fix(launch-prompt): on Windows, paste what the line can't carry where main pasted it

Main pastes an AI button's or notes send's prompt once the agent runs, so the
agent's history, /resume, the chat view and AI Vault show the user's text. A
launch file replaced nearly every such prompt on Windows with a pointer.

The caller's paste is now one of 'never', 'when-host-proves-agent' (#24257's
guarded paste) or 'once-agent-runs' (main's desktop paste for submit-after-ready
prompts). On Windows a prompt the line cannot carry exactly goes to an
'once-agent-runs' paste first; a launch file is left for the lines main would
have typed damaged or too long. Temporary, until the agent's own argv carries
multi-line text past cmd without a shim re-parsing it.

src/main/runtime/orca-runtime-create-agent-session.ts

@@ -189,7 +189,7 @@ export class OrcaRuntimeWithCreateAgentSession extends OrcaRuntimeWithGetAgentSe
             isRemote: Boolean(workspace.connectionId)
           }),
           // Why: this create returns before the agent is ready, so nothing pastes after it.
-          canPasteAfterReady: false
+          paste: 'never'
         })
         if (!planned) {
           throw new Error('agent_session_identity_required')

src/main/runtime/orca-runtime-resolve-mobile-session-terminal-command.ts

@@ -63,7 +63,7 @@ export class OrcaRuntimeWithResolveMobileSessionTerminalCommand extends OrcaRunt
       prompt: opts.agentPrompt ?? '',
       host: thisOrcaLaunchHost({ launchPlatform, isRemote }),
       // Why: a quick command has no paste after ready.
-      canPasteAfterReady: false
+      paste: 'never'
     })
     if (!planned) {
       throw new Error(`Could not build launch command for ${opts.agent}.`)

src/main/runtime/orca-runtime-resolve-worktree-removal-target.ts

@@ -272,7 +272,7 @@ export class OrcaRuntimeWithResolveWorktreeRemovalTarget extends OrcaRuntimeWith
       prompt: opts.startupPrompt ?? '',
       ...(opts.launchFile ? { launchFile: opts.launchFile } : {}),
       host: thisOrcaLaunchHost({ launchPlatform: platform, isRemote }),
-      canPasteAfterReady: opts.onStartupPromptCarry !== undefined
+      paste: opts.onStartupPromptCarry ? 'when-host-proves-agent' : 'never'
     })
     if (!planned) {
       // Why: an explicit agent that yields no plan would otherwise spawn a bare

src/main/runtime/runtime-worktree-agent-startup.ts

@@ -162,8 +162,8 @@ export function buildWorktreeStartupForAgent(
       isRemote: repoIsRemote(repo),
       launchPlatform: environment.getLaunchPlatform()
     }),
-    // A caller that cannot paste takes a follow-up and sends it once the agent is ready.
-    canPasteAfterReady: true
+    // The caller, or else the host's follow-up, pastes what the line leaves once the agent runs.
+    paste: 'when-host-proves-agent'
   })
   if (!planned) {
     throw new Error(`Could not build launch command for ${agent}.`)

src/renderer/src/components/sidebar/folder-workspace-composer-submit.ts

@@ -134,7 +134,7 @@ export async function submitFolderWorkspaceCreate({
                 launchPlatform,
                 isRemote: launchIsRemote
               }),
-              canPasteAfterReady: true
+              paste: 'when-host-proves-agent'
             }),
             note
           )

src/renderer/src/hooks/composer-state/full-creation-startup.test.ts

@@ -17,7 +17,7 @@ describe('the full composer’s renderer-spawned startup', () => {
         platform: 'linux',
         isRemote: true,
         host: { paired: false, provesAgentInFront: true },
-        canPasteAfterReady: true
+        paste: 'when-host-proves-agent'
       }),
       prompt
     )

src/renderer/src/hooks/composer-state/full-submit-preparation.ts

@@ -210,7 +210,7 @@ export function useFullSubmitPreparation(input: FullSubmitPreparationInput) {
             launchPlatform: selectedRepoAgentLaunchPlatform,
             isRemote: selectedRepoIsRemote
           }),
-          canPasteAfterReady: true
+          paste: 'when-host-proves-agent'
         }),
         submitStartupPrompt
       )

src/renderer/src/hooks/composer-state/quick-startup-plan.ts

@@ -98,7 +98,7 @@ export function buildQuickComposerStartup(input: QuickComposerStartupInput): Qui
         shell: input.shell ?? undefined,
         isRemote: input.isRemote,
         host: input.host,
-        canPasteAfterReady: true
+        paste: 'when-host-proves-agent'
       }),
       prompt
     )

src/renderer/src/lib/launch-agent-background-session.ts

@@ -89,7 +89,7 @@ export async function launchAgentBackgroundSession(
       launchPlatform,
       isRemote
     }),
-    canPasteAfterReady: true
+    paste: 'when-host-proves-agent'
   })
   if (!planned) {
     return null

src/renderer/src/lib/launch-agent-in-new-tab-windows-quoting.test.ts

@@ -181,6 +181,26 @@ describe('launchAgentInNewTab Windows shell quoting', () => {
     expect(mockCreateWebRuntimeAgentSessionTerminalWithLaunchDraft).not.toHaveBeenCalled()
   })
 
+  it('pastes a multi-line AI-button prompt on Windows, as main did, instead of a launch file', async () => {
+    const { launchAgentInNewTab } = await import('./launch-agent-in-new-tab')
+    const prompt = 'Fix the failing checks.\nThen push.'
+
+    launchAgentInNewTab({
+      agent: 'codex',
+      worktreeId: 'wt-1',
+      prompt,
+      promptDelivery: 'submit-after-ready',
+      launchPlatform: 'win32'
+    })
+
+    const queued = mockQueueTabStartupCommand.mock.calls[0]?.[1]
+    expect(queued?.launchFile).toBeUndefined()
+    expect(queued?.command).not.toContain('Fix the failing checks')
+    expect(mockPasteDraftWhenAgentReady).toHaveBeenCalledWith(
+      expect.objectContaining({ tabId: 'tab-1', content: prompt, agent: 'codex', submit: true })
+    )
+  })
+
   it('uses the explicit startup shell platform when building draft launch commands', async () => {
     const { launchAgentInNewTab } = await import('./launch-agent-in-new-tab')
 

src/renderer/src/lib/launch-agent-startup-prompt-plan.ts

@@ -72,7 +72,13 @@ export function planLaunchAgentStartupPrompt(args: {
   if (prompt.length > 0 && args.host.paired && promptDelivery === 'submit-after-ready') {
     return pasteAfterReady(cleanPlan(), prompt, true)
   }
-  const planned = planLaunchPrompt({ ...base, prompt, host: args.host, canPasteAfterReady: true })
+  const planned = planLaunchPrompt({
+    ...base,
+    prompt,
+    host: args.host,
+    // Why: main pastes a submit-after-ready prompt once the agent runs and types the rest.
+    paste: promptDelivery === 'submit-after-ready' ? 'once-agent-runs' : 'when-host-proves-agent'
+  })
   if (!planned) {
     return { startupPlan: null, pasteDraftAfterLaunch: null, submitPastedPrompt: false }
   }

src/renderer/src/lib/launch-work-item-direct-agent.ts

@@ -83,7 +83,7 @@ export function buildDirectWorkItemAgentStartupPlan(args: {
       ...planInputs,
       prompt: args.draftContent,
       host: args.host,
-      canPasteAfterReady: true
+      paste: 'once-agent-runs'
     })
     if (!planned) {
       return { startupPlan: null, promptOnLaunchCommand: false, startupPlanFailed: true }

src/renderer/src/lib/source-control-agent-action-plan.test.ts

@@ -55,6 +55,26 @@ describe('planSourceControlAgentActionLaunch', () => {
     expect(result.ok && result.summary).not.toContain('included in the launch command')
   })
 
+  // Why: main pastes an AI button's prompt on Windows, so the agent's history shows the user's
+  // text; only a typed prompt the line would damage rides a launch file.
+  it('pastes a multi-line AI-button prompt on Windows, and files the same prompt typed', () => {
+    const plan = (promptDelivery: 'submit-after-ready' | 'auto-submit') =>
+      planSourceControlAgentActionLaunch({
+        agent: 'claude',
+        commandInput: 'Fix the failing checks.\nThen push.',
+        promptDelivery,
+        detectedAgents: ['claude'],
+        platform: 'win32',
+        terminalWindowsShell: 'cmd.exe'
+      })
+
+    const button = plan('submit-after-ready')
+    expect(button.ok && button.delivery).toBe('paste-submit')
+    expect(button.ok && button.plan.launchCommand).not.toContain('task-context')
+    const typed = plan('auto-submit')
+    expect(typed.ok && typed.summary).toContain('private file')
+  })
+
   it('includes per-action CLI arguments in submit-after-ready launch plans', () => {
     const result = planSourceControlAgentActionLaunch({
       agent: 'codex',

src/renderer/src/lib/source-control-agent-action-plan.ts

@@ -160,7 +160,8 @@ export function planSourceControlAgentActionLaunch(args: {
         launchPlatform: platform,
         isRemote
       }),
-      canPasteAfterReady: true
+      paste:
+        args.promptDelivery === 'submit-after-ready' ? 'once-agent-runs' : 'when-host-proves-agent'
     })
     switch (planned?.carry) {
       case undefined:

src/shared/launch-host.ts

@@ -4,7 +4,7 @@ export type LaunchHost = {
    *  stage nor accompany with a launch file. Temporary, until paired hosts advertise both. */
   paired: boolean
   /** Whether the host can prove the launched agent holds its terminal before a paste
-   *  (`launched-agent-foreground`). A Windows host cannot, so it refuses a paste. */
+   *  (`launched-agent-foreground`). A Windows host cannot, so #24257's guarded paste is refused. */
   provesAgentInFront: boolean
 }
 

src/shared/launch-prompt-carry.test.ts

@@ -14,7 +14,7 @@ function plan(
   extra: Partial<Omit<AgentLaunchPromptArgs, 'agent' | 'prompt'>> = {}
 ) {
   const platform = extra.platform ?? 'darwin'
-  // A local launch on that platform, by a caller that pastes, unless the test says otherwise.
+  // A local launch on that platform, with #24257's guarded paste, unless the test says otherwise.
   const host = describeLaunchHost({
     launchPlatform: platform,
     isRemote: false,
@@ -27,7 +27,7 @@ function plan(
     cmdOverrides: {},
     platform,
     host,
-    canPasteAfterReady: true,
+    paste: 'when-host-proves-agent',
     ...extra
   })
 }
@@ -84,7 +84,7 @@ describe('where a launch prompt rides', () => {
   // (agentSession.create, a phone quick command) must not refuse it now.
   it('keeps a file-sized prompt on the line for a caller that cannot paste', () => {
     const prompt = 'g'.repeat(MAX_INLINE_LAUNCH_PROMPT_CHARS + 1)
-    const planned = plan('gemini', prompt, { canPasteAfterReady: false })
+    const planned = plan('gemini', prompt, { paste: 'never' })
     expect(planned?.carry).toBe('on-line')
     expect(planned?.carry === 'on-line' && planned.plan.launchCommand).toContain('gggg')
   })
@@ -140,6 +140,40 @@ describe('a host that types the line raw', () => {
     expect(plan('gemini', prompt, { platform: 'win32', shell: 'cmd' })?.carry).toBe('on-line')
   })
 
+  // Why: main pastes an AI button's or notes send's prompt once the agent runs, so the agent's
+  // history shows the user's text; a pointer replaces only a line main would type damaged.
+  it.each<TuiAgent>(['claude', 'codex'])(
+    'pastes what a Windows line cannot carry for a caller whose paste main used, for %s',
+    (agent) => {
+      const paste = 'once-agent-runs' as const
+      const multiLine = 'fix the build\nthen run the tests'
+      const pasted = plan(agent, multiLine, { platform: 'win32', shell: 'cmd', paste })
+      expect(pasted).toMatchObject({ carry: 'paste-after-ready', text: multiLine })
+      const long = 'y'.repeat(20_000)
+      expect(plan(agent, long, { platform: 'win32', shell: 'cmd', paste })?.carry).toBe(
+        'paste-after-ready'
+      )
+      expect(plan(agent, 'fix it', { platform: 'win32', shell: 'cmd', paste })?.carry).toBe(
+        'on-line'
+      )
+      const typed = plan(agent, multiLine, { platform: 'win32', shell: 'cmd' })
+      expect(typed?.carry).toBe('launch-file')
+    }
+  )
+
+  it('pastes a Windows-damaged prompt for any agent when the caller’s paste is main’s', () => {
+    const extra = { platform: 'win32' as const, shell: 'powershell' as const }
+    expect(plan('gemini', 'say "hi"', { ...extra, paste: 'once-agent-runs' })?.carry).toBe(
+      'paste-after-ready'
+    )
+    expect(plan('gemini', 'say "hi"', extra)?.carry).toBe('on-line')
+  })
+
+  it('still points Claude at a file past the argv ceiling on a POSIX host, whatever the paste', () => {
+    const planned = plan('claude', 'y'.repeat(20_000), { paste: 'once-agent-runs' })
+    expect(planned?.carry).toBe('launch-file')
+  })
+
   // Why: a host that cannot prove the agent holds its terminal refuses a paste (#24257), so the
   // line carries what the paste would have, as main typed it; Claude and Codex still get the file.
   it('keeps a prompt on the line of a host that cannot paste, unless a file can carry it', () => {
@@ -153,6 +187,9 @@ describe('a host that types the line raw', () => {
     expect(plan('gemini', 'y'.repeat(20_000), extra)?.carry).toBe('on-line')
     expect(plan('claude', 'y'.repeat(20_000), extra)?.carry).toBe('launch-file')
     expect(plan('aider', prompt, extra)?.carry).toBe('paste-after-ready')
+    // An AI button's paste is main's, which ran in WSL too.
+    const button = { ...extra, paste: 'once-agent-runs' as const }
+    expect(plan('gemini', 'y'.repeat(20_000), button)?.carry).toBe('paste-after-ready')
   })
 
   it('pastes on a paired host what its line cannot carry typed, even for Claude', () => {

src/shared/launch-prompt-carry.ts

@@ -69,6 +69,16 @@ export function launchPromptNeedsPasteRefusal(
         'paste the prompt once it opens.'
 }
 
+/**
+ * The paste a caller has for a prompt left until the agent is ready:
+ * - `never`: none, so the line carries the prompt, as main did;
+ * - `when-host-proves-agent`: #24257's guarded paste, refused where the host cannot prove the agent
+ *   is in front;
+ * - `once-agent-runs`: the desktop paste main uses for AI buttons and notes sends on every host,
+ *   written once the agent's process owns the terminal.
+ */
+export type LaunchPromptPaste = 'never' | 'when-host-proves-agent' | 'once-agent-runs'
+
 export type CarriedPlanArgs = {
   agent: TuiAgent
   prompt: string
@@ -78,9 +88,8 @@ export type CarriedPlanArgs = {
   launchFile?: LaunchFile
   /** The host the launch runs on (`describeLaunchHost`). */
   host: LaunchHost
-  /** Whether the caller pastes a prompt left for after the agent is ready. One that cannot still
-   *  starts the agent with the prompt on its line, as main did. */
-  canPasteAfterReady: boolean
+  /** The caller's paste for a prompt the line does not carry. */
+  paste: LaunchPromptPaste
 }
 
 export function agentReadsLaunchFile(agent: TuiAgent): boolean {
@@ -106,11 +115,11 @@ function windowsLineCarriesExactly(prompt: string, line: string, shell: AgentSta
 /**
  * The one carry rule. The prompt rides the agent's line: a host that stages (POSIX, SSH, WSL)
  * stages it when it is long or multi-line, and a Windows host types it when its shell carries the
- * text exactly. It rides a launch file when it is past the argv ceiling, when a Windows line would
- * damage it, or past a paired host's typed budget. A launch file goes only to an agent measured
- * reading one, on a host that writes it. Otherwise the prompt is pasted once the agent is ready,
- * unless the host cannot prove the agent is in front to paste into or the caller has no paste:
- * then the line carries it, as main typed it.
+ * text exactly. When the line cannot (past the argv ceiling, damaged by a Windows shell, past a
+ * paired host's typed budget), it rides a launch file, which goes only to an agent measured reading
+ * one, on a host that writes it; on Windows, a caller whose paste main used gets that paste first.
+ * Failing a file it is pasted once the agent is ready, unless the caller's paste cannot reach the
+ * agent on this host: then the line carries it, as main typed it.
  */
 export function carryLaunchPrompt<A extends CarriedPlanArgs, P extends { launchCommand: string }>(
   args: A,
@@ -135,12 +144,20 @@ export function carryLaunchPrompt<A extends CarriedPlanArgs, P extends { launchC
   if (mode === 'stdin-after-start') {
     return pasteAfterReady()
   }
+  const pasteReachesAgent =
+    args.paste === 'once-agent-runs' ||
+    (args.paste === 'when-host-proves-agent' && args.host.provesAgentInFront)
   const lineOrPaste = (): LaunchPromptPlan<P> | null => {
-    const pasteIsSafe = args.host.provesAgentInFront && args.canPasteAfterReady
-    const plan = pasteIsSafe ? null : buildLine(args)
+    const plan = pasteReachesAgent ? null : buildLine(args)
     return plan ? { carry: 'on-line', plan } : pasteAfterReady()
   }
   const viaLaunchFile = (): LaunchPromptPlan<P> | null => {
+    // Why paste first on Windows: main pastes this caller's prompts, so the agent gets the user's
+    // text; there a pointer would replace nearly every generated (multi-line) prompt. Temporary,
+    // until the agent's own argv carries multi-line text past cmd without a shim re-parsing it.
+    if (args.paste === 'once-agent-runs' && args.platform === 'win32') {
+      return pasteAfterReady()
+    }
     // Why: an agent not measured reading the file would stop on an approval or refuse the path.
     if (args.host.paired || !agentReadsLaunchFile(args.agent)) {
       return lineOrPaste()

src/shared/launch-prompt-plan.test-fixture.ts

@@ -18,8 +18,8 @@ export type PlannedLaunchForTest = AgentStartupPlan & {
 /** `planLaunchPrompt`, flattened; null where it answers null, or for an empty prompt unless
  *  `allowEmptyPromptLaunch`, as the builder did before the outcome was explicit. */
 export function planLaunchForTest(
-  args: Omit<AgentLaunchPromptArgs, 'host' | 'canPasteAfterReady'> &
-    Partial<Pick<AgentLaunchPromptArgs, 'host' | 'canPasteAfterReady'>> & {
+  args: Omit<AgentLaunchPromptArgs, 'host' | 'paste'> &
+    Partial<Pick<AgentLaunchPromptArgs, 'host' | 'paste'>> & {
       allowEmptyPromptLaunch?: boolean
     }
 ): PlannedLaunchForTest | null {
@@ -29,7 +29,7 @@ export function planLaunchForTest(
   }
   const planned = planLaunchPrompt({
     ...launchArgs,
-    // A local launch on the platform under test, by a caller that pastes, unless the test says.
+    // A local launch on the platform under test, with #24257's guarded paste, unless the test says.
     host:
       args.host ??
       describeLaunchHost({
@@ -38,7 +38,7 @@ export function planLaunchForTest(
         hostPlatform: args.platform,
         paired: false
       }),
-    canPasteAfterReady: args.canPasteAfterReady ?? true
+    paste: args.paste ?? 'when-host-proves-agent'
   })
   if (!planned) {
     return null

src/shared/tui-agent-startup.ts

@@ -15,6 +15,7 @@ import {
   carryLaunchPrompt,
   launchFileDirectoryGrant,
   windowsShellDamagesPrompt,
+  type LaunchPromptPaste,
   type LaunchPromptPlan
 } from './launch-prompt-carry'
 import { TUI_AGENT_CONFIG } from './tui-agent-config'
@@ -76,7 +77,7 @@ export type AgentLaunchPromptArgs = AgentStartupPlanInputs & {
   /** See `CarriedPlanArgs`. */
   host: LaunchHost
   /** See `CarriedPlanArgs`. */
-  canPasteAfterReady: boolean
+  paste: LaunchPromptPaste
 }
 
 /**