ctrlrun.JSONLEventSink — class, defined at src/ctrlrun/receipt.py:429
receipts.jsonl and events.jsonl beside the state database, so .ctrlrun/ holds the
whole record of what an agent did. The store is authoritative — these files are the
portable copy, written after the store accepted the same record.
Each write opens, appends one line and closes, so several processes sharing a store
(SPEC-v0.1 §5.3 E1) interleave whole lines rather than fragments of them.
SPEC-v0.2 §4.3 — this used to live inside SQLiteStateStore, which wrote both halves.
Control owns it now, as one EventSink among however many an application registers.
The files it writes, and where, are unchanged.