Invalidate path-restriction cache when symlink realpath changes

[TheGreatAxios]

Summary

• Path-restriction cache entries retain the resolved target path and invalidate when a symlink retargets.
• Nonexistent targets resolve through their nearest existing ancestor before cache validation.
• A regression test covers an allowed workspace symlink retargeting outside the workspace.

Verification

• bun run check

Fixes CL-6708

[linear-code]

CL-6708

[TheGreatAxios]

Review · Comment

The path gate revalidates cached verdicts against the nearest-existing realpath before reusing them.

Findings

• CONTRIBUTING.md:100 — Commit 57280066 contains five body lines over the mandatory 72-character limit; git log origin/main..HEAD --format="%b" | awk "length > 72" returns each one. Could you rewrap the commit body so the branch history meets the repository rules?
• CONTRIBUTING.md:138 — The PR body uses Problem, Fix, and Test sections instead of the required Summary and Verification shape. Could you update it so the PR metadata follows the source-of-truth template?

Notes

• These findings should be resolved before merge; GitHub does not allow the PR author account to request changes on its own PR.
• bun run check exits 0 locally; GitHub build, lint, formatting, typecheck, and CLA checks are green.

[TheGreatAxios]

Review · Comment

The path-restriction cache invalidation branch now meets the repository metadata rules.

No findings.

Notes

• Commit 1897f0c7 wraps every subject and body line within 72 characters.
• The PR description uses the required Summary and Verification sections.
• bun run check exits 0 against the amended commit.

[TheGreatAxios]

Review · Blocking

The path restriction cache invalidates entries when a symlink's resolved target changes.

Finding

• src/permission/path-restriction.ts:204 — The cache records currentRealpath from one filesystem snapshot but pairs it with a verdict computed by a second resolution at line 219. If the symlink retargets between those calls, the cache can associate an unrestricted verdict with an outside realpath and reuse it later. Could we compute and cache the verdict from one resolved snapshot so the security decision and key cannot diverge?

GitHub CI is green, but this time-of-check/time-of-use window affects the permission boundary and should be resolved before merge.

[TheGreatAxios]

Review · No findings

The cache now derives validation, permission verdict, and storage from one resolved-path snapshot.

The deterministic retarget race and existing inside-to-outside regression pass, bun run check exits 0 with 5,897 tests, all required GitHub checks pass, and the prior blocking finding is resolved.