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

.agents/notes/implemented/architecture/2026-07-26-task-registry-seam.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 .agents/notes/implemented/architecture/2026-07-26-task-registry-seam.md
-2026-07-26-task-registry-seam.md: 45801505f1729ec6094900acf94b4c17ed92c3b1
-2026-07-26-task-registry-seam.zh.md: 8dd90b34d2da1d22caba13fe8c388dab4a29be0d
+2026-07-26-task-registry-seam.md: 4487bd9c53595fa8b4eed588b294ceafe3ab58dc
+2026-07-26-task-registry-seam.zh.md: 6195dc809e84852c7e0f63ac101ba0ed6a46853e

.agents/notes/implemented/architecture/2026-07-26-task-registry-seam.md

@@ -12,7 +12,7 @@ The [background-task runtime](2026-06-20-generic-long-running-tool-runtime.md) s
 
 `tasks/` is now a three-package capability family in the bash-trio shape:
 
-- **`@deepseek-ai/dsh-tasks` (Service Definition)** — the abstract `TaskService extends Service` owning `ctx.tasks`, the eight-method contract (`start`, `list`, `get`, `read`, `kill`, `wait`, `onTaskDone`, `attachSurface`), all vocabulary types (`TaskId`, `TaskKindMap`, `TaskStart`, `TaskHooks`, `TaskOutcome`, `TaskSnapshot`, `TaskRead`, `TaskDoneListener`), and the snapshot invariant companion. The class-level JSDoc states the semantics every Service provider owes: registrations outlive producer and surface fibers, owned access is session-fenced, settlement is first-wins with contained listeners, and `start` refuses work while no control surface is attached.
+- **`@deepseek-ai/dsh-tasks` (Service Definition)** — the abstract `TaskService extends Service` owning `ctx.tasks`, the eight-method contract (`start`, `list`, `get`, `read`, `kill`, `wait`, `onTaskDone`, `attachSurface`), all vocabulary types (`TaskId`, `TaskKindMap`, `TaskStart`, `TaskHooks`, `TaskOutcome`, `TaskSnapshot`, `TaskRead`, `TaskDoneListener`), and the snapshot invariant companion. The class-level JSDoc states the semantics every Service provider owes: registrations outlive producer and surface fibers, owned access is session-fenced, settlement is first-wins with contained listeners, and `start` refuses work while no attached control surface serves the spec's owner (surfaces and listeners are scope-layered, so one process-wide registry answers both questions per owner).
 - **`@deepseek-ai/dsh-tasks-local` (Service provider)** — `LocalTaskService`, the process-local registry moved verbatim: the in-memory store, per-kind counters, waiter bookkeeping, `TASK_WAIT_TIMEOUT` deadline code, owner-cleanup effects, and force-fail teardown. The `dsh-timeout` dependency moves here with it; the Service Definition package has no provider dependencies.
 - **`@deepseek-ai/dsh-tool-tasks` (Consumer)** — unchanged; it injects `'tasks'` and never imports provider types.
 

.agents/notes/implemented/architecture/2026-07-26-task-registry-seam.zh.md

@@ -12,7 +12,7 @@ Status: implemented
 
 `tasks/` 如今是一个 bash 三件套形态的三包能力家族：
 
-- **`@deepseek-ai/dsh-tasks`（Service Definition）**——抽象的 `TaskService extends Service`，拥有 `ctx.tasks`、八个方法的约定（`start`、`list`、`get`、`read`、`kill`、`wait`、`onTaskDone`、`attachSurface`）、全部词汇类型（`TaskId`、`TaskKindMap`、`TaskStart`、`TaskHooks`、`TaskOutcome`、`TaskSnapshot`、`TaskRead`、`TaskDoneListener`），以及快照不变式配套插件。类级 JSDoc 陈述了每个 Service provider 都必须兑现的语义：注册的存续期长于生产方与控制接口的 fiber，有所有者的访问以会话为界，结算遵循首次结果优先且监听器错误被隔离，并且在没有附加任何控制接口时 `start` 拒绝启动工作。
+- **`@deepseek-ai/dsh-tasks`（Service Definition）**——抽象的 `TaskService extends Service`，拥有 `ctx.tasks`、八个方法的约定（`start`、`list`、`get`、`read`、`kill`、`wait`、`onTaskDone`、`attachSurface`）、全部词汇类型（`TaskId`、`TaskKindMap`、`TaskStart`、`TaskHooks`、`TaskOutcome`、`TaskSnapshot`、`TaskRead`、`TaskDoneListener`），以及快照不变式配套插件。类级 JSDoc 陈述了每个 Service provider 都必须兑现的语义：注册的存续期长于生产方与控制接口的 fiber，有所有者的访问以会话为界，结算遵循首次结果优先且监听器错误被隔离，并且当没有任何已附加的控制接口服务于 spec 的所有者时 `start` 拒绝启动工作（控制接口与监听器按 scope 分层，因此一个进程级注册表能逐所有者地回答这两个问题）。
 - **`@deepseek-ai/dsh-tasks-local`（Service provider）**——`LocalTaskService`，即原样迁移的进程内注册表：内存存储、按 kind 划分的计数器、等待方簿记、`TASK_WAIT_TIMEOUT` deadline 代码、所有者清理 effect，以及强制失败的拆除。`dsh-timeout` 依赖随之迁入此包；Service Definition 包不含任何提供方依赖。
 - **`@deepseek-ai/dsh-tool-tasks`（Consumer）**——保持不变；它注入 `'tasks'`，从不导入提供方类型。