Add BlockService replica-side rebuild routing API that bridges
transport/host layer to BlockVol session surface:
StartReplicaRebuildSession(path, config)
ApplyReplicaRebuildWALEntry(path, sessionID, entry)
ApplyReplicaRebuildBaseBlock(path, sessionID, lba, data)
MarkReplicaRebuildBaseComplete(path, sessionID, totalBlocks)
TryCompleteReplicaRebuildSession(path, sessionID)
CancelReplicaRebuildSession(path, sessionID, reason)
ReplicaRebuildSession(path) → snapshot
Each method does one thing: validate → WithVolume → delegate to BlockVol.
No wire decoding, no protocol decisions, no state invention. Transport
wiring (sessionControl/walData/sessionData handlers) is the next step.
2 focused tests: skeleton routes correctly, stale session ID rejected.
Updated v2-rebuild-mvp-session-protocol.md with server skeleton section.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>