- puterProxyService with storeToken (create/rotate idempotent), resolveToken, chatStream
- chatStream relays to Puter OpenAI-compat endpoint with SSE streaming
- Cost recording with provider=puter, billingType=subscription_included, costCents=0
- Cost recording skipped when agentId is null/undefined (no FK violation)
- puterProxyRoutes with POST /puter-proxy/token and POST /puter-proxy/chat
- Board auth (assertBoard + assertCompanyAccess) on all routes
- All 10 TDD tests passing