host: mount owner-written non-secret global config

Reviewed-on: #3

PROTOCOL.md

@@ -59,13 +59,15 @@ it exits. After 5 seconds, it kills the instance.
 
 ## Filesystem
 
-Each instance sees three folders:
+Each instance sees these mounts:
 
 | Path | Access | Contents |
 | --- | --- | --- |
 | `/data` | read-write by its actor; readable by every actor | the actor's state |
 | `/public` | read-write | the files that the actor publishes |
 | `/actor` | read-only | the `actor/` folder of the world |
+| `/config` | read-only | one non-secret global JSON file, owned by `shared` |
+| `/global` | read-write for `shared`, read-only for all other actors | backing directory containing that same `config` file |
 
 An actor can write only its own `/data`, but can read every actor's `/data` through `/actor/<id>/data/`. `/data` is not private: any unprotected secret file there is readable by every actor.
 
@@ -77,6 +79,28 @@ 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`).
 
+`/config` is global configuration, never credentials (in particular, never the
+LLM proxy token). The host initializes it to `{}` without reading or copying
+legacy actor settings. Configuration schema and typed edits belong to `shared`,
+not the host. Ordinary actors cannot write either `/config` or its alias
+`/global/config`: WASI mounts are read-only, with no message sender checks.
+
+WASI preopens directories rather than individual files. The host mounts the
+isolated world `global/` directory at `/` read-only and at `/global` with the
+owner's write access. `shared` publishes atomically by writing a sibling such
+as `/global/config.tmp`, closing it, then renaming it to `/global/config`.
+New opens of `/config` see the replacement, including in already-running
+actors; an already-open file retains its old inode. The root mount does not
+expose the rest of the host world. Candidate tests get a scratch copy of
+`global/`, so even `shared` tests cannot modify the live file.
+
+On disk, the one JSON file is `<world>/global/config`. `<world>/config` is a
+relative symlink to it, for native/world filesystem readers (including an
+export of the world directory). Host-side atomic writers must replace
+`<world>/global/config`, not replace the symlink. Starting an older world
+adds the empty file and alias without changing actor state; an existing
+regular `<world>/config` is moved into the backing directory on first use.
+
 Send large or binary data as a path under `/actor/<id>/public/`, not inside a
 message.
 
@@ -125,8 +149,8 @@ the request: the request's `type` in past tense (`spawned`, `upgraded`,
 | `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 |
+| `upgrade` | `actor`, `wasm`, `source`?, `built_by`? | test, then swap the version: a running actor is stopped (normal shutdown) and starts the new version; a stopped actor gets the new version and stays stopped, with its mailbox untouched, until `start`. The answer has `running` |
+| `rollback` | `actor`, `version` | go back to an older version; like `upgrade`, a stopped actor stays stopped. The answer has `running` |
 | `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 |
@@ -212,7 +236,8 @@ 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.
+it. A stopped actor is not started: it keeps its mailbox and runs the new
+version at the next `start`. 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

cli/src/broker.rs

@@ -255,6 +255,10 @@ impl Broker {
         }
         InstanceConfig {
             mounts: vec![
+                // WASI preopens directories, not files. This isolated directory
+                // supplies /config without exposing the rest of the world.
+                Mount { guest: "/".into(), host: scratch.map_or_else(|| self.world.global_dir(), |p| p.join("global")), writable: false },
+                Mount { guest: "/global".into(), host: scratch.map_or_else(|| self.world.global_dir(), |p| p.join("global")), writable: id == "shared" },
                 Mount { guest: "/actor".into(), host: self.world.actors_root(), writable: false },
                 Mount { guest: "/public".into(), host: own.join("public"), writable: true },
                 Mount { guest: "/data".into(), host: own.join("data"), writable: true },
@@ -331,12 +335,13 @@ impl Broker {
         Ok((component, tests))
     }
 
-    /// Make `version` the current `actor.wasm`, `source/`, and `actor.json`.
-    pub fn install(&self, id: &str, version: u64) -> Result<()> {
+    /// Make `version` the current `actor.wasm`, `source/`, and `actor.json`,
+    /// and record whether the actor runs.
+    pub fn install(&self, id: &str, version: u64, running: bool) -> Result<()> {
         self.world.install_files(id, version)?;
         self.update_meta(id, |m| {
             m.version = Some(version);
-            m.running = true;
+            m.running = running;
         })
     }
 
@@ -360,7 +365,7 @@ impl Broker {
 
     async fn create_version(self: &Arc<Self>, id: &str, meta: &VersionMeta, wasm: &Path, source: Option<&Path>) -> Result<Value> {
         let (_, tests) = self.try_version(id, meta, wasm, source).await?;
-        self.install(id, meta.version)?;
+        self.install(id, meta.version, true)?;
         self.start_supervisor(id, meta.version, true);
         Ok(json!({"type": "spawned", "actor": id, "version": meta.version, "tests": tests}))
     }

cli/src/candidate.rs

@@ -97,7 +97,7 @@ impl Candidate<'_> {
         let dir = self.broker.world.scratch_dir().join(format!("{}-{}-{n}", self.id, std::process::id()));
         let scratch = Scratch { dir: dir.clone() };
         let world = &self.broker.world;
-        for (from, name) in [(world.data_dir(self.id), "data"), (world.public_dir(self.id), "public")] {
+        for (from, name) in [(world.data_dir(self.id), "data"), (world.public_dir(self.id), "public"), (world.global_dir(), "global")] {
             std::fs::create_dir_all(dir.join(name))?;
             if from.is_dir() {
                 world::copy_tree(&from, &dir.join(name))?;

cli/src/lib.rs

@@ -48,6 +48,7 @@ impl Host {
         if lock.try_lock().is_err() {
             bail!("another sausage process runs {}", root.display());
         }
+        world.ensure_config()?;
         let broker = Broker::new(world.clone(), runtime::Runtime::new()?)?;
         world::write_atomic(&world.public_dir("broker").join("PROTOCOL.md"), PROTOCOL.as_bytes())?;
 

cli/src/runtime.rs

@@ -23,7 +23,9 @@ use wasmtime_wasi_http::{WasiHttpCtx, WasiHttpCtxView, WasiHttpHooks, WasiHttpVi
 use crate::broker::Broker;
 use crate::vfs::{Vfs, VfsState, VfsView};
 
-/// A host folder that the guest sees at `guest`.
+/// A host folder that the guest sees at `guest`. File-like root paths such
+/// as `/config` use an isolated backing directory mounted at `/`; owners
+/// get a separate writable directory alias for atomic replacement.
 #[derive(Clone, Debug)]
 pub struct Mount {
     pub guest: String,

cli/src/supervisor.rs

@@ -220,17 +220,16 @@ impl Supervisor {
 
     /// Make `version` current. It is compiled first (unless `component` is
     /// given): if that fails, nothing changes. `data/` and `public/` stay as
-    /// they are.
+    /// they are. A stopped actor stays stopped.
     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.broker.install(&self.id, version, self.running)?;
         self.version = version;
         self.component = Some(component);
-        self.running = true;
         self.restarts = 0;
         self.restart_at = None;
         Ok(())
@@ -239,20 +238,26 @@ impl Supervisor {
     async fn upgrade(&mut self, version: u64, component: Component, requester: String) -> Result<Value> {
         let previous = self.version;
         self.install(version, Some(component)).await?;
+        if !self.running {
+            // Installed, not started: main runs and mail is read at the next `start`.
+            return Ok(json!({"type": "upgraded", "actor": self.id, "version": version, "previous": previous, "running": false}));
+        }
         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}))
+        Ok(json!({"type": "upgraded", "actor": self.id, "version": version, "previous": previous, "running": true}))
     }
 
     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}))
+        if self.running {
+            self.start().await?;
+        }
+        Ok(json!({"type": "rolled_back", "actor": self.id, "from": from, "to": version, "running": self.running}))
     }
 
     /// Handle a control request. Returns `true` when the supervisor ends.

cli/src/vfs.rs

@@ -6,6 +6,8 @@
 //! actor `<id>` with a message from `fs` and waits up to `ASK_TIMEOUT` for
 //! the reply. Other paths go to `wasmtime-wasi` unchanged except that an
 //! actor directory listing advertises `fs/` when its source docs declare it.
+//! `/config` and `/global/config` are native mount paths: they deliberately
+//! use WASI mount permissions rather than actor-served write requests.
 //!
 //! - `fs_read {path}` -> `fs_file {text | base64}`, `fs_dir {entries: [{name, type}]}`
 //! - `fs_write {path, text | base64}`, `fs_mkdir {path}`, `fs_remove {path}`,

cli/src/world.rs

@@ -4,6 +4,8 @@
 //!
 //! ```text
 //! <world>/
+//!   global/config       non-secret global JSON (shared owns writes)
+//!   config -> global/config  world-facing read alias
 //!   actor/<id>/
 //!     actor.wasm        the current version
 //!     actor.json        version, running, subscriptions, tapped, watches (broker)
@@ -89,6 +91,37 @@ impl World {
         Self { root: root.into() }
     }
 
+    /// Isolated backing directory for the root /config mount and the
+    /// owner's writable /global alias. Never copy legacy actor config here.
+    pub fn global_dir(&self) -> PathBuf {
+        self.root.join("global")
+    }
+
+    pub fn config_path(&self) -> PathBuf {
+        self.global_dir().join("config")
+    }
+
+    /// Add the non-secret file to new and pre-existing worlds. The symlink
+    /// is for native world readers; actor mounts use the backing directory.
+    pub fn ensure_config(&self) -> Result<()> {
+        std::fs::create_dir_all(self.global_dir())?;
+        let alias = self.root.join("config");
+        if !self.config_path().exists() {
+            if alias.is_file() && !alias.is_symlink() {
+                std::fs::rename(&alias, self.config_path())?;
+            } else {
+                write_atomic(&self.config_path(), b"{}\n")?;
+            }
+        }
+        match std::fs::read_link(&alias) {
+            Ok(target) if target == Path::new("global/config") => {}
+            Ok(_) => bail!("{} must point to global/config", alias.display()),
+            Err(_) if alias.try_exists()? => bail!("{} already exists", alias.display()),
+            Err(_) => std::os::unix::fs::symlink("global/config", alias)?,
+        }
+        Ok(())
+    }
+
     pub fn actors_root(&self) -> PathBuf {
         self.root.join("actor")
     }
@@ -131,6 +164,7 @@ impl World {
         for id in NATIVE {
             world.ensure_actor_dirs(id)?;
         }
+        world.ensure_config()?;
         Ok(world)
     }
 
@@ -209,6 +243,9 @@ impl World {
         let prefixed = |prefix: &str| {
             path.strip_prefix(prefix).filter(|rest| rest.is_empty() || rest.starts_with('/'))
         };
+        if path == "/config" || path == "/global/config" {
+            return Ok(self.config_path());
+        }
         if let Some(rest) = prefixed("/actor") {
             return under(self.actors_root(), rest);
         }

cli/tests/host.rs

@@ -47,6 +47,83 @@ async fn receive_shutdown_messages(
     .expect("shutdown output or lifecycle reply did not arrive");
 }
 
+#[tokio::test]
+async fn global_config_is_readable_owner_written_and_atomically_replaced() {
+    let world = create_world("global-config");
+    let (host, mut mailbox) = start(&world).await;
+    let wasm = toolbox_wasm().clone();
+    for actor in ["shared", "reader"] {
+        let source = passing_source(&world, actor);
+        spawn_type(&host, &mut mailbox, actor, &wasm, &source).await;
+    }
+    let initial = ask_type(&host, &mut mailbox, "reader", json!({"type": "read", "path": "/config"}), "content").await;
+    assert_eq!(initial.body["text"], "{}\n");
+    for path in ["/config", "/global/config", "/global/config.tmp", "/actor/shared/data/../../../../global/config"] {
+        ask_type(&host, &mut mailbox, "reader", json!({"type": "write", "path": path, "text": "not allowed"}), "error").await;
+    }
+    ask_type(&host, &mut mailbox, "reader", json!({"type": "rename", "path": "/config", "to": "/global/stolen"}), "error").await;
+    // The root view stays read-only even for the owner; publication uses its
+    // writable directory alias, with a sibling temporary file and rename.
+    ask_type(&host, &mut mailbox, "shared", json!({"type": "write", "path": "/config", "text": "not allowed"}), "error").await;
+    let next = "{\"llm\":{\"thinking\":\"medium\"}}\n";
+    ask_type(&host, &mut mailbox, "shared", json!({"type": "write", "path": "/global/config.tmp", "text": next}), "ok").await;
+    let before = ask_type(&host, &mut mailbox, "reader", json!({"type": "read", "path": "/config"}), "content").await;
+    assert_eq!(before.body["text"], "{}\n");
+    // A native/world reader holding the old inode sees the complete old file.
+    let mut old = std::fs::File::open(world.root.join("config")).unwrap();
+    ask_type(&host, &mut mailbox, "shared", json!({"type": "rename", "path": "/global/config.tmp", "to": "/global/config"}), "ok").await;
+    let after = ask_type(&host, &mut mailbox, "reader", json!({"type": "read", "path": "/config"}), "content").await;
+    assert_eq!(after.body["text"], next);
+    assert_eq!(std::fs::read_to_string(world.root.join("config")).unwrap(), next);
+    assert_eq!(std::fs::read_to_string(world.resolve("reader", "/config").unwrap()).unwrap(), next);
+    let mut previous = String::new();
+    std::io::Read::read_to_string(&mut old, &mut previous).unwrap();
+    assert_eq!(previous, "{}\n");
+    assert!(!world.global_dir().join("config.tmp").exists());
+    // The mount must not give shared writable access to any other world data.
+    ask_type(&host, &mut mailbox, "shared", json!({"type": "write", "path": "/global/../actor/reader/data/escape", "text": "no"}), "error").await;
+    host.stop().await;
+    let (host, mut mailbox) = start(&world).await;
+    let persisted = ask_type(&host, &mut mailbox, "reader", json!({"type": "read", "path": "/config"}), "content").await;
+    assert_eq!(persisted.body["text"], next);
+    host.stop().await;
+}
+
+#[tokio::test]
+async fn global_config_candidates_cannot_change_the_live_file() {
+    let world = create_world("candidate-global-config");
+    let (host, mut mailbox) = start(&world).await;
+    let source = source_with_test(&world, "shared", json!({"steps": [
+        {"send": {"type": "write", "path": "/global/next", "text": "{\"test\":true}"}, "expect": {"type": "ok"}},
+        {"send": {"type": "rename", "path": "/global/next", "to": "/global/config"}, "expect": {"type": "ok"}},
+        {"send": {"type": "read", "path": "/config"}, "expect": {"type": "content", "text": "{\"test\":true}"}}
+    ]}));
+    spawn_type(&host, &mut mailbox, "shared", toolbox_wasm(), &source).await;
+    assert_eq!(std::fs::read_to_string(world.config_path()).unwrap(), "{}\n");
+    host.stop().await;
+}
+
+#[tokio::test]
+async fn global_config_is_added_to_existing_worlds_without_copying_actor_settings() {
+    let world = create_world("old-world-config");
+    std::fs::remove_file(world.root.join("config")).unwrap();
+    std::fs::remove_dir_all(world.global_dir()).unwrap();
+    world.ensure_actor_dirs("shared").unwrap();
+    // Synthetic marker only; no actual credentials are read in this test.
+    std::fs::write(world.data_dir("shared").join("config.json"), "legacy-private-marker").unwrap();
+    let (host, _) = start(&world).await;
+    assert_eq!(std::fs::read_to_string(world.root.join("config")).unwrap(), "{}\n");
+    assert_eq!(std::fs::read_to_string(world.data_dir("shared").join("config.json")).unwrap(), "legacy-private-marker");
+    host.stop().await;
+    // Preserve an operator-provided global config when adding the mounts.
+    std::fs::remove_file(world.root.join("config")).unwrap();
+    std::fs::remove_dir_all(world.global_dir()).unwrap();
+    std::fs::write(world.root.join("config"), "{\"operator\":true}").unwrap();
+    let (host, _) = start(&world).await;
+    assert_eq!(std::fs::read_to_string(world.root.join("config")).unwrap(), "{\"operator\":true}");
+    host.stop().await;
+}
+
 #[tokio::test]
 async fn routes_replies_publishes_and_reports_undeliverable() {
     let world = create_world("routing");
@@ -506,6 +583,50 @@ async fn rolls_back_a_crash_loop_to_the_previous_version_without_restoring_data(
     host.stop().await;
 }
 
+#[tokio::test]
+async fn upgrade_and_rollback_keep_a_stopped_actor_stopped() {
+    let world = create_world("upgrade-stopped");
+    let wasm = toolbox_wasm().clone();
+    let (host, mut mailbox) = start(&world).await;
+    let source = passing_source(&world, "source");
+    spawn_type(&host, &mut mailbox, "sleeper", &wasm, &source).await;
+    let stopped = request(&host, &mut mailbox, json!({"type": "stop", "actor": "sleeper"})).await;
+    assert_eq!(stopped.body["type"], "stopped");
+
+    let upgraded = upgrade_actor(&host, &mut mailbox, "sleeper", &wasm, &source).await;
+    assert_eq!(upgraded.body["type"], "upgraded", "{upgraded:?}");
+    assert_eq!(upgraded.body["version"], 2);
+    assert_eq!(upgraded.body["running"], false);
+    let meta = world.read_meta("sleeper");
+    assert_eq!((meta.version, meta.running), (Some(2), false));
+
+    // Mail waits in the mailbox: the stopped actor reads nothing.
+    let waiting = host.broker.send("console", Some("sleeper"), None, None, json!({"type": "version"}));
+    assert!(
+        tokio::time::timeout(Duration::from_millis(500), receive_reply(&mut mailbox, &waiting, Duration::from_secs(10)))
+            .await
+            .is_err(),
+        "a stopped actor must not answer"
+    );
+
+    let rolled_back = request(&host, &mut mailbox, json!({"type": "rollback", "actor": "sleeper", "version": 1})).await;
+    assert_eq!(rolled_back.body["type"], "rolled_back", "{rolled_back:?}");
+    assert_eq!(rolled_back.body["running"], false);
+    assert!(!world.read_meta("sleeper").running);
+
+    // `start` runs the installed version and delivers the waiting message.
+    let started = request(&host, &mut mailbox, json!({"type": "start", "actor": "sleeper"})).await;
+    assert_eq!(started.body["type"], "started");
+    let answer = receive_reply(&mut mailbox, &waiting, Duration::from_secs(10)).await;
+    assert_eq!(answer.body["version"], "1");
+
+    // A running actor still restarts on the new version.
+    let running = upgrade_actor(&host, &mut mailbox, "sleeper", &wasm, &source).await;
+    assert_eq!(running.body["running"], true);
+    assert_eq!(ask(&host, &mut mailbox, "sleeper", json!({"type": "version"})).await.body["version"], "3");
+    host.stop().await;
+}
+
 #[tokio::test]
 async fn explicit_rollback_keeps_current_data() {
     let world = create_world("explicit-rollback");