[mdjastrzebski]

Summary

Adds TinyFlashList, a minimal version of FlashList v2 (refs/flash-list). It keeps FlashList's core mechanisms and puts each one in a small file a reader can follow:

Mechanism	File	FlashList counterpart
A layout (offset, size) for every item. Unmeasured items use the average measured size. Binary search finds the items in an offset range	layout-manager.ts	LayoutManager.ts, LinearLayoutManager.ts, findVisibleIndex.ts
Engaged range: the viewport plus drawDistance (250 px) on each side	engaged-indices.ts	EngagedIndicesTracker.ts
Recycling: React keys are recycle keys. A key moves from an item that scrolled out to one that scrolled in, but only between items of the same getItemType	render-stack.ts, ViewHolder.tsx	RenderStackManager.ts, ViewHolder.tsx
Measure before paint: a layout effect measures every cell with synchronous measureLayout (Fabric) and re-renders until nothing moves (max 10 passes)	TinyFlashList.tsx, measure-layout.ts	effects in RecyclerView.tsx, measureLayout.ts
Absolutely positioned cells inside one view as tall as the content	ViewHolder.tsx	ViewHolder.tsx
Mutable state objects; React state only triggers re-renders	TinyFlashList.tsx	RecyclerViewManager.ts

src/TinyFlashList/README.md explains the algorithm in plain language and itemizes what is and is not implemented from FlashList. The main omissions are velocity projection and the direction-skewed buffer, progressive first render, bounded relayout, keyExtractor and scroll anchoring, the recycle-pool limit, and the rest of the API.

Other changes

• measure-layout.web.ts: react-native-web's measureLayout is async, so on web DOM sizes are read directly (FlashList does the same).
• The example app gets a TinyFlashList tab. Every 20th row is a section header, which gives getItemType two types to work with.
• README usage section.

Known limitations

• New architecture only, like FlashList v2.
• renderItem must be stable, because ViewHolder is memoized.
• Row state survives recycling. There is no useRecyclingState.
• Inserting items above the viewport makes the content jump. Keys and layouts follow the index.

Testing

• yarn typecheck, yarn lint and yarn test (59 tests) pass on the rebased branch.
• There are unit tests for the layout manager, engaged range and render stack. The component tests mock measurement, as FlashList's tests do. One of them checks recycling: after a scroll from the top to item 35, 35 different items have been shown but only 20 cells were ever mounted.
• Smoke-tested the web export of the example in headless Chromium. At scroll offsets 0, 3,000, 20,000 and 150,000 px, 15–19 cells were mounted, with no gaps, no overlaps and no console errors.
• Not run on an iOS or Android device yet.

🤖 Generated with Claude Code

https://claude.ai/code/session_014zUjsSmEnFHTMD6LrCrjyQ