Accretion

AI agent harness that turns one sentence into a full-stack app: it plans with you, then builds the screens, server, and database.

Completed Nov 6, 2025

About this project

A FastAPI tool-calling build loop runs across 10 LLMs (OpenAI, Anthropic, Gemini) with context compaction and prompt caching, and builds inside E2B sandboxes with metered leases and per-user spend budgets. Every change is checked in a real browser on desktop and phone. MCP connectors (OAuth, per-tool approval) and bundled skills extend each build. The Next.js frontend provides plan review, chat, file viewer, live preview, and downloads.

Key features

• Plan mode: approve a plan before any code is written
• E2B sandboxed execution with lifecycle management and validation
• Real-time build streaming over resumable SSE
• Chat-driven iterative development with token-based rate limits

Technologies