Expand description
Per-call JSONL statistics.
One line per cached call, in the shape verdant stats and
verdant audit already parse: {ts_us, tool, outcome, duration_us, args_summary}, with outcome one of hit, miss, uncached or
invalidate. Both the MCP tool layer and the LLM proxy emit it, and
the reporting side reads whichever file it is pointed at, so the
shape is one rule and lives here rather than once per producer.
Recording is best-effort throughout: a statistics write that failed must never turn a served request into an error, so every failure path returns quietly. The file is opened per call rather than held, which keeps the recorder cheap to clone and share across the proxy’s per-request threads; a cached call is already in the millisecond regime or slower, so the open is not on any hot path.