What Flue Actually Innovates
- Virtual sandbox by default. First framework to invert the hierarchy: default to virtual (just-bash + AgentFS), opt into containers only when needed. 100x faster startup, zero idle cost, scales to millions of concurrent agents. Most frameworks assume Docker from the start.
- Durable Objects session persistence. On Cloudflare Workers, session state auto-persists via Durable Objects (SQLite per session). No external database, no manual serialization. Sessions survive across requests without code. Hibernates when idle.
- Sandbox tiering. Explicit levels: virtual (default, lightweight) → local (CI, host filesystem) → container (full Linux). Choose per agent based on needs. No other framework offers this hierarchy.
- Runtime-agnostic build. Same agent code deploys to Node.js, Cloudflare Workers, CLI via adapters. Not a technical innovation (Astro/Next.js do this), but applied to agents.
What's NOT novel: Schema validation (MCP reinvention), Markdown skills (industry pattern), Workers deployment (Cloudflare has cloudflare/agents), MCP integration (standard protocol).
Flue is a developer framework (build agents), not an agent platform (deploy agents). Compare to platforms: OpenClaw · ElizaOS · Muaddib · NemoClaw