V0.dev Response Capture Tool: API Capture & Testing Streamline

V0.dev Response Capture Tool

A tool that connects to your browser, navigates to v0.dev, submits prompts, and captures all network responses - including the streamed AI responses. This allows you to save the complete output from v0.dev for further analysis or use.

Features

• Connects to your existing Chrome browser with all your accounts/cookies
• Navigates to v0.dev and submits your prompt
• Captures all network activity, focusing on streamed AI responses
• Decodes the Vercel AI SDK streaming format to extract complete responses
• Saves responses to files for later reference
• Provides tools to extract and view responses from saved files

Prerequisites

• Python 3.8+
• Google Chrome browser

Installation

1. Clone this repository
2. Install dependencies:

# Using pip
pip install -r requirements.txt

# OR using uv
uv pip install -r requirements.txt

# Install Playwright browsers
python -m playwright install chromium

Usage

Capturing a v0.dev response

Run the script with a prompt to capture the response:

# Use the default prompt (calendar app)
python main.py

# Specify a custom prompt
python main.py monitor --prompt "Build a landing page for a coffee shop with a menu section and contact form"

The script will:

1. Connect to your Chrome browser (or launch a new instance)
2. Navigate to v0.dev
3. Submit your prompt
4. Capture all network activity, including the streaming responses
5. Save the responses to the captures directory

Listing captured files

List all the files in your captures directory:

python main.py list

Extracting responses from captured files

Extract and display the complete response from a captured file:

python main.py extract captures/full_response_1234567890.txt

This will:

1. Parse and decode the captured file
2. Extract the complete text response
3. Display it in the terminal
4. Save a clean version to a new file

How It Works

Vercel AI SDK Streaming Format

v0.dev uses the Vercel AI SDK to stream responses in a Server-Sent Events (SSE) format:

data: {"type":"data","value":[{"text":"Building"}]}
data: {"type":"data","value":[{"text":" a"}]}
data: {"type":"data","value":[{"text":" calendar"}]}
data: {"type":"message_annotations","value":[{"type":"finish_reason","message":"stop"}]}

Our tool:

1. Captures these streamed responses
2. Decodes the format to extract the text content
3. Assembles the complete response
4. Saves both raw and processed data

File Types

The tool saves several types of files:

• sse_stream_*.jsonl: Raw SSE stream data
• sse_decoded_*.jsonl: Decoded JSON events from the stream
• assembled_content_*.txt: Assembled text content from the stream
• full_response_*.txt: Complete, cleaned response text

Troubleshooting

If you have issues:

1. Try closing all Chrome instances and run the script - it will launch Chrome with your profile

2. For browser installation issues:

   python -m playwright install chromium

3. If responses aren't being captured properly, increase the monitoring time in tools.py

Advanced Usage

Directly using the extraction tool

You can also use the extraction function directly from the tools.py file:

python tools.py extract captures/your_captured_file.jsonl

Custom monitoring duration

By default, the script monitors for 60 seconds. For complex prompts that take longer, you can modify the monitor_v0_interactions function in tools.py to increase the monitoring time.