diff --git a/manifests/install-assets/claude-project-scripts-package.json b/manifests/install-assets/claude-project-scripts-package.json
new file mode 100644
index 000000000..5bbefffba
--- /dev/null
+++ b/manifests/install-assets/claude-project-scripts-package.json
@@ -0,0 +1,3 @@
+{
+  "type": "commonjs"
+}
diff --git a/scripts/lib/install-targets/claude-project.js b/scripts/lib/install-targets/claude-project.js
index a4fda3970..afd413716 100644
--- a/scripts/lib/install-targets/claude-project.js
+++ b/scripts/lib/install-targets/claude-project.js
@@ -9,6 +9,7 @@ const {
 } = require('./helpers');
 
 const CLAUDE_ECC_NAMESPACE = 'ecc';
+const CLAUDE_PROJECT_COMMONJS_PACKAGE = 'manifests/install-assets/claude-project-scripts-package.json';
 
 function getClaudeManagedDestinationPath(adapter, sourceRelativePath, input) {
   const normalizedSourcePath = normalizeRelativePath(sourceRelativePath);
@@ -65,7 +66,7 @@ module.exports = createInstallTargetAdapter({
 
     return modules.flatMap(module => {
       const paths = Array.isArray(module.paths) ? module.paths : [];
-      return paths
+      const operations = paths
         .filter(p => !isForeignPlatformPath(p, 'claude'))
         .flatMap(sourceRelativePath => {
           if (
@@ -93,6 +94,21 @@ module.exports = createInstallTargetAdapter({
 
           return [adapter.createScaffoldOperation(module.id, sourceRelativePath, planningInput)];
         });
+
+      if (module.id !== 'hooks-runtime') {
+        return operations;
+      }
+
+      return [
+        ...['hooks', 'lib'].map(directory => createRemappedOperation(
+          adapter,
+          module.id,
+          CLAUDE_PROJECT_COMMONJS_PACKAGE,
+          path.join(adapter.resolveRoot(planningInput), 'scripts', directory, 'package.json'),
+          { strategy: 'preserve-relative-path' }
+        )),
+        ...operations,
+      ];
     });
   },
 });
diff --git a/tests/scripts/install-apply.test.js b/tests/scripts/install-apply.test.js
index 576ba4389..f2846495f 100644
--- a/tests/scripts/install-apply.test.js
+++ b/tests/scripts/install-apply.test.js
@@ -1056,6 +1056,74 @@ function runTests() {
     }
   })) passed++; else failed++;
 
+  if (test('isolates project hooks from ESM package scopes without overwriting user Claude package data', () => {
+    const homeDir = createTempDir('install-apply-claude-project-esm-home-');
+    const projectDir = createTempDir('install-apply-claude-project-esm-');
+    const claudeRoot = path.join(projectDir, '.claude');
+    const userPackagePath = path.join(claudeRoot, 'package.json');
+    const scriptsPackagePath = path.join(claudeRoot, 'scripts', 'package.json');
+    const hooksPackagePath = path.join(claudeRoot, 'scripts', 'hooks', 'package.json');
+    const libPackagePath = path.join(claudeRoot, 'scripts', 'lib', 'package.json');
+    const userPackage = '{"name":"user-claude-config","type":"module"}\n';
+    const userScriptsPackage = '{"name":"user-claude-scripts","type":"module"}\n';
+
+    try {
+      fs.writeFileSync(path.join(projectDir, 'package.json'), '{"type":"module"}\n');
+      fs.mkdirSync(path.dirname(scriptsPackagePath), { recursive: true });
+      fs.writeFileSync(userPackagePath, userPackage);
+      fs.writeFileSync(scriptsPackagePath, userScriptsPackage);
+
+      const firstInstall = run(
+        ['--target', 'claude-project', '--profile', 'core', '--enable-hooks'],
+        { cwd: projectDir, homeDir }
+      );
+      assert.strictEqual(firstInstall.code, 0, firstInstall.stderr);
+      assert.strictEqual(fs.readFileSync(userPackagePath, 'utf8'), userPackage);
+      assert.strictEqual(fs.readFileSync(scriptsPackagePath, 'utf8'), userScriptsPackage);
+      assert.deepStrictEqual(readJson(hooksPackagePath), { type: 'commonjs' });
+      assert.deepStrictEqual(readJson(libPackagePath), { type: 'commonjs' });
+
+      const hookResult = spawnSync(
+        process.execPath,
+        [path.join(claudeRoot, 'scripts', 'hooks', 'block-no-verify.js')],
+        {
+          input: JSON.stringify({ tool_input: { command: 'git commit --no-verify' } }),
+          encoding: 'utf8',
+          cwd: projectDir,
+        }
+      );
+      assert.strictEqual(hookResult.status, 2, hookResult.stderr);
+      assert.match(hookResult.stderr, /no-verify/i);
+
+      const secondInstall = run(
+        ['--target', 'claude-project', '--profile', 'core', '--enable-hooks'],
+        { cwd: projectDir, homeDir }
+      );
+      assert.strictEqual(secondInstall.code, 0, secondInstall.stderr);
+      assert.strictEqual(fs.readFileSync(userPackagePath, 'utf8'), userPackage);
+      assert.strictEqual(fs.readFileSync(scriptsPackagePath, 'utf8'), userScriptsPackage);
+
+      const state = readJson(path.join(claudeRoot, 'ecc', 'install-state.json'));
+      const boundaryPaths = [hooksPackagePath, libPackagePath];
+      const packageBoundaryOperations = state.operations.filter(operation => (
+        boundaryPaths.includes(operation.destinationPath)
+      ));
+      assert.deepStrictEqual(
+        packageBoundaryOperations.map(operation => operation.destinationPath).sort(),
+        [...boundaryPaths].sort()
+      );
+      assert.ok(packageBoundaryOperations.every(operation => operation.moduleId === 'hooks-runtime'));
+      assert.ok(packageBoundaryOperations.every(operation => (
+        /^[a-f0-9]{64}$/i.test(operation.contentSha256)
+      )));
+      assert.ok(!state.operations.some(operation => operation.destinationPath === userPackagePath));
+      assert.ok(!state.operations.some(operation => operation.destinationPath === scriptsPackagePath));
+    } finally {
+      cleanup(homeDir);
+      cleanup(projectDir);
+    }
+  })) passed++; else failed++;
+
   if (test('preserves existing settings.json while disabling Claude co-author attribution', () => {
     const homeDir = createTempDir('install-apply-home-');
     const projectDir = createTempDir('install-apply-project-');
diff --git a/tests/scripts/uninstall.test.js b/tests/scripts/uninstall.test.js
index 75759969d..a5532a256 100644
--- a/tests/scripts/uninstall.test.js
+++ b/tests/scripts/uninstall.test.js
@@ -132,6 +132,59 @@ function runTests() {
     }
   })) passed++; else failed++;
 
+  if (test('uninstalls the project hook module boundary and preserves user Claude package data', () => {
+    const homeDir = createTempDir('uninstall-claude-project-esm-home-');
+    const projectRoot = createTempDir('uninstall-claude-project-esm-');
+    const claudeRoot = path.join(projectRoot, '.claude');
+    const userPackagePath = path.join(claudeRoot, 'package.json');
+    const scriptsPackagePath = path.join(claudeRoot, 'scripts', 'package.json');
+    const hooksPackagePath = path.join(claudeRoot, 'scripts', 'hooks', 'package.json');
+    const libPackagePath = path.join(claudeRoot, 'scripts', 'lib', 'package.json');
+    const statePath = path.join(claudeRoot, 'ecc', 'install-state.json');
+    const userPackage = '{"name":"user-claude-config","type":"module"}\n';
+    const userScriptsPackage = '{"name":"user-claude-scripts","type":"module"}\n';
+
+    try {
+      fs.writeFileSync(path.join(projectRoot, 'package.json'), '{"type":"module"}\n');
+      fs.mkdirSync(path.dirname(scriptsPackagePath), { recursive: true });
+      fs.writeFileSync(userPackagePath, userPackage);
+      fs.writeFileSync(scriptsPackagePath, userScriptsPackage);
+
+      execFileSync(
+        'node',
+        [INSTALL_SCRIPT, '--target', 'claude-project', '--profile', 'core', '--enable-hooks'],
+        {
+          cwd: projectRoot,
+          env: {
+            ...process.env,
+            HOME: homeDir,
+            USERPROFILE: homeDir,
+          },
+          encoding: 'utf8',
+          stdio: ['pipe', 'pipe', 'pipe'],
+          timeout: CLI_TIMEOUT_MS,
+        }
+      );
+      assert.deepStrictEqual(JSON.parse(fs.readFileSync(hooksPackagePath, 'utf8')), { type: 'commonjs' });
+      assert.deepStrictEqual(JSON.parse(fs.readFileSync(libPackagePath, 'utf8')), { type: 'commonjs' });
+      assert.strictEqual(fs.readFileSync(scriptsPackagePath, 'utf8'), userScriptsPackage);
+
+      const uninstallResult = run(['--target', 'claude-project'], {
+        cwd: projectRoot,
+        homeDir,
+      });
+      assert.strictEqual(uninstallResult.code, 0, uninstallResult.stderr);
+      assert.strictEqual(fs.readFileSync(userPackagePath, 'utf8'), userPackage);
+      assert.strictEqual(fs.readFileSync(scriptsPackagePath, 'utf8'), userScriptsPackage);
+      assert.ok(!fs.existsSync(hooksPackagePath));
+      assert.ok(!fs.existsSync(libPackagePath));
+      assert.ok(!fs.existsSync(statePath));
+    } finally {
+      cleanup(homeDir);
+      cleanup(projectRoot);
+    }
+  })) passed++; else failed++;
+
   if (test('reverses non-copy operations and keeps unrelated files', () => {
     const homeDir = createTempDir('uninstall-home-');
     const projectRoot = createTempDir('uninstall-project-');