From 6259448c3912e01d0af860a09898443b0e2773ad Mon Sep 17 00:00:00 2001
From: NetterSilver <133535268+Silvertree2010@users.noreply.github.com>
Date: Sun, 25 Oct 2026 13:01:25 +0100
Subject: [PATCH] Reset stroke weight to zero when the stroke colour is removed

Fixes #4109

Co-Authored-By: Claude Haiku 5.5 <noreply@anthropic.com>
Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>
---
 crates/engine/src/cmd/paint.rs              |  7 +++++++
 crates/engine/tests/it/stroke_visibility.rs | 12 ++++++++++++
 2 files changed, 19 insertions(+)

diff --git a/crates/engine/src/cmd/paint.rs b/crates/engine/src/cmd/paint.rs
index 2c527a820..f6e555892 100644
--- a/crates/engine/src/cmd/paint.rs
+++ b/crates/engine/src/cmd/paint.rs
@@ -504,6 +504,13 @@ fn apply_paint(s: &mut Session, p: &Value, paint: Paint, fill: bool) -> Result<V
             let new_paint = keep_pattern_xf(&paint, p, n.appearance.paint_at(index, fill));
             let placed = place_paint(&new_paint, p, item_paint_bounds(n, index, fill));
             n.appearance.set_paint_at(index, fill, placed);
+            if !fill
+                && paint.is_none()
+                && let Some(stroke) = n.appearance.stroke_at_mut(index)
+            {
+                // A stroke without paint has no weight; painting it again restores the 1 pt default.
+                stroke.width = 0.0;
+            }
             Ok(())
         },
         |d, changed| {
diff --git a/crates/engine/tests/it/stroke_visibility.rs b/crates/engine/tests/it/stroke_visibility.rs
index 8f9ecdff0..310770c39 100644
--- a/crates/engine/tests/it/stroke_visibility.rs
+++ b/crates/engine/tests/it/stroke_visibility.rs
@@ -116,3 +116,15 @@ fn appearance_panel_stroke_colour_restores_an_unpainted_zero_width_stroke() {
     s.execute("appearance.setItem", &json!({"index": 1, "color": "#0000ff"})).unwrap();
     assert_eq!(width(&s, id), 0.0, "a painted stroke keeps an explicit zero width");
 }
+
+#[test]
+fn removing_the_stroke_colour_resets_the_weight_to_zero() {
+    let (mut s, id) = fixture();
+    s.execute("paint.setStroke", &json!({"color": "#000000"})).unwrap();
+    s.execute("stroke.set", &json!({"weight": 10})).unwrap();
+    s.execute("paint.setStroke", &json!({"none": true})).unwrap();
+    assert_eq!(width(&s, id), 0.0);
+    assert_eq!(s.shown_stroke().unwrap().width, 0.0);
+    s.execute("paint.setStroke", &json!({"color": "#ee2222"})).unwrap();
+    assert_eq!(width(&s, id), 1.0);
+}