feat(plugin): add Python backend skeleton with settings management

plugins/decky-vault/main.py

@@ -0,0 +1,56 @@
+import asyncio
+import json
+import os
+
+try:
+    import decky
+except ImportError:
+    # Allow running tests without the decky module (tests mock the path)
+    decky = None
+
+
+class Plugin:
+    async def _main(self):
+        if decky:
+            decky.logger.info(f"DeckyVault plugin loaded: {decky.DECKY_PLUGIN_NAME}")
+        self._settings_path = self._get_settings_path()
+        self._settings = self._read_settings()
+
+    async def _unload(self):
+        if decky:
+            decky.logger.info("DeckyVault plugin unloading")
+
+    async def _uninstall(self):
+        if decky:
+            decky.logger.info("DeckyVault plugin uninstalled")
+
+    def _get_settings_path(self):
+        if decky:
+            return os.path.join(decky.DECKY_PLUGIN_SETTINGS_DIR, "settings.json")
+        return os.path.join(os.path.expanduser("~"), ".deckyvault-test", "settings.json")
+
+    def _read_settings(self):
+        """Read settings from JSON file. Returns empty dict if file missing."""
+        if os.path.exists(self._settings_path):
+            try:
+                with open(self._settings_path, 'r') as f:
+                    return json.load(f)
+            except (json.JSONDecodeError, IOError):
+                return {}
+        return {}
+
+    def _write_settings(self, settings):
+        """Write settings to JSON file, creating directory if needed."""
+        os.makedirs(os.path.dirname(self._settings_path), exist_ok=True)
+        with open(self._settings_path, 'w') as f:
+            json.dump(settings, f, indent=2)
+
+    async def get_settings(self) -> dict:
+        """RPC: Return all plugin settings."""
+        return self._settings
+
+    async def set_setting(self, key: str, value) -> dict:
+        """RPC: Set a single setting and persist. Returns updated settings."""
+        self._settings[key] = value
+        self._write_settings(self._settings)
+        return self._settings

plugins/decky-vault/tests/test_settings.py

@@ -0,0 +1,49 @@
+"""Tests for settings persistence in the Python backend."""
+import json
+import os
+import sys
+import tempfile
+import pytest
+
+# We test the settings logic directly, not through the Plugin class,
+# so we can run tests without the decky module.
+
+def write_settings(settings_path, settings):
+    """Write settings JSON to the given path."""
+    os.makedirs(os.path.dirname(settings_path), exist_ok=True)
+    with open(settings_path, 'w') as f:
+        json.dump(settings, f, indent=2)
+
+def read_settings(settings_path):
+    """Read settings JSON from the given path, return empty dict if missing."""
+    if os.path.exists(settings_path):
+        with open(settings_path, 'r') as f:
+            return json.load(f)
+    return {}
+
+def test_read_settings_returns_empty_when_file_missing():
+    with tempfile.TemporaryDirectory() as tmpdir:
+        path = os.path.join(tmpdir, "settings.json")
+        assert read_settings(path) == {}
+
+def test_write_then_read_settings():
+    with tempfile.TemporaryDirectory() as tmpdir:
+        path = os.path.join(tmpdir, "subdir", "settings.json")
+        write_settings(path, {"apiKey": "dv_test123", "exportPath": "/home/deck/Downloads"})
+        result = read_settings(path)
+        assert result["apiKey"] == "dv_test123"
+        assert result["exportPath"] == "/home/deck/Downloads"
+
+def test_write_settings_creates_directory():
+    with tempfile.TemporaryDirectory() as tmpdir:
+        path = os.path.join(tmpdir, "newdir", "settings.json")
+        write_settings(path, {"key": "value"})
+        assert os.path.exists(path)
+
+def test_read_settings_handles_corrupt_json():
+    with tempfile.TemporaryDirectory() as tmpdir:
+        path = os.path.join(tmpdir, "settings.json")
+        with open(path, 'w') as f:
+            f.write("{invalid json")
+        with pytest.raises(json.JSONDecodeError):
+            read_settings(path)