diff --git a/src/main/runtime/orca-runtime.test.ts b/src/main/runtime/orca-runtime.test.ts
index 806349b39df..ba20f682015 100644
--- a/src/main/runtime/orca-runtime.test.ts
+++ b/src/main/runtime/orca-runtime.test.ts
@@ -19722,11 +19722,9 @@ describe('OrcaRuntimeService', () => {
     expect(getSession().terminalLayoutsByTabId['host-tab']).toBeUndefined()
   })
 
-  it('tears down a runtime-owned SSH headless tab authoritatively even when the renderer relay is wired', async () => {
-    // #8958 regression: with a window attached, both closeTerminal and
-    // closeTerminalTab are wired. A headless SSH tab is absent from the window
-    // graph, so the closeTerminalTab relay would resolve nothing and ack success
-    // while the PTY kept running. The authoritative teardown must win.
+  it('durably tears down a runtime-owned SSH headless tab when renderer cleanup fails', async () => {
+    // #8958 regression: the acknowledged renderer relay cannot see headless tabs;
+    // its advisory fallback must not prevent authoritative teardown or flushing.
     const persistedPtyId = 'ssh:ssh-1@@relay-pty'
     const { runtimeStore, getSession } = makeRuntimeStoreWithWorkspaceSession(
       makeWorkspaceSessionWithHeadlessTerminal({
@@ -19750,9 +19748,14 @@ describe('OrcaRuntimeService', () => {
       })
     )
     const kill = vi.fn(() => true)
-    const closeTerminal = vi.fn()
+    const flushOrThrow = vi.fn()
+    const rendererError = new Error('renderer unavailable')
+    const closeTerminal = vi.fn(() => {
+      throw rendererError
+    })
+    const warn = vi.spyOn(console, 'warn').mockImplementation(() => {})
     const closeTerminalTab = vi.fn(async () => {})
-    const runtime = new OrcaRuntimeService(runtimeStore as never)
+    const runtime = new OrcaRuntimeService({ ...runtimeStore, flushOrThrow } as never)
     runtime.setPtyController({
       write: () => true,
       kill,
@@ -19767,6 +19770,11 @@ describe('OrcaRuntimeService', () => {
     expect(closeTerminalTab).not.toHaveBeenCalled()
     expect(kill).toHaveBeenCalledWith(persistedPtyId)
     expect(closeTerminal).toHaveBeenCalledWith('host-tab')
+    expect(flushOrThrow).toHaveBeenCalledTimes(1)
+    expect(warn).toHaveBeenCalledWith(
+      '[runtime] failed to notify renderer after headless terminal close',
+      { parentTabId: 'host-tab', error: rendererError }
+    )
     expect(getSession().tabsByWorktree[TEST_WORKTREE_ID]).toEqual([])
     expect(getSession().terminalLayoutsByTabId['host-tab']).toBeUndefined()
   })
diff --git a/src/main/runtime/orca-runtime.ts b/src/main/runtime/orca-runtime.ts
index 556bc962ac9..fdf3657e08e 100644
--- a/src/main/runtime/orca-runtime.ts
+++ b/src/main/runtime/orca-runtime.ts
@@ -4692,7 +4692,7 @@ export class OrcaRuntimeService {
       // renderer's live pin guard and durable close transaction.
       if (closingWholeParent && !this.tabs.has(tab.parentTabId)) {
         this.closeHeadlessMobileTerminalTab(worktreeId, snapshot!, tab)
-        this.notifier?.closeTerminal(tab.parentTabId)
+        this.notifyRendererOfHeadlessTerminalClose(tab.parentTabId)
         this.store?.flushOrThrow?.()
         return { closed: true }
       }
@@ -4706,7 +4706,7 @@ export class OrcaRuntimeService {
       // only raw pane close. Runtime-owned parents still need de-persist + kill.
       if (closingWholeParent && this.isRuntimeOwnedHeadlessMobileTab(worktreeId, tab)) {
         this.closeHeadlessMobileTerminalTab(worktreeId, snapshot!, tab)
-        this.notifier?.closeTerminal(tab.parentTabId)
+        this.notifyRendererOfHeadlessTerminalClose(tab.parentTabId)
         this.store?.flushOrThrow?.()
         return { closed: true }
       }
@@ -4739,6 +4739,19 @@ export class OrcaRuntimeService {
     return { closed: true }
   }
 
+  private notifyRendererOfHeadlessTerminalClose(parentTabId: string): void {
+    // Why: this relay is advisory after main owns teardown; renderer failure must
+    // not prevent the authoritative session flush or turn the close into failure.
+    try {
+      this.notifier?.closeTerminal(parentTabId)
+    } catch (error) {
+      console.warn('[runtime] failed to notify renderer after headless terminal close', {
+        parentTabId,
+        error
+      })
+    }
+  }
+
   private async closeHeadlessMobileBrowserTab(
     worktreeId: string,
     snapshot: RuntimeMobileSessionTabsSnapshot,