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Tianyi Cui 9ebc38badf docs(rfc): revise the batch for the hooks-stack base; add three post-stack RFCs

The branch now bases on the hooks stack (PR #138's head), so every
'in-flight' reference to stack content became a current-state fact.
Audited all nine RFCs + three supplements claim-by-claim against the
merged tree (none invalidated; several strengthened):

- prune-dead-core-spine-surface: describe the landed tools/pre-execute →
  dispatch → tools/post-execute pipeline — listeners return Decisions,
  the registry builds every result and snapshots it to protect callId,
  and a second (mutation-guard) test pins the field; drop the resolved
  wait-for-interception hedge; scope the additionalContext ferry out.
- prune-producerless-vocabulary-variants: the ui-stdio fixture migrated
  off the continuation trigger (llm-replay is the sole writer now); the
  stack's own additions (rejected, prompt/blocked, hook/invoked+result)
  all arrived with producers — the admission policy demonstrated live.
- prune-unimplemented-subagent-vocabulary: enrichment landed as
  lastAssistantMessage only (agentType was dropped in the stack's own
  review — the same judgment this RFC extends); the seam RFC now names
  tools/pre-execute deny, which exists, sharpening the re-add path.
- drop-inert-request-knobs / drop-image-content-block /
  trim-acp-bridge-unreachable-surface: current-state rewordings (shipped
  bridges set no request fields; only compact-basic has explicit image
  arms; 13 hook goldens also pin agentInfo).
- generic-long-running-tool-runtime census: second production seam
  consumer (hook-protocol runHook: resolve+run, stdin/env, foreground
  only — background machinery stays single-consumer); scrub-duplication
  blast radius.
- discover-package-inventory: identical 54-entry tsconfig reference
  sets; the comparesLog scenario knob (fixture-derivable, like recorded).
- unify-agent-and-session-id: third divergence site (in-process subagent
  children mint two UUIDs), the hooks bridge id-lookups, and ui-stdio's
  labelBySession map as a consumer that deletes under unification.

New RFCs from the post-stack survey:
- remove-agent-steering-mirror: the last mirror-of-durable event; zero
  production listeners; both retention RFCs deferred its fate, and the
  'no durable twin' rationale is contradicted by the adjacent append.
- tighten-hook-protocol-contract: producer-less 'native' dialect,
  parsed-and-discarded suppressOutput, and hook/result semantics
  (truncation + decision-string) defined twice in the bridges instead
  of the lib that owns the event.
- single-source-acp-replay-config: cordis.yml/cordis.snapshot.yml differ
  by exactly one plugin entry, with no gate on the forced symmetry.

2026-07-04 11:24:44 +08:00

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RFC: Extract a generic long-running tool runtime

Status: proposed

Problem

The bash capability seam supports both foreground commands and long-running background tasks. Background support is large: the abstract executor exposes start, get, ownerOf, list, readOutput, kill, and onTaskDone; the local executor tracks tasks, incremental reads, owner tokens, process cleanup, and completion listeners; the model sees three tools (bash, bash_output, bash_kill); the tool plugin injects completion notices back into the owning agent's session. The local executor fences task access behind owner tokens because predictable global task ids are a cross-session read/kill hazard.

The tool cookbook already points at the real design smell: background bash is really generic long-running-tool infrastructure living inside one tool. If future tools need background execution, polling, kill, ownership, and completion notices, those semantics should not be hidden in dsh-bash.

Proposal

Move long-running task semantics above bash into a tool-agnostic runtime. Bash remains able to run background commands, but it stops owning the general concepts of task ids, ownership tokens, polling, cancellation, completion notifications, and model-facing "read/kill this task" commands.

The runtime should own:

Stable task ids and owner tokens keyed to the calling session/agent.
Registration of a long-running task with a producer for incremental output and a completion promise.
Generic read/cancel/list operations with the same cross-session authorization rule for every tool.
Completion notification injection into the owning session.
Presentation hooks for pending/running/completed task state, with bash supplying only command-specific labels and output formatting.

dsh-bash then keeps the bash-specific execution contract: resolve a request into a command spec, run a foreground command, or start a process and hand its streams/process handle to the generic runtime. dsh-tool-bash keeps the model-facing command tool, but the follow-up operations become generic long-running-tool operations or a shared utility that bash registers with, rather than bespoke bash_output/bash_kill plumbing.

Current seam consumption

A consumer census of the surface the runtime would carve up. Production has two seam consumers: packages/bash/tool-bash/src/index.ts consumes resolve, run, start, ownerOf, readOutput, kill, and onTaskDone; and the hook bridges — via dsh-hook-protocol's runHook (packages/hooks/hook-protocol/src/runner.ts) — consume resolve + run only, a foreground-only trusted-plugin caller that sets the seam's stdin/env fields, so the background machinery stays single-consumer (which sharpens the extraction premise). get()/list() have test-harness consumers only — they were removed once and reverted on the merits (the implementation note in prune dead methods from the persistence seam records the test-migration cost dwarfing the surface removed). The per-task BashTask.done promise has no consumer through the public seam either (dsh-tool-bash completes via onTaskDone), but it is production-load-bearing INSIDE the implementation: dsh-bash-local's disposal awaits it to reach quiescence. The seam therefore exposes two public completion representations — the per-task promise and the global onTaskDone listener registry — and the shipped consumers use only the latter: the runtime should pick exactly one public completion surface and record which. Two shape facts for the split to dissolve or preserve deliberately: BashExecSpec.timeoutMs is required but ignored by start() (documented in the seam JSDoc itself), and stdin/env ride the shared spec for the foreground trusted-plugin path — the carve-up must keep a plain in-process foreground resolve+run path carrying them, so hook execution is never forced through the long-running runtime. Adjacent blast radius: the credential scrub is duplicated between the two production spawn sites (packages/bash/bash-local/src/run.ts and packages/subagent/subagent-acp/src/run.ts); if the runtime absorbs spawn-env policy, collapsing that duplication is its work too.

Acceptance criteria

The bash-specific packages no longer define the generic task registry, owner-token authorization, polling, cancellation, or completion-notification machinery.
A shared long-running-task service or tool layer owns those semantics and is documented as the path for any future background-capable tool.
Bash background behavior remains available through the shared layer, with tests proving cross-session isolation still holds.
ACP and snapshot fixtures render background bash through the shared task vocabulary, not through bash-only lifecycle semantics.
The tool cookbook points long-running tools at the shared runtime instead of telling each tool to invent its own task protocol.

What we give up

The bash package loses local ownership of an already-working background-task implementation, and the implementing PR may temporarily churn model-facing tool names or transcript presentation. That churn is worthwhile if it leaves one background-task contract instead of making every future long-running tool clone bash's private protocol.

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