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

docs/subsystems/tasks.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 docs/subsystems/tasks.md
-tasks.md: d3e92891a6736a85519b97775ebe7aa6f12a5ae2
-tasks.zh.md: fe54d7a6482743a8f2ef31b143edb25afe0a478b
+tasks.md: 51b21b6d81905f1dede2a1c748a417425d2aaf4e
+tasks.zh.md: 045f4e438b2b384439826ecca0782349d7aaae27

docs/subsystems/tasks.md

@@ -172,7 +172,7 @@ Implementations must honor these semantics:
 - Registrations outlive producer and control-surface fibers. Owner and service disposal cancel live work and await compliant producers; a throwing teardown cancel force-fails only the record.
 - Owned-task access is fenced by the owner's session id. Ids are predictable, so authorization — not secrecy — is the boundary.
 - Settlement is first-wins: one terminal record, one round of contained listener notification, and released waiters, even against a late producer outcome.
-- start refuses work while no control surface is attached, so a producer cannot start work that callers cannot collect or stop.
+- 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.
 
 ```ts cordis-catalog
 /**
@@ -237,17 +237,19 @@ abstract kill(id: TaskId, caller?: Agent, reason?: string): 'requested' | 'alrea
 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.
  */
@@ -256,5 +258,5 @@ abstract attachSurface(name: string): () => void
 
 Types: [Agent](core.md)
 
-Source: [`packages/tasks/tasks/src/index.ts:50`](../../packages/tasks/tasks/src/index.ts)
+Source: [`packages/tasks/tasks/src/index.ts:55`](../../packages/tasks/tasks/src/index.ts)
 <!-- END GENERATED cordis-surface -->

docs/subsystems/tasks.zh.md

@@ -172,7 +172,7 @@ Implementations must honor these semantics:
 - Registrations outlive producer and control-surface fibers. Owner and service disposal cancel live work and await compliant producers; a throwing teardown cancel force-fails only the record.
 - Owned-task access is fenced by the owner's session id. Ids are predictable, so authorization — not secrecy — is the boundary.
 - Settlement is first-wins: one terminal record, one round of contained listener notification, and released waiters, even against a late producer outcome.
-- start refuses work while no control surface is attached, so a producer cannot start work that callers cannot collect or stop.
+- 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.
 
 ```ts cordis-catalog
 /**
@@ -237,17 +237,19 @@ abstract kill(id: TaskId, caller?: Agent, reason?: string): 'requested' | 'alrea
 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.
  */
@@ -256,5 +258,5 @@ abstract attachSurface(name: string): () => void
 
 Types: [Agent](core.md)
 
-Source: [`packages/tasks/tasks/src/index.ts:50`](../../packages/tasks/tasks/src/index.ts)
+Source: [`packages/tasks/tasks/src/index.ts:55`](../../packages/tasks/tasks/src/index.ts)
 <!-- END GENERATED cordis-surface -->