From b26bd3d47230a9d34c846b79b46ef2eb4649e596 Mon Sep 17 00:00:00 2001
From: dotCooCoo <RobertLeeLW@gmail.com>
Date: Thu, 5 Nov 2026 19:28:36 -0800
Subject: [PATCH] Reject invalid Guide Lock parameters

---
 crates/engine/src/cmd/docmenu.rs    |  4 ++--
 crates/engine/src/tests/menucmds.rs | 17 +++++++++++++++++
 docs/mcp.md                         |  1 +
 3 files changed, 20 insertions(+), 2 deletions(-)

diff --git a/crates/engine/src/cmd/docmenu.rs b/crates/engine/src/cmd/docmenu.rs
index fc146fdec..5b1b4300b 100644
--- a/crates/engine/src/cmd/docmenu.rs
+++ b/crates/engine/src/cmd/docmenu.rs
@@ -14,7 +14,7 @@ use super::pathops::Beside;
 use super::select::{first_selectable, is_selectable, selectable_ids, walk_selectable};
 use super::{
     CommandSpec, EngineError, Point, Result, Session, bad, bool_or, checked_ids_param, cmd, f64_or, f64_req, has_doc, has_selection, id_param, ok,
-    str_param,
+    str_param, switch_or,
 };
 
 pub fn specs() -> Vec<CommandSpec> {
@@ -716,7 +716,7 @@ fn release_guides(s: &mut Session, p: &Value) -> Result<Value> {
 }
 
 fn lock_guides(s: &mut Session, p: &Value) -> Result<Value> {
-    let v = p.get("locked").and_then(Value::as_bool).unwrap_or(!s.menu.guides_locked);
+    let v = switch_or(p, "locked", !s.menu.guides_locked, "view.guides.lock")?;
     s.menu.guides_locked = v;
     // Locked guides can't stay selected, ruler guides or guide paths, in any open document
     // ([`Session::select`] lets those go in the active one).
diff --git a/crates/engine/src/tests/menucmds.rs b/crates/engine/src/tests/menucmds.rs
index 450baabc1..82dc07e55 100644
--- a/crates/engine/src/tests/menucmds.rs
+++ b/crates/engine/src/tests/menucmds.rs
@@ -3539,6 +3539,23 @@ fn ruler_guides_and_lock() {
     assert!(s.execute("guide.remove", &json!({"index": 0})).is_err());
 }
 
+#[test]
+fn invalid_guide_lock_parameters_keep_guides_selected() {
+    let mut s = session();
+    s.execute("guide.add", &json!({"vertical": false, "pos": 50})).unwrap();
+    s.execute("guide.select", &json!({"indexes": [0]})).unwrap();
+    let before_undo = s.doc().unwrap().history.undo.len();
+    for params in [json!({"locked": "false"}), json!({"locked": 1})] {
+        assert!(s.execute("view.guides.lock", &params).is_err(), "accepted {params}");
+        assert!(!s.guides_locked(), "locked guides for {params}");
+        assert_eq!(s.doc().unwrap().selection.guides, vec![0], "cleared selection for {params}");
+        assert_eq!(s.doc().unwrap().history.undo.len(), before_undo, "recorded undo for {params}");
+    }
+    // Left out, or null as for every command, it toggles.
+    assert_eq!(s.execute("view.guides.lock", &json!(null)).unwrap(), json!({"locked": true}));
+    assert_eq!(s.execute("view.guides.lock", &json!({"locked": null})).unwrap(), json!({"locked": false}));
+}
+
 /// #1534: Lock Guides locks the paths made into guides too: they can't be selected (so neither
 /// moved, reshaped nor deleted), by a click, a marquee or Select All, and locking lets them go.
 #[test]
diff --git a/docs/mcp.md b/docs/mcp.md
index 4934da0c7..87ac5085c 100644
--- a/docs/mcp.md
+++ b/docs/mcp.md
@@ -1631,6 +1631,7 @@ step. With guides selected, `edit.clear` (Delete) deletes them and `object.nudge
 View › Guides › Lock Guides (`view.guides.lock`) deselects them and the paths made into guides, in every open
 document, and refuses these commands until unlocked. While it is on, a command that selects art, such as `edit.undo`,
 `edit.redo`, `object.exitIsolation`, `object.unlockAll`, `object.showAll` or `edit.paste`, leaves the guides out.
+`view.guides.lock` rejects a `locked` value that is not a boolean. Omitting `locked` toggles the current value.
 
 `view.guides.release {index?, ids?}` (View › Guides › Release Guides) turns guides into paths → `{count}`. With
 `index` it releases that ruler guide, and with `ids` it releases those guide paths (and the guide paths inside them).