refactor(mobile): list server rows through one desktop fetch, with no side effect on listing

The phone now always lists a server's rows through mobileRelay.hosts.worktrees, so the
desktop's own fetch is both the live source and the cache, and stamping stays in main.

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

src/main/runtime/mobile-desktop-relay/mobile-relay-host-catalog.integration.test.ts

@@ -148,7 +148,7 @@ describe('mobile relay hosts: phone -> desktop lists the servers it shows', () =
     return { box, contact, phoneCall }
   }
 
-  it('lists cached rows for an unreachable server and live rows for an update-needed one', async () => {
+  it('lists rows live through the desktop, then its last rows as stale once a server is unreachable', async () => {
     const { box, contact, phoneCall } = await startTopology()
 
     await expect(phoneCall('mobileRelay.hosts.list')).resolves.toEqual({

src/main/runtime/mobile-desktop-relay/mobile-relay-host-catalog.test.ts

@@ -89,7 +89,7 @@ function catalog(hosts: MobileDesktopRelayHosts, labels = new Map()) {
 }
 
 describe('mobile relay host catalog', () => {
-  it("lists every configured server with the desktop's health and whether it can relay", () => {
+  it("lists every configured server with the desktop's health and whether it can relay", async () => {
     const { hosts, call } = fakeHosts([
       { id: 'ready', name: 'Box', snapshot: snapshot('ready', 'live') },
       { id: 'old', name: 'ThinkPad', snapshot: snapshot('old', 'live', false) },
@@ -108,6 +108,9 @@ describe('mobile relay host catalog', () => {
       { hostId: 'runtime:old-down', label: 'Pi', health: 'connecting', relay: 'update-needed' },
       { hostId: 'runtime:new', label: 'Fresh', health: 'connecting', relay: 'unavailable' }
     ])
+    // Listing reads what the desktop already knows; it never contacts a server.
+    await new Promise((resolve) => setTimeout(resolve, 0))
+    expect(call).not.toHaveBeenCalled()
   })
 
   it('encodes an environment id into the host id the desktop uses', () => {
@@ -156,8 +159,7 @@ describe('mobile relay host catalog', () => {
     ])
     call.mockResolvedValue(psReply([{ worktreeId: 'w', hostId: 'local', status: 'working' }]))
     const { catalog: hostCatalog, advance } = catalog(hosts)
-    hostCatalog.list()
-    await vi.waitFor(() => expect(call).toHaveBeenCalledTimes(1))
+    await hostCatalog.worktrees('runtime:env')
     advance(5_000)
 
     state.environments = [{ id: 'env', name: 'Box', snapshot: snapshot('env', 'unreachable') }]
@@ -209,19 +211,21 @@ describe('mobile relay host catalog', () => {
     await expect(hostCatalog.worktrees('runtime:env')).resolves.toEqual({ worktrees: null })
   })
 
-  it('shares one in-flight fetch per server between listing and a rows request', async () => {
+  it('shares one in-flight fetch per server between concurrent rows requests', async () => {
     const { hosts, call } = fakeHosts([
       { id: 'env', name: 'Box', snapshot: snapshot('env', 'live') }
     ])
     let answerFetch: (response: RuntimeRpcResponse<unknown>) => void = () => {}
     call.mockReturnValue(new Promise((resolve) => (answerFetch = resolve)))
     const { catalog: hostCatalog } = catalog(hosts)
-    hostCatalog.list()
-    hostCatalog.list()
-    const rows = hostCatalog.worktrees('runtime:env')
+    const first = hostCatalog.worktrees('runtime:env')
+    const second = hostCatalog.worktrees('runtime:env')
     await vi.waitFor(() => expect(call).toHaveBeenCalledTimes(1))
     answerFetch(psReply([{ worktreeId: 'w', hostId: 'local' }]))
-    await expect(rows).resolves.toMatchObject({ stale: false })
+    await expect(Promise.all([first, second])).resolves.toMatchObject([
+      { stale: false },
+      { stale: false }
+    ])
     expect(call).toHaveBeenCalledTimes(1)
   })
 })

src/main/runtime/mobile-desktop-relay/mobile-relay-host-catalog.ts

@@ -1,14 +1,17 @@
 import { z } from 'zod'
 import { DELEGATED_MOBILE_DEVICES_RUNTIME_CAPABILITY } from '../../../shared/delegated-mobile-device-contract'
-import { parseExecutionHostId, type ExecutionHostId } from '../../../shared/execution-host'
-import { buildExecutionHostRegistry } from '../../../shared/execution-host-registry'
 import {
-  stampServerWorktreeRows,
-  type MobileRelayHost,
-  type MobileRelayHostRelay,
-  type MobileRelayHostsListResult,
-  type MobileRelayHostWorktreesResult,
-  type MobileRelayServerWorktreeRow
+  parseExecutionHostId,
+  toRuntimeExecutionHostId,
+  type ExecutionHostId
+} from '../../../shared/execution-host'
+import { buildExecutionHostRegistry } from '../../../shared/execution-host-registry'
+import type {
+  MobileRelayHost,
+  MobileRelayHostRelay,
+  MobileRelayHostsListResult,
+  MobileRelayHostWorktreesResult,
+  MobileRelayServerWorktreeRow
 } from '../../../shared/mobile-relay-hosts-contract'
 import { lastVerifiedRuntimeStatus } from '../../../shared/runtime-host-status'
 import type { RuntimeStatus } from '../../../shared/runtime-types'
@@ -49,15 +52,13 @@ export class MobileRelayHostCatalog {
   ) {}
 
   list(): MobileRelayHostsListResult {
-    const hosts = this.describe()
-    for (const host of hosts) {
-      // Why: keeps the last list warm while the server answers, for when it stops answering.
-      if (host.health === 'available') {
-        void this.refresh(host)
-      }
-    }
     return {
-      hosts: hosts.map(({ hostId, label, health, relay }) => ({ hostId, label, health, relay }))
+      hosts: this.describe().map(({ hostId, label, health, relay }) => ({
+        hostId,
+        label,
+        health,
+        relay
+      }))
     }
   }
 
@@ -164,3 +165,15 @@ function relayVerdict(
   }
   return health === 'available' ? 'ready' : 'unavailable'
 }
+
+/**
+ * A server's rows name hosts relative to that server (`local`, its own `ssh:` targets). Like the
+ * desktop sidebar, the phone shows every one of them under the server, so all become its host id.
+ */
+function stampServerWorktreeRows<Row extends { hostId?: string }>(
+  environmentId: string,
+  rows: readonly Row[]
+): (Row & { hostId: `runtime:${string}` })[] {
+  const hostId = toRuntimeExecutionHostId(environmentId)
+  return rows.map((row) => ({ ...row, hostId }))
+}

src/shared/mobile-relay-hosts-contract.ts

@@ -1,5 +1,4 @@
 import { z } from 'zod'
-import { toRuntimeExecutionHostId } from './execution-host'
 import type { ExecutionHostHealth } from './execution-host-health'
 
 // Why: both are answered by the paired desktop itself; the phone lists servers the desktop shows.
@@ -38,15 +37,3 @@ export type MobileRelayHostWorktreesResult =
       stale: boolean
     }
   | { worktrees: null }
-
-/**
- * A server's rows name hosts relative to that server (`local`, its own `ssh:` targets). Like the
- * desktop sidebar, the phone shows every one of them under the server, so all become its host id.
- */
-export function stampServerWorktreeRows<Row extends { hostId?: string }>(
-  environmentId: string,
-  rows: readonly Row[]
-): (Row & { hostId: `runtime:${string}` })[] {
-  const hostId = toRuntimeExecutionHostId(environmentId)
-  return rows.map((row) => ({ ...row, hostId }))
-}