Panel does not work with Pyodide

# Panel does not work with Pyodide

## My Experience

Panel + Pyodide often crashes or raises exception:

- Does not work with Pyodide 0.29.3
- Does not work with latest version of PyScript 
- v0.28.2 crashes less in Firefox than Chrome/ Edge
- v0.28.2 crashes less if I have the developer console open
- v0.28.2 crashes less if I send "Cross-Origin-Opener-Policy", "same-origin" and "Cross-Origin-Embedder-Policy", "credentialless" headers
- v0.28.2 crashes less on my laptop than served behind jupyterhub proxy

## Request

Please

- Please update the documentation https://panel.holoviz.org/how_to/wasm/standalone.html to latest versions of pyodide and pyscript
  - Please fix the pyodide version in the pyscript examples to ensure they will work in the future for users.
  - Test the examples across edge, chrome and firefox browsers. Fix any issues identified.

## Test Code

<details><summary>test_0293.html</summary>

```html
<!DOCTYPE html>
<html>
  <head>
    <script type="text/javascript" src="https://cdn.jsdelivr.net/pyodide/v0.29.3/full/pyodide.js"></script>
    <script type="text/javascript" src="https://cdn.bokeh.org/bokeh/release/bokeh-3.8.2.js"></script>
    <script type="text/javascript" src="https://cdn.bokeh.org/bokeh/release/bokeh-widgets-3.8.2.min.js"></script>
    <script type="text/javascript" src="https://cdn.bokeh.org/bokeh/release/bokeh-tables-3.8.2.min.js"></script>
    <script type="text/javascript" src="https://cdn.jsdelivr.net/npm/@holoviz/panel@1.8.7/dist/panel.min.js"></script>
  </head>
  <body>
    <div id="app"></div>
    <script type="text/javascript">
      async function main() {
        let pyodide = await loadPyodide();
        await pyodide.loadPackage("micropip");
        const micropip = pyodide.pyimport("micropip");
        await micropip.install([
          "https://cdn.holoviz.org/panel/1.8.7/dist/wheels/bokeh-3.8.2-py3-none-any.whl",
          "https://cdn.holoviz.org/panel/1.8.7/dist/wheels/panel-1.8.7-py3-none-any.whl"
        ]);
        pyodide.runPython(`
          import panel as pn
          pn.extension(sizing_mode="stretch_width")
          slider = pn.widgets.FloatSlider(start=0, end=10, name='Amplitude')
          def callback(new):
              return f'Amplitude is: {new}'
          pn.Column("Pyodide: 0.29.3", slider, pn.bind(callback, slider)).servable(target='app');
        `);
      }
      main();
    </script>
  </body>
</html>
```
</details>

<details><summary>test_0282.html</summary>

```html
<!DOCTYPE html>
<html>
  <head>
    <script type="text/javascript" src="https://cdn.jsdelivr.net/pyodide/v0.28.2/full/pyodide.js"></script>
    <script type="text/javascript" src="https://cdn.bokeh.org/bokeh/release/bokeh-3.8.2.js"></script>
    <script type="text/javascript" src="https://cdn.bokeh.org/bokeh/release/bokeh-widgets-3.8.2.min.js"></script>
    <script type="text/javascript" src="https://cdn.bokeh.org/bokeh/release/bokeh-tables-3.8.2.min.js"></script>
    <script type="text/javascript" src="https://cdn.jsdelivr.net/npm/@holoviz/panel@1.8.7/dist/panel.min.js"></script>
  </head>
  <body>
    <div id="app"></div>
    <script type="text/javascript">
      async function main() {
        let pyodide = await loadPyodide();
        await pyodide.loadPackage("micropip");
        const micropip = pyodide.pyimport("micropip");
        await micropip.install([
          "https://cdn.holoviz.org/panel/1.8.7/dist/wheels/bokeh-3.8.2-py3-none-any.whl",
          "https://cdn.holoviz.org/panel/1.8.7/dist/wheels/panel-1.8.7-py3-none-any.whl"
        ]);
        pyodide.runPython(`
          import panel as pn
          pn.extension(sizing_mode="stretch_width")
          slider = pn.widgets.FloatSlider(start=0, end=10, name='Amplitude')
          def callback(new):
              return f'Amplitude is: {new}'
          pn.Column("Pyodide: 0.28.2", slider, pn.bind(callback, slider)).servable(target='app');
        `);
      }
      main();
    </script>
  </body>
</html>
```

</details>

## Possible causes (LLM Research)

- **Pyodide v0.29.x upgraded to Python 3.13.2 and Emscripten 4.0.9** with an ABI break. Panel's pre-built wheels may be incompatible with the new ABI.
  - [Pyodide 0.28 Release Blog](https://blog.pyodide.org/posts/0.28-release/) — documents the Python 3.13 / Emscripten 4.0.9 upgrade and the new `pyodide_2025_0` ABI; lists 13 packages disabled due to ABI incompatibility
  - [Pyodide Platform ABI Documentation](https://pyodide.org/en/stable/development/abi.html) — explains the `pyodide_2025_0` ABI, wheel compatibility rules, and the `-fwasm-exceptions` requirement
  - [PEP 783 – Emscripten/WASI Packaging](https://peps.python.org/pep-0783/) — defines the `pyodide_${YEAR}_${PATCH}_wasm32` platform tag format and "one ABI per Python version" strategy
  - [Pyodide Loading Packages Documentation](https://pyodide.org/en/stable/usage/loading-packages.html) — explains that wheels must match the Pyodide ABI; micropip can only load compatible wheels
  - [Polars PR #24058](https://github.com/pola-rs/polars/pull/24058) — real-world example of rebuilding wheels for the `pyodide_2025_0` ABI

- **JSPI (JavaScript Promise Integration)** became enabled by default in Chrome 137+ and Pyodide v0.28+ uses it. v0.29.x may have changed JSPI behavior that interacts poorly with Bokeh/Panel's async rendering.
  - [V8 Blog: Introducing the WebAssembly JSPI API](https://v8.dev/blog/jspi) — primary technical introduction to JSPI from the V8 team
  - [V8 Blog: WebAssembly JSPI has a new API](https://v8.dev/blog/jspi-newapi) — documents the API changes available in Chrome M126+
  - [JSPI in Pyodide (Pyodide Blog)](https://blog.pyodide.org/posts/jspi/) — explains how JSPI enables `asyncio.run()` and `loop.run_until_complete()` in Pyodide
  - [Pyodide Issue #5702](https://github.com/pyodide/pyodide/issues/5702) — STATUS_STACK_BUFFER_OVERRUN crashes with JSPI enabled on Chrome; crashes do not occur with JSPI disabled
  - [Bokeh Issue #12118](https://github.com/bokeh/bokeh/issues/12118) — documents that getting Bokeh to render in Pyodide with bidirectional JS sync is non-trivial
  - [WebAssembly/js-promise-integration spec](https://github.com/WebAssembly/js-promise-integration) — official W3C WebAssembly CG specification repository

- **WebAssembly exception handling** was changed in v0.29.x (switched to native Wasm exceptions for C++ errors and setjmp/longjmp), which could affect how Pyodide handles errors during wheel installation.
  - [Pyodide v0.29 Changelog](https://pyodide.org/en/stable/project/changelog.html) — documents the switch to native Wasm exception handling for C++ errors, Rust panics, and setjmp/longjmp (marked as ABI break)
  - [Emscripten: C++ Exception Support](https://emscripten.org/docs/porting/exceptions.html) — explains `-fwasm-exceptions` vs the older JS-based `-fexceptions` approach
  - [Emscripten: setjmp/longjmp Support](https://emscripten.org/docs/porting/setjmp-longjmp.html) — documents `-sSUPPORT_LONGJMP=wasm` vs the JS-based implementation
  - [Emscripten Issue #20165](https://github.com/emscripten-core/emscripten/issues/20165) — compatibility issues when mixing `-fexceptions` with `-fwasm-exceptions`

## Reproduce

I will add examples in separate posts below.

I and Claude maintain a list of not yet reported issues here https://github.com/panel-extensions/panel-live/blob/main/dev/issues/standalone-wasm-examples-broken.md. I plan to manually reproduce before posting here.

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Panel does not work with Pyodide #8416

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Panel does not work with Pyodide #8416

Description

Panel does not work with Pyodide

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Reproduce

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