Live windows-latest proof settled it: a running Chrome opens its cookie DB
deny-all (even CreateFile with FILE_SHARE_READ|WRITE|DELETE fails; sqlite
mode=ro/immutable/nolock all 'unable to open'), so copy-while-running is
impossible on Windows without VSS/admin — and the prior code HUNG ~24min on the
locked file.
Fix: a fast up-front lock probe (_profile_is_locked: one open() of the active
profile's cookie DB; PermissionError = locked) runs BEFORE any copy in
snapshot_real_profile. If locked, bail immediately with 'fully quit the browser
(incl. background/tray) and retry, or turn browser.use_real_profile off'. Never
hangs, never a silent signed-out copy. POSIX has no mandatory locking so the
probe never trips there — copy-while-running still works on macOS/Linux.
Docs: admonition stating Windows needs the browser fully closed (background
apps included); the live-drive-while-running path is #95669.
Tests: lock-probe unit coverage (readable/no-db/PermissionError), snapshot
fails-fast-no-copytree when locked. Windows live E2E asserts the fast-fail
contract (returns <30s with the quit message) + the read-strategy diagnostic.
Teknium
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