Fix replace-rncore-version to extract tarball via temp dir for EdenFS compatibility

Extract the rncore tarball to a temporary directory on a regular filesystem
first, then move it to the final location. This avoids issues with partial
tar extraction on EdenFS where extracting directly can silently produce
incomplete results. Also adds extraction verification and mv/cp fallback logic.

## Changelog:
[Internal] - Fix rncore tarball extraction on EdenFS by extracting to a temp dir first and moving to final location

Author: cipolleschi

packages/react-native/scripts/replace-rncore-version.js

@@ -12,6 +12,8 @@
 
 const {spawnSync} = require('child_process');
 const fs = require('fs');
+const os = require('os');
+const path = require('path');
 const yargs = require('yargs');
 
 const LAST_BUILD_FILENAME = 'React-Core-prebuilt/.last_build_configuration';
@@ -62,14 +64,70 @@ function replaceRNCoreConfiguration(
   const tarballURLPath = `${podsRoot}/ReactNativeCore-artifacts/reactnative-core-${version.toLowerCase()}-${configuration.toLowerCase()}.tar.gz`;
 
   const finalLocation = 'React-Core-prebuilt';
-  console.log('Preparing the final location', finalLocation);
-  fs.rmSync(finalLocation, {force: true, recursive: true});
-  fs.mkdirSync(finalLocation, {recursive: true});
-
-  console.log('Extracting the tarball', tarballURLPath);
-  spawnSync('tar', ['-xf', tarballURLPath, '-C', finalLocation], {
-    stdio: 'inherit',
-  });
+
+  // Extract to a temporary directory on a regular filesystem first, then move
+  // into the final location. This avoids issues with partial tar extraction on
+  // certain filesystems (e.g. EdenFS) where extracting directly can silently
+  // produce incomplete results.
+  const tmpDir = fs.mkdtempSync(path.join(os.tmpdir(), 'rncore-'));
+  const tmpExtractDir = path.join(tmpDir, 'React-Core-prebuilt');
+  fs.mkdirSync(tmpExtractDir, {recursive: true});
+
+  try {
+    console.log('Extracting the tarball to temp dir', tarballURLPath);
+    const result = spawnSync('tar', ['-xf', tarballURLPath, '-C', tmpExtractDir], {
+      stdio: 'inherit',
+    });
+
+    if (result.status !== 0) {
+      throw new Error(
+        `tar extraction failed with exit code ${result.status}`,
+      );
+    }
+
+    // Verify extraction produced the expected xcframework structure
+    const xcfwPath = path.join(tmpExtractDir, 'React.xcframework');
+    const modulemapPath = path.join(
+      xcfwPath,
+      'Modules',
+      'module.modulemap',
+    );
+    if (!fs.existsSync(modulemapPath)) {
+      throw new Error(
+        `Extraction verification failed: ${modulemapPath} not found`,
+      );
+    }
+
+    // Move from temp to final location
+    console.log('Preparing the final location', finalLocation);
+    fs.rmSync(finalLocation, {force: true, recursive: true});
+
+    // Use mv for an atomic-ish replacement. If the final location is on the
+    // same filesystem as tmpDir this is a rename; otherwise it falls back to
+    // copy + delete via spawnSync.
+    const mvResult = spawnSync('mv', [tmpExtractDir, finalLocation], {
+      stdio: 'inherit',
+    });
+
+    if (mvResult.status !== 0) {
+      // Fallback: copy recursively then remove temp
+      console.log('mv failed, falling back to cp -R');
+      fs.mkdirSync(finalLocation, {recursive: true});
+      const cpResult = spawnSync(
+        'cp',
+        ['-R', tmpExtractDir + '/.', finalLocation],
+        {stdio: 'inherit'},
+      );
+      if (cpResult.status !== 0) {
+        throw new Error(
+          `cp fallback failed with exit code ${cpResult.status}`,
+        );
+      }
+    }
+  } finally {
+    // Clean up temp directory
+    fs.rmSync(tmpDir, {force: true, recursive: true});
+  }
 }
 
 function updateLastBuildConfiguration(configuration /*: string */) {