feat(plugins): discover packages and persist state

app-instance/backend/beaver/plugins/state.py

@@ -0,0 +1,78 @@
+"""Atomic state persistence for declarative plugins."""
+
+from __future__ import annotations
+
+import json
+import os
+from pathlib import Path
+from typing import Any
+
+from .models import PluginSkillBinding, PluginState
+
+
+class PluginStateStore:
+    def __init__(self, workspace: str | Path) -> None:
+        self.workspace = Path(workspace)
+        self.root = self.workspace / ".beaver" / "plugins"
+        self.path = self.root / "state.json"
+
+    def list_plugins(self) -> list[PluginState]:
+        return [
+            PluginState.from_dict(plugin_id, payload if isinstance(payload, dict) else {})
+            for plugin_id, payload in sorted(self._read_state().get("plugins", {}).items())
+        ]
+
+    def get_plugin(self, plugin_id: str) -> PluginState | None:
+        payload = self._read_state().get("plugins", {}).get(plugin_id)
+        if not isinstance(payload, dict):
+            return None
+        return PluginState.from_dict(plugin_id, payload)
+
+    def set_enabled(self, plugin_id: str, enabled: bool) -> PluginState:
+        state = self.get_plugin(plugin_id) or PluginState(plugin_id=plugin_id)
+        state.enabled = enabled
+        if enabled and state.status == "discovered":
+            state.status = "enabled"
+        self.upsert_plugin(state)
+        return state
+
+    def upsert_plugin(self, plugin_state: PluginState) -> None:
+        state = self._read_state()
+        plugins = state.setdefault("plugins", {})
+        if not isinstance(plugins, dict):
+            plugins = {}
+            state["plugins"] = plugins
+        plugins[plugin_state.plugin_id] = plugin_state.to_dict()
+        self._write_state(state)
+
+    def update_skill_binding(
+        self,
+        plugin_id: str,
+        skill_name: str,
+        binding: PluginSkillBinding,
+    ) -> PluginState:
+        state = self.get_plugin(plugin_id) or PluginState(plugin_id=plugin_id)
+        state.skills[skill_name] = binding
+        self.upsert_plugin(state)
+        return state
+
+    def _read_state(self) -> dict[str, Any]:
+        if not self.path.exists():
+            return {"plugins": {}}
+        payload = json.loads(self.path.read_text(encoding="utf-8"))
+        if not isinstance(payload, dict):
+            return {"plugins": {}}
+        plugins = payload.get("plugins")
+        if not isinstance(plugins, dict):
+            payload["plugins"] = {}
+        return payload
+
+    def _write_state(self, state: dict[str, Any]) -> None:
+        self.root.mkdir(parents=True, exist_ok=True)
+        tmp_path = self.path.with_name("state.json.tmp")
+        with tmp_path.open("w", encoding="utf-8") as handle:
+            json.dump(state, handle, ensure_ascii=False, sort_keys=True, indent=2)
+            handle.write("\n")
+            handle.flush()
+            os.fsync(handle.fileno())
+        os.replace(tmp_path, self.path)