feat(server): Group CRUD with JSON persistence and bulk actions (TDD)

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

server/group_store.py

@@ -0,0 +1,101 @@
+"""Singleton store for service groups with JSON file persistence.
+
+Groups are persisted to a JSON file specified by the ``GROUPS_PATH``
+environment variable (default ``/app/groups.json``).
+"""
+
+import json
+import os
+import threading
+
+from server.models import Group, GroupsData
+
+
+class GroupStore:
+    """Thread-safe singleton that manages groups and persists to disk."""
+
+    _instance: "GroupStore | None" = None
+    _lock = threading.Lock()
+
+    def __new__(cls) -> "GroupStore":
+        with cls._lock:
+            if cls._instance is None:
+                cls._instance = super().__new__(cls)
+                cls._instance._initialized = False
+            return cls._instance
+
+    def __init__(self) -> None:
+        if self._initialized:
+            return
+        self._initialized = True
+        self._data_lock = threading.Lock()
+        self._path = os.environ.get("GROUPS_PATH", "/app/groups.json")
+        self._groups: list[Group] = []
+        self._load()
+
+    # ------------------------------------------------------------------
+    # Persistence
+    # ------------------------------------------------------------------
+
+    def _load(self) -> None:
+        """Load groups from the JSON file on disk."""
+        try:
+            with open(self._path) as f:
+                raw = json.load(f)
+            data = GroupsData(**raw)
+            self._groups = data.groups
+        except (FileNotFoundError, json.JSONDecodeError):
+            self._groups = []
+
+    def _save(self) -> None:
+        """Persist the current groups list to the JSON file."""
+        data = GroupsData(groups=self._groups)
+        with open(self._path, "w") as f:
+            json.dump(data.model_dump(), f, indent=2)
+
+    # ------------------------------------------------------------------
+    # CRUD operations
+    # ------------------------------------------------------------------
+
+    def list_groups(self) -> list[Group]:
+        """Return all groups."""
+        with self._data_lock:
+            return list(self._groups)
+
+    def get_group(self, group_id: str) -> Group | None:
+        """Return a single group by id, or None."""
+        with self._data_lock:
+            for g in self._groups:
+                if g.id == group_id:
+                    return g
+            return None
+
+    def create_group(self, group: Group) -> Group:
+        """Add a new group. Raises ValueError if duplicate id."""
+        with self._data_lock:
+            for g in self._groups:
+                if g.id == group.id:
+                    raise ValueError(f"Group '{group.id}' already exists")
+            self._groups.append(group)
+            self._save()
+            return group
+
+    def update_group(self, group_id: str, group: Group) -> Group | None:
+        """Replace a group by id. Returns updated group or None."""
+        with self._data_lock:
+            for i, g in enumerate(self._groups):
+                if g.id == group_id:
+                    self._groups[i] = group
+                    self._save()
+                    return group
+            return None
+
+    def delete_group(self, group_id: str) -> bool:
+        """Remove a group by id. Returns True if found and deleted."""
+        with self._data_lock:
+            for i, g in enumerate(self._groups):
+                if g.id == group_id:
+                    self._groups.pop(i)
+                    self._save()
+                    return True
+            return False