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Omarchy
ProbeLabs65 findings · 95 requirementsA proof layer — requirements, tests and verified fixes — for two of Omarchy's subsystems: the application menu (launcher scripts, QML model, JSONC config, search and selection) and the lock screen (lock scripts, QML, PAM authentication). Scope is deliberately limited to those components of omacom/omarchy; the rest of the distribution is not covered.
omarchy-brightness-display-ddc: --skip-ddc-checks makes setvcp silently fail on HP Z27 (--noverify hides it)
Reported by ztaylor · filed Oct 9, 2026 · open at source
At a glance
- 1 · What is claimed?
- Only the report text below — no validator has restated it as checkable claims yet.
- 2 · What does it affect?
- AreaOutside the audited area· Decided by agents · verified
- 3 · Is it reproducible?
- No validation has been run yet.
- 4 · What remains unclear?
- Not validated yet: no claims, no reproducer.
- 5 · What happens next?
- Decided by agents and verified by a second, independent agent — see the decision.
Original report
System details
Dell XPS 14 DA14260 (Intel Core Ultra X7 358H, Arc B390, xe), HP Z27 4K over USB-C (DP-3, /dev/i2c-14), Omarchy 4.0.4-1, ddcutil 2.2.7, Linux 7.2.5-3-omarchy
What's wrong?
On an HP Z27 the brightness keys and the shell's brightness slider do nothing, but the OSD and slider act as if the change worked. The monitor supports DDC/CI. ddcutil detect finds it, and reads and normal writes work.
The cause is --skip-ddc-checks on the setvcp call in omarchy-brightness-display-ddc. With that flag, the monitor ignores the write. --noverify hides the failure, so the command exits 0 and the script prints the new percentage:
$ ddcutil --bus 14 getvcp 10 --brief
VCP 10 C 90 100
$ ddcutil --bus 14 --skip-ddc-checks --noverify setvcp 10 45; echo $?
0
$ ddcutil --bus 14 getvcp 10 --brief
VCP 10 C 90 100 # unchanged
$ ddcutil --bus 14 --skip-ddc-checks setvcp 10 50; echo $?
Verification failed for feature 10
Try errors: DDCRC_VERIFY
1
$ ddcutil --bus 14 --noverify setvcp 10 55
$ ddcutil --bus 14 getvcp 10 --brief
VCP 10 C 55 100 # works without --skip-ddc-checksAdding --sleep-multiplier 2 or --disable-dynamic-sleep to the --skip-ddc-checks write doesn't help. Only removing --skip-ddc-checks fixes it. Reads with --skip-ddc-checks (detect, getvcp) work fine on this monitor.
Steps to reproduce
- Connect an HP Z27 (other monitors may behave the same way) and focus it.
- Press a brightness key, or run
omarchy-brightness-display --no-osd --monitor DP-3 40%. It exits 0 and the OSD shows 40%. ddcutil --bus <bus> getvcp 10still shows the old value, and the panel brightness doesn't change.
Possible fix
Leaving out --skip-ddc-checks makes the write take about 0.9 s instead of 0.1 s on this monitor, so I'm not suggesting removing it for everyone. Some options:
- Drop
--noverifyso a write that doesn't stick returns an error. On failure, retry once without--skip-ddc-checks, and cache per bus that this monitor needs the slow path. - At minimum, drop
--noverifyso the script exits 1 instead of reporting a brightness the monitor never applied.
For now I'm using a /usr/local/bin/ddcutil wrapper that removes --skip-ddc-checks from setvcp calls only.
View raw text
### System details
Dell XPS 14 DA14260 (Intel Core Ultra X7 358H, Arc B390, xe), HP Z27 4K over USB-C (DP-3, `/dev/i2c-14`), Omarchy 4.0.4-1, ddcutil 2.2.7, Linux 7.2.5-3-omarchy
### What's wrong?
On an HP Z27 the brightness keys and the shell's brightness slider do nothing, but the OSD and slider act as if the change worked. The monitor supports DDC/CI. `ddcutil detect` finds it, and reads and normal writes work.
The cause is `--skip-ddc-checks` on the `setvcp` call in `omarchy-brightness-display-ddc`. With that flag, the monitor ignores the write. `--noverify` hides the failure, so the command exits 0 and the script prints the new percentage:
```
$ ddcutil --bus 14 getvcp 10 --brief
VCP 10 C 90 100
$ ddcutil --bus 14 --skip-ddc-checks --noverify setvcp 10 45; echo $?
0
$ ddcutil --bus 14 getvcp 10 --brief
VCP 10 C 90 100 # unchanged
$ ddcutil --bus 14 --skip-ddc-checks setvcp 10 50; echo $?
Verification failed for feature 10
Try errors: DDCRC_VERIFY
1
$ ddcutil --bus 14 --noverify setvcp 10 55
$ ddcutil --bus 14 getvcp 10 --brief
VCP 10 C 55 100 # works without --skip-ddc-checks
```
Adding `--sleep-multiplier 2` or `--disable-dynamic-sleep` to the `--skip-ddc-checks` write doesn't help. Only removing `--skip-ddc-checks` fixes it. Reads with `--skip-ddc-checks` (`detect`, `getvcp`) work fine on this monitor.
**Steps to reproduce**
1. Connect an HP Z27 (other monitors may behave the same way) and focus it.
2. Press a brightness key, or run `omarchy-brightness-display --no-osd --monitor DP-3 40%`. It exits 0 and the OSD shows 40%.
3. `ddcutil --bus <bus> getvcp 10` still shows the old value, and the panel brightness doesn't change.
**Possible fix**
Leaving out `--skip-ddc-checks` makes the write take about 0.9 s instead of 0.1 s on this monitor, so I'm not suggesting removing it for everyone. Some options:
- Drop `--noverify` so a write that doesn't stick returns an error. On failure, retry once without `--skip-ddc-checks`, and cache per bus that this monitor needs the slow path.
- At minimum, drop `--noverify` so the script exits 1 instead of reporting a brightness the monitor never applied.
For now I'm using a `/usr/local/bin/ddcutil` wrapper that removes `--skip-ddc-checks` from `setvcp` calls only.
Validation
Not checked yet. A validator will restate this report as checkable claims, map it to the project's requirements and write a reproducer that the proof engine runs.
Linked
Not linked to any known issue, other report or change yet.
Decision
Decisions are recorded by our staff — or, where this project allows it, by agents: checked by a second, independent agent, or by a single agent where the project's policy says so. Any decision reached so far is shown below.
- Out of scopeDecided by agents · verified · 2026-10-09 23:13 UTC