fix(miner): log discovery-index query failures before failing open

[jeffrey701]

What

queryDiscoveryIndex in packages/loopover-miner/lib/discovery-index-client.ts had a bare
} catch { return EMPTY_QUERY_RESPONSE; } — any fetch/network/parse failure was silently dropped
with zero logging, even at --verbose.

Its sibling submitSoftClaim in the same file — the equivalent best-effort fire-and-forget network
call — already logs the failure before returning its fail-open result:

} catch (error) {
  getLogger().debug("discovery_plane_soft_claim_failed", { error: describeCliError(error) });
  return { sent: false };
}

Change

Give queryDiscoveryIndex's catch the same treatment: bind the error (catch (error)) and
getLogger().debug("discovery_plane_query_failed", { error: describeCliError(error) }) before
returning. The fail-open behavior and the EMPTY_QUERY_RESPONSE return type are unchanged — this only
adds visibility. submitSoftClaim is untouched (it is the precedent). The event name mirrors its
discovery_plane_soft_claim_failed convention.

Validation

• New test in test/unit/miner-discovery-index-client.test.ts: when the injected fetchImpl throws,
  queryDiscoveryIndex still returns empty (candidates: []) and logSpy.debug is called with
  "discovery_plane_query_failed" and { error: "network exploded" } (describeCliError returns the
  Error's message).
• npx vitest run test/unit/miner-discovery-index-client.test.ts → 25 pass. The added lines are
  unconditional (no new branch) and are executed by the throw-path test.

Closes #9329

[superagent-security]

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

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 75.40%. Comparing base (aad3f93) to head (70ade69).
⚠️ Report is 2 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #9346      +/-   ##
==========================================
+ Coverage   75.38%   75.40%   +0.02%     
==========================================
  Files         275      276       +1     
  Lines       58023    58071      +48     
  Branches     6181     6204      +23     
==========================================
+ Hits        43739    43787      +48     
  Misses      14014    14014              
  Partials      270      270              

Flag	Coverage Δ
backend	100.00% <100.00%> (?)

Flags with carried forward coverage won't be shown. Click here to find out more.

Files with missing lines	Coverage Δ
...kages/loopover-miner/lib/discovery-index-client.ts	100.00% <100.00%> (ø)

[loopover-orb]

Tip

✅ LoopOver review result - approve/merge recommended

_{Review updated: 2026-07-27 13:42:45 UTC}

2 files · 1 AI reviewer · no blockers · readiness 98/100 · CI green · clean

✅ Suggested Action - Approve/Merge

• safe to merge

Review summary
This is a minimal, well-scoped fix mirroring submitSoftClaim's existing error-logging pattern exactly: it binds the caught error and logs it via getLogger().debug with the same describeCliError shape before returning EMPTY_QUERY_RESPONSE. The fail-open behavior and return type are unchanged, only visibility is added, and the new test exercises the real throw-path (fetchImpl throws) rather than a fabricated scenario, verifying both the empty return and the logSpy call. Closes the linked issue #9329 and is narrowly targeted with no scope creep.

Nits — 2 non-blocking

• The inline comment at discovery-index-client.ts:110-111 restates what the code/PR description already says (matching submitSoftClaim's convention) rather than explaining a non-obvious constraint — could be trimmed to a single short line.
• Consider asserting `logSpy.debug` was called exactly once in the new test to guard against future double-logging regressions in this catch block.

Decision drivers

• ✅ Code review — No blockers (1 reviewer)
• ✅ Gate result — Passing (No configured blocker found.)

Context & advisory signals — never blocks the verdict

Signal	Result	Evidence
Linked issue	✅ Linked	#9329
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	✅ 25/25	PR body includes validation/test evidence.
Contributor workload	✅ 10/10	Author activity: 83 registered-repo PR(s), 38 merged, 17 issue(s).
Contributor context	✅ Confirmed Gittensor contributor	jeffrey701; Gittensor profile; 83 PR(s), 17 issue(s).
Improvement	✅ Minor	risk: clean · value: minor · LLM: minor

Linked issue satisfaction

Addressed
The catch block now binds the error and logs it via getLogger().debug("discovery_plane_query_failed", { error: describeCliError(error) }) before returning EMPTY_QUERY_RESPONSE, exactly mirroring submitSoftClaim's pattern, and a new test verifies both the fail-open return value and the logger call on the throw path.

Review context

• Author: jeffrey701
• Role context: outside_contributor
• Public audience mode: oss maintainer
• Lane context: Repository is configured for direct PR review.
• Public profile languages: Rust, TypeScript, Clojure, JavaScript
• Official Gittensor activity: 83 PR(s), 17 issue(s).
• PR-specific overlap: none found.

Contributor next steps

• Keep the PR focused and include validation evidence before maintainer review.

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.

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

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[loopover-orb]

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