fix(tasks-local): layer control surfaces and listeners by registering scope

One host registry serves every composition in the process, so its two
service-wide collections answered per-owner questions process-wide. `start()`
asked only whether SOME surface was attached, so an agent whose own composition
loads no `tool-tasks` could start work it has no tool to collect or stop as soon
as any other preset attached one — and the answer changed depending on which
sessions happened to be open. `settle()` walked every registered listener, so a
task settling without a waiter injected one completion notice per mounted
preset into the same owner.

Both collections now sit in `ScopedLayers`, the layered-registry primitive
`tools` and `skills` already use: a registration files into its registering
context's scope, and a read unions the global layer with the owner's scope
chain. A surface or listener registered from an unscoped context lands in the
global layer and serves every owner, which is exactly the host-plane
composition's own controls, so the TUI path is unchanged without a special
case.

This supersedes the consumer-side filter in the previous commit. That filter
produced the right notices but sat in the wrong layer: it left the `start()`
gate process-wide, it could not be enforced against a producer that resolves
the registry directly, and it made a Consumer carry scope knowledge that the
other layered registries keep in the registry. `tool-tasks` is scope-agnostic
again and the `dsh-scope` edge moves to `tasks-local`.

`start()`'s refusal is now owner-relative, so its model-visible text names the
agent rather than the process. The shipped `minimal` preset keeps
`enableRunInBackground: false`, no longer as the safety boundary — the registry
owns that now — but so an agent that could never collect a task is not offered
the parameter at all.

Refs #2141

packages/tasks/tasks/README.i18n.yaml

@@ -2,5 +2,5 @@
 # side as of the last confirmed-consistent state. Both languages carry equal authority;
 # after editing either side, bring the other along and re-record with:
 #   pnpm run verify-translation-pairing --write packages/tasks/tasks/README.md
-README.md: 04ca125580104d0cb5ab0ce8cdd20d104c4a1668
-README.zh.md: b0b079566246549c7acab7a83fcc3c21c44ef868
+README.md: f23a93e3cb1fc5aad5bad053f832bb66baa8eb64
+README.zh.md: c3ea9125c4db9f2d86722cbf490b4f0eecfbe25a

packages/tasks/tasks/README.md

@@ -12,7 +12,9 @@ The background task registry contract (`ctx.tasks`). The abstract `TaskService`
 - `kill(id, caller?, reason?)` invokes producer cancellation before changing status. A cancellation throw leaves the task running; success changes it to `stopping` and marks terminal delivery reported.
 - `wait(id, timeoutMs, caller?, signal?)` returns a terminal snapshot or the live snapshot at timeout. Aborting stops only the wait; settlement wins once it has committed terminal delivery to that waiter.
 - `onTaskDone(listener)` observes each terminal record with the exact owner. Listener throws and rejections are contained; listener work is not awaited.
-- `attachSurface(name)` declares a control surface for its effect lifetime. `start()` fails before producer execution when none is attached.
+- `attachSurface(name)` declares a control surface for its effect lifetime. `start()` fails before producer execution when no attached surface serves the spec's owner.
+
+Both registrations are owner-relative, because one registry serves every composition in the process. A surface or listener registered from an unscoped context serves every owner; one registered under an agent composition's scope serves exactly the agents composed under it. So a composition that loads no control surface cannot start background work on the strength of another composition's controls, and one settlement notifies only the listeners its owner's composition registered.
 
 Owned access compares the task's `SessionId` with the caller's. Ids such as `bash-1` are predictable, so this fence is the boundary. Unowned tasks are open to callers and last until service disposal.
 

packages/tasks/tasks/README.zh.md

@@ -12,7 +12,9 @@
 - `kill(id, caller?, reason?)` 在更改状态前调用生产方取消。取消抛出异常时任务保持运行；成功则把状态改为 `stopping`，并将终止交付标记为已报告。
 - `wait(id, timeoutMs, caller?, signal?)` 返回终止快照，或在超时时返回存活快照。中止只会停止等待；一旦终止交付已向该等待方提交，终止结果优先。
 - `onTaskDone(listener)` 观察每条终止记录及其精确 owner。监听器抛出的异常和产生的拒绝都会被隔离；系统不会等待监听器工作。
-- `attachSurface(name)` 在其 effect 生命周期内声明控制表层。如果没有附加任何表层，`start()` 会在生产方执行前失败。
+- `attachSurface(name)` 在其 effect 生命周期内声明控制表层。当没有任何已附加的表层服务于 spec 的所有者时，`start()` 会在生产方执行前失败。
+
+这两类注册都是相对于所有者的，因为一个注册表要服务进程内的每一套组合。从不带 scope 的上下文注册的表层或监听器服务于每个所有者；在某套 agent 组合的 scope 下注册的，则恰好服务于在该组合下组合出的 agent。因此，未加载任何控制表层的组合无法借另一套组合的控制工具启动后台工作，而一次结算也只会通知其所有者所属组合注册的监听器。
 
 有 owner 的访问会比较任务的 `SessionId` 与调用方。`bash-1` 等 id 可预测，因此这道隔离是安全边界。无 owner 的任务向调用方开放，并持续到服务释放。
 

packages/tasks/tasks/src/index.ts

@@ -44,8 +44,13 @@ declare module 'cordis' {
  * - Settlement is first-wins: one terminal record, one round of contained
  *   listener notification, and released waiters, even against a late
  *   producer outcome.
- * - {@link start} refuses work while no control surface is attached, so a
- *   producer cannot start work that callers cannot collect or stop.
+ * - {@link start} refuses work while no attached control surface serves the
+ *   spec's owner, so a producer cannot start work that owner cannot collect
+ *   or stop. One registry serves every composition in the process, so this
+ *   question — and completion-listener delivery — is owner-relative rather
+ *   than process-wide: registrations made from an unscoped context serve
+ *   every owner, and registrations made under an agent composition's scope
+ *   serve exactly the agents composed under it.
  */
 export abstract class TaskService extends Service {
   constructor(ctx: Context) {
@@ -120,17 +125,19 @@ export abstract class TaskService extends Service {
   abstract wait(id: TaskId, timeoutMs: number, caller?: Agent, signal?: AbortSignal): Promise<TaskSnapshot>
 
   /**
-   * Register an effect-scoped completion listener. Each listener is contained;
-   * returned promises are observed but not awaited. No listener runs after
-   * service disposal.
+   * Register an effect-scoped completion listener. It receives the settlements
+   * of the owners its registering context's scope covers; each listener is
+   * contained; returned promises are observed but not awaited. No listener runs
+   * after service disposal.
    * @param listener - receives each terminal snapshot and its exact owner.
    * @returns disposer that unregisters the listener.
    */
   abstract onTaskDone(listener: TaskDoneListener): () => void
 
   /**
-   * Attach an effect-scoped surface that can read and stop tasks. {@link start}
-   * refuses work while none is attached.
+   * Attach an effect-scoped surface that can read and stop tasks. It serves the
+   * owners its registering context's scope covers, and {@link start} refuses an
+   * owner no attached surface serves.
    * @param name - diagnostic label; duplicate names remain independent.
    * @returns disposer that detaches this surface.
    */