fix(schedule): limit to 24 hours ahead with a clear message (#275)

Production Synapse caps delayed events at 24h, but the dialog let any
later time be picked and then showed the raw server error. The date
input now has min/max (today .. now+24h), a too-late time shows "You can
schedule up to 24 hours ahead." as soon as it is picked (and blocks
Schedule), and ORG.MATRIX.MSC4140_DELAY_TOO_LARGE maps to the same text.

Fixes #275

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_017PCb59uY3UKqDqt7B6hzd5

src/app/features/room/ScheduleMessageModal.tsx

@@ -20,7 +20,12 @@ import { IContent } from 'matrix-js-sdk';
 import { useTimestampFormatter } from '../../hooks/useTimestampFormatter';
 import { useMatrixClient } from '../../hooks/useMatrixClient';
 import { stopPropagation } from '../../utils/keyboard';
-import { scheduleMessage } from '../../utils/scheduledMessages';
+import {
+  describeScheduleError,
+  MAX_SCHEDULE_AHEAD_MS,
+  scheduleMessage,
+  SCHEDULE_TOO_FAR_TEXT,
+} from '../../utils/scheduledMessages';
 import { useModalStyle } from '../../hooks/useModalStyle';
 import {
   toLocalDate,
@@ -121,7 +126,13 @@ export function ScheduleMessageModal({
       return;
     }
     const diffMs = sendAt.getTime() - Date.now();
-    if (diffMs < 60_000) {
+    // [Gitea #275] Say so as soon as a too-late time is picked, not on submit.
+    const tooFar = diffMs > MAX_SCHEDULE_AHEAD_MS;
+    setError((e) => {
+      if (tooFar) return SCHEDULE_TOO_FAR_TEXT;
+      return e === SCHEDULE_TOO_FAR_TEXT ? null : e;
+    });
+    if (diffMs < 60_000 || tooFar) {
       setPreview(null);
       return;
     }
@@ -149,6 +160,10 @@ export function ScheduleMessageModal({
       setError('Scheduled time must be at least 1 minute in the future.');
       return;
     }
+    if (diffMs > MAX_SCHEDULE_AHEAD_MS) {
+      setError(SCHEDULE_TOO_FAR_TEXT);
+      return;
+    }
     if (!messageText.trim()) {
       setError('Please enter a message to schedule.');
       return;
@@ -162,7 +177,7 @@ export function ScheduleMessageModal({
       onScheduled(delayId, sendAt.getTime(), content);
       onClose();
     } catch (err) {
-      setError(err instanceof Error ? err.message : 'Failed to schedule message.');
+      setError(describeScheduleError(err));
       setSubmitting(false);
     }
   };
@@ -247,6 +262,8 @@ export function ScheduleMessageModal({
                     <input
                       id="schedule-date"
                       type="date"
+                      min={toLocalDate(new Date())}
+                      max={toLocalDate(new Date(Date.now() + MAX_SCHEDULE_AHEAD_MS))}
                       value={dateValue}
                       onChange={(e) => setDateValue(e.target.value)}
                       style={pickerInputStyle(color, config)}
@@ -294,7 +311,8 @@ export function ScheduleMessageModal({
                   </Box>
                 </Box>
               ) : (
-                (dateValue || timeValue) && (
+                (dateValue || timeValue) &&
+                error !== SCHEDULE_TOO_FAR_TEXT && (
                   <Text size="T200" style={{ color: color.Critical.Main }}>
                     Must be at least 1 minute in the future
                   </Text>