CSS styling breaks during hot reload (incremental builds)

[ichoosetoaccept]

Description

CSS styling intermittently stops loading during hot reload in the dev server. The page renders without any styling (raw HTML structure visible). Restarting bengal serve fixes the issue.

Repro steps

1. Start dev server: uv run bengal serve
2. Make changes to content files (e.g., edit markdown)
3. After an incremental rebuild, CSS stops loading
4. Browser shows unstyled page (no CSS applied)
5. Kill and restart bengal serve - styling works again

Expected

CSS should remain loaded and functional throughout all incremental rebuilds.

Actual

After some incremental rebuilds, CSS stops being served/loaded. The page renders but without any styling.

Environment

• Bengal version: 0.1.8
• Python version: 3.14
• OS: macOS

Investigation notes

Looked at the codebase and found potential causes:

1. Asset discovery skip logic (bengal/orchestration/content.py:580-599): During incremental builds when only content files change, asset discovery is skipped and cached asset data is used. This might cause CSS bundling to not be re-triggered.

2. Output asset detection thresholds (bengal/orchestration/build/provenance_filter.py:235-249): The check len(list(output_assets_dir.iterdir())) < 3 may be too low to detect when CSS needs rebuilding.

3. Theme asset check (bengal/orchestration/build/rendering.py:268-281): Uses arbitrary threshold < 5 files to determine if theme assets need processing.

Workaround

Restart bengal serve when styling breaks.

[lbliii]

I merged some updates related to this in, but will try to hammer my local site for a few days to see what happens. I've had a hard time nailing hot reload haha. Appreciate the tips.

Also, thank you for taking the time to try and look into Bengal. I believe you are the first person to do so.

[ichoosetoaccept]

You're welcome! I find bengal a fascinating project and have been investing time into improving it over at my fork: https://github.com/detailobsessed/bengal

I changed so much in the last two days that I can't easily create a PR back to your original project. Feel free to check it out, of course!

Perhaps we'll find a way to merge everything back to your project in the future. Right now I'm working on fixing failing tests and improving tests in general so I can hack on it further and improve without fear.

I want to use bengal for two real projects but as I started using it on the first, I kept running into little problems (styling inconsistencies, hot reload...) so I started hacking around in it. Then I couldn't stop 😂.

Cheers and thanks for creating bengal!

[lbliii]

That's awesome. I'm very open to changes! I've been a technical writer for 8 years, but never really shipped a code project. I'm trying to learn how to do it better. This has been very much a vibe coded adventure.

I'll take a look at your fork!