Add README with usage instructions and example

Co-authored-by: Ona <no-reply@ona.com>

.devcontainer/Dockerfile

@@ -0,0 +1,10 @@
+FROM mcr.microsoft.com/devcontainers/base:ubuntu-24.04
+
+RUN apt-get update && export DEBIAN_FRONTEND=noninteractive \
+    && apt-get -y install --no-install-recommends \
+       curl unzip git ca-certificates \
+    && rm -rf /var/lib/apt/lists/*
+
+RUN curl -fsSL https://bun.sh/install | bash \
+    && ln -s /root/.bun/bin/bun /usr/local/bin/bun \
+    && ln -s /root/.bun/bin/bunx /usr/local/bin/bunx

.devcontainer/devcontainer.json

@@ -0,0 +1,8 @@
+{
+	"name": "jrx",
+	"build": {
+		"context": ".",
+		"dockerfile": "Dockerfile"
+	},
+	"postCreateCommand": "bun install && cd example && bun install"
+}

README.md

@@ -0,0 +1,159 @@
+# jrx
+
+JSX factory for [json-render](https://github.com/vercel-labs/json-render). Write JSX, get Spec JSON.
+
+## Install
+
+```bash
+bun add jrx @json-render/core
+```
+
+## Setup
+
+Configure your `tsconfig.json` to use jrx as the JSX source:
+
+```json
+{
+  "compilerOptions": {
+    "jsx": "react-jsx",
+    "jsxImportSource": "jrx"
+  }
+}
+```
+
+Or use a per-file pragma:
+
+```tsx
+/** @jsxImportSource jrx */
+```
+
+## Usage
+
+### Define components
+
+Create wrapper functions that map JSX tags to json-render component type names:
+
+```ts
+import { jsx } from "jrx/jsx-runtime";
+import type { JrxNode } from "jrx";
+
+export function Stack(props: Record<string, unknown>): JrxNode {
+  return jsx("Stack", props);
+}
+
+export function Text(props: Record<string, unknown>): JrxNode {
+  return jsx("Text", props);
+}
+
+export function Button(props: Record<string, unknown>): JrxNode {
+  return jsx("Button", props);
+}
+```
+
+### Render JSX to Spec JSON
+
+```tsx
+import { render } from "jrx";
+import { Stack, Text, Button } from "./components";
+
+const spec = render(
+  <Stack>
+    <Text content="Hello from jrx!" />
+    <Button label="Click me" />
+  </Stack>
+);
+```
+
+This produces:
+
+```json
+{
+  "root": "stack-1",
+  "elements": {
+    "text-1": {
+      "type": "Text",
+      "props": { "content": "Hello from jrx!" }
+    },
+    "button-1": {
+      "type": "Button",
+      "props": { "label": "Click me" }
+    },
+    "stack-1": {
+      "type": "Stack",
+      "props": {},
+      "children": ["text-1", "button-1"]
+    }
+  }
+}
+```
+
+### State, events, visibility, and watchers
+
+Pass json-render bindings as JSX props:
+
+```tsx
+const spec = render(
+  <Stack>
+    <Text content={{ $state: "/count" }} />
+    <Button
+      label="Increment"
+      on={{
+        press: {
+          action: "increment",
+          params: { statePath: "/count" },
+        },
+      }}
+    />
+    <Text
+      content="Hidden until toggled"
+      visible={{ $state: "/showDetails", eq: true }}
+    />
+  </Stack>,
+  {
+    state: {
+      count: 0,
+      showDetails: false,
+    },
+  }
+);
+```
+
+The `render()` function accepts an options object with `state` to include initial state in the Spec output.
+
+### Reserved props
+
+These props are extracted from JSX and mapped to Spec fields rather than passed through as component props:
+
+| Prop | Spec field | Description |
+|---|---|---|
+| `key` | element key | Explicit element key (overrides auto-generation) |
+| `visible` | `visible` | Visibility condition |
+| `on` | `on` | Event bindings |
+| `repeat` | `repeat` | Repeat configuration |
+| `watch` | `watch` | State watchers |
+| `children` | `children` | Child element references |
+
+## Example
+
+The `example/` directory contains a Bun HTTP server that demonstrates jrx in action. It shows JSX source, live rendered UI (via `@json-render/react`), and JSON output side by side.
+
+```bash
+cd example
+bun install
+bun dev
+```
+
+This starts a dev server with HMR at `http://localhost:3000`.
+
+## Development
+
+```bash
+bun install       # install dependencies
+bun run build     # build dist/
+bun test          # run tests
+bun run typecheck # type check
+```
+
+## License
+
+MIT