diff --git a/src/main/runtime/orca-runtime.test.ts b/src/main/runtime/orca-runtime.test.ts
index ec4d930ad793..4c56a99ea4ae 100644
--- a/src/main/runtime/orca-runtime.test.ts
+++ b/src/main/runtime/orca-runtime.test.ts
@@ -31367,6 +31367,88 @@ describe('OrcaRuntimeService', () => {
     expect(getSession().terminalLayoutsByTabId['host-tab']).toBeUndefined()
   })
 
+  it('closes headless terminal parents whose persisted record is missing instead of resurrecting them', async () => {
+    const layout = makeHeadlessTerminalLayout({
+      [HEADLESS_LEAF_ID]: 'pty-a',
+      [HEADLESS_SECOND_LEAF_ID]: 'pty-b'
+    })
+    const { runtimeStore, getSession, setSession } = makeRuntimeStoreWithWorkspaceSession(
+      makeWorkspaceSessionWithHeadlessTerminal({
+        tabsByWorktree: {
+          [TEST_WORKTREE_ID]: [
+            {
+              id: 'host-tab',
+              ptyId: 'pty-a',
+              worktreeId: TEST_WORKTREE_ID,
+              title: 'Persisted Terminal',
+              customTitle: null,
+              color: null,
+              sortOrder: 0,
+              createdAt: 1
+            }
+          ]
+        },
+        terminalLayoutsByTabId: { 'host-tab': layout }
+      })
+    )
+    const kill = vi.fn(() => true)
+    const runtime = new OrcaRuntimeService(runtimeStore as never)
+    runtime.setPtyController({
+      write: () => true,
+      kill,
+      getForegroundProcess: async () => null,
+      listProcesses: async () => []
+    })
+    runtime.syncWindowGraph(1, {
+      tabs: [
+        {
+          tabId: 'host-tab',
+          worktreeId: TEST_WORKTREE_ID,
+          title: 'Persisted Terminal',
+          activeLeafId: HEADLESS_LEAF_ID,
+          layout: null
+        }
+      ],
+      leaves: [
+        {
+          tabId: 'host-tab',
+          worktreeId: TEST_WORKTREE_ID,
+          leafId: HEADLESS_LEAF_ID,
+          paneRuntimeId: 1,
+          ptyId: 'pty-a',
+          paneTitle: 'A'
+        },
+        {
+          tabId: 'host-tab',
+          worktreeId: TEST_WORKTREE_ID,
+          leafId: HEADLESS_SECOND_LEAF_ID,
+          paneRuntimeId: 2,
+          ptyId: 'pty-b',
+          paneTitle: 'B'
+        }
+      ]
+    })
+
+    // Why: warm the live snapshot, then drop the persisted row out-of-band to
+    // reproduce the persisted/live-state drift (#10747, #12920) — a
+    // never-persisted background tab or a close that de-persisted then failed.
+    await runtime.listMobileSessionTabs(`id:${TEST_WORKTREE_ID}`)
+    setSession({
+      ...getSession(),
+      tabsByWorktree: { [TEST_WORKTREE_ID]: [] },
+      terminalLayoutsByTabId: {}
+    })
+
+    await runtime.closeMobileSessionTab(`id:${TEST_WORKTREE_ID}`, 'host-tab')
+
+    expect(kill).toHaveBeenCalledWith('pty-a')
+    expect(kill).toHaveBeenCalledWith('pty-b')
+    const relisted = await runtime.listMobileSessionTabs(`id:${TEST_WORKTREE_ID}`)
+    expect(
+      relisted.tabs.filter((tab) => tab.type === 'terminal' && tab.parentTabId === 'host-tab')
+    ).toEqual([])
+  })
+
   it('closes persisted headless terminal parents before any prior list call', async () => {
     const { runtimeStore, getSession } = makeRuntimeStoreWithWorkspaceSession(
       makeWorkspaceSessionWithHeadlessTerminal()
diff --git a/src/main/runtime/orca-runtime.ts b/src/main/runtime/orca-runtime.ts
index 6e81da239cef..173bb9b4dc23 100644
--- a/src/main/runtime/orca-runtime.ts
+++ b/src/main/runtime/orca-runtime.ts
@@ -7285,11 +7285,7 @@ export class OrcaRuntimeService {
     }
   }
 
-  private removePersistedHeadlessTerminalTab(
-    worktreeId: string,
-    parentTabId: string,
-    options: { allowMissing?: boolean } = {}
-  ): string[] {
+  private removePersistedHeadlessTerminalTab(worktreeId: string, parentTabId: string): string[] {
     const session = this.getWorkspaceSessionForWorktree(worktreeId)
     if (!session || !this.store?.setWorkspaceSession) {
       throw new Error('workspace_session_unavailable')
@@ -7299,10 +7295,12 @@ export class OrcaRuntimeService {
       throw new Error('terminal_tab_pinned')
     }
     if (!result.closed) {
-      if (options.allowMissing) {
-        return []
-      }
-      throw new Error('tab_not_found')
+      // Why: the caller resolved the tab from the live snapshot, so a missing
+      // persisted row is always drift (never-persisted background tab, or an
+      // earlier close that de-persisted then failed). Aborting here would skip
+      // the PTY kill and snapshot prune below and the republished snapshot
+      // would resurrect the tab on every client forever (#10747, #12920).
+      return []
     }
     this.setWorkspaceSessionForWorktree(
       worktreeId,
@@ -7927,10 +7925,7 @@ export class OrcaRuntimeService {
           this.isRuntimeOwnedHeadlessMobileTab(worktreeId, remainingTab)
         ) {
           // Why: after relay recovery the renderer can acknowledge a tab it no longer mirrors; the HUB must still retire its SSH-owned surface.
-          this.closeHeadlessMobileTerminalTab(worktreeId, remainingSnapshot, remainingTab, {
-            // Why: the renderer may already have durably removed the tab before acknowledging.
-            allowMissingPersistedTab: true
-          })
+          this.closeHeadlessMobileTerminalTab(worktreeId, remainingSnapshot, remainingTab)
           this.notifyRendererOfHeadlessTerminalClose(tab.parentTabId)
           this.store?.flushOrThrow?.()
         }
@@ -8104,13 +8099,11 @@ export class OrcaRuntimeService {
     worktreeId: string,
     snapshot: RuntimeMobileSessionTabsSnapshot,
     tab: RuntimeMobileSessionTerminalTab,
-    options: { allowMissingPersistedTab?: boolean; killPtys?: boolean } = {}
+    options: { killPtys?: boolean } = {}
   ): void {
     const closedParentTabId = tab.parentTabId
     this.clearRuntimeSessionOwnershipForMobileTab(worktreeId, snapshot, closedParentTabId)
-    const projectedPtyIds = this.removePersistedHeadlessTerminalTab(worktreeId, closedParentTabId, {
-      allowMissing: options.allowMissingPersistedTab
-    })
+    const projectedPtyIds = this.removePersistedHeadlessTerminalTab(worktreeId, closedParentTabId)
     // Why: local provider ids can be reused after restart, so a dormant
     // persisted id is not kill authority. SSH relay ids remain durable exact
     // identities even before pane metadata reconnects.