The page asserted the Sceptre M34's EDID tops out at 180 Hz. Measured on blankpad
after the merge, `niri msg outputs` lists 3440x1440@239.998 — the claim was false
in main, and it was load-bearing: it is the reason nobody questioned the profile
while the panel ran at 60 Hz for weeks. The real defect was one character: the
profile asked for 239.999, the panel offers 239.998, and niri matches mode strings
verbatim, falling back to *preferred* without failing.
Corrected to the measured mode list, and the deployed 180 is now documented as a
deliberate choice (the link is trained at x8 32.0 GT/s against a max of x16 and the
display engine throws EINVAL), so the next reader neither "restores 240" blind nor
re-pins 180 as a hardware ceiling. The kdl profile comment carries the same facts at
the point of edit, because that is where the next change to this mode gets typed.
Refs #60
desk-1-home.kdl asked the Sceptre M34 for 3440x1440@239.999, a mode the panel
has never offered. niri does not reject an unavailable mode: it logs "configured
mode ... could not be found, falling back to preferred" and drives the EDID
preferred mode - 60 Hz - on every connector event, which is why the monitor
looked like it was dying rather than misconfigured. Read live with
`niri msg outputs`, the mode list tops out at 180.
Also destroys the copies of the phantom number: displays.md carried 239.999 in
its diagram, its panel table and its copy-paste pattern block, and its rule 4
claimed an impossible mode leaves the output dark. Rule 4 now states the real
failure mode, a new section separates config / DP-link / amdgpu-driver faults by
log signature, and wlr-randr is corrected to not-installed (three pages claimed
it; `pacman -Qs wlr` matches nothing).
Applied live with `niri msg output <panel> mode <mode>` - the temporary
per-output path, so no config reload and no logged-out session - verified at
3440x1440 @ 180.000 Hz with the compositor PID unchanged.
Refs #58
Frank