The prior `test_eval_action_select_boltzmann_bounded` asserted
Boltzmann theory (P(best)≈0.366 at tau=q_range) on the direction
branch. Plan C T2 (commit 52a2663a2) replaced the direction-branch
Boltzmann path with single-distribution C51 Thompson + argmax-E[Q]
eval; the T2 amendment (5de5e546a) added 4 args to the kernel ABI
(b_logits_dir, per_sample_support, atom_positions, n_atoms). The old
test was launching with an outdated arg count and asserting a
distribution shape that no longer applies.
Migration (per feedback_no_partial_refactor):
- Rename to `test_eval_action_select_eval_argmax_picks_best`
- Build per-direction C51 logits PEAKED at distinct E[Q] values:
Short=-0.5, Hold=-0.1, Long=+0.5 (best), Flat=+0.1
- Linear adaptive support [v_min=-1, v_max=+1, delta_z=0.1] uniform
across all (sample, direction) pairs
- Run kernel in eval mode (eps_start=eps_end=0): assert P(Long)>=0.99
i.e. the kernel deterministically picks argmax(E[Q]) per sample
This validates the T2 amended ABI runs end-to-end and exercises the
production kernel's argmax-E[Q] eval branch with a controlled
distinct-E[Q] setup. Companion to Phase 2 Tests 2.A-2.D in
distributional_q_tests.rs which add training-mode assertions and
production-vs-standalone parity checks.
Verification: `SQLX_OFFLINE=true cargo check -p ml --lib --tests` clean.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
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