Overlay: set_margin order + click handler no longer kills the badge

- set_margin (wayland_layer.rs:234): correct arg order to
  (top, right, bottom, left). The previous code passed rect.x as
  the right margin, a no-op under TOP+LEFT anchoring, so the
  overlay's x offset was silently dropped. Comment updated to
  document the protocol's true shape.

- click handler (wayland_layer.rs:466): drop 'state.exited = true'
  after send_swap. Flipping exited destroyed the badge but left
  OverlayHub.by_slot still holding the slot, so the hub refused to
  respawn it. The compositor's zwlr_layer_surface::Closed event
  is the only path that drives thread teardown — the click now
  just fires the swap IPC and returns.

- CHANGELOG entries.

cargo test 96+/0; clippy clean.

CHANGELOG.md

@@ -70,3 +70,14 @@
   `layout-apply` against the desktop when only a terminal (or any
   unrelated window) is open.
 - **Profile:** `Character` derives `Default` (needed for the padding).
+
+- **Overlay:** `set_margin` arguments corrected to `(top, right, bottom,
+  left)`. The previous `(rect.y, rect.x, 0, 0)` passed `rect.x` as the
+  *right* margin, which is a no-op under TOP+LEFT anchoring — so the
+  overlay's x offset was silently dropped. Now `(y, 0, 0, x)` which
+  pushes the surface down by `y` and right by `x`.
+- **Overlay:** Left-click on a slot no longer sets `state.exited = true`.
+  Doing so dropped the badge and left `OverlayHub.by_slot` still
+  holding the slot, so the hub refused to respawn it. The compositor's
+  `zwlr_layer_surface::Closed` event is the only path that tears the
+  live thread down — click just sends the swap IPC and returns.

src/wayland_layer.rs

@@ -229,9 +229,12 @@ fn run(slot: u32, rect: OverlayRect, ipc_sock: PathBuf) -> anyhow::Result<()> {
     layer.set_anchor(zwlr_layer_surface_v1::Anchor::Top | zwlr_layer_surface_v1::Anchor::Left);
     layer.set_size(rect.w.max(1) as u32, rect.h.max(1) as u32);
     layer.set_exclusive_zone(-1);
-    // Margins encode the offset: with TOP+LEFT anchor, a positive top
+    // zwlr_layer_surface::set_margin is (top, right, bottom, left).
-    // margin pushes the surface down; positive left pushes it right.
+    // With TOP+LEFT anchor: top margin pushes the surface down, left
-    layer.set_margin(rect.y.max(0), rect.x.max(0), 0, 0);
+    // margin pushes it right. (Earlier versions of this code passed
+    // rect.x as the right margin, which is a no-op when only TOP+LEFT
+    // are anchored.)
+    layer.set_margin(rect.y.max(0), 0, 0, rect.x.max(0));
     layer.set_keyboard_interactivity(zwlr_layer_surface_v1::KeyboardInteractivity::None);
     state.surface = Some(surface.clone());
     state.layer_surface = Some(layer);
@@ -463,7 +466,12 @@ impl Dispatch<wl_pointer::WlPointer, ()> for OverlayState {
                 && matches!(btn_state, wayland_client::WEnum::Value(wl_pointer::ButtonState::Pressed))
             {
                 send_swap(state.slot, &state.ipc_sock);
-                state.exited = true;
+                // NOTE: do not flip `state.exited = true` here. Doing so
+                // destroys the badge and `OverlayHub.by_slot` still holds
+                // the slot, so the hub refuses to respawn it (it thinks
+                // the slot is already served). The compositor's
+                // zwlr_layer_surface::Closed event is the only path that
+                // should tear down the live thread.
             }
         }
     }