host: sausage run with the userland bundle, real shell and services (T13)

- userland/bundle.nu builds the userland and assembles target/userland/bin
  (bin names, tools.txt aliases, brush as sh and bash).
- run and sh take --userland (default SAUSAGE_USERLAND); /bin is read-only.
- The console's bash tool runs through the process table with the
  conversation id; large output spills to the world's /tmp.
- sausage run starts the services supervisor.

P1 exit session (openai/gpt-6.1-sol, fresh world): write, read, edit, git
init/add/commit/diff/log, grep -rn, rg, find and a sed|sort|uniq|wc pipeline.

host/js/bundle.js

@@ -44318,7 +44318,7 @@ var path2 = (cwd, input) => {
   }
   return "/" + parts.join("/");
 };
-function environment(cwd = "/") {
+function environment(cwd = "/", conversation) {
   const call = (kind, p, bytes2 = []) => ops.op_file(kind, path2(cwd, p), bytes2);
   const env = {
     id: "world",
@@ -44355,7 +44355,7 @@ function environment(cwd = "/") {
         const exists = await call("stat", current);
         if (!exists.ok) {
           const r = await call("mkdir", current);
-          if (!r.ok) return r;
+          if (!r.ok && (await call("stat", current)).value?.kind !== "directory") return r;
         }
       }
       return ok(void 0);
@@ -44377,8 +44377,27 @@ function environment(cwd = "/") {
       });
     },
     exec: async (command, options, context) => {
+      let spillPath;
+      let pending = "", bytes2 = 0, lines2 = 0;
+      const output = async (text2, stream2) => {
+        options?.onOutput?.(text2, context, { stream: stream2 });
+        if (!options?.spill) return;
+        bytes2 += new TextEncoder().encode(text2).length;
+        lines2 += text2.split("\n").length - 1;
+        if (!spillPath) {
+          pending += text2;
+          if (bytes2 <= options.spill.afterBytes && lines2 + (pending.endsWith("\n") ? 0 : 1) <= options.spill.afterLines) return;
+          spillPath = `/tmp/bash-${crypto.randomUUID()}.log`;
+          const created = await env.writeFile(spillPath, pending);
+          if (!created.ok) throw new Error(created.error.message);
+          pending = "";
+        } else {
+          const appended = await call("append", spillPath, Array.from(new TextEncoder().encode(text2)));
+          if (!appended.ok) throw new Error(appended.error.message);
+        }
+      };
       try {
-        const rid = ops.op_exec(command, options?.cwd ?? cwd, options?.timeout);
+        const rid = ops.op_exec(command, options?.cwd ?? cwd, options?.timeout, conversation);
         const decoders = { stdout: new TextDecoder(), stderr: new TextDecoder() };
         let result;
         while (true) {
@@ -44387,16 +44406,16 @@ function environment(cwd = "/") {
             result = chunk;
             break;
           }
-          options?.onOutput?.(decoders[chunk.stream].decode(new Uint8Array(chunk.bytes), { stream: true }), context, { stream: chunk.stream });
+          await output(decoders[chunk.stream].decode(new Uint8Array(chunk.bytes), { stream: true }), chunk.stream);
         }
         if (result.error) throw new Error(result.error);
         for (const stream2 of ["stdout", "stderr"]) {
           const text2 = decoders[stream2].decode();
-          if (text2) options?.onOutput?.(text2, context, { stream: stream2 });
+          if (text2) await output(text2, stream2);
         }
-        return ok({ exitCode: result.exitCode });
+        return ok({ exitCode: result.exitCode, ...spillPath ? { spillPath } : {} });
       } catch (error) {
-        return { ok: false, error };
+        return { ok: false, error: Object.assign(new Error(String(error)), { code: "unknown", ...spillPath ? { spillPath } : {} }) };
       }
     },
     cleanup: async () => {
@@ -44442,7 +44461,7 @@ registry.install(CodingTools);
 var harness = await Harness.open(await openStorage(globalThis.storagePath), {
   models,
   registry,
-  env: (target) => environment(target.cwd ?? "/")
+  env: (target) => environment(target.cwd ?? "/", target.conversationId)
 }, BACKGROUND_CONTEXT);
 var root = await harness.root(BACKGROUND_CONTEXT, { agent: { model: { provider: "openai", modelId: model2.id }, thinkingLevel: "low", cwd: "/", extensions: [CodingTools] } });
 var watch = await root.watch(BACKGROUND_CONTEXT);