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X11's original plan said "capture_graph_a covers full v2 forward" but
the X11 commit (4f888abbf) only shipped forward_only + from_checkpoint.
Graph capture is now actually implemented for the inference path.
Mirrors the pattern already in step_batched (perception.rs:1221-1257):
- First call: eager dispatch + set forward_warmed flag.
- Second call: begin_capture -> dispatch_forward_kernels -> end_capture
-> store CudaGraph.
- Subsequent calls: graph.launch() — captured replay.
forward_only now performs its own staging-fill of the mapped-pinned
host buffers (input data varies per call), then dispatches through
the three-state machine. The captured region is the new private
dispatch_forward_kernels helper: a copy of evaluate_batched's
forward chain (VSN -> Mamba2 x2 -> LN x2 -> attn-pool -> CfC K-loop
-> heads) that omits labels, BCE, and any stream syncs. The final
sync + dtoh of probs_per_k_d happens OUTSIDE capture in forward_only.
Per pearl_no_host_branches_in_captured_graph: no host branches /
scalar-arg-changes / host-mallocs inside the captured region; all
kernel launches use pre-bound device pointers stable across replays.
Per pearl_cudarc_disable_event_tracking_for_graph_capture: event
tracking is already disabled for the trainer's lifetime at
construction (see PerceptionTrainer::new ~line 529), so the captured
region is free of cuStreamWaitEvent / event.record() insertions.
Vestigial loader.rs:272 doc comment referencing the never-shipped
CfcTrunk::capture_graph_a updated to point at the now-real
PerceptionTrainer::forward_only warmup path.
Regression: forward_captured_matches_uncaptured — eager (call 1) vs
captured replay (call 3) agree within 1e-5 relative tolerance per
element. NOT strict bit-identity because CUDA Graph capture can
reorder kernel launches and flip f32 reductions by 1 ULP harmlessly.
Local RTX 3050 Ti run: 160 elements, max rel_err = 0e0.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
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