Extends backtest_env_step + backtest_env_step_batch kernel signatures
with 6 new NULL-tolerant args for per-trade tape emission:
- float* per_trade_pnl_out
- unsigned int* per_trade_holding_bars_out
- unsigned int* per_trade_bar_index_out
- unsigned int* per_trade_dir_mag_out (packed hi-16 dir, lo-16 mag)
- unsigned int* per_trade_count
- int max_trades_per_window
Each kernel snapshots entry_price + hold_time BEFORE the
unified_env_step_core call, then post-call mirrors
record_kelly_trade_outcome's close-detection predicate
(is_exit || is_reversal with positive entry_price + valid pre-trade
equity guards) to recompute the realized return for per-trade tape
emission. Single thread per window writes its own slot — race-free
counter increment without atomicAdd per feedback_no_atomicadd.
Step A only — Step B (host alloc + readback + enrichment integration)
follows in a separate commit. This commit is the kernel ABI extension
with NULL launchers, bit-identical to pre-Phase-1 behavior.
NULL-tolerant ABI extension is the codebase's canonical phased-rollout
pattern. Same shape as alpha_per_env / is_win_per_env additive contracts
in sp20_aggregate_inputs_kernel. Per feedback_no_partial_refactor's
"consumer migrates with contract change" rule, the consumer (launcher)
MIGRATES here by passing NULL — output behavior preserved bit-identically.
Step B (next commit):
- Allocate per-trade buffers in GpuBacktestEvaluator constructor
- Pass real device pointers from launcher
- Reset per-window counter at fold start
- Host-side readback into Vec<EvalTrade>
- Wire to enrichment caller, replace extract_eval_trades_from_metrics
Affected files:
- crates/ml/src/cuda_pipeline/backtest_env_kernel.cu (both kernels)
- crates/ml/src/cuda_pipeline/gpu_backtest_evaluator.rs (both launchers)
Verification:
- cargo check -p ml --tests: passes (warnings only)
- GPU oracle tests: NULL-tolerance contract preserved by construction
(per_trade_count == NULL gates the entire emission block)
Plan reference: docs/plans/2026-05-10-sp21-train-eval-coherence-isv-defrost.md
T2.2 multi-phase scope section.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
5d01190e19