Cool project, though - don't mean to take away anything from it.
I find the totally self-contained nature of them very appealing because it travels well through space and time, and it's incredibly accessible, both online and offline.
My current side project is actually using a WebDAV server to host a wide variety of different single HTML file apps that you can carry around on a USB drive or host on the web. The main trick to these apps is the same trick that TiddlyWiki uses, which is to construct a file in such a way that it can create an updated copy of itself and save it back to the server.
I'm attracted to this approach because it's a way to use relatively modern technologies in a way that is independent from giant corporations that want to hoover up all my data, while also being easy to hack and modify to suit my needs on a day-to-day basis.
The two projects out in the wild that natively work with this approach are TiddlyWiki and FeatherWiki.
I see room for a lightweight version of a calendar, a world clock, and even a lightweight spreadsheet that could be useful. I also have an idea for something I call a link trap where you can rapidly just drop links in and then search and sort over them to quickly retrieve something you saw before that was interesting. Sort of like my bookmarks-outside-the-browser except more of a history-outside-the-browser.
Edit: I sketched out a basic version in JS + Python, it's fairly ok to use. The nice parts about this approach is the HTML files are viewable without any extra services, and the service that enables saving doesn't itself need configuration or to keep state.
The downside is even though you know the current directory due to window.location the API is written in the way it assumes you either want a default location like "desktop" or need the user to navigate to the directory before you can do operations on it (for security reasons) even from a local context. The user needs to select the directory once per fresh page load (if you've dynamically reloaded the current content then multiple saves need only prompt once so long as you save the handle).
Any additional info/pointers on this ?
Is there some way to accomplish this through GitHub? Like the single html file running on GitHub.io pages can commit the changes to its repo?
My primary saver is a Python script that I wrote called Notedeck, but I also sometimes use a Rust webdav server called dufs.
I haven't released either of my projects I'm working on that are the client files, otherwise I would have just linked them.
For the benefit of the Hacker News audience that are curious, let me take a stab here.
The general strategy is to include JavaScript in the HTML document that knows how to look at various nodes in the DOM and create a new version of the document that uses an updated set of data.
Some sections of the data can be pulled verbatim. So, for example, if you have one giant script at the bottom of the doc, you can give it an ID of perhaps S, and then use that ID to retrieve the outer HTML of that script tag and insert it into the clone.
Other areas of the DOM need to be templated. So for example, I insert a script that is of type JSON, and that contains all of the data for the application. This can be pulled and stringified when creating the clone.
For a minority of attributes like the title and document settings like whether or not you're in light or dark mode, you want to avoid a flash of unstyled content and so you actually templatize those elements so they are written into the cloned copy with the updated data directly inline.
There's no real magic to it, but it can be a little bit tedious. One really interesting gotcha is that the script tag is parsed with higher precedence than quote tags. And so I have to break up all script tags that appear in any string that I'm manipulating so that the parser does not close out the script I'm writing.
I have a very minimal app that uses this technique called Dextral. I'll be happy to host it on my site and link it here.
That's not to say one couldn't still do what you're describing via other headers, I'm just saying "<input name=username><input name=password>" won't get it done