refactor: centralise user timezone as a standalone setting

Browser timezone is now synced to user_settings["user_timezone"] on
every login/page load (App.vue). The briefing scheduler and LLM context
both read from this single source, falling back to the legacy
briefing_config.timezone for existing users during migration.

- App.vue: PUT /api/settings with browser IANA timezone on startAppServices
- routes/chat.py: fall back to stored user_timezone when not sent in request
- briefing_scheduler: read user_timezone setting; briefing_config.timezone
  kept as fallback only
- routes/briefing.py: pass tz_override from user_timezone to live-patched scheduler
- Remove timezone field from BriefingConfig interface and all briefing UI

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

frontend/src/App.vue

@@ -8,7 +8,7 @@ import { useShortcuts } from "@/composables/useShortcuts";
 import { useAuthStore } from "@/stores/auth";
 import { useChatStore } from "@/stores/chat";
 import { useSettingsStore } from "@/stores/settings";
-import { apiGet } from "@/api/client";
+import { apiGet, apiPut } from "@/api/client";
 
 useTheme();
 
@@ -22,6 +22,8 @@ const { showShortcuts, toggleShortcuts, closeShortcuts } = useShortcuts();
 function startAppServices() {
   chatStore.startStatusPolling();
   settingsStore.fetchSettings();
+  // Sync browser timezone to the server on every login/page load.
+  apiPut("/api/settings", { user_timezone: Intl.DateTimeFormat().resolvedOptions().timeZone }).catch(() => {});
 }
 
 function stopAppServices() {

frontend/src/api/client.ts

@@ -329,7 +329,6 @@ export interface BriefingConfig {
   slots: BriefingSlots;
   notifications: boolean;
   temp_unit: 'C' | 'F';
-  timezone: string;
 }
 
 export interface BriefingFeed {
@@ -364,7 +363,6 @@ const DEFAULT_BRIEFING_CONFIG: BriefingConfig = {
   slots: { compilation: true, morning: true, midday: false, afternoon: false },
   notifications: true,
   temp_unit: 'C',
-  timezone: '',
 };
 
 export async function getBriefingConfig(): Promise<BriefingConfig> {

frontend/src/components/BriefingSetupWizard.vue

@@ -20,7 +20,6 @@ const config = reactive<BriefingConfig>({
   slots: { compilation: true, morning: true, midday: false, afternoon: false },
   notifications: true,
   temp_unit: 'C',
-  timezone: '',
 })
 
 // Step 2 — locations

frontend/src/views/SettingsView.vue

@@ -258,7 +258,6 @@ const briefingConfig = ref<BriefingConfig>({
   slots: { compilation: true, morning: true, midday: false, afternoon: false },
   notifications: true,
   temp_unit: 'C',
-  timezone: '',
 });
 const briefingFeeds = ref<BriefingFeed[]>([]);
 const briefingSaving = ref(false);
@@ -284,10 +283,6 @@ function _parseTopics(raw: unknown): string[] {
 async function loadBriefingTab() {
   briefingConfig.value = await getBriefingConfig();
   briefingFeeds.value = await getBriefingFeeds();
-  // Auto-populate timezone from browser if not already stored.
-  if (!briefingConfig.value.timezone) {
-    briefingConfig.value.timezone = Intl.DateTimeFormat().resolvedOptions().timeZone;
-  }
   const allSettings = await apiGet<Record<string, string>>('/api/settings').catch(() => ({} as Record<string, string>));
   briefingIncludeTopics.value = _parseTopics(allSettings['briefing_include_topics'] ?? '[]');
   briefingExcludeTopics.value = _parseTopics(allSettings['briefing_exclude_topics'] ?? '[]');
@@ -1694,35 +1689,6 @@ function formatUserDate(iso: string): string {
         </div>
       </section>
 
-      <!-- Timezone -->
-      <section class="settings-section full-width">
-        <h2>Timezone</h2>
-        <p class="section-desc">
-          Briefing slots fire at the times below in this timezone.
-          Auto-detected from your browser — override if the server should use a different zone.
-        </p>
-        <div class="briefing-timezone-row">
-          <input
-            type="text"
-            class="input"
-            v-model="briefingConfig.timezone"
-            placeholder="e.g. America/New_York"
-            style="flex: 1"
-          />
-          <button
-            type="button"
-            class="btn-secondary"
-            @click="briefingConfig.timezone = Intl.DateTimeFormat().resolvedOptions().timeZone"
-          >Detect</button>
-        </div>
-        <p class="field-hint">
-          Use an
-          <a href="https://en.wikipedia.org/wiki/List_of_tz_database_time_zones" target="_blank" rel="noopener">IANA timezone name</a>
-          (e.g. <code>Europe/London</code>, <code>America/Chicago</code>).
-          Your browser reports: <strong>{{ Intl.DateTimeFormat().resolvedOptions().timeZone }}</strong>
-        </p>
-      </section>
-
       <!-- Slots -->
       <section class="settings-section full-width">
         <h2>Scheduled Slots</h2>
@@ -1747,8 +1713,8 @@ function formatUserDate(iso: string): string {
             </label>
           </div>
         </div>
-        <p v-if="briefingConfig.timezone" class="field-hint" style="margin-top: 0.5rem">
+        <p class="field-hint" style="margin-top: 0.5rem">
-          Firing in timezone: <strong>{{ briefingConfig.timezone }}</strong>
+          Firing in timezone: <strong>{{ Intl.DateTimeFormat().resolvedOptions().timeZone }}</strong>
         </p>
       </section>
 
@@ -3313,12 +3279,6 @@ FABLE_API_KEY=&lt;your-api-key&gt;</pre>
   flex-wrap: wrap;
   margin-top: 0.5rem;
 }
-.briefing-timezone-row {
-  display: flex;
-  gap: 0.5rem;
-  align-items: center;
-  margin-bottom: 0.5rem;
-}
 .briefing-unit-toggle {
   display: flex;
   gap: 0;

src/fabledassistant/routes/briefing.py

@@ -44,9 +44,10 @@ async def get_config():
 async def put_config():
     data = await request.get_json()
     await set_settings_batch(g.user.id, {"briefing_config": json.dumps(data)})
-    # Live-patch the scheduler so the new timezone takes effect immediately.
+    # Live-patch the scheduler using the stored user_timezone.
     from fabledassistant.services.briefing_scheduler import update_user_schedule
-    update_user_schedule(g.user.id, data)
+    tz_override = await get_setting(g.user.id, "user_timezone") or None
+    update_user_schedule(g.user.id, data, tz_override=tz_override)
     return jsonify({"ok": True})
 
 

src/fabledassistant/routes/chat.py

@@ -149,6 +149,8 @@ async def send_message_route(conv_id: int):
     rag_project_id = data.get("rag_project_id") or None
     workspace_project_id = data.get("workspace_project_id") or None
     user_timezone = data.get("user_timezone") or None
+    if not user_timezone:
+        user_timezone = await get_setting(uid, "user_timezone") or None
     effective_rag_project_id = workspace_project_id or rag_project_id
 
     # Reject if generation already running for this conversation

src/fabledassistant/services/briefing_scheduler.py

@@ -56,17 +56,22 @@ async def _get_briefing_enabled_users() -> list[tuple[int, str]]:
     import json
     async with async_session() as session:
         result = await session.execute(
-            select(Setting).where(Setting.key == "briefing_config")
+            select(Setting).where(Setting.key.in_(["briefing_config", "user_timezone"]))
         )
         rows = list(result.scalars().all())
 
-    enabled = []
+    by_user: dict[int, dict[str, str]] = {}
     for row in rows:
+        by_user.setdefault(row.user_id, {})[row.key] = row.value or ""
+
+    enabled = []
+    for user_id, settings in by_user.items():
         try:
-            config = json.loads(row.value) if row.value else {}
+            config = json.loads(settings.get("briefing_config", "{}") or "{}")
             if config.get("enabled"):
-                tz = _resolve_timezone(config.get("timezone", "UTC"))
+                tz_str = settings.get("user_timezone") or config.get("timezone", "UTC")
-                enabled.append((row.user_id, tz))
+                tz = _resolve_timezone(tz_str)
+                enabled.append((user_id, tz))
         except Exception:
             pass
     return enabled
@@ -105,13 +110,15 @@ def _remove_user_jobs(user_id: int) -> None:
 
 # ── Public API ────────────────────────────────────────────────────────────────
 
-def update_user_schedule(user_id: int, config: dict) -> None:
+def update_user_schedule(user_id: int, config: dict, tz_override: str | None = None) -> None:
     """
     Called when a user saves their briefing config via the settings UI.
     Live-patches the scheduler — no restart required.
+    tz_override takes priority over any timezone in config.
     """
     if config.get("enabled"):
-        tz = _resolve_timezone(config.get("timezone", "UTC"))
+        tz_str = tz_override or config.get("timezone", "UTC")
+        tz = _resolve_timezone(tz_str)
         _add_user_jobs(user_id, tz)
     else:
         _remove_user_jobs(user_id)