fix(agent): close _codex_session in AIAgent.close() to prevent subprocess leaks (#66671)

[kyssta-exe]

Summary

AIAgent.close() cleans up background processes, terminal sandboxes, browser daemons, child agents, HTTP clients, message history, and the SQLite session row — but never closes self._codex_session. This permanently orphans the Codex app-server subprocess tree (plus its MCP children) whenever a Codex-route session is closed via session.close or any other path that tears down the agent.

Fix

Add a guarded, idempotent _codex_session close step to AIAgent.close(), matching the existing crash-path cleanup in agent/codex_runtime.py. CodexAppServerSession.close() is already guarded by self._closed, so repeated calls are safe.

Testing

• All 40 existing Codex-related tests pass (5 persistence + 29 integration + 6 compaction).
• Verified syntax with python3 -c "import ast; ast.parse(...)".

Fixes #66671

[alt-glitch]

This was generated by AI during triage.

Related to #55450: this patch repairs only AIAgent.close(), while #55450 also covers release_clients() and interrupt retirement.

[tonydwb]

Code Review Summary

Verdict: Approved

Clean, well-scoped fix for a real subprocess leak. The change:

• Adds a guarded _codex_session close to AIAgent.close() (step 7, renumbers step 8)
• Uses getattr + None check matching existing defensive patterns
• CodexAppServerSession.close() is idempotent, so repeated calls are safe
• Preserves comment style and numbering of surrounding code

No issues found. LGTM.

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Reviewed by Hermes Agent

[teknium1]

Thanks for the focused lifecycle repair. The premise is confirmed on current main: run_agent.py:3603-3637 closes the HTTP client and continues teardown without closing _codex_session, while agent/codex_runtime.py:636-639 creates that session as AIAgent-owned state and agent/transports/codex_app_server.py:180-198 terminates its subprocess during close.

Problems

• This behavior change has no regression coverage. Existing retirement/crash tests in tests/run_agent/test_codex_app_server_integration.py:623-694 do not exercise ordinary AIAgent.close() teardown. Closed duplicate fix(agent): close _codex_session in AIAgent.close() to prevent Codex subprocess leak (#66671) #66865 includes focused tests for close-and-clear, missing-session, and repeated-close behavior.

Suggested changes

• Carry equivalent AIAgent.close() regression tests into this PR, asserting the Codex session is closed once, cleared, optional for non-Codex agents, and safe under repeated agent close calls.

Automated hermes-sweeper review.

[kyssta-exe]

Closing this PR because it has merge conflicts (mergeable=CONFLICTING). Please rebase on the latest main branch and resolve the conflicts before re-opening.