Task 2.0 instrumentation (commits d60e5375a / 980f3b07f / 41b0c559c)
revealed two silent bugs in Task 0.4's grad_ratio_mag_dir accessor:
Bug A — readback size mismatch: pinned buffer allocated at
total_params, but grad_buf length is total_params+cutlass_tile_pad,
so size check always failed → Err silently coerced to 0.0 by proxy.
Bug B — readback timing wipe: estimate_avg_q_value_with_early_stopping
in process_epoch_boundary replays the forward graph, which zeros
grad_buf. Any subsequent readback sees all zeros.
Both fixed in 41b0c559c; snapshot hoisted to top of process_epoch_boundary.
With those bugs fixed, the measured gradient ratio is NOT 0.0000 — it is
50–400× mag/dir across 60 epochs. Magnitude branch is over-fed, not
starved. Direction gradient is small but non-zero (~2e-2 to 7e0).
Direction policy is observably healthy (Short/Hold/Long/Flat 38/12/42/14%).
Track 1 triage's H4 CONFIRMED verdict was a measurement artefact
produced by Bugs A+B. H4 as originally defined is now REJECTED.
Plan changes:
- Add new "Task 2.0 findings" section after cross-cutting concerns,
documenting bug A, bug B, observed data, and revised strategy.
- Task 2.1 marked DEFERRED (not deleted — kept for reference).
- Task 2.2 promoted to PRIMARY fix.
- New fallback: H9 delete-magnitude-branch as replacement for Task 2.1
if Task 2.2 alone is insufficient.
- Task 2.0 inventory row updated with LANDED status and commit chain.
Net effect: Phase 2 simplifies. The hardest task (2.1 three-branch
architectural fix) is skipped; primary path is Task 2.2 (~25 LOC).
7e78bf4f85