Nunc: why I built my own fitness stack
2026 is, arguably, the year of AI. The first full year when one could really point it at a task, and see results. I’ve built three pieces with Claude Code this year:
Vestigator
Hacking Bluetooth Sports Tech for Fun and Profit — Part 9: Decoding the Record, Byte by Byte
Part 7 left the MG's sync buffer wide open and its contents shut: 109-byte per-second records and 73-byte raw-PPG bursts, with heart rate at one known offset
Hacking Bluetooth Sports Tech for Fun and Profit — Part 7: WHOOP 5 & MG — Same Handshake, New Data Format
The newer straps speak almost the same language as the WHOOP 4 we researched in Parts 4–6. Almost. The handshake byte changed, the framing grew, and the one command that would have
Hacking Bluetooth Sports Tech for Fun and Profit — Part 6: What's in Whoop's Overnight Buffer?
The WHOOP records all night and stores in in a buffer until requested. Here's what's actually in that buffer, the field map that I misunderstood, and the command that
Hacking Bluetooth Sports Tech for Fun and Profit — Part 5: How Accurate Is DIY HRV From a Hacked WHOOP?
Six nights, 356,000 records, thirteen algorithm variants, and a surprisingly honest answer from the data.
In the previous posts I documented the WHOOP's proprietary BLE protocol, built a passive daemon