Some Anthropic-compatible providers can return successful responses with
missing or partial usage metadata, especially after falling back to
non-streaming requests. Normalize usage at the provider response boundary so
transcript writes, side queries, and cost tracking continue without treating
token accounting as required response content.
Constraint: Third-party Anthropic-compatible providers do not always return complete usage fields.
Rejected: Add provider-specific handling | this is a protocol compatibility issue across proxies and gateways
Confidence: high
Scope-risk: moderate
Directive: Keep provider response normalization vendor-neutral; do not branch on provider names for missing usage fields.
Tested: bun test src/services/api/emptyUsage.test.ts src/utils/__tests__/thinking.test.ts src/server/__tests__/title-service.test.ts src/server/__tests__/conversations.test.ts
Tested: bun run check:server
Tested: bun run check:persistence-upgrade
Tested: git diff --check
Not-tested: Live Shengsuan Cloud provider replay
c45406054b