fix(acp): bound extension requests with per-request timeout option

[kvnloo]

Problem

The ACP patched protocol's sendRequest awaited its response Deferred with no deadline. A wedged ACP agent that stays alive but never answers an extension request (e.g. cursor/list_available_models during Cursor model discovery) hung the caller forever — termination only rescued the dead-process case. This is the ACP twin of the unbounded codex app-server transport request fixed in #4.

Fix

Mirrors the #4 shape:

• request() accepts an optional timeout (AcpPatchedRequestOptions), default unbounded (existing behavior).
• On expiry the pending entry is dropped (a late response is ignored by resolveExtPending) and the request fails with the new AcpRequestTimeoutError (added to the AcpError union).
• AcpSessionRuntime.request() passes the option through; Cursor model discovery is now bounded at 30s.

session/prompt and the typed agent RPC path are untouched — turn-length prompts stay unbounded by design.

Validation

• New protocol.test.ts tests (TestClock, deterministic): timeout fires with AcpRequestTimeoutError (method, requestId, message), late response ignored, next request routes by id; plus a default-unbounded control.
• Red-on-base: timeout test hangs on base (15s vitest timeout FAIL). Green with fix: 29/29 (protocol.test.ts + errors.test.ts).
• tsc --noEmit clean on packages/effect-acp; touched server files verified against the new types (isolated check).
• vp fmt clean.

Files

• packages/effect-acp/src/protocol.ts — AcpPatchedRequestOptions, sendRequest timeout
• packages/effect-acp/src/errors.ts — AcpRequestTimeoutError + union
• packages/effect-acp/src/protocol.test.ts — 2 tests
• apps/server/src/provider/acp/AcpSessionRuntime.ts — option pass-through
• apps/server/src/provider/Layers/CursorProvider.ts — 30s bound on model discovery

Authored with AI assistance (Muse, Meta's Muse Spark) under the contributor's direction.

[coderabbitai]

Warning

Review limit reached

Next included review available in 59 minutes.

Check out review usage here.

View limit details

Limit details: You’ve used all 10 included reviews currently available.

Only developers with an assigned seat can use this organization's usage-based review budget, and seats here are assigned manually. Ask an admin to assign a seat, or change the review continuation mode in Billing.

Learn how review limits work.

Review configuration:

⚙️ Run configuration

Configuration used: Repository: pingdotgg/t3code/.coderabbit.yaml

Review profile: CHILL

Plan: Advanced

Run ID: ea61c190-6285-4bcc-a7d9-0eb9bfa42055

📥 Commits

Reviewing files that changed from the base of the PR and between ed57bed and 5cfffb8.

📒 Files selected for processing (5)

• apps/server/src/provider/Layers/CursorProvider.ts
• apps/server/src/provider/acp/AcpSessionRuntime.ts
• packages/effect-acp/src/errors.ts
• packages/effect-acp/src/protocol.test.ts
• packages/effect-acp/src/protocol.ts

---

_{Comment @coderabbitai help to get the list of available commands.}

[macroscopeapp]

Approvability

Verdict: Not approved

Macroscope's review found this PR not approvable — The PR adds tested, backward-compatible timeout plumbing, but changes Cursor model discovery from unbounded waiting to a 30-second failure deadline. That is a product-level default behavior change affecting an existing path and warrants deliberate review.

Notes:

• Diff unchanged. Approvability was decided on eligibility alone.

^{You can add or adjust custom eligibility rules. Learn more.}

Dismissing prior approval to re-evaluate 5cfffb8