forward_only requires the full K=seq_len window on every call and resets
Mamba2 h_s2 to zero each invocation — no cross-call state carry. Additionally,
the call is inside the stride=200 gate in harness.rs (spec §3.2 claim "already
every event" is incorrect as of HEAD). Moving to stride=1 without a forward_step
implementation would be a ~200x GPU cost increase. A0.5 must implement
forward_step with persistent h_s2, a dedicated K=1 CUDA graph, and session-reset
hook. Memo documents exact file paths, line numbers, required struct/method
changes, and open questions for the A0.5 implementer.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
