airi/apps/server/CLAUDE.md

Server CLAUDE.md

Agent-facing guide for apps/server. Detailed topic docs live in docs/ai-context/ — read the relevant file before modifying that area.

Overview

Hono-based Node.js backend. Owns auth, billing, chat sync, LLM gateway forwarding, and observability. Multi-instance deployed on Railway — design all features assuming N>1 instances sharing the same Postgres and Redis.

Deployment Model

• Hosted on Railway, multiple instances behind a load balancer.
• Single CLI role: api (see src/bin/run.ts). No background polling loops, no fire-and-forget tasks — every write happens inside the request thread.
• Stateless per-instance: no local state that matters across requests.
• Cross-instance coordination via Redis Pub/Sub (WebSocket broadcast). DB-level idempotency ((userId, requestId) partial unique index on flux_transaction) covers retries.
• Rate limiting is currently in-memory (not distributed) — keep this in mind when adding rate-sensitive features.

Tech Stack

Hono, Better Auth (OIDC provider, RS256 JWT), Drizzle ORM, PostgreSQL, Redis, Stripe, OpenTelemetry, Valibot, injeca (DI), tsx.

Commands

pnpm -F @proj-airi/server dev                # dev with dotenvx (.env.local)
pnpm -F @proj-airi/server typecheck
pnpm -F @proj-airi/server exec vitest run    # all server tests
pnpm exec vitest run apps/server/src/...     # single test file
pnpm -F @proj-airi/server db:generate        # drizzle-kit generate
pnpm -F @proj-airi/server db:push            # drizzle-kit push
pnpm -F @proj-airi/server auth:generate      # better-auth → src/schemas/accounts.ts

Local observability: docker compose -f apps/server/docker-compose.otel.yml up -d

Architecture Summary

Entry & DI: src/app.ts (createApp()) → logger, env, OTel, Postgres/Redis, DB migrations, services via injeca, routes/middleware. CLI entry src/bin/run.ts.

Layering:

• Routes (src/routes/): thin — param validation (Valibot), auth guards, error mapping. No business logic here.
• Services (src/services/): core business logic and DB transactions.
• Schemas (src/schemas/): Drizzle table definitions. Migrations in @proj-airi/server-schema.

Middleware chain (/api/*): CORS → hono/logger → optional otel → sessionMiddleware → bodyLimit(1MB) → per-route guards. WebSocket /ws/chat registered before bodyLimit.

Error model: ApiError(statusCode, errorCode, message, details) in src/utils/error.ts.

Key Design Decisions

• Flux read/write separation: FluxService reads (Redis cache-aside), BillingService writes (single Postgres tx that mutates user_flux and writes the matching flux_transaction ledger row). Never put write-balance logic in flux.ts.
• No async billing pipeline: debits and credits update balance + ledger in one transaction. The (user_id, request_id) partial unique index gives DB-level idempotency for retries; LLM request log rows are written best-effort right after the response is delivered.
• In-process LLM/TTS router: /api/v1/openai is dispatched by services/domain/llm-router reading LLM_ROUTER_CONFIG (per-model upstream chain + envelope-encrypted keys). chat/completions walks LLM upstreams with key fallback; audio/speech delegates to a TTS adapter (azure / dashscope-cosyvoice / volcengine); audio/voices returns the adapter's compiled-in catalog. Server handles auth/billing/logging, not model execution.
• Redis is cache + pub/sub, not truth: balance cache, app_settings read cache, WebSocket cross-instance pub/sub. Truth is always Postgres.
• Auth: Better Auth + OIDC. sessionMiddleware fills context but doesn't block; authGuard returns 401.
• Multi-instance safe: all writes go through Postgres transactions; cross-instance messaging uses Redis Pub/Sub. No async work, no in-process singletons — admin flux grants happen synchronously inside the POST that triggered them.

Detailed Context Docs

See docs/ai-context/README.md for the full index. Key files:

• architecture-overview.md — entry, DI, assembly, boundaries
• transport-and-routes.md — API surface, route→service mapping
• data-model-and-state.md — tables, state ownership, caching
• billing-architecture.md — Flux/Stripe ledger
• redis-boundaries-and-pubsub.md — Redis key/channel boundaries
• auth-and-oidc.md — auth flows, OIDC, trusted clients
• config-and-naming-conventions.md — configKV, naming rules
• workers-and-runtime.md — single api role, no background loops, no fire-and-forget; everything is synchronous in-request
• admin-flux-grants.md — synchronous one-shot flux grant endpoint (no batch tables, no state machine)
• observability-conventions.md — OTel naming, custom attributes