Handle session/setTitle and emit SessionInfoUpdate

[daniel-agentee]

Summary

Implements the agent side of the new ACP session/setTitle method so ACP clients (e.g. Zed) can persist a session rename through codex-acp. After a successful rename, codex-acp emits a SessionInfoUpdate notification so the client can repaint its session list inline — no restart, no session/list round-trip required.

Why

Zed's agent panel already has a title editor for ACP sessions (zed#54689), but it can't persist anything for ACP threads because there was no protocol method to push the new title down. With the protocol method now defined upstream, codex-acp needs a handler that:

1. Updates the SQLite state index (so session/list returns the new title even after a fresh process)
2. Writes a custom-title entry to the JSONL rollout (so find_thread_name_by_id returns the new value)
3. Notifies the client so the title in the sidebar updates immediately

session/list also needs to consult the rollout's custom-title entries when assembling each session's title, otherwise the rename is invisible until the next codex restart.

What's in this PR

• codex_agent.rs — registers a SetSessionTitleRequest handler. For loaded sessions it dispatches to Thread::set_title; for historical/listed sessions that are not currently loaded, it updates the SQLite/index state directly and emits the same SessionInfoUpdate notification.
• listSessions now consults find_thread_name_by_id first and falls back to the formatted first user message.
• thread.rs — adds Thread::set_title + ThreadMessage::SetTitle + ThreadActor::handle_set_title, which calls append_thread_name(codex_home, thread_id, title) to persist the rename. Then emits SessionUpdate::SessionInfoUpdate { title } so the client knows.
• New unit coverage for both paths:
  • test_set_session_title_renames_underlying_thread covers the loaded-thread actor path, JSONL persistence, and SessionInfoUpdate emit.
  • set_session_title_persists_unloaded_session covers renaming a listed/historical session that is not present in the live sessions map.

Tests

cargo fmt --all -- --check
cargo clippy --all-targets --all-features -- -D warnings
cargo check --locked
cargo build --locked
cargo test --locked --lib
bash npm/testing/validate.sh
node npm/testing/test-platform-detection.js

23 lib tests pass on the rebased branch (269c0d3).

Upstream dependency chain

This PR sits on top of two upstream PRs that must merge first. To keep the build green here in the meantime, Cargo.toml carries a temporary [patch.crates-io] block pointing at branch revs on my fork — see the inline comment in Cargo.toml for removal steps once releases ship.

1. Schema — agentclientprotocol/agent-client-protocol#1199 adds SetSessionTitleRequest / SetSessionTitleResponse to the protocol schema. Patched in here via agent-client-protocol-schema = { git = ..., rev = b9739d6 }.
2. Rust SDK routing — agentclientprotocol/rust-sdk#164 wires the new schema types into the agent-side dispatch tables. Patched in here via agent-client-protocol = { git = ..., rev = 34523b3 }.
3. This PR — uses the new types to handle the request and emit the repaint notification.

Once #1199 and rust-sdk#164 merge and an agent-client-protocol release ships with session/setTitle, drop the temporary patch entries and bump agent-client-protocol to the released version.

Companion PRs

• Follow-up: #287 adds /rename as a builtin slash command, on top of Expose Codex skills as ACP slash commands #279 + this PR — keeping rename infrastructure and the inline slash command as separate reviewable concerns.

Draft

Drafted while waiting on the two upstream PRs above. Ready for design review on the codex-acp side; will mark ready-for-review once the dependency chain unblocks the temp patch removal.

[chatgpt-codex-connector]

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Reviewed commit: df61470c54

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[chatgpt-codex-connector]

Replace local path override with a resolvable dependency

Avoid committing agent-client-protocol as a local path dependency here, because path = "../rust-sdk/src/agent-client-protocol" requires a sibling checkout that is not part of this repository. In a normal clone (including CI and downstream builds), Cargo cannot resolve that path, so cargo build --locked fails before compilation. This effectively makes the commit non-buildable outside the author’s local workspace.

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[daniel-agentee]

Thanks @chatgpt-codex-connector — addressed in 24ce239.

Replaced the path = "../rust-sdk/..." override with a proper [patch.crates-io] block at the bottom of Cargo.toml. The [dependencies] line for agent-client-protocol is now identical to main (just version = "=0.11.1"); the override lives in a clearly-marked temporary block that cleans up to a single deletion + version bump once the two upstream PRs in the chain release (linked in the PR description).

cargo build --locked and cargo test --locked --lib are now green from a fresh clone.

[chatgpt-codex-connector]

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[chatgpt-codex-connector]

💡 Codex Review

Here are some automated review suggestions for this pull request.

Reviewed commit: 24ce239c69

ℹ️ About Codex in GitHub

Your team has set up Codex to review pull requests in this repo. Reviews are triggered when you

• Open a pull request for review
• Mark a draft as ready
• Comment "@codex review".

If Codex has suggestions, it will comment; otherwise it will react with 👍.

Codex can also answer questions or update the PR. Try commenting "@codex address that feedback".

[chatgpt-codex-connector]

Support renaming sessions that are not currently loaded

session/setTitle now fails fast on self.get_thread(&args.session_id), which only resolves sessions in the in-memory self.sessions map. After session/close (or before session/load), a session can still appear in session/list but is no longer in that map, so rename requests for listed historical sessions return resource_not_found instead of persisting the new title. This breaks the main rename flow for non-active sessions; the handler should allow a DB/index-only rename path when no live thread is attached.

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[daniel-agentee]

Addressed in 269c0d3.

session/setTitle no longer fails on sessions missing from the live sessions map. The handler now parses the thread id and updates SQLite first, then either delegates to Thread::set_title for loaded sessions or writes the title index directly for historical/listed sessions and emits SessionInfoUpdate from the agent connection. Added set_session_title_persists_unloaded_session to cover that path.