Core TypeScript Types

Message Types

type Message =
  | UserMessage         // User input with content blocks
  | AssistantMessage    // AI response (text, tool use)
  | SystemMessage       // System instructions
  | ProgressMessage     // Progress updates
  | TombstoneMessage    // Deleted/replaced messages
  | AttachmentMessage   // File attachments

type PermissionMode = 'default' | 'auto' | 'bypass'

type ToolProgressData =
  | BashProgress        // Shell output streaming
  | WebSearchProgress   // Search result streaming
  | MCPProgress         // MCP operation progress
  | AgentToolProgress   // Sub-agent status
  | TaskOutputProgress  // Task result display

Try This

Count the message types (6 total). Each serves a purpose. TombstoneMessage replaces deleted messages - why not just remove them? Because the API needs message ordering preserved.

Design Patterns

1. Build-Time Feature Gating

Uses Bun's feature() for dead code elimination at bundle time.

2. Lazy Circular Dependency Breaking

Uses lazy require() wrappers to break circular imports.

3. Ant-Only Code Elimination

Internal features eliminated from external builds via constant folding.

4. React Context State Management

Central AppState with getter/setter pattern and memoized selectors.

Try This

Go to the Feature Flag Simulator. Toggle COORDINATOR_MODE on. At build time, Bun's feature() includes the coordinator code. Toggle it off - that entire code block is removed from the bundle. Dead code elimination in action.

All Feature Flags

Flag	Type	Purpose	Status
`COORDINATOR_MODE`	Build	Multi-agent teams	Internal
`KAIROS`	Build	Proactive assistant	Internal
`VOICE_MODE`	Build	Voice I/O	Beta
`BRIDGE_MODE`	Build	IDE bridge	Active
`TRANSCRIPT_CLASSIFIER`	Build	Auto-mode classifier	Internal
`DIRECT_CONNECT`	Build	Direct API	Beta
`SSH_REMOTE`	Build	SSH remote	Beta
`PROACTIVE`	Build	Proactive tools	Internal
`AGENT_TRIGGERS`	Build	Cron tools	Beta
`AGENT_TRIGGERS_REMOTE`	Build	Remote triggers	Beta
`MONITOR_TOOL`	Build	System monitor	Internal
`WORKFLOW_SCRIPTS`	Build	Workflows	Beta
`HISTORY_SNIP`	Build	History snip	Internal
`WEB_BROWSER_TOOL`	Build	Web browser	Internal
`PUSH_NOTIFICATION`	Build	Push notifications	Internal
`tengu_scratch`	Runtime	Scratchpad	Internal
`tengu_onyx_plover`	Runtime	AutoDream config	Internal
`tengu_ccr_bridge_multi_session`	Runtime	Multi-session	Beta

Try This

Go to the Feature Flag Simulator. Enable all 8 flags and count the available tools. Now disable all flags - how many tools remain? The difference shows how much functionality is feature-gated.