@@ -51,6 +51,7 @@ import { ScreenScrollView as ScrollView } from "../../components/ui/ScreenScroll
 import { SegmentedControl } from "../../components/ui/SegmentedControl";
 import { ThemedSwitch } from "../../components/ui/ThemedSwitch";
 import { webhookAddress } from "@t3tools/client-runtime/webhook-address";
+import { localTimeZone, parseTimeZoneDraft } from "@t3tools/client-runtime/scheduled-task-schedule";
 import { tryCopyTextWithHaptic } from "../../lib/copyTextWithHaptic";
 import { usePreparedConnection } from "../../state/session";
 import { buildModelOptions } from "../../lib/modelOptions";
@@ -106,7 +107,8 @@ function describeSchedule(task: ScheduledTask): string {
   if (task.schedule.type === "webhook") return "On webhook";
   if (task.schedule.type === "interval") return formatScheduledTaskInterval(task.schedule.everyMs);
   const days = task.schedule.weekdays?.length ? repeatLabel(task.schedule.weekdays) : "Every day";
-  return `${days} at ${formatTime(task.schedule.timeOfDay)}`;
+  const zone = task.schedule.timeZone ? ` (${task.schedule.timeZone})` : "";
+  return `${days} at ${formatTime(task.schedule.timeOfDay)}${zone}`;
 }
 
 function formatTime(value: string): string {
@@ -148,6 +150,8 @@ function FormField(props: {
   readonly disabled?: boolean;
   readonly placeholder?: string;
   readonly borderTop?: boolean;
+  /** For identifiers such as time zone names, which autocorrect would mangle. */
+  readonly literal?: boolean;
 }) {
   return (
     <View
@@ -163,6 +167,8 @@ function FormField(props: {
         onChangeText={props.onChange}
         textAlignVertical="center"
         keyboardType={props.keyboardType}
+        autoCapitalize={props.literal ? "none" : undefined}
+        autoCorrect={props.literal ? false : undefined}
         placeholder={props.placeholder}
         placeholderTextColorClassName="accent-foreground-muted"
         className="min-h-8 font-sans text-base text-foreground"
@@ -711,6 +717,16 @@ function TaskForm({
       );
       return;
     }
+    if (
+      draft.schedule.mode === "fixed_time" &&
+      parseTimeZoneDraft(draft.schedule.timeZone) === undefined
+    ) {
+      Dialog.alert(
+        "Unknown time zone",
+        "Enter a time zone such as America/Chicago, or leave it blank.",
+      );
+      return;
+    }
     const parsedFilters = parseWebhookFilterDrafts(draft.schedule.filters);
     if (draft.schedule.mode === "webhook" && "error" in parsedFilters) {
       Dialog.alert("Invalid filter", parsedFilters.error);
@@ -1034,6 +1050,17 @@ function TaskForm({
                   setDraft({ ...draft, schedule: { ...draft.schedule, weekdays } });
                 }}
               />
+              <FormField
+                label="Time zone"
+                value={draft.schedule.timeZone}
+                placeholder="Environment's time zone"
+                disabled={saving}
+                borderTop
+                literal
+                onChange={(timeZone) =>
+                  setDraft({ ...draft, schedule: { ...draft.schedule, timeZone } })
+                }
+              />
             </>
           ) : draft.schedule.mode === "webhook" ? (
             <>
@@ -1139,7 +1166,8 @@ function TaskForm({
         </SettingsSection>
         {draft.schedule.mode === "fixed_time" ? (
           <Text className="px-2 text-sm text-foreground-muted">
-            Time uses the environment's time zone, which may differ from your phone's.
+            Enter an IANA time zone such as {localTimeZone()}, this phone's. Left blank, the time
+            uses the environment's time zone, which may differ from your phone's.
           </Text>
         ) : null}
       </View>
 
@@ -87,6 +87,22 @@ describe("scheduleFromDraft", () => {
     expect(scheduleFromDraft({ ...DEFAULT_SCHEDULE, weekdays: [] })).toBeNull();
   });
 
+  it("keeps a fixed time's zone, clears it when blank, and rejects an unknown one", () => {
+    const draft = scheduleDraftForTask({
+      schedule: { type: "fixed_time", timeOfDay: "09:00", timeZone: "America/Chicago" },
+    });
+    expect(scheduleFromDraft(draft)).toEqual({
+      type: "fixed_time",
+      timeOfDay: "09:00",
+      timeZone: "America/Chicago",
+    });
+    expect(scheduleFromDraft({ ...draft, timeZone: "america/chicago" })).toMatchObject({
+      timeZone: "America/Chicago",
+    });
+    expect(scheduleFromDraft({ ...draft, timeZone: "" })).toMatchObject({ timeZone: null });
+    expect(scheduleFromDraft({ ...draft, timeZone: "Chicago" })).toBeNull();
+  });
+
   it.each([
     ["1.5", 90_000],
     [String(60_001 / 60_000), 60_001],
 
@@ -17,6 +17,7 @@ import {
   webhookFilterDraftsChanged,
   type WebhookFilterDraft,
 } from "@t3tools/client-runtime/scheduled-task-webhook";
+import { parseTimeZoneDraft } from "@t3tools/client-runtime/scheduled-task-schedule";
 import {
   resolveProjectSettings,
   type LegacyProjectSettingsFields,
@@ -54,6 +55,8 @@ export type ScheduleDraft = {
   readonly mode: "fixed_time" | "interval" | "webhook";
   readonly timeOfDay: string;
   readonly weekdays: ReadonlyArray<number>;
+  /** Blank runs at the environment's local time. */
+  readonly timeZone: string;
   readonly intervalMinutes: string;
   readonly signature: ScheduledTaskWebhookSignature | null;
   readonly maxDeliveryAgeMinutes: string;
@@ -69,6 +72,7 @@ export const DEFAULT_SCHEDULE: ScheduleDraft = {
   mode: "fixed_time",
   timeOfDay: "09:00",
   weekdays: [1, 2, 3, 4, 5],
+  timeZone: "",
   intervalMinutes: "15",
   signature: null,
   maxDeliveryAgeMinutes: "",
@@ -88,6 +92,7 @@ export function scheduleDraftForTask(task: Pick<ScheduledTask, "schedule">): Sch
         weekdays: task.schedule.weekdays?.length
           ? [...new Set(task.schedule.weekdays)].sort((a, b) => a - b)
           : [0, 1, 2, 3, 4, 5, 6],
+        timeZone: task.schedule.timeZone ?? "",
       };
     case "interval":
       return {
@@ -168,7 +173,9 @@ export function scheduleFromDraft(draft: ScheduleDraft): ScheduledTaskUpsertSche
     return minutes >= 1 && Number.isSafeInteger(everyMs) ? { type: "interval", everyMs } : null;
   }
   const weekdays = [...new Set(draft.weekdays)].sort((a, b) => a - b);
+  const timeZone = parseTimeZoneDraft(draft.timeZone);
   if (
+    timeZone === undefined ||
     !/^([01]?\d|2[0-3]):[0-5]\d$/.test(draft.timeOfDay) ||
     weekdays.length === 0 ||
     weekdays.some((day) => !Number.isInteger(day) || day < 0 || day > 6)
@@ -179,6 +186,7 @@ export function scheduleFromDraft(draft: ScheduleDraft): ScheduledTaskUpsertSche
     type: "fixed_time",
     timeOfDay: draft.timeOfDay,
     ...(weekdays.length === 7 ? {} : { weekdays }),
+    timeZone,
   };
 }
 
@@ -212,6 +220,7 @@ function draftSignature(draft: ScheduledTaskDraft): string {
     draft.schedule.mode,
     draft.schedule.timeOfDay,
     [...draft.schedule.weekdays].sort((a, b) => a - b),
+    draft.schedule.timeZone,
     draft.schedule.intervalMinutes,
     draft.schedule.maxDeliveryAgeMinutes,
     draft.schedule.replayKey,
 
@@ -118,7 +118,7 @@ const WorkflowStopTool = Tool.make("t3_workflow_stop", {
 
 const ScheduleTaskTool = Tool.make("schedule_task", {
   description:
-    "Create persistent work in the app scheduler that runs even when no turn is active. Pass schedule as a STRUCTURED OBJECT, never JSON text. Timers: {type:'interval', everyMs:3600000} is hourly; {type:'fixed_time', timeOfDay:'09:00', weekdays:[1,2,3,4,5]} is weekday mornings; report the returned nextRunAt. Webhook dedupe accepts replayKey and coalesceKey templates with coalesceWindowSeconds (10–3600, default 120); replay keys expire after 7 days and coalescing keeps the latest payload in a window measured from its first delivery. Webhooks: {type:'webhook'} runs once per request to a generated URL. The run sees the request ONLY through prompt placeholders: {{body.path}} (e.g. {{body.action}}, {{body.release.tag_name}}), {{headers.name}}, {{query.name}}, {{body}}, or {{request}} (method, headers with credentials redacted, and body). Each value arrives framed as untrusted request data, and $skill, @file or /command mentions inside it do not act; without a signature, anyone with the URL can trigger a run. For a sender that signs requests, first call request_secret so the user enters the secret privately (never ask for it in chat or invent one), then set signature with the returned secretRef, e.g. GitHub: {type:'webhook', signature:{header:'x-hub-signature-256', encoding:'hex', prefix:'sha256=', secretRef}}. To run only for some requests, add filters, all of which must match, e.g. filters:[{path:'headers.x-github-event', op:'equals', value:'pull_request'}, {path:'body.action', op:'in', value:['opened','reopened']}]; ops are equals, notEquals, in, startsWith and exists. A path segment ending in [] fans out over an array: {path:'body.issue.labels[].name', op:'equals', value:'needs more info'} matches when any label has that name, and notEquals only when none does. The result's webhookUrl is the public URL to give the user; if it is absent, this environment has no T3 Connect managed tunnel, so tell the user to enable T3 Connect remote access rather than sharing a path. Omit projectId for this thread's project. In this thread's project, runs post into THIS thread by default (bindToCurrentThread=true), which suits an orchestrator that sees every trigger, delegates work, and can dedupe against what is in flight; use false only when the user wants a fresh top-level thread per run. Elsewhere each run launches a fresh thread. Provider, model, and runtime settings inherit from this thread, or from the project default when there is no calling thread.",
+    "Create persistent work in the app scheduler that runs even when no turn is active. Pass schedule as a STRUCTURED OBJECT, never JSON text. Timers: {type:'interval', everyMs:3600000} is hourly; {type:'fixed_time', timeOfDay:'09:00', weekdays:[1,2,3,4,5]} is weekday mornings; report the returned nextRunAt. A fixed time uses the environment's local clock unless you add timeZone, an IANA name such as 'America/Chicago'; add it when the user names a zone or a city, so daylight-saving changes follow their clock. Webhook dedupe accepts replayKey and coalesceKey templates with coalesceWindowSeconds (10–3600, default 120); replay keys expire after 7 days and coalescing keeps the latest payload in a window measured from its first delivery. Webhooks: {type:'webhook'} runs once per request to a generated URL. The run sees the request ONLY through prompt placeholders: {{body.path}} (e.g. {{body.action}}, {{body.release.tag_name}}), {{headers.name}}, {{query.name}}, {{body}}, or {{request}} (method, headers with credentials redacted, and body). Each value arrives framed as untrusted request data, and $skill, @file or /command mentions inside it do not act; without a signature, anyone with the URL can trigger a run. For a sender that signs requests, first call request_secret so the user enters the secret privately (never ask for it in chat or invent one), then set signature with the returned secretRef, e.g. GitHub: {type:'webhook', signature:{header:'x-hub-signature-256', encoding:'hex', prefix:'sha256=', secretRef}}. To run only for some requests, add filters, all of which must match, e.g. filters:[{path:'headers.x-github-event', op:'equals', value:'pull_request'}, {path:'body.action', op:'in', value:['opened','reopened']}]; ops are equals, notEquals, in, startsWith and exists. A path segment ending in [] fans out over an array: {path:'body.issue.labels[].name', op:'equals', value:'needs more info'} matches when any label has that name, and notEquals only when none does. The result's webhookUrl is the public URL to give the user; if it is absent, this environment has no T3 Connect managed tunnel, so tell the user to enable T3 Connect remote access rather than sharing a path. Omit projectId for this thread's project. In this thread's project, runs post into THIS thread by default (bindToCurrentThread=true), which suits an orchestrator that sees every trigger, delegates work, and can dedupe against what is in flight; use false only when the user wants a fresh top-level thread per run. Elsewhere each run launches a fresh thread. Provider, model, and runtime settings inherit from this thread, or from the project default when there is no calling thread.",
   parameters: OrchestratorMcpScheduleTaskInput,
   success: OrchestratorMcpScheduleTaskResult,
   failure: OrchestratorMcpFailure,
@@ -145,7 +145,7 @@ const ListScheduledTasksTool = Tool.make("list_scheduled_tasks", {
 
 const UpdateScheduledTaskTool = Tool.make("update_scheduled_task", {
   description:
-    "Update an existing scheduled task by scheduledTaskId (from list_scheduled_tasks). Webhook schedule dedupe accepts replayKey, coalesceKey, and coalesceWindowSeconds (10–3600, default 120) to suppress replays for 7 days and retain the latest payload in each fixed window. Only the provided fields change; omit a field to leave it as-is. Use enabled=false to pause a task without deleting it. Set bindToCurrentThread to move the task between posting into this thread and launching a fresh thread per run. A webhook schedule without filters keeps the stored filters; pass filters to replace them, or filters:[] to clear them.",
+    "Update an existing scheduled task by scheduledTaskId (from list_scheduled_tasks). Webhook schedule dedupe accepts replayKey, coalesceKey, and coalesceWindowSeconds (10–3600, default 120) to suppress replays for 7 days and retain the latest payload in each fixed window. Only the provided fields change; omit a field to leave it as-is. The same holds inside schedule: an optional field such as timeZone that you leave out keeps its stored value, and null removes it. Use enabled=false to pause a task without deleting it. Set bindToCurrentThread to move the task between posting into this thread and launching a fresh thread per run. A webhook schedule without filters keeps the stored filters; pass filters to replace them, or filters:[] to clear them.",
   parameters: OrchestratorMcpUpdateScheduledTaskInput,
   success: OrchestratorMcpScheduleTaskResult,
   failure: OrchestratorMcpFailure,
 
@@ -1,4 +1,5 @@
 import { describe, expect, it } from "@effect/vitest";
+import type { ScheduledTaskSchedule } from "@t3tools/contracts";
 import * as DateTime from "effect/DateTime";
 
 import { isSameSchedule, nextScheduledRunAt } from "./Schedule.ts";
@@ -26,6 +27,61 @@ describe("scheduled task schedule calculation", () => {
     expect(parts?.minute).toBe(0);
   });
 
+  describe("fixed time in a time zone", () => {
+    const next = (
+      schedule: Partial<Extract<ScheduledTaskSchedule, { type: "fixed_time" }>>,
+      from: string,
+    ) => {
+      const run = nextScheduledRunAt(
+        { type: "fixed_time", timeOfDay: "09:00", timeZone: "America/Chicago", ...schedule },
+        DateTime.makeUnsafe(from),
+      );
+      return run === null ? null : DateTime.formatIso(DateTime.toUtc(run));
+    };
+
+    it("runs at the wall-clock time of its zone, not the server's", () => {
+      expect(next({}, "2026-07-03T10:00:00.000Z")).toBe("2026-07-03T14:00:00.000Z");
+      expect(next({ timeZone: "Asia/Tokyo" }, "2026-07-03T10:00:00.000Z")).toBe(
+        "2026-07-04T00:00:00.000Z",
+      );
+    });
+
+    it("keeps the wall-clock time across the spring-forward change", () => {
+      // 09:00 CST is 15:00Z; after clocks move forward on March 8, 09:00 CDT is 14:00Z.
+      expect(next({}, "2026-03-07T16:00:00.000Z")).toBe("2026-03-08T14:00:00.000Z");
+      // 02:30 does not exist on March 8, so that run moves to 03:30 CDT.
+      expect(next({ timeOfDay: "02:30" }, "2026-03-08T07:00:00.000Z")).toBe(
+        "2026-03-08T08:30:00.000Z",
+      );
+      expect(next({ timeOfDay: "02:30" }, "2026-03-08T08:31:00.000Z")).toBe(
+        "2026-03-09T07:30:00.000Z",
+      );
+    });
+
+    it("keeps the wall-clock time across the fall-back change and runs a repeated time once", () => {
+      // 09:00 CDT is 14:00Z; after clocks move back on November 1, 09:00 CST is 15:00Z.
+      expect(next({}, "2026-10-31T15:00:00.000Z")).toBe("2026-11-01T15:00:00.000Z");
+      // 01:30 happens twice on November 1: first in CDT (06:30Z), then in CST (07:30Z).
+      expect(next({ timeOfDay: "01:30" }, "2026-11-01T05:00:00.000Z")).toBe(
+        "2026-11-01T06:30:00.000Z",
+      );
+      expect(next({ timeOfDay: "01:30" }, "2026-11-01T06:31:00.000Z")).toBe(
+        "2026-11-02T07:30:00.000Z",
+      );
+    });
+
+    it("applies weekdays in the zone's calendar", () => {
+      // Friday 20:00 in Chicago is already Saturday in UTC.
+      expect(next({ timeOfDay: "20:00", weekdays: [5] }, "2026-07-03T12:00:00.000Z")).toBe(
+        "2026-07-04T01:00:00.000Z",
+      );
+    });
+
+    it("has no next run for a zone this runtime does not know", () => {
+      expect(next({ timeZone: "Mars/Olympus_Mons" }, "2026-07-03T10:00:00.000Z")).toBeNull();
+    });
+  });
+
   it("compares schedules structurally", () => {
     expect(
       isSameSchedule({ type: "interval", everyMs: 60_000 }, { type: "interval", everyMs: 60_000 }),
@@ -75,5 +131,11 @@ describe("scheduled task schedule calculation", () => {
         { type: "fixed_time", timeOfDay: "09:00" },
       ),
     ).toBe(false);
+    expect(
+      isSameSchedule(
+        { type: "fixed_time", timeOfDay: "09:00", timeZone: "America/Chicago" },
+        { type: "fixed_time", timeOfDay: "09:00" },
+      ),
+    ).toBe(false);
   });
 });