fix(compiler,vxrn): run codegen on React Native's Flow .js specs

[YevheniiKotyrlo]

Summary

On a native dev build (new architecture / bridgeless), React Native logs a LogBox warning on every render + hot reload:

Codegen didn't run for SafeAreaView. This will be an error in the future. Make sure you are using @react-native/babel-preset when building your JavaScript code.

Non-fatal today, but RN has slated it to become a hard error. SafeAreaView is RN core's own deprecated Flow spec (RCTSafeAreaViewNativeComponent.js) — its codegenNativeComponent<Props>(…) call is never replaced with a static view-config at build time, so the runtime codegenNativeComponent executes and warns.

Root cause

Two layers, both about Flow .js never reaching codegen with its type intact:

1. @vxrn/compiler has no Flow parser for .js. transformBabel adds @babel/preset-typescript only for .ts/.tsx and nothing for .js:

presets: [isTS ? ['@babel/preset-typescript', { isTSX, allExtensions: isTSX }] : '', ...(options.presets || [])].filter(Boolean),

RN's own component specs are Flow .js (import type, codegenNativeComponent<T>(…), (expr: Type) casts). @react-native/babel-plugin-codegen declares no manipulateOptions/inherits, so it doesn't enable Flow parsing itself — its visitor needs babel to have already parsed the TypeCastExpression/CallExpression. With no Flow syntax plugin, babel's parser throws on the first line (Unexpected token … import type); transformBabel only silences "Could not find component config", so it logs and returns undefined, and the file falls back to the SWC path (which strips Flow but does not run codegen). The raw codegenNativeComponent("SafeAreaView", …) survives into the bundle → the runtime warning. (safe-area-context's own spec is a .ts file, so preset-typescript parses it and codegen runs — which is why RNCSafeAreaView works but SafeAreaView doesn't.)

2. On the native bundler, Flow is stripped before codegen can run. getNativePlugins runs flowStripPlugin before the compiler. It matches RN files (node_modules/(react-native|@react-native)/**/*.js) and strips Flow via fast-flow-transform, so codegenNativeComponent<Props>(…) becomes codegenNativeComponent(…) (type erased) before the (now Flow-capable) compiler — which already owns codegen — ever sees it. So fixing (1) alone isn't enough on native: the type argument is already gone.

Fix

Two coordinated changes that keep codegen a single responsibility of @vxrn/compiler.

@vxrn/compiler — parse Flow for non-TS files. Append @babel/plugin-transform-flow-strip-types (which inherits @babel/plugin-syntax-flow, so it both parses and strips) to the plugin list for non-TS files, mirroring @react-native/babel-preset (TS → preset-typescript, JS → this plugin). The general fix — any Flow .js through babel now parses, so the codegen plugin the compiler already runs works on RN specs. The TS path is byte-identical (empty slice).

vxrn — run the compiler before flowStripPlugin. getNativePlugins now orders vxrnCompilerPlugin ahead of flowStripPlugin, so RN's Flow .js specs reach the compiler's codegen with their type argument intact; flowStripPlugin then strips any remaining Flow downstream as the guaranteed safety net before rolldown's oxc core parse. Because the safety net now sits after the transform instead of before it, it can't leave un-stripped Flow for oxc to choke on (the failure mode of the naive "skip specs in flowStrip" alternative).

Dependency: @babel/plugin-transform-flow-strip-types was only present transitively — added to @vxrn/compiler's deps.

Test plan

• Part 1, deterministic (driving the real exported getBabelOptions + transformBabel): the RN core Flow .js spec RCTSafeAreaViewNativeComponent.js — before, transformBabel returns undefined (SyntaxError on import type) and codegen does not run; after, codegen runs, replacing codegenNativeComponent('SafeAreaView', …) with NativeComponentRegistry.get('RCTSafeAreaView', () => __INTERNAL_VIEW_CONFIG). A .ts spec is unchanged (no regression); the TS path is byte-identical.
• On device (Android emulator, Hermes, new arch): the served bundle's raw codegenNativeComponent("SafeAreaView") count goes 1 → 0; the Codegen didn't run warning is gone (initial render + hot reload); app renders + hot-reloads; build healthy. The pipeline reorder is behavior-changing, so an on-device re-smoke is worthwhile.
• No committed unit test: @vxrn/compiler has no test harness today and this entry pulls unbuilt workspace deps, so testing it would need new infrastructure plus a build-before-test step CI doesn't run — out of scope here; the behavior is covered on-device.

Notes

• POSIX-safe — extension/content branches + plugin order, no path logic.
• Single codegen owner: rather than run @react-native/babel-plugin-codegen in two places (the compiler and the strip plugin), the compiler owns it and the pipeline order lets it see the Flow type. This drops a second, divergent codegen gate and a silent catch {} that would otherwise have hidden a future codegen regression behind the exact warning this fixes.
• Architecture: transformBabel owns how to parse a file (dialect by extension: TS vs Flow); the pipeline owns when each transform runs. The bug was that the parse layer only knew TypeScript and the strip ran before the transform — this fixes both.