fix(webview-ui): keep @ context picker open when selecting a folder via Enter/Tab

Insert folder mentions without trailing space so the picker remains active. Keep the picker open and immediately query folder children to enable keyboard drilldown. Add a focused test for folder drilldown behavior. Fixes #8076.

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

@@ -342,6 +342,72 @@ export const ChatTextArea = forwardRef<HTMLTextAreaElement, ChatTextAreaProps>(
 					}
 				}
 
+				// Special handling for concrete folder selections:
+				// - Keep the picker open
+				// - Ensure trailing slash
+				// - Insert without trailing space
+				// - Trigger a follow-up search to show folder contents
+				if (type === ContextMenuOptionType.Folder && value && textAreaRef.current) {
+					// Normalize folder path to end with a trailing slash
+					let folderPath = value
+					if (!folderPath.endsWith("/")) {
+						folderPath = folderPath + "/"
+					}
+
+					// Manually build insertion without a trailing space (more deterministic than insertMention)
+					const original = textAreaRef.current.value
+					const beforeCursor = original.slice(0, cursorPosition)
+					const afterCursor = original.slice(cursorPosition)
+					const lastAtIndex = beforeCursor.lastIndexOf("@")
+
+					let beforeMention = beforeCursor
+					let afterCursorContent = afterCursor
+
+					if (lastAtIndex !== -1) {
+						// Replace everything from '@' to cursor with the folder path
+						beforeMention = original.slice(0, lastAtIndex)
+						// Match insertMention behavior for non-space-delimited languages
+						const isAlphaNumSpace = /^[a-zA-Z0-9\s]*$/.test(afterCursor)
+						afterCursorContent = isAlphaNumSpace ? afterCursor.replace(/^[^\s]*/, "") : afterCursor
+					}
+
+					const updatedValue = beforeMention + "@" + folderPath + afterCursorContent
+					const afterMentionPos =
+						(lastAtIndex !== -1 ? lastAtIndex : beforeCursor.length) + 1 + folderPath.length
+
+					setInputValue(updatedValue)
+					setCursorPosition(afterMentionPos)
+					setIntendedCursorPosition(afterMentionPos)
+
+					// Keep the context menu open for drill-down
+					setShowContextMenu(true)
+					setSelectedType(null)
+
+					// Compute the next-level query (text after '@' up to the caret)
+					const nextQuery = updatedValue.slice(
+						(lastAtIndex !== -1 ? lastAtIndex : beforeCursor.length) + 1,
+						afterMentionPos,
+					)
+					setSearchQuery(nextQuery)
+
+					// Kick off a search to populate folder children
+					const reqId = Math.random().toString(36).substring(2, 9)
+					setSearchRequestId(reqId)
+					setSearchLoading(true)
+					vscode.postMessage({
+						type: "searchFiles",
+						query: unescapeSpaces(nextQuery),
+						requestId: reqId,
+					})
+
+					// Keep focus in the textarea for continued typing
+					setTimeout(() => {
+						textAreaRef.current?.focus()
+					}, 0)
+
+					return
+				}
+
 				setShowContextMenu(false)
 				setSelectedType(null)
 

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

@@ -0,0 +1,96 @@
+import React from "react"
+import { render, fireEvent, screen } from "@src/utils/test-utils"
+import { useExtensionState } from "@src/context/ExtensionStateContext"
+import { vscode } from "@src/utils/vscode"
+import { ContextMenuOptionType } from "@src/utils/context-mentions"
+import { ChatTextArea } from "../ChatTextArea"
+
+// Mock VS Code messaging
+vi.mock("@src/utils/vscode", () => ({
+	vscode: {
+		postMessage: vi.fn(),
+	},
+}))
+
+// Capture the last props passed to ContextMenu so we can invoke onSelect directly
+let lastContextMenuProps: any = null
+vi.mock("../ContextMenu", () => {
+	return {
+		__esModule: true,
+		default: (props: any) => {
+			lastContextMenuProps = props
+			return <div data-testid="context-menu" />
+		},
+		__getLastProps: () => lastContextMenuProps,
+	}
+})
+
+// Mock ExtensionStateContext
+vi.mock("@src/context/ExtensionStateContext")
+
+describe("ChatTextArea - folder drilldown behavior", () => {
+	const defaultProps = {
+		inputValue: "",
+		setInputValue: vi.fn(),
+		onSend: vi.fn(),
+		sendingDisabled: false,
+		selectApiConfigDisabled: false,
+		onSelectImages: vi.fn(),
+		shouldDisableImages: false,
+		placeholderText: "Type a message...",
+		selectedImages: [],
+		setSelectedImages: vi.fn(),
+		onHeightChange: vi.fn(),
+		mode: "architect",
+		setMode: vi.fn(),
+		modeShortcutText: "(⌘. for next mode)",
+	}
+
+	beforeEach(() => {
+		vi.clearAllMocks()
+		;(useExtensionState as ReturnType<typeof vi.fn>).mockReturnValue({
+			filePaths: ["src/", "src/index.ts"],
+			openedTabs: [],
+			taskHistory: [],
+			cwd: "/test/workspace",
+		})
+	})
+
+	it("keeps picker open and triggers folder children search when selecting a folder", () => {
+		const setInputValue = vi.fn()
+
+		const { container } = render(<ChatTextArea {...defaultProps} setInputValue={setInputValue} />)
+
+		// Type to open the @-context menu and set a query
+		const textarea = container.querySelector("textarea")!
+		fireEvent.change(textarea, {
+			target: { value: "@s", selectionStart: 2 },
+		})
+
+		// Ensure our mocked ContextMenu rendered and captured props
+		expect(screen.getByTestId("context-menu")).toBeInTheDocument()
+		const props = lastContextMenuProps
+		expect(props).toBeTruthy()
+		expect(typeof props.onSelect).toBe("function")
+
+		// Simulate selecting a concrete folder suggestion (e.g. "/src")
+		props.onSelect(ContextMenuOptionType.Folder, "/src")
+
+		// The input should contain "@/src/" with NO trailing space and the picker should remain open
+		expect(setInputValue).toHaveBeenCalled()
+		const finalValue = setInputValue.mock.calls.at(-1)?.[0]
+		expect(finalValue).toBe("@/src/")
+
+		// Context menu should still be present (picker remains open)
+		expect(screen.getByTestId("context-menu")).toBeInTheDocument()
+
+		// It should have kicked off a searchFiles request for the folder children
+		const pm = vscode.postMessage as ReturnType<typeof vi.fn>
+		expect(pm).toHaveBeenCalled()
+		const lastMsg = pm.mock.calls.at(-1)?.[0]
+		expect(lastMsg).toMatchObject({ type: "searchFiles" })
+		// Query mirrors substring after '@' including leading slash per existing logic
+		expect(lastMsg.query).toBe("/src/")
+		expect(typeof lastMsg.requestId).toBe("string")
+	})
+})