fix: update ACP SDK to 2.2 and align protocol behavior - #710

…#711)

## Summary

Follow up #710 with the session-close interaction and background-process
cleanup changes from the protocol review. Applies to ACP v1 and v2;
`session/delete` uses the same teardown path.

- Give session-scoped permission requests and elicitations a shared
cancellation owner, including idle/background interactions and
registered child sessions. Preserve caller cancellation and leave
request-scoped login interactions alone.
- Cancel pending interactions before waiting for runtime teardown and
reject new interactions while the owning session is closing.
- Stop Codex background processes before unsubscribe and before
responding to close, independently of AIR async-task display support.
Codex's unsubscribe only detaches the subscriber; delayed unload is not
a cleanup barrier.
- Share background-terminal pagination with the existing task tracker.
Read every page before terminating processes, and detect repeated
cursors.
- Clean up child processes only for ownership established by native
events/readbacks. Do not wait on unrelated metadata reads during close
or act on foreign ownership.
- Preserve the local session and subscriptions when process cleanup
fails, so close can be retried. A false termination result is checked
against the current process list rather than assumed to mean success.
- Make already-closed/unknown close requests succeed without unnecessary
Codex calls, and publish terminal task state only after successful
cleanup.

## Validation

- `npm run typecheck` — passed, including examples.
- `npm test` — 2,282 passed, 39 skipped.
- `npm run test:integration` — all 19 tests passed across 8 files.
- `npm run build` and `git diff --check` — passed.
- A new real-Codex integration test starts a long-lived shell process,
confirms it is alive, closes the session without AIR async-task support,
and confirms the OS process has exited when close responds.
- Real Codex smoke: `npm run codex-test -- -p "Reply with exactly OK. Do
not use tools or modify any files." -o summary` — completed with
`end_turn`.
- Opt-in E2E suite was not run.

## Remaining follow-ups

This is not a claim of complete v2 lifecycle conformance. The general
post-close notification fence, resume snapshots/metadata, setup response
ordering, and active-resume environment replacement remain separate
changes. Active-resume replacement also needs the spec decision about
in-flight operations using removed roots or MCP servers. No internal
review Markdown file is included.

🤖 I have created a release *beep* *boop*
---


##
[2.6.0](v2.5.0...v2.6.0)
(2026-11-06)


### Features

* expose configured permission profiles as modes
([#395](#395))
([caf2e87](caf2e87))
* predict the follow-up prompt with thread/sample on the session thread
([#740](#740))
([f9cb470](f9cb470))
* show async Codex questions as elicitations
([#707](#707))
([cc57c7e](cc57c7e))
* update ACP SDK to 2.4 and align protocol behavior
([#727](#727))
([ab513aa](ab513aa))


### Bug Fixes

* clear stale entity metadata during ACP v2 replay
([#716](#716))
([580d8b9](580d8b9))
* defer startup interactions until session setup is delivered
([#714](#714))
([ad993bb](ad993bb))
* fence turn interrupt retries to the original prompt
([#723](#723))
([9c33f86](9c33f86))
* match vendor-prefixed gateway model ids such as OpenRouter's
([#731](#731))
([29195ec](29195ec))
* preserve sibling session metadata namespace fields
([#718](#718))
([3720341](3720341))
* publish complete configuration updates for session changes
([#715](#715))
([b7ac0bf](b7ac0bf))
* release the prompt suggestion thread and keep it minimal
([#709](#709))
([82ad58f](82ad58f))
* report verified standard subagent directories
([#722](#722))
([7d7e95a](7d7e95a))
* resynchronize current session metadata on ACP v2 resume
([#717](#717))
([927c480](927c480))
* scope authentication cancellation and initial status delivery
([#720](#720))
([e059ab7](e059ab7))
* show commands in Zed approval prompts
([#735](#735))
([cca2dca](cca2dca))
* skip the app-server restart when providers/set repeats the applied
config
([#728](#728))
([3b35338](3b35338))
* start the Codex app-server with the provider of the gateway routing
([#733](#733))
([cbcd446](cbcd446))
* suppress session messages after close
([#712](#712))
([85bf932](85bf932))
* synchronize resumed titles and reset replayed message metadata
([#713](#713))
([ef45a6d](ef45a6d))
* tear down session interactions and background processes on close
([#711](#711))
([1e89efa](1e89efa))
* update ACP SDK to 2.2 and align protocol behavior
([#710](#710))
([6f96fbe](6f96fbe))
* update codex to 0.166.0
([#734](#734))
([e53f23e](e53f23e))

---
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Co-authored-by: acp-release-bot[bot] <246668977+acp-release-bot[bot]@users.noreply.github.com>

Upstream v2.6.0 adds an initialize-v2 test next to the downstream one (repeated initialize without
reinitializing Codex), which conflicted only by position. Both tests are kept; every added and
removed line of the patch is unchanged. Upstream's agentclientprotocol#710 path style for GitPatch (native absolute
paths for ACP v2, Git-relative paths by default) leaves the ACP v1 wrapper unchanged: the
client-neutral _meta.diffPatch still gets the same Git-relative patch as the AIR extension.
Adapted from 4ab2596.