feat(chat): add ephemeral store-and-forward messaging

[codenamed22]

Summary

• add authenticated direct and small-group messaging for active ShardUp members
• persist conversation metadata and transient per-recipient deliveries in PostgreSQL, deleting payloads after browser acknowledgement
• keep delivered history locally in IndexedDB with reconnect/inbox recovery and idempotent sends
• add a self-hosted, stateless WebSocket gateway with JWT authentication, origin checks, protected publish access, heartbeats, and hardened Docker deployment
• add responsive desktop/mobile messaging UI, member-profile entry points, cleanup cron, health checks, and deployment documentation

Architecture

Messages are committed to the transient PostgreSQL inbox before best-effort realtime fan-out. Connected recipients persist envelopes in IndexedDB and ACK them; offline recipients recover the same envelopes from /api/chat/inbox. The final recipient ACK deletes the server payload. Undelivered payloads expire after 30 days.

The WebSocket gateway stores only live socket references. Redis is intentionally deferred until multiple gateway replicas require cross-process fan-out.

Deployment

• migration: 20260808120000_add_ephemeral_chat
• required app variables are documented in .env.example
• gateway Docker/Caddy setup is documented in docs/chat-gateway.md
• Vercel cron calls /api/cron/chat-cleanup daily

Verification

• npm run typecheck
• npm run lint
• npm run format:check
• npm run test:unit — 120 tests passed
• full Playwright suite — 30 tests passed against local PostgreSQL with a clean fake-judge server
• npm run build
• authenticated public WebSocket publish/receive smoke test passed against the deployed gateway

[vercel]

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Project	Deployment	Actions	Updated (UTC)
shardup-site	Ready	Preview	Aug 13, 2026 7:20pm