diff --git a/frontend/src/components/agents/AgentChatPanel.tsx b/frontend/src/components/agents/AgentChatPanel.tsx
index c1f2fc4b19..d9b90c6a4b 100644
--- a/frontend/src/components/agents/AgentChatPanel.tsx
+++ b/frontend/src/components/agents/AgentChatPanel.tsx
@@ -185,6 +185,8 @@ type Props = {
     /** Progression live pendant l’envoi (SSE). */
     liveSteps?: AgentChatStep[];
     liveAssistantText?: string | null;
+    /** Provider actif actuel (pour filtrer les erreurs non pertinentes) */
+    activeRoutingProvider?: string | null;
 };
 
 export function AgentChatPanel({
@@ -212,6 +214,7 @@ export function AgentChatPanel({
     activeSubagentCount = 0,
     liveSteps = [],
     liveAssistantText = null,
+    activeRoutingProvider = null,
 }: Props) {
     const scrollRef = useRef<HTMLDivElement>(null);
     const textareaRef = useRef<HTMLTextAreaElement>(null);
@@ -308,7 +311,7 @@ export function AgentChatPanel({
                 </div>
             )}
 
-            <AgentErrorAlert agent={agent} compact />
+            <AgentErrorAlert agent={agent} compact activeProvider={activeRoutingProvider} />
 
             {activeSubagentCount > 0 && (
                 <div class="shrink-0 border-b border-info/30 bg-info/10 px-3 py-2 text-xs text-info sm:px-4">
@@ -515,7 +518,7 @@ export function AgentChatPanel({
                 </div>
             )}
 
-            <div class="shrink-0 bg-base-100 p-3 pb-[max(0.75rem,env(safe-area-inset-bottom))] sm:p-4">
+            <div class="agent-chat-composer shrink-0 bg-base-100 p-3 pb-[max(0.75rem,env(safe-area-inset-bottom))] sm:p-4">
                 {error && (
                     <p class="mb-2 rounded-lg border border-error/30 bg-error/10 px-3 py-2 text-xs text-error" role="alert">
                         {error}
diff --git a/frontend/src/components/agents/AgentChatView.tsx b/frontend/src/components/agents/AgentChatView.tsx
index 0a3c9ab481..3a787db891 100644
--- a/frontend/src/components/agents/AgentChatView.tsx
+++ b/frontend/src/components/agents/AgentChatView.tsx
@@ -175,13 +175,15 @@ export function AgentChatView({ agent, onBack, onAgentUpdated, userName }: Props
                 </div>
             )}
 
-            <AgentViewSwitcher
-                mode={viewMode}
-                runsActive={runsActive}
-                runsCount={runsCount}
-                sessionsCount={sessionsCount}
-                onChange={(mode) => switchView(mode, focusedRunUuid ?? agent.latest_run?.uuid ?? null)}
-            />
+            <div class="hidden sm:block">
+                <AgentViewSwitcher
+                    mode={viewMode}
+                    runsActive={runsActive}
+                    runsCount={runsCount}
+                    sessionsCount={sessionsCount}
+                    onChange={(mode) => switchView(mode, focusedRunUuid ?? agent.latest_run?.uuid ?? null)}
+                />
+            </div>
 
             <div class="flex min-h-0 min-w-0 flex-1">
                 {viewMode === 'runs' ? (
diff --git a/frontend/src/components/agents/AgentConversationView.tsx b/frontend/src/components/agents/AgentConversationView.tsx
index f39e08936e..dd05fcd174 100644
--- a/frontend/src/components/agents/AgentConversationView.tsx
+++ b/frontend/src/components/agents/AgentConversationView.tsx
@@ -369,7 +369,7 @@ export function AgentConversationView({
 
     return (
         <div class="flex min-h-0 min-w-0 flex-1 flex-col lg:flex-row">
-            <aside class="flex max-h-[min(30vh,14rem)] min-h-0 shrink-0 flex-col border-b border-base-300 bg-base-200/20 lg:max-h-none lg:w-72 lg:max-w-[40%] lg:border-b-0 lg:border-e">
+            <aside class="hidden shrink-0 flex-col border-e border-base-300 bg-base-200/20 lg:flex lg:w-72 lg:max-w-[40%]">
                 <div class="flex shrink-0 items-center justify-end gap-1 px-3 pt-3">
                     <button
                         class="btn btn-ghost btn-sm btn-square size-9 min-h-9 p-0"
@@ -447,6 +447,7 @@ export function AgentConversationView({
                         activeSubagentCount={activeSubagentCount}
                         liveSteps={liveSteps}
                         liveAssistantText={liveAssistantText}
+                        activeRoutingProvider={agent.provider?.provider ?? null}
                     />
             </div>
         </div>
diff --git a/frontend/src/components/agents/AgentErrorAlert.tsx b/frontend/src/components/agents/AgentErrorAlert.tsx
index f54e5139a1..9213d0fb1a 100644
--- a/frontend/src/components/agents/AgentErrorAlert.tsx
+++ b/frontend/src/components/agents/AgentErrorAlert.tsx
@@ -1,4 +1,5 @@
-import { AlertCircle } from 'lucide-preact';
+import { AlertCircle, X } from 'lucide-preact';
+import { useState } from 'preact/hooks';
 import type { Agent } from '../../lib/domain-api';
 import { getAgentErrorMessage } from '../../lib/agent-errors';
 import { agentDetailPath } from '../../lib/agent-routes';
@@ -8,12 +9,46 @@ type Props = {
     agent: Agent;
     compact?: boolean;
     onNavigate?: (event: MouseEvent, path: string) => void;
+    /** Provider actuellement actif (si différent du default agent) */
+    activeProvider?: string | null;
 };
 
-export function AgentErrorAlert({ agent, compact = false, onNavigate }: Props) {
+/**
+ * Détermine si l'erreur est pertinente pour le contexte actuel.
+ * Une erreur Ollama n'est pas pertinente si l'agent tourne actuellement sur Gemini.
+ */
+function isErrorRelevant(
+    agent: Agent,
+    activeProvider: string | null | undefined,
+): boolean {
+    const errorMessage = getAgentErrorMessage(agent);
+    if (!errorMessage) {
+        return false;
+    }
+
+    // Si pas de provider actif spécifié, on montre l'erreur
+    if (!activeProvider) {
+        return true;
+    }
+
+    const lower = errorMessage.toLowerCase();
+    const isOllamaError = lower.includes('ollama');
+    const isGeminiActive = activeProvider === 'gemini' || agent.provider?.provider === 'gemini';
+
+    // Si l'erreur est Ollama mais que l'agent tourne sur Gemini, on cache l'erreur
+    if (isOllamaError && isGeminiActive) {
+        return false;
+    }
+
+    return true;
+}
+
+export function AgentErrorAlert({ agent, compact = false, onNavigate, activeProvider }: Props) {
+    const [dismissed, setDismissed] = useState(false);
+
     const message = getAgentErrorMessage(agent);
 
-    if (!message) {
+    if (!message || dismissed || !isErrorRelevant(agent, activeProvider)) {
         return null;
     }
 
@@ -26,13 +61,13 @@ export function AgentErrorAlert({ agent, compact = false, onNavigate }: Props) {
 
     return (
         <div
-            class={`rounded-lg border border-error/30 bg-error/10 text-error ${compact ? 'px-3 py-2' : 'p-3'}`}
+            class={`shrink-0 rounded-lg border border-error/30 bg-error/10 text-error ${compact ? 'px-3 py-2' : 'p-3'}`}
             role="alert"
         >
             <div class="flex items-start gap-2">
                 <AlertCircle class={`mt-0.5 shrink-0 ${compact ? 'size-3.5' : 'size-4'}`} aria-hidden />
                 <div class="min-w-0 flex-1">
-                    <p class={`font-medium ${compact ? 'text-[11px]' : 'text-xs'}`}>Dernière erreur</p>
+                    <p class={`font-medium ${compact ? 'text-[11px]' : 'text-xs'}`}>Erreur récente</p>
                     <p class={`mt-0.5 break-words text-error/90 ${compact ? 'line-clamp-3 text-[11px]' : 'text-xs'}`}>
                         {message}
                     </p>
@@ -46,6 +81,14 @@ export function AgentErrorAlert({ agent, compact = false, onNavigate }: Props) {
                         </a>
                     )}
                 </div>
+                <button
+                    type="button"
+                    class="btn btn-ghost btn-xs size-6 min-h-6 shrink-0 rounded-md p-0 text-error/70 hover:bg-error/20 hover:text-error"
+                    aria-label="Masquer l'erreur"
+                    onClick={() => setDismissed(true)}
+                >
+                    <X class="size-3.5" aria-hidden />
+                </button>
             </div>
         </div>
     );
diff --git a/frontend/src/styles/global.css b/frontend/src/styles/global.css
index 67391e08a9..664c90dcfb 100644
--- a/frontend/src/styles/global.css
+++ b/frontend/src/styles/global.css
@@ -658,3 +658,18 @@ input {
     color: var(--color-error);
     font-weight: 600;
 }
+
+/* Mobile chat improvements: composer always accessible, full-width messages */
+@media (max-width: 640px) {
+    /* Agent chat composer: safe bottom spacing */
+    .agent-chat-composer {
+        padding-bottom: max(0.75rem, env(safe-area-inset-bottom));
+    }
+
+    /* Prevent horizontal overflow on messages */
+    .agent-chat-message {
+        max-width: 100%;
+        word-wrap: break-word;
+        overflow-wrap: break-word;
+    }
+}