spec_vault swept every file under a book, lock files included; on Windows a held LockFileEx lock is mandatory and the read failed. The locks are already dedicated files (never data), so the test skips *.lock. Merged main (P13 step 6, the macOS server.log assert, P11a's AppImage identity): host.rs keeps main's five-field identity on Unix and size/last-write on Windows; the update poll and set_program_version are Unix-only. Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01HS8WZziDnyxunC23MUxrLp