diff --git a/src/components/chat/AgentComposer.tsx b/src/components/chat/AgentComposer.tsx
index 5400c7a..40d4c33 100644
--- a/src/components/chat/AgentComposer.tsx
+++ b/src/components/chat/AgentComposer.tsx
@@ -251,7 +251,7 @@ export const AgentComposer = React.forwardRef<AgentComposerHandle, AgentComposer
                   </IconButton>
                 )
               ) : null}
-              <FormControl size="small" sx={{ minWidth: 102 }}>
+              <FormControl size="small" sx={{ minWidth: 96 }}>
                 <Select
                   value={approvalMode}
                   onChange={(event) =>
@@ -260,13 +260,13 @@ export const AgentComposer = React.forwardRef<AgentComposerHandle, AgentComposer
                   disabled={isHydrating || isStreaming}
                   aria-label="权限批准模式"
                   renderValue={(val) => (
-                    <Box sx={{ display: "flex", alignItems: "center", gap: 0.5 }}>
+                    <Box sx={{ display: "flex", alignItems: "center", gap: 0.45 }}>
                       {val === "always" ? (
-                        <AdminPanelSettingsRounded sx={{ fontSize: 16, color: "inherit" }} />
+                        <AdminPanelSettingsRounded sx={{ fontSize: 18, color: "inherit" }} />
                       ) : (
-                        <VerifiedUserRounded sx={{ fontSize: 16, color: "inherit" }} />
+                        <VerifiedUserRounded sx={{ fontSize: 18, color: "inherit" }} />
                       )}
-                      <Typography sx={{ fontSize: "0.78rem", fontWeight: 700, color: "inherit" }}>
+                      <Typography sx={{ fontSize: "0.75rem", fontWeight: 600, color: "inherit" }}>
                         {val === "always" ? "始终允许" : "请求批准"}
                       </Typography>
                     </Box>
@@ -312,6 +312,7 @@ export const AgentComposer = React.forwardRef<AgentComposerHandle, AgentComposer
                       py: 0,
                       pl: 1,
                       pr: "28px !important",
+                      minHeight: 36,
                       display: "flex",
                       alignItems: "center",
                     },
@@ -326,14 +327,14 @@ export const AgentComposer = React.forwardRef<AgentComposerHandle, AgentComposer
                   }}
                 >
                   <MenuItem value="request">
-                    <VerifiedUserRounded className="icon" sx={{ mr: 1.5, mt: 0.2, fontSize: 18, color: "text.secondary" }} />
+                    <VerifiedUserRounded className="icon" sx={{ mr: 1.5, mt: 0.15, fontSize: 18, color: "text.secondary" }} />
                     <Box>
                       <Typography className="title" sx={{ fontSize: "0.85rem", fontWeight: 700, color: "text.primary", mb: 0.2 }}>请求批准</Typography>
                       <Typography sx={{ fontSize: "0.7rem", fontWeight: 500, color: "text.secondary", lineHeight: 1.3 }}>工具权限逐次确认</Typography>
                     </Box>
                   </MenuItem>
                   <MenuItem value="always">
-                    <AdminPanelSettingsRounded className="icon" sx={{ mr: 1.5, mt: 0.2, fontSize: 18, color: "text.secondary" }} />
+                    <AdminPanelSettingsRounded className="icon" sx={{ mr: 1.5, mt: 0.15, fontSize: 18, color: "text.secondary" }} />
                     <Box>
                       <Typography className="title" sx={{ fontSize: "0.85rem", fontWeight: 700, color: "text.primary", mb: 0.2 }}>始终允许</Typography>
                       <Typography sx={{ fontSize: "0.7rem", fontWeight: 500, color: "text.secondary", lineHeight: 1.3 }}>自动允许本轮权限请求</Typography>
diff --git a/src/components/chat/hooks/useAgentChatSession.test.tsx b/src/components/chat/hooks/useAgentChatSession.test.tsx
index d02735f..d7322b5 100644
--- a/src/components/chat/hooks/useAgentChatSession.test.tsx
+++ b/src/components/chat/hooks/useAgentChatSession.test.tsx
@@ -521,4 +521,33 @@ describe("useAgentChatSession", () => {
       expect.anything(),
     );
   });
+
+  it("asks the backend to undo the previous user turn before regenerating", async () => {
+    listChatSessions.mockResolvedValue([]);
+
+    const { result } = renderHook(() =>
+      useAgentChatSession({
+        projectId: "project-1",
+        onToolCall: jest.fn(),
+      }),
+    );
+
+    await waitFor(() => expect(result.current.isHydrating).toBe(false));
+
+    await act(async () => {
+      await result.current.sendPrompt("重新分析压力异常");
+    });
+
+    await act(async () => {
+      await result.current.regenerate();
+    });
+
+    expect(streamAgentChat).toHaveBeenNthCalledWith(
+      2,
+      expect.objectContaining({
+        message: "重新分析压力异常",
+        regenerateFromMessageIndex: 0,
+      }),
+    );
+  });
 });
diff --git a/src/components/chat/hooks/useAgentChatSession.ts b/src/components/chat/hooks/useAgentChatSession.ts
index 8ea558a..f9145d2 100644
--- a/src/components/chat/hooks/useAgentChatSession.ts
+++ b/src/components/chat/hooks/useAgentChatSession.ts
@@ -56,6 +56,7 @@ type UseAgentChatSessionOptions = {
 type PromptRunOptions = {
   prompt: string;
   sessionIdOverride?: string;
+  regenerateFromMessageIndex?: number;
   preparedMessages?: Message[];
   userMessage?: Message;
   assistantMessage?: Message;
@@ -609,6 +610,7 @@ export const useAgentChatSession = ({
     async ({
       prompt: rawPrompt,
       sessionIdOverride,
+      regenerateFromMessageIndex,
       preparedMessages,
       userMessage,
       assistantMessage,
@@ -644,6 +646,7 @@ export const useAgentChatSession = ({
           sessionId: sessionIdOverride ?? sessionIdRef.current,
           model: getModel?.(),
           approvalMode: getApprovalMode?.(),
+          regenerateFromMessageIndex,
           signal: controller.signal,
           onEvent: (event) =>
             applyStreamEvent(event, {
@@ -991,6 +994,7 @@ export const useAgentChatSession = ({
       setMessages(nextMessages);
       await runPrompt({
         prompt: lastUserContent,
+        regenerateFromMessageIndex: lastUserIndex,
         preparedMessages: [
           ...nextMessages,
           nextUserMessage,
diff --git a/src/lib/chatStream.test.ts b/src/lib/chatStream.test.ts
index bda5744..5477c02 100644
--- a/src/lib/chatStream.test.ts
+++ b/src/lib/chatStream.test.ts
@@ -73,6 +73,7 @@ describe("streamAgentChat", () => {
           session_id: undefined,
           model: "deepseek/deepseek-v4-pro",
           approval_mode: undefined,
+          regenerate_from_message_index: undefined,
         }),
       }),
     );
diff --git a/src/lib/chatStream.ts b/src/lib/chatStream.ts
index 7b4a2e9..88f6948 100644
--- a/src/lib/chatStream.ts
+++ b/src/lib/chatStream.ts
@@ -71,6 +71,7 @@ type StreamOptions = {
   sessionId?: string;
   model?: AgentModel;
   approvalMode?: AgentApprovalMode;
+  regenerateFromMessageIndex?: number;
   signal?: AbortSignal;
   onEvent: (event: StreamEvent) => void;
 };
@@ -286,6 +287,7 @@ export const streamAgentChat = async ({
   sessionId,
   model,
   approvalMode,
+  regenerateFromMessageIndex,
   signal,
   onEvent,
 }: StreamOptions) => {
@@ -305,6 +307,7 @@ export const streamAgentChat = async ({
           session_id: sessionId,
           model,
           approval_mode: approvalMode,
+          regenerate_from_message_index: regenerateFromMessageIndex,
         }),
         projectHeaderMode: "include",
         userHeaderMode: "include",