fix(idle): skip DPMS-off when docked (#127 mitigation)

Blanking the only live output in dock mode led to a brick where wake and
even VT switch failed. Skip hypridle's 10m dpms off when any laptop
internal (eDP/LVDS/DSI) is present but not enabled; lock at 5m remains.
Undocked still blanks. Document LATER revisit for intentional
DPMS-when-docked once wake is proven.

V1: nix flake check --no-build. V3: docked idle stays lit under lock.

agent/BACKLOG.md

@@ -55,16 +55,21 @@ or (b) undock → `nomarchy-display-transition undock` re-enabling the
 panel. Both failed. `after_sleep_cmd` only does `hyprctl dispatch dpms on`
 and never re-enables a disabled internal.
 
-**Progress 2026-07-15 (no-SSH path + recovery hardening):** undock/enable
-always end with `dpms on`; hypridle `on-resume` / `after_sleep` run
-`nomarchy-display-wake` (dpms + zero-output undock rescue + auto-dump);
-`nomarchy-display-dump` + SUPER+SHIFT+D + TTY (`Ctrl+Alt+F3`) so capture
-does not need SSH. V3 still needs a real docked idle repro.
+**Progress 2026-07-15:**
+- Recovery tooling: undock ends with `dpms on`; `nomarchy-display-wake` /
+  `nomarchy-display-dump` (SUPER+SHIFT+D; TTY if it works).
+- **Mitigation (shipped):** do **not** DPMS-off when docked — if any
+  laptop internal (eDP/LVDS/DSI) exists in `monitors all` but is not
+  enabled, the 10 min listener skips blanking. Lock at 5 min still runs;
+  undocked laptops still DPMS-off as before. Bernardo: Ctrl+Alt+F3 did
+  not yield a usable TTY on the original brick, so prevention > dump path.
+- **Revisit later (LATER):** intentional DPMS-when-docked once wake is
+  proven trustworthy (monitor power-save without a brick).
 
-**Pass:** docked on AC, idle past lock + DPMS; external KB/mouse restores
-the external; if the external is unplugged while black, eDP comes back
-without reboot; journal shows display-watch undock `result=ok` when the
-cable leaves. Capture steps in HARDWARE-QUEUE (TTY dump preferred).
+**Pass (current mitigation):** docked on AC, idle past 10+ min → external
+stays lit under hyprlock (journal: `dpms-off skipped: docked`); undocked
+still blanks at 10 min and wakes on input. Full original pass (wake after
+DPMS-while-docked) deferred to the LATER revisit.
 
 ## NEXT
 
@@ -131,6 +136,14 @@ offline ISO's behaviour untouched (`checks.*` for the offline path stay green).
 
 ## LATER
 
+- **DPMS when docked (revisit #127):** today we **skip** display blanking
+  while any laptop internal is present-but-disabled (dock/clamshell), so
+  idle only locks. That avoids blanking the sole external and the brick
+  where wake/TTY failed (2026-07-15). Revisit when we want monitor
+  power-save on dock again: re-enable DPMS-off for that mode only if
+  `nomarchy-display-wake` (or better) reliably restores the external and
+  undock-while-black restores eDP on the AMD dock setup — without
+  depending on SSH. Until then, leave the skip in `modules/home/idle.nix`.
 - **Wallpapers artifact split** (ROADMAP § Faster switches — decided,
   deferred): pinned `Nomarchy-wallpapers` input so a state write stops
   re-copying 86 MB. Follow-on: pre-built theme variants if switches are