fix(display): #142 — dock mode is an intent, and survives a rebuild

Every rebuild while docked re-lit the panel and threw a workspace onto
it. Not forgetfulness: a rebuild PERFORMS an undock. Dock mode lived only
in the compositor (`keyword monitor <internal>, disable`, nothing written
down), the config's only monitor line is the catch-all
`monitor=,preferred,auto,1`, and rewriting the config makes Hyprland
reload it — re-enabling every output. Our own undock path already uses
`hyprctl reload` as exactly that hammer (hardware-proven 2026-07-14).

The watcher could not rescue it: reconcile diffs `monitors all`, which
lists disabled outputs, so the connected set is identical across the flip
— structurally blind, the blind spot of rounds 4-5's "the output set is
the truth".

So the intent is recorded where every other setting lives —
settings.display.dockMode, in-flake, menu-writable — written at the one
choke point both menu and watcher pass through (transition: dock → true,
undock → false, `enable` of an internal → false, because "Screen on" IS
leaving dock mode and must not be undone a second later). The watcher
re-asserts it as a tick invariant rather than an event reaction, which is
what makes the reload case work; auto_dock was already idempotent, so it
costs one `hyprctl monitors` per tick.

The trap avoided: baking the disable into the config would survive a
reload and hand a user with no external a zero-output session at login —
the #100/#127 brick. The config cannot know what is plugged in, so it
keeps defaulting to "everything on" and the re-assert is gated on an
external being present.

Verified: 9/9 gates unit-tested by driving the REAL generated function
against stubs (incl. no-external → never re-dock, profile active → yield,
already-docked → no churn), plus the state write/read round-trip on a
throwaway checkout so the live flake was untouched. V3 queued — needs a
relogin, the watcher is exec-once.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

agent/BACKLOG.md

@@ -253,53 +253,6 @@ Recommend (a) + (b) together if the patch stays small: file it upstream, carry
 it until it lands, delete on the release that fixes it. `[human]` for whether
 a source-built rofi is a price worth paying.
 
-### 142. A rebuild while docked undoes dock mode (the panel comes back, a workspace jumps to it)
-
-Bernardo 2026-07-16: every rebuild while docked lands in the undocked state —
-laptop panel back on, a workspace moved onto it — and he re-picks **Dock mode**
-in the Display menu by hand. Diagnosed statically on the dev box (no session
-disruption needed; our own code already proves each step):
-
-1. **Dock mode is runtime-only.** `nomarchy-display-transition dock` ends with
-   `hyprctl keyword monitor <internal>, disable` (`hyprland.nix:205`) — a live
-   compositor command. Nothing writes it down: his `state.json` has no display
-   key at all, so dock mode is the one display setting outside the in-flake
-   state, which is exactly why it cannot survive anything.
-2. **Any config reload re-enables everything.** The generated config's only
-   monitor line is the catch-all `monitor=,preferred,auto,1` (live
-   hyprland.conf:175 — he has no `displayProfiles`), so a reload turns every
-   output back on, `eDP-1` included, and Hyprland puts a workspace on the
-   output that just appeared. We do not have to guess that a reload does this:
-   the **undock** path uses `hyprctl reload` deliberately, as the hammer that
-   re-enables an inert disabled panel, hardware-proven 2026-07-14
-   (`hyprland.nix:225`). A rebuild reloads the config and therefore *performs
-   an undock*, precisely and by construction.
-3. **The watcher cannot see it happen.** `reconcile` diffs `outputs()` =
-   `hyprctl monitors all` (`:505`), which lists **disabled** monitors too. So
-   the connected set is byte-identical before and after the flip, `cur !=
-   known_outputs` is false, and reconcile returns having done nothing. The
-   watcher tracks connect/disconnect and is structurally blind to
-   enable/disable — the blind spot in round 4/5's "the output set, not the
-   event, is the truth" (ROADMAP § Docking rounds 4–5).
-
-**Shape, and the trap in the obvious fix.** The tempting move is to bake the
-disable into the config (state → `monitor=eDP-1,disable`) so a reload preserves
-it. **Do not** without a guard: a persisted disable with no external attached
-is a zero-output session at login — the black brick #100 and #127 are both
-about. The config is evaluated with no knowledge of what is plugged in, so it
-must keep defaulting to "everything on". Better: persist the *intent*
-(`settings.display.dockMode`, in-flake, menu-writable — the philosophy this
-currently violates) and let the **watcher** re-assert it, since only it knows
-what is live. That needs reconcile to also track the *enabled* set, so
-"internal came back on while an external is present and the state says docked"
-becomes an event it can act on — which fixes the reload case and any other
-path that silently re-enables the panel. Gate re-assertion on an external
-actually being present, never on the state key alone.
-
-Pass = docked, `nomarchy-home` (and `nomarchy-rebuild`) → panel stays off, no
-workspace moves, no menu trip; undocked rebuild unchanged; unplug while the
-state says docked still restores the panel.
-
 ### 120. A netinstall ISO, next to the fat offline one
 
 Bernardo 2026-07-14, after seeing the measured size: **keep the current ISO