FIX Improve single-turn chat controls and first-prompt branching

frontend/README.md

@@ -29,6 +29,13 @@ conversations), open the
 conversation panel, and select the copy at its full
 `/attacks/{attack_id}/conversations/{conversation_id}` URL. Copying
 within a target-free attack keeps it target-free until you send a prompt.
+For single-turn targets or targets that cannot replay the first prompt as history,
+**Branch conversation** on that first user turn restores it to the prompt box
+without copying the response. After a successful single send, **Undo last send**
+also restores the prompt in a new conversation, if the target can replay the
+preceding history. Both actions restore the saved prompt and converter results
+for text, image, audio, video, and mixed responses. They do not overwrite new
+prompt edits or changed converter pipelines.
 When you save an edited conversation, its final user turn moves to the prompt
 box instead of saved history. Text and attachments retain their metadata,
 including text-only video remix IDs. You can enter and edit prompts without a target.

frontend/src/components/Chat/ChatInputArea.test.tsx

@@ -38,7 +38,6 @@ describe("ChatInputArea", () => {
   const defaultProps = {
     onSend: jest.fn().mockResolvedValue(sentOutcome),
     disabled: false,
-    onNewConversation: jest.fn(),
     onUseAsTemplate: jest.fn(),
     onConfigureTarget: jest.fn(),
     onToggleConverterPanel: jest.fn(),
@@ -105,14 +104,15 @@ describe("ChatInputArea", () => {
   it("should keep Undo reachable for an eligible first-turn undo when a single-turn prompt is disabled", async () => {
     const user = userEvent.setup();
     const onUndo = jest.fn();
-    render(<TestWrapper><ChatInputArea {...defaultProps} disabled singleTurnLimitReached
+    render(<TestWrapper><ChatInputArea {...defaultProps} disabled
+      disabledReasons={["This target only supports single-turn conversations."]}
       undoLastSend={{ isUndoing: false, onUndo }} /></TestWrapper>);
     expect(screen.getByRole("textbox")).toBeDisabled();
     expect(screen.getByRole("button", { name: "Toggle converter panel" })).toBeDisabled();
     expect(screen.getByRole("button", { name: "Undo last send" })).toBeEnabled();
     await user.click(screen.getByRole("button", { name: "Undo last send" }));
     expect(onUndo).toHaveBeenCalledTimes(1);
-    expect(screen.getByTestId("single-turn-banner")).toBeInTheDocument();
+    expect(screen.queryByTestId("single-turn-banner")).not.toBeInTheDocument();
   });
 
   it("should retain the disabled Undo explanation in the prompt box", async () => {
@@ -934,7 +934,7 @@ describe("ChatInputArea", () => {
 
     expect(
       screen.getByText(
-        /does not track conversation history/
+        /only supports single-turn conversations/
       )
     ).toBeInTheDocument();
   });
@@ -1200,62 +1200,30 @@ describe("ChatInputArea", () => {
     expect(screen.queryByText(/\(\s*\d+(?:\.\d+)?\s*[KM]?B\s*\)/)).toBeNull();
   });
 
-  it("should show single-turn banner when singleTurnLimitReached is true", () => {
-    render(
-      <TestWrapper>
-        <ChatInputArea
-          {...defaultProps}
-          singleTurnLimitReached={true}
-          onNewConversation={jest.fn()}
-        />
-      </TestWrapper>
-    );
-
-    expect(screen.getByTestId("single-turn-banner")).toBeInTheDocument();
-    expect(screen.getByText(/only supports single-turn/)).toBeInTheDocument();
-    expect(screen.getByTestId("new-conversation-btn")).toBeInTheDocument();
-    // Input area should not be rendered
-    expect(screen.queryByRole("textbox")).not.toBeInTheDocument();
-  });
-
-  it("should call onNewConversation when New Conversation button clicked", async () => {
+  it.each([false, true])("keeps the disabled single-turn composer visible with Undo present=%s", async (withUndo: boolean) => {
     const user = userEvent.setup();
-    const onNewConversation = jest.fn();
-
-    render(
-      <TestWrapper>
-        <ChatInputArea
-          {...defaultProps}
-          singleTurnLimitReached={true}
-          onNewConversation={onNewConversation}
-        />
-      </TestWrapper>
-    );
-
-    await user.click(screen.getByTestId("new-conversation-btn"));
-    expect(onNewConversation).toHaveBeenCalledTimes(1);
-  });
-
-  it("should show New Conversation button when singleTurnLimitReached", () => {
-    render(
-      <TestWrapper>
-        <ChatInputArea
-          {...defaultProps}
-          singleTurnLimitReached={true}
-        />
-      </TestWrapper>
-    );
-
-    expect(screen.getByTestId("single-turn-banner")).toBeInTheDocument();
-    expect(screen.getByTestId("new-conversation-btn")).toBeInTheDocument();
+    render(<TestWrapper><ChatInputArea {...defaultProps} disabled
+      disabledReasons={["This target only supports single-turn conversations."]}
+      undoLastSend={withUndo ? { onUndo: jest.fn(), isUndoing: false, disabledReason: "No saved converter state." } : undefined}
+    /></TestWrapper>);
+    expect(screen.getByRole("textbox")).toBeDisabled();
+    expect(screen.queryByTestId("single-turn-banner")).not.toBeInTheDocument();
+    expect(screen.queryByTestId("new-conversation-btn")).not.toBeInTheDocument();
+    await user.click(screen.getByLabelText("Why the prompt box is disabled"));
+    expect(screen.getByRole("listitem")).toHaveTextContent("This target only supports single-turn conversations.");
+    expect(screen.queryByText(/Wait for the current operation/)).not.toBeInTheDocument();
+    await user.keyboard("{Escape}");
+    await user.hover(getSendButton());
+    expect(await screen.findByRole("tooltip")).toHaveTextContent("This target only supports single-turn conversations.");
+    await user.click(getSendButton());
+    expect(defaultProps.onSend).not.toHaveBeenCalled();
   });
 
-  it("should show normal input when singleTurnLimitReached is false", () => {
+  it("should show normal input before a single-turn send", () => {
     render(
       <TestWrapper>
         <ChatInputArea
           {...defaultProps}
-          singleTurnLimitReached={false}
         />
       </TestWrapper>
     );

frontend/src/components/Chat/ChatInputArea.tsx

@@ -1,7 +1,7 @@
 import { useState, useCallback, useEffect, useLayoutEffect, useRef, forwardRef, useImperativeHandle, type KeyboardEvent } from 'react'
 
 import { Button, Caption1, Popover, PopoverSurface, PopoverTrigger, Tooltip, Text } from '@fluentui/react-components'
-import { SendRegular, DismissRegular, InfoRegular, AddRegular, CopyRegular, WarningRegular, SettingsRegular, ArrowSyncRegular } from '@fluentui/react-icons'
+import { SendRegular, DismissRegular, InfoRegular, CopyRegular, WarningRegular, SettingsRegular, ArrowSyncRegular } from '@fluentui/react-icons'
 
 import type { AttackTargetResolutionStatus, ChatSendOutcome, ConvertedFileChip, MessageAttachment, MultiSendOptions, PieceConversion, TargetInstance, UndoLastSendAction } from '@/types'
 import { isTargetResolutionBlocking } from '@/utils/targetIdentity'
@@ -120,8 +120,6 @@ interface ChatInputAreaProps {
   sendDisabled?: boolean
   sendDisabledReasons?: string[]
   activeTarget?: TargetInstance | null
-  singleTurnLimitReached?: boolean
-  onNewConversation?: () => void
   operatorLocked?: boolean
   crossTargetLocked?: boolean
   targetResolutionStatus?: AttackTargetResolutionStatus
@@ -154,7 +152,7 @@ interface ChatInputAreaProps {
 
 const ChatInputArea = forwardRef<ChatInputAreaHandle, ChatInputAreaProps>(function ChatInputArea({
   onSend, conversionRevisionKey = '', disabled = false, disabledReasons = [], sendDisabled = false, sendDisabledReasons = [], activeTarget,
-  singleTurnLimitReached = false, onNewConversation, operatorLocked = false, crossTargetLocked = false,
+  operatorLocked = false, crossTargetLocked = false,
   targetResolutionStatus = 'idle', onRetryTargetResolution, onUseAsTemplate, attackOperator, onConfigureTarget,
   onToggleConverterPanel, isConverterPanelOpen = false, onInputChange, onAttachmentsChange,
   convertedValue, onClearConversion, onClearAllConversions, onConvertedValueChange,
@@ -293,17 +291,8 @@ const ChatInputArea = forwardRef<ChatInputAreaHandle, ChatInputAreaProps>(functi
           text="This attack uses a different target. Continue with your target to keep the conversation."
           buttonText="Continue with your target" buttonIcon={<CopyRegular />} onButtonClick={onUseAsTemplate}
           testId="cross-target-banner" buttonTestId="use-as-template-btn" buttonClassName={styles.touchTarget} />
-      ) : singleTurnLimitReached && !undoLastSend ? (
-        <StatusBanner className={styles.statusBanner} textClassName={styles.statusBannerText} icon={<InfoRegular fontSize={18} />}
-          text="This target only supports single-turn conversations." buttonText="New Conversation" buttonIcon={<AddRegular />}
-          onButtonClick={onNewConversation} testId="single-turn-banner"
-          buttonTestId="new-conversation-btn" buttonClassName={styles.touchTarget} />
       ) : (
         <>
-        {singleTurnLimitReached && <StatusBanner className={styles.statusBanner} textClassName={styles.statusBannerText}
-          icon={<InfoRegular fontSize={18} />} text="This target only supports single-turn conversations."
-          buttonText="New Conversation" buttonIcon={<AddRegular />} onButtonClick={onNewConversation}
-          testId="single-turn-banner" buttonTestId="new-conversation-btn" buttonClassName={styles.touchTarget} />}
         <div className={styles.composerTrigger}>
           <PromptEditor text={input} attachments={attachments} onInputChange={changeText} onAttachmentsChange={changeAttachments}
             disabled={disabled} textareaRef={textareaRef} onKeyDown={handleKeyDown}
@@ -323,7 +312,7 @@ const ChatInputArea = forwardRef<ChatInputAreaHandle, ChatInputAreaProps>(functi
               <MultiSendSettings options={effectiveSendOptions} disabled={disabled || sendDisabled}
                 disabledReason={repeatDisabledReason} onChange={setSendOptions} />
               {activeTarget?.capabilities?.supports_multi_turn === false && <Tooltip
-                content="This target does not track conversation history — each turn is sent independently." relationship="description">
+                content="This target only supports single-turn conversations." relationship="description">
                 <span className={styles.singleTurnWarning}><InfoRegular fontSize={18} /></span>
               </Tooltip>}
               <Tooltip content={sendTooltip} relationship="description">