GMW/services/discord-gateway/AGENTS.md

Discord Gateway — Agent Guide

Read ../../AGENTS.md first. This file adds gateway-specific conventions.

Event-driven microservice: captures Discord events, runs AI moderation, publishes to Redis.

Quick reference

pnpm typecheck              # tsc --noEmit
pnpm lint                   # biome check --diagnostic-level=error .
pnpm build                  # tsc
pnpm test                   # vitest run
pnpm format                 # biome format --write .

Architecture (Event-driven)

src/
├── index.ts                     # Entry point → initializeDiscordGateway()
├── app/
│   ├── bootstrap.ts             # Wires client, DB, Redis, workers, schedulers
│   ├── shutdown.ts              # Graceful shutdown
│   └── retention.ts             # Expired-record cleanup
├── shared/
│   ├── config/index.ts          # Zod-validated env (SINGLE source of truth)
│   ├── database/                # Drizzle ORM + pg Pool + migrations
│   ├── logger/index.ts          # pino + createChildLogger()
│   ├── errors/index.ts          # AppError hierarchy
│   ├── utils/                   # retry, pagination
│   ├── discord/clientOptions.ts # discord.js-selfbot-v13 options
│   ├── uploader.ts              # Attachment upload helper
│   ├── redis-channels.ts        # Redis channel-name constants
│   └── moderation-types.ts      # Shared AI analysis types
├── modules/
│   ├── ai-moderation/           # LLM moderation pipeline (largest module)
│   ├── message-capture/         # Discord event listeners + DB store
│   ├── attachment-upload/       # Download + sharp resize + upload
│   ├── event-broadcaster/       # Redis pub/sub publisher
│   ├── command-handler/         # Backend→gateway Redis commands
│   ├── reaction-tracking/       # Reaction events
│   ├── thread-tracking/         # Thread events
│   ├── user-presence/           # Presence/status events
│   ├── channel-topic/           # Channel topic events
│   ├── guild-member-events/     # Member join/leave
│   └── gateway-metrics/         # Prometheus /metrics (port 4016)
└── tests/                       # Vitest suites

Key invariants (DO NOT BREAK)

1. LLM is the only judge. Failed LLM → status:"error" + recovery retry. Never reintroduce regex/heuristic content classification.
2. Discord tokens sanitized before reaching LLM (discordTokens.ts).
3. Streaming is mandatory against the router base URL.

AI moderation pipeline

aiAnalyzer.ts → batchScheduler.ts → batchProcessor.ts → individualFallbackProcessor.ts
    ↓                  ↓                    ↓                        ↓
moderationOrchestrator.ts → (hash cache → LLM)
    ↓                          ↓                              ↓
textBatchProcessor.ts    mediaBatchProcessor.ts         llmClient.ts

• Entry: aiAnalyzer.ts (queueMessageAnalysis, startPendingAIAnalysisWorker)
• Concurrency: two per-lane LLM semaphores (2026-09-24) — text (AI_LLM_MAX_CONCURRENT, default 8) and media/vision (AI_LLM_MEDIA_MAX_CONCURRENT, default 4); a media backlog can never consume text slots
• Piscina: text pool (4 threads) + media pool (2 threads)
• Locks are per conversation per lane (conversationProcessing maps key → lane → startedAt): the text lane of a conversation never waits on that conversation's media lane (this was the "image blocks the queue" bug)
• Each worker thread has its own pg Pool (min 0, grows to POSTGRES_POOL_MAX)

Module: message-capture

• messageCapture.ts — Discord event listeners (messageCreate/Update/Delete)
• messageStore.ts — DB operations
• messageMetadata.ts — metadata extraction
• messagesDb.ts / messagesCrud.ts — DB schema operations
• retentionDb.ts / reviewsDb.ts / attachmentsDb.ts — auxiliary tables

Redis channels (outbound to backend)

See src/shared/redis-channels.ts for canonical names. Examples:

discord:message:created, discord:moderation:action, discord:attachment:uploaded

Config (env vars)

All validated via Zod in shared/config/index.ts. Critical:

• DISCORD_TOKEN — selfbot token
• MONITOR_GUILD_ID — primary guild
• DATABASE_URL — PostgreSQL
• REDIS_URL — pub/sub to backend
• AI_ANALYSIS_ENABLED — master toggle for AI moderation
• AI_LLM_BASE_URL / AI_LLM_API_KEY — LLM router
• PISCINA_MAX_THREADS / PISCINA_MEDIA_MAX_THREADS — worker pool sizing

Concurrency model

• Main thread: event loop + LLM semaphore
• Text Piscina pool: PISCINA_MAX_THREADS (default 4)
• Media Piscina pool: PISCINA_MEDIA_MAX_THREADS (default 2)
• Batch routed to media pool if ANY message has attachment/sticker/embed
• Each worker thread initializes own pg Pool (min 0, grows to POSTGRES_POOL_MAX)
• MemoryMax: 1G (service systemd limit)

Testing

• Vitest. Test files: tests/<name>.test.ts
• Run: pnpm test
• Key test areas: batch operations, cache guards, image/video handling, context enrichment
• Unit tests for pure helpers (classifier, normalize, parse), integration for pipeline stages

Common pitfalls

• Piscina pool isolation: worker threads are NOT the main thread. Cannot share state via module-level variables. Use DB or Redis for cross-thread state.
• Cache eviction: LRU caches (user metadata, term glossary) evict at max size. Don't assume cache hit after eviction.
• Circuit breaker: per-conversation CB opens after repeated failures. Check circuitBreaker.ts state when debugging "missing analysis".
• Gateway≠Backend schema: both have redis-channels.ts and moderation-types.ts. Keep them in sync manually.