fix: tear down session interactions and background processes on close - #711

## Summary

Follow up #711 with a publication fence for closed sessions on ACP v1
and v2.

- Suppress late session updates and reject new session interactions
after teardown, including registered child views and direct v2
state/replay paths. Ordinary request responses are not filtered.
- Preserve an inserted prompt's successful response even if it follows
the close response, while sending the final idle/cancelled state before
close responds.
- Track URL elicitation scope in shared client delivery. Suppress
completions for closed-session, declined, duplicate and unknown flows,
including after the same session ID resumes. Request-scoped login
completion remains independent of session close.
- Discard queued publication from disposed v2 foreground states and
prevent late closed-state calls from recreating state that could
contaminate a later resume.
- Reopen root delivery when session state is installed and child
delivery after a fresh announcement.
- Preserve AIR archive's final metadata update inside the existing outer
close fence. The operation finishes its required update before
publication closes, rather than adding an exception to the post-close
rule.
- Do not infer session scope from arbitrary custom-extension payloads.

## Validation

- `npm run typecheck` — passed, including examples.
- `npm test` — 2,293 passed, 39 skipped.
- `npm run test:integration` — all 19 passed across 8 files.
- `npm run build` and `git diff --check` — passed.
- Final focused delivery/foreground/wire regression run — 27 passed.
- 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.

Wire regression coverage includes v1/v2, standard and AIR child views,
close/delete, resume, direct v2 sends, URL completion, and a
deliberately delayed inserted-prompt response. Existing
notification-order snapshots are unchanged.

## Remaining follow-ups

Resume snapshots and metadata resynchronization, setup-response
ordering, configuration publication, subagent directories, and
authentication/MCP delegation remain separate changes. Active-resume
environment replacement still needs the protocol decision about
in-flight operations using removed roots or MCP servers. No internal
review document 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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