fix(mobile): send an AI button's saved agent arguments with its launch

The desktop's direct launches for "Fix checks", "Resolve conflicts" and commit
recovery pass the action's saved agent arguments to agent.launch; the phone
honoured the saved agent but dropped its arguments. It now sends them the same
way: absent when none are saved, so the host keeps the user's configured
defaults. A host that predates the field ignores it.

mobile/src/session/mobile-existing-agent-launch.ts

@@ -50,6 +50,7 @@ export async function launchAgentInExistingWorkspace(args: {
   hostCapabilities: readonly string[] | null | undefined
   worktreeId: string
   agent: TuiAgent
+  agentArgs?: string
   prompt?: AgentLaunchPrompt
   launchSource?: string
   // Injected in tests; each call is one new operation, so a later tap never replays this one.
@@ -62,6 +63,7 @@ export async function launchAgentInExistingWorkspace(args: {
     agent: args.agent,
     worktreeId: args.worktreeId,
     operationId: (args.mintOperationId ?? structuredSessionOperationId)(),
+    ...(args.agentArgs !== undefined ? { agentArgs: args.agentArgs } : {}),
     ...(args.prompt ? { prompt: args.prompt } : {}),
     ...(args.launchSource ? { launchSource: args.launchSource } : {})
   })

mobile/src/session/mobile-source-control-launch-agent.ts

@@ -5,7 +5,10 @@
 
 import type { GlobalSettings } from '../../../src/shared/global-settings-types'
 import type { Repo } from '../../../src/shared/repo-types'
-import type { SourceControlLaunchActionId } from '../../../src/shared/source-control-ai-actions'
+import type {
+  SourceControlActionRecipe,
+  SourceControlLaunchActionId
+} from '../../../src/shared/source-control-ai-actions'
 import { resolveSourceControlActionRecipe } from '../../../src/shared/source-control-ai'
 import {
   pickSourceControlLaunchAgent,
@@ -17,8 +20,8 @@ import { isMobileTuiAgent } from '../tasks/mobile-tui-agents'
 import type { MobileAgentLaunchContext } from './mobile-new-tab-agent-loader'
 
 export type MobileSourceControlLaunchAgent =
-  | { kind: 'agent'; agent: TuiAgent }
-  | { kind: 'unavailable'; message: string }
+  /** `agentArgs`: the recipe's saved launch arguments, sent as the desktop sends them. */
+  { kind: 'agent'; agent: TuiAgent; agentArgs?: string } | { kind: 'unavailable'; message: string }
 
 type LaunchAgentSettings = Pick<
   GlobalSettings,
@@ -32,7 +35,8 @@ export function resolveMobileSourceControlLaunchAgent(
 ): MobileSourceControlLaunchAgent {
   const settings = readLaunchAgentSettings(context.settings)
   const detectedAgents = context.detectedAgents.filter(isMobileTuiAgent)
-  const savedAgent = actionId ? readSavedAgent(settings, context.repo, actionId) : null
+  const recipe = actionId ? readSavedRecipe(settings, context.repo, actionId) : null
+  const savedAgent = readSourceControlLaunchRecipeAgentId(recipe)
   // Why: the phone has no pre-launch dialog showing the pick, so a saved agent that can't run here
   // is an error, as on the desktop's direct launch, rather than a silent swap to another agent.
   if (
@@ -51,7 +55,11 @@ export function resolveMobileSourceControlLaunchAgent(
     disabledAgents: settings?.disabledTuiAgents
   })
   return agent
-    ? { kind: 'agent', agent }
+    ? {
+        kind: 'agent',
+        agent,
+        ...(recipe?.agentArgs !== undefined ? { agentArgs: recipe.agentArgs } : {})
+      }
     : { kind: 'unavailable', message: 'No enabled AI agent was detected on this workspace host.' }
 }
 
@@ -63,15 +71,13 @@ function readLaunchAgentSettings(settings: unknown): LaunchAgentSettings | null
   return settings as LaunchAgentSettings
 }
 
-function readSavedAgent(
+function readSavedRecipe(
   settings: LaunchAgentSettings | null,
   repo: unknown,
   actionId: SourceControlLaunchActionId
-): TuiAgent | null {
+): SourceControlActionRecipe | null {
   try {
-    return readSourceControlLaunchRecipeAgentId(
-      resolveSourceControlActionRecipe({ settings, repo: readRepoOverrides(repo), actionId })
-    )
+    return resolveSourceControlActionRecipe({ settings, repo: readRepoOverrides(repo), actionId })
   } catch {
     // A recipe the phone cannot read must not block the button; the default agent still applies.
     return null

mobile/src/session/pr-ai-triage-launch.test.ts

@@ -106,6 +106,8 @@ describe('launchAgentWithPrompt', () => {
       prompt: { text: 'Fix the failing checks', delivery: 'submit' },
       launchSource: 'task_page'
     })
+    // No saved arguments: the host applies the user's configured defaults.
+    expect(launchParams(sendRequest)).not.toHaveProperty('agentArgs')
     expect(sendRequest.mock.calls.some(([method]) => method === 'terminal.send')).toBe(false)
     expect(
       sendRequest.mock.calls.some(([method]) => method === 'session.tabs.createTerminal')
@@ -124,6 +126,18 @@ describe('launchAgentWithPrompt', () => {
     expect(launchParams(sendRequest)).toMatchObject({ agent: 'claude' })
   })
 
+  it("sends the action's saved agent arguments, as the desktop does", async () => {
+    const { client, sendRequest } = hostClient({
+      settings: {
+        defaultTuiAgent: 'claude',
+        sourceControlAi: { actions: { fixChecks: { agentArgs: '--model opus' } } }
+      },
+      launch: launchedWith({ delivery: 'submit', outcome: 'handed-to-terminal' })
+    })
+    await run(client)
+    expect(launchParams(sendRequest)).toMatchObject({ agent: 'claude', agentArgs: '--model opus' })
+  })
+
   it('refuses rather than swaps when the saved agent is not on this host', async () => {
     const { client, sendRequest } = hostClient({
       settings: { sourceControlAi: { actions: { fixChecks: { agentId: 'gemini' } } } },

mobile/src/session/pr-ai-triage-launch.ts

@@ -52,6 +52,7 @@ export async function launchAgentWithPrompt(args: {
     hostCapabilities: args.hostCapabilities,
     worktreeId: args.worktreeId,
     agent: resolved.agent,
+    ...(resolved.agentArgs !== undefined ? { agentArgs: resolved.agentArgs } : {}),
     prompt: { text: args.prompt, delivery: 'submit' },
     launchSource: args.launchSource
   })

mobile/src/tasks/agent-launch-request.ts

@@ -80,6 +80,7 @@ export function agentLaunchExistingParams(args: {
   agent: TuiAgent
   worktreeId: string
   operationId: string
+  agentArgs?: string
   prompt?: AgentLaunchPrompt
   launchSource?: string
 }): RpcSendParams<'agent.launchReplay'> {
@@ -87,6 +88,7 @@ export function agentLaunchExistingParams(args: {
     agent: args.agent,
     operationId: args.operationId,
     target: { kind: 'existing', worktree: `id:${args.worktreeId}` },
+    ...(args.agentArgs !== undefined ? { agentArgs: args.agentArgs } : {}),
     ...(args.prompt ? { prompt: args.prompt } : {}),
     ...(args.launchSource ? { launchSource: args.launchSource } : {})
   }