chat.agent — advanced & operational

The full, version-pinned reference ships inside your installed @trigger.dev/sdk. Read it before writing code — it always matches the SDK version in this project, so it never drifts:

• Skill: node_modules/@trigger.dev/sdk/skills/trigger-chat-agent-advanced/SKILL.md — Sessions primitive, custom transports/wire protocol, sub-agents, HITL, steering, actions, background injection, fast starts, resilience (compaction/recovery/OOM/large payloads), chat.local, testing, upgrades.
• Docs: the full, version-pinned docs ship bundled at node_modules/@trigger.dev/sdk/docs/ai-chat/ (including patterns/ for HITL, sub-agents, sessions); the skill above lists the exact pages it draws from in its sources: frontmatter. Grep for an API, e.g. grep -rl "mockChatAgent" node_modules/@trigger.dev/sdk/docs/.

If those paths don't exist, @trigger.dev/sdk isn't installed yet — install it first. In a non-hoisted layout, resolve the package with node -p "require.resolve('@trigger.dev/sdk/package.json')" and read skills/ + docs/ beside it.

Common mistakes

• CRITICAL: sending a follow-up by re-POSTing POST /api/v1/sessions.

  // Wrong - a cached re-POST silently drops basePayload.message; basePayload is trigger config, not a channel
  await fetch("/api/v1/sessions", { method: "POST", body: JSON.stringify({ ...createBody }) });
  // Correct - append to the session's input channel
  await fetch(`/realtime/v1/sessions/${id}/in/append`, { method: "POST", body: JSON.stringify({ kind: "message", payload }) });