d9"
 dependencies = [
 "unicode-ident",
 ]
 [[package]]
 name = "quote"
 version = "1.0.47"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "1fbf4db142a473a8d80c26bbf18454ed458bf8d26c8219c331daecfdbd079001"
 dependencies = [
 "proc-macro2",
 ]
 [[package]]
 name = "serde"
 version = "1.0.229"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "4148590afebada386688f18773da617792bf2ef03ffc1e4cbd2b1d45b023e0ba"
 dependencies = [
 "serde_core",
 ]
 [[package]]
 name = "serde_core"
 version = "1.0.229"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "67dca2c9c51e58a4791a4b1ed58308b39c64224d349a935ab5039aa360942a48"
 dependencies = [
 "serde_derive",
 ]
 [[package]]
 name = "serde_derive"
 version = "1.0.229"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "e7a5d71263a5a7d47b41f6b3f06ba276f10cc18b0931f1799f710578e2309348"
 dependencies = [
 "proc-macro2",
 "quote",
 "syn",
 ]
 [[package]]
 name = "serde_json"
 version = "1.0.154"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "e7e9cc8b1b85264074fbcc02a88680c4096b1e47df8f739dceb03bf482f04bd6"
 dependencies = [
 "itoa",
 "memchr",
 "serde",
 "serde_core",
 "zmij",
 ]
 [[package]]
 name = "syn"
 version = "3.0.9"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "d78c8dee4c7bf0e14673097256fed6142ce9d3b85a408189d07482442145823b"
 dependencies = [
 "proc-macro2",
 "quote",
 "unicode-ident",
 ]
 [[package]]
 name = "toolbox"
 version = "0.1.0"
 dependencies = [
 "serde_json",
 ]
 [[package]]
 name = "unicode-ident"
 version = "1.0.27"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "a2c754d6c33795a1c324727428e5a7dedb5b06195f9890bdbcba760d3e246563"
 [[package]]
 name = "zmij"
 version = "1.0.23"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "29666d0abbfad1e3dc4dcf6144730dd3a3ab225bbbdac83319345b1b44ccfc1b"
@@ -1,7 +1,9 @@
 [package]
-name = "fstest"
+name = "toolbox"
 version = "0.1.0"
 edition = "2024"
 [dependencies]
 serde_json = "1"
 [workspace]
@@ -0,0 +1,180 @@
 use std::collections::HashMap;
 use std::io::{self, BufRead, Write};
 use std::time::{Duration, SystemTime, UNIX_EPOCH};
 use serde_json::{Value, json};
 fn send(out: &mut impl Write, message: Value) {
    writeln!(out, "{message}").unwrap();
    out.flush().unwrap();
 }
 fn reply(out: &mut impl Write, message: &Value, body: Value) {
    send(
        out,
        json!({"to": message["from"], "reply_to": message["id"], "body": body}),
    );
 }
 /// Connect to `address`, send one line, and return the line that comes back.
 fn tcp_line(address: &str, line: &str) -> io::Result<String> {
    let mut stream = std::net::TcpStream::connect(address)?;
    writeln!(stream, "{line}")?;
    let mut answer = String::new();
    io::BufReader::new(stream).read_line(&mut answer)?;
    Ok(answer.trim_end().to_string())
 }
 fn io_error(error: io::Error) -> Value {
    json!({"type": "error", "error": error.to_string()})
 }
 fn main() {
    let actor = std::env::var("SAUSAGE_ACTOR").unwrap_or_default();
    let version = std::env::var("SAUSAGE_VERSION").unwrap_or_else(|_| "candidate".to_string());
    let candidate = std::env::var_os("SAUSAGE_CANDIDATE").is_some();
    if actor == "crashloop" && version == "2" && !candidate {
        std::fs::write("/data/state", "bad-v2").unwrap();
        panic!("version 2 crashes on startup");
    }
    let mut open = HashMap::<String, std::fs::File>::new();
    // Files that this actor serves at /actor/<id>/fs/ (path -> text).
    let mut served = std::collections::BTreeMap::<String, String>::new();
    let stdin = io::stdin();
    let mut out = io::stdout().lock();
    let mut emit_shutdown = false;
    if actor == "spawn-race" && !candidate {
        let stamp = SystemTime::now()
            .duration_since(UNIX_EPOCH)
            .unwrap()
            .as_nanos();
        std::fs::write(format!("/data/start-{stamp}"), "started").unwrap();
    }
    for line in stdin.lock().lines() {
        let Ok(line) = line else { break };
        let Ok(message) = serde_json::from_str::<Value>(&line) else {
            continue;
        };
        let body = &message["body"];
        let path = body["path"].as_str().unwrap_or_default().to_string();
        let text = body["text"].as_str().unwrap_or_default();
        let response = match body["type"].as_str() {
            Some("shutdown") => {
                if actor == "queue" {
                    let _ = std::fs::write("/data/shutdown", "stopping");
                    std::thread::sleep(Duration::from_millis(800));
                }
                if emit_shutdown {
                    send(
                        &mut out,
                        json!({"to": "console", "reply_to": message["id"], "body": {"type": "shutdown-reply"}}),
                    );
                    send(&mut out, json!({"body": {"type": "shutdown-publish"}}));
                }
                break;
            }
            Some("echo") => json!({"type": "echo", "value": body["value"]}),
            Some("fs_read") => {
                let dir = if path == "/" { "/".to_string() } else { format!("{path}/") };
                let mut names: Vec<String> = served
                    .keys()
                    .filter_map(|k| k.strip_prefix(&dir))
                    .map(|rest| match rest.split_once('/') {
                        Some((first, _)) => format!("{first}/"),
                        None => rest.to_string(),
                    })
                    .collect();
                names.dedup();
                if let Some(text) = served.get(&path) {
                    json!({"type": "fs_file", "text": text})
                } else if path == "/" || !names.is_empty() {
                    let entries: Vec<Value> = names
                        .iter()
                        .map(|n| match n.strip_suffix('/') {
                            Some(d) => json!({"name": d, "type": "dir"}),
                            None => json!({"name": n, "type": "file"}),
                        })
                        .collect();
                    json!({"type": "fs_dir", "entries": entries})
                } else {
                    json!({"type": "fs_error", "errno": "no-entry"})
                }
            }
            Some("fs_write") => {
                served.insert(path.clone(), text.to_string());
                json!({"type": "fs_done"})
            }
            Some("fs_remove") => match served.remove(&path) {
                Some(_) => json!({"type": "fs_done"}),
                None => json!({"type": "fs_error", "errno": "no-entry"}),
            },
            Some("publish") => {
                send(
                    &mut out,
                    json!({"body": {"type": "published", "value": body["value"]}}),
                );
                continue;
            }
            Some("version") => json!({"type": "version", "version": version}),
            Some("ordered") => json!({"type": "ordered", "n": body["n"], "version": version}),
            Some("write") => match std::fs::write(&path, text) {
                Ok(()) => json!({"type": "ok"}),
                Err(error) => io_error(error),
            },
            Some("mkdir") => match std::fs::create_dir_all(&path) {
                Ok(()) => json!({"type": "ok"}),
                Err(error) => io_error(error),
            },
            Some("rename") => match std::fs::rename(&path, body["to"].as_str().unwrap_or_default())
            {
                Ok(()) => json!({"type": "ok"}),
                Err(error) => io_error(error),
            },
            Some("open") => {
                let result = (|| -> io::Result<()> {
                    let mut file = std::fs::File::create(&path)?;
                    file.write_all(text.as_bytes())?;
                    open.insert(path.clone(), file);
                    Ok(())
                })();
                match result {
                    Ok(()) => json!({"type": "opened"}),
                    Err(error) => io_error(error),
                }
            }
            Some("close") => json!({"type": "closed", "closed": open.remove(&path).is_some()}),
            Some("arm-shutdown") => {
                emit_shutdown = true;
                json!({"type": "armed"})
            }
            Some("ignore-stdin") => json!({"type": "ignoring"}),
            Some("tcp") => match tcp_line(body["address"].as_str().unwrap_or_default(), text) {
                Ok(line) => json!({"type": "tcp", "line": line}),
                Err(error) => io_error(error),
            },
            Some("read") => match std::fs::read_to_string(&path) {
                Ok(text) => json!({"type": "content", "text": text}),
                Err(error) => io_error(error),
            },
            Some("list") => match std::fs::read_dir(&path) {
                Ok(entries) => {
                    let mut names: Vec<String> = entries
                        .filter_map(|entry| entry.ok())
                        .map(|entry| entry.file_name().to_string_lossy().to_string())
                        .collect();
                    names.sort();
                    json!({"type": "entries", "names": names})
                }
                Err(error) => io_error(error),
            },
            _ => json!({"type": "error", "error": "unknown message"}),
        };
        reply(&mut out, &message, response);
        if body["type"] == "ignore-stdin" {
            loop {
                std::thread::sleep(Duration::from_secs(60));
            }
        }
    }
 }
@@ -0,0 +1,555 @@
 //! Integration tests for the agent's inference and restart behavior.
 #[allow(dead_code)]
 mod common;
 use std::collections::HashMap;
 use std::path::PathBuf;
 use std::process::Command;
 use std::sync::OnceLock;
 use std::time::Duration;
 use common::{create_world, receive_message, receive_reply, request, source_with_test, start};
 use sausage::{Envelope, Host, World};
 use serde_json::{Value, json};
 use tokio::io::{AsyncReadExt, AsyncWriteExt};
 use tokio::net::{TcpListener, TcpStream};
 use tokio::sync::{mpsc, oneshot};
 use tokio::task::{JoinHandle, JoinSet};
 const APIS: [Api; 2] = [Api::OpenAi, Api::Anthropic];
 const TEST_TOKEN: &str = "fake-token";
 #[derive(Clone, Copy)]
 enum Api {
    OpenAi,
    Anthropic,
 }
 impl Api {
    fn name(self) -> &'static str {
        match self {
            Self::OpenAi => "openai-responses",
            Self::Anthropic => "anthropic-messages",
        }
    }
    fn path(self) -> &'static str {
        match self {
            Self::OpenAi => "/v1/responses",
            Self::Anthropic => "/v1/messages",
        }
    }
    fn text_response(self, text: &str) -> Value {
        match self {
            Self::OpenAi => {
                json!({"output": [{"type": "message", "content": [{"type": "output_text", "text": text}]}]})
            }
            Self::Anthropic => json!({"content": [{"type": "text", "text": text}]}),
        }
    }
    fn tool_response(self, id: &str, name: &str, arguments: &Value) -> Value {
        match self {
            Self::OpenAi => {
                json!({"output": [{"type": "function_call", "call_id": id, "name": name, "arguments": arguments.to_string()}]})
            }
            Self::Anthropic => {
                json!({"content": [{"type": "tool_use", "id": id, "name": name, "input": arguments}]})
            }
        }
    }
    fn check_request(self, request: &HttpRequest) {
        assert_eq!(request.method, "POST");
        assert_eq!(request.path, self.path());
        assert_eq!(request.headers["content-type"], "application/json");
        assert_eq!(request.body["model"], "fake-model");
        match self {
            Self::OpenAi => assert_eq!(request.headers["authorization"], "Bearer fake-token"),
            Self::Anthropic => {
                assert_eq!(request.headers["x-api-key"], TEST_TOKEN);
                assert_eq!(request.headers["anthropic-version"], "2023-06-01");
            }
        }
    }
 }
 struct HttpRequest {
    method: String,
    path: String,
    headers: HashMap<String, String>,
    body: Value,
 }
 enum ReplyPlan {
    Send(Value),
    Hold(Value, oneshot::Receiver<()>),
 }
 struct FakeServer {
    base_url: String,
    plans: mpsc::Sender<ReplyPlan>,
    requests: mpsc::Receiver<HttpRequest>,
    task: JoinHandle<()>,
 }
 impl FakeServer {
    async fn start() -> Self {
        let listener = TcpListener::bind("127.0.0.1:0").await.unwrap();
        let address = listener.local_addr().unwrap();
        let (plans, mut plan_rx) = mpsc::channel(16);
        let (request_tx, requests) = mpsc::channel(16);
        let task = tokio::spawn(async move {
            let mut handlers = JoinSet::new();
            loop {
                tokio::select! {
                    accepted = listener.accept() => {
                        let (mut stream, _) = accepted.expect("fake listener accept failed");
                        let request = read_http_request(&mut stream).await;
                        let Some(plan) = plan_rx.recv().await else { break };
                        if request_tx.send(request).await.is_err() {
                            break;
                        }
                        handlers.spawn(async move {
                            let (body, release) = match plan {
                                ReplyPlan::Send(body) => (body, None),
                                ReplyPlan::Hold(body, release) => (body, Some(release)),
                            };
                            if let Some(release) = release {
                                let _ = release.await;
                            }
                            write_http_response(stream, body).await;
                        });
                    }
                    Some(_) = handlers.join_next(), if !handlers.is_empty() => {}
                }
            }
        });
        Self {
            base_url: format!("http://127.0.0.1:{}", address.port()),
            plans,
            requests,
            task,
        }
    }
    async fn answer(&self, body: Value) {
        self.plans.send(ReplyPlan::Send(body)).await.unwrap();
    }
    async fn hold(&self, body: Value) -> oneshot::Sender<()> {
        let (release, wait) = oneshot::channel();
        self.plans.send(ReplyPlan::Hold(body, wait)).await.unwrap();
        release
    }
    async fn next_request(&mut self) -> HttpRequest {
        tokio::time::timeout(Duration::from_secs(20), self.requests.recv())
            .await
            .expect("timed out waiting for fake inference request")
            .expect("fake server request channel closed")
    }
 }
 impl Drop for FakeServer {
    fn drop(&mut self) {
        self.task.abort();
    }
 }
 async fn read_http_request(stream: &mut TcpStream) -> HttpRequest {
    let mut received = Vec::new();
    let mut chunk = [0; 4096];
    let header_end = loop {
        let count = stream.read(&mut chunk).await.expect("read HTTP request");
        assert_ne!(count, 0, "client closed before HTTP headers arrived");
        received.extend_from_slice(&chunk[..count]);
        if let Some(end) = received.windows(4).position(|part| part == b"\r\n\r\n") {
            break end;
        }
    };
    let header_text = String::from_utf8_lossy(&received[..header_end]);
    let mut lines = header_text.split("\r\n");
    let mut request_line = lines.next().unwrap().split_whitespace();
    let method = request_line.next().unwrap().to_string();
    let path = request_line.next().unwrap().to_string();
    let mut headers = HashMap::new();
    for line in lines {
        if let Some((name, value)) = line.split_once(':') {
            headers.insert(name.trim().to_ascii_lowercase(), value.trim().to_string());
        }
    }
    let body_start = header_end + 4;
    let request_body = if let Some(length) = headers.get("content-length") {
        let body_length = length.parse::<usize>().unwrap();
        while received.len() < body_start + body_length {
            let count = stream.read(&mut chunk).await.expect("read HTTP body");
            assert_ne!(count, 0, "client closed before HTTP body arrived");
            received.extend_from_slice(&chunk[..count]);
        }
        received[body_start..body_start + body_length].to_vec()
    } else {
        assert!(
            headers
                .get("transfer-encoding")
                .is_some_and(|value| value.eq_ignore_ascii_case("chunked")),
            "request has neither Content-Length nor chunked transfer encoding: {headers:?}"
        );
        read_chunked_body(stream, &mut received, body_start).await
    };
    let body = serde_json::from_slice(&request_body).unwrap();
    HttpRequest {
        method,
        path,
        headers,
        body,
    }
 }
 async fn read_chunked_body(
    stream: &mut TcpStream,
    received: &mut Vec<u8>,
    mut offset: usize,
 ) -> Vec<u8> {
    let mut body = Vec::new();
    loop {
        let line_end = loop {
            if let Some(end) = received[offset..]
                .windows(2)
                .position(|part| part == b"\r\n")
            {
                break offset + end;
            }
            let mut chunk = [0; 4096];
            let count = stream.read(&mut chunk).await.expect("read chunk size");
            assert_ne!(count, 0, "client closed before chunk size arrived");
            received.extend_from_slice(&chunk[..count]);
        };
        let size = String::from_utf8_lossy(&received[offset..line_end]);
        let size = size.split(';').next().unwrap().trim();
        let size = usize::from_str_radix(size, 16).unwrap();
        offset = line_end + 2;
        if size == 0 {
            return body;
        }
        while received.len() < offset + size + 2 {
            let mut chunk = [0; 4096];
            let count = stream.read(&mut chunk).await.expect("read chunk data");
            assert_ne!(count, 0, "client closed before chunk data arrived");
            received.extend_from_slice(&chunk[..count]);
        }
        body.extend_from_slice(&received[offset..offset + size]);
        assert_eq!(&received[offset + size..offset + size + 2], b"\r\n");
        offset += size + 2;
    }
 }
 async fn write_http_response(mut stream: TcpStream, body: Value) {
    let body = serde_json::to_vec(&body).unwrap();
    let head = format!(
        "HTTP/1.1 200 OK\r\ncontent-type: application/json\r\ncontent-length: {}\r\nconnection: close\r\n\r\n",
        body.len()
    );
    let mut response = head.into_bytes();
    response.extend_from_slice(&body);
    let _ = stream.write_all(&response).await;
    let _ = stream.shutdown().await;
 }
 fn agent_wasm() -> &'static PathBuf {
    static WASM: OnceLock<PathBuf> = OnceLock::new();
    WASM.get_or_init(|| {
        let root = common::repo_root();
        let output = Command::new("cargo")
            .args([
                "build",
                "--release",
                "-p",
                "agent",
                "--target",
                "wasm32-wasip2",
                "--target-dir",
                "target/test-actors",
            ])
            .current_dir(&root)
            .output()
            .expect("run cargo to build the agent actor");
        assert!(
            output.status.success(),
            "building agent failed\nstdout:\n{}\nstderr:\n{}",
            String::from_utf8_lossy(&output.stdout),
            String::from_utf8_lossy(&output.stderr)
        );
        let wasm = root.join("target/test-actors/wasm32-wasip2/release/agent.wasm");
        assert!(
            wasm.is_file(),
            "agent build did not create {}",
            wasm.display()
        );
        wasm
    })
 }
 async fn start_agent(
    api: Api,
    fake: &FakeServer,
    label: &str,
 ) -> (World, Host, mpsc::Receiver<Envelope>) {
    let world = create_world(label);
    let data = world.data_dir("agent");
    std::fs::create_dir_all(&data).unwrap();
    let config = json!({"api": api.name(), "base_url": fake.base_url, "model": "fake-model", "token": TEST_TOKEN});
    std::fs::write(
        data.join("config.json"),
        serde_json::to_vec(&config).unwrap(),
    )
    .unwrap();
    let source = source_with_test(
        &world,
        "agent-candidate",
        json!({"steps": [{"send": {"type": "text", "text": "candidate"}, "expect": {"type": "text"}}]}),
    );
    let (host, mut mailbox) = start(&world).await;
    let spawned = common::spawn_actor(&host, &mut mailbox, "agent", agent_wasm(), &source).await;
    assert_eq!(
        spawned.body["type"], "spawned",
        "agent spawn failed: {spawned:?}"
    );
    let subscribed = request(
        &host,
        &mut mailbox,
        json!({"type": "subscribe", "actor": "agent"}),
    )
    .await;
    assert_eq!(subscribed.body["type"], "subscribed");
    (world, host, mailbox)
 }
 fn send_text(host: &Host, text: &str) -> String {
    host.broker.send(
        "console",
        Some("agent"),
        None,
        None,
        json!({"type": "text", "text": text}),
    )
 }
 async fn assert_published_text(mailbox: &mut mpsc::Receiver<Envelope>, text: &str) {
    let message = receive_message(mailbox, Duration::from_secs(20)).await;
    assert_eq!(message.from, "agent");
    assert_eq!(message.to, "console");
    assert_eq!(message.reply_to, None);
    assert_eq!(message.body, json!({"type": "text", "text": text}));
 }
 fn history(world: &World) -> Vec<Value> {
    std::fs::read_to_string(world.data_dir("agent").join("history.jsonl"))
        .unwrap()
        .lines()
        .map(|line| serde_json::from_str(line).unwrap())
        .collect()
 }
 fn assert_history_tools_have_results(history: &[Value]) {
    let calls: Vec<_> = history
        .iter()
        .filter(|entry| entry["kind"] == "tool_call")
        .collect();
    let results: Vec<_> = history
        .iter()
        .filter(|entry| entry["kind"] == "tool_result")
        .collect();
    assert_eq!(calls.len(), results.len());
    for call in calls {
        assert!(
            results.iter().any(|result| result["id"] == call["id"]),
            "tool call has no result: {call}"
        );
    }
 }
 fn assert_tool_pair(
    request: &HttpRequest,
    api: Api,
    id: &str,
    name: &str,
    arguments: &Value,
 ) -> String {
    match api {
        Api::OpenAi => {
            let input = request.body["input"].as_array().unwrap();
            let call_index = input
                .iter()
                .position(|item| item["type"] == "function_call")
                .unwrap();
            let result_index = input
                .iter()
                .position(|item| item["type"] == "function_call_output")
                .unwrap();
            assert!(call_index < result_index);
            let call = &input[call_index];
            assert_eq!(call["call_id"], id);
            assert_eq!(call["name"], name);
            assert_eq!(
                serde_json::from_str::<Value>(call["arguments"].as_str().unwrap()).unwrap(),
                *arguments
            );
            let result = &input[result_index];
            assert_eq!(result["call_id"], id);
            result["output"].as_str().unwrap().to_string()
        }
        Api::Anthropic => {
            let messages = request.body["messages"].as_array().unwrap();
            let mut call_position = None;
            let mut result_position = None;
            let mut call = None;
            let mut result = None;
            for (index, message) in messages.iter().enumerate() {
                let Some(blocks) = message["content"].as_array() else {
                    continue;
                };
                for block in blocks {
                    match block["type"].as_str() {
                        Some("tool_use") => {
                            call_position = Some(index);
                            call = Some(block);
                        }
                        Some("tool_result") => {
                            result_position = Some(index);
                            result = Some(block);
                        }
                        _ => {}
                    }
                }
            }
            assert!(call_position.unwrap() < result_position.unwrap());
            let call = call.unwrap();
            assert_eq!(call["id"], id);
            assert_eq!(call["name"], name);
            assert_eq!(call["input"], *arguments);
            let result = result.unwrap();
            assert_eq!(result["tool_use_id"], id);
            result["content"].as_str().unwrap().to_string()
        }
    }
 }
 #[tokio::test]
 async fn text_answers_use_both_inference_apis() {
    for api in APIS {
        let mut fake = FakeServer::start().await;
        fake.answer(api.text_response("hello from the fake model"))
            .await;
        let (_, host, mut mailbox) =
            start_agent(api, &fake, &format!("agent-text-{}", api.name())).await;
        send_text(&host, "say hello");
        api.check_request(&fake.next_request().await);
        assert_published_text(&mut mailbox, "hello from the fake model").await;
        host.stop().await;
    }
 }
 #[tokio::test]
 async fn tool_calls_pair_with_results_in_both_inference_apis() {
    let args = json!({"path": "/actor"});
    for api in APIS {
        let mut fake = FakeServer::start().await;
        fake.answer(api.tool_response("list-1", "list_dir", &args))
            .await;
        let (world, host, mut mailbox) =
            start_agent(api, &fake, &format!("agent-tools-{}", api.name())).await;
        send_text(&host, "list actors");
        api.check_request(&fake.next_request().await);
        fake.answer(api.text_response("the actor list is ready"))
            .await;
        let second = fake.next_request().await;
        api.check_request(&second);
        let output = assert_tool_pair(&second, api, "list-1", "list_dir", &args);
        let result: Value = serde_json::from_str(&output).unwrap();
        assert!(
            result["entries"]
                .as_array()
                .unwrap()
                .iter()
                .any(|entry| entry["name"] == "agent")
        );
        assert_published_text(&mut mailbox, "the actor list is ready").await;
        host.stop().await;
        let history = history(&world);
        assert_eq!(
            history
                .iter()
                .map(|entry| entry["kind"].as_str().unwrap())
                .collect::<Vec<_>>(),
            ["user", "tool_call", "tool_result", "assistant"]
        );
        assert_eq!(history[1]["id"], "list-1");
        assert_eq!(history[2]["id"], "list-1");
    }
 }
 #[tokio::test]
 async fn restart_resumes_a_turn_with_completed_tool_history() {
    let args = json!({"path": "/actor"});
    for api in [Api::OpenAi] {
        let mut fake = FakeServer::start().await;
        fake.answer(api.tool_response("list-1", "list_dir", &args))
            .await;
        let (world, host, mut mailbox) =
            start_agent(api, &fake, &format!("agent-resume-{}", api.name())).await;
        let id = send_text(&host, "list actors before the restart");
        api.check_request(&fake.next_request().await);
        let release = fake.hold(api.text_response("discarded response")).await;
        let second = fake.next_request().await;
        api.check_request(&second);
        assert_tool_pair(&second, api, "list-1", "list_dir", &args);
        let stopped = request(
            &host,
            &mut mailbox,
            json!({"type": "stop", "actor": "agent"}),
        )
        .await;
        assert_eq!(stopped.body["type"], "stopped");
        assert_eq!(
            serde_json::from_slice::<Value>(
                &std::fs::read(world.data_dir("agent").join("turn.json")).unwrap()
            )
            .unwrap(),
            json!(true)
        );
        let _ = release.send(());
        fake.answer(api.text_response("resumed answer")).await;
        let start_id = host.broker.send(
            "console",
            Some("broker"),
            None,
            None,
            json!({"type": "start", "actor": "agent"}),
        );
        let resumed = fake.next_request().await;
        api.check_request(&resumed);
        assert_tool_pair(&resumed, api, "list-1", "list_dir", &args);
        let started = receive_reply(&mut mailbox, &start_id, Duration::from_secs(20)).await;
        assert_eq!(started.body["type"], "started");
        assert_published_text(&mut mailbox, "resumed answer").await;
        let history = history(&world);
        assert_history_tools_have_results(&history);
        assert_eq!(
            history
                .iter()
                .filter(|entry| entry["kind"] == "user"
                    && entry["text"].as_str().unwrap_or_default().contains(&id))
                .count(),
            1
        );
        host.stop().await;
    }
 }
@@ -0,0 +1,248 @@
 use std::path::{Path, PathBuf};
 use std::process::Command;
 use std::sync::OnceLock;
 use std::sync::atomic::{AtomicU64, Ordering};
 use std::time::{Duration, SystemTime, UNIX_EPOCH};
 use sausage::{Envelope, Host, World};
 use serde_json::{Value, json};
 use tokio::sync::mpsc;
 const REPLY_TIMEOUT: Duration = Duration::from_secs(10);
 static WORLD_SEQUENCE: AtomicU64 = AtomicU64::new(0);
 pub fn repo_root() -> PathBuf {
    PathBuf::from(env!("CARGO_MANIFEST_DIR"))
        .parent()
        .unwrap()
        .to_path_buf()
 }
 pub fn create_world(label: &str) -> World {
    let nonce = SystemTime::now()
        .duration_since(UNIX_EPOCH)
        .unwrap()
        .as_nanos();
    let sequence = WORLD_SEQUENCE.fetch_add(1, Ordering::Relaxed);
    let path = repo_root()
        .join("target/test-worlds")
        .join(format!("{label}-{}-{nonce}-{sequence}", std::process::id()));
    World::create(&path).unwrap()
 }
 pub fn actor_fixture_source(name: &str) -> PathBuf {
    repo_root().join("cli/tests/actors").join(name)
 }
 pub fn cargo_source(name: &str) -> PathBuf {
    repo_root().join("cli/tests/crates").join(name)
 }
 pub fn toolbox_wasm() -> &'static PathBuf {
    static WASM: OnceLock<PathBuf> = OnceLock::new();
    WASM.get_or_init(|| build_fixture("toolbox"))
 }
 fn build_fixture(name: &str) -> PathBuf {
    let root = repo_root();
    let manifest = actor_fixture_source(name).join("Cargo.toml");
    let target_dir = root.join("target/test-actors");
    let output = Command::new("cargo")
        .args([
            "build",
            "--release",
            "--target",
            "wasm32-wasip2",
            "--target-dir",
        ])
        .arg(&target_dir)
        .arg("--manifest-path")
        .arg(&manifest)
        .current_dir(&root)
        .output()
        .expect("run cargo to build the test actor");
    assert!(
        output.status.success(),
        "building fixture {name} failed\nstdout:\n{}\nstderr:\n{}",
        String::from_utf8_lossy(&output.stdout),
        String::from_utf8_lossy(&output.stderr)
    );
    let wasm = target_dir
        .join("wasm32-wasip2/release")
        .join(format!("{name}.wasm"));
    assert!(
        wasm.is_file(),
        "fixture build did not create {}",
        wasm.display()
    );
    wasm
 }
 pub fn passing_source(world: &World, name: &str) -> PathBuf {
    source_with_test(
        world,
        name,
        json!({
            "steps": [{
                "send": {"type": "echo", "value": "candidate"},
                "expect": {"type": "echo", "value": "candidate"}
            }]
        }),
    )
 }
 pub fn source_with_test(world: &World, name: &str, test: Value) -> PathBuf {
    let source = world.source_dir("console").join("test-fixtures").join(name);
    std::fs::create_dir_all(source.join("tests")).unwrap();
    std::fs::write(
        source.join("tests/candidate.json"),
        serde_json::to_vec(&test).unwrap(),
    )
    .unwrap();
    source
 }
 pub async fn start(world: &World) -> (Host, mpsc::Receiver<Envelope>) {
    let host = Host::start(&world.root).await.unwrap();
    let mailbox = host.mailbox("console");
    (host, mailbox)
 }
 pub async fn request(host: &Host, mailbox: &mut mpsc::Receiver<Envelope>, body: Value) -> Envelope {
    let id = host
        .broker
        .send("console", Some("broker"), None, None, body);
    receive_reply(mailbox, &id, REPLY_TIMEOUT).await
 }
 pub async fn receive_message(
    mailbox: &mut mpsc::Receiver<Envelope>,
    timeout: Duration,
 ) -> Envelope {
    tokio::time::timeout(timeout, mailbox.recv())
        .await
        .expect("timed out waiting for a message")
        .expect("console mailbox closed")
 }
 pub async fn receive_reply(
    mailbox: &mut mpsc::Receiver<Envelope>,
    id: &str,
    timeout: Duration,
 ) -> Envelope {
    tokio::time::timeout(timeout, async {
        loop {
            let envelope = mailbox.recv().await.expect("console mailbox closed");
            if envelope.reply_to.as_deref() == Some(id) {
                return envelope;
            }
        }
    })
    .await
    .unwrap_or_else(|_| panic!("timed out waiting for reply to {id}"))
 }
 pub async fn receive_replies(
    mailbox: &mut mpsc::Receiver<Envelope>,
    ids: &[String],
    timeout: Duration,
 ) -> Vec<Envelope> {
    let mut replies = Vec::with_capacity(ids.len());
    tokio::time::timeout(timeout, async {
        while replies.len() < ids.len() {
            let message = mailbox.recv().await.expect("console mailbox closed");
            assert!(
                ids.iter()
                    .any(|id| message.reply_to.as_deref() == Some(id.as_str())),
                "unexpected message while waiting for replies: {message:?}"
            );
            replies.push(message);
        }
    })
    .await
    .expect("timed out waiting for replies");
    replies
 }
 pub async fn ask(
    host: &Host,
    mailbox: &mut mpsc::Receiver<Envelope>,
    actor: &str,
    body: Value,
 ) -> Envelope {
    let id = host.broker.send("console", Some(actor), None, None, body);
    receive_reply(mailbox, &id, REPLY_TIMEOUT).await
 }
 pub async fn ask_type(
    host: &Host,
    mailbox: &mut mpsc::Receiver<Envelope>,
    actor: &str,
    body: Value,
    expected: &str,
 ) -> Envelope {
    let reply = ask(host, mailbox, actor, body).await;
    assert_eq!(reply.body["type"], expected, "unexpected reply: {reply:?}");
    reply
 }
 pub fn spawn_request(host: &Host, actor: &str, wasm: &Path, source: &Path) -> String {
    host.broker.send(
        "console",
        Some("broker"),
        None,
        None,
        json!({
            "type": "spawn",
            "actor": actor,
            "wasm": wasm.display().to_string(),
            "source": source.display().to_string()
        }),
    )
 }
 pub async fn spawn_actor(
    host: &Host,
    mailbox: &mut mpsc::Receiver<Envelope>,
    actor: &str,
    wasm: &Path,
    source: &Path,
 ) -> Envelope {
    let id = spawn_request(host, actor, wasm, source);
    receive_reply(mailbox, &id, REPLY_TIMEOUT).await
 }
 pub async fn spawn_type(
    host: &Host,
    mailbox: &mut mpsc::Receiver<Envelope>,
    actor: &str,
    wasm: &Path,
    source: &Path,
 ) -> Envelope {
    let reply = spawn_actor(host, mailbox, actor, wasm, source).await;
    assert_eq!(
        reply.body["type"], "spawned",
        "unexpected spawn reply: {reply:?}"
    );
    reply
 }
 pub async fn upgrade_actor(
    host: &Host,
    mailbox: &mut mpsc::Receiver<Envelope>,
    actor: &str,
    wasm: &Path,
    source: &Path,
 ) -> Envelope {
    request(
        host,
        mailbox,
        json!({
            "type": "upgrade",
            "actor": actor,
            "wasm": wasm.display().to_string(),
            "source": source.display().to_string()
        }),
    )
    .await
 }
@@ -1,6 +1,6 @@
 [package]
-name = "crasher"
+name = "cargo-fail"
 version = "0.1.0"
 edition = "2024"
-[dependencies]
+[workspace]
@@ -0,0 +1,3 @@
 fn main() {
    missing_function();
 }
@@ -1,7 +1,6 @@
 [package]
-name = "echo"
+name = "cargo-valid"
 version = "0.1.0"
 edition = "2024"
-[dependencies]
+[workspace]
 serde_json = "1"
@@ -0,0 +1 @@
 fn main() {}
@@ -0,0 +1,911 @@
 mod common;
 use std::time::Duration;
 use common::*;
 use sausage::{Envelope, Host, World};
 use serde_json::{Value, json};
 use tokio::sync::mpsc;
 async fn filesystem_world(label: &str) -> (World, Host, mpsc::Receiver<Envelope>) {
    let world = create_world(label);
    let wasm = toolbox_wasm().clone();
    let (host, mut mailbox) = start(&world).await;
    for actor in ["writer", "reader"] {
        let source = passing_source(&world, actor);
        let spawned = spawn_actor(&host, &mut mailbox, actor, &wasm, &source).await;
        assert_eq!(spawned.body["type"], "spawned");
    }
    (world, host, mailbox)
 }
 async fn receive_shutdown_messages(
    mailbox: &mut mpsc::Receiver<Envelope>,
    id: &str,
    expected: &str,
 ) {
    let (mut result, mut reply, mut publish) = (false, false, false);
    tokio::time::timeout(Duration::from_secs(10), async {
        while !result || !reply || !publish {
            let message = mailbox.recv().await.expect("console mailbox closed");
            if message.reply_to.as_deref() == Some(id) {
                assert_eq!(message.body["type"], expected);
                result = true;
            } else if message.reply_to.as_deref() == Some("broker/shutdown") {
                assert_eq!(message.from, "shutdown-output");
                assert_eq!(message.body["type"], "shutdown-reply");
                reply = true;
            } else {
                assert_eq!(message.from, "shutdown-output");
                assert_eq!(message.reply_to, None);
                assert_eq!(message.body["type"], "shutdown-publish");
                publish = true;
            }
        }
    })
    .await
    .expect("shutdown output or lifecycle reply did not arrive");
 }
 #[tokio::test]
 async fn routes_replies_publishes_and_reports_undeliverable() {
    let world = create_world("routing");
    let wasm = toolbox_wasm().clone();
    let (host, mut mailbox) = start(&world).await;
    let missing_id = host.broker.send(
        "console",
        Some("missing"),
        None,
        None,
        json!({"type": "hello"}),
    );
    let missing = receive_reply(&mut mailbox, &missing_id, Duration::from_secs(10)).await;
    assert_eq!(missing.body["type"], "undeliverable");
    assert_eq!(missing.body["to"], "missing");
    let source = passing_source(&world, "router");
    let spawned = spawn_actor(&host, &mut mailbox, "router", &wasm, &source).await;
    assert_eq!(spawned.body["type"], "spawned");
    let echo = ask(
        &host,
        &mut mailbox,
        "router",
        json!({"type": "echo", "value": "hello"}),
    )
    .await;
    assert_eq!(echo.from, "router");
    assert_eq!(echo.body, json!({"type": "echo", "value": "hello"}));
    let subscribed = request(
        &host,
        &mut mailbox,
        json!({"type": "subscribe", "actor": "router"}),
    )
    .await;
    assert_eq!(subscribed.body["type"], "subscribed");
    host.broker.send(
        "console",
        Some("router"),
        None,
        None,
        json!({"type": "publish", "value": "news"}),
    );
    let published = receive_message(&mut mailbox, Duration::from_secs(10)).await;
    assert_eq!(published.from, "router");
    assert_eq!(
        published.body,
        json!({"type": "published", "value": "news"})
    );
    assert_eq!(published.reply_to, None);
    host.stop().await;
 }
 #[tokio::test]
 async fn broker_does_not_answer_messages_with_reply_to() {
    let world = create_world("broker-reply-to");
    let (host, mut mailbox) = start(&world).await;
    let scanned = request(&host, &mut mailbox, json!({"type": "scan"})).await;
    assert_eq!(scanned.body["type"], "scanned");
    host.broker.send(
        "console",
        Some("broker"),
        None,
        Some("upstream-message"),
        json!({"type": "scan"}),
    );
    assert!(
        tokio::time::timeout(Duration::from_secs(1), mailbox.recv())
            .await
            .is_err(),
        "broker replied to a message that already had reply_to"
    );
    host.stop().await;
 }
 #[tokio::test]
 async fn exit_request_is_answered_and_signals_the_host() {
    let world = create_world("broker-exit");
    let (host, mut mailbox) = start(&world).await;
    let exiting = request(&host, &mut mailbox, json!({"type": "exit"})).await;
    assert_eq!(exiting.body["type"], "exiting");
    tokio::time::timeout(Duration::from_secs(1), host.broker.exit_requested())
        .await
        .expect("exit request did not reach the host");
    host.stop().await;
 }
 #[tokio::test]
 async fn filesystem_permissions_and_public_sharing() {
    let (_, host, mut mailbox) = filesystem_world("filesystem-permissions").await;
    for path in [
        "/actor/reader/public/denied.txt",
        "/actor/writer/public/denied.txt",
    ] {
        let denied = ask(
            &host,
            &mut mailbox,
            "writer",
            json!({"type": "write", "path": path, "text": "denied"}),
        )
        .await;
        assert_eq!(denied.body["type"], "error", "write to {path} succeeded");
    }
    let written = ask(
        &host,
        &mut mailbox,
        "writer",
        json!({"type": "write", "path": "/public/shared.txt", "text": "public"}),
    )
    .await;
    assert_eq!(written.body["type"], "ok");
    let shared = ask(
        &host,
        &mut mailbox,
        "reader",
        json!({"type": "read", "path": "/actor/writer/public/shared.txt"}),
    )
    .await;
    assert_eq!(shared.body, json!({"type": "content", "text": "public"}));
    host.stop().await;
 }
 #[tokio::test]
 async fn actors_can_read_but_not_write_other_actor_data() {
    let (_, host, mut mailbox) = filesystem_world("actor-data-sharing").await;
    ask_type(
        &host,
        &mut mailbox,
        "writer",
        json!({"type": "write", "path": "/data/x", "text": "shared"}),
        "ok",
    )
    .await;
    let shared = ask_type(
        &host,
        &mut mailbox,
        "reader",
        json!({"type": "read", "path": "/actor/writer/data/x"}),
        "content",
    )
    .await;
    assert_eq!(shared.body["text"], "shared");
    ask_type(
        &host,
        &mut mailbox,
        "reader",
        json!({"type": "write", "path": "/actor/writer/data/x", "text": "changed"}),
        "error",
    )
    .await;
    let unchanged = ask_type(
        &host,
        &mut mailbox,
        "writer",
        json!({"type": "read", "path": "/data/x"}),
        "content",
    )
    .await;
    assert_eq!(unchanged.body["text"], "shared");
    host.stop().await;
 }
 #[tokio::test]
 async fn actors_serve_files_under_fs() {
    // "writer" serves its fs/ from memory (toolbox fs_read / fs_write / fs_remove).
    let (_, host, mut mailbox) = filesystem_world("actor-fs").await;
    let file = "/actor/writer/fs/notes/a.txt";
    let write = json!({"type": "write", "path": file, "text": "hello"});
    ask_type(&host, &mut mailbox, "reader", write, "ok").await;
    // The write reached the owner as one fs_write message.
    let direct = json!({"type": "fs_read", "path": "/notes/a.txt"});
    let served = ask_type(&host, &mut mailbox, "writer", direct, "fs_file").await;
    assert_eq!(served.body["text"], "hello");
    let read = json!({"type": "read", "path": file});
    assert_eq!(ask_type(&host, &mut mailbox, "reader", read, "content").await.body["text"], "hello");
    let list = json!({"type": "list", "path": "/actor/writer/fs/notes"});
    assert_eq!(ask_type(&host, &mut mailbox, "reader", list, "entries").await.body["names"], json!(["a.txt"]));
    let root = json!({"type": "list", "path": "/actor/writer/fs"});
    assert_eq!(ask_type(&host, &mut mailbox, "reader", root, "entries").await.body["names"], json!(["notes"]));
    // fs_error and undeliverable become errors of the file operation.
    for path in ["/actor/writer/fs/missing.txt", "/actor/nobody/fs/x"] {
        ask_type(&host, &mut mailbox, "reader", json!({"type": "read", "path": path}), "error").await;
    }
    // An actor that does not answer (here: it is busy reading itself) fails after the timeout.
    let id = host.broker.send("console", Some("reader"), None, None, json!({"type": "read", "path": "/actor/reader/fs/x"}));
    let timed_out = receive_reply(&mut mailbox, &id, Duration::from_secs(20)).await;
    assert_eq!(timed_out.body["type"], "error");
    host.stop().await;
 }
 #[tokio::test]
 async fn files_are_plain_posix_files() {
    let (_, host, mut mailbox) = filesystem_world("posix").await;
    // An open file is visible by path, to the writer and to every reader.
    let open = json!({"type": "open", "path": "/public/new.txt", "text": "new"});
    ask_type(&host, &mut mailbox, "writer", open, "opened").await;
    let own = json!({"type": "read", "path": "/public/new.txt"});
    assert_eq!(ask_type(&host, &mut mailbox, "writer", own, "content").await.body["text"], "new");
    let other = json!({"type": "read", "path": "/actor/writer/public/new.txt"});
    assert_eq!(ask_type(&host, &mut mailbox, "reader", other, "content").await.body["text"], "new");
    // It can be renamed while open.
    let rename = json!({"type": "rename", "path": "/public/new.txt", "to": "/public/moved.txt"});
    ask_type(&host, &mut mailbox, "writer", rename, "ok").await;
    ask_type(&host, &mut mailbox, "writer", json!({"type": "close", "path": "/public/new.txt"}), "closed").await;
    let moved = json!({"type": "read", "path": "/actor/writer/public/moved.txt"});
    assert_eq!(ask_type(&host, &mut mailbox, "reader", moved, "content").await.body["text"], "new");
    host.stop().await;
 }
 #[tokio::test]
 async fn filesystem_rejects_paths_that_escape_data() {
    let (_, host, mut mailbox) = filesystem_world("filesystem-path-escape").await;
    let escaped = ask(
        &host,
        &mut mailbox,
        "writer",
        json!({"type": "write", "path": "/data/../../..", "text": "outside"}),
    )
    .await;
    assert_eq!(escaped.body["type"], "error");
    host.stop().await;
 }
 #[tokio::test]
 async fn upgrades_test_candidates_keep_old_versions_and_queue_messages_in_order() {
    let world = create_world("upgrade");
    let wasm = toolbox_wasm().clone();
    let (host, mut mailbox) = start(&world).await;
    let passing = passing_source(&world, "passing");
    let failing = source_with_test(
        &world,
        "failing",
        json!({
            "steps": [{
                "send": {"type": "echo", "value": "candidate"},
                "expect": {"type": "wrong"}
            }]
        }),
    );
    assert_eq!(
        spawn_actor(&host, &mut mailbox, "queue", &wasm, &passing)
            .await
            .body["type"],
        "spawned"
    );
    let failed = upgrade_actor(&host, &mut mailbox, "queue", &wasm, &failing).await;
    assert_eq!(failed.body["type"], "error");
    let old_version = ask(&host, &mut mailbox, "queue", json!({"type": "version"})).await;
    assert_eq!(old_version.body["version"], "1");
    // A version that fails its tests never enters versions/.
    assert!(!world.actor_dir("queue").join("versions/2").exists());
    let upgrade_id = host.broker.send(
        "console",
        Some("broker"),
        None,
        None,
        json!({"type": "upgrade", "actor": "queue", "wasm": wasm.display().to_string(), "source": passing.display().to_string()}),
    );
    tokio::time::timeout(Duration::from_secs(10), async {
        while !world.data_dir("queue").join("shutdown").is_file() {
            tokio::time::sleep(Duration::from_millis(10)).await;
        }
    })
    .await
    .expect("old actor did not enter shutdown during upgrade");
    let mut message_ids = Vec::new();
    for n in 1..=3 {
        message_ids.push(host.broker.send(
            "console",
            Some("queue"),
            None,
            None,
            json!({"type": "ordered", "n": n}),
        ));
    }
    let mut upgrade_result = None;
    let mut actor_replies = Vec::new();
    tokio::time::timeout(Duration::from_secs(15), async {
        while upgrade_result.is_none() || actor_replies.len() < message_ids.len() {
            let envelope = mailbox.recv().await.expect("console mailbox closed");
            if envelope.reply_to.as_deref() == Some(upgrade_id.as_str()) {
                upgrade_result = Some(envelope);
            } else if message_ids
                .iter()
                .any(|id| envelope.reply_to.as_deref() == Some(id.as_str()))
            {
                actor_replies.push(envelope);
            } else {
                panic!("unexpected message during queued upgrade: {envelope:?}");
            }
        }
    })
    .await
    .expect("upgrade did not deliver queued messages");
    assert_eq!(upgrade_result.unwrap().body["type"], "upgraded");
    let actual_ids: Vec<String> = actor_replies
        .iter()
        .map(|message| message.reply_to.clone().unwrap())
        .collect();
    assert_eq!(actual_ids, message_ids);
    for (index, envelope) in actor_replies.iter().enumerate() {
        assert_eq!(envelope.from, "queue");
        assert_eq!(envelope.body["type"], "ordered");
        assert_eq!(envelope.body["n"], json!(index + 1));
        assert_eq!(envelope.body["version"], "2");
    }
    host.stop().await;
 }
 #[tokio::test]
 async fn rolls_back_a_crash_loop_to_the_previous_version_without_restoring_data() {
    let world = create_world("crash-loop");
    let wasm = toolbox_wasm().clone();
    let (host, mut mailbox) = start(&world).await;
    let source = passing_source(&world, "source");
    assert_eq!(
        spawn_actor(&host, &mut mailbox, "crashloop", &wasm, &source)
            .await
            .body["type"],
        "spawned"
    );
    assert_eq!(
        ask(
            &host,
            &mut mailbox,
            "crashloop",
            json!({"type": "write", "path": "/data/state", "text": "stable"})
        )
        .await
        .body["type"],
        "ok"
    );
    let upgrade_id = host.broker.send(
        "console",
        Some("broker"),
        None,
        None,
        json!({"type": "upgrade", "actor": "crashloop", "wasm": wasm.display().to_string(), "source": source.display().to_string()}),
    );
    let mut upgraded: Option<Value> = None;
    let mut rolled_back: Option<Value> = None;
    tokio::time::timeout(Duration::from_secs(35), async {
        while upgraded.is_none() || rolled_back.is_none() {
            let envelope = mailbox.recv().await.expect("console mailbox closed");
            let kind = envelope.body["type"].as_str().map(str::to_string);
            match kind.as_deref() {
                Some("upgraded") if envelope.reply_to.as_deref() == Some(upgrade_id.as_str()) => {
                    upgraded = Some(envelope.body);
                }
                Some("rolled_back") => rolled_back = Some(envelope.body),
                other => panic!("unexpected automatic rollback message: {other:?}, {envelope:?}"),
            }
        }
    })
    .await
    .expect("crash loop did not trigger automatic rollback");
    assert_eq!(upgraded.unwrap()["version"], 2);
    let rollback = rolled_back.unwrap();
    assert_eq!(rollback["actor"], "crashloop");
    assert_eq!(rollback["from"], 2);
    assert_eq!(rollback["to"], 1);
    assert_eq!(rollback["reason"], "crash loop after upgrade");
    let version = ask(&host, &mut mailbox, "crashloop", json!({"type": "version"})).await;
    assert_eq!(version.body["version"], "1");
    let current = ask(
        &host,
        &mut mailbox,
        "crashloop",
        json!({"type": "read", "path": "/data/state"}),
    )
    .await;
    assert_eq!(current.body["text"], "bad-v2");
    host.stop().await;
 }
 #[tokio::test]
 async fn explicit_rollback_keeps_current_data() {
    let world = create_world("explicit-rollback");
    let wasm = toolbox_wasm().clone();
    let (host, mut mailbox) = start(&world).await;
    let source = passing_source(&world, "source");
    assert_eq!(
        spawn_actor(&host, &mut mailbox, "recover", &wasm, &source)
            .await
            .body["type"],
        "spawned"
    );
    ask(
        &host,
        &mut mailbox,
        "recover",
        json!({"type": "write", "path": "/data/state", "text": "version-one"}),
    )
    .await;
    let upgraded = upgrade_actor(&host, &mut mailbox, "recover", &wasm, &source).await;
    assert_eq!(upgraded.body["type"], "upgraded");
    ask(
        &host,
        &mut mailbox,
        "recover",
        json!({"type": "write", "path": "/data/state", "text": "version-two"}),
    )
    .await;
    let rolled_back = request(
        &host,
        &mut mailbox,
        json!({"type": "rollback", "actor": "recover", "version": 1}),
    )
    .await;
    assert_eq!(rolled_back.body["type"], "rolled_back");
    assert_eq!(rolled_back.body["from"], 2);
    assert_eq!(rolled_back.body["to"], 1);
    let version = ask(&host, &mut mailbox, "recover", json!({"type": "version"})).await;
    assert_eq!(version.body["version"], "1");
    let current = ask(
        &host,
        &mut mailbox,
        "recover",
        json!({"type": "read", "path": "/data/state"}),
    )
    .await;
    assert_eq!(current.body["text"], "version-two");
    host.stop().await;
 }
 #[tokio::test]
 async fn remove_shuts_an_actor_down_and_deletes_its_folder() {
    let world = create_world("remove");
    let wasm = toolbox_wasm().clone();
    let (host, mut mailbox) = start(&world).await;
    let source = passing_source(&world, "source");
    spawn_type(&host, &mut mailbox, "doomed", &wasm, &source).await;
    let write = json!({"type": "write", "path": "/data/state", "text": "x"});
    ask_type(&host, &mut mailbox, "doomed", write, "ok").await;
    ask_type(&host, &mut mailbox, "doomed", json!({"type": "arm-shutdown"}), "armed").await;
    // Normal shutdown: the actor gets "shutdown" and its last message is routed.
    let id = host.broker.send("console", Some("broker"), None, None, json!({"type": "remove", "actor": "doomed"}));
    let (mut removed, mut last_words) = (false, false);
    tokio::time::timeout(Duration::from_secs(10), async {
        while !removed || !last_words {
            let message = mailbox.recv().await.expect("console mailbox closed");
            if message.reply_to.as_deref() == Some(id.as_str()) {
                assert_eq!(message.body, json!({"type": "removed", "actor": "doomed"}));
                removed = true;
            } else if message.reply_to.as_deref() == Some("broker/shutdown") {
                assert_eq!(message.body["type"], "shutdown-reply");
                last_words = true;
            }
        }
    })
    .await
    .expect("remove did not answer or did not shut the actor down");
    assert!(!world.actor_dir("doomed").exists());
    let gone = ask(&host, &mut mailbox, "doomed", json!({"type": "echo", "value": "hi"})).await;
    assert_eq!(gone.body["type"], "undeliverable");
    let again = request(&host, &mut mailbox, json!({"type": "remove", "actor": "doomed"})).await;
    assert_eq!(again.body["type"], "error");
    let broker = request(&host, &mut mailbox, json!({"type": "remove", "actor": "broker"})).await;
    assert_eq!(broker.body["type"], "error");
    assert!(world.actor_dir("broker").exists());
    // The ID is free again: a new spawn starts at version 1 with empty data.
    assert_eq!(spawn_type(&host, &mut mailbox, "doomed", &wasm, &source).await.body["version"], 1);
    let read = json!({"type": "read", "path": "/data/state"});
    ask_type(&host, &mut mailbox, "doomed", read, "error").await;
    host.stop().await;
 }
 #[tokio::test]
 async fn unknown_broker_request_lists_the_known_ones() {
    let world = create_world("unknown-request");
    let (host, mut mailbox) = start(&world).await;
    let unknown = request(&host, &mut mailbox, json!({"type": "frobnicate"})).await;
    assert_eq!(unknown.body["type"], "error");
    let reason = unknown.body["reason"].as_str().unwrap();
    assert!(reason.contains("remove") && reason.contains("tap"), "{reason}");
    host.stop().await;
 }
 #[tokio::test]
 async fn cargo_actor_builds_valid_crates_and_reports_compiler_errors() {
    let world = create_world("cargo-actor");
    let (host, mut mailbox) = start(&world).await;
    let valid_source = cargo_source("cargo-valid");
    let valid_id = host.broker.send(
        "console",
        Some("cargo"),
        None,
        None,
        json!({"type": "build", "source": valid_source.display().to_string()}),
    );
    let built = receive_reply(&mut mailbox, &valid_id, Duration::from_secs(120)).await;
    assert_eq!(built.body["type"], "built");
    let wasm = built.body["wasm"].as_str().unwrap();
    assert!(wasm.ends_with(".wasm"));
    assert!(host.world.resolve("console", wasm).unwrap().is_file());
    let invalid_source = cargo_source("cargo-fail");
    let invalid_id = host.broker.send(
        "console",
        Some("cargo"),
        None,
        None,
        json!({"type": "build", "source": invalid_source.display().to_string()}),
    );
    let failed = receive_reply(&mut mailbox, &invalid_id, Duration::from_secs(120)).await;
    assert_eq!(failed.body["type"], "build_failed");
    assert!(
        failed.body["errors"]
            .as_str()
            .unwrap()
            .contains("missing_function")
    );
    host.stop().await;
 }
 #[tokio::test]
 async fn rejects_invalid_actor_ids() {
    let world = create_world("invalid-id");
    let wasm = toolbox_wasm().clone();
    let (host, mut mailbox) = start(&world).await;
    let invalid = request(
        &host,
        &mut mailbox,
        json!({"type": "spawn", "actor": "bad/actor", "wasm": wasm.display().to_string()}),
    )
    .await;
    assert_eq!(invalid.body["type"], "error");
    assert!(
        invalid.body["reason"]
            .as_str()
            .unwrap()
            .contains("invalid actor ID")
    );
    host.stop().await;
 }
 #[tokio::test]
 async fn rejects_parent_paths() {
    let world = create_world("parent-path");
    let (host, mut mailbox) = start(&world).await;
    let parent_path = request(
        &host,
        &mut mailbox,
        json!({"type": "spawn", "actor": "safe", "wasm": "/public/../escape.wasm"}),
    )
    .await;
    assert_eq!(parent_path.body["type"], "error");
    assert!(
        parent_path.body["reason"]
            .as_str()
            .unwrap()
            .contains("must not contain '..'")
    );
    host.stop().await;
 }
 #[tokio::test]
 async fn concurrent_spawns_of_one_id_leave_one_live_instance() {
    let world = create_world("concurrent-spawn");
    let wasm = toolbox_wasm().clone();
    let (host, mut mailbox) = start(&world).await;
    let source = passing_source(&world, "source");
    let ids = [
        spawn_request(&host, "spawn-race", &wasm, &source),
        spawn_request(&host, "spawn-race", &wasm, &source),
    ];
    let replies = receive_replies(&mut mailbox, &ids, Duration::from_secs(20)).await;
    let spawned = replies
        .iter()
        .filter(|r| r.body["type"] == "spawned")
        .count();
    let failed = replies.iter().filter(|r| r.body["type"] == "error").count();
    assert_eq!((spawned, failed), (1, 1));
    let echo = ask_type(
        &host,
        &mut mailbox,
        "spawn-race",
        json!({"type": "echo", "value": "live"}),
        "echo",
    )
    .await;
    assert_eq!(echo.body["value"], "live");
    tokio::time::sleep(Duration::from_millis(100)).await;
    let list = ask_type(
        &host,
        &mut mailbox,
        "spawn-race",
        json!({"type": "list", "path": "/data"}),
        "entries",
    )
    .await;
    let starts = list.body["names"]
        .as_array()
        .unwrap()
        .iter()
        .filter(|n| n.as_str().unwrap().starts_with("start-"))
        .count();
    assert_eq!(starts, 1);
    host.stop().await;
 }
 #[tokio::test]
 async fn stop_finishes_when_actor_stdin_is_full() {
    let world = create_world("full-stdin-stop");
    let wasm = toolbox_wasm().clone();
    let (host, mut mailbox) = start(&world).await;
    let source = passing_source(&world, "source");
    spawn_type(&host, &mut mailbox, "full-stdin", &wasm, &source).await;
    let ignore = json!({"type": "ignore-stdin"});
    ask_type(&host, &mut mailbox, "full-stdin", ignore, "ignoring").await;
    let large = json!({"type": "echo", "value": "x".repeat(256 * 1024)});
    host.broker
        .send("console", Some("full-stdin"), None, None, large);
    tokio::time::sleep(Duration::from_millis(100)).await;
    let stop = json!({"type": "stop", "actor": "full-stdin"});
    let id = host
        .broker
        .send("console", Some("broker"), None, None, stop);
    let stopped = tokio::time::timeout(
        Duration::from_secs(6),
        receive_reply(&mut mailbox, &id, Duration::from_secs(10)),
    )
    .await
    .expect("stop exceeded the five-second shutdown deadline");
    assert_eq!(stopped.body["type"], "stopped");
    host.stop().await;
 }
 #[tokio::test]
 async fn shutdown_reply_and_publish_survive_stop_and_upgrade() {
    let world = create_world("shutdown-output");
    let wasm = toolbox_wasm().clone();
    let (host, mut mailbox) = start(&world).await;
    let source = passing_source(&world, "source");
    spawn_type(&host, &mut mailbox, "shutdown-output", &wasm, &source).await;
    let subscribe = json!({"type": "subscribe", "actor": "shutdown-output"});
    ask_type(&host, &mut mailbox, "broker", subscribe, "subscribed").await;
    for operation in ["stop", "upgrade"] {
        let arm = json!({"type": "arm-shutdown"});
        ask_type(&host, &mut mailbox, "shutdown-output", arm, "armed").await;
        let body = match operation {
            "stop" => json!({"type": "stop", "actor": "shutdown-output"}),
            _ => {
                json!({"type": "upgrade", "actor": "shutdown-output", "wasm": wasm.display().to_string(), "source": source.display().to_string()})
            }
        };
        let id = host
            .broker
            .send("console", Some("broker"), None, None, body);
        receive_shutdown_messages(
            &mut mailbox,
            &id,
            if operation == "stop" {
                "stopped"
            } else {
                "upgraded"
            },
        )
        .await;
        if operation == "stop" {
            let start = json!({"type": "start", "actor": "shutdown-output"});
            ask_type(&host, &mut mailbox, "broker", start, "started").await;
        }
    }
    host.stop().await;
 }
 #[tokio::test]
 async fn candidates_receive_version_and_preexisting_spawn_state() {
    let world = create_world("candidate-context");
    let wasm = toolbox_wasm().clone();
    let (host, mut mailbox) = start(&world).await;
    let version_step =
        json!({"send": {"type": "version"}, "expect": {"type": "version", "version": "1"}});
    let version_source = source_with_test(&world, "version", json!({"steps": [version_step]}));
    let state_step = json!({"send": {"type": "read", "path": "/data/state.json"}, "expect": {"type": "content", "text": "seeded"}});
    let state_source = source_with_test(&world, "state", json!({"steps": [state_step]}));
    let state_dir = world.data_dir("stateful");
    std::fs::create_dir_all(&state_dir).unwrap();
    std::fs::write(state_dir.join("state.json"), "seeded").unwrap();
    let ids = [
        spawn_request(&host, "versioned", &wasm, &version_source),
        spawn_request(&host, "stateful", &wasm, &state_source),
    ];
    let replies = receive_replies(&mut mailbox, &ids, Duration::from_secs(20)).await;
    let successful = replies
        .iter()
        .filter(|reply| reply.body["type"] == "spawned")
        .count();
    assert_eq!(successful, 2);
    host.stop().await;
 }
 #[tokio::test]
 async fn running_actors_have_sockets_and_candidates_do_not() {
    // A TCP server on the host that answers each line with "echo: <line>".
    let listener = tokio::net::TcpListener::bind("127.0.0.1:0").await.unwrap();
    let address = listener.local_addr().unwrap().to_string();
    tokio::spawn(async move {
        while let Ok((stream, _)) = listener.accept().await {
            tokio::spawn(async move {
                use tokio::io::{AsyncBufReadExt, AsyncWriteExt};
                let (read, mut write) = stream.into_split();
                let mut lines = tokio::io::BufReader::new(read).lines();
                while let Ok(Some(line)) = lines.next_line().await {
                    let _ = write.write_all(format!("echo: {line}\n").as_bytes()).await;
                }
            });
        }
    });
    let world = create_world("sockets");
    let wasm = toolbox_wasm().clone();
    let (host, mut mailbox) = start(&world).await;
    let tcp = json!({"type": "tcp", "address": address, "text": "hi"});
    // The candidate test expects the connection to fail.
    let offline = source_with_test(&world, "offline", json!({"steps": [{"send": tcp, "expect": {"type": "error"}}]}));
    assert_eq!(spawn_actor(&host, &mut mailbox, "net", &wasm, &offline).await.body["type"], "spawned");
    let answer = ask(&host, &mut mailbox, "net", tcp).await;
    assert_eq!(answer.body, json!({"type": "tcp", "line": "echo: hi"}));
    host.stop().await;
 }
 /// Every message that arrives until the mailbox is quiet for `quiet`.
 async fn drain(mailbox: &mut mpsc::Receiver<Envelope>, quiet: Duration) -> Vec<Envelope> {
    let mut messages = Vec::new();
    while let Ok(Some(message)) = tokio::time::timeout(quiet, mailbox.recv()).await {
        messages.push(message);
    }
    messages
 }
 #[tokio::test]
 async fn tap_copies_every_routed_message_once() {
    let world = create_world("tap");
    let wasm = toolbox_wasm().clone();
    let (host, mut mailbox) = start(&world).await;
    let source = passing_source(&world, "source");
    spawn_type(&host, &mut mailbox, "tapped", &wasm, &source).await;
    let subscribe = json!({"type": "subscribe", "actor": "tapped"});
    assert_eq!(request(&host, &mut mailbox, subscribe).await.body["type"], "subscribed");
    assert_eq!(request(&host, &mut mailbox, json!({"type": "tap"})).await.body["type"], "tapping");
    let echo = json!({"type": "echo", "value": "hi"});
    let echo_id = host.broker.send("console", Some("tapped"), None, None, echo.clone());
    let publish = json!({"type": "publish", "value": "news"});
    host.broker.send("console", Some("tapped"), None, None, publish);
    let messages = drain(&mut mailbox, Duration::from_secs(2)).await;
    let copies: Vec<&Value> = messages
        .iter()
        .filter(|m| m.from == "broker" && m.body["type"] == "tapped")
        .map(|m| &m.body)
        .collect();
    // 4 copies (2 requests, 1 reply, 1 publish) + the reply + the publish itself.
    assert_eq!((copies.len(), messages.len()), (4, 6), "{messages:?}");
    for copy in &copies {
        assert!(copy["ts"].as_u64().unwrap() > 0, "{copy}");
    }
    let count = |want: Value| copies.iter().filter(|c| c["message"] == want).count();
    let request_copy = json!({"id": echo_id, "from": "console", "to": "tapped", "reply_to": null, "body": echo});
    assert_eq!(count(request_copy), 1, "{copies:?}");
    let reply_copies = copies
        .iter()
        .filter(|c| c["message"]["reply_to"] == echo_id.as_str() && c["message"]["from"] == "tapped" && c["message"]["to"] == "console")
        .count();
    assert_eq!(reply_copies, 1, "{copies:?}");
    let publish_copy = copies.iter().find(|c| c["message"]["body"]["type"] == "published").expect("publish not tapped");
    assert_eq!(publish_copy["message"]["from"], "tapped");
    assert_eq!(publish_copy["message"]["to"], Value::Null);
    assert_eq!(request(&host, &mut mailbox, json!({"type": "untap"})).await.body["type"], "untapped");
    let echo_id = host.broker.send("console", Some("tapped"), None, None, json!({"type": "echo", "value": "quiet"}));
    let messages = drain(&mut mailbox, Duration::from_secs(1)).await;
    assert_eq!(messages.len(), 1, "{messages:?}");
    assert_eq!(messages[0].reply_to.as_deref(), Some(echo_id.as_str()));
    host.stop().await;
 }
 #[tokio::test]
 async fn tap_survives_a_restart() {
    let world = create_world("tap-restart");
    let (host, mut mailbox) = start(&world).await;
    assert_eq!(request(&host, &mut mailbox, json!({"type": "tap"})).await.body["type"], "tapping");
    host.stop().await;
    assert!(world.read_meta("console").tapped);
    let (host, mut mailbox) = start(&world).await;
    let id = host.broker.send("console", Some("nobody"), None, None, json!({"type": "hello"}));
    let copy = tokio::time::timeout(Duration::from_secs(10), async {
        loop {
            let m = mailbox.recv().await.expect("console mailbox closed");
            if m.body["type"] == "tapped" && m.body["message"]["id"] == id.as_str() {
                return m;
            }
        }
    })
    .await
    .expect("no tapped copy after the restart");
    assert_eq!(copy.body["message"]["to"], "nobody");
    host.stop().await;
 }
 #[tokio::test]
 async fn a_full_tapper_mailbox_drops_copies_without_blocking() {
    let world = create_world("tap-full");
    let (host, mut mailbox) = start(&world).await;
    // "ghost" taps and never reads its mailbox.
    let mut ghost = host.mailbox("ghost");
    let mut sink = host.mailbox("sink");
    host.broker.send("ghost", Some("broker"), None, None, json!({"type": "tap"}));
    tokio::time::timeout(Duration::from_secs(10), async {
        while !world.read_meta("ghost").tapped {
            tokio::time::sleep(Duration::from_millis(10)).await;
        }
    })
    .await
    .expect("tap was not saved");
    let total = sausage::broker::MAILBOX_SIZE + 500;
    for n in 0..total {
        host.broker.send("console", Some("sink"), None, None, json!({"type": "n", "n": n}));
        assert_eq!(sink.try_recv().unwrap().body["n"], n);
    }
    assert!(mailbox.try_recv().is_err(), "a dropped copy reported something to the sender");
    let mut held = 0;
    while ghost.try_recv().is_ok() {
        held += 1;
    }
    assert_eq!(held, sausage::broker::MAILBOX_SIZE);
    host.broker.send("console", Some("sink"), None, None, json!({"type": "after"}));
    assert_eq!(ghost.try_recv().unwrap().body["type"], "tapped");
    host.stop().await;
 }
@@ -1,7 +0,0 @@
 [package]
 name = "bench"
 version = "0.1.0"
 edition = "2024"
 [dependencies]
 serde_json = "1"
@@ -1,45 +0,0 @@
 //! {"type":"bench","target":"echo","n":1000}: ping-pong with the target, one
 //! message at a time, and report the round-trip times.
 use serde_json::{Value, json};
 use std::io::{BufRead, Write};
 use std::time::Instant;
 fn main() {
    let mut out = std::io::stdout().lock();
    let mut lines = std::io::stdin().lock().lines();
    while let Some(Ok(line)) = lines.next() {
        let Ok(msg) = serde_json::from_str::<Value>(&line) else { continue };
        match msg["body"]["type"].as_str() {
            Some("shutdown") => break,
            Some("bench") => {
                let target = msg["body"]["target"].as_str().unwrap_or("echo").to_string();
                let n = msg["body"]["n"].as_u64().unwrap_or(1000);
                let mut times = Vec::new();
                let started = Instant::now();
                for i in 0..n {
                    let t = Instant::now();
                    writeln!(out, "{}", json!({"to": target, "id": i, "body": {"type": "ping", "i": i}})).unwrap();
                    out.flush().unwrap();
                    // Wait for the reply.
                    loop {
                        let Some(Ok(l)) = lines.next() else { return };
                        let Ok(r) = serde_json::from_str::<Value>(&l) else { continue };
                        if r["reply_to"].as_str().is_some_and(|s| s.ends_with(&format!("/{i}"))) {
                            break;
                        }
                    }
                    times.push(t.elapsed().as_micros() as u64);
                }
                let total = started.elapsed().as_secs_f64();
                times.sort();
                let p = |q: f64| times[((times.len() as f64 - 1.0) * q) as usize];
                let reply = json!({"type": "bench_result", "n": n, "total_s": total,
                    "msgs_per_s": (n as f64 / total).round(),
                    "p50_us": p(0.5), "p90_us": p(0.9), "p99_us": p(0.99), "max_us": p(1.0)});
                writeln!(out, "{}", json!({"to": msg["from"], "reply_to": msg["id"], "body": reply})).unwrap();
                out.flush().unwrap();
            }
            _ => {}
        }
    }
 }
@@ -1,6 +0,0 @@
 //! A bad version: it starts, waits 3 seconds (long enough for the smoke
 //! test), then panics. Used to test the automatic rollback.
 fn main() {
    std::thread::sleep(std::time::Duration::from_secs(3));
    panic!("this version is broken");
 }
@@ -1,15 +0,0 @@
 use serde_json::{json, Value};
 use std::io::{BufRead, Write};
 fn main() {
    let mut out = std::io::stdout().lock();
    for line in std::io::stdin().lock().lines() {
        let Ok(msg) = serde_json::from_str::<Value>(&line.unwrap()) else { continue };
        if msg["body"]["type"] == "shutdown" {
            break;
        }
        let env = json!({"to": msg["from"], "reply_to": msg["id"], "body": {"type": "echo", "got": msg["body"]}});
        writeln!(out, "{env}").unwrap();
        out.flush().unwrap();
    }
 }
@@ -1,8 +0,0 @@
 [package]
 name = "fetch"
 version = "0.1.0"
 edition = "2024"
 [dependencies]
 serde_json = "1"
 wstd = "0.6"
@@ -1,78 +0,0 @@
 //! Fetches URLs over HTTP(S) and writes the body to /public/fetch/<n>.
 //! Reads stdin and runs requests at the same time: while a fetch runs,
 //! `ping` still answers at once.
 use serde_json::{Value, json};
 use std::cell::RefCell;
 use std::rc::Rc;
 use wstd::http::{Body, Client, Request};
 use wstd::io::{AsyncRead, AsyncWrite};
 type Out = Rc<RefCell<Vec<String>>>;
 async fn flush(out: &Out) {
    let lines: Vec<String> = out.borrow_mut().drain(..).collect();
    let mut stdout = wstd::io::stdout();
    for l in lines {
        let _ = stdout.write_all(format!("{l}\n").as_bytes()).await;
    }
    let _ = stdout.flush().await;
 }
 async fn fetch(n: u64, msg: Value, out: Out) {
    let url = msg["body"]["url"].as_str().unwrap_or_default().to_string();
    let started = wstd::time::Instant::now();
    let result = async {
        let req = Request::get(&url).body(Body::empty()).map_err(|e| e.to_string())?;
        let resp = Client::new().send(req).await.map_err(|e| format!("{e:?}"))?;
        let status = resp.status().as_u16();
        let bytes = resp.into_body().contents().await.map_err(|e| format!("{e:?}"))?.to_vec();
        std::fs::create_dir_all("/public/fetch").map_err(|e| e.to_string())?;
        let path = format!("/public/fetch/{n}");
        std::fs::write(&path, &bytes).map_err(|e| e.to_string())?;
        Ok::<_, String>((status, bytes.len(), path))
    }
    .await;
    let ms = started.elapsed().as_millis();
    let body = match result {
        Ok((status, size, path)) => {
            let id = std::env::var("SAUSAGE_ACTOR").unwrap_or("fetch".into());
            json!({"type": "fetched", "status": status, "bytes": size, "path": path.replacen("/public", &format!("/actor/{id}/public"), 1), "ms": ms})
        }
        Err(e) => json!({"type": "error", "reason": e, "ms": ms}),
    };
    out.borrow_mut().push(json!({"to": msg["from"], "reply_to": msg["id"], "body": body}).to_string());
    flush(&out).await;
 }
 fn main() {
    wstd::runtime::block_on(async {
        let out: Out = Rc::new(RefCell::new(Vec::new()));
        let mut stdin = wstd::io::stdin();
        let mut buf = Vec::new();
        let mut chunk = vec![0u8; 8192];
        let mut n = 0u64;
        loop {
            let Ok(len) = stdin.read(&mut chunk).await else { break };
            if len == 0 {
                break;
            }
            buf.extend_from_slice(&chunk[..len]);
            while let Some(pos) = buf.iter().position(|b| *b == b'\n') {
                let line: Vec<u8> = buf.drain(..=pos).collect();
                let Ok(msg) = serde_json::from_slice::<Value>(&line) else { continue };
                match msg["body"]["type"].as_str() {
                    Some("shutdown") => return,
                    Some("fetch") => {
                        n += 1;
                        wstd::runtime::spawn(fetch(n, msg, out.clone())).detach();
                    }
                    Some("ping") => {
                        out.borrow_mut().push(json!({"to": msg["from"], "reply_to": msg["id"], "body": {"type": "pong"}}).to_string());
                        flush(&out).await;
                    }
                    _ => {}
                }
            }
        }
    });
 }
@@ -1,47 +0,0 @@
 //! Filesystem probe for the spike. Keeps files open across messages.
 use serde_json::{Value, json};
 use std::collections::HashMap;
 use std::io::{BufRead, Write};
 fn main() {
    let mut open: HashMap<String, std::fs::File> = HashMap::new();
    let mut out = std::io::stdout().lock();
    for line in std::io::stdin().lock().lines() {
        let Ok(line) = line else { break };
        let Ok(msg) = serde_json::from_str::<Value>(&line) else { continue };
        let b = &msg["body"];
        let path = b["path"].as_str().unwrap_or_default().to_string();
        let r = |res: std::io::Result<Value>| match res {
            Ok(v) => v,
            Err(e) => json!({"type": "error", "error": e.to_string()}),
        };
        let reply = match b["type"].as_str() {
            Some("shutdown") => break,
            Some("write") => r(std::fs::write(&path, b["text"].as_str().unwrap_or_default()).map(|_| json!({"type": "ok"}))),
            Some("open") => r((|| {
                let mut f = std::fs::File::create(&path)?;
                f.write_all(b["text"].as_str().unwrap_or_default().as_bytes())?;
                open.insert(path.clone(), f);
                Ok(json!({"type": "ok", "open": true}))
            })()),
            Some("append") => r((|| {
                let mut f = std::fs::OpenOptions::new().append(true).open(&path)?;
                f.write_all(b["text"].as_str().unwrap_or_default().as_bytes())?;
                open.insert(path.clone(), f);
                Ok(json!({"type": "ok", "open": true}))
            })()),
            Some("close") => json!({"type": "ok", "closed": open.remove(&path).is_some()}),
            Some("read") => r(std::fs::read_to_string(&path).map(|t| json!({"type": "content", "text": t}))),
            Some("list") => r(std::fs::read_dir(&path).map(|rd| {
                let mut names: Vec<String> = rd.filter_map(|e| e.ok()).map(|e| e.file_name().to_string_lossy().to_string()).collect();
                names.sort();
                json!({"type": "entries", "names": names})
            })),
            Some("remove") => r(std::fs::remove_file(&path).map(|_| json!({"type": "ok"}))),
            Some("crash") => panic!("asked to crash"),
            _ => json!({"type": "error", "error": "unknown message"}),
        };
        writeln!(out, "{}", json!({"to": msg["from"], "reply_to": msg["id"], "body": reply})).unwrap();
        out.flush().unwrap();
    }
 }
@@ -0,0 +1,115 @@
 # This file is automatically @generated by Cargo.
 # It is not intended for manual editing.
 version = 4
 [[package]]
 name = "itoa"
 version = "1.0.18"
 source = "registry+https://github.com/rust-lang/crates.io-index"
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 checksum = "cf8baf1c55e62ffcace7a9f06f4bd9cd3f0c4beb022d3b367256b91b87513d98"
 [[package]]
 name = "notes"
 version = "0.1.0"
 dependencies = [
 "sausage-actor",
 "serde_json",
 ]
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 checksum = "985e7ec9bb745e6ce6535b544d84d6cd6f7ad8bd711c398938ae983b91a766d9"
 dependencies = [
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 [[package]]
 name = "quote"
 version = "1.0.47"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "1fbf4db142a473a8d80c26bbf18454ed458bf8d26c8219c331daecfdbd079001"
 dependencies = [
 "proc-macro2",
 ]
 [[package]]
 name = "sausage-actor"
 version = "0.1.0"
 dependencies = [
 "serde",
 "serde_json",
 ]
 [[package]]
 name = "serde"
 version = "1.0.229"
 source = "registry+https://github.com/rust-lang/crates.io-index"
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 checksum = "e7e9cc8b1b85264074fbcc02a88680c4096b1e47df8f739dceb03bf482f04bd6"
 dependencies = [
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 name = "syn"
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 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "d78c8dee4c7bf0e14673097256fed6142ce9d3b85a408189d07482442145823b"
 dependencies = [
 "proc-macro2",
 "quote",
 "unicode-ident",
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 [[package]]
 name = "unicode-ident"
 version = "1.0.27"
 source = "registry+https://github.com/rust-lang/crates.io-index"
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 name = "zmij"
 version = "1.0.23"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "29666d0abbfad1e3dc4dcf6144730dd3a3ab225bbbdac83319345b1b44ccfc1b"
@@ -4,4 +4,7 @@ version = "0.1.0"
 edition = "2024"
 [dependencies]
 sausage-actor = { version = "0.1", path = "../../sdk" }
 serde_json = "1"
 [workspace]
@@ -1,7 +1,5 @@
-//! Keeps a list of notes in /data/notes.json and publishes them as
+//! Version 2 adds a note count and fixes the crash command.
-//! /public/notes.txt. Version 2: adds `count` and no longer crashes.
+use sausage_actor::{json, messages, reply};
 use serde_json::{Value, json};
 use std::io::{BufRead, Write};
 const DATA: &str = "/data/notes.json";
@@ -13,27 +11,21 @@ fn save(notes: &[String]) {
 fn main() {
    let mut notes: Vec<String> = std::fs::read_to_string(DATA)
        .ok()
-        .and_then(|s| serde_json::from_str(&s).ok())
+        .and_then(|text| serde_json::from_str(&text).ok())
        .unwrap_or_default();
-    let mut out = std::io::stdout().lock();
+    for message in messages() {
-    for line in std::io::stdin().lock().lines() {
+        let body = &message.body;
-        let Ok(line) = line else { break };
+        let response = match message.kind() {
-        let Ok(msg) = serde_json::from_str::<Value>(&line) else { continue };
+            "add" => {
        let body = &msg["body"];
        let reply = match body["type"].as_str() {
            Some("shutdown") => break,
            Some("add") => {
                notes.push(body["text"].as_str().unwrap_or_default().to_string());
                save(&notes);
                json!({"type": "added", "count": notes.len()})
            }
-            Some("list") => json!({"type": "notes", "items": notes}),
+            "list" => json!({"type": "notes", "items": notes}),
-            Some("count") => json!({"type": "count", "count": notes.len(), "version": 2}),
+            "count" => json!({"type": "count", "count": notes.len(), "version": 2}),
-            // Version 2 fixes the crash.
+            "crash" => json!({"type": "not_crashing", "version": 2}),
            Some("crash") => json!({"type": "not_crashing", "version": 2}),
            _ => json!({"type": "error", "reason": "unknown message"}),
        };
-        writeln!(out, "{}", json!({"to": msg["from"], "reply_to": msg["id"], "body": reply})).unwrap();
+        let _ = reply(&message, response);
        out.flush().unwrap();
    }
 }
@@ -0,0 +1,9 @@
 {
  "description": "version 2 counts notes and no longer crashes",
  "steps": [
    {"send": {"type": "add", "text": "test note"}, "expect": {"type": "added"}},
    {"send": {"type": "list"}, "expect": {"type": "notes"}},
    {"send": {"type": "count"}, "expect": {"type": "count", "version": 2}},
    {"send": {"type": "crash"}, "expect": {"type": "not_crashing"}}
  ]
 }
@@ -1,8 +0,0 @@
 {"send": {"type": "add", "text": "test note"}}
 {"expect": {"type": "added"}}
 {"send": {"type": "list"}}
 {"expect": {"type": "notes"}}
 {"send": {"type": "count"}}
 {"expect": {"type": "count", "version": 2}}
 {"send": {"type": "crash"}}
 {"expect": {"type": "not_crashing"}}
@@ -0,0 +1,115 @@
 # This file is automatically @generated by Cargo.
 # It is not intended for manual editing.
 version = 4
 [[package]]
 name = "itoa"
 version = "1.0.18"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "8f42a60cbdf9a97f5d2305f08a87dc4e09308d1276d28c869c684d7777685682"
 [[package]]
 name = "memchr"
 version = "2.8.3"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "cf8baf1c55e62ffcace7a9f06f4bd9cd3f0c4beb022d3b367256b91b87513d98"
 [[package]]
 name = "notes"
 version = "0.1.0"
 dependencies = [
 "sausage-actor",
 "serde_json",
 ]
 [[package]]
 name = "proc-macro2"
 version = "1.0.107"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "985e7ec9bb745e6ce6535b544d84d6cd6f7ad8bd711c398938ae983b91a766d9"
 dependencies = [
 "unicode-ident",
 ]
 [[package]]
 name = "quote"
 version = "1.0.47"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "1fbf4db142a473a8d80c26bbf18454ed458bf8d26c8219c331daecfdbd079001"
 dependencies = [
 "proc-macro2",
 ]
 [[package]]
 name = "sausage-actor"
 version = "0.1.0"
 dependencies = [
 "serde",
 "serde_json",
 ]
 [[package]]
 name = "serde"
 version = "1.0.229"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "4148590afebada386688f18773da617792bf2ef03ffc1e4cbd2b1d45b023e0ba"
 dependencies = [
 "serde_core",
 "serde_derive",
 ]
 [[package]]
 name = "serde_core"
 version = "1.0.229"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "67dca2c9c51e58a4791a4b1ed58308b39c64224d349a935ab5039aa360942a48"
 dependencies = [
 "serde_derive",
 ]
 [[package]]
 name = "serde_derive"
 version = "1.0.229"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "e7a5d71263a5a7d47b41f6b3f06ba276f10cc18b0931f1799f710578e2309348"
 dependencies = [
 "proc-macro2",
 "quote",
 "syn",
 ]
 [[package]]
 name = "serde_json"
 version = "1.0.154"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "e7e9cc8b1b85264074fbcc02a88680c4096b1e47df8f739dceb03bf482f04bd6"
 dependencies = [
 "itoa",
 "memchr",
 "serde",
 "serde_core",
 "zmij",
 ]
 [[package]]
 name = "syn"
 version = "3.0.9"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "d78c8dee4c7bf0e14673097256fed6142ce9d3b85a408189d07482442145823b"
 dependencies = [
 "proc-macro2",
 "quote",
 "unicode-ident",
 ]
 [[package]]
 name = "unicode-ident"
 version = "1.0.27"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "a2c754d6c33795a1c324727428e5a7dedb5b06195f9890bdbcba760d3e246563"
 [[package]]
 name = "zmij"
 version = "1.0.23"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "29666d0abbfad1e3dc4dcf6144730dd3a3ab225bbbdac83319345b1b44ccfc1b"
@@ -4,4 +4,7 @@ version = "0.1.0"
 edition = "2024"
 [dependencies]
 sausage-actor = { version = "0.1", path = "../../sdk" }
 serde_json = "1"
 [workspace]
@@ -1,7 +1,5 @@
-//! Keeps a list of notes in /data/notes.json and publishes them as
+//! Keep notes in `/data/notes.json` and publish them at `/public/notes.txt`.
-//! /public/notes.txt.
+use sausage_actor::{json, messages, reply};
 use serde_json::{Value, json};
 use std::io::{BufRead, Write};
 const DATA: &str = "/data/notes.json";
@@ -13,25 +11,20 @@ fn save(notes: &[String]) {
 fn main() {
    let mut notes: Vec<String> = std::fs::read_to_string(DATA)
        .ok()
-        .and_then(|s| serde_json::from_str(&s).ok())
+        .and_then(|text| serde_json::from_str(&text).ok())
        .unwrap_or_default();
-    let mut out = std::io::stdout().lock();
+    for message in messages() {
-    for line in std::io::stdin().lock().lines() {
+        let body = &message.body;
-        let Ok(line) = line else { break };
+        let response = match message.kind() {
-        let Ok(msg) = serde_json::from_str::<Value>(&line) else { continue };
+            "add" => {
        let body = &msg["body"];
        let reply = match body["type"].as_str() {
            Some("shutdown") => break,
            Some("add") => {
                notes.push(body["text"].as_str().unwrap_or_default().to_string());
                save(&notes);
                json!({"type": "added", "count": notes.len()})
            }
-            Some("list") => json!({"type": "notes", "items": notes}),
+            "list" => json!({"type": "notes", "items": notes}),
-            Some("crash") => panic!("asked to crash"),
+            "crash" => panic!("asked to crash"),
            _ => json!({"type": "error", "reason": "unknown message"}),
        };
-        writeln!(out, "{}", json!({"to": msg["from"], "reply_to": msg["id"], "body": reply})).unwrap();
+        let _ = reply(&message, response);
        out.flush().unwrap();
    }
 }
@@ -0,0 +1,7 @@
 {
  "description": "add a note, then list the notes",
  "steps": [
    {"send": {"type": "add", "text": "test note"}, "expect": {"type": "added"}},
    {"send": {"type": "list"}, "expect": {"type": "notes"}}
  ]
 }
@@ -1,4 +0,0 @@
 {"send": {"type": "add", "text": "test note"}}
 {"expect": {"type": "added"}}
 {"send": {"type": "list"}}
 {"expect": {"type": "notes"}}
@@ -1,7 +0,0 @@
 [package]
 name = "ticker"
 version = "0.1.0"
 edition = "2024"
 [dependencies]
 serde_json = "1"
@@ -1,16 +0,0 @@
 //! Sends {"type":"add","text":"tick N"} to `notes` every 50 ms, N = 1..=200.
 //! Does not read stdin, so the broker kills it at shutdown; that is fine.
 use std::io::Write;
 fn main() {
    let mut out = std::io::stdout().lock();
    for n in 1..=200 {
        let msg = serde_json::json!({"to": "notes", "body": {"type": "add", "text": format!("tick {n}")}});
        writeln!(out, "{msg}").unwrap();
        out.flush().unwrap();
        std::thread::sleep(std::time::Duration::from_millis(50));
    }
    // Stay alive without doing anything.
    loop {
        std::thread::sleep(std::time::Duration::from_secs(3600));
    }
 }
@@ -1,5 +1,23 @@
 {
  "nodes": {
    "flake-utils": {
      "inputs": {
        "systems": "systems"
      },
      "locked": {
        "lastModified": 1791914995,
        "narHash": "sha256-Zf/xfQEAasnwnmEfHqW/4hjDE/s44yn2hD4RuVIZRjA=",
        "owner": "numtide",
        "repo": "flake-utils",
        "rev": "b7a79d3fea1e214f6d668d521cecec0c01e26544",
        "type": "github"
      },
      "original": {
        "owner": "numtide",
        "repo": "flake-utils",
        "type": "github"
      }
    },
    "nixpkgs": {
      "locked": {
        "lastModified": 1791637130,
@@ -18,6 +36,7 @@
    },
    "root": {
      "inputs": {
        "flake-utils": "flake-utils",
        "nixpkgs": "nixpkgs",
        "rust-overlay": "rust-overlay"
      }
@@ -41,6 +60,21 @@
        "repo": "rust-overlay",
        "type": "github"
      }
    },
    "systems": {
      "locked": {
        "lastModified": 1681028828,
        "narHash": "sha256-Vy1rq5AaRuLzOxct8nz4T6wlgyUR7zLU309k9mBC768=",
        "owner": "nix-systems",
        "repo": "default",
        "rev": "da67096a3b9bf56a91d16901293e51ba5b49a27e",
        "type": "github"
      },
      "original": {
        "owner": "nix-systems",
        "repo": "default",
        "type": "github"
      }
    }
  },
  "root": "root",
@@ -1,26 +1,83 @@
 {
-  description = "Sausage: WASI actors with a message broker";
+  description = "Sausage: grow a system of WASI actors by talking to it";
  inputs = {
    nixpkgs.url = "github:NixOS/nixpkgs/nixpkgs-unstable";
    flake-utils.url = "github:numtide/flake-utils";
    rust-overlay.url = "github:oxalica/rust-overlay";
    rust-overlay.inputs.nixpkgs.follows = "nixpkgs";
  };
-  outputs = { nixpkgs, rust-overlay, ... }:
+  outputs = { nixpkgs, flake-utils, rust-overlay, ... }:
    flake-utils.lib.eachSystem flake-utils.lib.allSystems (system:
      let
-      system = "x86_64-linux";
+        pkgs = import nixpkgs {
-      pkgs = import nixpkgs { inherit system; overlays = [ rust-overlay.overlays.default ]; };
+          inherit system;
          overlays = [ rust-overlay.overlays.default ];
        };
        # The toolchain that builds the host and, at runtime, the actors.
        rust = pkgs.rust-bin.stable.latest.default.override {
          targets = [ "wasm32-wasip2" ];
          extensions = [ "rust-src" ];
        };
-    in {
+        rustPlatform = pkgs.makeRustPlatform { cargo = rust; rustc = rust; };
-      devShells.${system}.default = pkgs.mkShell {
+        sausage = rustPlatform.buildRustPackage {
-        packages = [ rust pkgs.wasmtime pkgs.wasm-tools pkgs.pkg-config pkgs.openssl ];
+          pname = "sausage";
          version = "0.1.0";
          src = ./.;
          cargoLock.lockFile = ./Cargo.lock;
          cargoBuildFlags = [ "-p" "sausage" ];
          doCheck = false;
          nativeBuildInputs = [ pkgs.makeWrapper ];
          # The `cargo` actor runs cargo at runtime. Build scripts need a C linker.
          postInstall = ''
            wrapProgram $out/bin/sausage --prefix PATH : ${pkgs.lib.makeBinPath [ rust pkgs.stdenv.cc ]}
          '';
          meta.mainProgram = "sausage";
        };
        # `nix run .#loop -- <world>` runs the newest `sausage run <world>`
        # from the public repo, again and again: after a crash or a broker
        # `exit` request it refreshes the flake and starts the host again,
        # so the world updates itself. `/quit` (exit code 0) ends the loop.
        # SAUSAGE_FLAKE overrides where it fetches from (any flake URL,
        # e.g. a fork or a local checkout).
        repoUrl = "git+https://gitea.surma.technology/surma/sausage";
        loop = pkgs.writeShellScriptBin "sausage-loop" ''
          url="''${SAUSAGE_FLAKE:-${repoUrl}}"
          if [ $# -eq 0 ]; then set -- world; fi
          while true; do
            nix run --refresh "$url#default" -- run "$@"
            code=$?
            if [ "$code" -eq 0 ]; then exit 0; fi
            echo "sausage-loop: sausage exited with $code, starting the newest version in 2 s …" >&2
            sleep 2
          done
        '';
      in
      {
        packages.default = sausage;
        # `nix flake check` runs every test of the host, the SDK, and the
        # agent. The tests build WASM actors with cargo, offline, from the
        # vendored crates of Cargo.lock.
        checks.tests = sausage.overrideAttrs (old: {
          pname = "sausage-tests";
          doCheck = true;
          cargoTestFlags = [ "-p" "sausage" "-p" "sausage-actor" "-p" "agent" ];
          preCheck = ''
            # Its own lock file pins crates that the vendored set may lack.
            rm -f cli/tests/actors/toolbox/Cargo.lock
          '';
        });
        apps.default = { type = "app"; program = "${sausage}/bin/sausage"; };
        apps.loop = { type = "app"; program = "${loop}/bin/sausage-loop"; };
        devShells.default = pkgs.mkShell {
          packages = [ rust pkgs.wasmtime pkgs.wasm-tools ];
          shellHook = ''
            export CARGO_HOME="$PWD/.cargo-home"
          '';
        };
-    };
+      });
 }
@@ -0,0 +1,15 @@
 [package]
 name = "sausage-actor"
 version = "0.1.0"
 edition = "2024"
 description = "SDK for Sausage actors."
 [features]
 default = []
 async = ["dep:async-channel", "dep:wstd"]
 [dependencies]
 async-channel = { version = "2", optional = true }
 serde = { version = "1", features = ["derive"] }
 serde_json = "1"
 wstd = { version = "0.6", optional = true }
@@ -0,0 +1,229 @@
 //! Small runtime helpers for Sausage actors.
 pub use serde_json::{Value, json};
 use serde::{Deserialize, Serialize};
 use std::io::BufRead;
 /// A message that an actor receives from the broker.
 #[derive(Clone, Debug, Deserialize, PartialEq, Serialize)]
 pub struct Message {
    /// The message ID.
    pub id: String,
    /// The ID of the sending actor.
    pub from: String,
    /// The ID of the message that this message answers.
    #[serde(skip_serializing_if = "Option::is_none")]
    pub reply_to: Option<String>,
    /// The message body.
    pub body: Value,
 }
 impl Message {
    /// Return the body's `type` string, or an empty string when it is missing.
    pub fn kind(&self) -> &str {
        self.body["type"].as_str().unwrap_or("")
    }
 }
 fn parse(line: &[u8]) -> Option<Message> {
    serde_json::from_slice::<Message>(line).ok()
 }
 fn is_shutdown(message: &Message) -> bool {
    message.from == "broker" && message.kind() == "shutdown"
 }
 /// Return this actor's ID from `SAUSAGE_ACTOR`, or an empty string if unset.
 pub fn me() -> String {
    std::env::var("SAUSAGE_ACTOR").unwrap_or_default()
 }
 /// Read messages from stdin until EOF or a shutdown message from the broker.
 ///
 /// Invalid JSON lines are skipped.
 pub fn messages() -> impl Iterator<Item = Message> {
    let stdin = std::io::stdin();
    let mut lines = stdin.lock().lines();
    std::iter::from_fn(move || {
        loop {
            let Ok(line) = lines.next()? else {
                continue;
            };
            let Some(message) = parse(line.as_bytes()) else {
                continue;
            };
            return (!is_shutdown(&message)).then_some(message);
        }
    })
 }
 /// Send a message to `to` and return its full ID (`<actor>/<own-id>`).
 pub fn send(to: &str, body: Value) -> String {
    let id = next_id();
    write_message(json!({"to": to, "id": id, "body": body}));
    format!("{}/{id}", me())
 }
 /// Reply to `message` and return the new message's full ID.
 pub fn reply(message: &Message, body: Value) -> String {
    let id = next_id();
    write_message(json!({
        "to": message.from,
        "id": id,
        "reply_to": message.id,
        "body": body,
    }));
    format!("{}/{id}", me())
 }
 /// Write a file so that readers see either the old or the new content,
 /// never half of it: write a temporary file next to `path`, then rename it.
 pub fn write_atomic(path: impl AsRef<std::path::Path>, contents: impl AsRef<[u8]>) -> std::io::Result<()> {
    let path = path.as_ref();
    let tmp = path.with_file_name(format!(".{}.tmp-{}", path.file_name().unwrap_or_default().to_string_lossy(), next_id()));
    std::fs::write(&tmp, contents)?;
    std::fs::rename(&tmp, path)
 }
 /// Publish a message to this actor's subscribers and return its full ID.
 pub fn publish(body: Value) -> String {
    let id = next_id();
    write_message(json!({"id": id, "body": body}));
    format!("{}/{id}", me())
 }
 fn write_message(message: Value) {
    use std::io::Write;
    let mut stdout = std::io::stdout().lock();
    writeln!(stdout, "{message}").unwrap();
    stdout.flush().unwrap();
 }
 fn next_id() -> String {
    use std::sync::OnceLock;
    use std::sync::atomic::{AtomicUsize, Ordering};
    use std::time::{SystemTime, UNIX_EPOCH};
    static START: OnceLock<u128> = OnceLock::new();
    static SEQUENCE: AtomicUsize = AtomicUsize::new(0);
    let start = START.get_or_init(|| {
        SystemTime::now()
            .duration_since(UNIX_EPOCH)
            .unwrap_or_default()
            .as_nanos()
    });
    format!("{start}-{}", SEQUENCE.fetch_add(1, Ordering::Relaxed))
 }
 /// An asynchronous inbox for actors that use HTTP or timers.
 #[cfg(feature = "async")]
 pub struct Inbox {
    rx: async_channel::Receiver<Message>,
    _reader: wstd::runtime::Task<()>,
 }
 #[cfg(feature = "async")]
 impl Inbox {
    /// Start the stdin reader inside the wstd runtime and return its inbox.
    /// The inbox owns the reader task and must be dropped to cancel it.
    pub fn start() -> Self {
        let (tx, rx) = async_channel::unbounded();
        let reader = wstd::runtime::spawn(read_messages(tx));
        Self { rx, _reader: reader }
    }
    /// Wait for the next message, or return `None` at EOF or shutdown.
    pub async fn recv(&self) -> Option<Message> {
        self.rx.recv().await.ok()
    }
    /// Return the next available message without waiting.
    pub fn try_recv(&self) -> Option<Message> {
        self.rx.try_recv().ok()
    }
    /// Return whether the reader closed the inbox, even when messages remain buffered.
    pub fn is_closed(&self) -> bool {
        self.rx.is_closed()
    }
 }
 #[cfg(feature = "async")]
 async fn read_messages(tx: async_channel::Sender<Message>) {
    use wstd::io::AsyncRead;
    let mut stdin = wstd::io::stdin();
    let mut buf = Vec::new();
    let mut chunk = [0; 8192];
    loop {
        let Ok(n) = stdin.read(&mut chunk).await else {
            break;
        };
        if n == 0 {
            break;
        }
        buf.extend_from_slice(&chunk[..n]);
        while let Some(pos) = buf.iter().position(|b| *b == b'\n') {
            let message = parse(&buf[..pos]);
            buf.drain(..=pos);
            let Some(message) = message else {
                continue;
            };
            if is_shutdown(&message) {
                tx.close();
                return;
            }
            if tx.send(message).await.is_err() {
                return;
            }
        }
    }
    tx.close();
 }
 #[cfg(test)]
 mod tests {
    use super::*;
    #[test]
    fn kind_reads_body_type() {
        let message: Message = serde_json::from_value(json!({
            "id": "broker/1",
            "from": "broker",
            "body": {"type": "ping"}
        }))
        .unwrap();
        assert_eq!(message.kind(), "ping");
        assert_eq!(message.reply_to, None);
    }
    #[test]
    fn kind_is_empty_when_type_is_missing() {
        let message: Message = serde_json::from_value(json!({
            "id": "broker/1",
            "from": "broker",
            "body": {}
        }))
        .unwrap();
        assert_eq!(message.kind(), "");
    }
    #[test]
    fn write_atomic_replaces_the_file() {
        let dir = std::env::temp_dir().join(format!("sausage-actor-{}", next_id()));
        std::fs::create_dir_all(&dir).unwrap();
        let path = dir.join("state.json");
        write_atomic(&path, "old").unwrap();
        write_atomic(&path, "new").unwrap();
        assert_eq!(std::fs::read_to_string(&path).unwrap(), "new");
        assert_eq!(std::fs::read_dir(&dir).unwrap().count(), 1);
        std::fs::remove_dir_all(dir).unwrap();
    }
    #[test]
    fn generated_ids_differ() {
        assert_ne!(next_id(), next_id());
    }
 }
Author	SHA1	Message	Date
Sausage Agent	0951ba18e1	README: run straight from the public URL (nix run git+https://...), clone optional ci / check (push) Successful in 8s Details	2026-10-16 20:55:39 +00:00
Sausage Agent	d0876626df	Public repo: .#loop fetches over public HTTPS, README for outsiders ci / check (push) Successful in 8s Details - flake.nix: .#loop runs git+https://gitea.surma.technology/surma/sausage (SAUSAGE_FLAKE overrides it); drop loop-internal / --internal (LAN SSH). - README: clone step, LLM token requirement, loop URL and SAUSAGE_FLAKE. - ci.yml: comment without internal host name.	2026-10-16 20:40:26 +00:00
Sausage Agent	c1f182d9b6	broker: remove op deletes an actor (on top of tap/untap) ci / check (push) Successful in 8s Details {"type":"remove","actor"} shuts the actor down normally, drops its mailbox, supervisor and actor.json entry (so also its subscriptions and tap), and deletes /actor/<id>/. Native actors cannot be removed. Re-applied from card-1-broker-remove (`3c91747`) onto card-2-broker-tap.	2026-10-16 11:48:50 +00:00
Sausage Agent	49453fa9af	broker: tap/untap = receive a copy of every routed message ci / check (push) Successful in 12m13s Details Tapped copies {type:tapped, message:{id,from,to,reply_to,body}, ts} are delivered directly (never tapped themselves), dropped when the tapper's mailbox is full, and the tap is saved in actor.json like subscriptions.	2026-10-16 11:14:09 +00:00
Sausage Agent	2ff30ecf70	Actor-served files: /actor/<id>/fs/ ci / check (push) Successful in 10s Details File operations under /actor/<id>/fs/ become messages from `fs` to <id> (fs_read, fs_write, fs_mkdir, fs_remove, fs_rename) with a 10 s timeout. vfs.rs wraps the wasi:filesystem implementation of wasmtime-wasi.	2026-10-16 01:25:11 +00:00
Sausage Agent	e1409b93f2	CI: `nix flake check` runs all tests; Gitea workflow ci / check (push) Successful in 8s Details - flake: checks.tests = the sausage package with doCheck (tests of sausage, sausage-actor, agent; fixtures build offline from vendored crates). - .gitea/workflows/ci.yml: `nix flake check -L` on runner label `nixos`. Not compiled: written by the Sausage agent.	2026-10-16 00:44:55 +00:00
Sausage Agent	3435b556fb	Broker `exit` request and `nix run .#loop` for self-updating hosts - broker: `{"type":"exit"}` answers `exiting`; `sausage run` then stops all actors and exits with code 75. - flake: apps `loop` / `loop-internal` run `nix run --refresh git+ssh://.../surma/sausage -- run <world>` in a loop; exit code 0 (/quit) ends the loop, anything else restarts. - PROTOCOL.md, README.md, test in cli/tests/host.rs. Not compiled: written by the Sausage agent, which cannot build the native host.	2026-10-16 00:37:25 +00:00
surma	567646ba87	Flake	2026-10-15 23:39:52 +01:00
surma	bcde6ba325	Plain POSIX files: remove commit on close (fs.rs) Staging every write until close broke tempfile, git, and SQLite, which expect normal files. Actors that need an atomic publish write a temporary file and rename it; the SDK has write_atomic for that.	2026-10-15 23:33:20 +01:00
surma	599ee510cb	fs: a rename of the open file itself no longer drops the staged write The pending commit moved to `to.join("")`, which has a trailing slash, so the commit rename failed and the staged file was deleted.	2026-10-15 23:12:03 +01:00
surma	285f77a9e2	Sockets: running actors get TCP, UDP, and DNS through wasi:sockets; candidates get no network	2026-10-15 19:27:45 +01:00
surma	c636eb0803	Agent: one turn path, tools and history in their own modules; SDK: one parser	2026-10-15 14:22:51 +01:00
surma	f9260faa5b	Host: one place for the instance config; message ids are strings	2026-10-15 13:44:06 +01:00
surma	11144b947e	Trim the harness to what it needs to keep going Host: - test first: a new version is tested where it lies; only an installed version goes to versions/, and instances run from there - data/ and public/ are shared by all versions; no snapshots; rollback restores code only - no re-delivery, status.json, list, remove/archive, smoke test, data/ hiding, or stdin timeout; rollback needs a version - supervisor.rs split out; one place for installing a version - init only writes the agent folder; run installs it like any actor - console: @actor, text to the agent, /help, /quit Agent: - every text goes out as a broadcast; 5-line prompt; 5 tools that describe themselves; turn.json only marks an active turn Docs: PROTOCOL.md, README.md, DECISIONS.md, AGENTS.md rewritten. Examples: only notes and notes-v2.	2026-10-15 13:35:45 +01:00
surma	cee862275c	Agent integration tests against a fake inference endpoint	2026-10-15 12:39:39 +01:00
surma	2c06f34931	Agent: drop the oldest turns when the context is too large; answer by ending the turn with text	2026-10-15 12:32:03 +01:00
surma	9d575b6a62	Host: fixes from the review, with regression tests - one live instance per actor: check after the lock; dropping an instance kills it - state snapshots keep target/ and .git/; only source copies skip them - one shutdown deadline; output during shutdown is still routed - deliveries route stdout meanwhile; a stuck stdin kills the instance (no partial lines) and the sender gets undeliverable; control requests are not blocked by a stuck delivery - Host::stop aborts running broker and cargo requests first - compile a version before installing it; roll back if it does not start - unique archive names; a failed archive keeps the actor manageable - commit on close: truncate without create; directory renames - candidates see SAUSAGE_VERSION and the existing state of a new actor - the host publishes PROTOCOL.md at /actor/broker/public/	2026-10-15 12:03:26 +01:00
surma	69cf80a114	Agent: durable turn and queue state, visible inbox closure, OpenAI phase; prompt fixes; fetch/bench fixes	2026-10-15 11:54:41 +01:00
surma	1cd8971aa3	Merge the world layout (folder is the source of truth)	2026-10-15 11:24:07 +01:00
surma	bfd9339d25	Integration tests for routing, filesystem, upgrades, rollback, cargo, and paths	2026-10-15 11:24:07 +01:00
surma	868b7aa3e4	AGENTS.md	2026-10-15 11:22:39 +01:00
surma	bb734a5c74	Merge main (SDK, agent) into wip-layout	2026-10-15 11:18:09 +01:00
surma	7f76eab161	SDK sausage-actor; examples and agent on the SDK; agent without limits - sausage-actor: Message, messages(), send/reply/publish, async Inbox - agent: append-only /data/history.jsonl, no caps on history, steps, waits, tool output, or reads; max_tokens only when configured (Anthropic: 32000)	2026-10-15 11:17:14 +01:00
surma	0a8e8c2e3c	World folder is the source of truth - actor/<id>/ holds actor.wasm, actor.json, source/, public/, data/, versions/ - the broker boots by scanning actor/; a changed actor.wasm is an upgrade, a rejected one stays in versions/ with a reason and the files come back - /actor hides every data/ folder - subscriptions live in the subscriber's actor.json - cargo installs the SDK and points sausage-actor at it; no build limits - PROTOCOL.md	2026-10-15 11:14:11 +01:00
surma	c9d9864743	Optimize dependencies in dev builds	2026-10-15 10:47:32 +01:00
surma	1f49d0f7bb	Sausage: host, broker, commit-on-close filesystem, cargo actor, console, agent Imported from the spike branch, with: - a library crate (Host API) for the CLI and the tests - JSON test scenarios for candidates - commit on close only for new or truncated files - a Nix flake: nix run -- init, nix run -- run	2026-10-15 10:45:23 +01:00