Asking ClaudeCode to decode Suunto Guide files

[matram]

Being a bit frustrated with not being able to upload FIT files without partner access to the API I downloaded a “.gui” file from the watch, originally uploaded by intervals.icu.

Here is Claudes take on the file, enjoy

Next step will be to see if I can extract this information to my own app on the watch.

Claude:
Interesting — this is a Suunto workout guide called “Aerobic Threshold 50” from Intervals.icu. Let me read the step files.

The picture is now clear. This is a Suunto workout guide exported from Intervals.icu — a 50-minute aerobic threshold run at 135–145 bpm. A few interesting things:

HR is stored in Hz, not bpm — step1.js shows:

• value: 2.333... Hz = 140 bpm
• low: 2.25 Hz = 135 bpm
• high: 2.4166... Hz = 145 bpm

That’s exactly why main.js has 60 * input.HeartRate — converting from Hz to bpm before doing anything with it.

step2.js is in Swedish — “SuuntoPlus-guiden avslutades” = “The SuuntoPlus guide ended”. Makes sense for your locale.

The file structure:

File	Purpose
manifest.jsn	Workout metadata, sensor subscriptions
main.js	Runtime engine (what we were formatting)
step0.js	Intro screen (50:00, 135–145bpm)
step1.js	Main interval — 50 min HR target step
step2.js	End screen
icon.pxb	Watch face icon (300×300, proprietary format)

So the main.js you were cleaning up is Suunto’s guide runtime — it dynamically loads each step{n}.js via evalFile() as the workout progresses.

[Dimitrios Kanellopoulos]

You can use Quantified Self for uploading Fit files