feat: add the operations layer for declared plugin actions

src/backend/operations/key-scopes.ts

@@ -0,0 +1,44 @@
+/**
+ * What a scoped API key may reach. Enforced where keys are authenticated, so a
+ * limited key cannot step around the gate through /plugin-api or a ws ticket. A
+ * key with no scopes has full access, which is every key made before this.
+ */
+
+export const API_KEY_SCOPES = ["operations:read", "operations:run"] as const;
+
+const MCP_PATH = /^\/plugin-api\/[a-z0-9-]+\/mcp(\/|$)/;
+const OPERATIONS_PATH = /^\/operations(\/|$)/;
+
+export function parseKeyScopes(
+  raw: string | null | undefined,
+): string[] | null {
+  if (!raw) return null;
+  try {
+    const value = JSON.parse(raw);
+    return Array.isArray(value)
+      ? value.filter((scope): scope is string => typeof scope === "string")
+      : [];
+  } catch {
+    // Unreadable means no access, not full access.
+    return [];
+  }
+}
+
+export function keyScopeAllows(
+  scopes: string[] | null,
+  method: string,
+  path: string,
+): boolean {
+  if (scopes === null) return true;
+  const clean = path.split("?")[0];
+  if (MCP_PATH.test(clean)) {
+    return (
+      scopes.includes("operations:read") || scopes.includes("operations:run")
+    );
+  }
+  if (!OPERATIONS_PATH.test(clean)) return false;
+  if (scopes.includes("operations:run")) return true;
+  if (!scopes.includes("operations:read")) return false;
+  // The gate still checks each action's risk on a run.
+  return method === "GET" || /^\/operations\/[^/]+\/run$/.test(clean);
+}