storage: @relayburn/server package + HttpAdapter (Phase 4 of #139)

[willwashburn]

Phase 4 of #139. Depends on Phase 1 (seam) and Phase 3 (Postgres, used as the server's backing store). Phase 2 (SQLite) is also useful as the server's local-dev backing store.

Goal

Stand up a relayburn collector service so burn instances running on remote/ephemeral hosts can ship their data over HTTP instead of needing direct database credentials. Two pieces:

1. @relayburn/server — a new package: a minimal Node HTTP service that holds one StorageAdapter instance internally and exposes its operations as a REST API.
2. HttpAdapter — an adapter inside @relayburn/ledger that talks to that server.

Selected via RELAYBURN_STORAGE=http + RELAYBURN_SERVER_URL=https://… + RELAYBURN_API_KEY=….

@relayburn/server package

packages/server/ — minimal node:http + tiny route table (no Express/Fastify). Uses one of the durable adapters internally (Postgres in production, SQLite for local dev) by reading the same RELAYBURN_STORAGE / RELAYBURN_DATABASE_URL env vars.

• Auth via static API-key list: RELAYBURN_API_KEYS=key1,key2,…. Authorization: Bearer <key> required on every endpoint; 401 otherwise.
• CLI entry: relayburn server --port 8080 (wired into packages/cli/src/cli.ts).
• Endpoints under /v1/:
  • POST /v1/turns, POST /v1/content, POST /v1/compactions, POST /v1/relationships, POST /v1/tool-result-events, POST /v1/user-turns, POST /v1/stamps — append batches; idempotent via content-addressed hashes from index-sidecar.ts.
  • GET /v1/turns?… (and parallel endpoints) — streaming NDJSON response feeding the client's queryTurns async iterable.
  • POST /v1/locks/{name}/acquire + POST /v1/locks/{name}/release — cross-host coordination via the server's underlying adapter withLock.

HttpAdapter

packages/ledger/src/adapters/http-adapter.ts — plain fetch client implementing the StorageAdapter interface.

• Bearer-token auth from RELAYBURN_API_KEY.
• Retries with exponential backoff on transient errors (5xx, network).
• No client-side dedup beyond what the server's underlying adapter applies — keeps the client thin.
• Streaming reads parse NDJSON line-by-line into the queryTurns async iterable.

Files

• New package: packages/server/ with src/server.ts, src/routes.ts, src/auth.ts, package.json, tests.
• New: packages/ledger/src/adapters/http-adapter.ts.
• Modified: packages/ledger/src/adapters/factory.ts — wire up http branch.
• Modified: packages/cli/src/cli.ts — add relayburn server subcommand.
• Modified: root package.json — add packages/server to the workspace.

Verification

• End-to-end: spin up relayburn server against SQLite locally; run CLI with RELAYBURN_STORAGE=http RELAYBURN_SERVER_URL=http://localhost:8080; ingest a fixture; query results from both client (over HTTP) and server (direct adapter) match exactly.
• Auth: missing/invalid RELAYBURN_API_KEY → 401.
• Resilience: kill the server mid-ingest, restart it — no data loss, no duplicates after retry.
• Parameterized adapter test suite (from Phase 2) passes against the HttpAdapter pointed at an in-process server backed by SQLite.