Formal models and scripts: hnsw-parallel-repair-tla

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

• HNSW merge with graph reuse throws BufferAllocationException when the reused graph has more than 805,306,368 vectors (finding LFV-458; repro · finding page)

Files

• hnsw-merge-ordmap-hashmap-capacity/model/capacity_bound.py (used for LFV-458)

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.