fix(task): preserve subtask cancellation during startup

Keep prompt reads, subtask execution, and shell runner wiring on shared Effect services so prompt no longer carries its own abort-signal adapters or duplicate task flow.

packages/opencode/src/effect/runner.ts

@@ -1,10 +1,10 @@
-import { Cause, Deferred, Effect, Exit, Fiber, Option, Schema, Scope, SynchronizedRef } from "effect"
+import { Cause, Deferred, Effect, Exit, Fiber, Schema, Scope, SynchronizedRef } from "effect"
 
 export interface Runner<A, E = never> {
   readonly state: Runner.State<A, E>
   readonly busy: boolean
   readonly ensureRunning: (work: Effect.Effect<A, E>) => Effect.Effect<A, E>
-  readonly startShell: (work: (signal: AbortSignal) => Effect.Effect<A, E>) => Effect.Effect<A, E>
+  readonly startShell: (work: Effect.Effect<A, E>) => Effect.Effect<A, E>
   readonly cancel: Effect.Effect<void>
 }
 
@@ -20,7 +20,6 @@ export namespace Runner {
   interface ShellHandle<A, E> {
     id: number
     fiber: Fiber.Fiber<A, E>
-    abort: AbortController
   }
 
   interface PendingHandle<A, E> {
@@ -102,9 +101,7 @@ export namespace Runner {
 
     const stopShell = (shell: ShellHandle<A, E>) =>
       Effect.gen(function* () {
-        shell.abort.abort()
+        yield* Fiber.interrupt(shell.fiber)
-        const exit = yield* Fiber.await(shell.fiber).pipe(Effect.timeoutOption("100 millis"))
-        if (Option.isNone(exit)) yield* Fiber.interrupt(shell.fiber)
         yield* Fiber.await(shell.fiber).pipe(Effect.exit, Effect.asVoid)
       })
 
@@ -138,7 +135,7 @@ export namespace Runner {
         ),
       )
 
-    const startShell = (work: (signal: AbortSignal) => Effect.Effect<A, E>) =>
+    const startShell = (work: Effect.Effect<A, E>) =>
       SynchronizedRef.modifyEffect(
         ref,
         Effect.fnUntraced(function* (st) {
@@ -153,9 +150,8 @@ export namespace Runner {
           }
           yield* busy
           const id = next()
-          const abort = new AbortController()
+          const fiber = yield* work.pipe(Effect.ensuring(finishShell(id)), Effect.forkChild)
-          const fiber = yield* work(abort.signal).pipe(Effect.ensuring(finishShell(id)), Effect.forkChild)
+          const shell = { id, fiber } satisfies ShellHandle<A, E>
-          const shell = { id, fiber, abort } satisfies ShellHandle<A, E>
           return [
             Effect.gen(function* () {
               const exit = yield* Fiber.await(fiber)

packages/opencode/src/session/prompt.ts

@@ -24,7 +24,6 @@ import { ToolRegistry } from "../tool/registry"
 import { Runner } from "@/effect/runner"
 import { MCP } from "../mcp"
 import { LSP } from "../lsp"
-import { ReadTool } from "../tool/read"
 import { FileTime } from "../file/time"
 import { Flag } from "../flag/flag"
 import { ulid } from "ulid"
@@ -33,11 +32,11 @@ import * as CrossSpawnSpawner from "@/effect/cross-spawn-spawner"
 import * as Stream from "effect/Stream"
 import { Command } from "../command"
 import { pathToFileURL, fileURLToPath } from "url"
+import { Config } from "../config/config"
 import { ConfigMarkdown } from "../config/markdown"
 import { SessionSummary } from "./summary"
 import { NamedError } from "@opencode-ai/util/error"
 import { SessionProcessor } from "./processor"
-import { TaskTool } from "@/tool/task"
 import { Tool } from "@/tool/tool"
 import { Permission } from "@/permission"
 import { SessionStatus } from "./status"
@@ -47,6 +46,8 @@ import { AppFileSystem } from "@/filesystem"
 import { Truncate } from "@/tool/truncate"
 import { decodeDataUrl } from "@/util/data-url"
 import { Process } from "@/util/process"
+import { run as read } from "@/tool/read"
+import { output as subtaskOutput, run as subtask } from "@/tool/subtask"
 import { Cause, Effect, Exit, Layer, Option, Scope, ServiceMap } from "effect"
 import { InstanceState } from "@/effect/instance-state"
 import { makeRuntime } from "@/effect/run-service"
@@ -101,6 +102,7 @@ export namespace SessionPrompt {
       const spawner = yield* ChildProcessSpawner.ChildProcessSpawner
       const scope = yield* Scope.Scope
       const instruction = yield* Instruction.Service
+      const llm = yield* LLM.Service
 
       const state = yield* InstanceState.make(
         Effect.fn("SessionPrompt.state")(function* () {
@@ -218,26 +220,29 @@ export namespace SessionPrompt {
         const msgs = onlySubtasks
           ? [{ role: "user" as const, content: subtasks.map((p) => p.prompt).join("\n") }]
           : yield* MessageV2.toModelMessagesEffect(context, mdl)
-        const text = yield* Effect.promise(async (signal) => {
+        const text = yield* llm
-          const result = await LLM.stream({
+          .stream({
             agent: ag,
             user: firstInfo,
             system: [],
             small: true,
             tools: {},
             model: mdl,
-            abort: signal,
             sessionID: input.session.id,
             retries: 2,
             messages: [{ role: "user", content: "Generate a title for this conversation:\n" }, ...msgs],
           })
-          return result.text
+          .pipe(
-        })
+            Stream.runFold(
+              () => "",
+              (text: string, event: LLM.Event) => (event.type === "text-delta" ? text + event.text : text),
+            ),
+          )
         const cleaned = text
           .replace(/<think>[\s\S]*?<\/think>\s*/g, "")
           .split("\n")
-          .map((line) => line.trim())
+          .map((line: string) => line.trim())
-          .find((line) => line.length > 0)
+          .find((line: string) => line.length > 0)
         if (!cleaned) return
         const t = cleaned.length > 100 ? cleaned.substring(0, 97) + "..." : cleaned
         yield* sessions
@@ -397,11 +402,12 @@ NOTE: At any point in time through this workflow you should feel free to ask the
         using _ = log.time("resolveTools")
         const tools: Record<string, AITool> = {}
 
-        const context = (args: any, options: ToolExecutionOptions): Tool.Context => ({
+        const context = (args: any, options: ToolExecutionOptions): Tool.Context =>
-          sessionID: input.session.id,
+          Tool.context({
-          abort: options.abortSignal!,
+            abort: options.abortSignal,
-          messageID: input.processor.message.id,
             callID: options.toolCallId,
+            sessionID: input.session.id,
+            messageID: input.processor.message.id,
             extra: { model: input.model, bypassAgentCheck: input.bypassAgentCheck },
             agent: input.agent.name,
             messages: input.messages,
@@ -555,13 +561,20 @@ NOTE: At any point in time through this workflow you should feel free to ask the
         model: Provider.Model
         lastUser: MessageV2.User
         sessionID: SessionID
-        session: Session.Info
-        msgs: MessageV2.WithParts[]
       }) {
-        const { task, model, lastUser, sessionID, session, msgs } = input
+        const { task, model, lastUser, sessionID } = input
         const ctx = yield* InstanceState.context
-        const taskTool = yield* Effect.promise(() => registry.named.task.init())
+        const taskAgent = yield* agents.get(task.agent)
+        if (!taskAgent) {
+          const available = (yield* agents.list()).filter((a) => !a.hidden).map((a) => a.name)
+          const hint = available.length ? ` Available agents: ${available.join(", ")}` : ""
+          const error = new NamedError.Unknown({ message: `Agent not found: "${task.agent}".${hint}` })
+          yield* bus.publish(Session.Event.Error, { sessionID, error: error.toObject() })
+          throw error
+        }
+
         const taskModel = task.model ? yield* getModel(task.model.providerID, task.model.modelID, sessionID) : model
+        const taskRef = { providerID: taskModel.providerID, modelID: taskModel.id }
         const assistantMessage: MessageV2.Assistant = yield* sessions.updateMessage({
           id: MessageID.ascending(),
           role: "assistant",
@@ -601,57 +614,71 @@ NOTE: At any point in time through this workflow you should feel free to ask the
           subagent_type: task.agent,
           command: task.command,
         }
-        yield* plugin.trigger("tool.execute.before", { tool: "task", sessionID, callID: part.id }, { args: taskArgs })
+        yield* plugin.trigger(
-
+          "tool.execute.before",
-        const taskAgent = yield* agents.get(task.agent)
+          { tool: "task", sessionID, callID: part.callID },
-        if (!taskAgent) {
+          { args: taskArgs },
-          const available = (yield* agents.list()).filter((a) => !a.hidden).map((a) => a.name)
+        )
-          const hint = available.length ? ` Available agents: ${available.join(", ")}` : ""
-          const error = new NamedError.Unknown({ message: `Agent not found: "${task.agent}".${hint}` })
-          yield* bus.publish(Session.Event.Error, { sessionID, error: error.toObject() })
-          throw error
-        }
 
+        let child: SessionID | undefined
         let error: Error | undefined
-        const result = yield* Effect.promise((signal) =>
+        const result = yield* subtask(
-          taskTool
+          {
-            .execute(taskArgs, {
+            cfg: Effect.promise(() => Config.get()),
-              agent: task.agent,
+            get: (taskID) => sessions.get(SessionID.make(taskID)).pipe(Effect.catch(() => Effect.succeed(undefined))),
-              messageID: assistantMessage.id,
+            create: (input) => sessions.create(input),
-              sessionID,
+            resolve: resolvePromptParts,
-              abort: signal,
+            prompt: (input) => prompt({ ...input, messageID: MessageID.ascending() }),
-              callID: part.callID,
+          },
-              extra: { bypassAgentCheck: true },
+          {
-              messages: msgs,
+            parentID: sessionID,
-              metadata(val: { title?: string; metadata?: Record<string, any> }) {
+            description: task.description,
+            prompt: task.prompt,
+            agent: taskAgent,
+            model: taskRef,
+            start(sessionID, model) {
+              child = sessionID
+              const metadata = { sessionId: sessionID, model }
               return Effect.runPromise(
-                  Effect.gen(function* () {
+                sessions.updatePart({
-                    part = yield* sessions.updatePart({
                   ...part,
-                      type: "tool",
+                  state: {
-                      state: { ...part.state, ...val },
+                    status: "running",
-                    } satisfies MessageV2.ToolPart)
+                    input: part.state.input,
-                  }),
+                    time: part.state.status === "running" ? part.state.time : { start: Date.now() },
-                )
+                    title: task.description,
-              },
+                    metadata,
-              ask(req: any) {
-                return Effect.runPromise(
-                  permission.ask({
-                    ...req,
-                    sessionID,
-                    ruleset: Permission.merge(taskAgent.permission, session.permission ?? []),
-                  }),
-                )
                   },
+                } satisfies MessageV2.ToolPart),
+              ).then((next) => {
+                part = next
               })
-            .catch((e) => {
+            },
-              error = e instanceof Error ? e : new Error(String(e))
+          },
-              log.error("subtask execution failed", { error, agent: task.agent, description: task.description })
-              return undefined
-            }),
         ).pipe(
+          Effect.flatMap((sub) =>
+            truncate.output(subtaskOutput(sub.sessionID, sub.text), {}).pipe(
+              Effect.map((truncated) => ({
+                title: task.description,
+                metadata: {
+                  sessionId: sub.sessionID,
+                  model: sub.model,
+                  truncated: truncated.truncated,
+                  ...(truncated.truncated && { outputPath: truncated.outputPath }),
+                },
+                output: truncated.content,
+              })),
+            ),
+          ),
+          Effect.catchCause((cause) => {
+            const err = Cause.squash(cause)
+            error = err instanceof Error ? err : new Error(String(err))
+            log.error("subtask execution failed", { error, agent: task.agent, description: task.description })
+            return Effect.succeed(undefined)
+          }),
           Effect.onInterrupt(() =>
             Effect.gen(function* () {
+              if (child) yield* cancel(child)
               assistantMessage.finish = "tool-calls"
               assistantMessage.time.completed = Date.now()
               yield* sessions.updateMessage(assistantMessage)
@@ -671,16 +698,9 @@ NOTE: At any point in time through this workflow you should feel free to ask the
           ),
         )
 
-        const attachments = result?.attachments?.map((attachment) => ({
-          ...attachment,
-          id: PartID.ascending(),
-          sessionID,
-          messageID: assistantMessage.id,
-        }))
-
         yield* plugin.trigger(
           "tool.execute.after",
-          { tool: "task", sessionID, callID: part.id, args: taskArgs },
+          { tool: "task", sessionID, callID: part.callID, args: taskArgs },
           result,
         )
 
@@ -697,7 +717,6 @@ NOTE: At any point in time through this workflow you should feel free to ask the
               title: result.title,
               metadata: result.metadata,
               output: result.output,
-              attachments,
               time: { ...part.state.time, end: Date.now() },
             },
           } satisfies MessageV2.ToolPart)
@@ -740,7 +759,7 @@ NOTE: At any point in time through this workflow you should feel free to ask the
         } satisfies MessageV2.TextPart)
       })
 
-      const shellImpl = Effect.fn("SessionPrompt.shellImpl")(function* (input: ShellInput, signal: AbortSignal) {
+      const shellImpl = Effect.fn("SessionPrompt.shellImpl")(function* (input: ShellInput) {
         const ctx = yield* InstanceState.context
         const session = yield* sessions.get(input.sessionID)
         if (session.revert) {
@@ -1073,6 +1092,15 @@ NOTE: At any point in time through this workflow you should feel free to ask the
                 log.info("file", { mime: part.mime })
                 const filepath = fileURLToPath(part.url)
                 if (yield* fsys.isDir(filepath)) part.mime = "application/x-directory"
+                const readCtx = Tool.context({
+                  sessionID: input.sessionID,
+                  agent: info.agent,
+                  messageID: info.id,
+                  extra: { bypassCwdCheck: true },
+                  messages: [],
+                  metadata: () => {},
+                  ask: async () => {},
+                })
 
                 if (part.mime === "text/plain") {
                   let offset: number | undefined
@@ -1110,29 +1138,13 @@ NOTE: At any point in time through this workflow you should feel free to ask the
                       text: `Called the Read tool with the following input: ${JSON.stringify(args)}`,
                     },
                   ]
-                  const read = yield* Effect.promise(() => registry.named.read.init()).pipe(
+                  const readResult = yield* read(
-                    Effect.flatMap((t) =>
+                    { fs: fsys, instruction, lsp, time: filetime, scope },
-                      provider.getModel(info.model.providerID, info.model.modelID).pipe(
+                    args,
-                        Effect.flatMap((mdl) =>
+                    readCtx,
-                          Effect.promise(() =>
+                  ).pipe(Effect.exit)
-                            t.execute(args, {
+                  if (Exit.isSuccess(readResult)) {
-                              sessionID: input.sessionID,
+                    const result = readResult.value
-                              abort: new AbortController().signal,
-                              agent: input.agent!,
-                              messageID: info.id,
-                              extra: { bypassCwdCheck: true, model: mdl },
-                              messages: [],
-                              metadata: async () => {},
-                              ask: async () => {},
-                            }),
-                          ),
-                        ),
-                      ),
-                    ),
-                    Effect.exit,
-                  )
-                  if (Exit.isSuccess(read)) {
-                    const result = read.value
                     pieces.push({
                       messageID: info.id,
                       sessionID: input.sessionID,
@@ -1145,7 +1157,7 @@ NOTE: At any point in time through this workflow you should feel free to ask the
                         ...result.attachments.map((a) => ({
                           ...a,
                           synthetic: true,
-                          filename: a.filename ?? part.filename,
+                          filename: "filename" in a && typeof a.filename === "string" ? a.filename : part.filename,
                           messageID: info.id,
                           sessionID: input.sessionID,
                         })),
@@ -1154,7 +1166,7 @@ NOTE: At any point in time through this workflow you should feel free to ask the
                       pieces.push({ ...part, messageID: info.id, sessionID: input.sessionID })
                     }
                   } else {
-                    const error = Cause.squash(read.cause)
+                    const error = Cause.squash(readResult.cause)
                     log.error("failed to read file", { error })
                     const message = error instanceof Error ? error.message : String(error)
                     yield* bus.publish(Session.Event.Error, {
@@ -1174,21 +1186,8 @@ NOTE: At any point in time through this workflow you should feel free to ask the
 
                 if (part.mime === "application/x-directory") {
                   const args = { filePath: filepath }
-                  const result = yield* Effect.promise(() => registry.named.read.init()).pipe(
+                  const result = yield* read({ fs: fsys, instruction, lsp, time: filetime, scope }, args, readCtx).pipe(
-                    Effect.flatMap((t) =>
+                    Effect.orDie,
-                      Effect.promise(() =>
-                        t.execute(args, {
-                          sessionID: input.sessionID,
-                          abort: new AbortController().signal,
-                          agent: input.agent!,
-                          messageID: info.id,
-                          extra: { bypassCwdCheck: true },
-                          messages: [],
-                          metadata: async () => {},
-                          ask: async () => {},
-                        }),
-                      ),
-                    ),
                   )
                   return [
                     {
@@ -1332,7 +1331,7 @@ NOTE: At any point in time through this workflow you should feel free to ask the
           }
           if (latest) return latest
           throw new Error("Impossible")
-        })
+        }).pipe(Effect.orDie)
 
       const runLoop: (sessionID: SessionID) => Effect.Effect<MessageV2.WithParts> = Effect.fn("SessionPrompt.run")(
         function* (sessionID: SessionID) {
@@ -1393,7 +1392,7 @@ NOTE: At any point in time through this workflow you should feel free to ask the
             const task = tasks.pop()
 
             if (task?.type === "subtask") {
-              yield* handleSubtask({ task, model, lastUser, sessionID, session, msgs })
+              yield* handleSubtask({ task, model, lastUser, sessionID })
               continue
             }
 
@@ -1577,7 +1576,7 @@ NOTE: At any point in time through this workflow you should feel free to ask the
         function* (input: ShellInput) {
           const s = yield* InstanceState.get(state)
           const runner = getRunner(s.runners, input.sessionID)
-          return yield* runner.startShell((signal) => shellImpl(input, signal))
+          return yield* runner.startShell(shellImpl(input))
         },
       )
 
@@ -1722,6 +1721,7 @@ NOTE: At any point in time through this workflow you should feel free to ask the
         Layer.provide(FileTime.defaultLayer),
         Layer.provide(ToolRegistry.defaultLayer),
         Layer.provide(Truncate.layer),
+        Layer.provide(LLM.defaultLayer),
         Layer.provide(Provider.defaultLayer),
         Layer.provide(Instruction.defaultLayer),
         Layer.provide(AppFileSystem.defaultLayer),

packages/opencode/src/tool/external-directory.ts

@@ -11,7 +11,9 @@ type Options = {
   kind?: Kind
 }
 
-export async function assertExternalDirectory(ctx: Tool.Context, target?: string, options?: Options) {
+type Ctx = Pick<Tool.Context, "ask">
+
+export async function assertExternalDirectory(ctx: Ctx, target?: string, options?: Options) {
   if (!target) return
 
   if (options?.bypass) return
@@ -38,7 +40,7 @@ export async function assertExternalDirectory(ctx: Tool.Context, target?: string
 }
 
 export const assertExternalDirectoryEffect = Effect.fn("Tool.assertExternalDirectory")(function* (
-  ctx: Tool.Context,
+  ctx: Ctx,
   target?: string,
   options?: Options,
 ) {

packages/opencode/src/tool/read.ts

@@ -25,19 +25,21 @@ const parameters = z.object({
   limit: z.coerce.number().describe("The maximum number of lines to read (defaults to 2000)").optional(),
 })
 
-export const ReadTool = Tool.defineEffect(
+type Ctx = Omit<Tool.Context, "abort">
-  "read",
-  Effect.gen(function* () {
-    const fs = yield* AppFileSystem.Service
-    const instruction = yield* Instruction.Service
-    const lsp = yield* LSP.Service
-    const time = yield* FileTime.Service
-    const scope = yield* Scope.Scope
 
+type Deps = {
+  fs: AppFileSystem.Interface
+  instruction: Instruction.Interface
+  lsp: LSP.Interface
+  time: FileTime.Interface
+  scope: Scope.Scope
+}
+
+export const run = Effect.fn("ReadTool.run")(function* (deps: Deps, params: z.infer<typeof parameters>, ctx: Ctx) {
   const miss = Effect.fn("ReadTool.miss")(function* (filepath: string) {
     const dir = path.dirname(filepath)
     const base = path.basename(filepath)
-      const items = yield* fs.readDirectory(dir).pipe(
+    const items = yield* deps.fs.readDirectory(dir).pipe(
       Effect.map((items) =>
         items
           .filter(
@@ -60,14 +62,14 @@ export const ReadTool = Tool.defineEffect(
   })
 
   const list = Effect.fn("ReadTool.list")(function* (filepath: string) {
-      const items = yield* fs.readDirectoryEntries(filepath)
+    const items = yield* deps.fs.readDirectoryEntries(filepath)
     return yield* Effect.forEach(
       items,
       Effect.fnUntraced(function* (item) {
         if (item.type === "directory") return item.name + "/"
         if (item.type !== "symlink") return item.name
 
-          const target = yield* fs
+        const target = yield* deps.fs
           .stat(path.join(filepath, item.name))
           .pipe(Effect.catch(() => Effect.succeed(undefined)))
         if (target?.type === "Directory") return item.name + "/"
@@ -77,12 +79,11 @@ export const ReadTool = Tool.defineEffect(
     ).pipe(Effect.map((items: string[]) => items.sort((a, b) => a.localeCompare(b))))
   })
 
-    const warm = Effect.fn("ReadTool.warm")(function* (filepath: string, sessionID: Tool.Context["sessionID"]) {
+  const warm = Effect.fn("ReadTool.warm")(function* (filepath: string, sessionID: Ctx["sessionID"]) {
-      yield* lsp.touchFile(filepath, false).pipe(Effect.ignore, Effect.forkIn(scope))
+    yield* deps.lsp.touchFile(filepath, false).pipe(Effect.ignore, Effect.forkIn(deps.scope))
-      yield* time.read(sessionID, filepath)
+    yield* deps.time.read(sessionID, filepath)
   })
 
-    const run = Effect.fn("ReadTool.execute")(function* (params: z.infer<typeof parameters>, ctx: Tool.Context) {
   if (params.offset !== undefined && params.offset < 1) {
     return yield* Effect.fail(new Error("offset must be greater than or equal to 1"))
   }
@@ -96,7 +97,7 @@ export const ReadTool = Tool.defineEffect(
   }
   const title = path.relative(Instance.worktree, filepath)
 
-      const stat = yield* fs.stat(filepath).pipe(
+  const stat = yield* deps.fs.stat(filepath).pipe(
     Effect.catchIf(
       (err) => "reason" in err && err.reason._tag === "NotFound",
       () => Effect.succeed(undefined),
@@ -147,7 +148,7 @@ export const ReadTool = Tool.defineEffect(
     }
   }
 
-      const loaded = yield* instruction.resolve(ctx.messages, filepath, ctx.messageID)
+  const loaded = yield* deps.instruction.resolve(ctx.messages, filepath, ctx.messageID)
 
   const mime = AppFileSystem.mimeType(filepath)
   const isImage = mime.startsWith("image/") && mime !== "image/svg+xml" && mime !== "image/vnd.fastbidsheet"
@@ -166,7 +167,7 @@ export const ReadTool = Tool.defineEffect(
         {
           type: "file" as const,
           mime,
-              url: `data:${mime};base64,${Buffer.from(yield* fs.readFile(filepath)).toString("base64")}`,
+          url: `data:${mime};base64,${Buffer.from(yield* deps.fs.readFile(filepath)).toString("base64")}`,
         },
       ],
     }
@@ -180,9 +181,7 @@ export const ReadTool = Tool.defineEffect(
     lines(filepath, { limit: params.limit ?? DEFAULT_READ_LIMIT, offset: params.offset ?? 1 }),
   )
   if (file.count < file.offset && !(file.count === 0 && file.offset === 1)) {
-        return yield* Effect.fail(
+    return yield* Effect.fail(new Error(`Offset ${file.offset} is out of range for this file (${file.count} lines)`))
-          new Error(`Offset ${file.offset} is out of range for this file (${file.count} lines)`),
-        )
   }
 
   let output = [`<path>${filepath}</path>`, `<type>file</type>`, "<content>"].join("\n")
@@ -217,11 +216,21 @@ export const ReadTool = Tool.defineEffect(
   }
 })
 
+export const ReadTool = Tool.defineEffect(
+  "read",
+  Effect.gen(function* () {
+    const fs = yield* AppFileSystem.Service
+    const instruction = yield* Instruction.Service
+    const lsp = yield* LSP.Service
+    const time = yield* FileTime.Service
+    const scope = yield* Scope.Scope
+    const deps = { fs, instruction, lsp, time, scope } satisfies Deps
+
     return {
       description: DESCRIPTION,
       parameters,
       async execute(params: z.infer<typeof parameters>, ctx) {
-        return Effect.runPromise(run(params, ctx).pipe(Effect.orDie))
+        return Effect.runPromise(run(deps, params, ctx).pipe(Effect.orDie))
       },
     }
   }),

packages/opencode/src/tool/subtask.ts

@@ -0,0 +1,102 @@
+import type { Agent } from "../agent/agent"
+import { Config } from "../config/config"
+import { Session } from "../session"
+import { SessionPrompt } from "../session/prompt"
+import { SessionID } from "../session/schema"
+import type { ModelID, ProviderID } from "../provider/schema"
+import { Effect } from "effect"
+
+type Ref = {
+  providerID: ProviderID
+  modelID: ModelID
+}
+
+type Parts = Awaited<ReturnType<typeof SessionPrompt.resolvePromptParts>>
+type Reply = Awaited<ReturnType<typeof SessionPrompt.prompt>>
+
+type Deps = {
+  cfg: Effect.Effect<Config.Info>
+  get: (taskID: string) => Effect.Effect<Session.Info | undefined>
+  create: (input: { parentID: SessionID; title: string }) => Effect.Effect<Session.Info>
+  resolve: (prompt: string) => Effect.Effect<Parts>
+  prompt: (input: {
+    sessionID: SessionID
+    model: Ref
+    agent: string
+    tools: Record<string, boolean>
+    parts: Parts
+  }) => Effect.Effect<Reply>
+}
+
+type Input = {
+  parentID: SessionID
+  taskID?: string
+  description: string
+  prompt: string
+  agent: Agent.Info
+  model: Ref
+  abort?: AbortSignal
+  cancel?: (sessionID: SessionID) => Promise<void> | void
+  start?: (sessionID: SessionID, model: Ref) => Promise<void> | void
+}
+
+export function tools(agent: Agent.Info, cfg: Config.Info) {
+  const task = agent.permission.some((rule) => rule.permission === "task")
+  const todo = agent.permission.some((rule) => rule.permission === "todowrite")
+  return {
+    ...(todo ? {} : { todowrite: false }),
+    ...(task ? {} : { task: false }),
+    ...Object.fromEntries((cfg.experimental?.primary_tools ?? []).map((tool) => [tool, false])),
+  }
+}
+
+export function output(sessionID: SessionID, text: string) {
+  return [
+    `task_id: ${sessionID} (for resuming to continue this task if needed)`,
+    "",
+    "<task_result>",
+    text,
+    "</task_result>",
+  ].join("\n")
+}
+
+export const run = Effect.fn("Subtask.run")(function* (deps: Deps, input: Input) {
+  const cfg = yield* deps.cfg
+  const model = input.agent.model ?? input.model
+  const session = yield* Effect.uninterruptibleMask((restore) =>
+    Effect.gen(function* () {
+      const found = input.taskID ? yield* restore(deps.get(input.taskID)) : undefined
+      const session = found
+        ? found
+        : yield* restore(
+            deps.create({
+              parentID: input.parentID,
+              title: input.description + ` (@${input.agent.name} subagent)`,
+            }),
+          )
+
+      const start = input.start?.(session.id, model)
+      if (start) yield* Effect.promise(() => Promise.resolve(start))
+      return session
+    }),
+  )
+
+  if (input.abort?.aborted) {
+    const cancel = input.cancel?.(session.id)
+    if (cancel) yield* Effect.promise(() => Promise.resolve(cancel))
+  }
+
+  const result = yield* deps.prompt({
+    sessionID: session.id,
+    model,
+    agent: input.agent.name,
+    tools: tools(input.agent, cfg),
+    parts: yield* deps.resolve(input.prompt),
+  })
+
+  return {
+    sessionID: session.id,
+    model,
+    text: result.parts.findLast((part) => part.type === "text")?.text ?? "",
+  }
+})

packages/opencode/src/tool/task.ts

@@ -1,16 +1,17 @@
 import { Tool } from "./tool"
 import DESCRIPTION from "./task.txt"
 import z from "zod"
-import { Session } from "../session"
+import { Effect } from "effect"
-import { SessionID, MessageID } from "../session/schema"
-import { MessageV2 } from "../session/message-v2"
-import { Identifier } from "../id/id"
-import { Agent } from "../agent/agent"
-import { SessionPrompt } from "../session/prompt"
-import { iife } from "@/util/iife"
-import { defer } from "@/util/defer"
 import { Config } from "../config/config"
+import { Session } from "../session"
+import { SessionPrompt } from "../session/prompt"
+import { MessageV2 } from "../session/message-v2"
+import { Agent } from "../agent/agent"
+import type { SessionID } from "../session/schema"
+import { MessageID, SessionID as SessionRef } from "../session/schema"
+import { defer } from "@/util/defer"
 import { Permission } from "@/permission"
+import { output, run } from "./subtask"
 
 const parameters = z.object({
   description: z.string().describe("A short (3-5 words) description of the task"),
@@ -45,8 +46,6 @@ export const TaskTool = Tool.define("task", async (ctx) => {
     description,
     parameters,
     async execute(params: z.infer<typeof parameters>, ctx) {
-      const config = await Config.get()
-
       // Skip permission check when user explicitly invoked via @ or command subtask
       if (!ctx.extra?.bypassAgentCheck) {
         await ctx.ask({
@@ -62,104 +61,60 @@ export const TaskTool = Tool.define("task", async (ctx) => {
 
       const agent = await Agent.get(params.subagent_type)
       if (!agent) throw new Error(`Unknown agent type: ${params.subagent_type} is not a valid agent type`)
-
-      const hasTaskPermission = agent.permission.some((rule) => rule.permission === "task")
-      const hasTodoWritePermission = agent.permission.some((rule) => rule.permission === "todowrite")
-
-      const session = await iife(async () => {
-        if (params.task_id) {
-          const found = await Session.get(SessionID.make(params.task_id)).catch(() => {})
-          if (found) return found
-        }
-
-        return await Session.create({
-          parentID: ctx.sessionID,
-          title: params.description + ` (@${agent.name} subagent)`,
-          permission: [
-            ...(hasTodoWritePermission
-              ? []
-              : [
-                  {
-                    permission: "todowrite" as const,
-                    pattern: "*" as const,
-                    action: "deny" as const,
-                  },
-                ]),
-            ...(hasTaskPermission
-              ? []
-              : [
-                  {
-                    permission: "task" as const,
-                    pattern: "*" as const,
-                    action: "deny" as const,
-                  },
-                ]),
-            ...(config.experimental?.primary_tools?.map((t) => ({
-              pattern: "*",
-              action: "allow" as const,
-              permission: t,
-            })) ?? []),
-          ],
-        })
-      })
       const msg = await MessageV2.get({ sessionID: ctx.sessionID, messageID: ctx.messageID })
       if (msg.info.role !== "assistant") throw new Error("Not an assistant message")
 
-      const model = agent.model ?? {
+      let child: SessionID | undefined
-        modelID: msg.info.modelID,
+      const cancel = () => {
-        providerID: msg.info.providerID,
+        if (!child) return
-      }
+        SessionPrompt.cancel(child)
-
-      ctx.metadata({
-        title: params.description,
-        metadata: {
-          sessionId: session.id,
-          model,
-        },
-      })
-
-      const messageID = MessageID.ascending()
-
-      function cancel() {
-        SessionPrompt.cancel(session.id)
       }
       ctx.abort.addEventListener("abort", cancel)
       using _ = defer(() => ctx.abort.removeEventListener("abort", cancel))
-      const promptParts = await SessionPrompt.resolvePromptParts(params.prompt)
 
-      const result = await SessionPrompt.prompt({
+      const task = await Effect.runPromise(
-        messageID,
+        run(
-        sessionID: session.id,
+          {
+            cfg: Effect.promise(() => Config.get()),
+            get: (taskID) => Effect.promise(() => Session.get(SessionRef.make(taskID)).catch(() => undefined)),
+            create: (input) => Effect.promise(() => Session.create(input)),
+            resolve: (prompt) => Effect.promise(() => SessionPrompt.resolvePromptParts(prompt)),
+            prompt: (input) =>
+              Effect.promise(() => SessionPrompt.prompt({ ...input, messageID: MessageID.ascending() })),
+          },
+          {
+            parentID: ctx.sessionID,
+            taskID: params.task_id,
+            description: params.description,
+            prompt: params.prompt,
+            agent,
+            abort: ctx.abort,
+            cancel: SessionPrompt.cancel,
             model: {
-          modelID: model.modelID,
+              modelID: msg.info.modelID,
-          providerID: model.providerID,
+              providerID: msg.info.providerID,
             },
-        agent: agent.name,
+            start(sessionID, model) {
-        tools: {
+              child = sessionID
-          ...(hasTodoWritePermission ? {} : { todowrite: false }),
+              ctx.metadata({
-          ...(hasTaskPermission ? {} : { task: false }),
+                title: params.description,
-          ...Object.fromEntries((config.experimental?.primary_tools ?? []).map((t) => [t, false])),
+                metadata: {
+                  sessionId: sessionID,
+                  model,
                 },
-        parts: promptParts,
               })
-
+            },
-      const text = result.parts.findLast((x) => x.type === "text")?.text ?? ""
+          },
-
+        ),
-      const output = [
+      )
-        `task_id: ${session.id} (for resuming to continue this task if needed)`,
-        "",
-        "<task_result>",
-        text,
-        "</task_result>",
-      ].join("\n")
 
       return {
         title: params.description,
         metadata: {
-          sessionId: session.id,
+          sessionId: task.sessionID,
-          model,
+          model: task.model,
         },
-        output,
+        output: output(task.sessionID, task.text),
       }
     },
   }

packages/opencode/src/tool/tool.ts

@@ -26,6 +26,20 @@ export namespace Tool {
     metadata(input: { title?: string; metadata?: M }): void
     ask(input: Omit<Permission.Request, "id" | "sessionID" | "tool">): Promise<void>
   }
+
+  export function context<M extends Metadata = Metadata>(
+    input: Omit<Context<M>, "abort" | "callID"> & {
+      abort?: AbortSignal
+      callID?: string
+    },
+  ): Context<M> {
+    return {
+      ...input,
+      abort: input.abort ?? new AbortController().signal,
+      callID: input.callID,
+    }
+  }
+
   export interface Def<Parameters extends z.ZodType = z.ZodType, M extends Metadata = Metadata> {
     description: string
     parameters: Parameters

packages/opencode/test/effect/runner.test.ts

@@ -250,7 +250,7 @@ describe("Runner", () => {
     Effect.gen(function* () {
       const s = yield* Scope.Scope
       const runner = Runner.make<string>(s)
-      const result = yield* runner.startShell((_signal) => Effect.succeed("shell-done"))
+      const result = yield* runner.startShell(Effect.succeed("shell-done"))
       expect(result).toBe("shell-done")
       expect(runner.busy).toBe(false)
     }),
@@ -264,7 +264,7 @@ describe("Runner", () => {
       const fiber = yield* runner.ensureRunning(Effect.never.pipe(Effect.as("x"))).pipe(Effect.forkChild)
       yield* Effect.sleep("10 millis")
 
-      const exit = yield* runner.startShell((_s) => Effect.succeed("nope")).pipe(Effect.exit)
+      const exit = yield* runner.startShell(Effect.succeed("nope")).pipe(Effect.exit)
       expect(Exit.isFailure(exit)).toBe(true)
 
       yield* runner.cancel
@@ -279,12 +279,10 @@ describe("Runner", () => {
       const runner = Runner.make<string>(s)
       const gate = yield* Deferred.make<void>()
 
-      const sh = yield* runner
+      const sh = yield* runner.startShell(Deferred.await(gate).pipe(Effect.as("first"))).pipe(Effect.forkChild)
-        .startShell((_signal) => Deferred.await(gate).pipe(Effect.as("first")))
-        .pipe(Effect.forkChild)
       yield* Effect.sleep("10 millis")
 
-      const exit = yield* runner.startShell((_s) => Effect.succeed("second")).pipe(Effect.exit)
+      const exit = yield* runner.startShell(Effect.succeed("second")).pipe(Effect.exit)
       expect(Exit.isFailure(exit)).toBe(true)
 
       yield* Deferred.succeed(gate, undefined)
@@ -302,37 +300,26 @@ describe("Runner", () => {
         },
       })
 
-      const sh = yield* runner
+      const sh = yield* runner.startShell(Effect.never.pipe(Effect.as("aborted"))).pipe(Effect.forkChild)
-        .startShell((signal) =>
-          Effect.promise(
-            () =>
-              new Promise<string>((resolve) => {
-                signal.addEventListener("abort", () => resolve("aborted"), { once: true })
-              }),
-          ),
-        )
-        .pipe(Effect.forkChild)
       yield* Effect.sleep("10 millis")
 
-      const exit = yield* runner.startShell((_s) => Effect.succeed("second")).pipe(Effect.exit)
+      const exit = yield* runner.startShell(Effect.succeed("second")).pipe(Effect.exit)
       expect(Exit.isFailure(exit)).toBe(true)
 
       yield* runner.cancel
       const done = yield* Fiber.await(sh)
-      expect(Exit.isSuccess(done)).toBe(true)
+      expect(Exit.isFailure(done)).toBe(true)
     }),
   )
 
   it.live(
-    "cancel interrupts shell that ignores abort signal",
+    "cancel interrupts shell",
     Effect.gen(function* () {
       const s = yield* Scope.Scope
       const runner = Runner.make<string>(s)
       const gate = yield* Deferred.make<void>()
 
-      const sh = yield* runner
+      const sh = yield* runner.startShell(Deferred.await(gate).pipe(Effect.as("ignored"))).pipe(Effect.forkChild)
-        .startShell((_signal) => Deferred.await(gate).pipe(Effect.as("ignored")))
-        .pipe(Effect.forkChild)
       yield* Effect.sleep("10 millis")
 
       const stop = yield* runner.cancel.pipe(Effect.forkChild)
@@ -356,9 +343,7 @@ describe("Runner", () => {
       const runner = Runner.make<string>(s)
       const gate = yield* Deferred.make<void>()
 
-      const sh = yield* runner
+      const sh = yield* runner.startShell(Deferred.await(gate).pipe(Effect.as("shell-result"))).pipe(Effect.forkChild)
-        .startShell((_signal) => Deferred.await(gate).pipe(Effect.as("shell-result")))
-        .pipe(Effect.forkChild)
       yield* Effect.sleep("10 millis")
       expect(runner.state._tag).toBe("Shell")
 
@@ -384,9 +369,7 @@ describe("Runner", () => {
       const calls = yield* Ref.make(0)
       const gate = yield* Deferred.make<void>()
 
-      const sh = yield* runner
+      const sh = yield* runner.startShell(Deferred.await(gate).pipe(Effect.as("shell"))).pipe(Effect.forkChild)
-        .startShell((_signal) => Deferred.await(gate).pipe(Effect.as("shell")))
-        .pipe(Effect.forkChild)
       yield* Effect.sleep("10 millis")
 
       const work = Effect.gen(function* () {
@@ -414,16 +397,7 @@ describe("Runner", () => {
       const runner = Runner.make<string>(s)
       const gate = yield* Deferred.make<void>()
 
-      const sh = yield* runner
+      const sh = yield* runner.startShell(Effect.never.pipe(Effect.as("aborted"))).pipe(Effect.forkChild)
-        .startShell((signal) =>
-          Effect.promise(
-            () =>
-              new Promise<string>((resolve) => {
-                signal.addEventListener("abort", () => resolve("aborted"), { once: true })
-              }),
-          ),
-        )
-        .pipe(Effect.forkChild)
       yield* Effect.sleep("10 millis")
 
       const run = yield* runner.ensureRunning(Effect.succeed("y")).pipe(Effect.forkChild)
@@ -478,7 +452,7 @@ describe("Runner", () => {
       const runner = Runner.make<string>(s, {
         onBusy: Ref.update(count, (n) => n + 1),
       })
-      yield* runner.startShell((_signal) => Effect.succeed("done"))
+      yield* runner.startShell(Effect.succeed("done"))
       expect(yield* Ref.get(count)).toBe(1)
     }),
   )
@@ -509,9 +483,7 @@ describe("Runner", () => {
       const runner = Runner.make<string>(s)
       const gate = yield* Deferred.make<void>()
 
-      const fiber = yield* runner
+      const fiber = yield* runner.startShell(Deferred.await(gate).pipe(Effect.as("ok"))).pipe(Effect.forkChild)
-        .startShell((_signal) => Deferred.await(gate).pipe(Effect.as("ok")))
-        .pipe(Effect.forkChild)
       yield* Effect.sleep("10 millis")
       expect(runner.busy).toBe(true)
 

packages/opencode/test/session/prompt-effect.test.ts

@@ -1,8 +1,7 @@
 import { NodeFileSystem } from "@effect/platform-node"
-import { expect, spyOn } from "bun:test"
+import { expect } from "bun:test"
 import { Cause, Effect, Exit, Fiber, Layer } from "effect"
 import path from "path"
-import z from "zod"
 import { Agent as AgentSvc } from "../../src/agent/agent"
 import { Bus } from "../../src/bus"
 import { Command } from "../../src/command"
@@ -29,7 +28,6 @@ import { MessageID, PartID, SessionID } from "../../src/session/schema"
 import { SessionStatus } from "../../src/session/status"
 import { Shell } from "../../src/shell/shell"
 import { Snapshot } from "../../src/snapshot"
-import { TaskTool } from "../../src/tool/task"
 import { ToolRegistry } from "../../src/tool/registry"
 import { Truncate } from "../../src/tool/truncate"
 import { Log } from "../../src/util/log"
@@ -629,41 +627,26 @@ it.live(
     provideTmpdirInstance(
       (dir) =>
         Effect.gen(function* () {
-          const ready = defer<void>()
+          const { prompt, chat, sessions } = yield* boot()
-          const aborted = defer<void>()
+          const llm = yield* TestLLMServer
-          const init = spyOn(TaskTool, "init").mockImplementation(async () => ({
+          yield* llm.hang
-            description: "task",
-            parameters: z.object({
-              description: z.string(),
-              prompt: z.string(),
-              subagent_type: z.string(),
-              task_id: z.string().optional(),
-              command: z.string().optional(),
-            }),
-            execute: async (_args, ctx) => {
-              ready.resolve()
-              ctx.abort.addEventListener("abort", () => aborted.resolve(), { once: true })
-              await new Promise<void>(() => {})
-              return {
-                title: "",
-                metadata: {
-                  sessionId: SessionID.make("task"),
-                  model: ref,
-                },
-                output: "",
-              }
-            },
-          }))
-          yield* Effect.addFinalizer(() => Effect.sync(() => init.mockRestore()))
-
-          const { prompt, chat } = yield* boot()
           const msg = yield* user(chat.id, "hello")
           yield* addSubtask(chat.id, msg.id)
 
           const fiber = yield* prompt.loop({ sessionID: chat.id }).pipe(Effect.forkChild)
-          yield* Effect.promise(() => ready.promise)
+
+          yield* Effect.gen(function* () {
+            while (true) {
+              const [child] = yield* sessions.children(chat.id)
+              if (child) {
+                const msgs = yield* sessions.messages({ sessionID: child.id })
+                if (msgs.some((msg) => msg.info.role === "assistant")) return
+              }
+              yield* Effect.sleep("10 millis")
+            }
+          })
+
           yield* prompt.cancel(chat.id)
-          yield* Effect.promise(() => aborted.promise)
 
           const exit = yield* Fiber.await(fiber)
           expect(Exit.isSuccess(exit)).toBe(true)

packages/opencode/test/tool/task.test.ts

@@ -1,13 +1,28 @@
-import { afterEach, describe, expect, test } from "bun:test"
+import { afterEach, describe, expect, mock, spyOn, test } from "bun:test"
 import { Agent } from "../../src/agent/agent"
+import { Config } from "../../src/config/config"
 import { Instance } from "../../src/project/instance"
+import { ModelID, ProviderID } from "../../src/provider/schema"
+import { MessageV2 } from "../../src/session/message-v2"
+import { SessionPrompt } from "../../src/session/prompt"
+import { MessageID, SessionID } from "../../src/session/schema"
+import { Session } from "../../src/session"
 import { TaskTool } from "../../src/tool/task"
 import { tmpdir } from "../fixture/fixture"
 
 afterEach(async () => {
+  mock.restore()
   await Instance.disposeAll()
 })
 
+function wait<T>() {
+  let done!: (value: T | PromiseLike<T>) => void
+  const promise = new Promise<T>((resolve) => {
+    done = resolve
+  })
+  return { promise, done }
+}
+
 describe("tool.task", () => {
   test("description sorts subagents by name and is stable across calls", async () => {
     await using tmp = await tmpdir({
@@ -46,4 +61,73 @@ describe("tool.task", () => {
       },
     })
   })
+
+  test("cancels child session when aborted during creation", async () => {
+    const started = wait<void>()
+    const gate = wait<void>()
+    const parent = SessionID.make("parent")
+    const child = SessionID.make("child")
+    const messageID = MessageID.ascending()
+    const abort = new AbortController()
+    const agent: Agent.Info = {
+      name: "general",
+      description: "General agent",
+      mode: "subagent",
+      options: {},
+      permission: [],
+    }
+    const ref = {
+      providerID: ProviderID.make("test"),
+      modelID: ModelID.make("test-model"),
+    }
+
+    spyOn(Agent, "list").mockResolvedValue([agent])
+    spyOn(Agent, "get").mockResolvedValue(agent)
+    spyOn(Config, "get").mockResolvedValue({ experimental: {} } as Awaited<ReturnType<typeof Config.get>>)
+    spyOn(MessageV2, "get").mockResolvedValue({
+      info: {
+        role: "assistant",
+        providerID: ref.providerID,
+        modelID: ref.modelID,
+      },
+    } as Awaited<ReturnType<typeof MessageV2.get>>)
+    spyOn(Session, "get").mockRejectedValue(new Error("missing"))
+    spyOn(Session, "create").mockImplementation(async () => {
+      started.done()
+      await gate.promise
+      return { id: child } as Awaited<ReturnType<typeof Session.create>>
+    })
+    const cancel = spyOn(SessionPrompt, "cancel").mockResolvedValue()
+    spyOn(SessionPrompt, "resolvePromptParts").mockResolvedValue(
+      [] as Awaited<ReturnType<typeof SessionPrompt.resolvePromptParts>>,
+    )
+    spyOn(SessionPrompt, "prompt").mockResolvedValue({
+      parts: [{ type: "text", text: "done" }],
+    } as Awaited<ReturnType<typeof SessionPrompt.prompt>>)
+
+    const tool = await TaskTool.init()
+    const run = tool.execute(
+      {
+        description: "inspect bug",
+        prompt: "check it",
+        subagent_type: "general",
+      },
+      {
+        sessionID: parent,
+        messageID,
+        agent: "build",
+        abort: abort.signal,
+        messages: [],
+        metadata: () => {},
+        ask: async () => {},
+      },
+    )
+
+    await started.promise
+    abort.abort()
+    gate.done()
+    await run
+
+    expect(cancel).toHaveBeenCalledWith(child)
+  })
 })