[szemyd]

The bug

A plain pip install aperiodic (the README's first instruction) installs no HTTP client. The first data call then falls to the Pyodide transport and crashes:

ModuleNotFoundError: No module named 'pyodide'
RuntimeWarning: coroutine 'get_symbols_async' was never awaited

This turned up while testing the 4.4.0 release. aperiodic.login() works on a plain install, since it only uses the standard library, so the very next call is where people hit it. The bug itself is older than #43.

The fix

• Clear error: outside Pyodide, the Pyodide transport is only ever chosen because httpx is missing. It now raises an ImportError that names the fix: pip install "aperiodic[polars]" or pip install "aperiodic[pandas]". This happens in run_async, fetch_json and download_parquet_bytes, and run_async closes the coroutine first, so there's no "never awaited" warning.
• Detection: _has_pyodide_ffi() returns False instead of raising when there's no pyodide package at all.
• README: installation now leads with pip install "aperiodic[polars]" # or "aperiodic[pandas]", and says a plain install is enough to sign in but not to fetch data.
• Pyodide unaffected: inside Pyodide, or in tests that fake it through sys.modules, nothing changes.

Checks

• New TestPlainInstall tests cover detection returning False, sync calls naming the extra and closing the coroutine, and async calls naming the extra. All three fail on main and pass here.
• A fresh venv with a plain install, calling get_symbols(...), now ends with the ImportError above instead of the pyodide crash.
• ruff 0.14.1 (CI's version) is clean.
• The full suite shows the same 34 integration failures as main (they need a real key and network); 199 pass.

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