Interoperability

The universal integration is a shell command plus a Markdown skill. All integrations are optional and thin; vendor-specific code lives in separate packages and is tested with recorded fixtures, so core schema evolution never depends on a vendor release.

The adapter contract

Adapters implement BatonAdapter from @baton/adapter-sdk:

interface BatonAdapter {
  getProjectContext(): Promise<ProjectContext>;        // root, id, initialized
  getSessionMetadata(): Promise<SessionMetadata>;      // harness, opaque id, model
  subscribeEvents?(handler: (event: AdapterEvent) => void): () => void;
  renderNotice?(input: RenderNoticeInput): void;
}

Rules:

• No adapter may require raw messages or hidden prompts.
• AdapterEvent carries only normalized 0–1 signals plus the harness name and an optional opaque session id.
• Evaluate events with evaluateEvent(event, config, lastPromptAt, previousPressure) from @baton/core, or shell out to baton detect --event '<json>' for identical semantics, cooldown handling, and JSON contract.
• Automation recommends and prepares; it never terminates a session or launches another agent.

Environment matrix (spec §15)

Environment	MVP integration	Automation signal	Resume path
Claude Code	Project skill; optional PreCompact hook	explicit command; hook event	/baton-resume-style command or baton resume
Codex	Project instructions + MCP config	explicit command; session boundary	MCP handoff_resume or CLI brief
Cursor	Project rule + terminal task	explicit action; user-triggered new chat	paste rendered resume brief
Gemini CLI	Project command/extension; MCP if supported	explicit command; lifecycle hook if stable	CLI or MCP resume
Open-source harnesses	npm package + CLI; documented event adapter	normalized detect --event JSON	CLI/MCP

Event format

{
  "harness": "your-harness",
  "session_id": "opaque-or-null",
  "material_event": "pre_compaction",
  "signals": {
    "contextPressure": 0.92,
    "turnPressure": 0.6,
    "elapsedPressure": null,
    "workBoundary": false,
    "handoffRequest": false,
    "changePressure": 0.4,
    "stuckSignal": null,
    "resumeReadiness": 0.9
  }
}

Unavailable signals are null, never guessed. The detector's output includes the inputs actually used and human-readable reasons, so every recommendation is auditable. See examples/adapter-events/events.json for fixtures.