diff --git a/packages/app/src/hooks/use-agent-form-state.ts b/packages/app/src/hooks/use-agent-form-state.ts
index 46b729369..f04a0cbbc 100644
--- a/packages/app/src/hooks/use-agent-form-state.ts
+++ b/packages/app/src/hooks/use-agent-form-state.ts
@@ -372,6 +372,7 @@ export function useAgentFormState(options: UseAgentFormStateOptions = {}): UseAg
       }
       const providerDef = selectableProviderDefinitionMap.get(provider);
       const providerModels = allProviderModels.get(provider) ?? null;
+      const providerPrefs = preferences?.providerPreferences?.[provider];
       const normalizedModelId = normalizeSelectedModelId(modelId);
       const nextModelId = normalizedModelId || resolveDefaultModelId(providerModels);
 
@@ -381,6 +382,7 @@ export function useAgentFormState(options: UseAgentFormStateOptions = {}): UseAg
         modelId,
         providerDef,
         providerModels,
+        providerPrefs,
       });
       void updatePreferences((current) =>
         mergeSelectedComposerPreferences({
@@ -392,7 +394,12 @@ export function useAgentFormState(options: UseAgentFormStateOptions = {}): UseAg
         }),
       );
     },
-    [allProviderModels, selectableProviderDefinitionMap, updatePreferences],
+    [
+      allProviderModels,
+      preferences?.providerPreferences,
+      selectableProviderDefinitionMap,
+      updatePreferences,
+    ],
   );
 
   const setModeFromUser = useCallback(
diff --git a/packages/app/src/provider-selection/resolve-agent-form.test.ts b/packages/app/src/provider-selection/resolve-agent-form.test.ts
index 96e75b3a4..f04fd5fe3 100644
--- a/packages/app/src/provider-selection/resolve-agent-form.test.ts
+++ b/packages/app/src/provider-selection/resolve-agent-form.test.ts
@@ -768,6 +768,21 @@ describe("resolveAgentForm", () => {
       expect(next.userModified.model).toBe(true);
     });
 
+    it("preserves the current preferred mode when selecting a provider and model", () => {
+      const state = makeState({ provider: "codex", modeId: "full-access" });
+      const next = resolveAgentForm(state, {
+        type: "SET_PROVIDER_AND_MODEL_FROM_USER",
+        provider: "codex",
+        modelId: "gpt-5.3-codex",
+        providerDef: TEST_CODEX_DEFINITION,
+        providerModels: CODEX_MODELS,
+      });
+
+      expect(next.form.provider).toBe("codex");
+      expect(next.form.model).toBe("gpt-5.3-codex");
+      expect(next.form.modeId).toBe("full-access");
+    });
+
     it("falls back to provider default model when modelId is empty", () => {
       const state = makeState();
       const next = resolveAgentForm(state, {
diff --git a/packages/app/src/provider-selection/resolve-agent-form.ts b/packages/app/src/provider-selection/resolve-agent-form.ts
index 3763370e2..6cc351188 100644
--- a/packages/app/src/provider-selection/resolve-agent-form.ts
+++ b/packages/app/src/provider-selection/resolve-agent-form.ts
@@ -82,6 +82,7 @@ export type AgentFormAction =
       modelId: string;
       providerDef: AgentProviderDefinition | undefined;
       providerModels: AgentModelDefinition[] | null;
+      providerPrefs?: ProviderPrefs | undefined;
     }
   | { type: "SET_MODE_FROM_USER"; modeId: string }
   | {
@@ -417,6 +418,27 @@ function pickNextModeForProvider(input: {
   return providerDef?.defaultModeId ?? "";
 }
 
+function pickNextModeForProviderAndModel(input: {
+  currentProvider: AgentProvider | null;
+  currentModeId: string;
+  provider: AgentProvider;
+  providerDef: AgentProviderDefinition | undefined;
+  providerPrefs: ProviderPrefs | undefined;
+}): string {
+  const validModeIds = input.providerDef?.modes.map((m) => m.id) ?? [];
+  if (
+    input.currentProvider === input.provider &&
+    input.currentModeId &&
+    validModeIds.includes(input.currentModeId)
+  ) {
+    return input.currentModeId;
+  }
+  return pickNextModeForProvider({
+    providerDef: input.providerDef,
+    providerPrefs: input.providerPrefs,
+  });
+}
+
 function pickNextThinkingOptionForProvider(input: {
   providerModels: AgentModelDefinition[] | null;
   providerPrefs: ProviderPrefs | undefined;
@@ -494,12 +516,19 @@ export function resolveAgentForm(
         modelId: nextModelId,
         requestedThinkingOptionId: "",
       });
+      const nextModeId = pickNextModeForProviderAndModel({
+        currentProvider: state.form.provider,
+        currentModeId: state.form.modeId,
+        provider: action.provider,
+        providerDef: action.providerDef,
+        providerPrefs: action.providerPrefs,
+      });
       return {
         form: {
           ...state.form,
           provider: action.provider,
           model: nextModelId,
-          modeId: action.providerDef?.defaultModeId ?? "",
+          modeId: nextModeId,
           thinkingOptionId: nextThinkingOptionId,
         },
         userModified: { ...state.userModified, provider: true, model: true },