Stage 1: backend foundation (Postgres, sessions, accounts, OTel)

- internal/postgres: pgx-over-database/sql pool (otelsql), embedded goose
  migrations into schema 'backend', committed go-jet code + cmd/jetgen tool.
- internal/account: durable accounts + unified telegram/email identities
  (UUIDv7 keys), find-or-create provisioning with unique-conflict handling.
- internal/session: opaque 256-bit tokens stored as a SHA-256 hash, revoke-only
  (no TTL); write-through cache gating /readyz; store + service.
- internal/telemetry: OTel tracer/meter providers (none/stdout) + request-timing
  middleware; internal/config gains Postgres + OTel env loading.
- internal/server: /api/v1 {public,user,internal,admin} skeleton + X-User-ID
  middleware; /readyz checks DB ping + cache; main wires
  telemetry -> db+migrate -> warm cache -> server.
- Tests: unit + integration (build tag 'integration', testcontainers
  postgres:17) for migrations, accounts, sessions, readyz; new integration.yaml.
- Docs: ARCHITECTURE, TESTING, PLAN refinements, root + backend READMEs.

Session/account REST handlers deferred to Stage 6 (gateway); OTLP + dashboards
to Stage 11.

CLAUDE.md

@@ -60,8 +60,8 @@ conversation memory — is the source of continuity. Keep it that way.
 ## Stack
 
 Go 1.26.3, `go.work` monorepo, module paths `scrabble/<name>`. Dependencies are
-added **when first used** (incremental): backend currently uses only `gin` +
-`zap`; pgx/goose/jet/OTel arrive with Stage 1+. Client↔gateway is Connect-RPC +
+added **when first used** (incremental): backend uses `gin` + `zap` +
+`pgx`/`go-jet`/`goose`/OTel (added in Stage 1). Client↔gateway is Connect-RPC +
 FlatBuffers (h2c); gateway↔backend is REST/JSON + `X-User-ID` plus a gRPC
 server-stream for live events. UI is pure HTML5/CSS on plain Svelte + Vite,
 packaged to native with Capacitor. Likely no Redis.
@@ -100,9 +100,15 @@ Constraints:
 ```
 go.work                      # use the existing modules; grows per stage
 backend/                     # module scrabble/backend
-  cmd/backend/               # main: boots HTTP listener
-  internal/config/           # env config
-  internal/server/           # gin engine, /healthz, /readyz, lifecycle
+  cmd/backend/               # main: telemetry -> db+migrate -> cache -> server
+  cmd/jetgen/                # dev tool: regenerate go-jet code (throwaway container)
+  internal/config/           # env config (composes postgres + telemetry)
+  internal/telemetry/        # OTel providers + request-timing middleware
+  internal/postgres/         # pgx/database-sql pool, goose migrations/, jet/ (generated)
+  internal/account/          # durable accounts + identities (store)
+  internal/session/          # opaque tokens, sessions store, cache, service
+  internal/server/           # gin engine, /api/v1 groups, X-User-ID, probes
+  internal/inttest/          # //go:build integration Postgres-backed tests
 docs/  .gitea/workflows/  PLAN.md  CLAUDE.md  README.md
 gateway/  ui/  pkg/  platform/   # added by their stages
 ```