@sentry/cloudflare/vite: Auto-instrumentation skips the Worker when wrangler `main` is a package specifier

Description

sentryCloudflareVitePlugin() does not wrap the Worker when main in the Wrangler config is a package specifier and not a file path. The build succeeds, but the bundle contains no Sentry code, and the plugin logs no warning.

@cloudflare/vite-plugin supports this config, and vinext generates it by default with vinext init --platform=cloudflare:

// wrangler.jsonc
{
  "main": "vinext/server/fetch-handler",
  // ...
}

// vite.config.ts
export default defineConfig({
  plugins: [
    vinext(),
    cloudflare({ viteEnvironment: { name: "rsc", childEnvironments: ["ssr"] } }),
    sentryCloudflareVitePlugin(),
  ],
});

Tested with @sentry/[email protected], @cloudflare/[email protected], [email protected], [email protected] and Vite 8.3.

Cause

resolveWranglerConfig() calls unstable_readConfig() without preserveOriginalMain (wranglerConfig.ts#L70). Wrangler then resolves every main as a path relative to the config file:

main: "vinext/server/fetch-handler"
-> <project>/vinext/server/fetch-handler   (file does not exist)

autoInstrument.ts compares this path with the module IDs in transform (L75), so no module matches. resolveInstrumentFile() also looks for instrument.server.* in the directory of this path (instrumentFile.ts#L23), and a package entry has no such file.

@cloudflare/vite-plugin handles the same value differently:

1. It reads the config with unstable_readConfig(..., { preserveOriginalMain: true }).
2. maybeResolveMain() makes main absolute only when it ends with a JS or TS extension.
3. It resolves the entry with Vite: await this.resolve(workerConfig.main).

Workaround

Add a local entry that re-exports the package entry, and set main to it. Put instrument.server.ts in the same directory:

// worker/index.ts
import handler from "vinext/server/fetch-handler";

export default handler;

{ "main": "./worker/index.ts" }

Proposed fix

• Read the config with preserveOriginalMain: true, and keep a package specifier unchanged.
• Resolve main with this.resolve() (for example in buildStart, or lazily in transform), and compare the resolved module ID.
• When the resolved entry is in node_modules, look for instrument.server.* in the Wrangler config directory (the Vite root) and not next to the entry.
• Log a warning when main does not resolve to a module that the plugin transforms, so the failure is not silent.
• Add a test fixture where main is a package specifier.