fix(native-chat): keep a tab launch draft out of split sibling composers

src/renderer/src/components/native-chat/NativeChatComposer.tsx

@@ -72,8 +72,7 @@ export const NativeChatComposer = forwardRef<NativeChatComposerHandle, NativeCha
       onSlashCommand,
       onSwitchToTerminal,
       readTerminalScreen,
-      launchDraft,
-      launchDraftResolved = false,
+      launchSeed,
       structuredTransport
     },
     ref
@@ -88,8 +87,9 @@ export const NativeChatComposer = forwardRef<NativeChatComposerHandle, NativeCha
     useNativeChatLaunchDraftAdoption({
       terminalTabId,
       agent,
-      launchDraft,
-      launchDraftResolved,
+      launchDraft: launchSeed?.launchDraft,
+      launchDraftResolved: launchSeed?.launchDraftResolved === true,
+      ownsTabWideLaunchDraft: launchSeed?.ownsTabWideLaunchDraft === true,
       draft,
       setDraft,
       setCaret
@@ -285,8 +285,8 @@ export const NativeChatComposer = forwardRef<NativeChatComposerHandle, NativeCha
       imageAttachments,
       disabled,
       isDispatchingSessionOption,
-      launchDraft,
-      launchDraftResolved,
+      launchDraft: launchSeed?.launchDraft,
+      launchDraftResolved: launchSeed?.launchDraftResolved === true,
       readTerminalScreen,
       resolveTarget,
       classifySend,

src/renderer/src/components/native-chat/NativeChatView.tsx

@@ -73,6 +73,7 @@
   targetPtyId = null,
   launchAgent,
   resolvedAgent,
+  ownsTabWideLaunchDraft,
   onSwitchToTerminal,
   readTerminalScreen,
   contextMenuActions,
@@ -99,6 +100,7 @@
           isVisible={isVisible}
           targetPtyId={targetPtyId}
           terminalTabId={terminalTabId}
+          ownsTabWideLaunchDraft={ownsTabWideLaunchDraft}
           onSwitchToTerminal={onSwitchToTerminal}
           readTerminalScreen={readTerminalScreen}
           contextMenuActions={contextMenuActions}
@@ -117,6 +119,7 @@
   isVisible,
   targetPtyId,
   terminalTabId,
+  ownsTabWideLaunchDraft,
   onSwitchToTerminal,
   readTerminalScreen,
   contextMenuActions,
@@ -140,7 +143,6 @@
   const paneLaunchPrompt = launchPrompt?.agent === agent ? launchPrompt : null
   // Launch context prefilled into the TUI input as an unsent draft; the
   // composer adopts it so the GUI view shows the same context as the TUI.
-  // Shape matches NativeChatComposer's two launch-draft props, so it spreads.
   const launchDraftSignal = useNativeChatLaunchDraftSignal({
     terminalTabId,
     agent,
@@ -450,10 +452,10 @@
           onSlashCommand={onSlashCommand}
           onSwitchToTerminal={onSwitchToTerminal}
           readTerminalScreen={readTerminalScreen}
-          {...launchDraftSignal}
+          launchSeed={{ ...launchDraftSignal, ownsTabWideLaunchDraft }}
         />
       )}
       {contextMenu.menu}
     </div>
   )
 }

src/renderer/src/components/native-chat/native-chat-composer-types.ts

@@ -47,14 +47,22 @@ export type NativeChatComposerProps = {
   onSwitchToTerminal?: () => void
   /** Reads the hosted TUI's current rendered screen when chat is entered. */
   readTerminalScreen?: () => string | null
-  /** Launch context prefilled into the TUI input as an unsent draft; adopted as the composer draft. */
-  launchDraft?: NativeChatLaunchDraft | null
-  /** True once the transcript shows the TUI-side draft was submitted or cleared. */
-  launchDraftResolved?: boolean
+  /** The tab's launch seed as this pane sees it. */
+  launchSeed?: NativeChatLaunchSeed
   /** Structured journal transport; absent keeps the existing PTY path unchanged. */
   structuredTransport?: NativeChatStructuredComposerTransport
 }
 
+/** Launch context prefilled into the TUI input as an unsent draft, plus the two
+ *  facts that decide its fate in this pane's composer. */
+export type NativeChatLaunchSeed = {
+  launchDraft: NativeChatLaunchDraft | null
+  /** True once the transcript shows the TUI-side draft was submitted or cleared. */
+  launchDraftResolved: boolean
+  /** False for every pane of a split tab; gates adopting the seed, not cleanup. */
+  ownsTabWideLaunchDraft: boolean
+}
+
 export type NativeChatComposerHandle = {
   focus: () => boolean
   insertTypedText: (text: string) => boolean

src/renderer/src/components/native-chat/native-chat-leaf-routing.test.ts

@@ -1,9 +1,45 @@
 import { describe, expect, it } from 'vitest'
 import {
   nativeChatLaunchAgentForLeaf,
+  nativeChatLeafOwnsTabWideEvidence,
   resolveNativeChatLeafRoute
 } from './native-chat-leaf-routing'
 
+describe('nativeChatLeafOwnsTabWideEvidence', () => {
+  it("owns tab-wide evidence only while the bound leaf is still the tab's sole pane", () => {
+    expect(
+      nativeChatLeafOwnsTabWideEvidence({
+        ownerLeafId: 'leaf-a',
+        leafId: 'leaf-a',
+        leafIds: ['leaf-a']
+      })
+    ).toBe(true)
+    // A split sibling must not inherit the tab's launch draft (issue #16695).
+    expect(
+      nativeChatLeafOwnsTabWideEvidence({
+        ownerLeafId: 'leaf-a',
+        leafId: 'leaf-b',
+        leafIds: ['leaf-a', 'leaf-b']
+      })
+    ).toBe(false)
+    // Not even the original pane keeps it once the tab is split.
+    expect(
+      nativeChatLeafOwnsTabWideEvidence({
+        ownerLeafId: 'leaf-a',
+        leafId: 'leaf-a',
+        leafIds: ['leaf-a', 'leaf-b']
+      })
+    ).toBe(false)
+    expect(
+      nativeChatLeafOwnsTabWideEvidence({
+        ownerLeafId: null,
+        leafId: 'leaf-a',
+        leafIds: ['leaf-a']
+      })
+    ).toBe(false)
+  })
+})
+
 describe('nativeChatLaunchAgentForLeaf', () => {
   it('uses the tab launch hint only for its sole leaf', () => {
     expect(

src/renderer/src/components/native-chat/native-chat-leaf-routing.ts

@@ -44,19 +44,37 @@ export function isNativeChatTabWideFallbackSafe(
   return !layout.activeLeafId || layout.activeLeafId === layout.root.leafId
 }
 
+/** Whether tab-wide launch evidence (agent hint, launch draft) describes this
+ *  leaf: it must still be the tab's sole pane and the one the evidence bound to. */
+export function nativeChatLeafOwnsTabWideEvidence(args: {
+  ownerLeafId: string | null
+  leafId: string | null
+  leafIds: readonly string[]
+}): boolean {
+  const { ownerLeafId, leafId, leafIds } = args
+  if (!ownerLeafId || !leafId) {
+    return false
+  }
+  // Why: the evidence belongs to the tab's original pane. Once a split exists,
+  // it says nothing about any particular sibling.
+  return leafIds.length === 1 && leafIds[0] === leafId && ownerLeafId === leafId
+}
+
 export function nativeChatLaunchAgentForLeaf(args: {
   launchAgent?: TuiAgent | null
   launchAgentLeafId: string | null
   leafId: string | null
   leafIds: readonly string[]
 }): TuiAgent | null {
   const { launchAgent, launchAgentLeafId, leafId, leafIds } = args
-  if (!launchAgent || !launchAgentLeafId || !leafId) {
+  if (!launchAgent) {
     return null
   }
-  // Why: launchAgent belongs to the tab's original pane. Once a split exists,
-  // it is not evidence that an agent is running in any particular sibling.
-  return leafIds.length === 1 && leafIds[0] === leafId && launchAgentLeafId === leafId
+  return nativeChatLeafOwnsTabWideEvidence({
+    ownerLeafId: launchAgentLeafId,
+    leafId,
+    leafIds
+  })
     ? launchAgent
     : null
 }

src/renderer/src/components/native-chat/native-chat-view-types.ts

@@ -25,6 +25,8 @@ export type NativeChatBridgeViewProps = NativeChatOrchestrationProps & {
   launchAgent?: TuiAgent | null
   /** Trusted title/foreground fallback for manually-started agents. */
   resolvedAgent?: TuiAgent | null
+  /** Whether this pane owns the tab's launch draft; false for split siblings. */
+  ownsTabWideLaunchDraft: boolean
   /** Return this pane to the hosted terminal surface. */
   onSwitchToTerminal?: () => void
   /** Current xterm screen reader used to recover agent-reported session state. */
@@ -50,6 +52,7 @@ export type NativeChatResolvedViewProps = NativeChatOrchestrationProps & {
   isVisible: boolean
   targetPtyId: string | null
   terminalTabId: string
+  ownsTabWideLaunchDraft: boolean
   onSwitchToTerminal?: () => void
   readTerminalScreen?: () => string | null
   contextMenuActions?: Omit<NativeChatContextMenuActions, 'onPaste'>

src/renderer/src/components/native-chat/use-native-chat-launch-draft-adoption.test.tsx

@@ -29,11 +29,13 @@ vi.mock('../../store', () => {
   return { useAppStore }
 })
 
+const SEED_TEXT = 'https://github.com/o/r/issues/12'
+
 function launchDraft(overrides: Partial<NativeChatLaunchDraft> = {}): NativeChatLaunchDraft {
   return {
     tabId: 'tab-1',
     agent: 'claude',
-    text: 'https://github.com/o/r/issues/12',
+    text: SEED_TEXT,
     createdAt: 1000,
     ...overrides
   }
@@ -44,6 +46,7 @@ function setup(args: {
   launchDraftResolved?: boolean
   draft?: string
   agent?: string
+  ownsTabWideLaunchDraft?: boolean
 }): { setDraft: ReturnType<typeof vi.fn>; setCaret: ReturnType<typeof vi.fn> } {
   const setDraft = vi.fn()
   const setCaret = vi.fn()
@@ -55,7 +58,8 @@ function setup(args: {
       launchDraftResolved: args.launchDraftResolved ?? false,
       draft: args.draft ?? '',
       setDraft,
-      setCaret
+      setCaret,
+      ownsTabWideLaunchDraft: args.ownsTabWideLaunchDraft ?? true
     })
   )
   return { setDraft, setCaret }
@@ -67,7 +71,10 @@ function userTurn(id: string, timestamp: number | null): NativeChatMessage {
   return { id, role: 'user', blocks: [{ type: 'text', text: id }], timestamp, source: 'transcript' }
 }
 
-type SignalProps = { messages: NativeChatMessage[]; transcriptLoading?: boolean }
+type SignalProps = {
+  messages: NativeChatMessage[]
+  transcriptLoading?: boolean
+}
 
 function renderSignal(messages: NativeChatMessage[], transcriptLoading = false) {
   const initialProps: SignalProps = { messages, transcriptLoading }
@@ -186,6 +193,14 @@ describe('useNativeChatLaunchDraftSignal', () => {
     expect(result.current.launchDraft?.resolved).toBe(true)
   })
 
+  it("selects the tab's seed for every pane so the resolution machine keeps running", () => {
+    // Pane ownership gates the composer *write*, not the signal: nulling it here
+    // would also kill the resolved/cleanup branch for a split tab.
+    const { result } = renderSignal([])
+
+    expect(result.current.launchDraft?.text).toBe(SEED_TEXT)
+  })
+
   it('ignores a draft seeded for another agent', () => {
     mocks.storeState.nativeChatLaunchDraftByTabId = {
       'tab-1': launchDraft({ agent: 'codex', createdAt: SEEDED_AT })
@@ -258,6 +273,21 @@ describe('useNativeChatLaunchDraftAdoption', () => {
     expect(mocks.clearNativeChatLaunchDraft).toHaveBeenCalledWith('tab-1')
   })
 
+  it('does not mirror the seed into a pane that does not own the tab-wide evidence', () => {
+    const { setDraft } = setup({ launchDraft: launchDraft(), ownsTabWideLaunchDraft: false })
+
+    expect(setDraft).not.toHaveBeenCalled()
+    expect(mocks.markNativeChatLaunchDraftAdopted).not.toHaveBeenCalled()
+  })
+
+  it('leaves an unadopted seed alone when a non-owning pane resolves it', () => {
+    // The owner may not have mirrored it yet; a sibling's transcript is no
+    // evidence about the owner's copy.
+    setup({ launchDraft: launchDraft(), launchDraftResolved: true, ownsTabWideLaunchDraft: false })
+
+    expect(mocks.clearNativeChatLaunchDraft).not.toHaveBeenCalled()
+  })
+
   it('drops an unadopted seed once the transcript resolves it', () => {
     const { setDraft } = setup({ launchDraft: launchDraft(), launchDraftResolved: true })
 
@@ -266,3 +296,82 @@ describe('useNativeChatLaunchDraftAdoption', () => {
     expect(mocks.clearNativeChatLaunchDraft).toHaveBeenCalledWith('tab-1')
   })
 })
+
+describe('launch draft adoption across a split', () => {
+  beforeEach(() => {
+    vi.clearAllMocks()
+    mocks.storeState.nativeChatLaunchDraftByTabId = {
+      'tab-1': launchDraft({ createdAt: SEEDED_AT })
+    }
+  })
+
+  function renderPaneComposer(args: {
+    ownsTabWideLaunchDraft: boolean
+    draft?: string
+    messages?: NativeChatMessage[]
+  }): { setDraft: ReturnType<typeof vi.fn>; setCaret: ReturnType<typeof vi.fn> } {
+    const setDraft = vi.fn()
+    const setCaret = vi.fn()
+    renderHook(() => {
+      const signal = useNativeChatLaunchDraftSignal({
+        terminalTabId: 'tab-1',
+        agent: 'claude',
+        messages: args.messages ?? [],
+        transcriptLoading: false
+      })
+      useNativeChatLaunchDraftAdoption({
+        terminalTabId: 'tab-1',
+        agent: 'claude',
+        launchDraft: signal.launchDraft,
+        launchDraftResolved: signal.launchDraftResolved,
+        draft: args.draft ?? '',
+        setDraft,
+        setCaret,
+        ownsTabWideLaunchDraft: args.ownsTabWideLaunchDraft
+      })
+    })
+    return { setDraft, setCaret }
+  }
+
+  it("never fills a non-owning pane's composer with the tab's launch draft", () => {
+    const { setDraft } = renderPaneComposer({ ownsTabWideLaunchDraft: false })
+
+    expect(setDraft).not.toHaveBeenCalled()
+    expect(mocks.markNativeChatLaunchDraftAdopted).not.toHaveBeenCalled()
+  })
+
+  it('never lets a non-owning pane destroy a seed nobody has adopted yet', () => {
+    const { setDraft } = renderPaneComposer({
+      ownsTabWideLaunchDraft: false,
+      messages: [userTurn('u1', null)]
+    })
+
+    expect(setDraft).not.toHaveBeenCalled()
+    expect(mocks.clearNativeChatLaunchDraft).not.toHaveBeenCalled()
+  })
+
+  it('still mirrors the launch draft into the owning pane composer', () => {
+    const { setDraft } = renderPaneComposer({ ownsTabWideLaunchDraft: true })
+
+    expect(setDraft).toHaveBeenCalledWith(SEED_TEXT)
+  })
+
+  it('clears the adopted copy after a split once the transcript resolves the seed', () => {
+    // Splitting drops ownership for *both* panes, so the pane that already
+    // mirrored the seed must still clean up — otherwise the submitted prompt
+    // sits in its composer forever and a later Enter re-sends it (#16695).
+    mocks.storeState.nativeChatLaunchDraftByTabId = {
+      'tab-1': launchDraft({ adopted: true, createdAt: SEEDED_AT })
+    }
+
+    const { setDraft, setCaret } = renderPaneComposer({
+      ownsTabWideLaunchDraft: false,
+      draft: SEED_TEXT,
+      messages: [userTurn('u1', null)]
+    })
+
+    expect(setDraft).toHaveBeenCalledWith('')
+    expect(setCaret).toHaveBeenCalledWith(0)
+    expect(mocks.clearNativeChatLaunchDraft).toHaveBeenCalledWith('tab-1')
+  })
+})