Formal models and scripts: packed-ints-monotonic

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

• (Latent) MonotonicBlockPackedWriter writes a block whose values end close to Long.MAX_VALUE with too few bits, so MonotonicBlockPackedReader returns wrong values: min + (long) (avg * i) overflows in flush() (finding LFV-148; repro · finding page)

Files

• monotonic-block-packed-writer-min-overflow/model/monotonic_block_writer.py (used for LFV-148)

How to run

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

Snapshot of 2026-11-04. AI-assisted; not yet triaged by a human Lucene committer. Feedback: open an issue in lucene-ai-bug-hunt.