LLMQ: Handle empty contribution batches

[navidR]

Handle contribution batches that become empty after filtering, and complete empty BLS verification requests immediately. This prevents DKG phase processing from waiting indefinitely and adds focused regression coverage.

Upstream: Dash PR #7486.

[codeant-ai]

🤖 CodeAnt AI — Review Status

Status	Commit	Started (UTC)	Finished (UTC)
✅ Reviewed your PR	fcf775b	Aug 30, 2026 · 14:55	14:58

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Codex Review Summary

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Review	Status	Commit	Review trigger
📝 Code Review	✅ Completed 2026-08-30T14:56:29.946590Z	fcf775b	PR opened

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User description

Handle contribution batches that become empty after filtering, and complete empty BLS verification requests immediately. This prevents DKG phase processing from waiting indefinitely and adds focused regression coverage.

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CodeAnt-AI Description

Prevent empty DKG contribution batches from getting stuck

What Changed

• Empty contribution verification requests now finish immediately with no results
• DKG processing skips verification when all pending contributors have become invalid
• Added regression coverage for empty verification batches in both supported verification modes

Impact

✅ DKG sessions no longer wait indefinitely on empty contribution batches
✅ Empty BLS verification requests complete immediately
✅ Reliable handling of contributors invalidated after queuing

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No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: Repository UI

Review profile: CHILL

Plan: Pro Plus

Run ID: 7c6ff771-2aa5-4f50-9202-2ef2b2dbfe1d

📥 Commits

Reviewing files that changed from the base of the PR and between 4f0c771 and fcf775b.

📒 Files selected for processing (3)

• src/bls/bls_worker.cpp
• src/llmq/quorums_dkgsession.cpp
• src/test/bls_tests.cpp

Included review availability: Your plan provides up to 4 included reviews per hour; 3 remain after this review.

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Summary by CodeRabbit

• Bug Fixes

  • Improved handling of empty contribution-share verification requests.
  • Prevented unnecessary verification attempts when all pending contributions are skipped.
  • Improved stability during quorum contribution processing.

• Tests

  • Added coverage for empty contribution-share verification in both supported modes.

Walkthrough

The change adds early returns for empty contribution verification inputs in the BLS worker and DKGS session. A BLS test verifies that empty aggregated and non-aggregated inputs invoke the callback with an empty result.

Changes

Empty contribution verification handling

Layer / File(s)	Summary
Worker empty-input guard and validation src/bls/bls_worker.cpp, src/test/bls_tests.cpp	AsyncVerifyContributionShares now invokes the callback immediately with an empty result when vvecs is empty. Tests cover aggregated and non-aggregated calls.
DKG empty-member guard src/llmq/quorums_dkgsession.cpp	VerifyPendingContributions now returns when no member indexes remain after pending members are excluded.

Estimated code review effort: 2 (Simple) | ~10 minutes

Merge Risk: ⚪ Minimal · up to fcf77

Empty contribution batches now complete without stalling DKG processing, while non-empty verification behavior remains unchanged. No actionable merge-blocking risk remains after normal checks and review.

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 25.00% which is insufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 4 functions across 3 files.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Description check	✅ Passed	The description explains the intended fix, its effect on DKG processing, and the added regression coverage. It does not use the template headings, but it provides the required intention and code-chang…
Title check	✅ Passed	The title clearly identifies the main change: handling empty contribution batches in LLMQ processing.

Full details: Description check

Explanation

The description explains the intended fix, its effect on DKG processing, and the added regression coverage. It does not use the template headings, but it provides the required intention and code-change information.

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CodeAnt Nitpicks

1 code suggestion

1. When vvecs is empty but skShares is not, this returns an empty result and silently accepts mismatched input instead of rejecting it.

Api mismatch · src/bls/bls_worker.cpp:729-732

[reubenyap]

I reviewed both synchronous and asynchronous empty-input behavior and traced the DKG path where every queued contributor becomes invalid before verification. The member-index, verification-vector, and secret-share collections are built in lockstep; the new guard safely drains the moved queue and avoids constructing the verifier with zero inputs. The focused tests and full CI matrix are green; I found no actionable defect.