[Brooooooklyn]

Control flow analysis

Build time (works)

1. User runs void deploy from playground/react-pages/
2. The CLI shells out to vite build, which invokes @cloudflare/vite-plugin
3. The plugin builds two environments: client (browser JS) and ssr (worker bundle)
4. During the SSR build, the virtual renderer module is generated:

   import React from "react";
   import { renderToString } from "react-dom/server";
   import { SharedContext, ErrorsContext, RouterContext } from "@void/react";

5. @void/react is a pre-built npm package whose dist imports { createContext, useContext } from "react"
6. Rolldown bundles everything into a module graph under dist/ssr/ -- index.js + assets/*.js chunks
7. React ends up in a single CJS-wrapped chunk (react-BVLPaBiV.js) shared by all consumers. No dual React.
8. @cloudflare/vite-plugin writes dist/ssr/wrangler.json with compatibility_flags: ["nodejs_als"] and compatibility_date: "2026-03-29"

Deploy packaging (the first bug)

9. The CLI calls readWranglerCompat(root, config) to get compat settings for the deploy manifest
10. It looks for wrangler.json at the project root (playground/react-pages/) -- does not exist
11. It looks for worker.compatibility_flags in void.json -- not set
12. Falls back to hardcoded defaults: compatibility_date: "2026-02-12", compatibilityFlags: undefined
13. The build output's dist/ssr/wrangler.json (which has the correct settings) is never read
14. The CLI packages all worker files from dist/ssr/ into a FormData with the manifest
15. The manifest has compatibilityFlags: undefined

Server-side deploy (the second bug)

16. The platform API (packages/api/src/routes/deploy.ts) receives the FormData
17. It builds WfP upload metadata:

    compatibility_flags: manifest.compatibilityFlags ?? ["nodejs_compat"]

18. Since manifest.compatibilityFlags is undefined, the fallback ["nodejs_compat"] kicks in
19. The worker is uploaded to Workers for Platforms with:
    • compatibility_flags: ["nodejs_compat"] (wrong -- should be ["nodejs_als"])
    • compatibility_date: "2026-02-12" (wrong -- should be "2026-03-29")

Runtime (the crash)

20. A request hits https://void-test-it.void.app/
21. The dispatch worker (packages/dispatch) routes it to the user's WfP worker
22. The worker's index.js entry handles the request via Hono
23. The route handler calls handlePageGet(...) which calls renderPage(pageObj, assetTags)
24. The virtual renderer builds the React element tree:

    element = React.createElement(SharedContext.Provider, { value: shared },
      React.createElement(ErrorsContext.Provider, { value: errors },
        React.createElement(RouterContext.Provider, { value: null },
          React.createElement(Layout, null,
            React.createElement(HomePage, props)))))

25. It calls renderToString(element) -- this enters React's server renderer
26. React's server renderer sets ReactSharedInternals.H = serverDispatcher and begins rendering
27. The Layout component runs, calls useShared() -> useContext(SharedContext)
28. useContext internally does ReactSharedInternals.H.useContext(context)
29. Under nodejs_compat at compat date 2026-02-12 on WfP, ReactSharedInternals.H is null at this point -- the dispatcher set by renderToString is not visible to the useContext call
30. null.useContext -> TypeError: Cannot read properties of null (reading 'useContext')
31. The worker returns 500

Why it works locally

• vite dev: No bundling. @void/react is excluded from dep optimization (optimizeDeps.exclude), so all code shares the same live React module. nodejs_als is used by the Cloudflare plugin's dev server.
• wrangler dev on build output: Reads dist/ssr/wrangler.json directly, which has the correct nodejs_als flag and 2026-03-29 date. The local workerd runtime evaluates modules correctly under these settings.

The fix

The deploy pipeline now reads the build output's wrangler.json as a fallback source for compat settings (priority: void.json > project wrangler.json > build output wrangler.json > hardcoded default). This ensures the deployed worker runs with the same flags the build was designed for.

Also fixes a separate build failure where island CSS imports with relative paths (e.g. import "./global.css" in a layout) were copied verbatim into the virtual islands-client entry module, where they could not resolve. Now rewrites them to absolute paths.

[Brooooooklyn]

• fix: resolve island CSS paths and deploy compat flag mismatch #71 👈 (View in Graphite)
• main

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