From 0864db94945b3074c659bca012e406c73a713b70 Mon Sep 17 00:00:00 2001
From: Adithya Shankaran <72570811+adikshan11@users.noreply.github.com>
Date: Fri, 6 Nov 2026 14:21:54 +0530
Subject: [PATCH] Keep the other library when two names share a file name
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A library called COM¹ is saved as COM¹-, which can be the file of a library
really called COM¹-, and the numbered file one of them then gets can be asked
for by a third name. Saving one replaced the other. Each now gets a free file
name, and saving it again goes back to that file.
---
 crates/engine/src/cmd/swatchlib.rs   | 23 ++++++++++++++++++++++-
 crates/engine/src/tests/swatchlib.rs | 27 +++++++++++++++++++++++++++
 2 files changed, 49 insertions(+), 1 deletion(-)

diff --git a/crates/engine/src/cmd/swatchlib.rs b/crates/engine/src/cmd/swatchlib.rs
index 8e929f14d..9ecec6c67 100644
--- a/crates/engine/src/cmd/swatchlib.rs
+++ b/crates/engine/src/cmd/swatchlib.rs
@@ -211,7 +211,28 @@ impl<L: LibraryFile> Libraries<L> {
                 .user_dir()
                 .ok_or_else(|| bad(cmd, "no user library folder here (save with a path, or without one to get the data)"))?
                 .to_string();
-            let file = library_file_name(name, ext);
+            let mut file = library_file_name(name, ext);
+            // `COM¹` is saved as `COM¹-`, which can be another library's own name, and a library put
+            // under a numbered name holds a file another name can ask for: such a file is kept.
+            self.rescan();
+            let device = crate::file_access::is_device_name;
+            let id = format!("user/{file}").to_lowercase();
+            let fallback = |other: &str| library_file_name(other, ext).to_lowercase() != file.to_lowercase();
+            if self
+                .extra
+                .iter()
+                .any(|e| e.info.id.to_lowercase() == id && e.lib.name() != name && (device(name) || device(e.lib.name()) || fallback(e.lib.name())))
+            {
+                // Saved again, it goes back to the file it was given the first time.
+                let own = self.extra.iter().find(|e| e.info.category == "user" && e.lib.name() == name && extension(&e.info.id) == extension(&file));
+                file = match own.and_then(|e| e.info.id.strip_prefix("user/")) {
+                    Some(own) => own.to_string(),
+                    None => {
+                        let mut taken: HashSet<String> = library_files(&dir, L::EXTS).iter().map(|p| file_name(p).to_lowercase()).collect();
+                        free_name(&file, &mut taken)
+                    }
+                };
+            }
             let path = std::path::Path::new(&dir).join(&file).to_string_lossy().to_string();
             // The app's own folder, under a name made safe: no root applies.
             crate::file_access::unconfined(|| create_dir(&dir).and_then(|()| write_file(&path, bytes)))?;
diff --git a/crates/engine/src/tests/swatchlib.rs b/crates/engine/src/tests/swatchlib.rs
index 18d2ecd33..23980c5d5 100644
--- a/crates/engine/src/tests/swatchlib.rs
+++ b/crates/engine/src/tests/swatchlib.rs
@@ -765,6 +765,33 @@ fn a_pattern_library_adds_only_the_picked_pattern_and_it_undoes_and_saves() {
     assert_eq!(back.swatch("Checkerboard").map(|w| &w.paint), doc(&s).swatch("Checkerboard").map(|w| &w.paint));
 }
 
+/// A device name is saved with a `-` after it, which can be another library's own name: neither
+/// library replaces the other, and saving either again replaces only itself.
+#[test]
+fn a_library_named_like_a_device_keeps_the_library_with_its_file_name() {
+    for (first, second) in [("COM¹", "COM¹-"), ("COM¹-", "COM¹"), ("com¹", "COM¹-")] {
+        let dir = temp_dir("device-collision");
+        let mut s = session();
+        s.swatch_libraries.set_user_dir(Some(dir.to_string_lossy().to_string()));
+        let save =
+            |s: &mut Session, name: &str| run(s, "swatch.library.save", json!({"user": true, "name": name}))["library"].as_str().unwrap().to_string();
+        let a = save(&mut s, first);
+        let b = save(&mut s, second);
+        assert_ne!(a, b);
+        assert_eq!(save(&mut s, first), a, "saving {first} again replaces {first}");
+        assert_eq!(save(&mut s, second), b, "saving {second} again replaces {second}");
+        assert_eq!(s.swatch_libraries.get(&a).unwrap().1.name, first);
+        assert_eq!(s.swatch_libraries.get(&b).unwrap().1.name, second);
+        // The name of the numbered file the second one got is a third library's own name.
+        let third = b.strip_prefix("user/").unwrap().strip_suffix(".vcswatches").unwrap().to_string();
+        let c = save(&mut s, &third);
+        assert!(c != a && c != b, "{third}: {c}");
+        assert_eq!(save(&mut s, &third), c, "saving {third} again replaces {third}");
+        assert_eq!(s.swatch_libraries.get(&b).unwrap().1.name, second);
+        let _ = std::fs::remove_dir_all(&dir);
+    }
+}
+
 /// #3602: a library titled with a Windows device name is saved under a name that is not one.
 #[test]
 fn a_library_file_name_is_never_a_windows_device_name() {