Reported symptom: only the FIRST download button in a multi-button
row pops the browser save dialog. The second and third do nothing on
click. Affects every tool page that exposes (cleaned + audit + config)
downloads.
Root cause is ``st.download_button`` itself — when several render in
the same script pass, the click-to-bytes wiring on the browser side
mis-routes and only one button's data is actually exposed. Explicit
``key`` arguments don't fix it; ``use_container_width=True`` doesn't
help either; we confirmed this in the Text Cleaner reverts.
Replace the widget with a real ``<a download="file" href="data:...">``
anchor rendered via ``st.markdown(..., unsafe_allow_html=True)``.
Bypasses Streamlit's widget machinery entirely; behaves identically to
a native browser download. Side benefit: clicking it does NOT trigger
a script rerun, so other in-flight UI state survives.
New helper ``html_download_button`` lives in
``src/gui/components/_legacy.py`` (exported from ``components``). API:
html_download_button(
label, data,
*, file_name, mime="application/octet-stream",
disabled=False, help=None, use_container_width=True,
)
Translation pattern applied across every tool page (and shared
``results_summary`` / ``config_panel`` widgets in ``_legacy.py``):
- ``st.download_button(`` -> ``html_download_button(``
- ``data=foo_bytes`` kwarg -> positional second arg
- ``key="..."`` -> dropped (helper has no widget identity)
- ``use_container_width=True`` -> dropped (default)
- ``disabled=`` and ``help=`` pass through unchanged
- Pre-computed byte buffers kept where they were
Total: 17 sites replaced (3 in Text Cleaner, 3 in Format
Standardizer, 3 in Fix Missing Values, 3 in Map Columns, 3 in
Automated Workflows, 2 in Find Duplicates page + 4 in shared
_legacy.py widgets used by Find Duplicates).
Caveat: data: URLs balloon by 33% (base64). Fine for tool output
sizes we ship; if a future result topped a few hundred MB we'd want a
Blob-URL fallback.
The marketing demo at src/gui/app_demo.py keeps its single
st.download_button — single button, no collision, no need to switch.
2008 tests pass.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
Michael
aeead05e4c