DOOM MCP vs Stage

Chris Nager built a fully playable DOOM that runs as an MCP (Model Context Protocol) app, rendering inline inside Claude and ChatGPT without a separate browser tab. The architecture uses two MCP tools — create_doom_session for inline-capable hosts and get_doom_launch_url as a browser fallback — combined with cloudflare/doom-wasm for the game runtime and a signed token system that maintains session state across both surfaces. The result is the same session whether you're playing inline or in a tab. The key technical challenge was avoiding iframe and CSP (Content Security Policy) issues. Rather than embedding a browser page inside the MCP iframe, the DOOM canvas runs directly inside the host's iframe — a subtle but critical distinction that resolved a class of rendering and input-handling bugs. The final implementation is intentionally stripped down: no save/load, no persistence adapters, just stable playable DOOM. Beyond the novelty, this project is a concrete demonstration that MCP apps are interactive surfaces, not just tool-calling JSON endpoints. The progressive enhancement pattern — same signed-token foundation serving both inline and browser modes — is a reusable architecture for any game or interactive experience that wants to live inside an AI assistant. Nager open-sourced the implementation and the blog post is a detailed technical breakdown.

Stage is a code review tool built around a simple thesis: AI agents are writing more code than humans can meaningfully review, and the existing review UX (giant diffs, stale PR comments) was designed for human-paced development. Stage reimagines the review interface for the agentic era, surfacing risk signals, grouping semantically related changes, and inserting human checkpoints at high-stakes decision points rather than asking engineers to rubber-stamp thousands of AI-generated lines. The tool integrates with GitHub and works as a layer on top of existing CI/CD pipelines. It uses LLMs to classify code changes by risk level — security-sensitive, performance-critical, API contracts, etc. — and routes those changes to human reviewers while automatically approving lower-risk patches. The goal is to shrink the "important stuff humans should actually review" surface area to something manageable. Stage appeared on Hacker News Show HN with 114 points, suggesting strong resonance with engineers who are feeling the quality-control squeeze from AI coding tools. As Claude Code, Cursor, and similar tools push toward fully autonomous commits, Stage represents the counter-pressure: human oversight tooling that scales to agent-speed development.