Vendored npm rollback / remove / vendor --revert on a lockfileVersion 2 lock fail after any npm install, yet half-revert the lock: packages goes back to the registry while the legacy mirror keeps the patched integrity, and npm 6 then fails EINTEGRITY #1937

[agent] Found by the scheduled npm bug-hunt routine (ledger #302).

Summary

This is the revert-side sibling of #879. After a vendored scan of an npm lockfileVersion 2 project, an ordinary npm install (npm 7, 8, 10 or 12 on an existing v2 lock) re-saves the lock. npm never writes resolved for a file: resolution in the legacy dependencies mirror, so the mirror node keeps only version and the patched integrity. #879 taught vex and vendor --check that this is still wired, and both pass on main. The revert engine wasn't updated:

• rollback, remove <purl> and vendor --revert warn vendor_lock_entry_drifted "lock entry /dependencies/left-pad was re-resolved since vendoring (no resolved field); left alone" and keep the vendored state. rollback and remove exit 1. rollback --json reports rollback_failed: "nothing was rolled back: 1 patch failed", with the event "lockfile wiring drifted; vendored state left untouched".
• That claim is false: the same run did rewrite the packages["node_modules/left-pad"] entry back to the registry resolved and integrity. The mirror node still carries the patched integrity. The lock is left half-reverted, and the ledger plus .socket/vendor/ artifact are kept.

Impact

• Every npm 7/8 team, and every npm 9–12 team with an existing v2 lock, that vendors a patch and then runs npm install once can no longer roll it back or remove it with one command. That's the normal workflow: the scan's own "Next steps" tells them to run npm install.
• The failed run leaves a lock that no longer matches itself. npm 7+ npm ci installs the upstream bytes from packages. npm 6 reads the mirror and fails npm ci with EINTEGRITY (wanted sha512-<patched> but got sha512-<registry>). After that, vendor --check exits 1 ("vendored wiring drifted … node_modules/left-pad still resolve left-pad@1.3.0 outside the vendored artifact"), even though the user asked for the patch to be removed.
• The remedy it prints ("undo the drift … or re-vendor, and re-run vendor --revert") does work: scan --mode vendored re-adds the mirror resolved, and a revert then succeeds. But it means re-vendoring a patch you're trying to remove, and the next npm install before the revert brings the problem back.

Repro (Linux, Node 22.23.4, npm 8.19.4; a local mock patch API serving one free patch for the real npmjs left-pad@1.3.0)

mkdir p && cd p && git init -q
echo '{"name":"p","version":"1.0.0","private":true,"dependencies":{"left-pad":"1.3.0"}}' > package.json
npm install                                   # npm 8 → lockfileVersion 2
socket-patch scan --mode vendored --yes $API  # exit 0; both packages entry and mirror get resolved file:.socket/vendor/...
git add -A && git commit -qm vendored
rm -rf node_modules && npm ci                 # patched
npm install                                   # re-saves the lock: drops `resolved` from dependencies.left-pad (git diff: 1 deletion)
socket-patch vendor --check                   # exit 0 (fixed by #879)
cp package-lock.json before.json
socket-patch rollback; echo $?                # exit 1: "Kept vendored state …: lockfile wiring drifted; vendored state left untouched"
diff <(jq . before.json) <(jq . package-lock.json)
#  packages["node_modules/left-pad"].resolved:  file:.socket/vendor/npm/<uuid>/left-pad-1.3.0.tgz → https://registry.npmjs.org/left-pad/-/left-pad-1.3.0.tgz
#  packages["node_modules/left-pad"].integrity: sha512-<patched> → sha512-<registry>
#  dependencies.left-pad: unchanged (version + PATCHED integrity, no resolved)
ls .socket/vendor/state.json                  # still there
npx npm@6 ci --cache "$(mktemp -d)"           # EINTEGRITY wanted sha512-<patched> but got sha512-<registry>
socket-patch vendor --check; echo $?          # 1: vendored wiring drifted

remove pkg:npm/left-pad@1.3.0 (exit 1, "1 matching entry was drift-kept … re-run scan --mode vendored to normalize, then remove again") and vendor --revert (exit 0, "Kept 1 drifted package") leave exactly the same half-reverted lock.

Expected vs actual

• Expected: a mirror node with no resolved and the recorded vendored integrity is treated as ours (Vendored npm vex and vendor --check fail after any npm 7–10 npm install on a lockfileVersion 2 lock, because npm drops resolved from the legacy mirror and #813 treats that as an unpatched npm 6 install (regression) #879 already established that this is npm's normal serialization, and vex / vendor --check accept it), so the revert restores both the packages entry and the mirror and exits 0. At the very least, when one record of a package is drift-kept, none of that package's records should be rewritten. Per CLI_CONTRACT.md, an explicit reversal (rollback, remove, vendor --revert) undoes the vendoring, and the event text says "vendored state left untouched".
• Actual: exit 1 (rollback / remove) with "nothing was rolled back", while the packages entry was rolled back. The result is a half-reverted, self-inconsistent lock.

Matrix (Linux only: probe branches are still paused for this routine)

Same result on main cbbbdb9 and the v5.0.1 release, so it isn't a recent regression. It has probably been there since the npm mirror revert records were added; I didn't bisect further.

Suspect code

• crates/socket-patch-core/src/vendor/npm_lock.rs:1365: let ours = match live_resolved { … None => false }. For a KIND_LOCK_LEGACY_ENTRY record, a missing resolved should count as ours when the live integrity equals the recorded vendored (rec.new) integrity, the same rule Vendored npm vex and vendor --check fail after any npm 7–10 npm install on a lockfileVersion 2 lock, because npm drops resolved from the legacy mirror and #813 treats that as an unpatched npm 6 install (regression) #879 added to vex/discover/npm.rs (drop_mirror_unwired).
• The revert applies the package's other records (the packages entry) before the drift verdict, then crates/socket-patch-cli/src/commands/rollback.rs:1029 reports "vendored state left untouched". The per-package keep decision should either gate every record of the package or be reported as a partial revert.
• The unit test at npm_lock.rs ~4910 (resolved-less entry left alone) pins the drift verdict for a packages entry. A mirror-node twin of that test with the vendored integrity should expect a clean revert.

Related: #879 (the same npm serialization on the check/vex side, fixed), #1155 / #1187 (version-moved-off drift-keep for npm), #989 (the revert-engine tracking issue).