The windows-native job has been red since #1990 put the sandbox-windows-acl sources into the Windows 100%-per-file denominator without tests carrying them, and #1543 dropped the authoring.ts V8 ignore for the POSIX-only owner-execute branch. Non-blocking at merge time, the red state has propagated to every later pull request.
Cover every in-process ACL-sandbox failure branch with stub-based failure-path suites (ffi/acl/token/spawn/index), following the package's existing failure-paths pattern; the package now measures 100% per file under the Windows denominator. Exclude only the runner entry from the win32 denominator: it executes exclusively as a spawned child outside the instrumented run, and its behavior is pinned end-to-end by the runner suite. Restore the authoring.ts narrow V8 ignore and add one for the dispose token guard whose absent-token arm is lifecycle-unreachable. Update the dual-lane Agent Note with the denominator composition.
Durable record: bound to the owning session id and validated at the fold (orphan-SID shape, temp path inside the host temp root) — a fork's copied parent record no longer provisions the child, and a tampered record fails loud. Private temp dir: random unguessable name persisted in the record, created exclusively (pre-existing entries and reparse points fail EEXIST). Persistence: a fresh provision kicks an immediate flush (no write-behind debounce), narrowing the crash window to the flush latency — documented as the one self-healing gap. Runner-failure rules: exit-gated on 127 so a confined command that prints the signature on a non-127 exit is never misclassified. Spawn: AssignProcessToJobObject failure terminates the suspended child (no hanging orphans). SandboxExecutionPolicy.sessionId is the branded SessionId. Boundary docs: qualifying clause on the absolutist sentences, NULL-DACL Known Limitation, 'full' scoped to the supported NTFS surface, CLM gate comment.
quoteArg doubles end-of-string backslashes (real CommandLineToArgvW round-trip test; first-token exemption noted); grantWrite merges into the current DACL instead of replacing it, and both grant/revoke hold a LockFileEx per-path lock under GetTempPathW/dsh-acl-locks (koffi crashes on NULL lpOverlapped — a zeroed OVERLAPPED is used); GRANT_MASK gains DELETE|FILE_DELETE_CHILD (never WRITE_DAC/WRITE_OWNER) though the win32 26200 second check only constrains the WRITE bit; failure paths close all handles (CreateProcessAsUserW pipe set, ResumeThread thread/process/job) with stub-api tests; getTempPathW refuses undersized buffers; drainPipe backs off; runner.spec pwshAvailable uses the resolvePwshPath probe; NTSTATUS exit codes mirror bit-exact (verified end-to-end); WinLocalSid JSDoc re-attributed to WinLocalLogonSid. All gates green: 42 passed/2 skipped, typecheck, oxlint, 0 clones, constraints, knip.
