label_communities ran batches one LLM call at a time, so a large graph needed
hundreds of sequential calls even on backends that allow heavy concurrency. It
now fans batches out across a thread pool, mirroring extract_corpus_parallel:
results are returned per batch and merged on the main thread (labels dict is
never mutated concurrently, no lock), and workers==1 keeps the original
sequential path verbatim. ollama and claude-cli are forced serial unless the
matching GRAPHIFY_*_PARALLEL env opt-in is set (same guard as extract).
generate_community_labels threads max_concurrency + batch_size through, and the
cluster-only/label CLI parses --max-concurrency and --batch-size (both `--flag N`
and `--flag=N` forms; the space form is parsed explicitly so the value is not
mistaken for the positional scan path by the arg-walk's catch-all).
Output is deterministic regardless of concurrency (keyed by community id). Tests:
parallel == sequential result, batch-size controls batch count, batches actually
run concurrently, ollama forced serial, and the CLI parses both new flags. Full
suite 2393 passed; ruff clean.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
