diff --git a/frontend/src/features/agents/CustomAgentChatView.test.tsx b/frontend/src/features/agents/CustomAgentChatView.test.tsx
index dfbea426..45f84f31 100644
--- a/frontend/src/features/agents/CustomAgentChatView.test.tsx
+++ b/frontend/src/features/agents/CustomAgentChatView.test.tsx
@@ -383,6 +383,7 @@ describe("CustomAgentChatView", () => {
 
       expect(agentBubble).toBeTruthy();
       expect(errorBubble).toBeTruthy();
+      expect(within(errorBubble!).getByText("Session Codex")).toBeTruthy();
       expect(
         within(agentBubble!).getByText(expectedChatTime(firstDeltaReceivedAtMs)),
       ).toBeTruthy();
diff --git a/frontend/src/features/agents/CustomAgentChatView.tsx b/frontend/src/features/agents/CustomAgentChatView.tsx
index 78aa665b..c2905929 100644
--- a/frontend/src/features/agents/CustomAgentChatView.tsx
+++ b/frontend/src/features/agents/CustomAgentChatView.tsx
@@ -144,6 +144,23 @@ function describeOpenFailure(e: unknown): string {
   return message || "Cause technique non disponible.";
 }
 
+function structuredSessionLabel(
+  adapter: AgentProfile["structuredAdapter"],
+): string | null {
+  switch (adapter) {
+    case "codex":
+      return "Session Codex";
+    case "claude":
+      return "Session Claude";
+    case "openCode":
+      return "Session OpenCode";
+    case "openAiCompatible":
+      return "Session HTTP";
+    default:
+      return null;
+  }
+}
+
 function instrumentationError(e: unknown): Record<string, unknown> {
   if (e && typeof e === "object") {
     const err = e as GatewayError & { name?: string };
@@ -1018,6 +1035,7 @@ export function CustomAgentChatView({
     [agentId, conversationId, projectId],
   );
   const displayTurns = turns;
+  const sessionLabel = structuredSessionLabel(profile.structuredAdapter);
   const [requesterDelegation, setRequesterDelegation] =
     useState<RequesterDelegationState>({ active: false });
 
@@ -2162,6 +2180,7 @@ export function CustomAgentChatView({
               key={index}
               turn={turn}
               requesterName={agentName}
+              sessionLabel={sessionLabel}
               expandedProgressKeys={expandedProgressKeys}
               onToggleProgressExpanded={(key) =>
                 setExpandedProgressKeys((prev) => {
@@ -2352,11 +2371,13 @@ export function CustomAgentChatView({
 function ChatBubble({
   turn,
   requesterName,
+  sessionLabel,
   expandedProgressKeys,
   onToggleProgressExpanded,
 }: {
   turn: ChatTurn;
   requesterName: string;
+  sessionLabel: string | null;
   expandedProgressKeys: Set<string>;
   onToggleProgressExpanded: (key: string) => void;
 }) {
@@ -2406,6 +2427,9 @@ function ChatBubble({
               labelClassName="font-semibold text-danger"
             />
           )}
+          {turn.role === "error" && sessionLabel && (
+            <p className="mb-1 font-medium text-danger/85">{sessionLabel}</p>
+          )}
           {turn.role === "unknown" ? "Chunk inconnu reçu: " : ""}
           <span className="whitespace-pre-wrap break-words">{turn.text}</span>
         </div>