Add recho.state(value)

[pearmini]

Ref. #190

Here is a basic example for recho.state(value):

const [a, setA] = recho.state(0);

setTimeout(() => {
  setA((a) => a + 1);
}, 1000);

echo(a);

This feature is useful for interactive data structure visualization.

class Stack {
  pop() {}
  clone() {}
}

const [stack, setStack] = recho.state(new Stack());

echo(stack.values.join(",")):

recho.button("pop", () => {
  stack.pop();
  setStack(stack.clone());
});

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Deploying recho with    Cloudflare Pages

Latest commit:	dcd1c0b
Status:	✅  Deploy successful!
Preview URL:	https://fb16d009.recho.pages.dev
Branch Preview URL:	https://mutable.recho.pages.dev

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Project	Deployment	Preview	Comments	Updated (UTC)
recho-notebook	Ready	Preview	Comment	Nov 8, 2025 9:19pm

[Copilot]

Pull Request Overview

This PR adds a new state function to the standard library that provides React-like state management capabilities. The implementation is derived from Observable Notebook Kit's mutable and observe utilities.

• Implements a state() function that returns a tuple of [state, setState, getState] for reactive state management
• Adds the observe generator utility to support reactive value updates
• Includes test coverage for the new functionality

Reviewed Changes

Copilot reviewed 6 out of 6 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
runtime/stdlib/state.js	Implements the state() function and internal Mutable helper using the observe generator
runtime/stdlib/observe.js	Adds async generator for reactive value observation with initialization and disposal lifecycle
runtime/stdlib/index.js	Exports the new state function from the stdlib module
test/stdlib.spec.js	Adds test assertion to verify state is exported from stdlib
test/js/mutable.js	Adds test case demonstrating state usage with setter callbacks
test/js/index.js	Exports the new mutable test case

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