fix(ui): a right-click between the pages anchors no page's menu; the guard finds router readers

Found in review:
- **A right-click off the pages.** Between the pages or beside one, no page took the
  right-click, but the page menu still opened over the page view, on the last anchor: Delete
  page, Paste and Copy Image acted on a page right-clicked long before. This was so on `main`
  too. The anchor is now cleared on every right-click before the pages set it, so off the pages
  the menu acts on the current page.
- **The guard** took a file as a page module only by marks a router read doesn't need. A file
  that reads `.router.` is one too, so its router reads are checked.
- **Docs.** egui ends a press's drag when any button is released, not when a second goes down.
  `link_ui::hit` takes the tip from the link it found rather than looking it up again.

Tests: a right-click between the pages clears the anchor, seen failing without the fix. A
planted router read in an unlisted file fails the guard.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

crates/ui-egui/src/canvas.rs

@@ -1645,6 +1645,9 @@ fn draw_pages(
     if resp.secondary_clicked() {
         // Set again below when the right-click lands on a link.
         view.links.context = None;
+        // Set again below by the page right-clicked: a right-click off the pages (between them,
+        // beside one) anchors no page's menu, which then acts on the current page.
+        view.comments.context_at = None;
         let mut over_image = false;
         if tool == QuickTool::EditText {
             let pointer_pos = ptr.pos;

crates/ui-egui/src/canvas/page_input.rs

@@ -105,9 +105,9 @@ pub(super) fn page_tool_input(ui: &mut egui::Ui, view: &mut DocView, frame: &mut
         _ => false,
     };
     // A right-click while the primary button is held (a comment moved, a box drawn) leaves the
-    // selections that press acts on alone; egui ends the press's own interaction when another button
-    // goes down, so the button is what tells. A touch's long press, which egui reports as a
-    // right-click with the finger still down, opens its menu.
+    // selections that press acts on alone. egui ends the press's own interaction when any button is
+    // released, the right-click's own frame included, so the button is what tells. A touch's long
+    // press, which egui reports as a right-click with the finger still down, opens its menu.
     let press_held = ptr.primary_down && !resp.long_touched();
     let context = frame.right_click_on(xf.rect).and_then(|p| right_click(&hits, &under, view, p, press_held));
     // A mark already placed takes its own press (comments, below), as does one being moved on this

crates/ui-egui/src/canvas/page_pointer/tests.rs

@@ -191,10 +191,10 @@ const PAGE_MODULES: [&str; 37] = [
 ];
 
 /// What a file that acts on the pages uses: the pointer, a tool's or the comments' page context,
-/// what a press is to a page, or the router's hits and owners. Such a file is a page module. One
-/// that acts on the pages through the page view's response and a bare point alone uses none of
-/// them (`canvas/image_pick.rs`): PAGE_MODULES lists it by hand.
-const PAGE_MODULE_MARKS: [&str; 5] = ["PagePointer", "PageToolContext", "PageCx", "PagePress", "page_router::"];
+/// what a press is to a page, the router's hits and owners, or the router itself. Such a file is a
+/// page module. One that acts on the pages through the page view's response and a bare point alone
+/// uses none of them (`canvas/image_pick.rs`): PAGE_MODULES lists it by hand.
+const PAGE_MODULE_MARKS: [&str; 6] = ["PagePointer", "PageToolContext", "PageCx", "PagePress", "page_router::", ".router."];
 
 /// The router's own files, which define what page modules use.
 const ROUTER_FILES: [&str; 3] = ["canvas/page_pointer.rs", "canvas/page_router.rs", "canvas/page_cursor.rs"];

crates/ui-egui/src/tools/link_ui.rs

@@ -70,12 +70,14 @@ pub(crate) fn hit(xf: &PageXform, info: &DocInfo, page: usize, links: &[LinkItem
     if !xf.rect.contains(p) {
         return None;
     }
-    let index = if tool == QuickTool::Link {
-        links.iter().rfind(|l| l.page == page && screen_rect(xf, info, page, l.rect).expand(LINK_TOOL_MARGIN).contains(p))?.index
+    let (index, link) = if tool == QuickTool::Link {
+        let index = links.iter().rfind(|l| l.page == page && screen_rect(xf, info, page, l.rect).expand(LINK_TOOL_MARGIN).contains(p))?.index;
+        (index, info.links.iter().find(|l| l.page == page && l.index == index))
     } else {
-        info.links.iter().rfind(|l| l.page == page && xf.user_rect(info, page, l.rect).contains(p))?.index
+        let link = info.links.iter().rfind(|l| l.page == page && xf.user_rect(info, page, l.rect).contains(p))?;
+        (link.index, Some(link))
     };
-    let tip = info.links.iter().find(|l| l.page == page && l.index == index).map(|l| target_label(info, &l.target));
+    let tip = link.map(|l| target_label(info, &l.target));
     let declines_drag = tool == QuickTool::Link;
     Some(Hit { tip, declines_drag, ..Hit::new(Owner::Link { index }, Layer::Link, egui::CursorIcon::PointingHand) })
 }

crates/ui-egui/tests/it/pointer.rs

@@ -1708,3 +1708,20 @@ fn a_fill_and_sign_click_places_nothing_while_a_mark_is_moved() {
     mouse_click(&mut h, blank);
     assert_eq!(marks(&h), before, "no mark is placed");
 }
+
+/// A right-click between the pages anchors no page's menu, so Delete page and Paste act on the
+/// current page. The menu used to keep the anchor of the last right-click on a page.
+#[test]
+fn a_right_click_between_the_pages_anchors_no_pages_menu() {
+    let mut h = open(two_pages_pdf(), "100", false);
+    h.run_steps(2);
+    h.state_mut().views[0].comments.context_at = Some((0, [10.0, 10.0]));
+    let (one, two) = {
+        let v = &h.state().views[0];
+        (v.page_screen_rect(0).expect("page 1 on screen"), v.page_screen_rect(1).expect("page 2 on screen"))
+    };
+    let gap = egui::pos2(one.center().x, (one.max.y + two.min.y) / 2.0);
+    assert!(!one.contains(gap) && !two.contains(gap), "between the pages: {one:?} {two:?}");
+    right_click(&mut h, gap);
+    assert_eq!(h.state().views[0].comments.context_at, None);
+}