Atomic removal of 5 boolean feature flags from DQNConfig per
`feedback_no_feature_flags.md`, all of which gated dead or redundant code.
(use_iqn already removed in da632446c.)
- `use_dueling`, `use_distributional`, `use_noisy_nets`, `use_branching`:
pure-cosmetic always-on flags. Only metadata strings remained.
4 `if true /* always on */` blocks in dqn.rs collapsed to live arms;
dead else arms (legacy non-branching code paths, 5-flat ExposureLevel)
deleted.
- `use_count_bonus`: redundant with `count_bonus_coefficient` (the live
numeric kill-switch). Recording made unconditional; coefficient is the
single dial.
- `use_cvar_action_selection`: dead post-use_iqn cleanup (only consumers
were inside the deleted IQN arms). cvar_alpha retained for cuda_pipeline
CVaR loss usage.
count_bonus.rs API tightened: `bonuses_branched_f32(&self,
exp_out: &mut [f32], ord_out: &mut [f32], urg_out: &mut [f32])` write-into
API alongside the existing Vec<f64> form (kept for tests). Production
DQN::get_count_bonuses_branched() returns fixed `([f32; 4], [f32; 3],
[f32; 3])` arrays — allocation-free, f32 throughout, fed directly to GPU
action selector via stack-allocated buffers.
Test 0.F outputs bit-identical vs pre-cleanup (sigma_C51, argmax,
Thompson counts) — confirms legacy use_* arms were unreachable as
expected.
`docs/dqn-wire-up-audit.md` updated per Invariant 7.
Precondition for the MoE regime redesign per
`docs/superpowers/specs/2026-04-27-moe-regime-redesign-design.md`.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
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