Capabilities

Self-contained subsystems that register themselves at startup. Add features without touching core bridge code.

How it works

On boot, discoverCapabilities() scans src/capabilities/ for directories with a capability.json manifest. Each is dynamically imported and its register(api) function called.

Built-in capabilities

Capability	What it provides
Browser	Browsie subagent, browse-checker heartbeat task, SSRF guard
Hotskills	Live-reload skill files, eligibility gating via requires frontmatter
Sleep	Dreamy spawn + retry, progress protocol

Adding a capability

1. Create src/capabilities/<name>/capability.json:

   { "name": "my-feature", "description": "What it does" }

2. Create src/capabilities/<name>/index.ts:

   import { CapabilityApi } from '../capability';
   
   export function register(api: CapabilityApi): void {
     // Register commands, heartbeat tasks, services
     api.registerHeartbeatTask('my-task', async () => { /* ... */ });
   }

3. Restart bridge — auto-discovered, no wiring needed.

CapabilityApi

What a capability can register:

Method	Purpose
registerHeartbeatTask(name, fn)	Runs every heartbeat tick (5 min)
registerCommand(name, handler)	Chat command
registerService(name, service)	Background service with start/stop lifecycle
runtime	Access to SubagentRuntime for spawning agents

Disabling capabilities

# ~/.abtars/config/.env
DISABLED_CAPABILITIES=browser,hotskills

Comma-separated names. Disabled capabilities are skipped at discovery — zero overhead.

Replacing a capability

1. Drop a new capability directory (e.g. browser-v2/)
2. Disable the old one: DISABLED_CAPABILITIES=browser
3. Restart — old one skipped, new one loads