HOT site at simulate_batch_gpu — `actions: &[i32]` was uploaded
per-batch via stream.memcpy_htod into a persistent CudaSlice. Promoted
the field to `MappedI32Buffer` allocated once at constructor; per-call
host writes now go through `host_ptr` (no HtoD copy). Kernel arg switched
to passing `dev_ptr` as a u64.
The two COLD sites (ctor init_state, reset init_state) writing into the
GPU-mutated `portfolio_state_buf` cannot replace the destination buffer
type (env_step kernel writes back to it). Use a mapped-pinned staging
buffer + memcpy_dtod_async via a new `upload_portfolio_state` helper.
Retains zero direct HtoD copies on the only path the violation rule
permits per `feedback_no_htod_htoh_only_mapped_pinned.md`.
Sites migrated:
- L122 ctor init_state (htod_f32 -> staging+DtoD via upload_portfolio_state)
- L174 simulate_batch_gpu actions upload (HOT: persistent MappedI32Buffer)
- L296 reset init_state (htod_f32 -> staging+DtoD)
Audit doc: docs/dqn-gpu-hot-path-audit.md updated with new MIGRATED entries.
cargo check -p ml --lib: 13 warnings, baseline preserved.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
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