diff --git a/apps/studio/components/interfaces/Explorer/__tests__/ExplorerNotebookTab.assistant-cache-invalidation.test.tsx b/apps/studio/components/interfaces/Explorer/__tests__/ExplorerNotebookTab.assistant-cache-invalidation.test.tsx
index 6762874a9b9..497d111046f 100644
--- a/apps/studio/components/interfaces/Explorer/__tests__/ExplorerNotebookTab.assistant-cache-invalidation.test.tsx
+++ b/apps/studio/components/interfaces/Explorer/__tests__/ExplorerNotebookTab.assistant-cache-invalidation.test.tsx
@@ -10,12 +10,15 @@ import {
   applyNotebookCacheEffects,
   collectNotebookCacheEffects,
 } from '@/lib/ai/notebook-cache-invalidation'
-import { createAssistantMessageWithUpdateNotebookTool } from '@/lib/ai/test-fixtures'
+import {
+  createAssistantMessageWithDeleteNotebookTool,
+  createAssistantMessageWithUpdateNotebookTool,
+} from '@/lib/ai/test-fixtures'
 import { notebooksState } from '@/state/notebooks/notebooks-state'
 import type { Notebook } from '@/state/notebooks/types'
 import { createTabsState, TabsStateContext } from '@/state/tabs'
 import { customRender } from '@/tests/lib/custom-render'
-import { addAPIMock } from '@/tests/lib/msw'
+import { addAPIMock, type APIErrorBody } from '@/tests/lib/msw'
 import { setupSqlEditorMocks } from '@/tests/lib/sql-editor-test-utils'
 
 const PROJECT_REF = 'default'
@@ -173,4 +176,33 @@ describe('ExplorerNotebookTab — assistant cache invalidation', () => {
     expect(await screen.findByText('Updated by assistant')).toBeInTheDocument()
     expect(screen.queryByText('Original content')).not.toBeInTheDocument()
   })
+
+  it('shows the not-found state after an assistant delete_notebook tool call completes', async () => {
+    setupSqlEditorMocks()
+    seedNotebook()
+
+    const queryClient = new QueryClient()
+    queryClient.setQueryData(contentKeys.resource(PROJECT_REF, NOTEBOOK_ID), { id: NOTEBOOK_ID })
+
+    addAPIMock({
+      method: 'get',
+      path: '/platform/projects/:ref/content/item/:id',
+      response: () =>
+        HttpResponse.json<APIErrorBody>({ message: 'Notebook not found' }, { status: 404 }),
+    })
+
+    renderNotebookTab(queryClient)
+
+    expect(await screen.findByText('Original content')).toBeInTheDocument()
+
+    const message = createAssistantMessageWithDeleteNotebookTool({
+      id: NOTEBOOK_ID,
+      name: 'Test notebook',
+    })
+    const effects = collectNotebookCacheEffects([message], new Set())
+    await applyNotebookCacheEffects({ queryClient, projectRef: PROJECT_REF, effects })
+
+    expect(await screen.findByText('Notebook not found')).toBeInTheDocument()
+    expect(screen.queryByText('Original content')).not.toBeInTheDocument()
+  })
 })
diff --git a/apps/studio/lib/ai/notebook-cache-invalidation.test.ts b/apps/studio/lib/ai/notebook-cache-invalidation.test.ts
index 5ece69aa63f..1b51c14642e 100644
--- a/apps/studio/lib/ai/notebook-cache-invalidation.test.ts
+++ b/apps/studio/lib/ai/notebook-cache-invalidation.test.ts
@@ -8,6 +8,7 @@ import {
 } from './notebook-cache-invalidation'
 import {
   createAssistantMessageWithCreateNotebookTool,
+  createAssistantMessageWithDeleteNotebookTool,
   createAssistantMessageWithUpdateNotebookTool,
   createAssistantTextMessage,
   createUserMessage,
@@ -50,6 +51,14 @@ describe('collectNotebookCacheEffects', () => {
     expect(effects).toEqual([{ _tag: 'upserted', toolCallId: 'call-notebook-1', id: 'notebook-1' }])
   })
 
+  it('collects a delete_notebook output-available part', () => {
+    const messages = [createAssistantMessageWithDeleteNotebookTool()]
+
+    const effects = collectNotebookCacheEffects(messages, new Set())
+
+    expect(effects).toEqual([{ _tag: 'deleted', toolCallId: 'call-notebook-1', id: 'notebook-1' }])
+  })
+
   it('ignores non-terminal tool states', () => {
     const messages = [
       assistantMessage([
@@ -138,6 +147,29 @@ describe('applyNotebookCacheEffects', () => {
     expect(notebooksState.notebooks[NOTEBOOK.id]).toBeUndefined()
   })
 
+  it('invalidates the nav list and evicts a deleted notebook from the cache', async () => {
+    notebooksState.setNotebook({ projectRef: PROJECT_REF, notebook: NOTEBOOK })
+    const queryClient = new QueryClient()
+    queryClient.setQueryData(contentKeys.resource(PROJECT_REF, NOTEBOOK.id), { id: NOTEBOOK.id })
+    queryClient.setQueryData(contentKeys.allContentLists(PROJECT_REF), [])
+    queryClient.setQueryData(contentKeys.infiniteList(PROJECT_REF), {})
+
+    await applyNotebookCacheEffects({
+      queryClient,
+      projectRef: PROJECT_REF,
+      effects: [{ _tag: 'deleted', toolCallId: 'call-1', id: NOTEBOOK.id }],
+    })
+
+    expect(queryClient.getQueryState(contentKeys.allContentLists(PROJECT_REF))?.isInvalidated).toBe(
+      true
+    )
+    expect(queryClient.getQueryState(contentKeys.infiniteList(PROJECT_REF))?.isInvalidated).toBe(
+      true
+    )
+    expect(queryClient.getQueryData(contentKeys.resource(PROJECT_REF, NOTEBOOK.id))).toBeUndefined()
+    expect(notebooksState.notebooks[NOTEBOOK.id]).toBeUndefined()
+  })
+
   it('leaves a dirty (unsaved) notebook in the store untouched', async () => {
     notebooksState.addNotebook({ projectRef: PROJECT_REF, notebook: NOTEBOOK })
     const queryClient = new QueryClient()
diff --git a/apps/studio/lib/ai/notebook-cache-invalidation.ts b/apps/studio/lib/ai/notebook-cache-invalidation.ts
index 8e990b13dee..cc40e3ba7db 100644
--- a/apps/studio/lib/ai/notebook-cache-invalidation.ts
+++ b/apps/studio/lib/ai/notebook-cache-invalidation.ts
@@ -10,10 +10,14 @@ export type NotebookCacheEffect =
   | { _tag: 'upserted'; toolCallId: string; id: string }
   | { _tag: 'deleted'; toolCallId: string; id: string }
 
-const NOTEBOOK_UPSERT_TOOL_TYPES = new Set(['tool-create_notebook', 'tool-update_notebook'])
+const NOTEBOOK_MUTATION_TOOL_TYPES = new Set([
+  'tool-create_notebook',
+  'tool-update_notebook',
+  'tool-delete_notebook',
+])
 
-function isNotebookUpsertPart(part: UIMessage['parts'][number]): part is ToolUIPart {
-  return NOTEBOOK_UPSERT_TOOL_TYPES.has(part.type)
+function isNotebookMutationPart(part: UIMessage['parts'][number]): part is ToolUIPart {
+  return NOTEBOOK_MUTATION_TOOL_TYPES.has(part.type)
 }
 
 export function collectNotebookCacheEffects(
@@ -26,14 +30,18 @@ export function collectNotebookCacheEffects(
     if (message.role !== 'assistant') continue
 
     for (const part of message.parts ?? []) {
-      if (!isNotebookUpsertPart(part)) continue
+      if (!isNotebookMutationPart(part)) continue
       if (part.state !== 'output-available') continue
       if (processed.has(part.toolCallId)) continue
 
       const result = notebookToolOutputSchema.safeParse(part.output)
       if (!result.success) continue
 
-      effects.push({ _tag: 'upserted', toolCallId: part.toolCallId, id: result.data.id })
+      effects.push({
+        _tag: part.type === 'tool-delete_notebook' ? 'deleted' : 'upserted',
+        toolCallId: part.toolCallId,
+        id: result.data.id,
+      })
     }
   }
 
diff --git a/apps/studio/lib/ai/test-fixtures.ts b/apps/studio/lib/ai/test-fixtures.ts
index 79500ae4d98..46db994a2a7 100644
--- a/apps/studio/lib/ai/test-fixtures.ts
+++ b/apps/studio/lib/ai/test-fixtures.ts
@@ -95,6 +95,28 @@ export function createAssistantMessageWithCreateNotebookTool(
   }
 }
 
+export function createAssistantMessageWithDeleteNotebookTool(
+  output: Record<string, unknown> = {
+    id: 'notebook-1',
+    name: 'Signup funnel',
+  },
+  id = 'assistant-notebook-msg-1'
+): UIMessage {
+  return {
+    id,
+    role: 'assistant',
+    parts: [
+      {
+        type: 'tool-delete_notebook',
+        state: 'output-available',
+        toolCallId: 'call-notebook-1',
+        input: { id: 'notebook-1' },
+        output,
+      } satisfies ToolUIPart,
+    ],
+  }
+}
+
 export function createAssistantMessageWithMultipleTools(
   id = 'assistant-multi-tool-msg-1'
 ): UIMessage {