[Task 10] Wire Anthropic /v1/messages

[lubobill1990]

Task 10 — Wire Anthropic /v1/messages

Depends on: 06
Unblocks: 11

Goal

Both streaming and non-streaming Anthropic /v1/messages requests record one
row each, using normalizeAnthropicMessage or the Anthropic stream
accumulator.

Scope

In src/routes/messages/handler.ts (and any proxy code that fans events to
the client):

• Non-stream: parse response.usage via normalizeAnthropicMessage.
• Stream:
  • Build an createAnthropicAccumulator().
  • Feed every event passing through.
  • On message_stop (final event): recordUsage(... finalize() ..., status: 'ok').
  • On abort: status: 'aborted'.
  • On error: status: 'error'.
• endpoint = 'messages', upstreamFormat = 'anthropic'.

Edge cases

• The Anthropic stream's output_tokens in message_delta.usage is
  cumulative — accumulator must track the maximum, not sum.
• Tool calls and thinking blocks: counted via output_tokens in the cumulative
  delta. reasoningTokens stays at 0 in v1.

Definition of Done

• Non-streaming /v1/messages produces a row with upstream_format = 'anthropic'.
• Streaming /v1/messages produces a row whose output_tokens matches
  the final message_delta.usage.output_tokens (not the sum of deltas).
• Cache-related fields populate cached_input_tokens and add into
  input_tokens per the rules in design doc 02.

---

• Source: docs/tasks/10-wire-anthropic-messages.md
• Design: docs/design/
• Phase: wiring
• Depends on tasks: 6