refactor(mobile): export the New Workspace SSH target key

Names an SSH target by its holding host and id, so other server-aware screens can key their SSH
state the same way.

Claude-Session: https://claude.ai/code/session_01JNnE9qzUZMMnqpZWCqM3nb

mobile/src/components/use-new-workspace-execution-target.ts

@@ -9,6 +9,7 @@ import {
 } from '../tasks/mobile-workspace-source-operations'
 import {
   deriveWorkspaceSshGate,
+  workspaceSshTargetKey,
   type WorkspaceSshGate,
   type WorkspaceSshRecord
 } from '../tasks/workspace-ssh-gate'
@@ -43,8 +44,7 @@ export function useNewWorkspaceExecutionTarget(args: {
   connect: () => Promise<void>
 } {
   const { client, connectionId, server, visible } = args
-  // Why the host too: the desktop and a server can each hold a target with the same id.
-  const target = JSON.stringify([server ?? null, connectionId])
+  const target = workspaceSshTargetKey(server, connectionId)
   const [sshState, setSshEntry] = useState<SshStateEntry | null>(null)
   const setSshState = (record: WorkspaceSshRecord) => setSshEntry({ target, record })
   // A connect reply lands only while its target is still the one shown, so it never overwrites another's.

mobile/src/tasks/workspace-ssh-gate.test.ts

@@ -1,7 +1,23 @@
 import { describe, expect, it } from 'vitest'
-import { deriveWorkspaceSshGate, workspaceSshStatusLabel } from './workspace-ssh-gate'
+import {
+  deriveWorkspaceSshGate,
+  workspaceSshStatusLabel,
+  workspaceSshTargetKey
+} from './workspace-ssh-gate'
 
 describe('workspace SSH gate', () => {
+  it('keys a target by the host holding it, so same-named targets on two hosts differ', () => {
+    expect(workspaceSshTargetKey(undefined, 'devbox')).not.toBe(
+      workspaceSshTargetKey('runtime:env-1', 'devbox')
+    )
+    expect(workspaceSshTargetKey('runtime:env-1', 'devbox')).not.toBe(
+      workspaceSshTargetKey('runtime:env-2', 'devbox')
+    )
+    expect(workspaceSshTargetKey('runtime:env-1', 'devbox')).toBe(
+      workspaceSshTargetKey('runtime:env-1', 'devbox')
+    )
+  })
+
   it('does not gate local repositories', () => {
     expect(
       deriveWorkspaceSshGate({

mobile/src/tasks/workspace-ssh-gate.ts

@@ -1,3 +1,4 @@
+import type { ExecutionHostId } from '../../../src/shared/execution-host'
 import type { SshConnectionState, SshConnectionStatus } from '../../../src/shared/ssh-types'
 
 /**
@@ -14,6 +15,17 @@ export type WorkspaceSshRecord = Omit<SshConnectionState, 'error' | 'reconnectAt
   reconnectAttempt?: number
 }
 
+/**
+ * Names an SSH target by the host holding it as well as its id: the desktop and a server can each
+ * hold a target with the same id. `server` is undefined for the desktop's own targets.
+ */
+export function workspaceSshTargetKey(
+  server: ExecutionHostId | undefined,
+  connectionId: string | null
+): string {
+  return JSON.stringify([server ?? null, connectionId])
+}
+
 export type WorkspaceSshGate = {
   status: SshConnectionStatus | null
   requiresConnection: boolean