fix: migrate legacy plugins/skills metadata keys to extensions

Add a model_validator that transparently maps the old 'plugins' or
'skills' key to 'extensions' when loading existing .installed.json
files, preserving enabled/disabled state for existing installations.

Co-authored-by: openhands <openhands@all-hands.dev>

Author: csmith49

openhands-sdk/openhands/sdk/extensions/installation/metadata.py

@@ -2,9 +2,9 @@
 
 from pathlib import Path
 from types import TracebackType
-from typing import ClassVar
+from typing import Any, ClassVar
 
-from pydantic import BaseModel, Field
+from pydantic import BaseModel, Field, model_validator
 
 from openhands.sdk.extensions.installation.info import InstallationInfo
 from openhands.sdk.extensions.installation.interface import (
@@ -94,6 +94,18 @@ class InstallationMetadata(BaseModel):
     )
 
     metadata_filename: ClassVar[str] = ".installed.json"
+    _LEGACY_KEYS: ClassVar[tuple[str, ...]] = ("plugins", "skills")
+
+    @model_validator(mode="before")
+    @classmethod
+    def _migrate_legacy_keys(cls, data: Any) -> Any:
+        """Migrate old ``plugins`` / ``skills`` keys to ``extensions``."""
+        if isinstance(data, dict) and "extensions" not in data:
+            for legacy_key in cls._LEGACY_KEYS:
+                if legacy_key in data:
+                    data["extensions"] = data.pop(legacy_key)
+                    break
+        return data
 
     @classmethod
     def open(

tests/sdk/extensions/installation/test_installation_metadata.py

@@ -37,6 +37,67 @@ def _write_mock_extension(
     return directory
 
 
+# ============================================================================
+# Legacy Key Migration Tests
+# ============================================================================
+
+
+def test_migrate_legacy_plugins_key():
+    """Test that old {"plugins": {...}} format is migrated to extensions."""
+    data = {
+        "plugins": {
+            "my-plugin": {
+                "name": "my-plugin",
+                "source": "github:owner/repo",
+                "install_path": "/tmp/installed/my-plugin",
+            }
+        }
+    }
+    metadata = InstallationMetadata.model_validate(data)
+    assert "my-plugin" in metadata.extensions
+    assert metadata.extensions["my-plugin"].name == "my-plugin"
+
+
+def test_migrate_legacy_skills_key():
+    """Test that old {"skills": {...}} format is migrated to extensions."""
+    data = {
+        "skills": {
+            "my-skill": {
+                "name": "my-skill",
+                "source": "local",
+                "install_path": "/tmp/installed/my-skill",
+                "enabled": False,
+            }
+        }
+    }
+    metadata = InstallationMetadata.model_validate(data)
+    assert "my-skill" in metadata.extensions
+    assert metadata.extensions["my-skill"].enabled is False
+
+
+def test_migrate_does_not_overwrite_extensions_key():
+    """Test that migration is skipped when 'extensions' key already exists."""
+    data = {
+        "extensions": {
+            "new-ext": {
+                "name": "new-ext",
+                "source": "local",
+                "install_path": "/tmp/installed/new-ext",
+            }
+        },
+        "plugins": {
+            "old-plugin": {
+                "name": "old-plugin",
+                "source": "local",
+                "install_path": "/tmp/installed/old-plugin",
+            }
+        },
+    }
+    metadata = InstallationMetadata.model_validate(data)
+    assert "new-ext" in metadata.extensions
+    assert "old-plugin" not in metadata.extensions
+
+
 # ============================================================================
 # Load / Save Tests
 # ============================================================================