Three bugs causing the baseline RL training to hang on first epoch while
smoketest completes in 1.2s:
1. VRAM oversubscription (hang root cause): detect_gpu_hardware auto-scaling
computed n_episodes without accounting for 2x counterfactual doubling or
dtod_clone allocations, causing 4x actual memory vs budget. Replaced with
configurable gpu_n_episodes field (smoketest=32, localdev=128, prod=4096).
2. Counterfactual experiences silently dropped: build_next_states_f32 received
n_episodes instead of n_episodes*2, and PER insert used base count instead
of doubled count — ~50% of augmented training data was generated then lost.
3. CudaEvent leak in hot loop: record_event(None) created+destroyed 8000 events
per epoch in forward_online_raw/f32. Pre-allocated 4 events in CublasForward
struct, eliminating driver overhead and handle leaks during CUDA Graph capture.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
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