feat: size: prefix, external auto-detection, auto-disable stale monitors

- size:WxH and size:WxH@R resolution for config names
- auto-detection of external monitors when external list is empty (any non-internal display)
- ensureCleanLayout: explicitly disable connected monitors not in target layout
- update docs (README, example.yaml) for all three features

README.md

@@ -57,6 +57,7 @@ Plugs into your dock — external monitors turn on, built-in turns off. Unplug
 | 5 | **Graceful shutdown** — optionally restores portable layout on SIGTERM |
 | 6 | **Socket reconnect** — exponential backoff if compositor socket drops |
 | 7 | **Atomic config writes (Hyprland)** — temp file + rename prevents config corruption |
+| 8 | **Auto-disable stale monitors** — monitors connected but absent from the target layout are explicitly disabled (prevents external displays from staying on after switching to portable mode) |
 
 ---
 
@@ -142,13 +143,17 @@ restore_on_exit: true
 # External monitors that trigger docked mode.
 # Plain name: matches connector (DP-1, HDMI-A-1).
 # desc: prefix: matches by monitor description (survives port rename).
-external:
+# Optional — if omitted or empty, the daemon auto-detects external monitors:
+# any display whose connector is not eDP-/LVDS-/DSI- is treated as external.
+external:  # optional
   - desc:Dell Inc. DELL U2723QE
   - DP-9
   - DP-10
 
 # Monitor layouts for each mode.
 # "portable" and "docked" are required.
+# Monitors not listed in a mode are automatically disabled (prevents
+# external displays from staying on when switching to portable mode).
 modes:
   portable:
     monitors:
@@ -172,6 +177,11 @@ modes:
         scale: 1.0
       - name: eDP-1
         enabled: false          # turn off laptop screen when docked
+      - name: size:1920x1080@60  # resolve by resolution + refresh rate
+        enabled: true
+        mode: preferred
+        position: auto
+        scale: 1.0
 
 # Shell commands run after a layout change.
 # Commands run concurrently, failures are logged but never crash the daemon.
@@ -185,17 +195,19 @@ hooks:
 
 ### Monitor matching
 
-Two match modes, supported in both the `external` list and the `modes` section:
+Three match modes for the `modes` section (the `external` list supports plain names and `desc:`):
 
 | Syntax | Matches | Use case |
 |---|---|---|
 | `DP-1` | Exact connector name | Simple setups, built-in displays |
-| `desc:Dell U2723QE` | Substring in monitor description | Survives port rename across different docks |
+| `desc:Dell U2723QE` | Substring in monitor description or serial | Survives port rename across different docks |
+| `size:2560x1440` | Exact pixel dimensions | Two identical monitors with same resolution |
+| `size:2560x1440@165` | Dimensions + refresh rate | Disambiguate identical models |
 
 Sway description format: `make model serial_widthxheight` (with serial omitted if `Unknown`).  
 Run `hyprctl monitors all` (Hyprland) or `swaymsg -t get_outputs` (Sway) to see your monitor names and descriptions.
 
-**desc: in modes** — when a monitor name in `modes` uses the `desc:` prefix, the daemon resolves it to the actual connector name at runtime. Ambiguous matches (a desc matching multiple monitors) cause an error.
+**desc: and size: in modes** — when a monitor name in `modes` uses `desc:` or `size:`, the daemon resolves it to the actual connector name at runtime. Ambiguous matches (a prefix matching multiple monitors with identical resolution) cause an error. For `size:`, add `@R` (refresh rate) to disambiguate monitors with the same resolution. Unresolvable names also cause an error.
 
 ### Backend-specific configuration
 
@@ -337,7 +349,7 @@ Check the hook command works from a terminal first. Hooks run via `sh -c`, so sh
 
 ### Monitor names changed after reboot
 
-Use `desc:` prefix matching instead of connector names. This survives port renames across different docks and reboots.
+Use `desc:` or `size:` prefix matching instead of connector names. Both survive port renames across different docks and reboots.
 
 **Hyprland:** `hyprctl monitors all` to see descriptions.  
 **Sway:** `swaymsg -t get_outputs` to see names, make/model, serial, and native resolution.
@@ -351,6 +363,8 @@ modes:
     monitors:
       - name: desc:Dell Inc. DELL U2723QE   # also works here
         enabled: true
+      - name: size:2560x1440@165            # match by dimensions + refresh
+        enabled: true
 ```
 
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