perf(chat): remove quota and admission round trips

[tannerlinsley]

A live Assistant trace spent 916 ms reserving usage and 555 ms across two admission guards before reaching the model. Reservation now runs the existing lock, fresh role check, quota checks, and atomic accounting protocol inside one PostgreSQL call. Each ordinary admission guard reads current permissions and bot/thread lifecycle together, while retaining both pre- and post-preparation checks and the extra lifecycle check after retry readiness.

The migration uses a SECURITY INVOKER, VOLATILE function and the existing advisory lock keys, so old and new workers remain compatible during deployment. Deployment migrates and verifies the schema before releasing the worker.

Validation: full pnpm test, 278 real PostgreSQL runtime tests, including quota concurrency, revocation while waiting on a lock, admin role revocation, retries, and scope/lifecycle checks. Live phase timings are retained for the post-deployment comparison.

Summary by CodeRabbit

• Performance
  • Reduced application overhead when reserving chat runs. Provider response times and response quality are not guaranteed to change.
• Bug Fixes
  • Preserved access checks during chat-run reservations, including when permissions change while a reservation is waiting.
  • Continued enforcing user, shared spending, daily turn, and scheduled-turn limits, including for admins.

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Latest commit: 60a0942

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📥 Commits

Reviewing files that changed from the base of the PR and between 01bcb35 and 60a0942.

📒 Files selected for processing (9)

• docs/tanchat-send-latency.md
• drizzle/migrations/0041_tanchat_usage_reservation.sql
• drizzle/migrations/meta/_journal.json
• harness-tests/core/run-usage-admin.test.ts
• harness-tests/pending-runtime/run-usage-admin.test.ts
• scripts/verify-tanchat-schema.ts
• src/chat/conversation-identity.server.ts
• src/chat/server/conversation.ts
• src/chat/server/run-usage.ts

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Status	Name	Latest Commit	Updated (UTC)
✅ Deployment successful! View logs	tanstack-com	60a0942	Oct 05 2026, 07:25 AM