fix(tui): let the prompt Down arrow reach the end of the text

packages/opencode/src/cli/cmd/run/footer.prompt.tsx

@@ -21,6 +21,9 @@ import {
   mentionTriggerIndex,
   isNewCommand,
   movePromptHistory,
+  promptOffsetWidth,
+  promptOnFirstRow,
+  promptOnLastRow,
   pushPromptHistory,
 } from "./prompt.shared"
 import { OPENCODE_BASE_MODE, useBindings } from "@opencode-ai/tui/keymap"
@@ -591,7 +594,7 @@ export function createPromptState(input: PromptInput): PromptState {
     })
   }
 
-  const restore = (value: RunPrompt, cursor = Bun.stringWidth(value.text)) => {
+  const restore = (value: RunPrompt, cursor = promptOffsetWidth(value.text)) => {
     draft = clonePrompt(value)
     setShell(value.mode === "shell")
     if (!area || area.isDestroyed) {
@@ -601,7 +604,7 @@ export function createPromptState(input: PromptInput): PromptState {
     hide()
     area.setText(value.text)
     restoreParts(value.parts)
-    area.cursorOffset = Math.min(cursor, Bun.stringWidth(area.plainText))
+    area.cursorOffset = Math.min(cursor, promptOffsetWidth(area.plainText))
     scheduleRows()
     area.focus()
   }
@@ -632,7 +635,7 @@ export function createPromptState(input: PromptInput): PromptState {
     area.setText(text)
     clearParts()
     draft = shell() ? { text: area.plainText, parts: [], mode: "shell" } : { text: area.plainText, parts: [] }
-    area.cursorOffset = Math.min(Bun.stringWidth(text), Bun.stringWidth(area.plainText))
+    area.cursorOffset = Math.min(promptOffsetWidth(text), promptOffsetWidth(area.plainText))
     scheduleRows()
     area.focus()
   }
@@ -766,19 +769,15 @@ export function createPromptState(input: PromptInput): PromptState {
     if (move(dir, event)) return
     if (!area || area.isDestroyed) return false
 
-    const endOffset = Bun.stringWidth(area.plainText)
-    if (dir === -1 && area.visualCursor.visualRow === 0) {
-      area.cursorOffset = 0
+    if (dir === -1 && promptOnFirstRow(area)) {
+      area.gotoBufferHome()
     }
 
-    const end =
-      typeof area.height === "number" && Number.isFinite(area.height) && area.height > 0
-        ? area.height - 1
-        : Math.max(0, (area.virtualLineCount ?? 1) - 1)
-    if (dir === 1 && area.visualCursor.visualRow === end) {
-      area.cursorOffset = endOffset
+    if (dir === 1 && promptOnLastRow(area)) {
+      area.gotoBufferEnd()
     }
 
+    // Reject so the textarea layer still moves the cursor one row.
     return false
   }
 
@@ -871,13 +870,13 @@ export function createPromptState(input: PromptInput): PromptState {
         shell() || !head
           ? cursor
           : local
-            ? Bun.stringWidth(area.plainText)
-            : Bun.stringWidth(area.plainText.slice(0, head.end))
+            ? promptOffsetWidth(area.plainText)
+            : promptOffsetWidth(area.plainText.slice(0, head.end))
       const end = area.logicalCursor
 
       area.deleteRange(start.row, start.col, end.row, end.col)
       area.insertText(text)
-      area.cursorOffset = Bun.stringWidth(text)
+      area.cursorOffset = promptOffsetWidth(text)
       hide()
       syncDraft()
       if (!shell()) {
@@ -902,7 +901,7 @@ export function createPromptState(input: PromptInput): PromptState {
 
     const text = "@" + next.value
     const startOffset = at()
-    const endOffset = startOffset + Bun.stringWidth(text)
+    const endOffset = startOffset + promptOffsetWidth(text)
     const part = structuredClone(next.part)
     if (part.type === "agent") {
       part.source = {

packages/opencode/src/cli/cmd/run/prompt.shared.ts

@@ -7,7 +7,15 @@
 // the current browse position. When the user arrows up at cursor offset 0,
 // the current draft is saved and history begins. Arrowing past the end
 // restores the draft.
-export { displayCharAt, displaySlice, mentionTriggerIndex } from "../prompt-display"
+export {
+  displayCharAt,
+  displaySlice,
+  mentionTriggerIndex,
+  promptOffsetWidth,
+  promptOnFirstRow,
+  promptOnLastRow,
+} from "../prompt-display"
+import { promptOffsetWidth } from "../prompt-display"
 import type { RunPrompt } from "./types"
 
 const HISTORY_LIMIT = 200
@@ -102,7 +110,7 @@ export function movePromptHistory(state: PromptHistoryState, dir: -1 | 1, text:
     return { state, apply: false }
   }
 
-  if (dir === 1 && cursor !== Bun.stringWidth(text)) {
+  if (dir === 1 && cursor !== promptOffsetWidth(text)) {
     return { state, apply: false }
   }
 
@@ -136,7 +144,7 @@ export function movePromptHistory(state: PromptHistoryState, dir: -1 | 1, text:
         index: null,
       },
       text: state.draft,
-      cursor: Bun.stringWidth(state.draft),
+      cursor: promptOffsetWidth(state.draft),
       apply: true,
     }
   }
@@ -147,7 +155,7 @@ export function movePromptHistory(state: PromptHistoryState, dir: -1 | 1, text:
       index: idx,
     },
     text: state.items[idx].text,
-    cursor: dir === -1 ? 0 : Bun.stringWidth(state.items[idx].text),
+    cursor: dir === -1 ? 0 : promptOffsetWidth(state.items[idx].text),
     apply: true,
   }
 }

packages/opencode/test/cli/run/footer.prompt.cursor.test.tsx

@@ -0,0 +1,208 @@
+/** @jsxImportSource @opentui/solid */
+import { expect, test } from "bun:test"
+import { testRender, useRenderer } from "@opentui/solid"
+import { createSignal } from "solid-js"
+import { createDefaultOpenTuiKeymap } from "@opentui/keymap/opentui"
+import { OpencodeKeymapProvider, registerOpencodeKeymap } from "@opencode-ai/tui/keymap"
+import { RunFooterView } from "@/cli/cmd/run/footer.view"
+import { RUN_THEME_FALLBACK } from "@/cli/cmd/run/theme"
+import { promptOffsetWidth } from "@opencode-ai/tui/prompt/display"
+import type { FooterState, FooterSubagentState, FooterView, RunPrompt } from "@/cli/cmd/run/types"
+import { createTuiResolvedConfig } from "../../fixture/tui-runtime"
+
+const tuiConfig = createTuiResolvedConfig()
+
+async function renderComposer(input: { history?: RunPrompt[] } = {}) {
+  const [view] = createSignal<FooterView>({ type: "prompt" })
+  const [subagents] = createSignal<FooterSubagentState>({ tabs: [], details: {}, permissions: [], questions: [] })
+  const [state] = createSignal<FooterState>({
+    phase: "idle",
+    status: "",
+    queue: 0,
+    model: "gpt-5",
+    duration: "",
+    usage: "",
+    first: true,
+    interrupt: 0,
+    exit: 0,
+  })
+  let offKeymap: (() => void) | undefined
+
+  function Harness() {
+    const renderer = useRenderer()
+    const keymap = createDefaultOpenTuiKeymap(renderer)
+    offKeymap = registerOpencodeKeymap(keymap, renderer, tuiConfig)
+
+    return (
+      <OpencodeKeymapProvider keymap={keymap}>
+        <RunFooterView
+          directory="/tmp"
+          findFiles={async () => []}
+          agents={() => []}
+          resources={() => []}
+          commands={() => []}
+          providers={() => undefined}
+          currentModel={() => undefined}
+          variants={() => []}
+          currentVariant={() => undefined}
+          state={state}
+          view={view}
+          subagent={subagents}
+          theme={() => RUN_THEME_FALLBACK}
+          tuiConfig={tuiConfig}
+          backgroundSubagents={true}
+          agent="opencode"
+          history={input.history}
+          onSubmit={() => true}
+          onPermissionReply={() => {}}
+          onQuestionReply={() => {}}
+          onQuestionReject={() => {}}
+          onCycle={() => {}}
+          onInterrupt={() => false}
+          onEditorOpen={async () => undefined}
+          onInputClear={() => {}}
+          onExit={() => {}}
+          onModelSelect={() => {}}
+          onVariantSelect={() => {}}
+          onRows={() => {}}
+          onLayout={() => {}}
+          onStatus={() => {}}
+          onQueuedRemove={async () => true}
+        />
+      </OpencodeKeymapProvider>
+    )
+  }
+
+  const app = await testRender(
+    () => (
+      <box width={40} height={16}>
+        <Harness />
+      </box>
+    ),
+    { width: 40, height: 16, kittyKeyboard: true },
+  )
+  await app.renderOnce()
+
+  return {
+    ...app,
+    area() {
+      return app.renderer.currentFocusedEditor!
+    },
+    async press(dir: "up" | "down", times: number) {
+      for (let i = 0; i < times; i++) {
+        app.mockInput.pressArrow(dir)
+        await app.renderOnce()
+      }
+    },
+    cleanup() {
+      app.renderer.currentFocusedRenderable?.blur()
+      app.renderer.currentFocusedEditor?.blur()
+      offKeymap?.()
+      offKeymap = undefined
+      app.renderer.destroy()
+    },
+  }
+}
+
+test("direct composer down arrow walks a multi-line prompt to its end", async () => {
+  const app = await renderComposer()
+
+  try {
+    const area = app.area()
+    area.setText("one\ntwo\nthree")
+    await app.renderOnce()
+    const end = promptOffsetWidth(area.plainText)
+
+    // Middle of the second line. Each newline costs one offset position, so the
+    // end offset is 13 here while Bun.stringWidth would report 11.
+    area.cursorOffset = 5
+    await app.renderOnce()
+    await app.press("down", 1)
+    expect(area.cursorOffset).toBe(9)
+
+    await app.press("down", 3)
+    expect(area.cursorOffset).toBe(end)
+  } finally {
+    app.cleanup()
+  }
+})
+
+test("direct composer down arrow reaches the end of wide-character text", async () => {
+  const app = await renderComposer()
+
+  try {
+    const area = app.area()
+    area.setText("你好世界\n第二行文字\n第三行")
+    await app.renderOnce()
+
+    area.gotoBufferHome()
+    await app.renderOnce()
+    await app.press("down", 6)
+    expect(area.cursorOffset).toBe(promptOffsetWidth(area.plainText))
+  } finally {
+    app.cleanup()
+  }
+})
+
+test("direct composer arrows never move backwards in a scrolled prompt", async () => {
+  const app = await renderComposer()
+
+  try {
+    const area = app.area()
+    // Eight lines against TEXTAREA_MAX_ROWS (6) forces the viewport to scroll.
+    area.setText("l1\nl2\nl3\nl4\nl5\nl6\nl7\nl8")
+    await app.renderOnce()
+    area.gotoBufferHome()
+    await app.renderOnce()
+
+    const seen = [area.cursorOffset]
+    for (let i = 0; i < 9; i++) {
+      app.mockInput.pressArrow("down")
+      await app.renderOnce()
+      expect(area.cursorOffset).toBeGreaterThanOrEqual(seen[seen.length - 1])
+      seen.push(area.cursorOffset)
+    }
+    expect(area.cursorOffset).toBe(promptOffsetWidth(area.plainText))
+  } finally {
+    app.cleanup()
+  }
+})
+
+test("direct composer up arrow walks a multi-line prompt to its start", async () => {
+  const app = await renderComposer()
+
+  try {
+    const area = app.area()
+    area.setText("你好世界\n第二行文字\n第三行")
+    await app.renderOnce()
+    area.gotoBufferEnd()
+    await app.renderOnce()
+
+    await app.press("up", 6)
+    expect(area.cursorOffset).toBe(0)
+  } finally {
+    app.cleanup()
+  }
+})
+
+test("direct composer recalls history from the end of a multi-line draft", async () => {
+  const app = await renderComposer({ history: [{ text: "older prompt", parts: [] }] })
+
+  try {
+    const area = app.area()
+    area.setText("draft one\ndraft two")
+    await app.renderOnce()
+    area.gotoBufferEnd()
+    await app.renderOnce()
+
+    // Up walks to the top of the draft, then swaps in the history entry.
+    await app.press("up", 3)
+    expect(area.plainText).toBe("older prompt")
+
+    // Down at the end of the entry restores the draft rather than stalling.
+    await app.press("down", 2)
+    expect(area.plainText).toBe("draft one\ndraft two")
+  } finally {
+    app.cleanup()
+  }
+})

packages/tui/src/component/prompt/index.tsx

@@ -28,7 +28,7 @@ import { useEvent } from "../../context/event"
 import { editorSelectionKey, useEditorContext, type EditorSelection } from "../../context/editor"
 import { normalizePromptContent, openEditor } from "../../editor"
 import { useExit } from "../../context/exit"
-import { promptOffsetWidth } from "../../prompt/display"
+import { promptOffsetWidth, promptOnFirstRow, promptOnLastRow } from "../../prompt/display"
 import { createStore, produce, unwrap } from "solid-js/store"
 import { usePromptHistory, type PromptInfo } from "../../prompt/history"
 import { computePromptTraits } from "../../prompt/traits"
@@ -508,7 +508,7 @@ export function Prompt(props: PromptProps) {
             parts: updatedNonTextParts,
           })
           restoreExtmarksFromParts(updatedNonTextParts)
-          input.cursorOffset = Bun.stringWidth(normalized)
+          input.gotoBufferEnd()
         },
       },
       {
@@ -872,7 +872,7 @@ export function Prompt(props: PromptProps) {
           category: "Prompt",
           run() {
             if (input.cursorOffset !== 0) {
-              if (input.scrollY + input.visualCursor.visualRow === 0) input.cursorOffset = 0
+              if (promptOnFirstRow(input)) input.gotoBufferHome()
               return false
             }
 
@@ -903,12 +903,8 @@ export function Prompt(props: PromptProps) {
           title: "Next prompt history",
           category: "Prompt",
           run() {
-            if (input.cursorOffset !== input.plainText.length) {
-              if (
-                input.scrollY + input.visualCursor.visualRow ===
-                Math.max(0, input.editorView.getTotalVirtualLineCount() - 1)
-              )
-                input.cursorOffset = input.plainText.length
+            if (input.cursorOffset !== promptOffsetWidth(input.plainText)) {
+              if (promptOnLastRow(input)) input.gotoBufferEnd()
               return false
             }
 
@@ -918,7 +914,7 @@ export function Prompt(props: PromptProps) {
             setStore("prompt", item)
             setStore("mode", item.mode ?? "normal")
             restoreExtmarksFromParts(item.parts)
-            input.cursorOffset = input.plainText.length
+            input.gotoBufferEnd()
           },
         },
       ],