fix(native-chat): clear launch drafts from any cursor

src/renderer/src/components/native-chat/native-chat-launch-draft-send.test.ts

@@ -85,6 +85,16 @@ describe('agentInputLineCleared', () => {
     expect(agentInputLineCleared(edited)).toBe(false)
   })
 
+  it('does not ignore nonempty continuation rows after an empty prompt row', () => {
+    const residue = [
+      '────────────────────────────────────────',
+      '❯ ',
+      '  suffix after a cursor-middle clear',
+      '────────────────────────────────────────'
+    ].join('\n')
+    expect(agentInputLineCleared(residue)).toBe(false)
+  })
+
   it('treats placeholders and parked drafts as unconfirmed', () => {
     expect(agentInputLineCleared(screenPlaceholder)).toBe(false)
     expect(agentInputLineCleared(screenHoldingDraft)).toBe(false)

src/renderer/src/components/native-chat/native-chat-launch-draft-send.ts

@@ -11,7 +11,25 @@ export type NativeChatLaunchDraftSendPlan =
   | { kind: 'default' }
 
 /** Prompt glyphs both supported agent TUIs draw at the start of the input line. */
-const COMPOSER_PROMPT_LINE = /^\s*[❯›]\s?(.*)$/
+const COMPOSER_PROMPT_LINE = /^\s*([❯›])\s?(.*)$/
+const CLAUDE_FRAME_LINE = /^\s*─{3,}\s*$/
+const CODEX_FOOTER_LINE = /^\s*\S.*\s[·•]\s.*$/
+
+function composerContinuationIsEmpty(lines: string[], promptIndex: number, glyph: string): boolean {
+  for (let index = promptIndex + 1; index < lines.length; index += 1) {
+    const line = lines[index]!
+    if (
+      (glyph === '❯' && CLAUDE_FRAME_LINE.test(line)) ||
+      (glyph === '›' && CODEX_FOOTER_LINE.test(line))
+    ) {
+      return true
+    }
+    if (line.trim() !== '') {
+      return false
+    }
+  }
+  return true
+}
 
 /**
  * Whether the rendered composer prompt is observably empty. Placeholder text,
@@ -25,7 +43,7 @@ export function agentInputLineCleared(screen: string | null | undefined): boolea
   for (let index = lines.length - 1; index >= 0; index -= 1) {
     const match = COMPOSER_PROMPT_LINE.exec(lines[index]!)
     if (match) {
-      return match[1]!.trim() === ''
+      return match[2]!.trim() === '' && composerContinuationIsEmpty(lines, index, match[1]!)
     }
   }
   return false

src/renderer/src/lib/native-chat-launch-draft-mirrorability.test.ts

@@ -13,6 +13,10 @@ vi.mock('@/store', () => ({
 import { seedNativeChatLaunchDraftForAgentTab } from './agent-launch-prompt-delivery'
 import { canMirrorLaunchDraftToNativeChat } from './native-chat-launch-draft-mirrorability'
 import { decideInitialAgentTabViewMode } from './native-chat-initial-view-mode'
+import { AGENT_TUI_CLEAR_MAX_LINES } from '../../../shared/agent-tui-input-clear'
+
+const maxLineDraft = Array.from({ length: AGENT_TUI_CLEAR_MAX_LINES }, () => 'line').join('\n')
+const overMaxLineDraft = `${maxLineDraft}\nline`
 
 /**
  * Every shape a launch draft takes today. `formatDraftContextBlock` appends a
@@ -28,6 +32,8 @@ const DRAFT_TEXTS = [
   'ORC-123: Restore linked quick-create\nhttps://linear.app/o/issue/ORC-123',
   'ORC-123 https://linear.app/o/issue/ORC-123\n',
   '  spaced but single line  ',
+  maxLineDraft,
+  overMaxLineDraft,
   '',
   '   ',
   '\n'
@@ -79,6 +85,11 @@ describe('launch draft mirrorability', () => {
     expect(canMirrorLaunchDraftToNativeChat('   ')).toBe(false)
   })
 
+  it('rejects drafts beyond the bounded TUI-clear budget', () => {
+    expect(canMirrorLaunchDraftToNativeChat(maxLineDraft)).toBe(true)
+    expect(canMirrorLaunchDraftToNativeChat(overMaxLineDraft)).toBe(false)
+  })
+
   it('withholds the mirror from agents without a native-chat renderer', () => {
     // The view mode already returns undefined for these, so the sets still
     // agree — but only the seeding side enforces it.

src/renderer/src/lib/native-chat-launch-draft-mirrorability.ts

@@ -1,3 +1,8 @@
+import {
+  AGENT_TUI_CLEAR_MAX_LINES,
+  countAgentTuiInputLines
+} from '../../../shared/agent-tui-input-clear'
+
 /**
  * Single source of truth for whether unsent launch context can be mirrored from
  * the agent's TUI input into the native-chat composer.
@@ -7,9 +12,13 @@
  * predicate, so a draft launch can never open in chat with a composer that
  * chat then refuses to fill.
  *
- * CR/LF drafts are safe because chat sizes its TUI pre-clear from their logical
- * line count. Unicode line separators remain unsupported by that clear contract.
+ * CR/LF drafts are safe within the bounded TUI-clear budget. Unicode line
+ * separators and drafts beyond that budget remain terminal-only.
  */
 export function canMirrorLaunchDraftToNativeChat(text: string): boolean {
-  return text.trim().length > 0 && !/[\u2028\u2029]/.test(text)
+  return (
+    text.trim().length > 0 &&
+    !/[\u2028\u2029]/.test(text) &&
+    countAgentTuiInputLines(text) <= AGENT_TUI_CLEAR_MAX_LINES
+  )
 }

src/shared/agent-tui-input-clear.test.ts

@@ -1,5 +1,6 @@
 import { describe, expect, it } from 'vitest'
 import {
+  AGENT_TUI_CLEAR_INPUT_FORWARD,
   AGENT_TUI_CLEAR_INPUT_LINE,
   AGENT_TUI_CLEAR_INPUT_MAX,
   AGENT_TUI_CLEAR_LINE_SLACK,
@@ -11,6 +12,8 @@ import {
 
 const countCtrlU = (bytes: string): number =>
   bytes.split('').filter((char) => char === AGENT_TUI_CLEAR_INPUT_LINE).length
+const countCtrlK = (bytes: string): number =>
+  bytes.split('').filter((char) => char === AGENT_TUI_CLEAR_INPUT_FORWARD).length
 
 describe('buildAgentTuiClearInput', () => {
   // The measured law: N kills + (N-1) joins. A constant here silently under-clears
@@ -23,11 +26,15 @@ describe('buildAgentTuiClearInput', () => {
     [4, 7],
     [10, 19]
   ])('clears %i logical lines with %i Ctrl+U', (lines, expected) => {
-    expect(countCtrlU(buildAgentTuiClearInput(lines))).toBe(expected)
+    const clearInput = buildAgentTuiClearInput(lines)
+    expect(countCtrlU(clearInput)).toBe(expected)
+    expect(countCtrlK(clearInput)).toBe(expected)
   })
 
-  it('emits nothing but Ctrl+U — Ctrl+A/Ctrl+K do not clear a multi-line buffer', () => {
-    expect(buildAgentTuiClearInput(4)).toBe(AGENT_TUI_CLEAR_INPUT_LINE.repeat(7))
+  it('clears before the cursor before clearing the suffix after it', () => {
+    expect(buildAgentTuiClearInput(4)).toBe(
+      AGENT_TUI_CLEAR_INPUT_LINE.repeat(7) + AGENT_TUI_CLEAR_INPUT_FORWARD.repeat(7)
+    )
   })
 
   it('still clears one line for a zero or negative count', () => {

src/shared/agent-tui-input-clear.ts

@@ -3,34 +3,20 @@
 // Shared by desktop native chat and mobile: the law below is a property of the
 // agent TUIs (Claude Code, codex), not of either client.
 
-/** Ctrl+U — kills to the START OF THE CURRENT LOGICAL LINE in an agent TUI. */
+/** Ctrl+U — clears toward the start of the input buffer. */
 export const AGENT_TUI_CLEAR_INPUT_LINE = '\x15'
 
-/**
- * How many Ctrl+U an N-line buffer costs: **2N-1**.
- *
- * Measured on real PTYs against Claude Code and codex; both agree exactly. Each
- * Ctrl+U kills to the start of the current logical line; when that line is
- * ALREADY EMPTY the next one deletes the newline and joins to the previous line.
- * So N kills + (N-1) joins = 2N-1. (N=2 needs 3; N=4 with 5 leaves residue;
- * N=4 with 7 is clean.)
- *
- * Rejected alternatives — all measured, do not "fix" this by reaching for them:
- * - **Ctrl+A, Ctrl+K, Ctrl+U** (the sequence a comparable agent-TUI wrapper uses)
- *   does NOT clear a multi-line buffer. Ctrl+A/Ctrl+K act inside the CURRENT
- *   logical line only, so earlier lines survive AND the cursor is left at the end
- *   of the previous line — the next paste glues straight onto it, strictly worse
- *   than a single Ctrl+U.
- * - **Esc** does nothing at all to the buffer in either TUI.
- * - **A fixed repeat count** is silently wrong: 5 clears 3 lines but leaves
- *   residue at 4. The count must come from the line count.
- *
- * Only LOGICAL newlines cost anything: one 300-char line wrapping several visual
- * rows still dies to a single Ctrl+U, so callers must not count wrapped rows.
- */
+/** Ctrl+K — clears toward the end of the input buffer. */
+export const AGENT_TUI_CLEAR_INPUT_FORWARD = '\x0b'
+
+/** Clear up to `lineCount` logical lines from any cursor position. */
 export function buildAgentTuiClearInput(lineCount: number): string {
   const lines = Math.max(1, Math.min(AGENT_TUI_CLEAR_MAX_LINES, Math.floor(lineCount)))
-  return AGENT_TUI_CLEAR_INPUT_LINE.repeat(2 * lines - 1)
+  const repetitions = 2 * lines - 1
+  return (
+    AGENT_TUI_CLEAR_INPUT_LINE.repeat(repetitions) +
+    AGENT_TUI_CLEAR_INPUT_FORWARD.repeat(repetitions)
+  )
 }
 
 /**