fix(nitro): Respect user's explicit sourcemap setting instead of forcing true

Previously, `configureSourcemapSettings` unconditionally set
`config.sourcemap = true`, overriding the user's explicit `false`. This
could expose source maps publicly when users intentionally disabled them.

Now follows the same 3-case pattern as other meta-framework SDKs (Nuxt):
1. User disabled (false) → keep their setting, warn about unminified errors
2. User enabled (true) → keep their setting
3. User didn't set (undefined) → enable for Sentry

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: logaretm

packages/nitro/src/sourceMaps.ts

@@ -90,9 +90,16 @@ export function getPluginOptions(options?: SentryNitroOptions): BundlerPluginOpt
   };
 }
 
-/**
- * Configures the Nitro config to enable source map generation.
- */
+/*  Source map configuration rules:
+    1. User explicitly disabled source maps (sourcemap: false)
+      - Keep their setting, emit a warning that errors won't be unminified in Sentry
+      - We will not upload anything
+    2. User enabled source map generation (true)
+      - Keep their setting (don't modify besides uploading)
+    3. User did not set source maps (undefined)
+      - We enable source maps for Sentry
+      - Configure `filesToDeleteAfterUpload` to clean up .map files after upload
+*/
 export function configureSourcemapSettings(config: NitroConfig, moduleOptions?: SentryNitroOptions): void {
   const sourcemapUploadDisabled = moduleOptions?.sourcemaps?.disable === true;
   if (sourcemapUploadDisabled) {
@@ -101,20 +108,26 @@ export function configureSourcemapSettings(config: NitroConfig, moduleOptions?:
 
   if (config.sourcemap === false) {
     debug.warn(
-      '[Sentry] You have explicitly disabled source maps (`sourcemap: false`). Sentry is overriding this to `true` so that errors can be un-minified in Sentry. To disable Sentry source map uploads entirely, use `sourcemaps: { disable: true }` in your Sentry options instead.',
+      '[Sentry] You have explicitly disabled source maps (`sourcemap: false`). Sentry will not upload source maps, and errors will not be unminified. To let Sentry handle source maps, remove the `sourcemap` option from your Nitro config, or use `sourcemaps: { disable: true }` in your Sentry options to silence this warning.',
     );
+    return;
   }
 
-  config.sourcemap = true;
+  if (config.sourcemap === true) {
+    if (moduleOptions?.debug) {
+      debug.log('[Sentry] Source maps are already enabled. Sentry will upload them for error unminification.');
+    }
+  } else {
+    // User did not explicitly set sourcemap — enable it for Sentry
+    config.sourcemap = true;
+    if (moduleOptions?.debug) {
+      debug.log('[Sentry] Enabled source map generation for Sentry. Source map files will be deleted after upload.');
+    }
+  }
 
   // Nitro v3 has a `sourcemapMinify` plugin that destructively deletes `sourcesContent`,
   // `x_google_ignoreList`, and clears `mappings` for any chunk containing `node_modules`.
   // This makes sourcemaps unusable for Sentry.
-  // FIXME: Not sure about this one, it works either way?
   config.experimental = config.experimental || {};
   config.experimental.sourcemapMinify = false;
-
-  if (moduleOptions?.debug) {
-    debug.log('[Sentry] Enabled source map generation and configured build settings for Sentry source map uploads.');
-  }
 }

packages/nitro/test/sourceMaps.test.ts

@@ -142,16 +142,25 @@ describe('configureSourcemapSettings', () => {
     expect(config.sourcemap).toBe(true);
   });
 
-  it('forces sourcemap to true even when user set it to false', () => {
+  it('respects user explicitly disabling sourcemaps and warns', () => {
     const debugSpy = vi.spyOn(debug, 'warn').mockImplementation(() => {});
     const config: NitroConfig = { sourcemap: false };
     configureSourcemapSettings(config);
 
-    expect(config.sourcemap).toBe(true);
-    expect(debugSpy).toHaveBeenCalledWith(expect.stringContaining('overriding this to `true`'));
+    expect(config.sourcemap).toBe(false);
+    expect(debugSpy).toHaveBeenCalledWith(expect.stringContaining('explicitly disabled source maps'));
     debugSpy.mockRestore();
   });
 
+  it('does not modify experimental config when user disabled sourcemaps', () => {
+    vi.spyOn(debug, 'warn').mockImplementation(() => {});
+    const config: NitroConfig = { sourcemap: false };
+    configureSourcemapSettings(config);
+
+    expect(config.experimental).toBeUndefined();
+    vi.restoreAllMocks();
+  });
+
   it('keeps sourcemap true when user already set it', () => {
     const config: NitroConfig = { sourcemap: true };
     configureSourcemapSettings(config);