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.
Each instance runs one CLI role: api or billing-consumer (see src/bin/run.ts).
Stateless per-instance: no local state that matters across requests.
Cross-instance coordination via Redis Pub/Sub (WebSocket broadcast) and Redis Streams (billing events).
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 (Postgres tx + Redis Stream XADD). Never put write-balance logic in flux.ts.
LLM gateway proxy: /api/v1/openai forwards to GATEWAY_BASE_URL. Server handles auth/billing/logging — not model execution.
Redis is cache + messaging, not truth: balance cache, app_settings read cache, WS cross-instance pub/sub, billing event streams. 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 and Streams. No in-process singletons that hold mutable state across requests.

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/outbox/Streams
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 — CLI roles, outbox, Streams consumer
observability-conventions.md — OTel naming, custom attributes

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