feat: show model in working indicator and fix streaming bottom jitter

- Working indicator shows provider icon and model name with the live
  status (e.g. 'Fable 5 is reading file'), localized via
  chat.statusRow.modelStatus
- Pin auto-follow to the exact fractional scroll maximum and re-pin on
  every passive follow instead of skipping within tolerance
- Round message text line-height to whole pixels so streamed content
  grows on the pixel grid; kills the 1px vertical jitter of
  bottom-anchored rows during streaming

packages/ui/src/components/chat/StatusRow.tsx

@@ -133,6 +133,8 @@ interface StatusRowProps {
   showAssistantStatus?: boolean;
   showTodos?: boolean;
   agentName?: string;
+  modelName?: string | null;
+  providerId?: string | null;
   leftAccessory?: React.ReactNode;
 }
 
@@ -150,6 +152,8 @@ export const StatusRow: React.FC<StatusRowProps> = ({
   showAssistantStatus = true,
   showTodos = true,
   agentName,
+  modelName,
+  providerId,
   leftAccessory,
 }) => {
   const { t } = useI18n();
@@ -313,6 +317,8 @@ export const StatusRow: React.FC<StatusRowProps> = ({
               isWaitingForPermission={isWaitingForPermission}
               retryInfo={retryInfo}
               agentName={agentName}
+              modelName={modelName}
+              providerId={providerId}
             />
           ) : leftAccessory ? (
             leftAccessory

packages/ui/src/components/chat/StatusRowContainer.tsx

@@ -3,6 +3,7 @@ import React from 'react';
 import { useAssistantStatus } from '@/hooks/useAssistantStatus';
 import { useConfigStore } from '@/stores/useConfigStore';
 import { useSessionUIStore } from '@/sync/session-ui-store';
+import { getProviderModelDisplayName } from '@/lib/modelDisplay';
 import { StatusRow } from './StatusRow';
 
 /**
@@ -22,6 +23,19 @@ export const StatusRowContainer: React.FC = React.memo(() => {
     );
     const { working } = useAssistantStatus();
     const currentAgentName = useConfigStore((state) => state.currentAgentName);
+    const currentProviderId = useConfigStore((state) => state.currentProviderId);
+    const currentModelId = useConfigStore((state) => state.currentModelId);
+    const providers = useConfigStore((state) => state.providers);
+
+    const modelDisplayName = React.useMemo(() => {
+        if (!currentModelId) {
+            return null;
+        }
+        const provider = currentProviderId && providers.length > 0
+            ? providers.find((candidate) => candidate.id === currentProviderId)
+            : undefined;
+        return getProviderModelDisplayName(provider, currentModelId) || null;
+    }, [currentProviderId, currentModelId, providers]);
 
     const wasAborted = Boolean(abortRecord && !abortRecord.acknowledged);
 
@@ -37,6 +51,8 @@ export const StatusRowContainer: React.FC = React.memo(() => {
             showAssistantStatus
             showTodos={false}
             agentName={currentAgentName}
+            modelName={modelDisplayName}
+            providerId={currentProviderId ?? null}
         />
     );
 });

packages/ui/src/components/chat/message/parts/WorkingPlaceholder.tsx

@@ -1,5 +1,8 @@
 import React from 'react';
 import { BusyDots } from './BusyDots';
+import { useI18n } from '@/lib/i18n';
+import { useProviderLogo } from '@/hooks/useProviderLogo';
+import { useThemeSystem } from '@/contexts/useThemeSystem';
 
 interface WorkingPlaceholderProps {
   isWorking: boolean;
@@ -8,6 +11,8 @@ interface WorkingPlaceholderProps {
   isWaitingForPermission?: boolean;
   retryInfo?: { attempt?: number; next?: number } | null;
   agentName?: string;
+  modelName?: string | null;
+  providerId?: string | null;
 }
 
 const STATUS_DISPLAY_TIME_MS = 1200;
@@ -58,7 +63,13 @@ export function WorkingPlaceholder({
   isGenericStatus,
   isWaitingForPermission,
   retryInfo,
+  modelName,
+  providerId,
 }: WorkingPlaceholderProps) {
+  const { t } = useI18n();
+  const { src: providerLogoSrc, onError: handleProviderLogoError, hasLogo: hasProviderLogo } = useProviderLogo(providerId ?? null);
+  const { currentTheme } = useThemeSystem();
+  const isDarkTheme = currentTheme?.metadata.variant === 'dark';
   const [displayedText, setDisplayedText] = React.useState<string | null>(null);
   const [displayedPermission, setDisplayedPermission] = React.useState<boolean>(false);
   const displayedTextRef = React.useRef(displayedText);
@@ -211,7 +222,10 @@ export function WorkingPlaceholder({
     return null;
   }
 
-  const label = displayedText.charAt(0).toUpperCase() + displayedText.slice(1);
+  const trimmedModelName = typeof modelName === 'string' ? modelName.trim() : '';
+  const label = trimmedModelName.length > 0
+    ? t('chat.statusRow.modelStatus', { model: trimmedModelName, status: displayedText })
+    : displayedText.charAt(0).toUpperCase() + displayedText.slice(1);
 
   return (
     <div
@@ -224,6 +238,18 @@ export function WorkingPlaceholder({
       data-waiting={displayedPermission ? 'true' : undefined}
     >
       <span className="typography-ui-header">
+        {hasProviderLogo && providerLogoSrc ? (
+          <img
+            src={providerLogoSrc}
+            alt=""
+            aria-hidden="true"
+            className="inline-block h-3.5 w-3.5 mr-1.5 align-[-2px]"
+            style={{
+              filter: isDarkTheme ? 'brightness(0.9) contrast(1.1) invert(1)' : 'brightness(0.9) contrast(1.1)',
+            }}
+            onError={handleProviderLogoError}
+          />
+        ) : null}
         {label}
         <BusyDots />
       </span>

packages/ui/src/hooks/useChatAutoFollow.ts

@@ -346,13 +346,19 @@ export const useChatAutoFollow = ({
         const el = scrollRef.current;
         if (!el) return;
         markAuto(el);
+        // `scrollHeight` is rounded to an integer while the real content height
+        // is fractional (prose line-heights), so `scrollTop = scrollHeight`
+        // leaves a 0–1px remainder that oscillates per streamed token and makes
+        // bottom-anchored rows jitter vertically. An over-large target clamps to
+        // the exact fractional maximum instead, pinning content to the bottom.
+        const overshootTarget = el.scrollHeight + 4096;
         if (behavior === 'smooth') {
-            el.scrollTo({ top: el.scrollHeight, behavior });
+            el.scrollTo({ top: overshootTarget, behavior });
             return;
         }
         // Direct `scrollTop` assignment bypasses any CSS `scroll-behavior: smooth`
         // and lands in the same frame — no visible catch-up animation.
-        el.scrollTop = el.scrollHeight;
+        el.scrollTop = overshootTarget;
     }, [markAuto]);
 
     // `force` true = user-intent jump (clears released and always scrolls).
@@ -370,15 +376,14 @@ export const useChatAutoFollow = ({
         if (!el) return;
         if (!force && stateRef.current !== 'following') return;
 
-        const distance = distanceFromBottom(el);
+        // Always re-pin, even when already within tolerance of the bottom.
-        if (distance < AUTO_MATCH_TOLERANCE_PX) {
+        // Sub-tolerance growth (fractional line-height remainders) would
-            // Already at the bottom; just refresh the auto marker so the next
+        // otherwise leave the bottom drifting by up to ±AUTO_MATCH_TOLERANCE_PX
-            // scroll event is recognised as ours.
+        // between full re-pins, which reads as 1px vertical jitter on
-            markAuto(el);
+        // bottom-anchored rows during streaming. The write happens pre-paint
-            return;
+        // (ResizeObserver) and is a no-op when the position is unchanged.
-        }
         scrollToBottomNow(force ? behavior : 'auto');
-    }, [isActive, markAuto, scrollToBottomNow, setStateValue]);
+    }, [isActive, scrollToBottomNow, setStateValue]);
 
     // User left the bottom — release auto-follow.
     const stop = React.useCallback(() => {

packages/ui/src/index.css

@@ -138,6 +138,16 @@ textarea[data-chat-input="true"]:focus-visible {
   cursor: not-allowed;
 }
 
+/* Fractional line heights (1.625 × font-size) make streamed content grow by
+   sub-pixel amounts while scroll positions quantize to the device-pixel grid.
+   The residue accumulates and bottom-anchored rows (status indicator) creep
+   and snap by 1px per few lines during streaming. Rounding the line height to
+   whole pixels keeps content growth on the pixel grid. */
+.message-content-text.leading-relaxed,
+.message-content-text .leading-relaxed {
+  line-height: round(1.625em, 1px);
+}
+
 :root.light .message-content-text::selection,
 :root.light .message-content-text ::selection {
   background: color-mix(in srgb, var(--interactive-border-focus) 18%, transparent);

packages/ui/src/lib/i18n/messages/en.ts

@@ -1797,6 +1797,7 @@ export const dict = {
   'chat.statusRow.todo.priority.low': 'Low priority',
   'chat.statusRow.actions.stopGeneratingAria': 'Stop generating',
   'chat.statusRow.tasksTitle': 'Tasks',
+  'chat.statusRow.modelStatus': '{model} is {status}',
   'chat.statusRow.summary.activeLeft': '{active} active · {left} left',
   'chat.statusRow.aborted': 'Aborted',
   'chat.revertIndicator.redo': 'Redo',

packages/ui/src/lib/i18n/messages/es.ts

@@ -1775,6 +1775,7 @@ export const dict: Record<I18nKey, string> = {
   "chat.statusRow.todo.priority.low": "Prioridad baja",
   "chat.statusRow.actions.stopGeneratingAria": "Detener la generación",
   "chat.statusRow.tasksTitle": "Tareas",
+  "chat.statusRow.modelStatus": "{model} · {status}",
   "chat.statusRow.summary.activeLeft": "{active} activas · {left} restantes",
   "chat.statusRow.aborted": "Interrumpido",
   "chat.revertIndicator.redo": "Rehacer",

packages/ui/src/lib/i18n/messages/fr.ts

@@ -1601,6 +1601,7 @@ export const dict = {
   'chat.statusRow.todo.priority.low': 'Faible priorité',
   'chat.statusRow.actions.stopGeneratingAria': 'Arrêter de générer',
   'chat.statusRow.tasksTitle': 'Tâches',
+  'chat.statusRow.modelStatus': '{model} · {status}',
   'chat.statusRow.summary.activeLeft': '{active} actif · {left} gauche',
   'chat.statusRow.aborted': 'Avorté',
   'chat.revertIndicator.redo': 'Refaire',

packages/ui/src/lib/i18n/messages/ja.ts

@@ -1793,6 +1793,7 @@ export const dict: Record<I18nKey, string> = {
   'chat.statusRow.todo.priority.low': '低優先度',
   'chat.statusRow.actions.stopGeneratingAria': '生成を停止',
   'chat.statusRow.tasksTitle': 'タスク',
+  'chat.statusRow.modelStatus': '{model} · {status}',
   'chat.statusRow.summary.activeLeft': '{active}アクティブ · {left}残り',
   'chat.statusRow.aborted': '中止されました',
   'chat.revertIndicator.redo': 'やり直し',

packages/ui/src/lib/i18n/messages/ko.ts

@@ -1799,6 +1799,7 @@ export const dict: Record<I18nKey, string> = {
   'chat.statusRow.todo.priority.low': '낮은 우선순위',
   'chat.statusRow.actions.stopGeneratingAria': '생성 중지',
   'chat.statusRow.tasksTitle': '작업',
+  'chat.statusRow.modelStatus': '{model} · {status}',
   'chat.statusRow.summary.activeLeft': '{active}개 활성 · {left}개 남음',
   'chat.statusRow.aborted': '중단됨',
   'chat.revertIndicator.redo': '다시 실행',

packages/ui/src/lib/i18n/messages/pl.ts

@@ -687,6 +687,7 @@ export const dict: Record<I18nKey, string> = {
   'chat.statusRow.todo.priority.low': 'Niski priorytet',
   'chat.statusRow.actions.stopGeneratingAria': 'Zatrzymaj generowanie',
   'chat.statusRow.tasksTitle': 'Zadania',
+  'chat.statusRow.modelStatus': '{model} · {status}',
   'chat.statusRow.summary.activeLeft': '{active} aktywne · {left} pozostało',
   'chat.statusRow.aborted': 'Przerwane',
   'chat.revertIndicator.redo': 'Ponów',

packages/ui/src/lib/i18n/messages/pt-BR.ts

@@ -1775,6 +1775,7 @@ export const dict: Record<I18nKey, string> = {
   "chat.statusRow.todo.priority.low": "Prioridade baixa",
   "chat.statusRow.actions.stopGeneratingAria": "Parar a geração",
   "chat.statusRow.tasksTitle": "Tarefas",
+  "chat.statusRow.modelStatus": "{model} · {status}",
   "chat.statusRow.summary.activeLeft": "{active} ativas · {left} restantes",
   "chat.statusRow.aborted": "Interrompido",
   "chat.revertIndicator.redo": "Refazer",

packages/ui/src/lib/i18n/messages/uk.ts

@@ -1775,6 +1775,7 @@ export const dict: Record<I18nKey, string> = {
   "chat.statusRow.todo.priority.low": "Низький пріоритет",
   "chat.statusRow.actions.stopGeneratingAria": "Припинити генерацію",
   "chat.statusRow.tasksTitle": "завдання",
+  "chat.statusRow.modelStatus": "{model} · {status}",
   "chat.statusRow.summary.activeLeft": "Активних: {active} · залишилось: {left}",
   "chat.statusRow.aborted": "Перервано",
   "chat.revertIndicator.redo": "Повторити",

packages/ui/src/lib/i18n/messages/zh-CN.ts

@@ -1763,6 +1763,7 @@ export const dict: Record<I18nKey, string> = {
   'chat.statusRow.todo.priority.low': '低优先级',
   'chat.statusRow.actions.stopGeneratingAria': '停止生成',
   'chat.statusRow.tasksTitle': '任务',
+  'chat.statusRow.modelStatus': '{model} · {status}',
   'chat.statusRow.summary.activeLeft': '{active} 个活跃 · 剩余 {left} 个',
   'chat.statusRow.aborted': '已中止',
   'chat.revertIndicator.redo': '重做',

packages/ui/src/lib/i18n/messages/zh-TW.ts

@@ -1767,6 +1767,7 @@ export const dict: Record<I18nKey, string> = {
   'chat.statusRow.todo.priority.low': '低優先級',
   'chat.statusRow.actions.stopGeneratingAria': '停止生成',
   'chat.statusRow.tasksTitle': '任務',
+  'chat.statusRow.modelStatus': '{model} · {status}',
   'chat.statusRow.summary.activeLeft': '{active} 個活躍 · 剩餘 {left} 個',
   'chat.statusRow.aborted': '已中止',
   'chat.revertIndicator.redo': '重做',