From ab1ed8ea017566737ab227f37946b4e1831117c8 Mon Sep 17 00:00:00 2001
From: Gabriel Luiz Freitas Almeida <gabriel@langflow.org>
Date: Thu, 12 Jun 2025 09:51:18 -0300
Subject: [PATCH] docs: add comprehensive cursor guidelines and rules for
 development practices (#8401)

* Update cursor rules with specific backend, frontend, docs

* Update image example

Co-authored-by: coderabbitai[bot] <136622811+coderabbitai[bot]@users.noreply.github.com>

* update image example

Co-authored-by: coderabbitai[bot] <136622811+coderabbitai[bot]@users.noreply.github.com>

* Refactor frontend development guidelines: streamline sections, remove outdated icon development instructions, and update checklist for clarity and consistency.

---------

Co-authored-by: coderabbitai[bot] <136622811+coderabbitai[bot]@users.noreply.github.com>
---
 .cursor/rules/backend_development.mdc        | 268 +++++++++
 .cursor/rules/components/basic_component.mdc |   8 +-
 .cursor/rules/docs_development.mdc           | 440 +++++++++++++++
 .cursor/rules/frontend_development.mdc       | 374 +++++++++++++
 .cursor/rules/icons.mdc                      |  36 +-
 .cursor/rules/testing.mdc                    | 561 +++++++++++++++++++
 6 files changed, 1670 insertions(+), 17 deletions(-)
 create mode 100644 .cursor/rules/backend_development.mdc
 create mode 100644 .cursor/rules/docs_development.mdc
 create mode 100644 .cursor/rules/frontend_development.mdc
 create mode 100644 .cursor/rules/testing.mdc

diff --git a/.cursor/rules/backend_development.mdc b/.cursor/rules/backend_development.mdc
new file mode 100644
index 000000000..3ed0261f9
--- /dev/null
+++ b/.cursor/rules/backend_development.mdc
@@ -0,0 +1,268 @@
+---
+description: "Guidelines for backend development in Langflow, focusing on Python components, FastAPI services, and backend testing."
+globs:
+  - "src/backend/**/*.py"
+  - "tests/**/*.py"
+  - "Makefile"
+  - "pyproject.toml"
+  - "uv.lock"
+alwaysApply: false
+---
+
+
+# Backend Development Guidelines
+
+## Purpose
+Guidelines for backend development in Langflow, focusing on Python components, FastAPI services, and backend testing.
+
+---
+
+## 1. Backend Environment Setup
+
+### Prerequisites
+- **Python Package Manager:** `uv` (>=0.4) for dependency management
+- **Database:** SQLite for development, PostgreSQL for production
+- **Development Tools:** `make` for build coordination
+
+### Backend Service
+```bash
+make backend  # Start FastAPI backend on port 7860
+```
+- Auto-reloads on file changes
+- Health check: http://localhost:7860/health
+- Backend components: `src/backend/base/langflow/`
+
+---
+
+## 2. Component Development
+
+### Component Structure
+```
+src/backend/base/langflow/components/
+├── agents/           # Agent components
+├── data/            # Data processing components
+├── embeddings/      # Embedding components
+├── input_output/    # Input/output components
+├── models/          # Language model components
+├── processing/      # Text processing components
+├── prompts/         # Prompt components
+├── tools/           # Tool components
+└── vectorstores/    # Vector store components
+```
+
+### Adding New Components
+1. **Location:** Add to appropriate subdirectory under `src/backend/base/langflow/components/`
+2. **Import:** Update `__init__.py` with alphabetical imports:
+   ```python
+   from .my_component import MyComponent
+
+   __all__ = [
+       "ExistingComponent",
+       "MyComponent",  # Add alphabetically
+   ]
+   ```
+3. **Auto-restart:** Backend auto-restarts on save
+4. **Browser refresh:** Refresh browser to see component changes
+
+### Component Testing
+- **Unit Tests:** `src/backend/tests/unit/components/`
+- **Test Structure:** Mirror component directory structure
+- **Test Base Classes:** Use `ComponentTestBaseWithClient` or `ComponentTestBaseWithoutClient`
+- **Version Testing:** Provide `file_names_mapping` for backward compatibility
+
+### Development Tips
+- **Fast iteration:** Edit component in UI first, then save to source
+- **Component updates:** Old components show "Updates Available" after backend restart
+- **Testing:** Create comprehensive unit tests for all new components
+
+---
+
+## 3. Backend Code Quality
+
+### Formatting (CRITICAL)
+```bash
+make format_backend  # Format Python code
+```
+**Important:** Run `make format_backend` _early and often_ (ideally before running linting or committing changes). It auto-corrects the majority of style issues, preventing lengthy manual fixes when lint errors surface later.
+
+### Linting
+```bash
+make lint  # Run linting checks
+```
+
+### Testing
+```bash
+make unit_tests  # Run backend unit tests
+```
+
+### Pre-commit Workflow
+1. **Run `make format_backend`** (FIRST - saves time on lint fixes)
+2. Run `make lint`
+3. Run `make unit_tests`
+4. Commit changes
+
+---
+
+## 4. FastAPI Development
+
+### API Structure
+```
+src/backend/base/langflow/api/
+├── v1/              # API version 1
+│   ├── chat.py      # Chat endpoints
+│   ├── flows.py     # Flow management
+│   ├── users.py     # User management
+│   └── ...
+└── v2/              # API version 2 (future)
+```
+
+### Testing APIs
+- Use `client` fixture from `conftest.py`
+- Test with `logged_in_headers` for authenticated endpoints
+- Example:
+  ```python
+  async def test_flows_endpoint(client, logged_in_headers):
+      response = await client.post(
+          "api/v1/flows/",
+          json=flow_data,
+          headers=logged_in_headers
+      )
+      assert response.status_code == 201
+  ```
+
+---
+
+## 5. Database Development
+
+### Models Location
+```
+src/backend/base/langflow/services/database/models/
+├── api_key/         # API key models
+├── flow/            # Flow models
+├── folder/          # Folder models
+├── user/            # User models
+└── ...
+```
+
+### Database Testing
+- Use in-memory SQLite for tests
+- Database tests may fail in batch runs - run individually if needed:
+  ```bash
+  uv run pytest src/backend/tests/unit/test_database.py
+  ```
+
+---
+
+## 6. Async Development Patterns
+
+### Component Async Methods
+```python
+async def run(self) -> MessageType:
+    """Main component execution method."""
+    # Use await for async operations
+    result = await self.async_operation()
+    return result
+
+async def message_response(self) -> Message:
+    """Return a Message object for chat components."""
+    return Message(
+        text=self.input_value,
+        sender=self.sender,
+        session_id=self.session_id,
+    )
+```
+
+### Background Tasks
+```python
+import asyncio
+
+async def process_in_background(self):
+    """Process items without blocking."""
+    # Use asyncio.create_task for background work
+    task = asyncio.create_task(self.heavy_operation())
+
+    # Ensure proper cleanup
+    try:
+        result = await task
+        return result
+    except asyncio.CancelledError:
+        # Handle cancellation gracefully
+        await self.cleanup()
+        raise
+```
+
+### Queue Operations
+```python
+async def queue_processing(self):
+    """Non-blocking queue operations."""
+    queue = asyncio.Queue()
+
+    # Non-blocking put
+    queue.put_nowait(data)
+
+    # Timeout-controlled get
+    try:
+        result = await asyncio.wait_for(queue.get(), timeout=5.0)
+        return result
+    except asyncio.TimeoutError:
+        # Handle timeout appropriately
+        raise ComponentError("Processing timeout")
+```
+
+---
+
+## 7. Component Integration Testing
+
+### Flow Testing
+```python
+from tests.unit.build_utils import create_flow, build_flow, get_build_events
+
+async def test_component_in_flow(client, json_flow, logged_in_headers):
+    """Test component within a complete flow."""
+    flow_id = await create_flow(client, json_flow, logged_in_headers)
+    build_response = await build_flow(client, flow_id, logged_in_headers)
+
+    # Validate flow execution
+    job_id = build_response["job_id"]
+    events_response = await get_build_events(client, job_id, logged_in_headers)
+    assert events_response.status_code == 200
+```
+
+### External API Testing
+```python
+@pytest.mark.api_key_required
+@pytest.mark.no_blockbuster
+async def test_with_real_api(self):
+    """Test component with external service."""
+    api_key = os.getenv("OPENAI_API_KEY")
+    component = MyComponent(api_key=api_key, model="gpt-4o")
+
+    response = await component.run()
+    assert response is not None
+```
+
+---
+
+## 8. Known Backend Issues
+
+### Testing Quirks
+- `test_database.py` may fail in batch runs but pass individually
+- Use `@pytest.mark.no_blockbuster` to skip blockbuster plugin when needed
+- Context variables may not propagate correctly in `asyncio.to_thread` - test both patterns
+
+### File Changes
+- Starter project files auto-format after `langflow run`
+- These formatting changes can be committed or ignored
+
+---
+
+## Backend Development Checklist
+- [ ] Component added to appropriate subdirectory
+- [ ] `__init__.py` updated with alphabetical imports
+- [ ] Code formatted with `make format_backend` (FIRST)
+- [ ] Linting passed with `make lint`
+- [ ] Unit tests created and passing with `make unit_tests`
+- [ ] Component tested in UI with backend restart + browser refresh
+- [ ] Version mapping provided for backward compatibility
+- [ ] Async patterns implemented correctly with proper cleanup
+- [ ] External API calls use appropriate pytest markers
diff --git a/.cursor/rules/components/basic_component.mdc b/.cursor/rules/components/basic_component.mdc
index 98fcb60db..f2cb445de 100644
--- a/.cursor/rules/components/basic_component.mdc
+++ b/.cursor/rules/components/basic_component.mdc
@@ -1,8 +1,12 @@
 ---
-description: Rules and checklist for creating a basic Langflow Component
-globs: 
+description: "Guide for creating a basic Langflow component, including requirements gathering, component structure, and implementation best practices."
+globs:
+  - "src/backend/**/components/**/*.py"
+  - "src/backend/base/langflow/components/**/*.py"
 alwaysApply: false
 ---
+
+
 # Rule: How to Create a Basic Langflow Component
 
 ## Purpose
diff --git a/.cursor/rules/docs_development.mdc b/.cursor/rules/docs_development.mdc
new file mode 100644
index 000000000..6e694f01b
--- /dev/null
+++ b/.cursor/rules/docs_development.mdc
@@ -0,0 +1,440 @@
+---
+description: "Guidelines for developing and maintaining Langflow documentation using Docusaurus, including content structure, style, and deployment processes."
+globs:
+  - "docs/**/*.{md,mdx}"
+  - "docs/**/*.{js,jsx,ts,tsx}"
+  - "docs/package*.json"
+  - "docs/docusaurus.config.js"
+  - "docs/sidebars.js"
+  - "docs/static/**/*"
+alwaysApply: false
+---
+
+
+# Documentation Development Guidelines
+
+## Purpose
+Guidelines for developing and maintaining Langflow documentation using Docusaurus, including content structure, style, and deployment processes.
+
+---
+
+## 1. Documentation Environment Setup
+
+### Prerequisites
+- **Node.js:** v22.12 LTS for runtime
+- **Package Manager:** Yarn for dependency management
+- **Documentation Framework:** Docusaurus v3
+
+### Documentation Service
+```bash
+cd docs
+yarn install      # Install dependencies
+yarn start        # Start dev server (usually port 3001)
+```
+- Auto-reloads on documentation changes
+- Access at: http://localhost:3001/
+- Documentation source: `docs/`
+
+---
+
+## 2. Documentation Structure
+
+### Directory Layout
+```
+docs/
+├── docs/                    # Main documentation content
+│   ├── getting-started/     # Getting started guides
+│   ├── components/          # Component documentation
+│   ├── integrations/        # Third-party integrations
+│   ├── administration/      # Admin and deployment guides
+│   ├── contributing/        # Contribution guidelines
+│   └── api-reference/       # API documentation
+├── blog/                    # Blog posts and announcements
+├── src/                     # Custom React components
+├── static/                  # Static assets (images, etc.)
+├── sidebars.js             # Sidebar configuration
+├── docusaurus.config.js    # Main configuration
+└── package.json            # Dependencies
+```
+
+### Content Types
+- **Guides:** Step-by-step tutorials (`docs/getting-started/`)
+- **Reference:** API and component reference (`docs/api-reference/`)
+- **How-to:** Problem-solving articles (`docs/components/`)
+- **Concepts:** Explanatory articles about Langflow concepts
+- **Blog:** Release notes, announcements (`blog/`)
+
+---
+
+## 3. Writing Documentation
+
+### Markdown Conventions
+```markdown
+---
+title: Page Title
+description: Brief description for SEO
+sidebar_position: 1
+---
+
+# Page Title
+
+Brief introduction paragraph.
+
+## Section Header
+
+Content with proper formatting.
+
+### Subsection
+
+More detailed content.
+
+:::tip
+Use admonitions for important information.
+:::
+
+:::warning
+Use warnings for potential issues.
+:::
+
+:::danger
+Use danger for critical warnings.
+:::
+```
+
+### Code Blocks
+````markdown
+```python title="component_example.py"
+from langflow.components.base import Component
+
+class MyComponent(Component):
+    display_name = "My Component"
+    description = "Example component"
+
+    def run(self):
+        return "Hello, World!"
+```
+````
+
+### Images and Assets
+```markdown
+<!-- Images go in static/img/ -->
+![Component Overview](/img/components/overview.png)
+
+<!-- Use descriptive alt text -->
+![Langflow interface showing the flow editor with nodes and connections](/img/flow-editor.png)
+```
+
+---
+
+## 4. Component Documentation
+
+### Component Page Template
+```markdown
+---
+title: Component Name
+description: Brief description of what the component does
+sidebar_position: 1
+---
+
+# Component Name
+
+Brief overview of the component's purpose.
+
+## Overview
+
+What this component does and when to use it.
+
+## Configuration
+
+### Inputs
+
+| Input | Type | Required | Description |
+|-------|------|----------|-------------|
+| `input_text` | String | Yes | The text to process |
+| `model_name` | String | No | Model to use (default: gpt-3.5-turbo) |
+
+### Outputs
+
+| Output | Type | Description |
+|--------|------|-------------|
+| `result` | Message | Processed result |
+
+## Usage Example
+
+```python
+# Example of using the component
+component = MyComponent(
+    input_text="Hello, world!",
+    model_name="gpt-4"
+)
+result = component.run()
+```
+
+## Common Issues
+
+### Issue: Component not loading
+
+**Solution:** Check that all required inputs are provided.
+
+### Issue: API key errors
+
+**Solution:** Ensure your API key is properly configured.
+```
+
+### API Documentation
+```markdown
+---
+title: API Endpoint
+description: REST API endpoint documentation
+---
+
+# API Endpoint Name
+
+## Endpoint
+
+`POST /api/v1/endpoint`
+
+## Request
+
+### Headers
+```json
+{
+  "Authorization": "Bearer <token>",
+  "Content-Type": "application/json"
+}
+```
+
+### Body
+```json
+{
+  "parameter": "value",
+  "optional_param": "optional_value"
+}
+```
+
+## Response
+
+### Success (200)
+```json
+{
+  "success": true,
+  "data": {
+    "result": "success"
+  }
+}
+```
+
+### Error (400)
+```json
+{
+  "success": false,
+  "error": "Error message"
+}
+```
+
+## Example
+
+```bash
+curl -X POST http://localhost:7860/api/v1/endpoint \
+  -H "Authorization: Bearer your-token" \
+  -H "Content-Type: application/json" \
+  -d '{"parameter": "value"}'
+```
+```
+
+---
+
+## 5. Blog Posts and Announcements
+
+### Blog Post Template
+```markdown
+---
+title: "Release: Langflow v1.1.0"
+description: "New features and improvements in Langflow v1.1.0"
+authors: [author-name]
+date: 2024-01-15
+tags: [release, features]
+---
+
+# Release: Langflow v1.1.0
+
+Brief introduction to the release.
+
+## New Features
+
+### Feature 1
+Description of the feature and how to use it.
+
+### Feature 2
+Another feature description.
+
+## Improvements
+
+- List of improvements
+- Bug fixes
+- Performance enhancements
+
+## Breaking Changes
+
+:::warning
+List any breaking changes that require user action.
+:::
+
+## Migration Guide
+
+Steps to migrate from previous versions.
+```
+
+### Announcement Posts
+```markdown
+---
+title: "Announcement: New Integration"
+description: "Langflow now supports integration with XYZ service"
+authors: [author-name]
+date: 2024-01-15
+tags: [announcement, integration]
+---
+
+Brief announcement content with clear call-to-action.
+```
+
+---
+
+## 6. Configuration
+
+### Sidebar Configuration (`sidebars.js`)
+```javascript
+module.exports = {
+  docs: [
+    'introduction',
+    {
+      type: 'category',
+      label: 'Getting Started',
+      items: [
+        'getting-started/installation',
+        'getting-started/quickstart',
+        'getting-started/first-flow',
+      ],
+    },
+    {
+      type: 'category',
+      label: 'Components',
+      items: [
+        'components/overview',
+        'components/inputs',
+        'components/outputs',
+        'components/processing',
+      ],
+    },
+  ],
+};
+```
+
+### Site Configuration (`docusaurus.config.js`)
+```javascript
+module.exports = {
+  title: 'Langflow Documentation',
+  tagline: 'Build AI flows visually',
+  url: 'https://docs.langflow.org',
+  baseUrl: '/',
+
+  themeConfig: {
+    navbar: {
+      title: 'Langflow',
+      logo: {
+        alt: 'Langflow Logo',
+        src: 'img/logo.svg',
+      },
+      items: [
+        {
+          type: 'doc',
+          docId: 'introduction',
+          position: 'left',
+          label: 'Docs',
+        },
+        {
+          to: '/blog',
+          label: 'Blog',
+          position: 'left'
+        },
+      ],
+    },
+  },
+};
+```
+
+---
+
+## 7. Documentation Testing
+
+### Link Checking
+```bash
+# Check for broken internal links
+yarn build
+yarn serve
+# Manual testing or use link checker tools
+```
+
+### Content Review
+- **Accuracy:** Verify all code examples work
+- **Completeness:** Ensure all features are documented
+- **Clarity:** Review for clear, concise language
+- **Navigation:** Test sidebar and cross-references
+
+### Screenshots
+- Keep screenshots up-to-date with current UI
+- Use consistent browser/OS for screenshots
+- Highlight relevant UI elements
+- Use descriptive file names
+
+---
+
+## 8. Style Guide
+
+### Writing Style
+- **Tone:** Professional but approachable
+- **Voice:** Second person ("you") for instructions
+- **Tense:** Present tense for current features
+- **Length:** Keep paragraphs short and scannable
+
+### Formatting
+- **Headers:** Use sentence case
+- **Code:** Inline code with `backticks`
+- **Emphasis:** Use **bold** for UI elements, *italic* for emphasis
+- **Lists:** Use parallel structure
+
+### Terminology
+- **Langflow:** Always capitalize
+- **Component:** Capitalize when referring to Langflow components
+- **Flow:** Capitalize when referring to Langflow flows
+- **API:** Always uppercase
+- **JSON:** Always uppercase
+
+---
+
+## 9. Deployment
+
+### Local Testing
+```bash
+yarn build    # Build static site
+yarn serve    # Serve built site locally
+```
+
+### Production Deployment
+- Documentation is automatically deployed on commit to main branch
+- Build artifacts go to `build/` directory
+- Static site is served via CDN
+
+---
+
+## Documentation Development Checklist
+- [ ] Documentation service running with `yarn start`
+- [ ] Content follows markdown conventions
+- [ ] Code examples are tested and working
+- [ ] Images have descriptive alt text
+- [ ] Internal links are functional
+- [ ] Sidebar navigation is updated
+- [ ] Content follows style guide
+- [ ] Screenshots are current and properly formatted
+- [ ] Cross-references between related topics
+- [ ] Build succeeds with `yarn build`
diff --git a/.cursor/rules/frontend_development.mdc b/.cursor/rules/frontend_development.mdc
new file mode 100644
index 000000000..42b3dac7e
--- /dev/null
+++ b/.cursor/rules/frontend_development.mdc
@@ -0,0 +1,374 @@
+---
+description: "Guidelines for frontend development in Langflow, focusing on React/TypeScript UI components, build processes, and frontend testing."
+globs:
+  - "src/frontend/**/*.{ts,tsx,js,jsx}"
+  - "src/frontend/**/*.{css,scss,json}"
+  - "src/frontend/package*.json"
+  - "src/frontend/vite.config.*"
+  - "src/frontend/tailwind.config.*"
+  - "src/frontend/tsconfig.json"
+alwaysApply: false
+---
+
+## 1. Frontend Environment Setup
+
+### Prerequisites
+- **Node.js:** v22.12 LTS for JavaScript runtime
+- **Package Manager:** npm (v10.9) for dependency management
+- **Development Tools:** Vite for build tooling
+
+### Frontend Service
+```bash
+make frontend  # Start Vite dev server on port 3000
+```
+- Hot-reload enabled for UI changes
+- Access at: http://localhost:3000/
+- Frontend source: `src/frontend/`
+
+---
+
+## 2. Frontend Structure
+
+### Directory Layout
+```
+src/frontend/src/
+├── components/          # Reusable UI components
+├── pages/              # Page-level components
+├── icons/              # Component icons and lazy loading
+├── stores/             # State management (Zustand)
+├── types/              # TypeScript type definitions
+├── utils/              # Utility functions
+├── hooks/              # Custom React hooks
+├── services/           # API service functions
+└── assets/             # Static assets
+```
+
+### Key Technologies
+- **React 18** with TypeScript
+- **Vite** for build tooling and dev server
+- **Tailwind CSS** for styling
+- **Zustand** for state management
+- **React Flow** for flow graph visualization
+- **Lucide React** for icons
+
+---
+
+## 3. Frontend Code Quality
+
+### Formatting
+```bash
+make format_frontend  # Format TypeScript/JavaScript code
+```
+
+### Linting
+```bash
+make lint  # Run ESLint and TypeScript checks
+```
+
+### Testing
+```bash
+make tests_frontend  # Run frontend tests (requires additional setup)
+```
+
+### Pre-commit Workflow
+1. Run `make format_frontend`
+2. Run `make lint`
+3. Test changes in browser
+4. Commit changes
+
+---
+
+## 4. State Management
+
+### Zustand Stores
+```typescript
+// stores/myStore.ts
+import { create } from 'zustand';
+
+interface MyState {
+  value: string;
+  setValue: (value: string) => void;
+}
+
+export const useMyStore = create<MyState>((set) => ({
+  value: '',
+  setValue: (value) => set({ value }),
+}));
+```
+
+### Using Stores in Components
+```typescript
+// components/MyComponent.tsx
+import { useMyStore } from '@/stores/myStore';
+
+export function MyComponent() {
+  const { value, setValue } = useMyStore();
+
+  return (
+    <input
+      value={value}
+      onChange={(e) => setValue(e.target.value)}
+    />
+  );
+}
+```
+
+---
+
+## 5. API Integration
+
+### Service Functions
+```typescript
+// services/api.ts
+import { api } from '@/controllers/API';
+
+export async function createFlow(flowData: FlowData) {
+  const response = await api.post('/flows/', flowData);
+  return response.data;
+}
+
+export async function getFlows() {
+  const response = await api.get('/flows/');
+  return response.data;
+}
+```
+
+### Error Handling
+```typescript
+// hooks/useApi.ts
+import { useState, useCallback } from 'react';
+
+export function useApi<T>(apiFunction: (...args: any[]) => Promise<T>) {
+  const [loading, setLoading] = useState(false);
+  const [error, setError] = useState<string | null>(null);
+
+  const execute = useCallback(async (...args: any[]) => {
+    try {
+      setLoading(true);
+      setError(null);
+      const result = await apiFunction(...args);
+      return result;
+    } catch (err) {
+      setError(err instanceof Error ? err.message : 'Unknown error');
+      throw err;
+    } finally {
+      setLoading(false);
+    }
+  }, [apiFunction]);
+
+  return { execute, loading, error };
+}
+```
+
+---
+
+## 6. React Flow Integration
+
+### Flow Graph Components
+```typescript
+// components/FlowGraph.tsx
+import ReactFlow, {
+  Node,
+  Edge,
+  Controls,
+  Background
+} from 'reactflow';
+
+interface FlowGraphProps {
+  nodes: Node[];
+  edges: Edge[];
+  onNodesChange: (changes: NodeChange[]) => void;
+  onEdgesChange: (changes: EdgeChange[]) => void;
+}
+
+export function FlowGraph({
+  nodes,
+  edges,
+  onNodesChange,
+  onEdgesChange
+}: FlowGraphProps) {
+  return (
+    <div className="w-full h-full">
+      <ReactFlow
+        nodes={nodes}
+        edges={edges}
+        onNodesChange={onNodesChange}
+        onEdgesChange={onEdgesChange}
+        fitView
+      >
+        <Controls />
+        <Background />
+      </ReactFlow>
+    </div>
+  );
+}
+```
+
+### Custom Node Types
+```typescript
+// components/nodes/ComponentNode.tsx
+import { memo } from 'react';
+import { Handle, Position } from 'reactflow';
+
+interface ComponentNodeProps {
+  data: {
+    label: string;
+    icon?: string;
+  };
+}
+
+export const ComponentNode = memo(({ data }: ComponentNodeProps) => {
+  return (
+    <div className="px-4 py-2 shadow-md rounded-md bg-white border">
+      <Handle type="target" position={Position.Top} />
+
+      <div className="flex items-center">
+        {data.icon && (
+          <img src={data.icon} alt="" className="w-4 h-4 mr-2" />
+        )}
+        <span className="text-sm">{data.label}</span>
+      </div>
+
+      <Handle type="source" position={Position.Bottom} />
+    </div>
+  );
+});
+```
+
+---
+
+## 7. Styling with Tailwind
+
+### Component Styling
+```typescript
+// components/Button.tsx
+import { cn } from '@/utils/cn';
+
+interface ButtonProps {
+  variant?: 'primary' | 'secondary';
+  size?: 'sm' | 'md' | 'lg';
+  children: React.ReactNode;
+  onClick?: () => void;
+}
+
+export function Button({
+  variant = 'primary',
+  size = 'md',
+  children,
+  onClick
+}: ButtonProps) {
+  return (
+    <button
+      className={cn(
+        'rounded-md font-medium transition-colors',
+        {
+          'bg-blue-600 hover:bg-blue-700 text-white': variant === 'primary',
+          'bg-gray-200 hover:bg-gray-300 text-gray-900': variant === 'secondary',
+          'px-2 py-1 text-sm': size === 'sm',
+          'px-4 py-2 text-base': size === 'md',
+          'px-6 py-3 text-lg': size === 'lg',
+        }
+      )}
+      onClick={onClick}
+    >
+      {children}
+    </button>
+  );
+}
+```
+
+### Dark Mode Support
+```typescript
+// hooks/useDarkMode.ts
+import { useDarkStore } from '@/stores/darkStore';
+
+export function useDarkMode() {
+  const { dark, setDark } = useDarkStore();
+
+  const toggle = () => setDark(!dark);
+
+  return { isDark: dark, toggle };
+}
+```
+
+---
+
+## 8. Frontend Testing
+
+### Component Testing
+```typescript
+// __tests__/Button.test.tsx
+import { render, screen, fireEvent } from '@testing-library/react';
+import { Button } from '@/components/Button';
+
+describe('Button', () => {
+  it('renders with correct text', () => {
+    render(<Button>Click me</Button>);
+    expect(screen.getByText('Click me')).toBeInTheDocument();
+  });
+
+  it('calls onClick when clicked', () => {
+    const handleClick = jest.fn();
+    render(<Button onClick={handleClick}>Click me</Button>);
+
+    fireEvent.click(screen.getByText('Click me'));
+    expect(handleClick).toHaveBeenCalledTimes(1);
+  });
+});
+```
+
+### Integration Testing
+```typescript
+// __tests__/FlowEditor.test.tsx
+import { render, screen } from '@testing-library/react';
+import { FlowEditor } from '@/pages/FlowEditor';
+
+describe('FlowEditor', () => {
+  it('loads flow data correctly', async () => {
+    render(<FlowEditor flowId="test-flow-id" />);
+
+    // Wait for flow to load
+    await screen.findByText('Flow loaded');
+
+    expect(screen.getByTestId('flow-canvas')).toBeInTheDocument();
+  });
+});
+```
+
+---
+
+## 9. Build and Deployment
+
+### Development Build
+```bash
+make build_frontend  # Build frontend static files
+```
+
+### Production Build
+```bash
+cd src/frontend
+npm run build  # Creates dist/ directory
+```
+
+### Build Integration
+- Frontend builds to `src/frontend/dist/`
+- Backend serves static files from this directory in production
+- `make init` includes frontend build step
+---
+
+## Frontend Development Checklist
+- [ ] Frontend service running with `make frontend`
+- [ ] Changes hot-reload correctly in browser
+- [ ] State management uses Zustand stores
+- [ ] API calls use proper error handling
+- [ ] Components styled with Tailwind CSS
+- [ ] Dark mode support implemented where needed
+- [ ] Code formatted with `make format_frontend`
+- [ ] Linting passed with `make lint`
+- [ ] Changes tested in both light and dark mode
+
+- [ ] Components styled with Tailwind CSS
+- [ ] Dark mode support implemented where needed
+- [ ] Code formatted with `make format_frontend`
+- [ ] Changes tested in both light and dark mode
+
diff --git a/.cursor/rules/icons.mdc b/.cursor/rules/icons.mdc
index 5d46a2b8f..30a7550dd 100644
--- a/.cursor/rules/icons.mdc
+++ b/.cursor/rules/icons.mdc
@@ -1,8 +1,14 @@
 ---
-description: Rules and checklist for adding and using langflow component icons.
-globs: 
+description: "Rules for creating and implementing component icons in Langflow, covering both backend Python component icon attributes and frontend React icon implementation."
+globs:
+  - "src/frontend/src/icons/**/*"
+  - "src/frontend/src/icons/lazyIconImports.ts"
+  - "src/backend/**/*component*.py"
+  - "src/backend/**/components/**/*.py"
 alwaysApply: false
 ---
+
+
 # Component Icon Rules
 
 ## Purpose
@@ -13,12 +19,12 @@ To ensure consistent, clear, and functional icon usage for components, covering
 ## 1. Backend (Python) — Setting the Icon Name
 
 - **Where:** In your component class (e.g., in `src/backend/base/langflow/components/vectorstores/astradb.py`)
-- **How:**  
+- **How:**
   Set the `icon` attribute to a string matching the icon you want to use.
   ```python
   icon = "AstraDB"
   ```
-- **Tip:**  
+- **Tip:**
   The string must match the frontend icon mapping exactly (case-sensitive).
 
 ---
@@ -27,9 +33,9 @@ To ensure consistent, clear, and functional icon usage for components, covering
 
 ### a. Create the Icon Component
 
-- **Where:**  
+- **Where:**
   In a new directory for your icon, e.g., `src/frontend/src/icons/AstraDB/`.
-- **How:**  
+- **How:**
   - Add your SVG as a React component, e.g., `AstraSVG` in `AstraDB.jsx`.
     ```jsx
     const AstraSVG = (props) => (
@@ -74,28 +80,28 @@ To ensure consistent, clear, and functional icon usage for components, covering
 
 ### b. Add to Lazy Icon Imports
 
-- **Where:**  
+- **Where:**
   In `src/frontend/src/icons/lazyIconImports.ts`
-- **How:**  
+- **How:**
   Add an entry to the `lazyIconsMapping` object:
   ```ts
   AstraDB: () =>
     import("@/icons/AstraDB").then((mod) => ({ default: mod.AstraDBIcon })),
   ```
-- **Tip:**  
+- **Tip:**
   The key (`AstraDB`) must match the string used in the backend.
 
 ---
 
 ## 3. Best Practices
 
-- **Naming:**  
+- **Naming:**
   Use clear, recognizable names (e.g., `"AstraDB"`, `"Postgres"`, `"OpenAI"`).
-- **Consistency:**  
+- **Consistency:**
   Always use the same icon name for the same service across backend and frontend.
-- **Missing Icon:**  
+- **Missing Icon:**
   If no icon exists, use a [lucide icon](https://lucide.dev/icons)
-- **Light/Dark Mode:**  
+- **Light/Dark Mode:**
   Always support both light and dark mode for custom icons by using the `isdark` prop in your SVG.
 
 ---
@@ -114,11 +120,11 @@ To ensure consistent, clear, and functional icon usage for components, covering
 ---
 
 **Example for AstraDB:**
-- Backend:  
+- Backend:
   ```python
   icon = "AstraDB"
   ```
-- Frontend:  
+- Frontend:
   - `src/icons/AstraDB/AstraDB.jsx` (SVG as React component, uses `isdark` prop)
   - `src/icons/AstraDB/index.tsx` (exports `AstraDBIcon` and passes `isdark`)
   - Add to `lazyIconImports.ts`:
diff --git a/.cursor/rules/testing.mdc b/.cursor/rules/testing.mdc
new file mode 100644
index 000000000..1bd0af1cf
--- /dev/null
+++ b/.cursor/rules/testing.mdc
@@ -0,0 +1,561 @@
+---
+description: "Guidelines for testing Langflow components and backend code, with emphasis on async patterns and robust, well-documented testing practices."
+globs:
+  - "src/backend/tests/**/*.py"
+  - "src/frontend/**/*.test.{ts,tsx,js,jsx}"
+  - "src/frontend/**/*.spec.{ts,tsx,js,jsx}"
+  - "tests/**/*.py"
+  - "conftest.py"
+  - "pytest.ini"
+alwaysApply: false
+---
+
+# Testing Guidelines for Langflow
+
+## Purpose
+Guidelines for testing Langflow components and backend code, with emphasis on async patterns and robust, well-documented testing practices.
+
+---
+
+## 1. Testing Structure
+
+### Backend Tests Location
+- **Unit Tests:** `src/backend/tests/`
+- **Component Tests:** `src/backend/tests/unit/components/` (organized by component subdirectory)
+- **Integration Tests:** Available via `make integration_tests` (requires additional setup)
+
+### Test File Naming
+- Use same filename as component with appropriate test prefix/suffix
+- Example: `my_component.py` → `test_my_component.py`
+
+---
+
+## 2. Built-in Fixtures & Base Classes
+
+### `client` Fixture (FastAPI Test Client)
+- Defined in `src/backend/tests/conftest.py`
+- Provides an **async** `httpx.AsyncClient` connected to the full application via `ASGITransport` + `LifespanManager`.
+- Use it for API tests:
+  ```python
+  async def test_login_endpoint(client):
+      response = await client.post("api/v1/login", data={"username": "foo", "password": "bar"})
+      assert response.status_code == 200
+  ```
+- Automatically configured with an **in-memory SQLite database** and mocked environment variables. No additional setup needed in individual tests.
+- Skip client creation by marking the test with `@pytest.mark.noclient`.
+
+### `ComponentTestBase` Family
+Located in `src/backend/tests/base.py`.
+
+| Base Class | Creates `client`? | Typical Use | Notes |
+|------------|------------------|-------------|-------|
+| `ComponentTestBase` | No | Core logic for component version testing | Requires you to provide fixtures described below. |
+| `ComponentTestBaseWithClient` | Yes (`@pytest.mark.usefixtures("client")`) | Components that need API access during `run()` | Inherit when the component interacts with backend services. |
+| `ComponentTestBaseWithoutClient` | No | Pure-logic components with no API calls | Lightweight alternative. |
+
+Required fixtures for subclasses:
+1. `component_class` → the component **class** under test.
+2. `default_kwargs` → dict of kwargs to instantiate the component (can be empty).
+3. `file_names_mapping` → list of `VersionComponentMapping` dicts mapping historical **Langflow versions** to module/file names.
+
+Example skeleton:
+```python
+from tests.base import ComponentTestBaseWithClient, VersionComponentMapping, DID_NOT_EXIST
+from langflow.components.my_namespace import MyComponent
+
+class TestMyComponent(ComponentTestBaseWithClient):
+    @pytest.fixture
+    def component_class(self):
+        return MyComponent
+
+    @pytest.fixture
+    def default_kwargs(self):
+        return {"foo": "bar"}
+
+    @pytest.fixture
+    def file_names_mapping(self):
+        return [
+            VersionComponentMapping(version="1.1.1", module="my_module", file_name="my_component.py"),
+            # Older versions can be mapped or DID_NOT_EXIST
+            VersionComponentMapping(version="1.0.19", module="my_module", file_name=DID_NOT_EXIST),
+        ]
+```
+
+`ComponentTestBase` automatically provides:
+- `test_latest_version` → Instantiates component via `component_class` and asserts `run()` doesn't return `None`.
+- `test_all_versions_have_a_file_name_defined` → Ensures mapping completeness vs `SUPPORTED_VERSIONS` constant (`src/backend/tests/constants.py`).
+- `test_component_versions` (parametrised) → Builds component from source for each supported version and asserts successful execution.
+
+When adding a new component test, **inherit from the correct base class and provide the three fixtures**. This greatly reduces boilerplate and enforces version compatibility.
+
+---
+
+## 3. Component Testing Requirements
+
+### Minimum Testing Requirements
+- **Unit Tests:** Create comprehensive unit tests for all new components
+- **Manual Test Documentation:** If unit tests are incomplete, create a Markdown file with manual testing steps
+  - Location: Same directory as unit tests
+  - Filename: Same as component but with `.md` extension
+  - Content: Detailed manual testing steps and expected outcomes
+
+### Testing Best Practices
+- Test both sync and async code paths
+- Mock external dependencies appropriately
+- Test error handling and edge cases
+- Validate input/output behavior
+- Test component initialization and configuration
+
+---
+
+## 4. Async Testing Patterns
+
+### Async Component Testing
+```python
+import pytest
+import asyncio
+
+@pytest.mark.asyncio
+async def test_async_component():
+    # Test async component methods
+    result = await component.async_method()
+    assert result is not None
+```
+
+### Testing Background Tasks
+```python
+@pytest.mark.asyncio
+async def test_background_task_completion():
+    # Ensure background tasks complete properly
+    task = asyncio.create_task(component.background_operation())
+    result = await asyncio.wait_for(task, timeout=5.0)
+    assert result.success
+```
+
+### Testing Queue Operations
+```python
+@pytest.mark.asyncio
+async def test_queue_operations():
+    # Test queue put/get operations without blocking
+    queue = asyncio.Queue()
+
+    # Non-blocking put
+    queue.put_nowait(test_data)
+
+    # Verify queue processing
+    result = await asyncio.wait_for(queue.get(), timeout=1.0)
+    assert result == test_data
+```
+
+---
+
+## 5. Special Testing Considerations
+
+### Blockbuster Plugin
+- Use `no_blockbuster` pytest marker to skip blockbuster plugin in tests
+- Example: `@pytest.mark.no_blockbuster`
+
+### Database Tests
+- `test_database.py` may fail in batch runs but pass individually
+- Run problematic tests sequentially: `uv run pytest src/backend/tests/unit/test_database.py`
+- Consider this behavior when writing database-related tests
+
+### Context Variables in Async Tests
+- Be aware of ContextVar propagation in async tests
+- Test both direct event loop execution and `asyncio.to_thread` scenarios
+- Ensure proper context isolation between test cases
+
+---
+
+## 6. Test Execution
+
+### Running Tests
+```bash
+make unit_tests        # Run all backend unit tests
+make integration_tests # Run integration tests (requires additional setup)
+make coverage         # Run tests with coverage (requires additional setup)
+make tests_frontend   # Run frontend tests (requires additional setup)
+```
+
+### Individual Test Execution
+```bash
+# Run specific test file
+uv run pytest src/backend/tests/unit/test_specific_component.py
+
+# Run specific test method
+uv run pytest src/backend/tests/unit/test_component.py::test_specific_method
+
+# Run with verbose output
+uv run pytest -v src/backend/tests/unit/
+```
+
+---
+
+## 7. Robust Testing Patterns
+
+### Error Handling Tests
+```python
+def test_component_error_handling():
+    """Test that component handles errors gracefully."""
+    with pytest.raises(ExpectedError):
+        component.method_that_should_fail(invalid_input)
+
+    # Test error message quality
+    try:
+        component.risky_operation()
+    except ComponentError as e:
+        assert "helpful error message" in str(e)
+```
+
+### Resource Cleanup Tests
+```python
+@pytest.fixture
+async def component_with_cleanup():
+    """Fixture ensuring proper resource cleanup."""
+    component = MyComponent()
+    await component.initialize()
+    try:
+        yield component
+    finally:
+        await component.cleanup()
+```
+
+### Timeout and Performance Tests
+```python
+@pytest.mark.asyncio
+async def test_operation_timeout():
+    """Test that operations respect timeout constraints."""
+    start_time = time.time()
+
+    with pytest.raises(asyncio.TimeoutError):
+        await asyncio.wait_for(
+            component.long_running_operation(),
+            timeout=1.0
+        )
+
+    elapsed = time.time() - start_time
+    assert elapsed < 1.5  # Allow some tolerance
+```
+
+---
+
+## 8. Documentation in Tests
+
+### Test Documentation Standards
+- Each test should have a clear docstring explaining its purpose
+- Complex test setups should be commented
+- Mock usage should be documented
+- Expected behaviors should be explicitly stated
+
+### Example Well-Documented Test
+```python
+async def test_component_background_processing():
+    """
+    Test that component processes items in background without blocking.
+
+    This test verifies:
+    1. Items are added to processing queue immediately
+    2. Background processing completes successfully
+    3. No deadlocks occur during shutdown
+    4. All tasks are properly cleaned up
+    """
+    # Setup component with background processing
+    component = BackgroundComponent()
+    await component.start()
+
+    try:
+        # Add items for processing
+        for i in range(10):
+            await component.add_item(f"item_{i}")
+
+        # Verify items are queued (non-blocking)
+        assert component.queue_size() == 10
+
+        # Wait for processing to complete
+        await component.wait_for_completion(timeout=5.0)
+
+        # Verify all items processed
+        assert component.processed_count() == 10
+
+    finally:
+        # Ensure clean shutdown
+        await component.stop()
+        assert component.is_stopped()
+```
+
+---
+
+## Testing Checklist
+- [ ] Unit tests created for all new components
+- [ ] Async patterns tested appropriately
+- [ ] Error handling and edge cases covered
+- [ ] Manual testing documentation created (if unit tests incomplete)
+- [ ] Background tasks and queues tested for proper cleanup
+- [ ] Database tests considered for sequential execution if needed
+- [ ] Appropriate pytest markers used (`no_blockbuster`, etc.)
+- [ ] Tests are well-documented with clear docstrings
+- [ ] Resource cleanup properly handled in fixtures
+- [ ] Timeout and performance constraints validated
+
+---
+
+## 9. Langflow-Specific Testing Patterns
+
+### Message Testing
+Test Langflow's `Message` objects and chat functionality:
+
+```python
+from langflow.schema.message import Message
+from langflow.utils.constants import MESSAGE_SENDER_AI, MESSAGE_SENDER_USER
+
+async def test_message_response(self, component_class, default_kwargs):
+    """Test Message object creation and properties."""
+    component = component_class(**default_kwargs)
+    message = await component.message_response()
+
+    assert isinstance(message, Message)
+    assert message.text == default_kwargs["input_value"]
+    assert message.sender == default_kwargs["sender"]
+    assert message.sender_name == default_kwargs["sender_name"]
+    assert message.session_id == default_kwargs["session_id"]
+    assert message.files == default_kwargs["files"]
+    # Test message properties structure
+    assert message.properties.model_dump() == {
+        "background_color": default_kwargs["background_color"],
+        "text_color": default_kwargs["text_color"],
+        "icon": default_kwargs["chat_icon"],
+        # ... other expected properties
+    }
+```
+
+### Flow Testing with JSON Data
+Use predefined JSON flows and utility functions:
+
+```python
+from tests.unit.build_utils import create_flow, build_flow, get_build_events, consume_and_assert_stream
+
+async def test_flow_execution(client, json_memory_chatbot_no_llm, logged_in_headers):
+    """Test flow creation, building, and execution."""
+    # Create flow from JSON data
+    flow_id = await create_flow(client, json_memory_chatbot_no_llm, logged_in_headers)
+
+    # Start the build process
+    build_response = await build_flow(client, flow_id, logged_in_headers)
+    job_id = build_response["job_id"]
+
+    # Get and validate event stream
+    events_response = await get_build_events(client, job_id, logged_in_headers)
+    assert events_response.status_code == codes.OK
+
+    # Process events and validate structure
+    await consume_and_assert_stream(events_response, job_id)
+```
+
+### Component Testing with Real Services
+Test components that need external APIs with proper markers:
+
+```python
+@pytest.mark.api_key_required
+@pytest.mark.no_blockbuster
+async def test_component_with_external_api(self):
+    """Test component with external API integration."""
+    api_key = os.getenv("OPENAI_API_KEY")
+
+    component = MyAPIComponent(
+        api_key=api_key,
+        model_name="gpt-4o",
+        input_value="test input",
+        session_id=str(uuid4()),
+    )
+
+    response = await component.message_response()
+    assert response.data.get("text") is not None
+```
+
+### Mocking Language Models
+Use `MockLanguageModel` for testing without external APIs:
+
+```python
+from tests.unit.mock_language_model import MockLanguageModel
+
+@pytest.fixture
+def default_kwargs(self):
+    return {
+        "agent_llm": MockLanguageModel(),
+        "input_value": "test message",
+        "session_id": str(uuid4()),
+        # ... other component-specific kwargs
+    }
+```
+
+### File Handling in Tests
+Use `anyio` and `aiofiles` for async file operations:
+
+```python
+import aiofiles
+import anyio
+
+async def test_file_operations(self, component_class, tmp_path):
+    """Test component file handling."""
+    # Create temporary test file
+    test_file = anyio.Path(tmp_path) / "test.txt"
+    await test_file.write_text("Test content", encoding="utf-8")
+
+    # Test with file input
+    component = component_class(files=[str(test_file)])
+    result = await component.run()
+
+    # Verify file was processed
+    assert len(result.files) == 1
+    assert await test_file.exists()
+```
+
+### API Endpoint Testing
+Test Langflow's REST API endpoints:
+
+```python
+async def test_flows_endpoint(client, logged_in_headers):
+    """Test flow creation via API."""
+    flow_data = {
+        "name": "Test Flow",
+        "description": "Test description",
+        "data": {"nodes": [], "edges": []}
+    }
+
+    response = await client.post(
+        "api/v1/flows/",
+        json=flow_data,
+        headers=logged_in_headers
+    )
+    assert response.status_code == codes.CREATED
+
+    flow = response.json()
+    assert flow["name"] == "Test Flow"
+    assert "id" in flow
+```
+
+### Build Config Testing
+Test component configuration updates:
+
+```python
+async def test_build_config_updates(self, component_class, default_kwargs):
+    """Test dynamic build configuration updates."""
+    component = await self.component_setup(component_class, default_kwargs)
+    frontend_node = component.to_frontend_node()
+    build_config = frontend_node["data"]["node"]["template"]
+
+    # Test configuration update
+    component.set(llm_provider="OpenAI")
+    updated_config = await component.update_build_config(
+        build_config, "OpenAI", "llm_provider"
+    )
+
+    assert updated_config["llm_provider"]["value"] == "OpenAI"
+    assert "gpt-4o" in updated_config["model_name"]["options"]
+```
+
+### Testing Event Streams
+Test real-time event streaming endpoints:
+
+```python
+async def consume_and_validate_events(response, expected_job_id):
+    """Consume NDJSON event stream and validate structure."""
+    count = 0
+    first_event_seen = False
+    end_event_seen = False
+
+    async for line in response.aiter_lines():
+        if not line:
+            continue
+
+        parsed = json.loads(line)
+
+        # Validate job_id in events
+        if "job_id" in parsed:
+            assert parsed["job_id"] == expected_job_id
+
+        # First event should be vertices_sorted
+        if not first_event_seen:
+            assert parsed["event"] == "vertices_sorted"
+            first_event_seen = True
+
+        # Track end event
+        elif parsed["event"] == "end":
+            end_event_seen = True
+
+        count += 1
+
+    assert first_event_seen and end_event_seen
+    return count
+```
+
+### Testing Component Versioning
+Test backward compatibility across Langflow versions:
+
+```python
+@pytest.fixture
+def file_names_mapping(self):
+    """Map component files across Langflow versions."""
+    return [
+        VersionComponentMapping(
+            version="1.1.1",
+            module="inputs",
+            file_name="chat"
+        ),
+        VersionComponentMapping(
+            version="1.1.0",
+            module="inputs",
+            file_name="chat"
+        ),
+        VersionComponentMapping(
+            version="1.0.19",
+            module="inputs",
+            file_name="ChatInput"
+        ),
+    ]
+```
+
+### Webhook Testing
+Test webhook endpoints with proper payload handling:
+
+```python
+async def test_webhook_endpoint(client, added_webhook_test):
+    """Test webhook flow execution."""
+    endpoint_name = added_webhook_test["endpoint_name"]
+    endpoint = f"api/v1/webhook/{endpoint_name}"
+
+    payload = {"path": "/tmp/test_file.txt"}
+
+    response = await client.post(endpoint, json=payload)
+    assert response.status_code == 202
+
+    # Verify webhook processed the payload
+    # ... additional validation logic
+```
+
+### Monkeypatch for Testing Errors
+Test error handling by mocking internal functions:
+
+```python
+async def test_cancellation_error(client, flow_id, logged_in_headers, monkeypatch):
+    """Test error handling during flow cancellation."""
+    import langflow.api.v1.chat
+
+    async def mock_cancel_with_error(*args, **kwargs):
+        raise RuntimeError("Cancellation failed")
+
+    monkeypatch.setattr(
+        langflow.api.v1.chat,
+        "cancel_flow_build",
+        mock_cancel_with_error
+    )
+
+    response = await client.post(
+        f"api/v1/build/{job_id}/cancel",
+        headers=logged_in_headers
+    )
+    assert response.status_code == codes.INTERNAL_SERVER_ERROR
+    assert "Cancellation failed" in response.json()["detail"]
+```
+
+