Fixture/snapshot tests for split, merge, overlap, and the analyzer

[willscott-v2]

Stacked on #12 (v3.4). Merge order: #10 → #11 → #12 → #13, retargeting each to main as its base lands.

Why

Deferred since v3.1 — and now overdue: the Chunkability score makes chunking behavior load-bearing, so an accidental change to splitting, merging, overlap, or extraction silently changes client-facing scores. Now it fails a test instead. 30 tests, ~0.6s, node:test only — zero new dependencies. Run with npm test.

What's covered

Unit — chunking primitives (tests/chunking.test.js): recursiveSplit (respects limits, preserves every word in order, prefers paragraph boundaries, force-splits giant sentences), mergeSmallChunks, addOverlap (prefix equals the previous chunk's tail, overlap_word_count recorded, the exact 29-word clamp case from the page Chuck screenshotted, no-op paths), initialism, and Flesch-Kincaid determinism/ordering.

Unit — analyzer (tests/analyzer.test.js): one isolated scenario per flag — dangling-reference, thin, oversized, generic-heading (and its answer-buried skip), answer-buried (and the single-word-heading skip), no-entity-anchor (and UWM-style initialism anchoring), near-duplicate (flags both chunks, counted once as a pair), overlap-prefix exclusion from duplicate/thin checks, readability info flags — plus the per-chunk-average score math (85/B case with exact top_fixes), full determinism, and empty input → null.

Fixture snapshots (tests/fixture-snapshot.test.js): two committed HTML fixtures run through the full offline pipeline (extractSourceMetadata → buildChunks → enhanceChunks → analyzeChunks), with the entire result deep-equaled against committed *.snapshot.json. Intentional behavior changes regenerate with UPDATE_SNAPSHOTS=1 npm test, so the diff shows up in review. nested-sections.html is the dedicated regression fixture for the v3.3 parent-swallows-child extraction fix, with explicit asserts on top of the snapshot. Snapshots use the estimate tokenizer so they don't churn with gpt-tokenizer releases.

Plumbing

• api/chunk.js gains a named-export block for the test surface — runtime unchanged (Vercel only uses the default handler; verified the running API afterward)
• .github/workflows/test.yml runs npm ci && npm test on PRs and pushes to main (Node 22)
• npm test uses a quoted glob because the directory form of node --test fails silently on Node 22.22

🤖 Generated with Claude Code

[vercel]

The latest updates on your projects. Learn more about Vercel for GitHub.

Project	Deployment	Actions	Updated (UTC)
getchunks	Ready	Preview, Comment	Jul 25, 2026 9:17pm