diff --git a/ui-tui/src/__tests__/textInputLineNav.test.ts b/ui-tui/src/__tests__/textInputLineNav.test.ts
new file mode 100644
index 0000000000..56b3772a9f
--- /dev/null
+++ b/ui-tui/src/__tests__/textInputLineNav.test.ts
@@ -0,0 +1,55 @@
+import { describe, expect, it } from 'vitest'
+
+import { lineNav } from '../components/textInput.js'
+
+describe('lineNav', () => {
+  it('returns null for single-line input (up)', () => {
+    expect(lineNav('hello world', 6, -1)).toBeNull()
+  })
+
+  it('returns null for single-line input (down)', () => {
+    expect(lineNav('hello world', 6, 1)).toBeNull()
+  })
+
+  it('returns null when cursor already on first line of a multiline block', () => {
+    expect(lineNav('one\ntwo\nthree', 2, -1)).toBeNull()
+  })
+
+  it('returns null when cursor on last line of a multiline block', () => {
+    expect(lineNav('one\ntwo\nthree', 10, 1)).toBeNull()
+  })
+
+  it('moves cursor up one line preserving column', () => {
+    // "hello\nworld" — cursor at col 3 of line 1 ('l' in world) → col 3 of line 0 ('l' in hello)
+    expect(lineNav('hello\nworld', 9, -1)).toBe(3)
+  })
+
+  it('moves cursor down one line preserving column', () => {
+    // cursor at col 2 of line 0 → col 2 of line 1
+    expect(lineNav('hello\nworld', 2, 1)).toBe(8)
+  })
+
+  it('clamps to end of shorter destination line on up', () => {
+    // col 10 on long line → clamp to end of short line "abc"
+    const s = 'abc\nlong long text'
+    const from = 14
+
+    expect(lineNav(s, from, -1)).toBe(3)
+  })
+
+  it('clamps to end of shorter destination line on down', () => {
+    // col 10 on line 0 → clamp to end of "abc" on line 1
+    const s = 'long long text\nabc'
+
+    expect(lineNav(s, 10, 1)).toBe(18)
+  })
+
+  it('handles empty lines correctly', () => {
+    // "a\n\nb" — cursor at line 2 (b) → up to empty line 1
+    expect(lineNav('a\n\nb', 3, -1)).toBe(2)
+  })
+
+  it('handles leading newline without crashing', () => {
+    expect(lineNav('\nfoo', 2, -1)).toBe(0)
+  })
+})
diff --git a/ui-tui/src/components/textInput.tsx b/ui-tui/src/components/textInput.tsx
index 11c9bde76d..536f2f0181 100644
--- a/ui-tui/src/components/textInput.tsx
+++ b/ui-tui/src/components/textInput.tsx
@@ -134,6 +134,39 @@ function wordRight(s: string, p: number) {
   return i
 }
 
+/**
+ * Move cursor one logical line up or down inside `s` while preserving the
+ * column offset from the current line's start. Returns `null` when the cursor
+ * is already on the first line (up) or last line (down) — callers use that
+ * signal to fall through to history cycling instead of eating the arrow key.
+ */
+export function lineNav(s: string, p: number, dir: -1 | 1): null | number {
+  const pos = snapPos(s, p)
+  const curStart = s.lastIndexOf('\n', pos - 1) + 1
+  const col = pos - curStart
+
+  if (dir < 0) {
+    if (curStart === 0) {
+      return null
+    }
+
+    const prevStart = s.lastIndexOf('\n', curStart - 2) + 1
+
+    return snapPos(s, Math.min(prevStart + col, curStart - 1))
+  }
+
+  const nextBreak = s.indexOf('\n', pos)
+
+  if (nextBreak < 0) {
+    return null
+  }
+
+  const nextEnd = s.indexOf('\n', nextBreak + 1)
+  const lineEnd = nextEnd < 0 ? s.length : nextEnd
+
+  return snapPos(s, Math.min(nextBreak + 1 + col, lineEnd))
+}
+
 function cursorLayout(value: string, cursor: number, cols: number) {
   const pos = Math.max(0, Math.min(cursor, value.length))
   const w = Math.max(1, cols - 1)
@@ -570,9 +603,21 @@ export function TextInput({
         return
       }
 
+      if (k.upArrow || k.downArrow) {
+        const next = lineNav(vRef.current, curRef.current, k.upArrow ? -1 : 1)
+
+        if (next !== null) {
+          clearSel()
+          setCur(next)
+          curRef.current = next
+
+          return
+        }
+
+        return
+      }
+
       if (
-        k.upArrow ||
-        k.downArrow ||
         (k.ctrl && inp === 'c') ||
         k.tab ||
         (k.shift && k.tab) ||