The JVM has bytecode and .NET has IL. Over the last couple of weeks Screenplay became that for the business: one .play model that people, AI assistants, Studio and your C# code all write, and that VS Code, your MCP host, your running Arc application and the Cratis CLI all draw as the same event model board.
Where an assistant meets Cratis: the AI corpus and its hooks, the CLI's effect labels, Chronicle MCP, Screenplay MCP and the docs assistant. What each one lets an assistant read, propose or change, and the checks that run whether it listened or not.
A shared board and canvas where people and AI agents work on the same event model, Screenplay text you can diff, and opt-in code for one slice in your own repository. What Cratis Studio does at each step, and where each step stops.
Prologue stands beside a running system, records the metadata of what it does, and proposes a Screenplay model for a person to correct. What it watches, what it never records, how it groups what it sees, and what a language model may and may not change.
Stage renders a narrow slice of a Screenplay model into C# on Arc and Chronicle, boots a throwaway sandbox and runs the model's examples, and refuses with a code whatever it can't express. Scene is the UI model between a screen in the model and React.
The .play language for writing an event model down next to the code, a compiler whose diagnostic codes don't change, personal data declared once on a value, and an MCP server that lets an assistant propose changes a person applies.
The sticky-note feature followed from its model to production, into year two and to agents writing its code, through every Cratis product this post names, with 26 more posts that take each one all the way down.
