Report: Anthropic's hidden 'Antspace' PaaS found in Claude Code
A researcher reverse-engineered Claude Code's Firecracker microVM: a full deploy pipeline, a Supabase-wired app builder, and the specs of the box your code runs on.
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A Vercel competitor, hidden in the runner
Reverse-engineering Claude Code's environment-runner (a 27MB unstripped Go binary from anthropic/api-go/environment-manager) reportedly surfaced Antspace, an unannounced Anthropic deploy platform. Its pipeline builds locally, uploads a single tar.gz artifact, and streams NDJSON status (packaging to building to deployed) through a bearer-token control plane. Anthropic looks to be quietly building where you ship, not just what writes your code.
The box your code actually runs on
The sandbox is a Firecracker microVM (the tech under AWS Lambda): 4 vCPU Cascade Lake at 2.8GHz, 16GB RAM, 252GB disk, Linux 6.18.5, restored from a frozen snapshot instead of cold-booted. A custom init, process_api, supervises processes over a WebSocket API (port 2024) and HTTP control API (port 2025). If you run code in Claude's sandbox, that is your ceiling.
Baku: prompt to database to deployed
Baku, the builder experience behind claude.ai, reportedly ships a Vite + React + TypeScript template, auto-provisions a Supabase database over MCP (SQL migrations and Edge Functions included), and defaults its deploy target to Antspace, not Vercel. It sketches a full vertical stack that squares up against Replit, Bolt, Vercel and Supabase at once.
The catch: it's staging, not a product
Nothing here is announced or public. The binary is an unstripped staging build (staging-68f0dff496), there is no external API, and it comes from one researcher's teardown of unreleased internals. Read Antspace as a signal of Anthropic's roadmap, not something you can deploy to this weekend.