Crash recovery is definitely something that I want to spend a bit more time on. I'm not entirely sure how Trace handles crashing right in the middle of a recording, so I'm going to put a bit of time aside in the next few days to properly explore this and see if I can come up with an elegant solution to it.

I think I've got the other two bits covered. I pushed an update yesterday that adds active echo cancellation so that audio playing through the speakers (or leaky headphones) won't get transcribed twice if it is picked up by the microphone. It can be disabled in preferences, but it's on by default.

The disk space issue is one that I considered as well. By default, Trace deletes the actual audio recordings as soon as transcription is successfully completed, so the idea is you keep just the markdown transcript rather than the gigabytes of raw audio. If you want, there's a preference to disable the auto-deletion. There's a bit more on the support page here https://traceapp.info/support (search for "Auto-deletion of audio").

FluidAudio is a big part of this and is actually used in two places during a session. It runs the Parakeet EOU model for the instant recap (which isn't hugely accurate, but it's good enough for the job) and after the call it's also used to transcribe the recording, depending on which engine you've selected (Trace offers a fast and an accurate one). If the fast engine is selected, we use FluidAudio with the Parakeet-TDT 0.6b v3 model for transcription, which then goes through Pyannote and WeSpeaker for diarization. If the accurate engine is selected, we use WhisperKit with the Whisper large-v3-turbo model for transcription, and SpeakerKit for diarization.

For crash resilient data, you have a few options:

- Journaling file structures (telegraph what you're about to write, then write it, then signal completion)

- memmap your important data structures to a file (they will be flushed to disk no matter how your app dies - short of a power loss)

- post-crash dump (put last-minute writers in a crash handler to save it to disk)

A journaling file structure is the most secure, because it's designed with the assumption that writing will eventually fail. memmapped structs are easy and cheap, and get you 99% of the way there (only power loss will lose your data). Crash-time writing is doable with a crash handler like KSCrash, but there are many ways an app can crash without triggering a crash handler (thermal kill, exceeding quota, memory jetsam, etc). You also need to write your data in a signal-safe manner.