feat(FN-4650): complete Step 1 — add sandbox experimental helper

Fusion-Task-Id: FN-4650
Fusion-Task-Lineage: 3da8db80-236b-46f6-8122-644abda35ca3

packages/core/src/__tests__/sandbox-settings.test.ts

@@ -5,6 +5,7 @@ import {
   PROJECT_SETTINGS_KEYS,
   SANDBOX_BACKEND_NAMES,
   SANDBOX_FAILURE_MODES,
+  isSandboxExperimentalEnabled,
   validateSandboxBackendName,
   validateSandboxFailureMode,
   validateSandboxPolicy,
@@ -102,4 +103,22 @@ describe("sandbox settings", () => {
       expect(validateSandboxProjectSettings("nope")).toBeUndefined();
     });
   });
+
+  describe("isSandboxExperimentalEnabled", () => {
+    it("returns false for undefined settings", () => {
+      expect(isSandboxExperimentalEnabled(undefined)).toBe(false);
+    });
+
+    it("returns false when sandbox flag is missing", () => {
+      expect(isSandboxExperimentalEnabled({ experimentalFeatures: {} })).toBe(false);
+    });
+
+    it("returns false when sandbox flag is false", () => {
+      expect(isSandboxExperimentalEnabled({ experimentalFeatures: { sandbox: false } })).toBe(false);
+    });
+
+    it("returns true when sandbox flag is true", () => {
+      expect(isSandboxExperimentalEnabled({ experimentalFeatures: { sandbox: true } })).toBe(true);
+    });
+  });
 });

packages/core/src/index.ts

@@ -877,6 +877,7 @@ export { isExperimentalFeatureEnabled } from "./experimental-features.js";
 export { isResearchExperimentalEnabled, resolveResearchSettings } from "./research-settings.js";
 export type { ResolvedResearchSettings } from "./research-settings.js";
 export { isEvalsExperimentalEnabled, resolveEvalSettings } from "./eval-settings.js";
+export { isSandboxExperimentalEnabled } from "./sandbox-settings.js";
 
 export { TodoStore } from "./todo-store.js";
 export type { TodoStoreEvents } from "./todo-store.js";

packages/core/src/sandbox-settings.ts

@@ -0,0 +1,6 @@
+import { isExperimentalFeatureEnabled } from "./experimental-features.js";
+import type { Settings } from "./types.js";
+
+export function isSandboxExperimentalEnabled(settings: Partial<Settings> | undefined): boolean {
+  return isExperimentalFeatureEnabled(settings, "sandbox");
+}