ui improvements on error when registering repos

tests/test_web_api.py

@@ -1073,6 +1073,7 @@ def test_ui_register_analyze_and_approve_loop(tmp_path):
         index_response = client.get("/ui")
         assert index_response.status_code == 200
         assert "Register Repository" in index_response.text
+        assert "Registering repository..." in index_response.text
 
         create_response = client.post(
             "/ui/repos",
@@ -1201,6 +1202,32 @@ def test_ui_register_analyze_and_approve_loop(tmp_path):
         app.dependency_overrides.clear()
 
 
+def test_ui_registration_failure_returns_feedback(tmp_path):
+    def override_settings():
+        return Settings(
+            database_path=str(tmp_path / "ui-error.sqlite3"),
+            checkout_root=str(tmp_path / "ui-error-checkouts"),
+        )
+
+    app.dependency_overrides[get_settings] = override_settings
+    client = TestClient(app)
+    try:
+        response = client.post(
+            "/ui/repos",
+            data={
+                "url": str(tmp_path / "missing-repo"),
+                "branch": "main",
+            },
+        )
+
+        assert response.status_code == 400
+        assert "Registration failed." in response.text
+        assert "git clone" in response.text
+        assert "Register Repository" in response.text
+    finally:
+        app.dependency_overrides.clear()
+
+
 def test_ui_manual_registry_entry_loop(tmp_path):
     source = tmp_path / "manual-repo"
     source.mkdir()