docs(rfc): propose nine simplification RFCs from a five-domain survey

Survey of master for surface area whose consumers are tests/docs only,
classified per candidate (production vs non-production corpus, rg + call-site
reads). New proposed/simplification RFCs:

- prune-producerless-vocabulary-variants: CacheHint/cache? fields,
  MessageSource 'agent', TurnTrigger 'continuation' (the TurnEndReasonMap
  omitted-until-emitted policy, applied)
- drop-inert-request-knobs: GenerateOptions.prefill (both adapters throw
  UNSUPPORTED), ToolSchema.strict (zero setters; beta-URL-only feature)
- drop-web-providers-change-event: the llm/adapter-change precedent replayed
- drop-image-content-block: no producer; every consumer silently drops it
- prune-write-only-fs-surface: fs-local STREAM_MIN_SIZE/streamMinSize,
  FsTarget.inputPath, FsEditOutcome.replacements/replaceAll,
  FileReadOutcome.limit/version
- prune-unimplemented-subagent-vocabulary: outputSchema/structured,
  toolFilter, sendMessage/resume (depthLimit stays)
- trim-acp-bridge-unreachable-surface: agentName/agentVersion knobs
  (resolves TODO(double-default)), toolKindFor name-sniffing
- prune-dead-core-spine-surface: SurfaceManager.invalidate(), runLoop/Inbox
  exports, ToolExecutionResult.callId
- share-app-bin-boot-glue: the twin coverage-exempt bin helpers

Also supplements three existing proposed RFCs with survey evidence: the bash
seam consumption census (generic-long-running-tool-runtime), three more
static inventories (discover-package-inventory), and the bridge's already-1:1
id usage (unify-agent-and-session-id).

docs/rfc/proposed/architecture/2026-06-20-generic-long-running-tool-runtime.md

@@ -22,6 +22,10 @@ The runtime should own:
 
 `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 (`packages/bash/tool-bash/src/index.ts`) consumes `resolve`, `run`, `start`, `ownerOf`, `readOutput`, `kill`, and `onTaskDone`. `get()`/`list()` and the per-task `BashTask.done` promise have test-harness consumers only — `get()`/`list()` were removed once and reverted on the merits (the implementation note in [prune dead methods from the persistence seam](../../implemented/simplification/2026-06-20-prune-dead-seam-methods.md) records the test-migration cost dwarfing the surface removed), and `done` doubles as `dsh-bash-local`'s dispose-to-quiescence primitive. The seam therefore carries two public completion representations — the per-task promise and the global `onTaskDone` listener registry — of which production consumes one: the runtime should pick exactly one public completion surface and record which. One shape wart for the split to dissolve: `BashExecSpec.timeoutMs` is required but ignored by `start()`, an artifact of sharing one spec type between foreground and background execution.
+
 ## Acceptance criteria
 
 - The bash-specific packages no longer define the generic task registry, owner-token authorization, polling, cancellation, or completion-notification machinery.