revert bash get()/list() removal — keep persistence-only prune

The original prune removed BashExecutor.get()/.list() too, but each is a
one-line accessor over the executor's already-tracked tasks map, and removing
them forced dsh-tool-bash's tests onto a ~35-line onTaskDone completion-tracking
harness just to replace the one-line ctx.bash.get(id) lookup. Per the AGENTS.md
"RFCs are proposals, not golden truth" principle, that disproportionate
migration cost is evidence the methods earn their keep — a test harness IS a
consumer programming against the seam.

Restore get()/list() (seam + LocalBashExecutor impl + the bash tests that used
them, dropping the doneFor/trackCompletions scaffolding). The persistence
has()/delete()/deleteStored removal stands — it had only contract-test callers
and no test-ergonomics cost. The RFC is retitled persistence-only with an
implementation note recording the bash revert.

packages/bash/bash/README.md

@@ -18,6 +18,7 @@ The split mirrors the LLM seam (`LlmService`/`LlmAdapter`) and the agent-tool su
 |---|---|
 | `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. |

packages/bash/bash/src/index.ts

@@ -85,6 +85,9 @@ export abstract class BashExecutor extends Service {
   /** Start a background task and return its handle immediately. */
   abstract start(spec: BashExecSpec): BashTask
 
+  /** Look up a background task by id. */
+  abstract get(id: string): BashTask | undefined
+
   /**
    * The opaque OWNER token recorded for a background task at {@link start}
    * (from the {@link BashExecSpec}'s `owner`), or `undefined` for an unknown id
@@ -100,6 +103,9 @@ export abstract class BashExecutor extends Service {
    */
   abstract ownerOf(id: string): string | undefined
 
+  /** All tracked background tasks (insertion order). */
+  abstract list(): BashTask[]
+
   /** Read output produced since the previous read. Throws for unknown ids. */
   abstract readOutput(id: string): BashTaskRead
 

packages/bash/bash/tests/service.spec.ts

@@ -44,10 +44,18 @@ class StubExecutor extends BashExecutor {
     return task
   }
 
+  get(id: string): BashTask | undefined {
+    return this.tasks.get(id)
+  }
+
   ownerOf(id: string): string | undefined {
     return this.owners.get(id)
   }
 
+  list(): BashTask[] {
+    return [...this.tasks.values()]
+  }
+
   readOutput(id: string): BashTaskRead {
     const task = this.tasks.get(id)
     if (!task) throw new Error(`unknown bash task "${id}"`)
@@ -80,6 +88,8 @@ describe('BashExecutor service seam', () => {
   it('registers as ctx.bash and serves the abstract API', async () => {
     const { bash } = await setup()
     const task = bash.start(bash.resolve({ command: 'sleep 1' }))
+    expect(bash.get(task.id)).toBe(task)
+    expect(bash.list()).toEqual([task])
     expect(bash.kill(task.id)).toBe(true)
     expect(bash.kill(task.id)).toBe(false)
     const result = await bash.run(bash.resolve({ command: 'true' }))