feat(ui): the Page tool draws liquid guides from the rulers

Chris Cicchino's "Adobe InDesign – Page Tool and Liquid Layout" (11:00–
13:30) drags guides out of the rulers with the Page tool on a
guide-based page: "these guides are a little bit different... they are a
dashed line, a cyan dashed line" - liquid guides, which let the objects
they cross stretch with the page. DesignCraft drew liquid guides dashed
and applied them, but a guide could only become liquid through the
Liquid Layout panel's list: ruler drags always made ruler guides.

- canvas: with the Page tool, a page guide dragged from a ruler is a
  liquid guide; its preview is dashed while it's dragged.
- engine: guide.add takes `liquid`.

Co-Authored-By: Claude Opus 5.5 <[email protected]>

ROADMAP.md

@@ -129,6 +129,7 @@ list) · [roadmap.md](docs/roadmap.md) (milestones, plan) · [parity-checklist.m
 
 Newest first.
 
+- **2026-10-14** · With the Page tool, a guide dragged from a ruler is a liquid guide (dashed), as in InDesign; guide-based pages stretch the objects it crosses. No readiness percentage change.
 - **2026-10-12** · macOS Dock Quit uses the same unsaved-document prompts as window and menu Quit. Repeated requests keep the current answers; Cancel retains every tab and unsaved recovery checkpoint, and completed Save/Don't Save answers exit through the ordinary event loop. No readiness percentage change.
 - **2026-10-12** · Orderly native exit writes the latest recovery state after finalizing current quit approvals; incomplete or stale plans keep their documents, and Undo to the saved state clears stale recovery. Unavailable or failed recovery is reported. Cancelable macOS Dock Quit remains open (#544). No readiness percentage change.
 - **2026-10-12** · Recovered documents keep a checkpoint until saved, closed or reverted, including a second crash before autosave. Restarted document IDs and explicit recovery folders preserve other snapshots; failed republishing retains the original. No readiness percentage change.

crates/engine/src/cmd/guides.rs

@@ -21,7 +21,7 @@ pub fn specs() -> Vec<CommandSpec> {
             "New Guide",
             [],
             None,
-            "{orientation: horizontal|vertical, position (spread coordinate), spread?, page? (index in the spread; default: the page under `at` or the position), at? (the other coordinate), spreadGuide?: bool} → {page, index}",
+            "{orientation: horizontal|vertical, position (spread coordinate), spread?, page? (index in the spread; default: the page under `at` or the position), at? (the other coordinate), spreadGuide?: bool, liquid?: bool (a liquid guide, as the Page tool draws from the rulers)} → {page, index}",
             has_doc,
             add
         ),
@@ -98,6 +98,7 @@ fn add(s: &mut Session, p: &Value) -> Result<Value> {
     let pos = finite_number(p, "position", "guide.add")?.ok_or_else(|| bad("guide.add", "missing position"))?;
     let r = super::spread_param(p, "guide.add")?;
     let spread_guide = p.get("spreadGuide").and_then(Value::as_bool).unwrap_or(false);
+    let liquid = p.get("liquid").and_then(Value::as_bool).unwrap_or(false);
     let d = &s.doc()?.doc;
     let pi = match optional_usize(p, "page", "guide.add")? {
         Some(pi) => pi,
@@ -114,7 +115,14 @@ fn add(s: &mut Session, p: &Value) -> Result<Value> {
     s.edit(|d, _| {
         let sp = d.spread_mut(r).ok_or_else(|| bad("guide.add", "no such spread"))?;
         let pg = sp.pages.get_mut(pi).ok_or_else(|| bad("guide.add", "no such page"))?;
-        pg.guides.push(Guide { orientation: o, position: pos, spread: spread_guide, locked: false, layer: Some(layer), liquid: false });
+        pg.guides.push(Guide {
+            orientation: o,
+            position: pos,
+            spread: spread_guide,
+            locked: false,
+            layer: Some(layer),
+            liquid: liquid && !spread_guide,
+        });
         Ok(json!({"page": pi, "index": pg.guides.len() - 1}))
     })
 }

crates/ui-egui/src/canvas.rs

@@ -301,7 +301,12 @@ pub fn show(app: &mut DesignApp, ui: &mut egui::Ui) {
                 designcraft_doc::Orientation::Horizontal => (pos2(rect.min.x, p.y), pos2(rect.max.x, p.y)),
                 designcraft_doc::Orientation::Vertical => (pos2(p.x, rect.min.y), pos2(p.x, rect.max.y)),
             };
-            painter.line_segment([a, b], Stroke::new(1.0, col));
+            // A new guide from the rulers with the Page tool is a liquid guide: dashed.
+            if g.from.is_none() && app.session.tool_id() == "page" {
+                dashed(&painter, a, b, Stroke::new(1.0, col), 6.0, 3.0);
+            } else {
+                painter.line_segment([a, b], Stroke::new(1.0, col));
+            }
         }
         draw_frames(app, &painter, &xf, &doc, &layout);
         if app.ui.hidden_characters {
@@ -1760,7 +1765,10 @@ fn guide_drag(app: &mut DesignApp, ui: &mut egui::Ui, resp: &egui::Response, rec
             let _ = app.run("guide.move", json!({"spread": r, "page": pi, "index": gi, "position": pos_of(sp)}));
         }
         (None, true, Some((r, sp, on_page))) => {
-            let mut params = json!({"spread": r, "orientation": orient, "position": pos_of(sp), "at": sp.x, "spreadGuide": on_page.is_none()});
+            // The Page tool draws liquid guides from the rulers.
+            let liquid = app.session.tool_id() == "page" && on_page.is_some();
+            let mut params =
+                json!({"spread": r, "orientation": orient, "position": pos_of(sp), "at": sp.x, "spreadGuide": on_page.is_none(), "liquid": liquid});
             if let Some(pi) = on_page {
                 params["page"] = json!(pi);
             }
@@ -1791,6 +1799,42 @@ mod tests {
         h
     }
 
+    /// A primary-button drag from `a` to `b` over a few frames.
+    fn drag(h: &mut Harness<'_, DesignApp>, a: Pos2, b: Pos2) {
+        h.hover_at(a);
+        h.step();
+        h.event(egui::Event::PointerButton { pos: a, button: egui::PointerButton::Primary, pressed: true, modifiers: Default::default() });
+        h.step();
+        for k in 1..=4 {
+            h.hover_at(a + (b - a) * (k as f32 / 4.0));
+            h.step();
+        }
+        h.event(egui::Event::PointerButton { pos: b, button: egui::PointerButton::Primary, pressed: false, modifiers: Default::default() });
+        h.run_steps(3);
+    }
+
+    #[test]
+    fn the_page_tool_draws_liquid_guides_from_the_rulers() {
+        // Chris Cicchino's Page Tool and Liquid Layout video (11:00): with the Page tool, a guide
+        // dragged from the ruler is a liquid guide (dashed).
+        let mut app = DesignApp::new(designcraft_engine::Session::new(), crate::Services::default());
+        app.run("file.new", json!({})).unwrap();
+        app.session.set_tool("page");
+        let mut h = harness(app);
+        let r = h.state().canvas_rect.unwrap();
+        let guides = |h: &Harness<'_, DesignApp>| h.state().session.doc().unwrap().doc.spreads[0].pages[0].guides.clone();
+        drag(&mut h, pos2(r.center().x, r.min.y - 8.0), r.center());
+        let g = guides(&h);
+        assert_eq!(g.len(), 1, "{g:?}");
+        assert!(g[0].liquid && g[0].orientation == designcraft_doc::Orientation::Horizontal);
+        // With the Selection tool it's a ruler guide.
+        h.state_mut().session.set_tool("selection");
+        drag(&mut h, pos2(r.center().x, r.min.y - 8.0), r.center() + vec2(0.0, 40.0));
+        let g = guides(&h);
+        assert_eq!(g.len(), 2);
+        assert!(!g[1].liquid);
+    }
+
     fn right_click(h: &mut Harness<'_, DesignApp>, p: Pos2) {
         h.hover_at(p);
         h.step();