Ramp's engineering team built their own coding agent 'Inspect' that works like an engineer -- equipped with full context and tools to verify its own work. Inspect runs in sandbox environments for speed and safety, and currently handles about 30% of all Ramp pull requests. This article shares the detailed technical specs so anyone can build their own powerful coding agent.

1. Inspect: An Agent That Works Like an Engineer

Launched in January 2026, Inspect goes beyond writing code -- it verifies its own work like a real Ramp engineer. For backend tasks, it runs tests, reviews telemetry, and queries feature flags. For frontend work, it visually verifies results and provides screenshots and live previews.

Every session runs in a Modal sandbox VM with the same environment as local engineering (Vite, Postgres, Temporal), connected to Sentry, Datadog, GitHub, and Slack. Sessions start fast and cost nearly nothing, enabling developers to run multiple versions simultaneously, work from mobile, or leave sessions overnight. Internal adoption has been explosive -- about 30% of all merged PRs are now written by Inspect.

2. Sandbox: The Agent's Workspace

The core challenge is spinning up complete development environments instantly. Using Modal, they build images every 30 minutes (clone repo, install dependencies, run initial builds), save snapshots, and start new sandboxes from snapshots. OpenCode serves as the agent engine, recommended for its server-first architecture, typed SDK, and transparent source code.

Speed optimization tips: pre-warm sandboxes while users type prompts; allow file reading before sync completes (but block writing); move as much setup as possible into the 30-minute image build phase.

3. API and Multiplayer

The team uses Cloudflare Durable Objects with per-session SQLite databases and real-time streaming via Cloudflare Agents SDK. Multiplayer support is considered mission-critical -- enabling training sessions, real-time QA, and instant code review fixes. GitHub authentication ensures PRs are opened under the user's name rather than a bot account.

4. Clients: Work From Anywhere

• Slack: Natural language interface with automatic repository classification using fast, cheap models
• Web: Desktop and mobile client with hosted VS Code instances, streaming desktop views, and organization-wide usage statistics tracking merged PRs
• Chrome Extension: Visual modification of React apps by selecting elements and chatting, using DOM trees instead of screenshots to save token costs, deployable via managed device policy

Conclusion

By building their own tooling, Ramp created a system far more powerful and tailored than off-the-shelf products. Development speed increased with no limits on concurrency. The guide is shared so others can paste the link into a coding agent and start building their own powerful colleague.