fix(review): scan patch-less PR files for leaked secrets (#audit-3.4)

[RealDiligent]

Summary

Closes the patch-less bypass gap in the unconditional secret_leak hard blocker (#audit-3.4). GitHub omits inline patch for binary/large PR files; without Contents API fallback, credentials in those files evaded the gate.

Supersedes closed #2821, #3464, #3473, #3481, #3484.

Fix

• src/queue/patchless-secret-scan.ts — Contents API fallback synthesizing scannable + lines; +1 fetch probe so oversized files fail closed (not truncated-prefix scan)
• Wire into maybeAddSecretLeakFinding with installationId, headSha, baseSha
• Precheck — skip makeGithubFileFetcher when every changed file already has inline patch (fix(review): scan patch-less PR files for leaked secrets #3484 review nit)
• Detail cap — incomplete-path advisory lists first 5 paths + remainder count

Linked issue / authorization

No dedicated upstream tracking issue existed before contributor attempts #2821–#3484 (the last passed CI + codecov but was auto-closed for missing a pre-existing issue link). This PR implements the security fix those PRs described — completing an outstanding hole in the #audit-3.4 unconditional blocker (shipped in #1237; parent self-host review-gap audit #1936).

Test plan

• npm run typecheck
• test/unit/patchless-secret-scan.test.ts — 44 tests, 100% line coverage on patchless-secret-scan.ts locally

[superagent-security]

Superagent didn't find any vulnerabilities or security issues in this PR.

[loopover-orb]

Warning

🟨🟨🟨🟨🟨🟨🟨🟨🟨🟨🟨🟨

⏸️ Gittensory review result - manual review recommended

_{Review updated: 2026-07-05 11:15:09 UTC}

3 files · 1 AI reviewer · no blockers · readiness 80/100 · CI green · clean

⏸️ Suggested Action - Manual Review

Review summary
The change adds a bounded Contents API fallback for patch-less PR files and wires it into the deterministic secret-leak scan before building the scan corpus. The main security path is covered: patch-less added files are scanned from head content, modified/renamed files diff against base content, and unreadable or oversized eligible files fail closed with an advisory finding. I do not see a reachable correctness break in the provided diff; the notable residual risk is around defensive handling of unusual PR file statuses or missing head/base metadata rather than the implemented hot path.

Nits — 5 non-blocking

• nit: test/unit/patchless-secret-scan.test.ts:1 starts with a UTF-8 BOM before the import; remove it so the new test file matches the repo's normal ASCII/UTF-8-without-BOM style.
• nit: src/queue/patchless-secret-scan.ts:49 treats any non-added/non-modified/non-renamed status as ineligible, so confirm this repository never receives GitHub's less-common PR file statuses as modified-equivalent before relying on the fallback for every patch-less text change.
• nit: src/queue/processors.ts:6768 logs only the repository and pull number when fallback setup fails; adding the count of eligible patch-less files would make fail-closed incidents easier to triage without exposing file content.
• src/queue/patchless-secret-scan.ts:47: add an explicit test or comment for the PR file statuses emitted by listPullRequestFiles so future status-normalization changes do not silently skip patch-less candidates.
• test/unit/patchless-secret-scan.test.ts:1: remove the BOM from the new test file.

Signal	Result	Evidence
Code review	✅ No blockers	1 reviewer
Linked issue	✅ Linked	#2821
Related work	✅ No active overlap found	No same-issue or scoped active PR overlap found.
Change scope	✅ 20/20	Low review scope from cached public metadata (1 linked issue).
Validation posture	❌ 5/25	Preflight is holding this PR: the review lane is unavailable, so it is not ready for automated review.
Contributor workload	✅ 10/10	Author activity: 146 registered-repo PR(s), 19 merged, 0 issue(s).
Contributor context	✅ Confirmed Gittensor contributor	RealDiligent; Gittensor profile; 146 PR(s), 0 issue(s).
Gate result	✅ Passing	No configured blocker found.

Review context

• Author: RealDiligent
• Role context: outside_contributor
• Public audience mode: oss maintainer
• Lane context: Repository registration is not available in the local Gittensory cache.
• Public profile languages: JavaScript, Ruby, Svelte, TypeScript, Cuda, Markdown
• Official Gittensor activity: 146 PR(s), 0 issue(s).
• PR-specific overlap: none found.

Contributor next steps

• Await review-lane availability.
• Refresh registry data or choose a registered active repo.

Signal definitions

• Related work = same linked issue, overlapping active PRs, or title/path similarity.
• Change scope = cached public metadata such as size labels, draft state, and review-burden hints.
• Validation posture = whether the PR provides enough public validation/test evidence for maintainer review.
• Contributor workload = public contributor activity and cleanup pressure, not a repo-wide quality failure.
• Contributor context = public GitHub/Gittensor identity context; non-Gittensor status is not a blocker.

_{🟩 Safe / merged · 🟦 Advisory · 🟨 Held for review · 🟥 Blocked / closed}

---

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 93.06%. Comparing base (6452202) to head (788bd89).

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #3493      +/-   ##
==========================================
+ Coverage   93.04%   93.06%   +0.01%     
==========================================
  Files         299      300       +1     
  Lines       31211    31298      +87     
  Branches    11389    11421      +32     
==========================================
+ Hits        29039    29126      +87     
  Misses       1517     1517              
  Partials      655      655              

Files with missing lines	Coverage Δ
src/queue/patchless-secret-scan.ts	100.00% <100.00%> (ø)
src/queue/processors.ts	93.48% <100.00%> (+0.02%)	⬆️

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[loopover-orb]

Gittensory approves — the gate is satisfied and CI is green.