chore: merge train 260821 — land #2281 (Claude Code thought-signature replay)

[lidge-jun]

Summary

Sixth leg of the merge train: lands #2281 — fix: enable call_id thought-signature replay for Claude Code plus the pre-merge normalization fix.

Review chain:

• Two independent adversarial reviews (inherited model): both PASS on merged head bc6d6b5
• Pre-merge blocker resolved by stacked commit bc6d6b5: promptCacheKey normalized via anthropicSessionKeyFromParts before scope assignment (trim + sha256-over-128 parity with the affinity path); overlong-hash and whitespace regression rows shipped — resolves the intake: hygiene-blocked label
• Security/privacy verified fail-closed: shared Desktop cohort blocked twice; replay cache keys carry full provider/adapter/model/credential identity tuple + serving-identity guard, so no cross-session or cross-account signature leak; stored scope is always the opaque translator hash, never raw user_id

Verification

• bun test tests/claude-code-thought-signature-scope.test.ts tests/google-signature-history-roundtrip.test.ts — 27/27 pass
• bun run typecheck / privacy:scan — pass
• Full suite on lidge at bc6d6b5: 14240 pass / 16 skip / 0 fail across 894 files, exit 0

Checklist

• Local CI green (full suite executed remotely on lidge at exact head)
• Branch includes the latest dev commit (train tracks origin/dev)
• No open Codex/CodeRabbit findings against this head
• Ready for review

Summary by CodeRabbit

• Bug Fixes

  • Improved Google response handling for thought signatures in nested response metadata, supporting more reliable tool-call replay and reasoning continuity.
  • Added safer Anthropic session handling for requests with per-session cache keys, including normalization of blank and overly long values.
  • Prevented shared cache cohorts from being used as individual replay sessions.

• Tests

  • Added regression coverage for Google signature preservation and Anthropic replay-session behavior.

[github-actions]

✅ Deterministic PR hygiene checks passed.

[coderabbitai]

Caution

Review failed

The pull request is closed.

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: Path: .coderabbit.yaml

Review profile: ASSERTIVE

Plan: Pro Plus

Run ID: fb42c6f2-d82c-49f1-a784-9f38dd648269

📥 Commits

Reviewing files that changed from the base of the PR and between 7d1b2ca and c836ffb.

📒 Files selected for processing (6)

• devlog/_plan/260821_bug_merge_train/000_triage_matrix.md
• devlog/_plan/260821_bug_merge_train/065_merge_2281.md
• src/adapters/google.ts
• src/server/responses/core.ts
• tests/claude-code-thought-signature-scope.test.ts
• tests/google-signature-history-roundtrip.test.ts

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📝 Walkthrough

Walkthrough

The change adds nested Google thought-signature handling and derives normalized Anthropic reasoning-replay scopes from eligible prompt cache keys. It adds regression tests and updates merge-train planning and triage records.

Changes

Reasoning replay updates

Layer / File(s)	Summary
Google thought-signature extraction src/adapters/google.ts, tests/google-signature-history-roundtrip.test.ts	Google parsing reads direct and nested thought signatures for streaming and buffered tool calls. The regression test verifies nested signature metadata.
Anthropic replay-scope derivation src/server/responses/core.ts, tests/claude-code-thought-signature-scope.test.ts	Anthropic requests without parent-thread headers derive replay scope identities from non-shared prompt cache keys. Tests cover shared, missing, oversized, and whitespace-only keys.
Merge-train execution record devlog/_plan/260821_bug_merge_train/000_triage_matrix.md, devlog/_plan/260821_bug_merge_train/065_merge_2281.md	The plan and triage entry record normalization, validation results, review status, and merged-into-train state.

Estimated code review effort: 3 (Moderate) | ~20 minutes

Sequence Diagram(s)

sequenceDiagram
  participant AnthropicRequest
  participant handleResponses
  participant anthropicSessionKeyFromParts
  participant OcxParsedRequest
  AnthropicRequest->>handleResponses: Send prompt_cache_key
  handleResponses->>anthropicSessionKeyFromParts: Normalize eligible key
  anthropicSessionKeyFromParts-->>handleResponses: Return normalized key or no key
  handleResponses->>OcxParsedRequest: Set _reasoningReplayScope

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Suggested reviewers: ingwannu, chilung-cgu

✨ Finishing Touches

📝 Generate docstrings

• Create stacked PR
• Commit on current branch

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch codex/merge-train-260821

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