capture R NNN [--public] (--deadline D|--timeout-ms MS) --after PREV --hypothesis 'TEXT' -- CMD
publishes exploration-NNN.json {observationCapture, observationArgv, observed, hypothesis,
nextCapture, nextArgv} before running CMD, refusing unless PREV is the latest complete capture.
The receipt carries checkpoint/checkpointSha256; validators bind the note to the transcript's
capture calls by capture ID and receipt hash instead of exact command strings. The separate
checkpoint command and the capture guard keep working; materialize learning accepts both note
shapes and still rejects same-probe replays. Prose and eval fixture prompts teach the merged form.