feat(FN-4723): complete Step 1 — add worktrunk transition classifier

Fusion-Task-Id: FN-4723
Fusion-Task-Lineage: b79b42a0-c65d-4e02-938f-d1ffabc272ee

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

@@ -1,6 +1,10 @@
 import { describe, expect, it } from "vitest";
 import { DEFAULT_GLOBAL_SETTINGS, DEFAULT_PROJECT_SETTINGS } from "../settings-schema.js";
-import { resolveWorktrunkSettings, validateWorktrunkSettings } from "../worktrunk-settings.js";
+import {
+  resolveWorktrunkSettings,
+  requiresWorktrunkInstallVerification,
+  validateWorktrunkSettings,
+} from "../worktrunk-settings.js";
 
 describe("settings defaults invariants", () => {
   it("keeps worktrunk default off in global and project defaults", () => {
@@ -25,4 +29,15 @@ describe("settings defaults invariants", () => {
   it("does not implicitly enable worktrunk when validating undefined", () => {
     expect(validateWorktrunkSettings(undefined)).toEqual({});
   });
+
+  it("flags off→on transition from fresh defaults", () => {
+    const freshProject = resolveWorktrunkSettings(DEFAULT_GLOBAL_SETTINGS.worktrunk, DEFAULT_PROJECT_SETTINGS.worktrunk);
+    expect(freshProject.enabled).toBe(false);
+    expect(
+      requiresWorktrunkInstallVerification({
+        current: freshProject,
+        next: { ...freshProject, enabled: true },
+      }),
+    ).toBe(true);
+  });
 });

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

@@ -2,6 +2,7 @@ import { describe, expect, it } from "vitest";
 
 import {
   resolveWorktrunkSettings,
+  requiresWorktrunkInstallVerification,
   validateWorktrunkSettings,
 } from "../worktrunk-settings.js";
 
@@ -40,6 +41,14 @@ describe("worktrunk-settings", () => {
     });
   });
 
+  it("classifies enable transitions that require install verification", () => {
+    expect(requiresWorktrunkInstallVerification({ current: { enabled: false }, next: { enabled: true } })).toBe(true);
+    expect(requiresWorktrunkInstallVerification({ current: { enabled: true }, next: { enabled: true } })).toBe(false);
+    expect(requiresWorktrunkInstallVerification({ current: { enabled: true }, next: { enabled: false } })).toBe(false);
+    expect(requiresWorktrunkInstallVerification({ current: undefined, next: undefined })).toBe(false);
+    expect(requiresWorktrunkInstallVerification({ current: undefined, next: { enabled: true } })).toBe(true);
+  });
+
   it("validator rejects invalid values", () => {
     expect(() => validateWorktrunkSettings({ onFailure: "ignore" })).toThrow(
       "worktrunk.onFailure must be one of",