From 56ad84266dabe5b2b6db9ccc634e361b8d4dac0c Mon Sep 17 00:00:00 2001
From: dotCooCoo <RobertLeeLW@gmail.com>
Date: Sat, 7 Nov 2026 06:15:28 -0800
Subject: [PATCH] Color management: color.gamutCheck rejects a colors param
 that is not a list

A colors value that is not an array, such as "#fff" or 5, was ignored and the command checked the selection or the whole document instead. It is now an error. A null colors still checks the selection or document, as an omitted one does.
---
 crates/engine/src/cmd/colormgmt.rs   |  6 +++++-
 crates/engine/src/tests/colormgmt.rs | 15 +++++++++++++++
 docs/mcp.md                          |  8 ++++----
 3 files changed, 24 insertions(+), 5 deletions(-)

diff --git a/crates/engine/src/cmd/colormgmt.rs b/crates/engine/src/cmd/colormgmt.rs
index ccc5d4ece..37ccc3004 100644
--- a/crates/engine/src/cmd/colormgmt.rs
+++ b/crates/engine/src/cmd/colormgmt.rs
@@ -683,7 +683,11 @@ fn convert_color(_: &mut Session, p: &Value) -> Result<Value> {
 
 fn gamut_check(s: &mut Session, p: &Value) -> Result<Value> {
     let mut cols: Vec<Color> = vec![];
-    if let Some(a) = p.get("colors").and_then(Value::as_array) {
+    let colors = p.get("colors").filter(|v| !v.is_null());
+    if let Some(v) = colors.filter(|v| !v.is_array()) {
+        return Err(bad("color.gamutCheck", format!("bad color {v}")));
+    }
+    if let Some(a) = colors.and_then(Value::as_array) {
         for v in a {
             cols.push(color_value(v).ok_or_else(|| bad("color.gamutCheck", format!("bad color {v}")))?);
         }
diff --git a/crates/engine/src/tests/colormgmt.rs b/crates/engine/src/tests/colormgmt.rs
index 1ca956794..4ce1ba466 100644
--- a/crates/engine/src/tests/colormgmt.rs
+++ b/crates/engine/src/tests/colormgmt.rs
@@ -631,3 +631,18 @@ fn set_spot_refuses_a_param_of_the_wrong_type() {
     s.execute("swatch.setSpot", &json!({"name": "Ink", "spot": null})).unwrap();
     assert!(s.doc().unwrap().doc.swatch("Ink").unwrap().spot, "a null `spot` is the default, true");
 }
+
+#[test]
+fn gamut_check_refuses_colors_that_are_not_a_list() {
+    let _g = GLOBAL.lock().unwrap_or_else(|e| e.into_inner());
+    let mut s = session();
+    rect(&mut s, 0.0, 0.0, 10.0, 10.0, json!("#0000ff"));
+    s.execute("select.set", &json!({"ids": []})).unwrap();
+    refused(&mut s, "color.gamutCheck", json!({"colors": "#00ff00"}), "bad color \"#00ff00\"");
+    refused(&mut s, "color.gamutCheck", json!({"colors": 5}), "bad color 5");
+    refused(&mut s, "color.gamutCheck", json!({"colors": {"c": 100, "m": 0, "y": 0, "k": 0}}), "bad color");
+    // A null list checks the document, as an omitted one does.
+    let r = s.execute("color.gamutCheck", &json!({"colors": null})).unwrap();
+    assert_eq!(r, s.execute("color.gamutCheck", &json!({})).unwrap());
+    assert!(r["outOfGamut"].as_array().unwrap().iter().any(|v| v["hex"] == "#0000ff"), "{r}");
+}
diff --git a/docs/mcp.md b/docs/mcp.md
index c978252f4..d953a310d 100644
--- a/docs/mcp.md
+++ b/docs/mcp.md
@@ -662,10 +662,10 @@ them. `grays: "black"` puts RGB greys with R = G = B on the black plate instead,
 Convert to Grayscale before the switch would give); other colors convert as usual. The reply's `changed` counts the
 colors that changed in the art, symbols, graph designs and pattern tiles; it does not count the colors of graphic
 styles and brushes.
-`edit.colorSettings`, `file.documentColorMode`, `color.convert`, `color.loadProfile`, `color.removeProfile`,
-`view.proofSetup`, `view.proofColors`, `view.overprintPreview`, `view.separationsPreview` and `swatch.setSpot` reject a
-param of the wrong type, such as `"bpc": "no"`, `"on": 1` or `"to": 5`, and change nothing. Omitting a param or giving
-null keeps its default.
+`edit.colorSettings`, `file.documentColorMode`, `color.convert`, `color.gamutCheck`, `color.loadProfile`,
+`color.removeProfile`, `view.proofSetup`, `view.proofColors`, `view.overprintPreview`, `view.separationsPreview` and
+`swatch.setSpot` reject a param of the wrong type, such as `"bpc": "no"`, `"on": 1`, `"to": 5` or `"colors": "#fff"`,
+and change nothing. Omitting a param or giving null keeps its default.
 
 SVG import keeps what the canvas edits live. `<pattern>` becomes a pattern swatch. A `<symbol>` with `<use>` becomes a
 symbol (named after its `data-name`, else its id) with an instance per `<use>`; a `<use>` that shows it differently