Sessions
Session plugins record what happened in an agent run (service id session). You need one session plugin. You can wrap it with another.
| Plugin | Role |
|---|---|
| Disk | Default local. JSONL while live, then JSON and markdown. |
| SQL | Rows on a named SQL schema. Worker-safe. |
| Stream | In-memory subscribe() wrap around another session. |
| Memory | In-memory only. No SQL or filesystem. |
Ids you will see
| Id | Who owns it | Meaning |
|---|---|---|
runId | you | One prompt turn; use it to cancel |
sessionId | you | Your session record |
acpSessionId | the agent | The agent’s own session id |
ACP session/new receives this runtime’s MCP server once HTTP is listening (http://127.0.0.1:<port>/mcp). Buildautomaton prompt sessions use those tools so they can report completed work.