Feature Flags

Source: src/main.tsx (feature flag initialization) and various conditional imports

Overview

Claude Code uses build-time feature flags for dead-code elimination. When a feature is disabled at build time, all code paths for that feature are completely removed from the bundle by the Bun bundler.

Mechanism

Feature flags are evaluated via a feature() function call pattern:


if (feature("COORDINATOR_MODE")) {
  // This entire block is removed from the bundle
  // when COORDINATOR_MODE is disabled
  import("./coordinator/coordinatorMode");
}

The Bun bundler treats feature() calls as compile-time constants, enabling tree-shaking of disabled feature branches.

Known Feature Flags

Flag	Description
`KAIROS`	Assistant mode — alternative interaction pattern
`COORDINATOR_MODE`	Multi-agent coordinator for parallel task execution
`BRIDGE_MODE`	Remote session bridge for cloud execution
`VOICE_MODE`	Voice input/output capabilities
`Chicago_MCP`	Computer use via MCP
`DAEMON`	Background daemon worker processes
`WORKFLOW_SCRIPTS`	Workflow scripting system
`PROACTIVE`	Proactive suggestions and actions

Impact on Architecture

Feature flags affect:

Entry points — Conditional imports in main.tsx and cli.tsx
Commands — Feature-gated commands only registered when their flag is active
Components — UI elements conditionally rendered
Services — Service modules loaded only when needed

Build Variants

Different builds can enable different flag combinations, producing separate bundles optimized for each deployment target. This keeps the base bundle small while supporting advanced features in specialized builds.

Runtime vs Build-Time

Most feature flags are evaluated at build time for optimal bundle size. However, some flags can also be evaluated at runtime via:

Environment variables
Configuration files
GrowthBook (A/B testing service) integration in src/services/analytics/