Split monolith into smaller gateway/http services

[vcarl]

Context

Part of load balancer architecture work (see PR #228 for full analysis).

Risk: Medium | Reward: High | Code Changes: Required

Description

Add support for SERVICE_MODE environment variable to run the app in different modes:

• gateway - Only Discord gateway connection, no HTTP server
• http - Only HTTP server, no Discord gateway
• both (default) - Current behavior

Current State

Gateway and HTTP are tightly coupled in:

• app/server.ts (lines 39-63)
• app/discord/gateway.ts

Implementation

// app/server.ts
const serviceMode = process.env.SERVICE_MODE || 'both';

if (serviceMode === 'http' || serviceMode === 'both') {
  // Start Express HTTP server
}

if (serviceMode === 'gateway' || serviceMode === 'both') {
  // Initialize Discord.js gateway client
}

Tasks

• Add SERVICE_MODE to app/helpers/env.server.ts
• Refactor app/server.ts for conditional initialization
• Make app/discord/gateway.ts initialization optional
• Add tests for each mode
• Test HTTP-only mode in staging
• Test gateway-only mode in staging
• Document the new environment variable

Dependencies

None - this is foundational for the HTTP/Gateway split.

References

• PR Architecture analysis: Load balancing with SQLite constraint #228 (architecture analysis)
• Enables: HTTP service separation, Gateway StatefulSet

[vcarl]

this is maybe bullshit actually, this doesn't sound right. Seems like if we were going to do this work, we should really just carve it apart into separate services