* docs: add brainstorm report for discord guild-user memory
* docs: update brainstorm report with corrected root cause analysis
* feat(discord): per-user memory scope in guild channels
Fixes shared USER.md between guild members by scoping userID to
"guild:{guildID}:user:{senderID}" for Discord group messages.
Updates all group-context prefix checks (write permissions, writer
cache, cron peer kind, history filter) to include the new guild: prefix.
Closes#165
Add optional Redis cache support via `go build -tags redis`, following
the same paired-stub pattern as OTel and Tailscale. The Cache[V] interface
is unchanged; Redis and in-memory implementations are injected at startup
without altering usage logic.
- Add RedisCache[V] implementation with JSON serialization, fail-open on errors
- Add gateway_redis.go / gateway_redis_noop.go paired wiring files
- Refactor GroupWriterCache and ContextFileInterceptor to accept injected caches
- Add GOCLAW_REDIS_DSN env var, docker-compose.redis.yml overlay
- Update Dockerfile and GitHub Actions with ENABLE_REDIS build arg
- Add Redis variant to CI matrix (5 variants: latest, otel, tsnet, redis, full)
