Formal models and scripts: upstream-delta-columnar-dense-vector-batch

Tools: Python

These are the working models and scripts this part of the hunt used. Some encode the code as it is (a counterexample is the expected result), others a fixed or correct variant; read the header comment of each file. Paths inside them were replaced by placeholders such as $LUCENE (a Lucene checkout) and $WORK.

Findings

• When IndexWriter#addBatch rejects a vector part-way through a DENSE vector column, the core HNSW and scalar-quantized vectors writers fall out of step with a flat field writer that keeps the default addDenseValues (new in #16734): the next commit closes the IndexWriter, or with assertions off commits a corrupt HNSW graph or misaligned COSINE quantization state (finding LFV-579; repro · finding page)

Files

• dense-vector-wrappers-assume-atomic-delegate/model/dense_vector_commit.py (used for LFV-579)

How to run

• Python: python3 <file>.py; scripts that import z3 need the z3-solver package.

Snapshot of 2026-11-03. AI-assisted; not yet triaged by a human Lucene committer. Feedback: open an issue in lucene-ai-bug-hunt.