First half of Phase C. Lands the producer side of the K=3 trade-
outcome aux head's state bridge: new kernel populates a per-env
3-slot cache from the K=3 softmax tile every rollout step. The
consumer side (state gather reading from this cache → state slots
[121..124)) lands in Phase C-2.
Mirrors the K=2 head's existing aux_softmax_to_per_env_kernel exactly
at K=3:
- K=2: prev_aux_dir_prob[env] = 2*softmax[env, 1] - 1 (recentered)
- K=3: prev_aux_outcome_probs[env, k] = softmax[env, k] for k in [0, 3)
Changes:
- state_layout.rs: 3 new constants AUX_OUTCOME_PROFIT_INDEX = 121,
AUX_OUTCOME_STOP_INDEX = 122, AUX_OUTCOME_TIMEOUT_INDEX = 123.
PROFIT_INDEX aliases AUX_DIR_PROB_INDEX (same value, different
semantic). Phase C-2 flips slot 121's meaning from K=2's recentered
p_up to K=3's p_Profit.
- aux_outcome_softmax_to_per_env_kernel.cu: new kernel + cubin.
- gpu_dqn_trainer.rs: new SP22_AUX_OUTCOME_SOFTMAX_TO_PER_ENV_CUBIN
embed.
- gpu_experience_collector.rs: 2 new struct fields (cache buffer +
kernel handle); cubin load + alloc in constructor; struct-init;
per-step launch in rollout loop after K=3 forward.
- build.rs: kernel registered.
Encoding shift K=2 → K=3: K=2 used recentered [-1, +1] to match
"no signal = 0" baseline of every other slot. K=3 keeps raw softmax
probabilities [0, 1]. Cold-start sentinel 0.0 for all 3 slots =
"no prediction yet" (mask). The 3-slot natural distribution is more
informative than a scalar.
Dead-code status: producer populates cache every step but
experience_state_gather doesn't read from it yet — state slot 121
still receives K=2's prev_aux_dir_prob write. Phase C-2 swaps the
state gather's source from K=2 cache to K=3 cache (3-slot write).
Why split C into C-1 + C-2: experience_state_gather is a hot-path
kernel with many consumers. Updating it touches training collector,
eval-side backtest evaluator, Rust launcher arg list. C-2 lands that
as an atomic state-semantic flip; C-1 lands the GPU-side scaffolding
independently so the producer chain can be validated first.
Verification:
- cargo check -p ml clean.
- cargo test -p ml --lib → 1016/0 green.
Audit: docs/dqn-wire-up-audit.md Phase C-1 section.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
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