TODO.d: black-box segments carry a start_time offset, slice offsets must subtract it

TODO.d/2026-11-01-moment-capture.md

@@ -63,3 +63,9 @@ playing. The stereo black box already works that way; nothing else does yet.
 - FLAC is 24-bit; SuperCollider output is float and could exceed 0 dBFS. Check peaks, or
   use a float container for the ring.
 - Window length N and the hard cap (disk floor is 25 GB, 100 GB is the keep-scratch line).
+- **Segment clocks (found cutting the first export, 2026-11-01).** Black-box segments after the
+  first hourly rollover carry `start_time=3600.x`, so `ffprobe duration` is the real length
+  plus an hour (a 6 min segment reported 66 min). `gig_record.sh slice` takes an offset from
+  the file start: the real length is `duration - start_time`. A cut computed from `duration`
+  alone lands past the end and writes 1 s of silence without an error. `moment` must use
+  `duration - start_time`, and check the output length against the request.