Carry scan's lockfile-only and vendored-ledger candidates without a fabricated node_modules path #1113

[agent] Filed by the scheduled architecture audit routine (ecosystems and formats). Register: discussion #560 register.

Kind: refactor. Source: Part 6.2 ("fabricated CrawledPackages"); register E36, child 1 of #1112.

Problem

scan turns lock-inventory entries and vendor-ledger entries into fake installed packages:

• scan/discovery.rs#L111-L133 crawled_from_purl sets path: cwd.join("node_modules").join(name_part) for every ecosystem. A lockfile-only pkg:cargo/serde@1.0.0 or pkg:pypi/six@1.16.0 gets <cwd>/node_modules/serde or <cwd>/node_modules/six.
• It is called by lockfile_supplement (#L88) and vendored_ledger_supplement (#L215).``

Because the paths are fake, the caller keeps parallel sets that say which entries to distrust:

• supplement_purls (scan/mod.rs#L1807-L1835),`` which exists only so the PATH-scope filter (#L1926-L1962) can skip them;
• lockfile_only.purls, consulted through lockfile_only_contains at scan/mod.rs 801, 2821 and 3121 and at discovery.rs 299.

Every new consumer of all_crawled that reads .path (for example gradle_cache::installed_copies(&pkg.path, …) in preverify_vendor_baselines, or is_gradle_version_dir(&p.path) at scan/mod.rs 1206) has to remember that some paths are placeholders. Today these happen to degrade safely, because Maven and Gradle never reach the inventory.

Proposed change

• Add a scan-local candidate type, for example:

  enum Candidate { Installed(CrawledPackage), LockOnly { purl, eco }, Vendored { purl, eco } }

  Alternatively, keep CrawledPackage for crawler output only and carry the supplement as purl-only records beside it.
• The PATH-scope filter matches Installed only. "Not installed" is matches!(c, Candidate::LockOnly { .. }).
• Delete: crawled_from_purl, supplement_purls and the LockfileSupplement::packages / LedgerSupplement::packages vectors of fabricated packages.
• Keep lockfile_only.purls only where API-spelled purls are matched (lockfile_only_contains bridges the percent-encoding and composer padding). Where the candidate itself is at hand, derive the answer from the candidate.
• No behavior change: same JSON (lockfileOnlyPackages, notInstalled, the [NOT INSTALLED] marker, path_scope_excluded_supplements), same exit codes.

Size and scope

• crates/socket-patch-cli/src/commands/scan/{mod.rs,discovery.rs}, plus any scan helper typed on &[CrawledPackage] that receives supplements. Estimate about 150–300 changed production lines.
• Out of scope: the core inventory model (later children of the tracking issue), apply.rs's own lockfile_resolved set, and crawler changes.

Acceptance criteria

• crawled_from_purl and supplement_purls are deleted, and no CrawledPackage is constructed in commands/scan/ outside tests.
• The existing scan/discovery.rs unit tests (ledger_supplement_*, corrupt_ledger_*) are ported and green.
• The CLI scan e2e suites stay green, including scan_paths_e2e (path scope and the path_scope_excluded_supplements warning), the lockfile-only/notInstalled tests, and the vendored-ledger fresh-clone tests.
• A regression test: a path-scoped scan over a project with a lockfile-only cargo or pypi package excludes it with the counted warning, and never treats <cwd>/node_modules/<name> as its location, even when such a directory exists.

Dependencies

• Decide vendored-entry liveness through one discovery verdict #1050 edits vendored_ledger_supplement (liveness verdict). Rebase after it lands.
• Fix 15 open pnpm issues across hosted, vendored and agent modes #1007, Fix open npm issues #1008, Route JVM layout through one module and fix three JVM scope bugs #1032 and Decide whether a hosted patch is pinned through lockfile discovery alone #1058 touch scan/mod.rs elsewhere; expect small rebases.
• Blocks the later checklist items of Tracking: derive scan candidates, lock entries and hosted refs from one project inventory instead of four discovery systems #1112, which replace the candidate's source with core Instances.

Backlog review — 2026-10-08

Consolidated into #1112. The retained tracker(s) preserve this issue’s implementation scope and acceptance criteria. Closing this separate scheduling item as not planned, not as completed.

Explicit candidate-type child of the unified inventory tracker; one parent issue is enough to schedule it.