doubleagent

Test against real APIs without the real APIs.

High-fidelity fakes of third-party services for AI agent development. Run dozens of agents in parallel, iterate fast, and never worry about rate limits, state cleanup, or API costs.

Why?

AI agents iterate fast. Real APIs can't keep up:

• Rate limits. An agent debugging a task might hit the same endpoint 50 times in an hour. GitHub gives you 5,000 requests/hour. Run 10 agents? You're done in minutes.
• State collisions. Parallel agents create repos, post messages, fire webhooks - all stomping on each other's state with no isolation.
• No reset. Every run leaves garbage behind. You can't un-send a Slack message or un-create a GitHub repo without cleanup scripts.
• Cost. Stripe, Twilio, Okta - every API call costs money. Multiply by dozens of agents and hundreds of iterations.
• Slow feedback. Real calls take 200-500ms. Agents need millisecond responses to iterate quickly.

DoubleAgent gives you fakes that behave like the real thing - isolated per agent, instantly resettable, unlimited requests.

Quick Start

# Install
curl -sSL https://raw.githubusercontent.com/islo-labs/doubleagent/main/install.sh | bash

# Start a service
doubleagent start github

# Your code hits localhost instead of the real API
# Official SDKs just work

Usage

CLI

doubleagent start github              # Start on default port
doubleagent start github --port 9000  # Custom port
doubleagent start github slack        # Multiple services

doubleagent status                    # Show running services
doubleagent stop                      # Stop all
doubleagent reset github              # Clear state
doubleagent seed github ./data.yaml   # Load fixtures

When a service starts, the CLI prints the environment variable to use:

$ doubleagent start github
✓ github running on http://localhost:8080 (PID: 12345)
  Export: DOUBLEAGENT_GITHUB_URL=http://localhost:8080

Using with Official SDKs

Point the official SDK at the fake service URL:

import os
from github import Github

# Use the env var set by doubleagent start
client = Github(
    base_url=os.environ["DOUBLEAGENT_GITHUB_URL"],
    login_or_token="fake-token"
)

repo = client.get_user().create_repo("test-repo")
issue = repo.create_issue(title="Test issue")

Project Configuration

Define which services your project needs in a doubleagent.yaml file at the root of your repository:

services:
  - github
  - slack

When this file exists, you can install all services at once:

# Reads doubleagent.yaml and installs all listed services
doubleagent add

Without the file, you specify services explicitly:

doubleagent add github slack

The CLI finds doubleagent.yaml (or doubleagent.yml) by searching from the current directory upward, so it works from any subdirectory in your project.

Example: full project setup

# doubleagent.yaml
services:
  - github
  - slack
  - stripe

# One command to install everything
doubleagent add

# Start the services you need
doubleagent start github slack

Fakes, Not Mocks

Mocks return hard-coded responses. Call create_customer() and get {"id": "cus_123"} every time.

Fakes implement real behavior. Create a customer, it gets stored. Retrieve it later, it's there. Delete it, it's gone.

• Contract-tested — Every fake passes tests against the real API
• Official SDK compatible — Use PyGithub, stripe-python, etc. directly
• Built by agents, for agents — Designed for AI agent workflows

Available Services

Service	Status	Official SDK
GitHub	✅ Available	PyGithub, octokit
Jira	🚧 Coming soon	atlassian-python-api
Slack	✅ Available	slack_sdk
Okta	🚧 Coming soon	okta
Auth0	🚧 Coming soon	auth0-python
Stripe	🚧 Coming soon	stripe

Contributing

1. Create services/<name>/
2. Implement the fake with /_doubleagent/health, reset, and seed endpoints
3. Write contract tests with the official SDK
4. Validate against the real API

See docs/contributing.md for details.

Required Service Interface

Every service must implement these endpoints:

Endpoint	Method	Purpose
/_doubleagent/health	GET	Health check
/_doubleagent/reset	POST	Clear all state
/_doubleagent/seed	POST	Seed state from JSON

License

MIT