flaglint @flaglintdev

LaunchDarkly stays as your provider. OpenFeature becomes the application-facing API. No rip-and-replace. No vendor migration project. Just a clean abstraction boundary npx flaglint scan ./src — free, local, nothing changes until you say so. github.com/flaglint/flagl…

flaglint validate --no-direct-launchdarkly CI gate. Exits 1 if any direct LD evaluation call appears outside your bootstrap file. Stops migration rot. New engineers can't accidentally re-introduce direct ldClient calls without CI catching it.

flaglint migrate --dry-run Generates before/after diffs — but only for call sites where the flag key, fallback, type, context, and OpenFeature client binding are all statically provable. Dynamic keys, detail methods, bulk calls: reported for manual review.

So I built FlagLint. AST-based scanner for direct LaunchDarkly Node.js SDK calls. flaglint scan ./src Finds every ldClient call, by file and line. JSON / Markdown / HTML / SARIF output.

Dynamic keys make it worse. const flag = `feature-${name}` await ldClient.boolVariation(flag, ctx, false) You can't safely automate this. The key isn't known until runtime. A codemod that rewrites it anyway is lying to you.

LaunchDarkly: ldClient.boolVariation(key, context, fallback) OpenFeature: openFeatureClient.getBooleanValue(key, fallback, context) Argument order is swapped. A grep-and-replace migration silently puts the wrong value in production for fallback users. Nobody catches.

The LaunchDarkly → OpenFeature migration looks simple. It isn't. Here's the thing that nearly broke prod 🧵

FlagLint is open source and available now: npx flaglint scan . I’m especially looking for feedback from Node.js teams using LaunchDarkly wrappers, shared clients, or complex evaluation patterns. What would it need to support before you tried it in a real repo?

I just published Standardizing Feature Flags Is Easy to Agree On. Migrating Safely Is the Hard Part. medium.com/p/standardizin…

FlagLint — an open-source CLI for Node.js teams migrating direct LaunchDarkly SDK usage to OpenFeature safely. ✓ Scan direct usage ✓ Preview safe rewrites ✓ Enforce the boundary in CI with SARIF Try v0.5.1: npx flaglint scan . flaglint.dev Feedback welcome.