feat(snap): add transparent object snap overrides in active commands

Allow users to temporarily override object snaps during active point prompts by typing at least the first 3 letters of any snap mode (e.g. MID, END, CEN, PER, NON). The override activates for the next point pick only and automatically restores running snaps once consumed or cancelled.

src/app/automation.rs

@@ -3477,6 +3477,81 @@ mod tests {
         );
     }
 
+    #[test]
+    fn test_snap_override_typed_in_line_command() {
+        use crate::app::Message;
+        let mut app = OpenCADStudio::new_for_test();
+        app.automation_op(r#"{"op":"new"}"#);
+        {
+            app.tabs[0].scene.selection.borrow_mut().view.vp_size = (1920.0, 1080.0);
+            app.tabs[0].scene.sync_tiles_from_panes(1920.0, 1080.0);
+        }
+
+        // Start LINE
+        let _ = app.update(Message::CommandInput("LINE".to_string()));
+        let _ = app.update(Message::CommandSubmit);
+        assert_eq!(
+            app.tabs[0].active_cmd.as_ref().map(|c| c.name()),
+            Some("LINE")
+        );
+
+        // Turn running osnap off to prove override temporarily enables snapping
+        app.snapper.snap_enabled = false;
+        assert!(!app.snapper.snap_enabled);
+
+        // Type MID at first point prompt
+        let _ = app.update(Message::CommandInput("MID".to_string()));
+        let _ = app.update(Message::CommandSubmit);
+
+        // LINE remains the active command
+        assert_eq!(
+            app.tabs[0].active_cmd.as_ref().map(|c| c.name()),
+            Some("LINE")
+        );
+        // Snapper is now forced on with only Midpoint enabled
+        assert!(app.snapper.snap_enabled);
+        assert_eq!(app.snapper.enabled.len(), 1);
+        assert!(app.snapper.enabled.contains(&crate::snap::SnapType::Midpoint));
+
+        // Submit first point (0,0)
+        let _ = app.update(Message::CommandInput("0,0".to_string()));
+        let _ = app.update(Message::CommandSubmit);
+
+        // Override is consumed by the point commit, restoring snap_enabled == false
+        assert!(!app.snapper.snap_enabled);
+
+        // At next point prompt, type END
+        let _ = app.update(Message::CommandInput("END".to_string()));
+        let _ = app.update(Message::CommandSubmit);
+        assert!(app.snapper.snap_enabled);
+        assert!(app.snapper.enabled.contains(&crate::snap::SnapType::Endpoint));
+
+        // Escape cancels LINE and clears unconsumed snap override
+        let _ = app.update(Message::CommandEscape);
+        assert!(app.tabs[0].active_cmd.is_none());
+        assert!(!app.snapper.snap_enabled);
+    }
+
+    #[test]
+    fn test_snap_override_feed_token() {
+        use crate::app::Message;
+        let mut app = OpenCADStudio::new_for_test();
+        app.automation_op(r#"{"op":"new"}"#);
+        let _ = app.update(Message::CommandInput("LINE".to_string()));
+        let _ = app.update(Message::CommandSubmit);
+
+        app.snapper.snap_enabled = false;
+        let _ = app.feed_active_cmd("CEN");
+        assert!(app.snapper.snap_enabled);
+        assert_eq!(app.snapper.enabled.len(), 1);
+        assert!(app.snapper.enabled.contains(&crate::snap::SnapType::Center));
+
+        let _ = app.feed_active_cmd("5,5");
+        assert!(!app.snapper.snap_enabled);
+
+        let _ = app.update(Message::CommandEscape);
+    }
+
     #[test]
     fn test_open_color_dropdown() {
         use crate::app::Message;

src/app/command_driver/utilities.rs

@@ -583,6 +583,7 @@ impl OpenCADStudio {
             if !self.record_accepted_snap(i, None, None, *point) {
                 return (Task::none(), true);
             }
+            self.snapper.clear_override();
         }
         if default_start {
             let StepInput::Point(point) = &input else {
@@ -1113,6 +1114,27 @@ impl OpenCADStudio {
                 return Task::none();
             }
         }
+        if let Some(override_kind) = crate::snap::parse_snap_override(token) {
+            let is_point_step = !self.tabs[i]
+                .active_cmd
+                .as_ref()
+                .map(|c| c.input_kind().wants_text())
+                .unwrap_or(true)
+                || self.tabs[i]
+                    .active_cmd
+                    .as_ref()
+                    .map(|c| c.point_step_accepts_keywords())
+                    .unwrap_or(false);
+            let not_entity_pick = !self.tabs[i]
+                .active_cmd
+                .as_ref()
+                .map(|c| c.needs_entity_pick())
+                .unwrap_or(false);
+            if is_point_step && not_entity_pick {
+                self.apply_snap_override(override_kind);
+                return Task::none();
+            }
+        }
         if let Some((coord, kind)) = crate::app::helpers::parse_coord(token) {
             // Match the GUI command line: typed coordinates are in the active
             // UCS (relative offsets are rotated by the UCS axes), so a multi-

src/app/commands/mod.rs

@@ -74,6 +74,7 @@ impl OpenCADStudio {
         // A new command collects its own points, so the previous command's
         // accepted snaps must not leak into it.
         self.clear_accepted_snaps();
+        self.snapper.clear_override();
         // Starting a command restarts the right-click cycle, so its first
         // right-click acts as Enter rather than opening the context menu.
         self.tabs[i]

src/app/update/command.rs

@@ -820,6 +820,28 @@ pub(super) fn on_tab_close(&mut self, idx: usize) -> Task<Message> {
                             return self.focus_cmd_input();
                         }
                     }
+                    if let Some(override_kind) = crate::snap::parse_snap_override(&raw) {
+                        let is_point_step = !self.tabs[i]
+                            .active_cmd
+                            .as_ref()
+                            .map(|c| c.input_kind().wants_text())
+                            .unwrap_or(true)
+                            || self.tabs[i]
+                                .active_cmd
+                                .as_ref()
+                                .map(|c| c.point_step_accepts_keywords())
+                                .unwrap_or(false);
+                        let not_entity_pick = !self.tabs[i]
+                            .active_cmd
+                            .as_ref()
+                            .map(|c| c.needs_entity_pick())
+                            .unwrap_or(false);
+                        if is_point_step && not_entity_pick {
+                            self.command_line.input.clear();
+                            self.apply_snap_override(override_kind);
+                            return self.focus_cmd_input();
+                        }
+                    }
                     let text = if free_text {
                         raw
                     } else {
@@ -918,6 +940,7 @@ pub(super) fn on_tab_close(&mut self, idx: usize) -> Task<Message> {
                         self.dyn_coord_absolute = false;
                         self.sync_dyn_fields();
                         self.reset_tracking_after_point();
+                        self.snapper.clear_override();
                         self.push_ucs_to_cmd(i);
                         let result = self.tabs[i].active_cmd.as_mut().map(|c| c.on_point(wcs_pt));
                         if let Some(r) = result {
@@ -1030,6 +1053,7 @@ pub(super) fn on_tab_close(&mut self, idx: usize) -> Task<Message> {
         self.dyn_coord_absolute = false;
         self.sync_dyn_fields();
         self.reset_tracking_after_point();
+        self.snapper.clear_override();
         if let Some((_, dir)) = distance_ray {
             self.snapper.remember_distance_reference(dir);
         }

src/app/update/dynamic.rs

@@ -679,6 +679,7 @@ impl OpenCADStudio {
                         self.dyn_coord_absolute = false;
                         self.sync_dyn_fields();
                         self.reset_tracking_after_point();
+                        self.snapper.clear_override();
                         self.snapper.remember_distance_reference(dir);
                         self.push_ucs_to_cmd(i);
                         let result = self.tabs[i].active_cmd.as_mut().map(|c| c.on_point(pt));
@@ -752,6 +753,7 @@ impl OpenCADStudio {
         self.dyn_coord_absolute = false;
         self.sync_dyn_fields();
         self.reset_tracking_after_point();
+        self.snapper.clear_override();
         self.push_ucs_to_cmd(i);
         let result = self.tabs[i].active_cmd.as_mut().map(|c| c.on_point(pt));
         for f in self.tabs[i].dyn_fields.iter_mut() {

src/app/update/mod.rs

@@ -940,23 +940,12 @@ impl OpenCADStudio {
             }
 
             Message::SnapOverridePick(t) => {
-                self.snap_override_popup = None;
-                self.snapper.set_override(t);
-                let label = crate::snap::ALL_SNAP_MODES
-                    .iter()
-                    .find(|(m, _, _)| *m == t)
-                    .map(|(_, _, l)| *l)
-                    .unwrap_or("Snap");
-                self.command_line
-                    .push_info(crate::tf!("Snap override: {label} (next pick only).").as_ref());
+                self.apply_snap_override(crate::snap::SnapOverrideKind::Mode(t));
                 Task::none()
             }
 
             Message::SnapOverrideNone => {
-                self.snap_override_popup = None;
-                self.snapper.set_override_none();
-                self.command_line
-                    .push_info(crate::t!("Snap override: None (next pick only).").as_ref());
+                self.apply_snap_override(crate::snap::SnapOverrideKind::None);
                 Task::none()
             }
 

src/app/update/viewport_snap.rs

@@ -50,6 +50,30 @@ impl OpenCADStudio {
         self.accepted_snaps.clear();
     }
 
+    /// Apply a transparent one-shot snap override (from typed input or the context menu).
+    pub(crate) fn apply_snap_override(&mut self, kind: crate::snap::SnapOverrideKind) {
+        match kind {
+            crate::snap::SnapOverrideKind::Mode(t) => {
+                self.snap_override_popup = None;
+                self.snapper.set_override(t);
+                let label = crate::snap::ALL_SNAP_MODES
+                    .iter()
+                    .chain(crate::snap::ALL_3D_SNAP_MODES.iter())
+                    .find(|(m, _, _)| *m == t)
+                    .map(|(_, _, l)| *l)
+                    .unwrap_or("Snap");
+                self.command_line
+                    .push_info(crate::tf!("Snap override: {label} (next pick only).").as_ref());
+            }
+            crate::snap::SnapOverrideKind::None => {
+                self.snap_override_popup = None;
+                self.snapper.set_override_none();
+                self.command_line
+                    .push_info(crate::t!("Snap override: None (next pick only).").as_ref());
+            }
+        }
+    }
+
     /// Record the snap a point step just accepted. `snap` is the displayed snap
     /// result (already in the current space's coordinates) or `None` for a free
     /// / typed point; `committed` is the point the command actually received

src/snap.rs

@@ -115,6 +115,76 @@ pub const ALL_3D_SNAP_MODES: &[(SnapType, &str, &str)] = &[
     (SnapType::NearestFace, "✦", "Nearest to face"),
 ];
 
+/// Transparent object snap override kind (single-pick override).
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+pub enum SnapOverrideKind {
+    Mode(SnapType),
+    None,
+}
+
+/// Parses a transparent object snap override keyword (e.g. `MID`, `END`, `CEN`, `NON`).
+///
+/// Requires at least 3 letters matching a supported snap mode or alias.
+/// Leading underscores (e.g. `_MID`) and case variations are permitted.
+pub fn parse_snap_override(input: &str) -> Option<SnapOverrideKind> {
+    let s = input.trim().trim_start_matches('_').to_ascii_lowercase();
+    if s.len() < 3 {
+        return None;
+    }
+    if s.starts_with("end") && "endpoint".starts_with(&s) {
+        return Some(SnapOverrideKind::Mode(SnapType::Endpoint));
+    }
+    if s.starts_with("mid") && "midpoint".starts_with(&s) {
+        return Some(SnapOverrideKind::Mode(SnapType::Midpoint));
+    }
+    if s.starts_with("cen") && ("center".starts_with(&s) || "centre".starts_with(&s)) {
+        return Some(SnapOverrideKind::Mode(SnapType::Center));
+    }
+    if (s.starts_with("gce") && "gcen".starts_with(&s))
+        || (s.starts_with("geo") && ("geocenter".starts_with(&s) || "geometriccenter".starts_with(&s)))
+    {
+        return Some(SnapOverrideKind::Mode(SnapType::GeometricCenter));
+    }
+    if s.starts_with("nod") && "node".starts_with(&s) {
+        return Some(SnapOverrideKind::Mode(SnapType::Node));
+    }
+    if s.starts_with("qua") && "quadrant".starts_with(&s) {
+        return Some(SnapOverrideKind::Mode(SnapType::Quadrant));
+    }
+    if s.starts_with("int") && "intersection".starts_with(&s) {
+        return Some(SnapOverrideKind::Mode(SnapType::Intersection));
+    }
+    if s.starts_with("ext") && "extension".starts_with(&s) {
+        return Some(SnapOverrideKind::Mode(SnapType::Extension));
+    }
+    if s.starts_with("ins") && ("insertion".starts_with(&s) || "insert".starts_with(&s)) {
+        return Some(SnapOverrideKind::Mode(SnapType::Insertion));
+    }
+    if s.starts_with("per") && "perpendicular".starts_with(&s) {
+        return Some(SnapOverrideKind::Mode(SnapType::Perpendicular));
+    }
+    if s.starts_with("tan") && "tangent".starts_with(&s) {
+        return Some(SnapOverrideKind::Mode(SnapType::Tangent));
+    }
+    if s.starts_with("nea") && "nearest".starts_with(&s) {
+        return Some(SnapOverrideKind::Mode(SnapType::Nearest));
+    }
+    if s.starts_with("app")
+        && ("apparent".starts_with(&s)
+            || "apparentintersection".starts_with(&s)
+            || "appint".starts_with(&s))
+    {
+        return Some(SnapOverrideKind::Mode(SnapType::ApparentIntersection));
+    }
+    if s.starts_with("par") && "parallel".starts_with(&s) {
+        return Some(SnapOverrideKind::Mode(SnapType::Parallel));
+    }
+    if s.starts_with("non") && "none".starts_with(&s) {
+        return Some(SnapOverrideKind::None);
+    }
+    None
+}
+
 // ── Snap result ───────────────────────────────────────────────────────────
 
 #[derive(Debug, Clone, Copy)]
@@ -5197,4 +5267,71 @@ mod ext_tests {
         );
         assert!(res_break.is_none(), "cursor over ellipse arc break must NOT snap to tangent");
     }
+
+    #[test]
+    fn test_parse_snap_override() {
+        use super::{parse_snap_override, SnapOverrideKind, SnapType};
+
+        // 3-letter prefixes
+        assert_eq!(parse_snap_override("end"), Some(SnapOverrideKind::Mode(SnapType::Endpoint)));
+        assert_eq!(parse_snap_override("mid"), Some(SnapOverrideKind::Mode(SnapType::Midpoint)));
+        assert_eq!(parse_snap_override("cen"), Some(SnapOverrideKind::Mode(SnapType::Center)));
+        assert_eq!(parse_snap_override("nod"), Some(SnapOverrideKind::Mode(SnapType::Node)));
+        assert_eq!(parse_snap_override("qua"), Some(SnapOverrideKind::Mode(SnapType::Quadrant)));
+        assert_eq!(parse_snap_override("int"), Some(SnapOverrideKind::Mode(SnapType::Intersection)));
+        assert_eq!(parse_snap_override("ext"), Some(SnapOverrideKind::Mode(SnapType::Extension)));
+        assert_eq!(parse_snap_override("ins"), Some(SnapOverrideKind::Mode(SnapType::Insertion)));
+        assert_eq!(parse_snap_override("per"), Some(SnapOverrideKind::Mode(SnapType::Perpendicular)));
+        assert_eq!(parse_snap_override("tan"), Some(SnapOverrideKind::Mode(SnapType::Tangent)));
+        assert_eq!(parse_snap_override("nea"), Some(SnapOverrideKind::Mode(SnapType::Nearest)));
+        assert_eq!(parse_snap_override("app"), Some(SnapOverrideKind::Mode(SnapType::ApparentIntersection)));
+        assert_eq!(parse_snap_override("par"), Some(SnapOverrideKind::Mode(SnapType::Parallel)));
+        assert_eq!(parse_snap_override("non"), Some(SnapOverrideKind::None));
+        assert_eq!(parse_snap_override("geo"), Some(SnapOverrideKind::Mode(SnapType::GeometricCenter)));
+        assert_eq!(parse_snap_override("gce"), Some(SnapOverrideKind::Mode(SnapType::GeometricCenter)));
+
+        // Case insensitivity & leading underscores
+        assert_eq!(parse_snap_override("_MID"), Some(SnapOverrideKind::Mode(SnapType::Midpoint)));
+        assert_eq!(parse_snap_override("_Endpoint"), Some(SnapOverrideKind::Mode(SnapType::Endpoint)));
+        assert_eq!(parse_snap_override("  _NON  "), Some(SnapOverrideKind::None));
+        assert_eq!(parse_snap_override("CEN"), Some(SnapOverrideKind::Mode(SnapType::Center)));
+
+        // Full names and aliases
+        assert_eq!(parse_snap_override("endpoint"), Some(SnapOverrideKind::Mode(SnapType::Endpoint)));
+        assert_eq!(parse_snap_override("midpoint"), Some(SnapOverrideKind::Mode(SnapType::Midpoint)));
+        assert_eq!(parse_snap_override("center"), Some(SnapOverrideKind::Mode(SnapType::Center)));
+        assert_eq!(parse_snap_override("centre"), Some(SnapOverrideKind::Mode(SnapType::Center)));
+        assert_eq!(parse_snap_override("quadrant"), Some(SnapOverrideKind::Mode(SnapType::Quadrant)));
+        assert_eq!(parse_snap_override("intersection"), Some(SnapOverrideKind::Mode(SnapType::Intersection)));
+        assert_eq!(parse_snap_override("perpendicular"), Some(SnapOverrideKind::Mode(SnapType::Perpendicular)));
+        assert_eq!(parse_snap_override("tangent"), Some(SnapOverrideKind::Mode(SnapType::Tangent)));
+        assert_eq!(parse_snap_override("nearest"), Some(SnapOverrideKind::Mode(SnapType::Nearest)));
+        assert_eq!(parse_snap_override("apparent"), Some(SnapOverrideKind::Mode(SnapType::ApparentIntersection)));
+        assert_eq!(parse_snap_override("apparentintersection"), Some(SnapOverrideKind::Mode(SnapType::ApparentIntersection)));
+        assert_eq!(parse_snap_override("appint"), Some(SnapOverrideKind::Mode(SnapType::ApparentIntersection)));
+        assert_eq!(parse_snap_override("parallel"), Some(SnapOverrideKind::Mode(SnapType::Parallel)));
+        assert_eq!(parse_snap_override("insert"), Some(SnapOverrideKind::Mode(SnapType::Insertion)));
+        assert_eq!(parse_snap_override("insertion"), Some(SnapOverrideKind::Mode(SnapType::Insertion)));
+        assert_eq!(parse_snap_override("none"), Some(SnapOverrideKind::None));
+        assert_eq!(parse_snap_override("gcen"), Some(SnapOverrideKind::Mode(SnapType::GeometricCenter)));
+        assert_eq!(parse_snap_override("geometriccenter"), Some(SnapOverrideKind::Mode(SnapType::GeometricCenter)));
+        assert_eq!(parse_snap_override("geocenter"), Some(SnapOverrideKind::Mode(SnapType::GeometricCenter)));
+
+        // Rejection of strings shorter than 3 chars
+        assert_eq!(parse_snap_override("en"), None);
+        assert_eq!(parse_snap_override("mi"), None);
+        assert_eq!(parse_snap_override("ce"), None);
+        assert_eq!(parse_snap_override("p"), None);
+        assert_eq!(parse_snap_override("no"), None);
+        assert_eq!(parse_snap_override("_m"), None);
+        assert_eq!(parse_snap_override(""), None);
+
+        // Non-matching tokens
+        assert_eq!(parse_snap_override("line"), None);
+        assert_eq!(parse_snap_override("circle"), None);
+        assert_eq!(parse_snap_override("10,20"), None);
+        assert_eq!(parse_snap_override("@5<45"), None);
+        assert_eq!(parse_snap_override("undo"), None);
+        assert_eq!(parse_snap_override("close"), None);
+    }
 }