browser.visibility hides and shows sketches, bodies, construction geometry and origin items (items: ids or names, or a whole folder; visible: bool), so agents can hide helper sketches over MCP. What is hidden moved from the egui UI state into the engine session (view state: not saved, not an undo step); the desktop eye toggles and menus use it, headless renders and fit leave hidden items out, and document.inspect, sketch.inspect and ui.inspect report visibility. ui.set still accepts hiddenBodies, hiddenOrigin, hiddenSketches and shownSketches. Tests: helper sketches hide and show in the engine (hostile input changes nothing) and through MCP only

crates/engine/src/lib.rs

@@ -168,6 +168,22 @@ pub struct Session {
     pub section: Option<(Vec3, Vec3)>,
     /// Surface analysis shading the model (zebra, draft, curvature map).
     pub analysis: Option<SurfaceAnalysis>,
+    /// What is hidden or shown in the view (`browser.visibility`).
+    pub visibility: Visibility,
+}
+
+/// Items hidden or shown one by one (view state, not part of the design and not an undo step).
+#[derive(Clone, Debug, Default, PartialEq, serde::Serialize, serde::Deserialize)]
+#[serde(default)]
+pub struct Visibility {
+    /// Bodies by name.
+    pub hidden_bodies: Vec<String>,
+    /// Origin items (O, X, Y, Z, XY, XZ, YZ) and construction geometry, by name.
+    pub hidden_origin: Vec<String>,
+    /// Sketches by feature id.
+    pub hidden_sketches: Vec<u64>,
+    /// Finished sketches shown although a feature uses them.
+    pub shown_sketches: Vec<u64>,
 }
 
 /// A way of shading the model's faces to judge their shape (view state, not part of the design).
@@ -219,6 +235,7 @@ impl Session {
             clipboard: Vec::new(),
             section: None,
             analysis: None,
+            visibility: Visibility::default(),
         }
     }
 
@@ -360,6 +377,7 @@ impl Session {
             clipboard: self.clipboard.clone(),
             section: None,
             analysis: None,
+            visibility: Visibility::default(),
         }
     }