docs(agent-notes): consolidate subprocess decisions

.agents/notes/implemented/architecture/2026-07-26-subprocess-seam.md

@@ -12,8 +12,8 @@ English | [中文](2026-07-26-subprocess-seam.zh.md)
 
 A new `subprocess/` capability family owns "run and manage a process"; the bash family keeps "run a bash command" and consumes it:
 
-- **`@deepseek-ai/dsh-subprocess` (interface)** — the abstract `SubprocessService` owning `ctx.subprocess`: execution-world cwd and runtime storage, executable lookup, fully explicit ordinary spawns, and the terminal primitive added by the [portable execution-world decision](2026-07-28-portable-execution-world-consumers.md). Its vocabulary includes per-stream stdio dispositions, process and terminal handles, exit facts with deliberately no timeout/cancel classification, and the shared scrub plus `DSH_ENV_PREFIX`/`DshEnvironment`/`CollectedOutput` types. `argv` is never shell-interpreted.
-- **`@deepseek-ai/dsh-subprocess-local` (implementation)** — `LocalSubprocessService` over the former `run.ts` plumbing (`spawn.ts`) plus `node-pty`: detached groups, bounded collection and private spill files, executable lookup, private runtime storage, foreground/session inspection, credential scrub with explicit env merged after it, tree cleanup, and disposal that terminates and joins every managed process. It has no config; every limit arrives on the spec. Bash and PTY presentation environment overrides stay in their consumers.
+- **`@deepseek-ai/dsh-subprocess` (interface)** — the abstract `SubprocessService` owning `ctx.subprocess`: execution-world cwd and runtime storage, executable lookup, fully explicit ordinary spawns, and the terminal primitive added by the [portable execution-world decision](2026-07-28-portable-execution-world-consumers.md). Each stdio stream independently selects `'pipe'`, `'inherit'`, or bounded collection `{ maxBytes, spill? }`; stdin selects `'ignore'`, `'pipe'`, or `{ data }`. `SubprocessOutcome` carries exit facts with deliberately no timeout/cancel classification, while collected output remains on the handle after settlement. The seam also owns process and terminal handles, the shared scrub, and `DSH_ENV_PREFIX`/`DshEnvironment`/`CollectedOutput`; `argv` is never shell-interpreted.
+- **`@deepseek-ai/dsh-subprocess-local` (implementation)** — `LocalSubprocessService` over the former `run.ts` plumbing (`spawn.ts`) plus `node-pty`: detached groups, bounded collection and private spill files, executable lookup, private runtime storage, foreground/session inspection, and disposal that terminates and joins every managed process. `terminate()` owns TERM→grace→KILL for the tree, `waitForExit()` observes tree liveness, and injected `taskkill /T` covers Windows. Ordinary and terminal spawns apply the seam's case-insensitive `KEY`/`PASSWORD`/`SECRET`/`TOKEN` scrub before explicit env. The implementation has no config; every limit arrives on the spec, while Bash and PTY presentation environment overrides stay in their consumers.
 - **`dsh-bash-local` (consumer)** — `inject: ['subprocess']`; maps each resolved `BashExecSpec` onto a `SubprocessSpawnSpec` (`['bash', '-c', command]`), keeps its config, `resolve()` defaulting, fused-deadline `timedOut`/`aborted` classification, the `[stderr]`-marked background read merge with its consuming cursor, and the `onProcessDone` subclass hook. `dsh-bash-sandbox` is unchanged apart from redeclaring the inherited inject; it still wraps at the command-string level and re-enters the inherited spawn path.
 - **`dsh-bash` (seam)** — re-exports the moved vocabulary from `dsh-subprocess`, so no bash consumer changes an import; `BashExecRequest`/`BashExecSpec`/`BashProcess` and the sandbox facts remain bash-owned.
 
@@ -21,11 +21,17 @@ Every composition that loads a bash executor now also loads `@deepseek-ai/dsh-su
 
 Background-process lifetime moved from the executor to the subprocess service: the executor no longer retains a live-process set, so an executor reload leaves background work running and readable, and composition teardown (the service's disposal) remains the kill-and-join boundary. One behavioral seam shifted with it: a background spawn failure can no longer be buffered as fake stderr inside the plumbing (the service rejects `done` and buffers nothing for a process that never ran), so the executor injects the `spawn failed: …` note into exactly one `readOutput()` delta.
 
+Observed stream and lifecycle needs then moved the eligible process consumers onto the seam: LSP uses piped protocol streams plus a collected stderr tail; the ACP backend uses piped ndjson, inherited stderr, and a consumer-owned stdin-EOF disposal ladder; PTY uses `spawnTerminal()` while keeping readiness and terminal policy; Code Runtime uses ordinary raw pipes. `dsh-subagent-subprocess` and the private LSP tree helpers were deleted. MCP transport spawning, the SDK package-manager runner, synchronous TUI Git probing, and dependency-light test-support launchers remain outside by ownership or execution shape; their production callers share the scrub where applicable.
+
 ## Alternatives considered
 
 **Leave the process plumbing inside `dsh-bash-local` (status quo).** Rejected for the same reason the [task registry split](2026-07-26-task-registry-seam.md) landed: the boundary is stable and already documented in-code (`run.ts`'s module doc said "this layer reacts to an abort signal; the executor owns deadlines and classifies causes"), and keeping it private makes every future non-shell runner either fork the mechanics or depend on a bash-named package for non-bash work. The user-visible driver for this stack was exactly this split.
 
-**Migrate the repo's other spawn sites in the introducing change.** Rejected as scope creep with real design risk at that scale. The later [consumer-migration](2026-07-26-subprocess-consumer-migration.md) and [portable execution-world](2026-07-28-portable-execution-world-consumers.md) decisions reshape the interface around the observed LSP, subagent, PTY, and Code Runtime consumers; SDK and test-support launchers remain outside by ownership.
+**Keep the original batch-only interface and leave stream consumers bespoke.** Rejected after the observed LSP, ACP, PTY, and Code Runtime shapes showed that private process-tree signalling and environment scrubs would otherwise remain duplicated. The Node-shaped dispositions cover those consumers without buffering piped streams.
+
+**Use one `stdio: 'pipe' | 'inherit' | 'collect'` mode for all streams.** Rejected because real consumers mix modes per stream: LSP uses pipe/pipe/collect, ACP uses pipe/pipe/inherit, and Bash uses data/collect/collect.
+
+**Route every process launch through `ctx.subprocess`.** Rejected because the MCP SDK owns its transport spawn, the SDK wizard has no Cordis context and needs inherited redirection, the TUI probe is synchronous, and support launchers deliberately stay independent of product seams. PTY allocation did move behind `spawnTerminal()` because the provider, not the consumer, owns that substrate-specific primitive.
 
 **Put `run_in_background`/task semantics into the process seam instead.** Rejected: that boundary already exists — `ctx.tasks` owns ids, ownership, and notices, and the bash tool adapts a `BashProcess` into task hooks. The process seam sits *below* the bash executor, not beside the task registry.
 
@@ -33,6 +39,6 @@ Background-process lifetime moved from the executor to the subprocess service: t
 
 ## Consequences
 
-Bought: "run and manage a process" is a swappable capability used by Bash, LSP, PTY, Code Runtime, and ACP consumers; a containerized or remote process backend slots in without changing their domain semantics; the shared `DSH_*`/output vocabulary has a non-shell home; and background processes survive executor reloads, matching the task registry's lifetime model. Process and terminal plumbing is tested through `dsh-subprocess-local`; consumer suites pin only their owned behavior against the real service.
+Bought: "run and manage a process" is a swappable capability used by Bash, LSP, PTY, Code Runtime, and ACP consumers; a containerized or remote process backend slots in without changing their domain semantics; tree signalling, escalation, bounded collection, terminal mechanics, and credential scrubbing each have one implementation; and background processes survive executor reloads, matching the task registry's lifetime model. Process and terminal plumbing is tested through `dsh-subprocess-local`; consumer suites pin only their owned behavior against the real service.
 
-Cost: one more package pair and one more composition row everywhere a bash executor loads — a boot that loads an executor without the subprocess service leaves `ctx.bash` pending on `ctx.subprocess` (standard missing-service behavior). The moved-vocabulary re-exports keep `dsh-bash` imports working but mean two packages now name the same types; the subprocess seam is the owner and the bash seam documents the re-export. The spawn-failure note became single-delivery through the read path where the old plumbing retained it in the stderr buffer for repeated `readFrom(0)` reads — acceptable because the bash background read path was already a consuming cursor, and the note reaches the one reader that exists.
+Cost: one more package pair and one more composition row wherever a consumer loads; a missing subprocess provider leaves the consumer pending by standard service-injection behavior. Every backend implements execution-world coordinates, executable lookup, three stdio modes, tree lifecycle, and one terminal primitive. The moved-vocabulary re-exports keep `dsh-bash` imports working but mean two packages name the same types; the subprocess seam is the owner. The spawn-failure note became single-delivery through Bash's consuming read cursor instead of repeatable stderr-buffer content.