diff --git a/src/main/runtime/orca-runtime-mobile-markdown-tab-routes.test.ts b/src/main/runtime/orca-runtime-mobile-markdown-tab-routes.test.ts
index bc17398e0c9..c2df94fb9d7 100644
--- a/src/main/runtime/orca-runtime-mobile-markdown-tab-routes.test.ts
+++ b/src/main/runtime/orca-runtime-mobile-markdown-tab-routes.test.ts
@@ -29,7 +29,7 @@ vi.mock('./files/chat-scratch-file-root', async (importOriginal) => ({
 
 const { OrcaRuntimeService } = await import('./orca-runtime-test-mocks.spec')
 await import('./orca-runtime-test-lifecycle.spec')
-const { TEST_WORKTREE_ID, makeRuntimeStoreWithWorkspaceSession } =
+const { TEST_REPO_ID, TEST_WORKTREE_ID, makeRuntimeStoreWithWorkspaceSession, store } =
   await import('./orca-runtime-test-fixtures.spec')
 
 type Runtime = InstanceType<typeof OrcaRuntimeService>
@@ -454,7 +454,7 @@ describe("a phone's Markdown tab with a desktop window attached", () => {
   ): RuntimeMobileSessionMarkdownTab {
     return {
       type: 'markdown',
-      id: 'tab-readme',
+      id: readme,
       title: 'README.md',
       filePath: readme,
       relativePath: 'README.md',
@@ -470,12 +470,52 @@ describe("a phone's Markdown tab with a desktop window attached", () => {
     }
   }
 
+  /** As the window saves it: each open editor also holds its unified tab (id = path) and group. */
+  function withSavedEditorTabs(session: WorkspaceSessionState): WorkspaceSessionState {
+    const files = session.openFilesByWorktree?.[TEST_WORKTREE_ID] ?? []
+    const tabs = files.map((file, sortOrder) => ({
+      id: file.filePath,
+      entityId: file.filePath,
+      groupId: 'group-1',
+      worktreeId: TEST_WORKTREE_ID,
+      contentType: 'editor' as const,
+      label: file.relativePath,
+      customLabel: null,
+      color: null,
+      sortOrder,
+      createdAt: 1
+    }))
+    return {
+      ...session,
+      unifiedTabs: { [TEST_WORKTREE_ID]: tabs },
+      tabGroups: {
+        [TEST_WORKTREE_ID]: [
+          {
+            id: 'group-1',
+            worktreeId: TEST_WORKTREE_ID,
+            activeTabId: tabs[0]?.id ?? null,
+            tabOrder: tabs.map((tab) => tab.id)
+          }
+        ]
+      },
+      activeGroupIdByWorktree: { [TEST_WORKTREE_ID]: 'group-1' }
+    }
+  }
+
+  // Why the host ids: like the real Store, the fixture lists its partitions, which main's layout reads.
   function runtimeWithWindowTabs(
     tabs: RuntimeMobileSessionMarkdownTab[],
-    session = sessionWithReadme()
+    session = sessionWithReadme(),
+    ownerHostId: 'local' | 'ssh:ssh-1' = 'local'
   ): Runtime {
-    const harness = makeRuntimeStoreWithWorkspaceSession(session)
-    const runtime = new OrcaRuntimeService(harness.runtimeStore)
+    const harness = makeRuntimeStoreWithWorkspaceSession(withSavedEditorTabs(session), ownerHostId)
+    const repo = { ...store.getRepos()[0]!, executionHostId: ownerHostId }
+    const runtime = new OrcaRuntimeService({
+      ...harness.runtimeStore,
+      getRepos: () => [repo],
+      getRepo: (id: string) => (id === TEST_REPO_ID ? repo : undefined),
+      getWorkspaceSessionHostIds: () => [ownerHostId]
+    })
     runtime.attachWindow(1)
     runtime.syncWindowGraph(1, {
       tabs: [],
@@ -499,9 +539,9 @@ describe("a phone's Markdown tab with a desktop window attached", () => {
     const runtime = runtimeWithWindowTabs([windowTab({ isDirty: true })])
 
     await expect(
-      runtime.readMobileMarkdownTab(`id:${TEST_WORKTREE_ID}`, 'tab-readme')
+      runtime.readMobileMarkdownTab(`id:${TEST_WORKTREE_ID}`, readme)
     ).resolves.toMatchObject({
-      tabId: 'tab-readme',
+      tabId: readme,
       content: '# Notes\n',
       isDirty: true,
       source: 'file',
@@ -561,9 +601,11 @@ describe("a phone's Markdown tab with a desktop window attached", () => {
 
   it('reads an untitled tab read-only and never saves it', async () => {
     const runtime = runtimeWithWindowTabs([windowTab({ isUntitled: true, isDirty: true })])
+    // The phone lists the workspace before it reads a tab.
+    await runtime.listMobileSessionTabs(`id:${TEST_WORKTREE_ID}`)
 
     await expect(
-      runtime.readMobileMarkdownTab(`id:${TEST_WORKTREE_ID}`, 'tab-readme')
+      runtime.readMobileMarkdownTab(`id:${TEST_WORKTREE_ID}`, readme)
     ).resolves.toMatchObject({
       content: '# Notes\n',
       isDirty: true,
@@ -573,7 +615,7 @@ describe("a phone's Markdown tab with a desktop window attached", () => {
     await expect(
       runtime.saveMobileMarkdownTab(
         `id:${TEST_WORKTREE_ID}`,
-        'tab-readme',
+        readme,
         hashMarkdownContent('# Notes\n'),
         '# Phone\n'
       )
@@ -611,6 +653,25 @@ describe("a phone's Markdown tab with a desktop window attached", () => {
     ).rejects.toThrow('unsupported_untitled')
     expect(existsSync(untitled)).toBe(false)
   })
+  it('keeps an SSH-hosted untitled tab read-only, refusing the save before reaching the host', async () => {
+    const runtime = runtimeWithWindowTabs(
+      [windowTab({ isUntitled: true, isDirty: true })],
+      sessionWithReadme(),
+      'ssh:ssh-1'
+    )
+
+    const listed = await runtime.listMobileSessionTabs(`id:${TEST_WORKTREE_ID}`)
+    expect(listed.tabs.find((tab) => tab.id === readme)).toMatchObject({ isUntitled: true })
+    await expect(
+      runtime.saveMobileMarkdownTab(
+        `id:${TEST_WORKTREE_ID}`,
+        readme,
+        hashMarkdownContent('# Notes\n'),
+        '# Phone\n'
+      )
+    ).rejects.toThrow('unsupported_untitled')
+    expect(await readFile(readme, 'utf8')).toBe('# Notes\n')
+  })
 })
 
 describe("a phone's Markdown tab with no window, on a desktop's untitled document", () => {
diff --git a/src/main/runtime/session-tabs/main-session-tab-rows.test.ts b/src/main/runtime/session-tabs/main-session-tab-rows.test.ts
index 2625f7d9899..9a2e2ac35aa 100644
--- a/src/main/runtime/session-tabs/main-session-tab-rows.test.ts
+++ b/src/main/runtime/session-tabs/main-session-tab-rows.test.ts
@@ -302,8 +302,8 @@ describe('session.tabs rows from main (layout-owner build)', () => {
     expect(merged).toMatchObject({ activeGroupId: 'g2', activeTabId: 'b1' })
   })
 
-  it("takes a markdown edit view's dirty state from the window", () => {
-    const markdown = (isDirty: boolean) => ({
+  it("takes a markdown edit view's dirty state and untitled flag from the window", () => {
+    const markdown = (isDirty: boolean, isUntitled?: true) => ({
       type: 'markdown' as const,
       id: 'm1',
       title: 'README.md',
@@ -316,14 +316,16 @@ describe('session.tabs rows from main (layout-owner build)', () => {
       sourceRelativePath: 'README.md',
       documentVersion: 'file:/wt/README.md',
       isDirty,
-      isActive: false
+      isActive: false,
+      ...(isUntitled ? { isUntitled } : {})
     })
     const merged = withMainSessionTabRows(
-      windowSnapshot([markdown(true)], ['m1'], 'm1'),
+      windowSnapshot([markdown(true, true)], ['m1'], 'm1'),
       mainProjection([markdown(false)], ['m1'], 'm1'),
       NONE_EXITED
     )
 
-    expect(merged.tabs[0]).toMatchObject({ id: 'm1', isDirty: true })
+    // Why: the saved session never records untitled, and the phone keeps such a tab read-only.
+    expect(merged.tabs[0]).toMatchObject({ id: 'm1', isDirty: true, isUntitled: true })
   })
 })
diff --git a/src/main/runtime/session-tabs/main-session-tab-rows.ts b/src/main/runtime/session-tabs/main-session-tab-rows.ts
index 6957346686e..4f146f0eabe 100644
--- a/src/main/runtime/session-tabs/main-session-tab-rows.ts
+++ b/src/main/runtime/session-tabs/main-session-tab-rows.ts
@@ -2,7 +2,8 @@
 // layout (projectSessionTabs). The window's live publication supplies what the user sees: selection,
 // the focused pane, dirty state and live terminal titles (main's copy of the view lags a debounced
 // save), the rows main's layout does not list yet, and the facts only the window has (terminal
-// theme, agent status, launch drafts, a markdown view's mode, file id and draft version).
+// theme, agent status, launch drafts, a markdown view's mode, file id, draft version and untitled
+// flag).
 
 import type { RuntimeMobileSessionSnapshotTab } from '../../../shared/runtime-mobile-session-tab-contracts'
 import { orderIdOf, placeInMainGroups, withStrayIn } from './main-session-tab-group-placement'
@@ -91,7 +92,9 @@ function withWindowFacts(row: Row, windowRow: Row | undefined, rules: MergeRules
       isDirty: windowRow.isDirty,
       mode: windowRow.mode,
       sourceFileId: windowRow.sourceFileId,
-      documentVersion: windowRow.documentVersion
+      documentVersion: windowRow.documentVersion,
+      // The saved session never records untitled; a phone save must not make its file.
+      ...(windowRow.isUntitled ? { isUntitled: true as const } : {})
     }
   }
   if (row.type === 'file' && windowRow?.type === 'file') {