Review direction (tianyicui, PR #660): in a stacked PR, change all other
process-running places to use the new service.
- lsp-local: LspConnection spawns through ctx.subprocess (piped protocol
streams + a no-spill collected stderr tail); its private process-tree
helpers (POSIX group signalling, Windows taskkill, liveness polling) are
deleted in favor of the seam's handle verbs, and its buildChildEnv now
rides scrubbedParentEnv (LSP children also stop inheriting stale DSH_*).
The plugin injects 'subprocess'; compositions/tests mount
dsh-subprocess-local.
- subagent-acp: the ACP child spawns through the seam (piped ndjson streams,
inherited stderr); spawn failure surfaces through done-rejection into the
same startup race; disposal is handle.dispose with the plugin's configured
graces. dsh-subagent-subprocess is DELETED — its dispose ladder and scrub
are the seam's, and the isolated-config-dir helper had no consumer.
- mcp-client, pty-local, sdk-helper: adopt scrubbedParentEnv as the one
scrub definition (their spawns stay put by ownership: the MCP SDK and
node-pty own those calls; the SDK wizard runs outside any composition).
- Coverage: per-file 100% over every touched src file, with each v8 ignore
carrying a platform or contract reason; new suites cover stdio
dispositions, the dispose ladder tiers, injected-win32 tree semantics,
waitForExit, settled-kill/terminate no-ops, and spawn-failure disposal.
- Docs: consumer-migration Agent Note (en; zh follows in this PR), seam note
updated in place, subprocess.md rewritten for the reshaped vocabulary
(type-equiv re-registered), READMEs and SERVICE_ROLES updated, taskkill
added to knip ignoreBinaries.