Horus
An open-source runtime inspection tool that captures execution evidence for developers and coding agents through MCP.
Developer tools · Runtime inspectionOverview
A personal developer tool for investigating application behavior beyond logs. It captures runtime traces and values so developers and coding agents can inspect what happened.
Scope
Capture SDKs support Python, JavaScript, TypeScript, browser code, and PHP. The tool includes execution comparisons, monitoring charts, call maps, and usage heatmaps. Coding agents can access the captured evidence through MCP.
Stack
Next.js, React, TypeScript, Python, FastAPI, SQLite, and MCP.
Engineering challenge
Capturing runtime behavior accurately without changing how the application runs. Concurrent executions across Python, JavaScript, TypeScript, and PHP required preserving call relationships and value snapshots while limiting memory use and sending captures outside the request path.
Involvement
I designed the runtime capture architecture for traces, values, failures, call relationships, and execution evidence across Python, JavaScript/TypeScript, and PHP. I built the product with Next.js, TypeScript, Python/FastAPI, and SQLite, and published beta SDKs to npm, PyPI, and Packagist.