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.

packages/bash/bash/README.md

@@ -1,6 +1,6 @@
 # @deepseek-ai/dsh-bash
 
-The **bash executor seam**: an abstract `BashExecutor` service (`ctx.bash`) defining WHAT a bash backend does — run commands, manage background tasks — without saying HOW.
+The **bash executor seam**: an abstract `BashExecutor` service (`ctx.bash`) defining WHAT a bash backend does — run foreground commands, start background processes — without saying HOW.
 
 This package is one third of the bash capability, split so each concern can evolve (and be swapped) independently:
 
@@ -8,7 +8,7 @@ This package is one third of the bash capability, split so each concern can evol
 |---|---|
 | `@deepseek-ai/dsh-bash` (this) | the interface: abstract service + vocabulary types |
 | `@deepseek-ai/dsh-bash-local` | an implementation: local subprocesses |
-| `@deepseek-ai/dsh-tool-bash` | the model-facing tool schemas over `ctx.bash` |
+| `@deepseek-ai/dsh-tool-bash` | the model-facing tool schema over `ctx.bash` |
 
 The split mirrors the LLM seam (`LlmService`/`LlmAdapter`) and the agent-tool survey: pi hides execution behind a `BashOperations` interface (local shell / SSH / VM backends), Codex behind an exec-server protocol. A future sandboxed, containerized, or remote executor implements this interface and the tool schemas don't change.
 
@@ -16,18 +16,14 @@ The split mirrors the LLM seam (`LlmService`/`LlmAdapter`) and the agent-tool su
 
 | Member | Semantics |
 |---|---|
+| `resolve(request)` | Fill a caller's `BashExecRequest` (optional `workdir`/`timeoutMs`) into a fully-resolved `BashExecSpec` from the implementation's config defaults and caps — the explicit defaulting step consumers call before `run`/`start`. |
 | `run(spec)` | Foreground execution. Resolves when the command finishes. **Rejects only for infrastructure failures** (unusable workdir, missing shell, pre-aborted signal); nonzero exits, timeout kills, and abort kills resolve with a descriptive `BashRunResult`. |
-| `start(spec)` | Background execution. Returns a `BashTask` handle immediately; **no timeout applies** (stop tasks via `kill`). |
-| `get(id)` / `list()` | Task lookup. |
-| `ownerOf(id)` | The opaque OWNER token recorded for a background task at `start` (from the spec's `owner`), or `undefined` for an unknown id OR a known-but-ownerless task. The executor stores/returns it verbatim and NEVER interprets it — the access POLICY lives in the consumer (`dsh-tool-bash`), which compares `ownerOf(id)` to the caller's token. Storing ownership here (disposed with the executor's fiber) is what makes it survive a consumer HMR reload. |
-| `readOutput(id)` | **Incremental** output read — consecutive reads never re-deliver. Reads that lost data to buffer bounds flag `lossy` and point at full-stream spill files. Throws for unknown ids. |
-| `kill(id)` | Kill a running task. Returns `false` when it already finished; throws for unknown ids. |
-| `onTaskDone(listener)` | Completion listener (effect-based, disposer returned). Fires exactly once per task; never after the service is disposed. |
+| `start(spec)` | Background execution. Returns a `BashProcess` handle immediately; **no timeout applies** (stop the process via the handle's `kill()` or the spec's AbortSignal). |
 
-Implementations subclass `BashExecutor`, implement the abstract methods, and call `notifyTaskDone(task)` on background completion. Disposal must kill every running task (no orphan processes) — see the HMR-safety tests.
+The seam is deliberately TASK-FREE: `start()` hands back only the `BashProcess` handle — `command`, `status`, `exitCode`/`signal`, a never-rejecting `done` quiescence promise, a consuming incremental `readOutput()` (reads that lost data to buffer bounds flag `lossy` and point at full-stream spill files; reads stay valid after exit), and an idempotent `kill()`. Task ids, cross-session isolation, polling tools, and completion notices are the generic [`ctx.tasks` runtime](../../tasks/tasks/README.md)'s job — the tool layer adapts the handle into a task registration — which keeps a remote/sandbox executor free of any session or registry dependency. Disposal must kill every running background process and await its exit (no orphan processes) — see the HMR-safety tests.
 
 ## Vocabulary
 
-`BashExecRequest` (command, workdir?, timeoutMs?, signal?, stdin?, env?, owner?) resolves to `BashExecSpec` (command, workdir, timeoutMs, signal?, stdin?, env?, owner) before execution; `owner` is optional on the request and **required-but-nullable** (`OwnerToken | undefined`) on the resolved spec, so a forgotten owner is a visible `undefined` rather than a silently-absent property. The task id (`BashTaskId`) and the `owner` token (`OwnerToken`) are [branded](../../util/brand) — `OwnerToken` is a DISTINCT brand from `SessionId` (the seam never imports `dsh-session`; the `dsh-tool-bash` consumer is the single boundary that casts its `SessionId` into one). `run()` returns `BashRunResult` (exitCode, signal, timedOut, aborted, timeoutMs, stdout/stderr as `CollectedOutput`) and `start()`/`readOutput()` use `BashTask`/`BashTaskRead` for the background side. See `src/types.ts` for the full contracts.
+`BashExecRequest` (command, workdir?, timeoutMs?, signal?, stdin?, env?) resolves to `BashExecSpec` (command, workdir, timeoutMs, signal?, stdin?, env?) before execution. `run()` returns `BashRunResult` (exitCode, signal, timedOut, aborted, timeoutMs, stdout/stderr as `CollectedOutput`) and `start()` returns `BashProcess`, whose `readOutput()` yields a `BashProcessRead`. See `src/types.ts` for the full contracts.
 
-`stdin` and `env` are set by in-process plugins (the hooks bridges, native plugins) to feed a hook command its JSON payload on stdin and its `CLAUDE_PROJECT_DIR`/`CLAUDE_PLUGIN_ROOT` env. The model-facing `dsh-tool-bash` tool does not expose them as parameters — a model already has equivalent power through shell syntax (`FOO=bar cmd`, a heredoc), so they would be redundant tool params. This is not a security boundary: the implementation's credential scrub (not these fields) is what keeps the harness's ambient secrets out of a spawned command. They are plain optionals on the resolved spec (unlike `owner`'s required-but-nullable): a missing one means "none", the safe default. See [the bash-stdin-env RFC](../../../docs/rfc/implemented/architecture/2026-06-30-bash-stdin-env-trusted-plugin-surface.md).
+`stdin` and `env` are set by in-process plugins (the hooks bridges, native plugins) to feed a hook command its JSON payload on stdin and its `CLAUDE_PROJECT_DIR`/`CLAUDE_PLUGIN_ROOT` env. The model-facing `dsh-tool-bash` tool does not expose them as parameters — a model already has equivalent power through shell syntax (`FOO=bar cmd`, a heredoc), so they would be redundant tool params. This is not a security boundary: the implementation's credential scrub (not these fields) is what keeps the harness's ambient secrets out of a spawned command. They are plain optionals on the resolved spec: a missing one means "none", the safe default. See [the bash-stdin-env RFC](../../../docs/rfc/implemented/architecture/2026-06-30-bash-stdin-env-trusted-plugin-surface.md).