_augment_tracks gated the object-coverage + low-rank-weighted + uniform draw on
`0 < max_points < N`, so with the default WANTRACK_MAX_POINTS=2500 and the full
2500-track grid (max_points == N) the entire subsample block was skipped -- the
model saw all 2500 tracks every step and only chunk-masking ran. Gate on
`min_points < N` instead so K~U[1000,2500] actually samples (verified: kept
1179/1437/1573 across steps, was a constant 2500).
Also: TrackValidation now applies the same sampler (loads object_ids/track_weights,
runs _augment_tracks deterministically) so validation is conditioned on -- and
overlays -- the sampled subset, not the full grid. Env-gated WANTRACK_DEBUG=1 logs
per-step sampling stats (kept count, object coverage, coord ranges). Adds a
single-video (golf) overfit config for debugging.
shaoxiongduan
c6d0233eab