From 896ad29936bf665b0178bf46697d7d71967e086a Mon Sep 17 00:00:00 2001
From: jess <jess@else-if.org>
Date: Tue, 12 May 2026 20:06:57 -0700
Subject: [PATCH] add_segment_with_marker using closest_node

---
 crates/femm-doc/src/edit.rs | 106 ++++++++++++++++++++++++++++++++----
 1 file changed, 94 insertions(+), 12 deletions(-)

diff --git a/crates/femm-doc/src/edit.rs b/crates/femm-doc/src/edit.rs
index a0c00dd..29f05da 100644
--- a/crates/femm-doc/src/edit.rs
+++ b/crates/femm-doc/src/edit.rs
@@ -141,20 +141,53 @@ impl FemmDoc {
 
     /// auto-tolerance for intersection-node coalescing, derived from the node bounding box.
     fn bbox_tolerance(&self) -> f64 {
-        if self.nodes.len() < 2 {
-            return 1.0e-8;
+        nodes_bbox_tolerance(&self.nodes)
+    }
+
+    /// rebuilds every list through the PSLG-aware add primitives, catching crossings missed by incremental edits.
+    pub fn enforce_pslg(&mut self) {
+        let old_nodes        = std::mem::take(&mut self.nodes);
+        let old_segments     = std::mem::take(&mut self.segments);
+        let old_arcs         = std::mem::take(&mut self.arcs);
+        let old_block_labels = std::mem::take(&mut self.block_labels);
+
+        let tol = nodes_bbox_tolerance(&old_nodes);
+
+        // dedupes by position with metadata preserved.
+        for n in &old_nodes {
+            let mut duplicate = false;
+            for existing in &self.nodes {
+                if (existing.x - n.x).hypot(existing.y - n.y) < tol {
+                    duplicate = true;
+                    break;
+                }
+            }
+            if !duplicate {
+                self.nodes.push(n.clone());
+            }
         }
-        let mut xmin = f64::INFINITY;
-        let mut xmax = f64::NEG_INFINITY;
-        let mut ymin = f64::INFINITY;
-        let mut ymax = f64::NEG_INFINITY;
-        for n in &self.nodes {
-            xmin = xmin.min(n.x); xmax = xmax.max(n.x);
-            ymin = ymin.min(n.y); ymax = ymax.max(n.y);
+
+        for s in old_segments {
+            let p0 = (old_nodes[s.n0 as usize].x, old_nodes[s.n0 as usize].y);
+            let p1 = (old_nodes[s.n1 as usize].x, old_nodes[s.n1 as usize].y);
+            let (Some(n0), Some(n1)) = (
+                self.closest_node(p0.0, p0.1),
+                self.closest_node(p1.0, p1.1),
+            ) else { continue };
+            self.add_segment_with_marker(n0 as i32, n1 as i32, &s.boundary_marker);
         }
-        let dx = xmax - xmin;
-        let dy = ymax - ymin;
-        (dx * dx + dy * dy).sqrt() * BBOX_TOLERANCE_FRAC
+
+        for a in old_arcs {
+            let p0 = (old_nodes[a.n0 as usize].x, old_nodes[a.n0 as usize].y);
+            let p1 = (old_nodes[a.n1 as usize].x, old_nodes[a.n1 as usize].y);
+            let (Some(n0), Some(n1)) = (
+                self.closest_node(p0.0, p0.1),
+                self.closest_node(p1.0, p1.1),
+            ) else { continue };
+            self.add_arc_segment(n0 as i32, n1 as i32, a.arc_length);
+        }
+
+        self.block_labels = old_block_labels;
     }
 
     /// adds an arc segment between two node indices, sweeping `arc_length_deg` degrees.
@@ -285,6 +318,24 @@ impl FemmDoc {
     }
 }
 
+/// auto-tolerance derived from the bounding box of a node slice.
+fn nodes_bbox_tolerance(nodes: &[Node]) -> f64 {
+    if nodes.len() < 2 {
+        return 1.0e-8;
+    }
+    let mut xmin = f64::INFINITY;
+    let mut xmax = f64::NEG_INFINITY;
+    let mut ymin = f64::INFINITY;
+    let mut ymax = f64::NEG_INFINITY;
+    for n in nodes {
+        xmin = xmin.min(n.x); xmax = xmax.max(n.x);
+        ymin = ymin.min(n.y); ymax = ymax.max(n.y);
+    }
+    let dx = xmax - xmin;
+    let dy = ymax - ymin;
+    (dx * dx + dy * dy).sqrt() * BBOX_TOLERANCE_FRAC
+}
+
 /// Euclidean distance from (px, py) to the segment between (ax, ay) and (bx, by).
 fn point_to_segment_distance(px: f64, py: f64, ax: f64, ay: f64, bx: f64, by: f64) -> f64 {
     let dx = bx - ax;
@@ -337,6 +388,37 @@ mod tests {
         assert_eq!(touches_mid, 2);
     }
 
+    #[test]
+    fn enforce_pslg_splits_first_segment_at_late_intersection() {
+        // horizontal added first stays whole; vertical second, its split inserts node 4 at origin.
+        // enforce_pslg now re-adds both segments fresh; with node 4 already in place, both
+        // get split through it, ending at 4 segments touching the origin node.
+        let mut d = doc_with_corners();
+        assert!(d.add_segment(0, 1));
+        assert!(d.add_segment(2, 3));
+        assert_eq!(d.segments.len(), 3, "before enforce: one whole, one split");
+
+        d.enforce_pslg();
+
+        assert_eq!(d.nodes.len(), 5, "no node added or merged by enforce");
+        assert_eq!(d.segments.len(), 4, "both originals now split at the origin");
+        let touches_origin = d.segments.iter().filter(|s| s.n0 == 4 || s.n1 == 4).count();
+        assert_eq!(touches_origin, 4);
+    }
+
+    #[test]
+    fn enforce_pslg_preserves_segment_boundary_marker() {
+        let mut d = FemmDoc::default();
+        d.add_node(0.0, 0.0, 0.0);
+        d.add_node(1.0, 0.0, 0.0);
+        assert!(d.add_segment_with_marker(0, 1, "outer"));
+
+        d.enforce_pslg();
+
+        assert_eq!(d.segments.len(), 1);
+        assert_eq!(d.segments[0].boundary_marker, "outer");
+    }
+
     #[test]
     fn crossing_second_segment_splits_at_intersection() {
         // horizontal (-1,0)->(1,0) added first stays whole.