fix(core): retain interrupted shell output

packages/core/src/shell.ts

@@ -35,6 +35,7 @@ type Active = {
   done: Deferred.Deferred<Info, NotFoundError>
   timeoutFiber?: Fiber.Fiber<void>
   timeout?: (duration: number) => Effect.Effect<void>
+  kill?: () => Effect.Effect<void>
 }
 
 /**
@@ -59,6 +60,8 @@ export interface Interface {
   readonly wait: (id: Shell.ID) => Effect.Effect<Shell.Info, NotFoundError>
   // Replaces the running command's timeout from now; zero clears it.
   readonly timeout: (id: Shell.ID, duration: number) => Effect.Effect<Shell.Info, NotFoundError>
+  // Stops a running command while retaining its terminal state and output.
+  readonly kill: (id: Shell.ID) => Effect.Effect<Shell.Info, NotFoundError>
   readonly output: (id: Shell.ID, input?: Shell.OutputInput) => Effect.Effect<Shell.Output, NotFoundError>
   readonly remove: (id: Shell.ID) => Effect.Effect<void, NotFoundError>
 }
@@ -120,6 +123,12 @@ export const layer = (options?: ShellSelect.Options) => Layer.effect(
       yield* removeSession(id)
     })
 
+    const kill = Effect.fn("Shell.kill")(function* (id: Shell.ID) {
+      const session = yield* require(id)
+      if (session.kill) yield* session.kill()
+      return yield* Deferred.await(session.done)
+    })
+
     const list = Effect.fn("Shell.list")(function* () {
       return Array.from(sessions.values())
         .filter((session) => session.info.status === "running")
@@ -313,6 +322,8 @@ export const layer = (options?: ShellSelect.Options) => Layer.effect(
                 )
               })
 
+            session.kill = () => finish("exited", undefined, handle.kill().pipe(Effect.catch(() => Effect.void)))
+
             yield* session.timeout(invocation.timeout)
 
             runFork(
@@ -335,7 +346,7 @@ export const layer = (options?: ShellSelect.Options) => Layer.effect(
       return session.info
     })
 
-    return Service.of({ name, create, list, get, wait, timeout, output, remove })
+    return Service.of({ name, create, list, get, wait, timeout, kill, output, remove })
   }),
 )
 

packages/core/src/tool/plugin/shell.ts

@@ -224,7 +224,7 @@ export const Plugin = {
                 const run = settleShell().pipe(
                   Effect.tap((output) => Deferred.succeed(settled, output)),
                   Effect.map((output) => output.output),
-                  Effect.onInterrupt(() => shell.remove(info.id).pipe(Effect.ignore)),
+                  Effect.onInterrupt(() => shell.kill(info.id).pipe(Effect.ignore)),
                 )
                 const job = yield* runtime.job.start({
                   id: context.callID,

packages/core/test/tool-shell.test.ts

@@ -480,6 +480,44 @@ describe("ShellTool", () => {
     ),
   )
 
+  it.live("retains partial output when a foreground command is interrupted", () =>
+    Effect.acquireUseRelease(
+      Effect.promise(() => tmpdir()),
+      (tmp) => {
+        reset()
+        return withSession(tmp.path, (registry) =>
+          Effect.gen(function* () {
+            const jobs = yield* Job.Service
+            const shell = yield* Shell.Service
+            const scope = yield* Scope.Scope
+            const waiting = yield* executeTool(
+              registry,
+              call({ command: steadyProgressCommand }, "call-interrupt-output"),
+            ).pipe(Effect.forkIn(scope, { startImmediately: true }))
+
+            const waitForShell = (remaining = 1000): Effect.Effect<ShellSchema.ID, Error> =>
+              Effect.gen(function* () {
+                const job = yield* jobs.get("call-interrupt-output")
+                const shellID = job?.metadata?.shellID
+                if (typeof shellID === "string") return ShellSchema.ID.make(shellID)
+                if (remaining <= 0) return yield* Effect.fail(new Error("Timed out waiting for foreground shell"))
+                yield* Effect.promise(() => Bun.sleep(1))
+                return yield* waitForShell(remaining - 1)
+              })
+            const id = yield* waitForShell()
+            yield* Effect.sleep(Duration.millis(100))
+            yield* Fiber.interrupt(waiting)
+
+            expect((yield* shell.get(id)).status).toBe("exited")
+            expect((yield* shell.output(id)).output).toContain("steady")
+            yield* shell.remove(id)
+          }),
+        )
+      },
+      (tmp) => Effect.promise(() => tmp[Symbol.asyncDispose]().then(() => undefined)),
+    ),
+  )
+
   it.live("returns the shell id for a background command", () =>
     Effect.acquireUseRelease(
       Effect.promise(() => tmpdir()),