Per-horizon P(up) at h ∈ {30, 100, 300, 1000, 6000} snapshots forward.
Single-block 5-thread kernel; each thread is its own 128-dim dot
product + sigmoid. No atomicAdd.
Tests (5/5 pass on sm_86) assert invariants only:
- sigmoid output ∈ [0, 1] for all heads
- zero weights + zero bias → 0.5 exactly
- bias = +20 → saturates near 1
- bias = -20 → saturates near 0
- per-head independence (mixed-bias configuration)
Addendum updated to explicitly state no-CPU-mirror discipline per
feedback_no_cpu_test_fallbacks.md.
Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
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