[Diffusion] Register HWR mmap for direct DLO H2D (#6591)

Signed-off-by: Hongsheng Liu <liuhongsheng4@huawei.com>
Signed-off-by: hsliuustc0106 <hsliuustc0106@users.noreply.github.com>
Co-authored-by: hsliuustc0106 <hsliuustc0106@users.noreply.github.com>

docs/design/module/host_weight_runtime.md

@@ -16,7 +16,7 @@ validation_paths:
   - tests/host_weight_runtime/**
 upstream_refs:
   - https://github.com/vllm-project/vllm-omni/issues/6414
-last_reviewed: 2026-08-21
+last_reviewed: 2026-08-25
 ---
 
 # Host Weight Runtime
@@ -84,6 +84,13 @@ another. `WeightArtifactIdentity` includes:
 - producer version, implementation fingerprint, manifest schema, and restorer
   schema.
 
+Loader integrations may persist content digests for canonical source shards in
+the selected storage domain. Reuse requires the same path, inode, size,
+timestamps, symlink target, and cache-record checksum. Corrupt records are
+rebuilt, and coordination or cache-I/O failure falls back to hashing the
+canonical source directly. This is an identity-computation optimization, not a
+second source of truth or an artifact substitution rule.
+
 The identity excludes transfer policy such as registered mmap versus private
 pinned staging. Those paths move the same host representation and must not
 produce duplicate artifacts.
@@ -237,6 +244,12 @@ Every publication computes full file and tensor hashes. Local lookup supports:
   and
 - `full_checksum`, which additionally reads and hashes every payload file.
 
+An ordered producer may compute file and tensor digests while payload bytes are
+written and overlap each closed payload's `fsync` with later producer work. An
+unordered producer retains parallel readback hashing. In both cases manifest
+and `READY` publication wait for every payload digest and `fsync`; the atomic
+publication and validation contract is unchanged.
+
 Filesystem verity is modeled but unsupported. Invalid artifacts receive an
 external deny marker before their shared lookup lock is released; a build owner
 then quarantines the immutable directory under the exclusive lock.