+*******
+ Probe
+*******
+
+``onechat probe LOG COUNT [BUILDS]`` measures the compactor on a log. It
+appends the first COUNT messages of LOG, one JSON object ``{"kind",
+"text"}`` on each line, to a new chat in ``probe/`` in the data
+directory, and builds its tree with real model calls. The calls use the
+quota of the account. The run stops at the first failed call, after 660
+calls, or when the used percent of a quota window grows by more than 15
+points. At the end it reports the calls per message, the cached share of
+the input tokens, the retries, the line sizes, and the quota at the
+first and the last call. BUILDS, from 1 to 8, limits the model calls at
+once in the run.
+
+A test writes a generated log of readable made-up messages:
+
+.. code:: console
+
+ ONECHAT_PROBE_LOG=probe.jsonl go test -run TestProbeLogHasTheSyntheticMix
+