[quality] owners.ts truncated-tree probes (probeOwners, probeBranchOwners arms) are never driven through dist/index.js #319

Finding

src/utils/owners.ts has two fallbacks for a recursive tree listing that GitHub truncates, plus the failure arms around them, that only the unit suite reaches. The bundle e2e suite (__tests__/bundle, the only place the shipped dist/index.js is exercised) never drives them:

• probeOwners (L243–268): when git/trees/basesha (the base branch tip) answers truncated: true, loadOwnersTree reads each candidate OWNERS path directly via repos.getContent (404 → skip, other error → error loading OWNERS files at basesha). No bundle test serves a truncated base tree.
• probeBranchOwners (L325, L331–344): the tide gate's probe of the pull request's base branch. Bundle tests only ever serve a 404 tree (62 of 69 calls) or a complete tree that carries an OWNERS blob (7). Unreached: a complete tree without an OWNERS blob (→ gate wants lgtm alone), a truncated tree without one (→ root contents/OWNERS?ref=master probe: 200 → true, 404 → false, other → error probing for a root OWNERS file at master), and a tree listing that fails other than 404 (→ error listing the tree of master).
• repoHasOwners / defaultBranch (L282–285, L348–360): reached only from a pull_request / pull_request_review payload with no pull_request.base.ref, which GitHub always sends. Defensive arm; noted, not part of the deliverable.

Evidence

• Unit: npx vitest run --coverage on main @ 3fc21f2 (Node v26.10.0, vitest 5.0.3, @vitest/coverage-v8) — repo-wide 100 % stmts / 99.81 % branches / 100 % funcs / 100 % lines; owners.ts 100 % lines.
• End-to-end: npm run test:coverage:e2e on main @ 3fc21f2 (5 bundle files / 142 tests) — owners.ts 66.96 % lines (75/112), 68.66 % branches (92/134); uncovered lines 46, 164, 197, 202–203, 229, 244–267, 283–284, 298, 302–303, 325, 331–344, 349–358. Function hits: probeOwners 0, repoHasOwners 0, defaultBranch 0, probeBranchOwners 69 (all via the 404 or OWNERS-blob arms).
• The unit and e2e coverage maps cannot be line-merged ([quality] the bundle e2e suite's coverage of src/ is never captured — runBundle.ts drops NODE_V8_COVERAGE and dist/ has no source map #235 / test(coverage): add test:coverage:e2e to report the bundle suite's coverage of src/ #274), so the two sources are stated separately. Priority follows the unit-covered / not-e2e-covered rule: medium.

Recommendation

• Add __tests__/bundle/ownersProbeArms.test.ts driving /approve by an approver on a pull request through dist/index.js against fakeGithub with: a truncated base tree (root OWNERS 200 + sdk/OWNERS 404 → approves without a blob read; a 500 probe → /approve fails, no write); and for the tide gate's base-branch probe, a complete tree without OWNERS (merges on lgtm alone), a truncated tree with and without a root OWNERS file, a 500 root probe, and a 500 tree listing.

Disjoint from the held bundle PRs: #283 (ownersAuth.test.ts, auth.ts OWNERS arms, complete trees only), #298 (ownersLabelArms.test.ts), #289 (mergeGateLabels.test.ts, labelMatch.ts patterns), #286 (approveReview.test.ts).

Priority

• Impact: medium — the truncated-tree fallbacks are what keeps /approve and the tide gate correct on large repositories, and nothing exercises them end-to-end
• Effort: low

Filed by quality agent (hold-gated mode)

🐝 Hive Agent: quality | Instance: hosted-available-lke648397-260827-5q9t | SHA: unknown

— hive: agent=quality backend=copilot model=claude-fable-5.1 copilot=1.0.88