fix: address greptile routine review

ui/src/lib/routine-trigger-patch.test.ts

@@ -0,0 +1,71 @@
+import { describe, expect, it } from "vitest";
+import type { RoutineTrigger } from "@paperclipai/shared";
+import { buildRoutineTriggerPatch } from "./routine-trigger-patch";
+
+function makeScheduleTrigger(overrides: Partial<RoutineTrigger> = {}): RoutineTrigger {
+  return {
+    id: "trigger-1",
+    companyId: "company-1",
+    routineId: "routine-1",
+    kind: "schedule",
+    label: "Daily",
+    enabled: true,
+    cronExpression: "0 10 * * *",
+    timezone: "UTC",
+    nextRunAt: null,
+    lastFiredAt: null,
+    publicId: null,
+    secretId: null,
+    signingMode: null,
+    replayWindowSec: null,
+    lastRotatedAt: null,
+    lastResult: null,
+    createdByAgentId: null,
+    createdByUserId: null,
+    updatedByAgentId: null,
+    updatedByUserId: null,
+    createdAt: new Date("2026-03-20T00:00:00.000Z"),
+    updatedAt: new Date("2026-03-20T00:00:00.000Z"),
+    ...overrides,
+  };
+}
+
+describe("buildRoutineTriggerPatch", () => {
+  it("preserves an existing schedule trigger timezone when saving edits", () => {
+    const patch = buildRoutineTriggerPatch(
+      makeScheduleTrigger({ timezone: "UTC" }),
+      {
+        label: "Daily label edit",
+        cronExpression: "0 10 * * *",
+        signingMode: "bearer",
+        replayWindowSec: "300",
+      },
+      "America/Chicago",
+    );
+
+    expect(patch).toEqual({
+      label: "Daily label edit",
+      cronExpression: "0 10 * * *",
+      timezone: "UTC",
+    });
+  });
+
+  it("falls back to the local timezone when a schedule trigger has none", () => {
+    const patch = buildRoutineTriggerPatch(
+      makeScheduleTrigger({ timezone: null }),
+      {
+        label: "",
+        cronExpression: "15 9 * * 1-5",
+        signingMode: "bearer",
+        replayWindowSec: "300",
+      },
+      "America/Chicago",
+    );
+
+    expect(patch).toEqual({
+      label: null,
+      cronExpression: "15 9 * * 1-5",
+      timezone: "America/Chicago",
+    });
+  });
+});