Build your first Edron app¶

This path takes about five minutes with Python 3.11–3.14 and uv. Node.js is not required.

1.3 is published

Hedron 1.3.0 is available from PyPI. The documentation describes the stable Hedron 1.3 API contract.

1. Scaffold and run¶

uvx --from "edron>=1.0.0" edron new my-app --template minimal
cd my-app
uv sync
uv run edron run app:app --reload

Open http://127.0.0.1:8000. The generated project is an ordinary ASGI application and can also run with uv run uvicorn app:app --reload.

2. Understand the page¶

The generated app.py follows this shape:

import edron as ed

app = ed.App(title="Sales", security="standard")


@app.page("/", title="Sales dashboard")
class Home(ed.Page):
    def render(self) -> None:
        self.metric("Orders", 128, delta="+12")
        self.text("A useful page rendered entirely on the server.")

App owns the native application and registrations. A fresh Page instance handles each request. Calls such as metric() and text() append components to that request's page tree; the page instance is not durable user state.

Change 128 to 129, save the file, and refresh the browser.

3. Add a bounded interaction¶

Add these methods inside Home:

     @ed.fragment
     def status(self) -> None:
         self.text("All systems operational")

     @ed.action
     def refresh_status(self) -> ed.Outcome:
         return ed.refresh(self.status)

Then call them from render():

         self.status()
         self.button("Refresh status", action=self.refresh_status)

The button posts to a declared action. The outcome refreshes only the registered fragment, while Edron preserves Hedron's CSRF and target policies.

4. Verify the application¶

uv run edron check app.py
uv run edron explain app:app
uv run edron doctor app:app --profile local

check is static and does not execute the application. explain and doctor import only source you trust.

If something fails¶

Symptom	Fix
No matching Edron distribution	Confirm the version and index in Installation
`edron: command not found`	Use `uv run edron` or `python -m edron` in the project environment
Reload requires an import target	Use `app:app`, not a bare `.py` filename, with `--reload`
Port 8000 is busy	Add `--port 8001` and open that port
A POST returns 403	Load the page first, then review the security profile and CSRF guidance