The val-Flat-collapse / Short-collapse / C51 expected-Q bias hypothesis
that motivated the 4-plan distributional-RL Thompson rollout was
largely a measurement artefact in the diagnostic infrastructure, not
a real policy pathology. Three layered bugs in actions_history_buf
init + reader + mag_stats attribution conspired to inflate val_dir_dist
Short, inflate active_frac, and pin wr_h/wr_f to zero. After fixing
all three (commits a86fba2b1 + b8788511c), val_dir_dist matches
val_picked_dir_dist within ~5pp — no collapse, diverse picks.
Status footer added to the spec documenting:
- what was actually wrong (3 measurement bugs)
- what the post-fix data shows (mild passivity bias from early
training, not a structural collapse)
- what is preserved (Phase 0 unit tests as latent infrastructure
for any future distributional Q-head; Aggregation Contract
pearl as a sound engineering invariant)
- what is cancelled (Plans B / C / D — Phase 1 audit, Phase 2
Thompson integration, Phase 3 long verification — superseded)
- future revival condition (if fresh L40S 30-epoch on post-fix
code shows val_picked_dir_dist itself collapsing toward Hold/Flat,
reopen)
Plan files remain in docs/superpowers/plans/ as historical record.
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