Decide: should hosted VEX require installed evidence by default instead of attesting from lockfile wiring? #1099

[agent] Filed by the scheduled architecture audit routine (ecosystems and formats). Register: register comment.

Kind: decision. Source: review §6 Q4; 2.2; 6.5; register E46.

Question

When vex finds no installed copy of a hosted-patched package, should it still attest not_affected from the lockfile wiring (a Socket-host reference plus an integrity pin)? Or should that "lockfile basis" become opt-in, so that the default requires installed bytes that verify?

Options

• A. Keep today's default. The lockfile basis attests whenever no installed copy is found. Keep fixing package-manager quirks one at a time.
• B. Installed evidence by default, lockfile basis opt-in. Standalone vex attests a hosted purl only when its consumed copies verify. A flag (for example --allow-lockfile-basis, or --evidence wired) restores today's behavior for lock-only CI checkouts. In-run scan --mode hosted --vex keeps its existing in-run exemption for the purls that run confirmed, which is a separate code path.
• C. Keep the default, but mark it. Attest from the lockfile basis, but say so in the statement: for example "(redirected, not installed)" in the impact statement, or a distinct status_notes. A consumer can then filter it, and the JSON envelope reports a separate count. This could be combined with A or B.

The audit recommends B + C: opt-in wiring evidence, labelled when used. B is user-visible: it changes the vex output on lock-only checkouts and the documented "before installation" behavior in docs/usage.md. That is why this needs an owner decision.

Background (main @ e61a845)

• The basis: PatchedRef::lockfile_basis_ok holds for a hosted ref whose lock pins integrity, or whose format needs no pin.
• What it excuses: vex turns a package_not_found failure into applied for those purls (commands/vex.rs#L691-L703). The guards are: not mirror-refused, in --ecosystems scope, and the pnpm store not hidden.
• The statement doesn't say so: the statement is the same as for installed-and-verified bytes. Every hosted statement reads "Patched via Socket patch (redirected)" (vex/build.rs#L90).
• Why it misfires: "no installed copy found" means "the crawler found none", not "the package manager installs none". Every layout the crawler doesn't model turns into an absence, and the lockfile basis then attests over it.
  • Examples fixed one at a time: npm crawler never looks in Rush's common/temp store: hosted vex attests a transitive dep not_affected while its installed copy is unpatched, and agent apply reports it package_not_installed #518 (Rush store), Hosted pnpm vex attests not_affected over an unpatched install when pnpm's modulesDir is set (pnpm 10.12+), because the missed install is treated as "nothing installed" #696 (pnpm modulesDir), Hosted gem VEX attests not_affected for an unpatched install when .bundle/config sets an out-of-tree path (absolute or ~/…), because the skipped bundle root counts as "nothing installed" #709 (an out-of-tree bundle path), With Bun's isolated linker, vex attests a hosted patch as not_affected (verified) while the installed copy under node_modules/.bun is still unpatched (v5 regression) #405 (Bun isolated linker).
  • Open examples: In a yarn classic Plug'n'Play project, vex attests a hosted patch as not_affected while the copy .pnp.js loads is still unpatched #519 (yarn PnP), Hosted npm pin in package-lock.json is attested by VEX in a Deno project, but deno.lock keeps installing the unpatched registry copy #406 (deno.lock), Global Go patching (-g) reports success and VEX attests not_affected, but tools already built with go install keep running the unpatched code, and nothing tells the user to reinstall them #422 (go install binaries), Hosted cargo vex attests not_affected while Cargo.lock also builds an unpatched crates.io copy of the same crate@version #679 (cargo dual source), Hosted Composer vex attests not_affected for an unpatched package when config.vendor-dir is absolute or uses ~/ or $HOME/ #686 (Composer absolute vendor-dir), Yarn classic VEX attests not_affected while a bundled copy of the patched package@version stays unpatched (yarn.lock has no inBundle, so the #325 fix can't see it) #758 / Warn during pnpm scans when non-registry copies cannot be patched #935 / Hosted yarn classic scan --vex attests not_affected when an npm: alias copy of the patched package was skipped, while standalone vex refuses the same lock #1081 (bundled, file: and alias copies). PR Stop VEX attesting over yarn PnP, pnpm bundled and deno.lock copies #1033 addresses several of these.
• Scale: about 46 open issues mention a VEX or not_affected false attestation, or a crawler blind spot that feeds one, as of 2026-10-08 (a title scan of open issues).
• The installed side is per ecosystem in vex_consumed.rs, which is a third copy of layout knowledge (E40, Tracking: move vex_consumed's per-ecosystem consumed-copy rules from the CLI into core #855). Option B makes that module the single gate, so its gaps would turn into missing attestations (fail-closed) instead of false ones.

Consequences

• A: no user-visible change. The false-attestation class stays open-ended, with one bug per package-manager quirk, and E72 / PR Stop VEX attesting over yarn PnP, pnpm bundled and deno.lock copies #1033 keep growing.
• B:
  • Lock-only CI checkouts stop attesting unless they pass the flag.
  • docs/usage.md ("Before installation, hosted VEX can describe the pinned dependency state") and the CLI_CONTRACT VEX section change, along with the vex e2e suites that assert attestation from the lockfile basis (for example the pinless_hosted_entry_cannot_use_the_lockfile_basis family, which keeps its meaning under the flag).
  • Removal is roughly the lockfile_attested block plus a flag. The integrity_required plumbing stays, because it gates the flag.
• C: an additive contract change to the statement text. Consumers keyed on the exact impact string need a note in the provenance-marker contract.

Dependencies

• Blocks: E72's remaining items, including Maven integrity_required = false.
• Unaffected: the in-run scan --vex exemption, and vendored evidence (artifacts are hashed).
• Independent of Decide: warn on and then remove scan --apply/--vendor, and whether --vex stays embedded #966 Q2 (whether --vex stays embedded).