fix(server): Claude MCP timeouts preserve the native session #25660 · pingdotgg/t3code

Before — main dd5b5401e1	After — fix 44a07ece34
Runtime transcript: pending delta retained; `/compact` replaced the native session.	Runtime transcript: pending delta restored; compaction and continuation retained the original session.

MmacroscopeappBotapproved these changes1d ago

Approvability

Verdict: Approved at 8f657bf

Macroscope's review found this PR approvable — This narrowly scoped server fix classifies MCP registration timeouts like other pre-prompt refusals, restoring pending handoffs so the existing native Claude session is retained. A focused regression test covers the behavior, with no product-default, schema, infrastructure, security, billing, or authentication changes.

No code changes detected at 384c16d. Prior analysis still applies.

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CcoderabbitaiBot1d ago

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Source mode: Auto
Repository: pingdotgg/t3code
Branch: fix/issue-22198
File: .coderabbit.config.ts
Commit: 384c16d
Layers: Repository TS config
Review profile: CHILL
Plan: Team
Run ID: 440780ed-829c-4604-b58e-e570d36b44d7

External image Commits

Reviewing files that changed from the base of the PR and between e2d3ded436f7b32c07aeb9bf7b4738bfef58156d and 384c16d8b994efa0b509bf8e28b8fcd2ee175de9.

External image Files selected for processing: 2

apps/server/src/orchestration-v2/ProviderTurnStartService.ts
apps/server/src/orchestration-v2/testkit/ProviderSwitch.integration.test.ts

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Walkthrough

The provider turn-start refusal check now recognizes Claude MCP registration timeouts, including when nested in a cause. The provider-switch integration test adds this timeout to the refused-turn cases.

Changes: Claude timeout refusal handling

Layer / File(s)	Summary
Recognize and test MCP registration timeouts `apps/server/src/orchestration-v2/ProviderTurnStartService.ts`, `apps/server/src/orchestration-v2/testkit/ProviderSwitch.integration.test.ts`	The refusal tag list includes `ClaudeMcpRegistrationTimeoutError`. The integration test simulates this error during `setMcpServers` and includes it in the refused-turn cases.

Priority: External image Normal

Estimated code review effort: 2 (Simple) | ~8 minutes

Change: Bug fix · Severity of issue fixed: Medium

Possibly related issues

Issue 23151 reports a Claude setMcpServers registration timeout and a provider-start failure. This change classifies that timeout as a pre-prompt refusal.

Possibly related PRs

pingdotgg/t3code#25372: Both changes address Claude MCP registration timeouts; this PR classifies the timeout as a pre-prompt refusal.
pingdotgg/t3code#22864: Both changes add an error to PROMPT_REFUSAL_TAGS in ProviderTurnStartService.
pingdotgg/t3code#23202: Both changes address the Claude MCP registration-timeout condition.

Suggested labels: bugfix

Suggested reviewers: only21mil

Merge Risk: External image Minimal · up to 384c1

The timeout refusal handling matches the production error path and the change is ready to merge.

Pre-merge checks: ^Passed 4

Check name	Status	Explanation
Title check	Passed	The title clearly and concisely describes the main change: preserving the native session after Claude MCP timeouts.
Description check	Passed	The description includes all required sections. It explains the problem, the fix, scope and approval, focused regression tests, broader verification, observed results, limitations, and tool usage.
Linked Issues check	Passed	Issue `#22198` requires the MCP registration timeout to be treated as a refusal when Claude has not received the prompt. The PR adds `ClaudeMcpRegistrationTimeoutError` to `PROMPT_REFUSAL_TAGS` in `Prov…
Out of Scope Changes check	Passed	The diff contains one server behavior change and its regression test. Both changes directly support issue `#22198`. No unrelated product behavior or unrelated files appear in the reviewed diff.

Full details: Linked Issues check

Explanation

Issue #22198 requires the MCP registration timeout to be treated as a refusal when Claude has not received the prompt. The PR adds ClaudeMcpRegistrationTimeoutError to PROMPT_REFUSAL_TAGS in ProviderTurnStartService.ts. The existing recursive cause check therefore restores unsent handoff bookkeeping for the wrapped ClaudeAgentSdkQueryRunnerError. ProviderSwitch.integration.test.ts adds the timeout regression case to the native-session retention test. The broader issue suggestions are follow-up behavior, and the PR explicitly limits its objective to the reported timeout trigger.

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Ggithub-actionsBot1d ago

Thread transfer impact

✅ Thread transfer remains within every enforced ceiling.

Provider	Metric	Main baseline	This PR	Impact	PR ceiling
Codex	Total thread wire	5.0 KiB	5.0 KiB	0 B (0.0%)	6.8 KiB	✅
Codex	Thread snapshot wire	3.8 KiB	3.8 KiB	0 B (0.0%)	4.9 KiB	✅
Codex	Live turn WebSocket wire	1.2 KiB	1.2 KiB	0 B (0.0%)	2.0 KiB	✅
Codex	Live turn WebSocket decoded	20.9 KiB	20.9 KiB	0 B (0.0%)	29.3 KiB	✅
Codex	Live turn messages	2	2	0 (0.0%)	8	✅
Claude	Total thread wire	5.0 KiB	5.0 KiB	0 B (0.0%)	6.8 KiB	✅
Claude	Thread snapshot wire	3.8 KiB	3.8 KiB	0 B (0.0%)	4.9 KiB	✅
Claude	Live turn WebSocket wire	1.2 KiB	1.2 KiB	0 B (0.0%)	2.0 KiB	✅
Claude	Live turn WebSocket decoded	21.2 KiB	21.2 KiB	0 B (0.0%)	29.3 KiB	✅
Claude	Live turn messages	2	2	0 (0.0%)	8	✅

Baseline: e2d3ded · PR result: 384c16d · Source CI: success

Scenario and decoded snapshot size

10 historical turns, 5 command tools per turn, 878.9 KiB retained MCP result per historical turn, and a 1.05 MiB retained result in the measured turn.

Codex decoded thread snapshot: 108.5 KiB
Claude decoded thread snapshot: 108.8 KiB

Updated in place by a trusted workflow. PR artifacts are strictly validated and never executed.

fix(server): Claude MCP timeouts preserve the native session#25660

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Thread transfer impact