diff --git a/scripts/lib/install-targets/antigravity-project.js b/scripts/lib/install-targets/antigravity-project.js
index 2db1af3d..738f32e8 100644
--- a/scripts/lib/install-targets/antigravity-project.js
+++ b/scripts/lib/install-targets/antigravity-project.js
@@ -7,7 +7,7 @@ const {
   normalizeRelativePath,
 } = require('./helpers');
 
-const SUPPORTED_SOURCE_PREFIXES = ['rules', 'commands', 'agents', 'skills', '.agents', 'AGENTS.md'];
+const SUPPORTED_SOURCE_PREFIXES = ['rules', 'commands', 'agents', '.agents', 'AGENTS.md'];
 
 function supportsAntigravitySourcePath(sourceRelativePath) {
   const normalizedPath = normalizeRelativePath(sourceRelativePath);
diff --git a/tests/lib/install-manifests.test.js b/tests/lib/install-manifests.test.js
index 9cbbf6bf..481f0d09 100644
--- a/tests/lib/install-manifests.test.js
+++ b/tests/lib/install-manifests.test.js
@@ -846,7 +846,7 @@ function runTests() {
             id: 'unsupported-antigravity',
             kind: 'skills',
             description: 'Unsupported',
-            paths: ['.cursor', 'skills/example'],
+            paths: ['.cursor', 'skills/example', 'commands/example'],
             targets: ['antigravity'],
             dependencies: [],
             defaultInstall: false,
@@ -875,8 +875,12 @@ function runTests() {
         'Unsupported antigravity paths should be filtered from planned operations'
       );
       assert.ok(
-        plan.operations.some(operation => operation.sourceRelativePath === 'skills/example'),
-        'Supported antigravity skill paths should still be planned'
+        plan.operations.every(operation => operation.sourceRelativePath !== 'skills/example'),
+        'ECC skills should be filtered: antigravity .agent/skills holds ECC agents'
+      );
+      assert.ok(
+        plan.operations.some(operation => operation.sourceRelativePath === 'commands/example'),
+        'Supported antigravity source paths should still be planned'
       );
     } finally {
       cleanupTestRepo(repoRoot);
diff --git a/tests/scripts/install-apply.test.js b/tests/scripts/install-apply.test.js
index 72150314..575bf2a8 100644
--- a/tests/scripts/install-apply.test.js
+++ b/tests/scripts/install-apply.test.js
@@ -580,7 +580,10 @@ function runTests() {
       assert.ok(fs.existsSync(path.join(projectDir, '.agent', 'rules', 'common-coding-style.md')));
       assert.ok(fs.existsSync(path.join(projectDir, '.agent', 'skills', 'architect.md')));
       assert.ok(fs.existsSync(path.join(projectDir, '.agent', 'workflows', 'plan.md')));
-      assert.ok(fs.existsSync(path.join(projectDir, '.agent', 'skills', 'tdd-workflow', 'SKILL.md')));
+      // .agent/skills is where antigravity keeps its agents, and ECC agents are
+      // already mapped there. Installing ECC skills into the same directory made
+      // the two collide, so skills are no longer an antigravity source path.
+      assert.ok(!fs.existsSync(path.join(projectDir, '.agent', 'skills', 'tdd-workflow', 'SKILL.md')));
 
       const state = readJson(path.join(projectDir, '.agent', 'ecc-install-state.json'));
       assert.strictEqual(state.request.profile, 'core');