fix: make default usePrebuiltRNCore version-aware

Author: artus9033

packages/cli/src/brownfield/commands/packageIos.ts

@@ -81,18 +81,30 @@ export const packageIosCommand = curryOptions(
     actionRunner(async (options: PackageIosCliFlags) => {
       const { projectRoot, platformConfig, userConfig } = getProjectInfo('ios');
 
-      const {
-        supported: isPrebuiltRNCoreSupported,
-        reason: maybePrebuiltRNCoreUnsupportedReason,
-      } = supportsPrebuiltRNCore({ projectRoot });
-
-      // default value is based on project so is dynamically assigned at runtime
-      options.usePrebuiltRnCore ??= isPrebuiltRNCoreSupported;
-
-      if (options.usePrebuiltRnCore && !isPrebuiltRNCoreSupported) {
-        // user opted-in but prebuilt RN core is not supported
-        // note: the default-assignment above - if effective - always satisfies this condition
-        throw new RockError(maybePrebuiltRNCoreUnsupportedReason);
+      const prebuiltRNCoreSupport = supportsPrebuiltRNCore({ projectRoot });
+
+      // version-aware default when the flag is omitted (see ios.mdx "React Native Prebuilts")
+      options.usePrebuiltRnCore ??= prebuiltRNCoreSupport.supported
+        ? prebuiltRNCoreSupport.enabledByDefault
+        : false;
+
+      if (prebuiltRNCoreSupport) {
+        logger.info(
+          `${options.usePrebuiltRnCore ? 'Using' : 'Not using'} prebuilt RN core`
+        );
+
+        if (
+          !prebuiltRNCoreSupport.enabledByDefault &&
+          !options.usePrebuiltRnCore
+        ) {
+          logger.info(
+            'Your environment supports prebuilt RN Core as an opt-in feature, but it is disabled by default. Pass --use-prebuilt-rn-core to enable it.'
+          );
+        }
+      }
+
+      if (options.usePrebuiltRnCore && !prebuiltRNCoreSupport.supported) {
+        throw new RockError(prebuiltRNCoreSupport.reason);
       }
 
       await runExpoPrebuildIfNeeded({ projectRoot, platform: 'ios' });

packages/cli/src/brownfield/utils/__tests__/supportsPrebuiltRNCore.test.ts

@@ -28,12 +28,23 @@ describe('supportsPrebuiltRNCore', () => {
     vi.mocked(projectUtils.getExpoSdkMajor).mockReset();
   });
 
-  test('returns supported for vanilla RN >= 0.81', () => {
+  test('returns supported with opt-in default for vanilla RN 0.83', () => {
     vi.mocked(rockTools.getReactNativeVersion).mockReturnValue('0.83.0');
     vi.mocked(projectUtils.isExpoProject).mockReturnValue(false);
 
     expect(supportsPrebuiltRNCore({ projectRoot: '/project' })).toEqual({
       supported: true,
+      enabledByDefault: false,
+    });
+  });
+
+  test('returns supported with default enabled for vanilla RN >= 0.84', () => {
+    vi.mocked(rockTools.getReactNativeVersion).mockReturnValue('0.84.0');
+    vi.mocked(projectUtils.isExpoProject).mockReturnValue(false);
+
+    expect(supportsPrebuiltRNCore({ projectRoot: '/project' })).toEqual({
+      supported: true,
+      enabledByDefault: true,
     });
   });
 
@@ -63,13 +74,14 @@ describe('supportsPrebuiltRNCore', () => {
     });
   });
 
-  test('returns supported for Expo SDK >= 55 when RN is supported', () => {
+  test('returns supported with default enabled for Expo SDK >= 55', () => {
     vi.mocked(rockTools.getReactNativeVersion).mockReturnValue('0.83.0');
     vi.mocked(projectUtils.isExpoProject).mockReturnValue(true);
     vi.mocked(projectUtils.getExpoSdkMajor).mockReturnValue(55);
 
     expect(supportsPrebuiltRNCore({ projectRoot: '/project' })).toEqual({
       supported: true,
+      enabledByDefault: true,
     });
   });
 
@@ -82,7 +94,7 @@ describe('supportsPrebuiltRNCore', () => {
 
     expect(result).toEqual({
       supported: false,
-      reason: expect.stringMatching(/Expo SDK 55 or newer/),
+      reason: expect.stringMatching(/Expo SDK 54.*requires Expo SDK 55 or newer/),
     });
   });
 });

packages/cli/src/brownfield/utils/supportsPrebuiltRNCore.ts

@@ -2,12 +2,16 @@ import { getReactNativeVersion, versionCompare } from '@rock-js/tools';
 
 import { getExpoSdkMajor, isExpoProject } from './project.js';
 
-export const MIN_REACT_NATIVE_VERSION_FOR_USE_PREBUILT_RN_CORE = '0.81.0';
-export const MIN_EXPO_SDK_MAJOR_FOR_USE_PREBUILT_RN_CORE = 55;
+/** Minimum RN version that can opt in to prebuilts via `--use-prebuilt-rn-core`. */
+export const MIN_REACT_NATIVE_VERSION_FOR_OPT_IN_PREBUILT_RN_CORE = '0.81.0';
+/** Minimum RN version where Brownfield enables prebuilts by default (vanilla projects). */
+export const MIN_REACT_NATIVE_VERSION_FOR_PREBUILT_RN_CORE_BY_DEFAULT =
+  '0.84.0';
+export const MIN_EXPO_SDK_MAJOR_FOR_PREBUILT_RN_CORE_BY_DEFAULT = 55;
 
 export type PrebuiltRNCoreSupportResult =
-  | { supported: true; reason?: never }
-  | { supported: false; reason: string };
+  | { supported: true; enabledByDefault: boolean; reason?: never }
+  | { supported: false; enabledByDefault?: never; reason: string };
 
 export function supportsPrebuiltRNCore({
   projectRoot,
@@ -27,12 +31,12 @@ export function supportsPrebuiltRNCore({
   if (
     versionCompare(
       reactNativeVersion,
-      MIN_REACT_NATIVE_VERSION_FOR_USE_PREBUILT_RN_CORE
+      MIN_REACT_NATIVE_VERSION_FOR_OPT_IN_PREBUILT_RN_CORE
     ) < 0
   ) {
     return {
       supported: false,
-      reason: `--use-prebuilt-rn-core requires React Native ${MIN_REACT_NATIVE_VERSION_FOR_USE_PREBUILT_RN_CORE} or newer (found ${reactNativeVersion}).`,
+      reason: `--use-prebuilt-rn-core requires React Native ${MIN_REACT_NATIVE_VERSION_FOR_OPT_IN_PREBUILT_RN_CORE} or newer (found ${reactNativeVersion}).`,
     };
   }
 
@@ -41,15 +45,23 @@ export function supportsPrebuiltRNCore({
 
     if (
       expoSdkMajor === null ||
-      expoSdkMajor < MIN_EXPO_SDK_MAJOR_FOR_USE_PREBUILT_RN_CORE
+      expoSdkMajor < MIN_EXPO_SDK_MAJOR_FOR_PREBUILT_RN_CORE_BY_DEFAULT
     ) {
       const sdkLabel = expoSdkMajor === null ? 'unknown' : String(expoSdkMajor);
       return {
         supported: false,
-        reason: `--use-prebuilt-rn-core requires Expo SDK ${MIN_EXPO_SDK_MAJOR_FOR_USE_PREBUILT_RN_CORE} or newer (found SDK ${sdkLabel}).`,
+        reason: `--use-prebuilt-rn-core is unsupported in Expo SDK ${sdkLabel}: packaging brownfield with prebuilts requires Expo SDK ${MIN_EXPO_SDK_MAJOR_FOR_PREBUILT_RN_CORE_BY_DEFAULT} or newer.`,
       };
     }
+
+    return { supported: true, enabledByDefault: true };
   }
 
-  return { supported: true };
+  const enabledByDefault =
+    versionCompare(
+      reactNativeVersion,
+      MIN_REACT_NATIVE_VERSION_FOR_PREBUILT_RN_CORE_BY_DEFAULT
+    ) >= 0;
+
+  return { supported: true, enabledByDefault };
 }