Why `halo power`?

One-line answer: Strix Halo shares one LPDDR5 memory controller between CPU and GPU, so package-power spent on idle x86 cores directly costs decode tok/s. halo power exposes three named envelopes that you can flip between without memorizing ryzenadj flags.

The three profiles

Profile	stapm	fast	slow	tctl	When to switch to it
`inference`	65 W	80 W	75 W	95 °C	Long bitnet decode, batch PPL runs, burn-in sweeps.
`chat`	45 W	65 W	55 W	90 °C	Default — interactive `halo chat`, 1bit-helm traffic.
`idle`	20 W	35 W	25 W	80 °C	Closet-quiet after >60 s of zero traffic.

Values come from docs/halo-power-design.md; they're a starting point pending a decode-bench sweep.

Why these three and not more?

We drive profile by traffic pattern, not by per-process rules (the RyzenZPilot model). Our process set is small and our HTTP surface is one server — three envelopes cover every realistic 1bit systems workload and every extra knob is just another thing to forget about.

How it works under the hood

halo power <profile> → sudo ryzenadj --tctl-temp=N --slow-limit=N --fast-limit=N --stapm-limit=N.
Flag order is deliberate: thermal ceiling up first, power limits up second. Ctrl-C mid-apply leaves you in a safe state.
halo power (no args) reads back current state via ryzenadj --info.
halo power --dry-run inference prints the argv without executing.

Why not link a Rust ryzenadj crate?

Because FlyGoat/ryzenadj tracks AMD Family 19h stepping quirks upstream. When a new Strix Halo BIOS lands, we pacman -Syu and inherit the fix. A vendored Rust port would make us the second ryzenadj maintainer — an 800–1200-LOC commitment for ~zero upside. See docs/halo-power-design.md option (c).

Install

Not bundled. ryzenadj is an AUR/pacman package on CachyOS:

sudo pacman -S ryzenadj

If it's missing, halo power warns cleanly and no-ops — the CLI stays usable on boxes where thermal tuning isn't relevant (e.g. dev laptops).

Not in scope

CPU governor (cpupower), amdgpu sysfs (power_dpm_force_performance_level), and fan curves (BIOS/EC) are all owned elsewhere. See docs/halo-power-design.md safety notes.