Agent JSX

One authored definition ยท explicit runtime contracts

Write agents normally.
Compose the hierarchy once.

Agent files render one model-facing definition for models, prompts, input/output schemas, tools, skills, and MCP servers while owning state and callable methods. Composition JSX owns parent/child relationships and explicit authority. The model-driven Cloudflare target lowers the complete definition; deterministic reconcile and legacy Flue adapters keep their narrower existing contracts.

Read the API Chess example
agents/chess-match.agent.tsx
class ChessMatch extends Agent<ChessState> {
  static agentName = "chess-match";
  initialState = initialChessState;

  render() {
    return this.define({
      model: "openrouter/openai/gpt-5-mini",
      description: "Run a validated chess match."
    });
  }

  get turn() {
    return turnFor(this.state);
  }

  @callable()
  handleTurn(decision: ChessDecision) {
    this.setState(state =>
      reduceChessTurn(state, decision)
    );
  }
}
match.tsx
composeAgent(
  <ChessMatch name="match">
    {({ turn, handleTurn }) => turn && (
      <Board turn={turn}>
        <Player
          agentClass={OpenAIPlayer}
          turn={turn}
          onTurn={result(handleTurn)}
        />
      </Board>
    )}
  </ChessMatch>
);
Cloudflare model-driven boundary: Native agentTool returns child output to the parent model. It does not carry parent callbacks, methods, result(...) callables, or render-prop continuations into the child facet; the Think target emits a diagnostic for each dropped capability kind.

Core primitives

A small authored surface

Agent<S, P>Stateful, hierarchy-free agent definition. render() / define()One required, model-facing definition; never UI. state / setStateDurable state with ordinary update semantics. @callable()Explicit public method surface. promptPlain text or priority-aware prompt JSX. inputSchema / outputSchemaValidated native child-tool input and structured output. tools / skills / MCPCloudflare model capabilities declared beside the model. composeAgent()Hierarchy and authority live at the call site.

Compiler targets

Runtime glue is derived

TargetGenerated mapping
Cloudflare reconcileDurable classes, callable proxies, props, callback RPC, migrations, and deterministic infrastructure convergence.
Cloudflare model-drivenThe complete rendered definition: model, live prompt composition, schema boundaries, tools, skills, MCP clients, durable turns, and reasoning traces.
Legacy FlueThe existing low-level profile, roster, tool, and workflow adapter; no new full-definition support is implied.