> On POSIX systems, in theory, we can just update the files in place. Except for dynamically loaded assets, this should work just fine. The OS treats file locking as advisory and open file descriptors are irrelevant, so even if the file is running you overwrite it in place and the user will get the freshest version on the next launch.

If you do this on macOS, and your code is codesigned, you are setting yourself for pain. Instead you should replace the file entirely so the file gets a new vnode.

If you want to do this really well I'd do it like A/B updates on Android work.

1. Have two directories for the app: A and B. One contains the "current" version and one contains (possibly) the "next" version.

2. Have the actual app you start be a separate launcher program that just picks which version to launch.

3. While the app is running, periodically check for updates. If an update is available download and unzip it to the A or B directory that isn't currently in use.

4. Next time the launcher program starts it can say "an updated version is already installed, would you like to use it" (or you can just do that automatically if you - or your user - decide that's the best option). If so it marks the appropriate A/B directory as "current" and launches that one.

Zero delay for users, works on all OSes, works with "always use the latest version" as well as "ask the user to update".

I've never tried this tbf - just an idea.

For Windows, there is an alternative approach: simply rename the running application to a different name (e.g. app.exe to app-old-timestamp.exe). This frees up the file name which can be overwritten to any other executable. The only problem I'm aware of is that this process may leave app.exe non-existent for a moment [1], but in return a need for keeping two executables vanishes.

[1] Technically speaking I believe this can be solved with transactional NTFS (deprecated but still available as of Windows 11, AFAIK).

Love that they prioritized both privacy (no sketchy background daemons) and security (launch-time checks) for legal apps—finally a team that gets how critical "no surprises" is for tools handling sensitive docs.

> An integrated drafting environment needs to be trusted with reading, editing and redlining confidential and trade secret documents.

And yet it's running on windows?!

At least on linux programs shouldn't update themselves. This is the package manager's job.

I use the `self_replace` crate for this: https://docs.rs/self-replace/latest/self_replace/