fix: prevent extension self-install from deleting source dir (#2990)

src/specify_cli/extensions.py

@@ -1333,6 +1333,20 @@ def install_from_directory(
         # Reject manifests that would shadow core commands or installed extensions.
         self._validate_install_conflicts(manifest)
 
+        # Refuse to install an extension from its own install destination — with
+        # --force this would delete the source before copying it (issue #2990).
+        dest_dir = self.extensions_dir / manifest.id
+        try:
+            same_location = source_dir.resolve() == dest_dir.resolve()
+        except OSError:
+            same_location = False
+        if same_location:
+            raise ValidationError(
+                f"Source path is the install destination for '{manifest.id}' "
+                f"({dest_dir}). Refusing to proceed to avoid deleting the "
+                f"extension. Install from a copy in a different location instead."
+            )
+
         # Remove existing installation AFTER all validations pass so that a
         # validation failure doesn't leave the user with a half-uninstalled
         # extension (configs stranded in .backup/).
@@ -1351,8 +1365,7 @@ def install_from_directory(
                 backup_config_dir.unlink()
             did_remove = self.remove(manifest.id)
 
-        # Install extension
-        dest_dir = self.extensions_dir / manifest.id
+        # Install extension (dest_dir computed above during self-install guard)
         if dest_dir.exists():
             shutil.rmtree(dest_dir)
 

tests/test_extensions.py

@@ -1118,6 +1118,29 @@ def test_install_force_without_existing(self, extension_dir, project_dir):
         assert manifest.id == "test-ext"
         assert manager.registry.is_installed("test-ext")
 
+    def test_install_from_install_dir_is_rejected_without_data_loss(
+        self, extension_dir, project_dir
+    ):
+        """Installing from an extension's own install dir must fail without
+        deleting it (regression for issue #2990)."""
+        manager = ExtensionManager(project_dir)
+
+        # Install once so the extension lives at its install destination.
+        manager.install_from_directory(extension_dir, "0.1.0", register_commands=False)
+        install_dir = project_dir / ".specify" / "extensions" / "test-ext"
+        assert install_dir.exists()
+
+        # Re-installing from that same directory with --force must be rejected.
+        with pytest.raises(ValidationError, match="install destination"):
+            manager.install_from_directory(
+                install_dir, "0.1.0", register_commands=False, force=True
+            )
+
+        # The directory and its contents must be left intact (no data loss).
+        assert install_dir.exists()
+        assert (install_dir / "extension.yml").exists()
+        assert (install_dir / "commands" / "hello.md").exists()
+
     def test_install_zip_force_reinstall(self, extension_dir, project_dir):
         """Test force-reinstalling from ZIP when already installed."""
         import zipfile