diff --git a/packages/ui/src/components/chat/ModelControls.tsx b/packages/ui/src/components/chat/ModelControls.tsx
index 4fc705cb..62cfe0d0 100644
--- a/packages/ui/src/components/chat/ModelControls.tsx
+++ b/packages/ui/src/components/chat/ModelControls.tsx
@@ -618,6 +618,7 @@ export const ModelControls: React.FC<ModelControlsProps> = ({
     ];
 
     const prevAgentNameRef = React.useRef<string | undefined>(undefined);
+    const explicitAgentSwitchRef = React.useRef<string | null>(null);
     const latestLoadedUserChoiceRestoreRef = React.useRef<string | null>(null);
 
     const currentSessionDirectory = currentSessionId ? getDirectoryForSession(currentSessionId) : undefined;
@@ -1007,6 +1008,9 @@ export const ModelControls: React.FC<ModelControlsProps> = ({
                     prevAgentNameRef.current = currentAgentName;
 
                     if (currentAgentName && currentSessionId) {
+                        const shouldPreferAgentModel = explicitAgentSwitchRef.current === currentAgentName;
+                        explicitAgentSwitchRef.current = null;
+
                         await new Promise<void>((resolve) => {
                             const timer = setTimeout(resolve, 50);
                             abortController.signal.addEventListener('abort', () => {
@@ -1019,6 +1023,33 @@ export const ModelControls: React.FC<ModelControlsProps> = ({
                             return;
                         }
 
+                        const selectedAgent = shouldPreferAgentModel
+                            ? agents.find((agent) => agent.name === currentAgentName)
+                            : undefined;
+                        if (selectedAgent?.model?.providerID && selectedAgent.model.modelID) {
+                            const result = tryApplyModelSelection(
+                                selectedAgent.model.providerID,
+                                selectedAgent.model.modelID,
+                                currentAgentName,
+                            );
+                            if (result === 'applied' || result === 'provider-missing') {
+                                if (result === 'applied') {
+                                    saveSessionModelSelection(
+                                        currentSessionId,
+                                        selectedAgent.model.providerID,
+                                        selectedAgent.model.modelID,
+                                    );
+                                    saveAgentModelForSession(
+                                        currentSessionId,
+                                        currentAgentName,
+                                        selectedAgent.model.providerID,
+                                        selectedAgent.model.modelID,
+                                    );
+                                }
+                                return;
+                            }
+                        }
+
                         const persistedChoice = getAgentModelForSession(currentSessionId, currentAgentName);
 
                         if (persistedChoice) {
@@ -1043,7 +1074,16 @@ export const ModelControls: React.FC<ModelControlsProps> = ({
         return () => {
             abortController.abort();
         };
-    }, [currentAgentName, currentSessionId, getAgentModelForSession, tryApplyModelSelection, contextHydrated]);
+    }, [
+        agents,
+        currentAgentName,
+        currentSessionId,
+        getAgentModelForSession,
+        saveAgentModelForSession,
+        saveSessionModelSelection,
+        tryApplyModelSelection,
+        contextHydrated,
+    ]);
 
     React.useEffect(() => {
         if (!contextHydrated || !currentAgentName) {
@@ -1119,6 +1159,7 @@ export const ModelControls: React.FC<ModelControlsProps> = ({
 
     const handleAgentChange = React.useCallback((agentName: string, options?: { closeModelSelector?: boolean }) => {
         try {
+            explicitAgentSwitchRef.current = agentName;
             setAgent(agentName);
             addRecentAgent(agentName);
             if (options?.closeModelSelector ?? true) {
diff --git a/packages/ui/src/stores/useConfigStore.ts b/packages/ui/src/stores/useConfigStore.ts
index 9661d0b0..3758b713 100644
--- a/packages/ui/src/stores/useConfigStore.ts
+++ b/packages/ui/src/stores/useConfigStore.ts
@@ -1739,6 +1739,20 @@ export const useConfigStore = create<ConfigStore>()(
                             });
                         };
 
+                        // Prefer the selected agent's configured model when switching agents.
+                        const agent = agents.find((candidate) => candidate.name === agentName);
+                        const agentModelSelection = agent?.model;
+                        if (agentModelSelection?.providerID && agentModelSelection?.modelID) {
+                            const { providerID, modelID } = agentModelSelection;
+                            const agentProvider = providers.find((provider) => provider.id === providerID);
+                            const agentModel = agentProvider?.models.find((model) => model.id === modelID);
+
+                            if (agentModel) {
+                                applyResolvedModelSelection(providerID, modelID, undefined);
+                                return;
+                            }
+                        }
+
                         if (currentSessionId) {
                             const existingAgentModel = useSelectionStore.getState().getAgentModelForSession(currentSessionId, agentName);
                             if (existingAgentModel && hasProviderModel(providers, existingAgentModel.providerId, existingAgentModel.modelId)) {
@@ -1759,11 +1773,7 @@ export const useConfigStore = create<ConfigStore>()(
                             }
                         }
 
-                        if (hasProviderModel(providers, currentProviderId, currentModelId)) {
-                            return;
-                        }
-
-                        // If settings has a default model, use it instead of agent's preferred
+                        // If the agent has no preferred model, use settings default.
                         if (settingsDefaultModel) {
                             const parsed = parseModelString(settingsDefaultModel);
                             if (parsed) {
@@ -1784,18 +1794,7 @@ export const useConfigStore = create<ConfigStore>()(
                             }
                         }
 
-                        // Fall back to agent's preferred model
-                        const agent = agents.find((candidate) => candidate.name === agentName);
-                        const agentModelSelection = agent?.model;
-                        if (agentModelSelection?.providerID && agentModelSelection?.modelID) {
-                            const { providerID, modelID } = agentModelSelection;
-                            const agentProvider = providers.find((provider) => provider.id === providerID);
-                            const agentModel = agentProvider?.models.find((model) => model.id === modelID);
-
-                            if (agentModel) {
-                                applyResolvedModelSelection(providerID, modelID, undefined);
-                            }
-                        }
+                        // Otherwise keep the current valid model selection unchanged.
                     }
                 },