[TheGreatAxios]

What changed

• New tooling/vendor-diff-pruned.txt: only the upstream paths a re-vendor excludes, 46 entries (32 directory prefixes, 14 exact files where the parent directory is partly vendored), generated once from the current diff as the shortest ancestor of each missing stock path that holds nothing vendored.
• tooling/vendor-diff-check.sh:
  • A stock path missing from vendor/interchange stays informational only when it, or a directory above it, is listed. Any other missing path fails with D <path>, unless exactly allowlisted like any other drift.
  • A pruned entry fails when it covers a path in the vendored tree at HEAD (covers vendored <path>: <entry>), or covers no missing stock path, such as a directory written without its trailing / (covers no missing stock path: <entry>). These failures get their own advice: remove or narrow the entry.
  • Drift failures keep their advice: revert toward stock, or record an upstream-justified allowlist entry.
  • The header comment says missing stock paths matching a pruned entry exactly or as a directory prefix are excused, and the pass line names both files.
• vendor/interchange/VENDORED.md: absent upstream paths are informational only when listed in the pruned list, and a re-vendor whose excluded paths change updates it. The file is excluded from the gate.
• docs/ARCHITECTURE.md (Vendoring) describes the list.

Verification

Against the pinned stock commit, fetched from upstream:

• Clean tree: exit 0, informational: 5125 upstream paths are absent from the pruned checkout.
• Temporary packages/hub-client/ entry: exit 1, covers vendored … lines and covers no missing stock path: packages/hub-client/.
• Temporary dead entry (tests/workflow/ written as tests/workflow): exit 1, the files under it fail as D, and covers no missing stock path: tests/workflow.
• packages/hub-client/src/transforms.ts deleted and committed: exit 1, D packages/hub-client/src/transforms.ts.
• There is no case script for this gate.

Closes CL-11456

[linear-code]

CL-11456

[corbits-triage]

Triage: Pass

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