E2E diagnostic was precise: "finish TIMEOUT processed=78/79", submit_failed=0 —
the per-layer notifier fires 78x but kv_data_ptrs has 79 layers (the 79th is the
MTP/nextn EAGLE buffer: present in kv_data_ptrs so the monolithic send moves it,
but it doesn't fire the per-layer hook). The old completion required all num_layers,
so it both hung to the timeout AND would silently miss that layer's KV (corruption).
Redesign: gate completion on the ACTUAL enqueued count (note_enqueued), and in
finish() SYNCHRONOUSLY transfer any layers the notifier didn't fire for (KV is fully
written post-forward, no event needed). Net: the per-layer set == kv_data_ptrs,
byte-identical to the monolithic send; robust to any model firing fewer hooks than
KV buffers. The fired layers stay overlapped with the forward.
Unit tests updated (25 pass): fallback transfers the missed layers; submit failures
still report -1.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
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