diff --git a/src/main/runtime/rpc/methods/client-ui.test.ts b/src/main/runtime/rpc/methods/client-ui.test.ts
index 3a26b1c615d..683d9762fc7 100644
--- a/src/main/runtime/rpc/methods/client-ui.test.ts
+++ b/src/main/runtime/rpc/methods/client-ui.test.ts
@@ -62,7 +62,7 @@ describe('client UI RPC methods', () => {
     expect(response).toMatchObject({ ok: true, result: { settings } })
   })
 
-  it('rejects paired attempts to mutate the host-owned structured chat setting', async () => {
+  it('rejects mobile attempts to mutate the host-owned structured chat setting', async () => {
     const runtime = {
       getRuntimeId: () => 'test-runtime',
       updateClientSettings: vi.fn()
@@ -70,7 +70,8 @@ describe('client UI RPC methods', () => {
     const dispatcher = new RpcDispatcher({ runtime, methods: CLIENT_UI_METHODS })
 
     const response = await dispatcher.dispatch(
-      makeRequest('settings.update', { experimentalStructuredNativeChat: true })
+      makeRequest('settings.update', { experimentalStructuredNativeChat: true }),
+      { clientKind: 'mobile' }
     )
 
     expect(response).toMatchObject({
@@ -80,6 +81,27 @@ describe('client UI RPC methods', () => {
     expect(runtime.updateClientSettings).not.toHaveBeenCalled()
   })
 
+  it('lets a paired desktop peer enable structured chat on a headless host', async () => {
+    const runtime = {
+      getRuntimeId: () => 'test-runtime',
+      updateClientSettings: vi.fn(async () => ({ experimentalStructuredNativeChat: true }))
+    } as unknown as OrcaRuntimeService
+    const dispatcher = new RpcDispatcher({ runtime, methods: CLIENT_UI_METHODS })
+
+    const response = await dispatcher.dispatch(
+      makeRequest('settings.update', { experimentalStructuredNativeChat: true }),
+      { clientKind: 'runtime' }
+    )
+
+    expect(response).toMatchObject({
+      ok: true,
+      result: { settings: { experimentalStructuredNativeChat: true } }
+    })
+    expect(runtime.updateClientSettings).toHaveBeenCalledWith({
+      experimentalStructuredNativeChat: true
+    })
+  })
+
   it('persists the runtime host task source settings for mobile Tasks', async () => {
     const settings = {
       defaultTuiAgent: null,
diff --git a/src/main/runtime/rpc/methods/client-ui.ts b/src/main/runtime/rpc/methods/client-ui.ts
index 6ed36a6fe83..5a21b222732 100644
--- a/src/main/runtime/rpc/methods/client-ui.ts
+++ b/src/main/runtime/rpc/methods/client-ui.ts
@@ -1,6 +1,6 @@
 import { omitPairingLocalUiFields } from '../../../../shared/pairing-local-ui-fields'
 import type { PersistedUIState } from '../../../../shared/persisted-ui-state-types'
-import { defineMethod } from '../core'
+import { InvalidArgumentError, defineMethod } from '../core'
 import {
   NativeChatSessionOptionsMutation,
   PRBotAuthorOverrideUpdate,
@@ -21,9 +21,16 @@ export const CLIENT_UI_METHODS = [
   defineMethod({
     name: 'settings.update',
     params: SettingsUpdate,
-    handler: async (params, { runtime }) => ({
-      settings: await runtime.updateClientSettings(params)
-    })
+    handler: async (params, { runtime, clientKind }) => {
+      // A headless host ships no settings UI, so this RPC is its only admission lever -- but
+      // the phone has no surface for host policy, so it stays refused there as before.
+      if (clientKind === 'mobile' && params.experimentalStructuredNativeChat !== undefined) {
+        throw new InvalidArgumentError(
+          'Structured chat admission is host policy and cannot be set from mobile.'
+        )
+      }
+      return { settings: await runtime.updateClientSettings(params) }
+    }
   }),
   defineMethod({
     name: 'settings.getTerminalQuickCommands',
diff --git a/src/main/runtime/runtime-client-settings-structured-admission.test.ts b/src/main/runtime/runtime-client-settings-structured-admission.test.ts
new file mode 100644
index 00000000000..c69ec2aaf42
--- /dev/null
+++ b/src/main/runtime/runtime-client-settings-structured-admission.test.ts
@@ -0,0 +1,85 @@
+import { describe, expect, it, vi } from 'vitest'
+import { OrcaRuntimeService } from './orca-runtime'
+import { supportsStructuredAgentSessions } from './rpc/methods/structured-agent-session-policy'
+import { SettingsUpdate } from '../../shared/rpc-contract/client-settings-params'
+import { STRUCTURED_AGENT_SESSION_RUNTIME_CAPABILITY } from '../../shared/protocol-version'
+import type { GlobalSettings } from '../../shared/global-settings-types'
+
+vi.mock('electron', () => ({
+  BrowserWindow: { fromId: vi.fn(() => null) },
+  webContents: { fromId: vi.fn(() => null) },
+  ipcMain: { on: vi.fn(), removeListener: vi.fn() },
+  app: { getPath: vi.fn(() => '/tmp') }
+}))
+
+function createHeadlessHost(structuredNativeChatEnabled: boolean): OrcaRuntimeService {
+  let settings: Partial<GlobalSettings> = {
+    workspaceDir: '/tmp/orca-remote-admission-update',
+    nestWorkspaces: false,
+    refreshLocalBaseRefOnWorktreeCreate: false,
+    compactWorktreeCards: false,
+    experimentalStructuredNativeChat: structuredNativeChatEnabled
+  }
+  const store = {
+    getSettings: () => settings,
+    updateSettings: (updates: Partial<GlobalSettings>) => {
+      settings = { ...settings, ...updates }
+      return settings
+    }
+  }
+  return new OrcaRuntimeService(store as never)
+}
+
+/** Goes through the real RPC decoder, which is strict: an unmodelled key is rejected outright. */
+async function applyPairedSettingsUpdate(
+  runtime: OrcaRuntimeService,
+  payload: Record<string, unknown>
+): Promise<void> {
+  await runtime.updateClientSettings(SettingsUpdate.parse(payload))
+}
+
+function admitsCapableRemoteCaller(runtime: OrcaRuntimeService): boolean {
+  return supportsStructuredAgentSessions({
+    runtime,
+    clientKind: 'runtime',
+    clientCapabilities: [STRUCTURED_AGENT_SESSION_RUNTIME_CAPABILITY]
+  })
+}
+
+describe('structured-chat admission over the paired settings update', () => {
+  it('lets a paired client flip a headless host from refusing to admitting', async () => {
+    const runtime = createHeadlessHost(false)
+    expect(admitsCapableRemoteCaller(runtime)).toBe(false)
+
+    await applyPairedSettingsUpdate(runtime, { experimentalStructuredNativeChat: true })
+
+    expect(admitsCapableRemoteCaller(runtime)).toBe(true)
+  })
+
+  it('publishes the flipped admission on the next status read', async () => {
+    const runtime = createHeadlessHost(false)
+    expect(runtime.getStatus().structuredSessionAdmission).toEqual({ enabled: false })
+
+    await applyPairedSettingsUpdate(runtime, { experimentalStructuredNativeChat: true })
+
+    expect(runtime.getStatus().structuredSessionAdmission).toEqual({ enabled: true })
+  })
+
+  it('turns admission back off when the client sends false', async () => {
+    const runtime = createHeadlessHost(true)
+
+    await applyPairedSettingsUpdate(runtime, { experimentalStructuredNativeChat: false })
+
+    expect(admitsCapableRemoteCaller(runtime)).toBe(false)
+    expect(runtime.getStatus().structuredSessionAdmission).toEqual({ enabled: false })
+  })
+
+  it('leaves the setting untouched when an update omits the key', async () => {
+    const runtime = createHeadlessHost(true)
+
+    await applyPairedSettingsUpdate(runtime, { compactWorktreeCards: true })
+
+    expect(runtime.getClientSettings().experimentalStructuredNativeChat).toBe(true)
+    expect(runtime.getClientSettings().compactWorktreeCards).toBe(true)
+  })
+})
diff --git a/src/main/runtime/runtime-client-settings.ts b/src/main/runtime/runtime-client-settings.ts
index 900900700f3..a8536c9c4df 100644
--- a/src/main/runtime/runtime-client-settings.ts
+++ b/src/main/runtime/runtime-client-settings.ts
@@ -68,6 +68,7 @@ export type RuntimeClientSettingsUpdate = Pick<
   | 'defaultLinearTeamSelection'
   | 'githubProjects'
   | 'experimentalNewWorktreeCardStyle'
+  | 'experimentalStructuredNativeChat'
   | 'compactWorktreeCards'
   | 'minimaxGroupId'
   | 'minimaxUsageModels'
diff --git a/src/shared/rpc-contract/client-settings-params.ts b/src/shared/rpc-contract/client-settings-params.ts
index def24ddc703..3dad005db68 100644
--- a/src/shared/rpc-contract/client-settings-params.ts
+++ b/src/shared/rpc-contract/client-settings-params.ts
@@ -106,6 +106,9 @@ export const SettingsUpdate = z
       .enum(['issues', 'my-issues', 'prs', 'my-prs', 'review', 'all'])
       .optional(),
     experimentalNewWorktreeCardStyle: z.boolean().optional(),
+    // The only lever a headless host has for structured-chat admission: it ships no settings UI,
+    // so without this key a fresh `orca serve` or peer host refuses the surface forever.
+    experimentalStructuredNativeChat: z.boolean().optional(),
     agentStatusHooksEnabled: z.boolean().optional(),
     defaultRepoSelection: z.array(z.string()).nullable().optional(),
     defaultLinearTeamSelection: z.array(z.string()).nullable().optional(),