Systems

The architectural building blocks that don't map cleanly to a single app or feature. These are cross-cutting concerns that show up everywhere in the codebase.

System	Role	Page
Database	Multi-DB schema, migrations, load balancing	Database
Authentication	Login, sessions, token validation	Authentication
Authorization	declarative_policy ability checks	Authorization
Sidekiq jobs	Async work patterns and routing	Sidekiq jobs
EventStore	Domain pub/sub	EventStore
Feature flags	Flipper-based runtime gating	Feature flags
Search	Elasticsearch + Zoekt + Active Context	Search
Banzai	Markdown / HTML pipeline	Banzai
Gitaly client	gRPC bridge to Gitaly	Gitaly client
Object storage	CarrierWave + S3-compatible	Object storage
Rate limiting	Centralized Redis throttle	Rate limiting
Internal events	Schemaful product analytics	Internal events
ClickHouse	OLAP for analytics	ClickHouse
Geo replication	EE-only cross-region replication	Geo