fix: close 0.8.6 temporal and reliability gaps

Author: stefan-ernst

docs/temporal-semantics.md

@@ -0,0 +1,72 @@
+# Temporal semantics
+
+Windshift uses four distinct temporal types. Callers must identify which type
+they have before parsing, formatting, comparing, or persisting it.
+
+## Instants
+
+An instant identifies one point on the UTC timeline. API timestamps and Unix
+timestamps are instants.
+
+- Persist and exchange instants as UTC timestamps.
+- Authenticated surfaces display instants in the acting user's validated IANA
+  timezone.
+- If a stored user timezone is missing or invalid, display the instant in UTC.
+- Public surfaces without an acting user display instants in UTC unless the
+  surface explicitly owns another timezone.
+- Browser and server local timezones are never implicit presentation defaults.
+
+Frontend code formats instants through `formatInstant` or a formatter returned
+by `createTemporalFormatter`. Backend code uses `ResolveTimezoneOrUTC` only at
+boundaries where invalid stored user data must safely fall back.
+
+## Date-only values
+
+A date-only value is a Gregorian calendar label in `YYYY-MM-DD` form. Due
+dates, iteration dates, leave dates, and custom date fields are date-only unless
+their API explicitly says otherwise.
+
+- Do not convert date-only values through browser or user timezones.
+- Preserve the stored year, month, and day when formatting.
+- Do not infer a midnight instant from a date-only value except at a boundary
+  that explicitly converts a civil range to instants.
+
+Frontend code formats these values through `formatDateOnly`.
+
+## Schedule-local civil time
+
+A civil time combines calendar fields with an IANA timezone. Recurrences,
+on-call handoffs, and other schedules retain their own timezone even when the
+viewer uses a different timezone.
+
+- Validate schedule and request-supplied timezone names strictly.
+- Reject nonexistent or ambiguous wall-clock times unless that feature has a
+  documented DST policy.
+- Do not replace a schedule timezone with the user's display timezone.
+
+Backend code uses `ResolveTimezone`, `ParseCivilDate`, and the feature's civil
+clock resolver for these values.
+
+## Civil date ranges
+
+User-facing inclusive date ranges become half-open instant ranges before they
+reach timestamp queries:
+
+```text
+[start date at 00:00 local, day after end date at 00:00 local)
+```
+
+Convert both boundaries to UTC after constructing them in the relevant IANA
+timezone. Advance the exclusive boundary with calendar-day arithmetic, not a
+24-hour duration, so DST transition days remain correct. Backend code uses
+`CivilDateRangeUTC` for this conversion.
+
+## Durations
+
+A duration is elapsed time and has no timezone. Format and compare durations
+without calendar conversion. Labels such as "3 hours ago" compare instants but
+express the resulting duration.
+
+For worklogs, a duration submitted without explicit start and end clocks is
+anchored at the start of the submitted civil date in the resolved worklog
+timezone. Cookie, REST, and MCP entry points use this same deterministic rule.

frontend/src/lib/dialogs/ChannelConfigModal.svelte

@@ -21,6 +21,7 @@
   import ChannelSMTPConfig from '../features/channels/ChannelSMTPConfig.svelte';
   import ChannelFormConfig from '../features/channels/ChannelFormConfig.svelte';
   import FormBuilder from '../features/channels/FormBuilder.svelte';
+  import { formatAuthenticatedDateTime } from '../utils/authenticatedDateFormatter.js';
 
   let {
     isOpen = false,
@@ -681,7 +682,7 @@
           {#if channel.last_activity}
             <div class="pt-6 mt-6 border-t" style="border-color: var(--ds-border);">
               <div class="text-sm" style="color: var(--ds-text-subtle);">
-                {t('channel.lastActivity')}: {new Date(channel.last_activity).toLocaleString()}
+                {t('channel.lastActivity')}: {formatAuthenticatedDateTime(channel.last_activity)}
               </div>
             </div>
           {/if}

frontend/src/lib/dialogs/TestCaseViewModal.svelte

@@ -14,7 +14,7 @@
   import Modal from './Modal.svelte';
   import Button from '../components/Button.svelte';
   import { api } from '../api.js';
-  import { formatDateTimeLocale } from '../utils/dateFormatter.js';
+  import { formatAuthenticatedDateTime as formatDateTimeLocale } from '../utils/authenticatedDateFormatter.js';
   import { t } from '../stores/i18n.svelte.js';
 
   let {

frontend/src/lib/dialogs/TimeLogModal.svelte

@@ -13,7 +13,7 @@
   import Modal from './Modal.svelte';
   import DialogFooter from './DialogFooter.svelte';
   import { t } from '../stores/i18n.svelte.js';
-  import { formatDate } from '../utils/dateFormatter.js';
+  import { formatDate, worklogDateKey } from '../utils/dateFormatter.js';
 
   // Configuration props
   let {
@@ -57,7 +57,7 @@
     project_id: editingWorklog?.project_id ?? defaultProjectId,
     item_id: editingWorklog?.item_id ?? defaultItemId,
     description: editingWorklog?.description ?? '',
-    date: editingWorklog ? formatDate(new Date(editingWorklog.date * 1000)) : (defaultDate ?? formatDate(new Date())),
+    date: editingWorklog ? worklogDateKey(editingWorklog.date) : (defaultDate ?? formatDate(new Date())),
     start_time: editingWorklog ? formatTimeFromUnix(editingWorklog.start_time) : (defaultStartTime ?? ''),
     end_time: editingWorklog ? formatTimeFromUnix(editingWorklog.end_time) : '',
     duration: editingWorklog ? formatDurationFromMinutes(editingWorklog.duration_minutes) : ''

frontend/src/lib/dialogs/TimeProjectPermissionsModal.svelte

@@ -9,7 +9,7 @@
   import { api } from '../api.js';
   import { t } from '../stores/i18n.svelte.js';
   import { errorToast } from '../stores/toasts.svelte.js';
-  import { formatDateTimeLocale } from '../utils/dateFormatter.js';
+  import { formatAuthenticatedDateTime as formatDateTimeLocale } from '../utils/authenticatedDateFormatter.js';
   import { User, Users, X, Plus, Shield, UserCheck } from '@lucide/svelte';
   import DescriptionText from '../components/DescriptionText.svelte';
 
@@ -338,4 +338,3 @@
     </div>
   </div>
 </Modal>
-

frontend/src/lib/editors/InlineDateEditor.svelte

@@ -2,7 +2,7 @@
   import { tick } from 'svelte';
   import { Calendar } from '@lucide/svelte';
   import { t } from '../stores/i18n.svelte.js';
-  import { formatDate, formatDateShort } from '../utils/dateFormatter.js';
+  import { dateOnlyKey, formatDateOnly } from '../utils/dateFormatter.js';
   import BaseInlineEditor from './BaseInlineEditor.svelte';
   import Input from '../components/Input.svelte';
 
@@ -14,15 +14,15 @@
   } = $props();
 
   const effectivePlaceholder = $derived(placeholder || t('editors.selectDate'));
-  const displayValue = $derived(value ? (formatDateShort(value) || value) : '');
+  const displayValue = $derived(value ? (formatDateOnly(value) || value) : '');
 
   let baseEditor;
   let editValue = $state('');
   let inputElement = $state(null);
 
   function formatInputDate(dateStr) {
     if (!dateStr) return '';
-    try { return formatDate(new Date(dateStr)); } catch { return ''; }
+    return dateOnlyKey(dateStr);
   }
 
   function handleStartEdit() {

frontend/src/lib/features/actions/ActionLogs.svelte

@@ -6,6 +6,7 @@
   import Button from '../../components/Button.svelte';
   import ExecutionTraceModal from './ExecutionTraceModal.svelte';
   import { ArrowLeft, CheckCircle, XCircle, Clock, SkipForward, Eye } from '@lucide/svelte';
+  import { formatAuthenticatedDateTime } from '../../utils/authenticatedDateFormatter.js';
 
   let { workspaceId, action, onBack } = $props();
 
@@ -65,7 +66,7 @@
 
   function formatDate(dateStr) {
     if (!dateStr) return '-';
-    return new Date(dateStr).toLocaleString();
+    return formatAuthenticatedDateTime(dateStr);
   }
 </script>
 

frontend/src/lib/features/agents/AgentProfile.svelte

@@ -34,6 +34,7 @@
   import Tabs from '../../components/Tabs.svelte';
   import Textarea from '../../components/Textarea.svelte';
   import ConfirmDialog from '../../dialogs/ConfirmDialog.svelte';
+  import { formatAuthenticatedDateTime } from '../../utils/authenticatedDateFormatter.js';
   import AgentRunnerSetup from './AgentRunnerSetup.svelte';
 
   let { workspaceId, agentId, tab = 'overview' } = $props();
@@ -752,7 +753,7 @@
           </p>
           {#if agent.updated_at}
             <p class="mt-4 text-xs" style="color: var(--ds-text-subtlest);">
-              Updated {new Date(agent.updated_at).toLocaleString()}
+              Updated {formatAuthenticatedDateTime(agent.updated_at)}
             </p>
           {/if}
         </Card>

frontend/src/lib/features/analytics/analyticsView.js

@@ -1,3 +1,5 @@
+export { formatDateOnly } from '../../utils/dateFormatter.js';
+
 export const ANALYTICS_MAX_RANGE_DAYS = 366;
 export const ANALYTICS_DEFAULT_RANGE_DAYS = 84;
 
@@ -57,17 +59,6 @@ export function validateAnalyticsRange(startDate, endDate) {
   return null;
 }
 
-export function formatDateOnly(dateString, options = {}) {
-  const parts = dateParts(dateString);
-  if (!parts) return '—';
-  return new Intl.DateTimeFormat(undefined, {
-    month: 'short',
-    day: 'numeric',
-    timeZone: 'UTC',
-    ...options,
-  }).format(new Date(parts.timestamp));
-}
-
 export function formatDayNumber(value) {
   const number = Number(value) || 0;
   return new Intl.NumberFormat(undefined, {

frontend/src/lib/features/collections/BoardItemCard.svelte

@@ -3,7 +3,7 @@
   import Avatar from '../../components/Avatar.svelte';
   import DropIndicator from '../../layout/DropIndicator.svelte';
   import DropdownMenu from '../../layout/DropdownMenu.svelte';
-  import { formatDateShort } from '../../utils/dateFormatter.js';
+  import { formatDateOnly } from '../../utils/dateFormatter.js';
   import { itemTypeIconMap } from '../../utils/icons.js';
   import ItemKey from '../items/ItemKey.svelte';
   import CardFieldChip from './CardFieldChip.svelte';
@@ -159,7 +159,7 @@
             title="Due date"
           >
             <CalendarDays class="h-3 w-3 shrink-0" />
-            {formatDateShort(item.due_date)}
+            {formatDateOnly(item.due_date)}
           </span>
         {/if}
         <DependencySummary {item} links={dependencyLinks} />