fix: preserve exact multiscan lock identities

[mldangelo-oai]

Summary

Prevent failed multiscan owner publication from removing a replacement supervisor's empty lock directory when distinct large file IDs round to the same JavaScript number.

Changes

• Read both lock-directory identities with lstat(..., { bigint: true }) before deciding whether cleanup owns the directory.
• Extend the existing replacement-lock tests with distinct inode IDs that collide as numbers. Keep empty and published replacement cases separate, and isolate the filesystem spies in subprocesses.
• Preserve the existing cleanup of an empty lock owned by the failed supervisor.

Testing

Using Bun 1.3.14:

• bun test --timeout 30000 --seed 1 --test-name-pattern 'owner creation fails' ./tests-ts/multiscan.test.ts: before the fix, two cases passed and the empty-replacement case failed with ENOENT; after the fix, all three passed.
• bun test --timeout 30000 --seed 1 ./tests-ts/multiscan.test.ts: 50 passed, zero failed.
• pnpm run types, pnpm run format, and git diff --check: passed.
• Three fresh native reviews and independent verification of 0cc84eca: no findings.

The full supported-runtime CI matrix, including Windows and installed-package checks, passed on this exact commit.

Risk and rollout

The production diff changes only the two identity reads in failed-owner cleanup. Lock leases, owner records, heartbeat behavior, and cleanup error handling are unchanged. This uses the same bigint stat API already used by the CLI. There are no public API, dependency, package-format, or migration changes.

Public disclosure review

• No customer, partner, prospect, or user identities, data, or identifying details are included.
• No credentials, personal data, private source, scan findings, or nonpublic links or tickets are included.
• I reviewed the branch name, title, description, commits, changes, comments, logs, screenshots, attachments, and links for public disclosure.

[mldangelo-oai]

@codex review

Please review exact head 0cc84eca3f1575d1c5213425be8092a77d01ba3d. The production change is limited to exact bigint identity reads during failed multiscan owner-publication cleanup. The regression uses synthetic colliding numeric inode IDs and verifies both empty and published replacement locks.

[mldangelo-oai]

@codex security review

Please review exact head 0cc84eca3f1575d1c5213425be8092a77d01ba3d, especially preservation of replacement-lock ownership and the unchanged cleanup lifecycle.

[chatgpt-codex-connector]

Codex Review: Didn't find any major issues. 👍

Reviewed commit: 0cc84eca3f

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