When use_noisy_nets=true (the conservative() default), epsilon never
decayed from 1.0 because (1) the trainer skipped update_epsilon() and
(2) DQNAgentType::set_epsilon() was a no-op for RegimeConditional agents.
This caused ALL training actions to be random — Q-values were learned but
never used for action selection.
Fix: set stored epsilon to 0.0 at training start when noisy nets are on.
Exploration is provided by NoisyLinear weight perturbation + the separate
noisy_epsilon_floor (5% safety floor for 45-action spaces).
Also fixes:
- Zstd-compressed .dbn file detection via magic bytes (0x28B52FFD)
- Test data path resolution using ancestors().find() for workspace root
- Test assertions updated for epsilon < 0.01 with noisy nets
2698 lib tests pass, 0 clippy warnings.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
7ab5d4fa71