fix(webview): preserve prompt history draft while streaming

webview-ui/src/components/chat/__tests__/ChatTextArea.spec.tsx

@@ -583,6 +583,79 @@ describe("ChatTextArea", () => {
 				expect(setInputValue).toHaveBeenCalledWith("Current input")
 			})
 
+			it("should restore the task-history draft after the first assistant-only stream", () => {
+				const state = {
+					filePaths: [],
+					openedTabs: [],
+					apiConfiguration: { apiProvider: providerIdentifiers.anthropic },
+					taskHistory: [
+						{
+							id: "previous-task",
+							number: 1,
+							ts: 1,
+							task: "Previous task",
+							workspace: "/test/workspace",
+							tokensIn: 0,
+							tokensOut: 0,
+							totalCost: 0,
+						},
+					],
+					clineMessages: [],
+					cwd: "/test/workspace",
+				}
+				vi.mocked(useExtensionState).mockReturnValue({ ...vi.mocked(useExtensionState)(), ...state })
+				const setInputValue = vi.fn()
+				const { container, rerender } = render(
+					<ChatTextArea {...defaultProps} setInputValue={setInputValue} inputValue="Unsent draft" />,
+				)
+				const textarea = container.querySelector("textarea")!
+				textarea.setSelectionRange(0, 0)
+				fireEvent.keyDown(textarea, { key: "ArrowUp" })
+				expect(setInputValue).toHaveBeenLastCalledWith("Previous task")
+
+				vi.mocked(useExtensionState).mockReturnValue({
+					...vi.mocked(useExtensionState)(),
+					clineMessages: [{ ts: 1, type: "say", say: "text", text: "Streaming response", partial: true }],
+				})
+				rerender(<ChatTextArea {...defaultProps} setInputValue={setInputValue} inputValue="Previous task" />)
+				setInputValue.mockClear()
+				textarea.setSelectionRange(textarea.value.length, textarea.value.length)
+				fireEvent.keyDown(textarea, { key: "ArrowDown" })
+				expect(setInputValue).toHaveBeenLastCalledWith("Unsent draft")
+			})
+
+			it("should preserve current input while assistant messages stream", () => {
+				const setInputValue = vi.fn()
+				const { container, rerender } = render(
+					<ChatTextArea {...defaultProps} setInputValue={setInputValue} inputValue="Current input" />,
+				)
+				const textarea = container.querySelector("textarea")!
+
+				textarea.setSelectionRange(0, 0)
+				fireEvent.keyDown(textarea, { key: "ArrowUp" })
+				expect(setInputValue).toHaveBeenCalledWith("Third prompt")
+				;(useExtensionState as ReturnType<typeof vi.fn>).mockReturnValue({
+					filePaths: [],
+					openedTabs: [],
+					apiConfiguration: {
+						apiProvider: providerIdentifiers.anthropic,
+					},
+					taskHistory: [],
+					clineMessages: [
+						...mockClineMessages,
+						{ type: "say", say: "text", text: "Streaming assistant output", ts: 4000 },
+					],
+					cwd: "/test/workspace",
+				})
+				setInputValue.mockClear()
+				rerender(<ChatTextArea {...defaultProps} setInputValue={setInputValue} inputValue="Third prompt" />)
+				textarea.setSelectionRange(textarea.value.length, textarea.value.length)
+
+				fireEvent.keyDown(textarea, { key: "ArrowDown" })
+
+				expect(setInputValue).toHaveBeenCalledWith("Current input")
+			})
+
 			it("should reset history navigation when user types", () => {
 				const setInputValue = vi.fn()
 				const { container } = render(

webview-ui/src/components/chat/hooks/__tests__/usePromptHistory.spec.ts

@@ -0,0 +1,90 @@
+import { ClineMessage, HistoryItem } from "@roo-code/types"
+import { act, renderHook } from "@testing-library/react"
+
+import { usePromptHistory, type UsePromptHistoryReturn } from "../usePromptHistory"
+
+describe("usePromptHistory", () => {
+	it("preserves navigation for assistant-only streams and resets when identical conversation prompts appear", () => {
+		const prompt = "Explain this code"
+		const taskHistory: HistoryItem[] = [
+			{
+				id: "task-1",
+				number: 1,
+				ts: 1,
+				task: prompt,
+				tokensIn: 0,
+				tokensOut: 0,
+				totalCost: 0,
+				workspace: "/workspace",
+			},
+		]
+		const conversationHistory: ClineMessage[] = [{ ts: 2, type: "say", say: "user_feedback", text: prompt }]
+		const setInputValue = vi.fn()
+
+		const { result, rerender } = renderHook<UsePromptHistoryReturn, { clineMessages: ClineMessage[] | undefined }>(
+			({ clineMessages }) =>
+				usePromptHistory({
+					clineMessages,
+					taskHistory,
+					cwd: "/workspace",
+					inputValue: "draft",
+					setInputValue,
+				}),
+			{ initialProps: { clineMessages: [] } },
+		)
+
+		act(() => {
+			result.current.setHistoryIndex(0)
+			result.current.setTempInput("draft")
+		})
+
+		expect(result.current.promptHistory).toEqual([prompt])
+		expect(result.current.historyIndex).toBe(0)
+		expect(result.current.tempInput).toBe("draft")
+
+		rerender({ clineMessages: [{ ts: 2, type: "say", say: "text", text: "Assistant output", partial: true }] })
+
+		expect(result.current.promptHistory).toEqual([prompt])
+		expect(result.current.historyIndex).toBe(0)
+		expect(result.current.tempInput).toBe("draft")
+
+		rerender({ clineMessages: conversationHistory })
+
+		expect(result.current.promptHistory).toEqual([prompt])
+		expect(result.current.historyIndex).toBe(-1)
+		expect(result.current.tempInput).toBe("")
+	})
+
+	it("resets navigation when the current history source gains a prompt", () => {
+		const firstPrompt = "Explain this code"
+		const secondPrompt = "Now simplify it"
+		const initialHistory: ClineMessage[] = [{ ts: 1, type: "say", say: "user_feedback", text: firstPrompt }]
+		const updatedHistory: ClineMessage[] = [
+			...initialHistory,
+			{ ts: 2, type: "say", say: "user_feedback", text: secondPrompt },
+		]
+
+		const { result, rerender } = renderHook<UsePromptHistoryReturn, { clineMessages: ClineMessage[] }>(
+			({ clineMessages }) =>
+				usePromptHistory({
+					clineMessages,
+					taskHistory: undefined,
+					cwd: "/workspace",
+					inputValue: "draft",
+					setInputValue: vi.fn(),
+				}),
+			{ initialProps: { clineMessages: initialHistory } },
+		)
+
+		act(() => {
+			result.current.setHistoryIndex(0)
+			result.current.setTempInput("draft")
+		})
+
+		rerender({ clineMessages: updatedHistory })
+
+		expect(result.current.promptHistory).toEqual([secondPrompt, firstPrompt])
+		expect(result.current.historyIndex).toBe(-1)
+		expect(result.current.tempInput).toBe("")
+	})
+})

webview-ui/src/components/chat/hooks/usePromptHistory.ts

@@ -1,5 +1,5 @@
 import { ClineMessage, HistoryItem } from "@roo-code/types"
-import { useCallback, useEffect, useMemo, useState } from "react"
+import { useCallback, useEffect, useMemo, useRef, useState } from "react"
 
 interface UsePromptHistoryProps {
 	clineMessages: ClineMessage[] | undefined
@@ -38,26 +38,24 @@
 	const [historyIndex, setHistoryIndex] = useState(-1)
 	const [tempInput, setTempInput] = useState("")
 	const [promptHistory, setPromptHistory] = useState<string[]>([])
+	const conversationPrompts = useMemo(
+		() =>
+			clineMessages
+				?.filter((message) => message.type === "say" && message.say === "user_feedback" && message.text?.trim())
+				.map((message) => message.text!),
+		[clineMessages],
+	)
+	const historySource = conversationPrompts?.length ? "conversation" : "task"
+	const previousHistorySource = useRef(historySource)
 
-	// Initialize prompt history with hybrid approach: conversation messages if in task, otherwise task history
+	// Use conversation prompts when available, otherwise keep task history even during assistant-only streams.
 	const filteredPromptHistory = useMemo(() => {
-		// First try to get conversation messages (user_feedback from clineMessages)
-		const conversationPrompts = clineMessages
-			?.filter((message) => message.type === "say" && message.say === "user_feedback" && message.text?.trim())
-			.map((message) => message.text!)
-
 		// If we have conversation messages, use those (newest first when navigating up)
 		if (conversationPrompts?.length) {
 			return conversationPrompts.slice(-MAX_PROMPT_HISTORY_SIZE).reverse()
 		}
 
-		// If we have clineMessages array (meaning we're in an active task), don't fall back to task history
-		// Only use task history when starting fresh (no active conversation)
-		if (clineMessages?.length) {
-			return []
-		}
-
-		// Fall back to task history only when starting fresh (no active conversation)
+		// Fall back to task history until a conversation prompt exists.
 		if (!taskHistory?.length || !cwd) {
 			return []
 		}
@@ -67,15 +65,25 @@
 			.filter((item) => item.task?.trim() && (!item.workspace || item.workspace === cwd))
 			.map((item) => item.task)
 			.slice(0, MAX_PROMPT_HISTORY_SIZE)
-	}, [clineMessages, taskHistory, cwd])
+	}, [conversationPrompts, taskHistory, cwd])
 
 	// Update prompt history when filtered history changes and reset navigation
 	useEffect(() => {
-		setPromptHistory(filteredPromptHistory)
+		const historyChanged =
+			promptHistory.length !== filteredPromptHistory.length ||
+			promptHistory.some((prompt, index) => prompt !== filteredPromptHistory[index])
+		const historySourceChanged = previousHistorySource.current !== historySource
+		previousHistorySource.current = historySource
+
+		if (!historyChanged && !historySourceChanged) return
+
+		if (historyChanged) {
+			setPromptHistory(filteredPromptHistory)
+		}
 		// Reset navigation state when switching between history sources
 		setHistoryIndex(-1)
 		setTempInput("")
-	}, [filteredPromptHistory])
+	}, [filteredPromptHistory, historySource, promptHistory])
 
 	// Reset history navigation when user types (but not when we're setting it programmatically)
 	const resetOnInputChange = useCallback(() => {