Add mode2_v1 schema — 73 pre-sliced clean segments from 27 source episodes (104.7 min, bad intervals excluded by construction). New ReactSegmentDataset + demo. No bad_frames.json filtering needed at the dataloader; data is constructively clean. mode1_v1 stays for backward compatibility. See segments.json + new README section.
Add per-episode GelSight reference images: episode_NNN.gs_ref_{left,right}.png = the 1st-percentile-intensity frame at native 640×480 (the 'quietest' / least-contacted moment of the episode). Use these as the diff baseline in any visualization — gives a stable 'this is what's currently pressing on the gel' diff rather than 'change since the start of this clip'. 27 episodes × 2 sides = 54 files.
Trim OT-uninitialized prefixes from 3 .pt files (ep_005/012/017 — see `_contact_meta.trim_offset`); recompute bad_frames + data_quality_breakdown in trimmed coords; ot_loss frame count now reflects real mid-episode mocap dropout only. Recorder-side OT watchdog added to data_collection.py (in twm repo) so future episodes won't repeat the bug.
