Phase E.1 Task 10. Standalone target-augmentation kernel:
m = α_m · max(τ · log π(a|s), log_clip_min)
V_soft(s') = max(Q_next) + τ · log Σ exp((Q_next − max) / τ)
target = r + m + γ · V_soft(s') (terminal: r + m)
π(a|s) ∝ exp(Q_online(s, a) / τ) — softmax policy from the online net.
Munchausen bonus is implicit KL regularisation between successive policies;
soft-V replaces the hard max bootstrap with a τ-weighted softmax average.
Both softmaxes are computed via log-sum-exp with the max-trick. This is
essential at τ ≈ 0.03 where raw exp(Q/τ) would overflow f32 for any
Q-spread > 25 nats. The kernel is one-thread-per-batch-sample, no
atomicAdd, no host branches.
α_m, τ, log_clip_min are kernel args (not hard-coded), so a Phase E.2+
controller can ISV-drive them. Typical Vieillard values: α_m=0.9, τ=0.03,
log_clip_min=-1.0.
Does NOT touch any ISV slot — pure target augmentation.
Cubin: target/release/build/ml-*/out/phase_e_munchausen_target.cubin (12.8 KB).
Launcher integration is Task 11 (consumes target_out where the C51/MSE
loss kernels currently consume `r + γ · max_a' Q_target`). Audit doc
docs/isv-slots.md updated per Invariant 7.
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