docs(niri): own the portable desk and the no-match defect

displays.md still described desk-2-portable as an EDID-pending skeleton
and left the PM1601 identity unnamed. record the second desk's rig,
its position math, and the law that a rig with no eligible profile runs
the previous desk's values rather than "unchanged" — the failure that
left the portable panels on 3440x1440@180 fallbacks for weeks.

omp-docs/tools/niri/displays.md

@@ -8,7 +8,7 @@ tags:
   - monitors
   - rotation
   - desk-profiles
-verified: 2026-10-21
+verified: 2026-10-30
 ---
 
 # Display Configuration
@@ -49,7 +49,7 @@ the dock and the cable, which is why the config keys on the EDID long name inste
 | Panel | EDID long name | Keyed by | Notes |
 |-------|----------------|----------|-------|
 | Sceptre M34 ultrawide | `Sceptre Tech Inc Sceptre M34 Unknown` | identity | `mode "3440x1440@180.000"`, **deliberate** — the panel also offers `3440x1440@239.998`, `144.001` and `120.000`; 180 is driven while the link is degraded (see the law below) — `focus-at-startup` |
-| PM1601 portrait | *not captured* | connector `HDMI-A-1` | dock-dependent; run `desk.sh capture` when plugged in, then re-key |
+| PM1601 portrait | captured 2026-10-30 — the two panels are `PNP(XYM) PM1601 0000000000000` and `PNP(XYM) PM1601 demoset-1` | connector `HDMI-A-1` in *this* profile; identity on the portable desk | dock-dependent; the identity key is known now, so re-key the block when the panel next rotates through a dock |
 | eDP-1 laptop panel | `Lenovo Group Limited 0x40A9 Unknown` | identity | scale **1.0** (deliberate; Ghostty grid at 1.25 rejected 2026-10-09), second `focus-at-startup` |
 
 VRR: the M34 supports it (its connector today is `DP-1`); **left disabled by
@@ -58,6 +58,40 @@ decision** (2026-10-09). Add `variable-refresh-rate` per output if that ever cha
 `focus-at-startup` on both M34 and eDP-1: niri focuses in config order, so
 the ultrawide wins when present and the laptop panel is the fallback.
 
+## The desk-2 rig (portable)
+
+Laptop plus two 16" PM1601 panels in portrait, side by side as one 2400x1920
+band. Profile: `cfg/desk-2-portable.kdl` (`display.kdl` symlinks to it).
+
+```
+┌──────────────┬──────────┬──────────┐
+│              │  PM1601  │  PM1601  │   eDP-1     1920x1080  normal  x=0,y=420
+│              │  rot 90  │  rot 90  │   DP-2      1200x1920  rot 90  x=1920,y=0
+│   eDP-1      │ 1200x1920│ 1200x1920│   HDMI-A-1  1200x1920  rot 90  x=3120,y=0
+│  1920x1080   │  (DP-2)  │(HDMI-A-1)│
+│              │          │          │   The laptop is pinned 420 px down so its
+└──────────────┴──────────┴──────────┘   centre (960) meets the band's centre:
+   x=0,y=420      x=1920,0   x=3120,0    no dead corner when the cursor crosses.
+```
+
+All three blocks are identity-keyed and pin their mode string verbatim. The
+`requires:` list names all three panels, so the matcher only claims this profile
+when the whole rig is present — unplug one 16" panel and the watcher leaves the
+current layout alone rather than shuffling the survivors.
+
+**The stale-profile trap this fixed (2026-10-30).** Before this profile existed,
+the portable rig ran with `display.kdl` → `desk-1-home.kdl`, whose identity
+blocks belong to the Sceptre ultrawide that is *not* connected and whose
+connector-keyed fallbacks carried `mode "3440x1440@180.000"`. niri found no such
+mode on a 1920x1200 panel, logged the fallback, and drove it at preferred — so
+the panels looked fine while every position and refresh value in force had been
+written for a different desk. `desk.sh match` reported "no desk profile matches
+connected outputs" and `blankpad-desk-autoswitch.service` therefore died at its
+initial match, leaving the laptop pinned to the wrong profile indefinitely.
+Law: **a desk with no matching profile is not "unchanged", it is silently
+misconfigured** — `desk.sh match` saying "no match" is a defect to fix before
+anything else on that desk behaves strangely.
+
 ## Desk switching
 
 ```mermaid
@@ -80,8 +114,13 @@ graph LR
 - **Manual override:** `Mod+Shift+D` cycles profiles (wrong auto-pick, or
   same panels, new layout).
 - **New desk:** `desk.sh capture` prints connected long names → copy into a
-  new `desk-N-<name>.kdl` (see `desk-2-portable.kdl` skeleton, portable
-  monitor EDID pending first capture).
+  new `desk-N-<name>.kdl` with one identity block per panel (template:
+  [the desk-2 rig](#the-desk-2-rig-portable)).
+- **A dead watcher is a signal, not a crash to ignore:** the unit exits at
+  startup when `desk.sh match` finds no eligible profile, so "no match" on a
+  desk that clearly has panels means a missing profile, not an idle daemon.
+  Check `systemctl --user is-active blankpad-desk-autoswitch` after touching
+  desk profiles.
 - Unit: `blankpad-desk-autoswitch.service` (systemd user,
   `ConditionHost=blankpad`).