feat(tasks): background task runtime, generic task_* control tools, bash/subagent producers

One shared ctx.tasks registry (branded <kind>-N ids, owner-fenced
read/kill/wait/list, attachSurface misconfiguration fence, reported-flag
notice dedup, atomic register) + dsh-tool-tasks (task_output/task_list/
task_kill, completion-notice injection, background prompt habit).
Producers opt in via their own enableRunInBackground config: bash
(stream kind; seam slimmed to resolve/run/start returning a BashProcess
handle, bash_output/bash_kill deleted) and subagent (final-output kind;
done settles after run.dispose()). Owner disposal drains tasks through
the new awaited ctx.agents.onCleanup seam in the loop's disposal chain.
Both RFCs moved to implemented/; docs, catalogs, snapshots re-pinned.

docs/cordis-catalog/events.md

@@ -243,7 +243,7 @@ A subagent run settled — emitted when SubagentRun.result resolves (any stop re
 'subagent/end'(info: SubagentRunEndInfo): void
 ```
 
-Source: [`packages/subagent/subagent/src/index.ts:98`](../../packages/subagent/subagent/src/index.ts)
+Source: [`packages/subagent/subagent/src/index.ts:99`](../../packages/subagent/subagent/src/index.ts)
 
 ### `subagent/provider-added` — emit
 
@@ -253,7 +253,7 @@ A provider became resolvable in the SubagentService registry. Consumers that der
 'subagent/provider-added'(provider: SubagentProvider): void
 ```
 
-Source: [`packages/subagent/subagent/src/index.ts:72`](../../packages/subagent/subagent/src/index.ts)
+Source: [`packages/subagent/subagent/src/index.ts:73`](../../packages/subagent/subagent/src/index.ts)
 
 ### `subagent/provider-removed` — emit
 
@@ -263,7 +263,7 @@ A provider left the registry (its plugin's fiber was disposed — an unload or a
 'subagent/provider-removed'(name: string): void
 ```
 
-Source: [`packages/subagent/subagent/src/index.ts:83`](../../packages/subagent/subagent/src/index.ts)
+Source: [`packages/subagent/subagent/src/index.ts:84`](../../packages/subagent/subagent/src/index.ts)
 
 ### `subagent/start` — emit
 
@@ -273,7 +273,7 @@ A subagent run started — emitted after the provider is resolved and its capabi
 'subagent/start'(info: SubagentRunInfo): void
 ```
 
-Source: [`packages/subagent/subagent/src/index.ts:91`](../../packages/subagent/subagent/src/index.ts)
+Source: [`packages/subagent/subagent/src/index.ts:92`](../../packages/subagent/subagent/src/index.ts)
 
 ## `system-prompt/*`
 

docs/cordis-catalog/services.md

@@ -33,12 +33,14 @@ create(options: CreateAgentOptions): AgentHandle
 async resume(options: ResumeAgentOptions): Promise<AgentHandle>
 register(agent: Agent): () => void
 get(id: AgentId): Agent | undefined
+onCleanup(agentId: AgentId, cleanup: () => Promise<void>): () => void
+async drainCleanups(agentId: AgentId): Promise<void>
 list(): Agent[]
 ```
 
 Types: [Agent](../core-data-structures/core.md)
 
-Source: [`packages/core/agent/src/index.ts:117`](../../packages/core/agent/src/index.ts)
+Source: [`packages/core/agent/src/index.ts:124`](../../packages/core/agent/src/index.ts)
 
 ## `ctx.bash` — `BashExecutor` (abstract seam)
 
@@ -47,25 +49,19 @@ Abstract bash execution service. Subclass, implement the abstract methods, and l
 Semantics every implementation must honor:
 
 - run REJECTS only for infrastructure failures (unusable workdir, missing shell, pre-aborted signal). Nonzero exits, timeout kills, and abort kills RESOLVE with a descriptive BashRunResult — reporting a failed command is the tool layer's job, not an exception.
-- start returns immediately; no timeout applies to background tasks (callers stop them via kill or the spec's AbortSignal). Completion must fire the onTaskDone listeners exactly once per task, and must NOT fire after the service is disposed.
-- readOutput is incremental: consecutive reads never re-deliver output. Implementations bound their buffers; reads that lost data flag `lossy` and point at full-stream spill files when available.
-- Disposal kills every running task and awaits their exit (no orphan processes survive `fiber.dispose()`).
+- start returns immediately; no timeout applies to background processes (callers stop them via BashProcess.kill or the spec's AbortSignal). The handle's `done` settles at process close and never rejects (a spawn failure settles as `killed` with the error readable on stderr).
+- BashProcess.readOutput is incremental: consecutive reads never re-deliver output. Implementations bound their buffers; reads that lost data flag `lossy` and point at full-stream spill files when available.
+- Disposal kills every running background process and awaits their exit (no orphan processes survive `fiber.dispose()`).
 
 ```ts cordis-catalog
 abstract resolve(request: BashExecRequest): BashExecSpec
 abstract run(spec: BashExecSpec): Promise<BashRunResult>
-abstract start(spec: BashExecSpec): BashTask
-abstract get(id: BashTaskId): BashTask | undefined
-abstract ownerOf(id: BashTaskId): OwnerToken | undefined
-abstract list(): BashTask[]
-abstract readOutput(id: BashTaskId): BashTaskRead
-abstract kill(id: BashTaskId): boolean
-onTaskDone(listener: BashTaskListener): () => void
+abstract start(spec: BashExecSpec): BashProcess
 ```
 
-Types: [BashExecRequest](../core-data-structures/bash.md) · [BashExecSpec](../core-data-structures/bash.md) · [BashRunResult](../core-data-structures/bash.md) · [BashTask](../core-data-structures/bash.md) · [BashTaskRead](../core-data-structures/bash.md)
+Types: [BashExecRequest](../core-data-structures/bash.md) · [BashExecSpec](../core-data-structures/bash.md) · [BashRunResult](../core-data-structures/bash.md)
 
-Source: [`packages/bash/bash/src/index.ts:59`](../../packages/bash/bash/src/index.ts)
+Source: [`packages/bash/bash/src/index.ts:65`](../../packages/bash/bash/src/index.ts)
 
 ## `ctx.codeRuntime` — `CodeRuntime` (abstract seam)
 
@@ -196,7 +192,7 @@ list(): string[]
 start(name: string, request: SubagentStartRequest): SubagentRun
 ```
 
-Source: [`packages/subagent/subagent/src/index.ts:144`](../../packages/subagent/subagent/src/index.ts)
+Source: [`packages/subagent/subagent/src/index.ts:145`](../../packages/subagent/subagent/src/index.ts)
 
 ## `ctx.systemPrompt` — `SystemPrompt`
 
@@ -211,6 +207,25 @@ async assemble(context: AssembleContext = {}): Promise<PromptAssembly>
 
 Source: [`packages/core/system-prompt/src/index.ts:291`](../../packages/core/system-prompt/src/index.ts)
 
+## `ctx.tasks` — `TaskService`
+
+The `tasks` service: the runtime-global background task registry. See the module doc for the ownership, isolation, and lifecycle contracts.
+
+```ts cordis-catalog
+register(registration: TaskRegistration): TaskId
+list(caller?: Agent): TaskSnapshot[]
+get(id: TaskId, caller?: Agent): TaskSnapshot
+read(id: TaskId, caller?: Agent): TaskRead
+kill(id: TaskId, caller?: Agent, reason?: string): 'requested' | 'already-terminal'
+async wait(id: TaskId, timeoutMs: number, caller?: Agent, signal?: AbortSignal): Promise<TaskSnapshot>
+onTaskDone(listener: TaskDoneListener): () => void
+attachSurface(name: string): () => void
+```
+
+Types: [Agent](../core-data-structures/core.md)
+
+Source: [`packages/tasks/tasks/src/index.ts:84`](../../packages/tasks/tasks/src/index.ts)
+
 ## `ctx.tools` — `ToolRegistry`
 
 Tool registry (`ctx.tools`): tool plugins register definitions; the agent loop executes calls through the `tools/pre-execute` → dispatch → `tools/post-execute` pipeline. The registry contributes its schemas into the system-prompt assembly.