Select Color: one fixed colour book folder instead of a folder list setting

The color_book_dirs setting is gone. Colour books live in color_books in
the config folder (book::folder()), like the other fixed locations;
Options > Files shows it through Folders::color_books. read_all() and
load_from_dialog() use that folder directly.

Co-Authored-By: Claude Opus 5.5 <[email protected]>
Claude-Session: https://claude.ai/code/session_013rGmDUNr1hUf4zo1X3dak8

src/app/mod.rs

@@ -1067,10 +1067,9 @@ pub(super) struct OpenCADStudio {
     // ── Floating panel windows ────────────────────────────────────────────
     /// The open Select Color panel, if any.
     color_picker: Option<crate::ui::color_select::ColorPicker>,
-    /// The built-in colour books and those in `color_book_dirs`, read
-    /// lazily when the Select Color panel opens.
+    /// The built-in colour book and those in the colour book folder, read
+    /// lazily when the Select Color panel first opens.
     color_books: std::sync::Arc<Vec<crate::ui::color_select::book::ColorBook>>,
-    color_book_dirs: Vec<String>,
     color_books_read: bool,
     /// Recently committed real colours, newest first.
     /// ACI and True Color remain semantically distinct even when their RGB matches.
@@ -4793,7 +4792,6 @@ impl OpenCADStudio {
             web_autosave_clear_after: Vec::new(),
             color_picker: None,
             color_books: Default::default(),
-            color_book_dirs: Vec::new(),
             color_books_read: false,
             active_modal: None,
             hyperlink_editor_handles: Vec::new(),

src/app/settings.rs

@@ -636,10 +636,6 @@ pub struct UserSettings {
     /// Blocks palette: library folders or drawings, last used first.
     #[serde(default)]
     pub block_libraries: Vec<String>,
-    /// Folders searched for `.acb` colour books. Books loaded in the Select
-    /// Color panel are copied into the first one.
-    #[serde(default = "default_color_book_dirs")]
-    pub color_book_dirs: Vec<String>,
     /// Blocks palette view: 0 extra large, 1 large, 2 medium, 3 small icons,
     /// 4 details, 5 list.
     #[serde(default = "default_block_view")]
@@ -801,15 +797,6 @@ fn default_grid_major() -> u32 {
     5
 }
 
-/// One folder in the config directory; none on the web, which has no folders.
-fn default_color_book_dirs() -> Vec<String> {
-    #[cfg(not(target_arch = "wasm32"))]
-    if let Some(dir) = crate::config::config_dir() {
-        return vec![dir.join("color_books").display().to_string()];
-    }
-    Vec::new()
-}
-
 fn default_true() -> bool {
     true
 }
@@ -973,7 +960,6 @@ impl Default for UserSettings {
             block_recent: Vec::new(),
             block_favorites: Vec::new(),
             block_libraries: Vec::new(),
-            color_book_dirs: default_color_book_dirs(),
             block_palette_view: 1,
             block_insert: BlockInsertOptions::default(),
             block_mru_list: 50,

src/app/update/file.rs

@@ -868,7 +868,6 @@ impl OpenCADStudio {
             block_recent: self.block_palette.recent.clone(),
             block_favorites: self.block_palette.favorites.clone(),
             block_libraries: self.block_palette.libraries.clone(),
-            color_book_dirs: self.color_book_dirs.clone(),
             block_palette_view: self.block_palette.view as u8,
             block_insert: self.block_palette.options.clone(),
             block_mru_list: self.block_mru_list,
@@ -1047,10 +1046,6 @@ impl OpenCADStudio {
         self.block_palette.recent = s.block_recent.clone();
         self.block_palette.favorites = s.block_favorites.clone();
         self.block_palette.libraries = s.block_libraries.clone();
-        if self.color_book_dirs != s.color_book_dirs {
-            self.color_book_dirs = s.color_book_dirs.clone();
-            self.color_books_read = false;
-        }
         self.block_palette.view =
             crate::ui::window::block_palette::ViewMode::from_u8(s.block_palette_view);
         self.block_palette.set_options(s.block_insert.clone());

src/app/update/mod.rs

@@ -11935,9 +11935,7 @@ impl OpenCADStudio {
                         self.update(Message::ColorWindowPick(color, name))
                     }
                     Some(crate::ui::color_select::Outcome::LoadBook) => Task::perform(
-                        crate::ui::color_select::book::load_from_dialog(
-                            self.color_book_dirs.first().cloned(),
-                        ),
+                        crate::ui::color_select::book::load_from_dialog(),
                         Message::ColorBookLoaded,
                     ),
                     Some(crate::ui::color_select::Outcome::Cancel) => {
@@ -12070,16 +12068,14 @@ impl OpenCADStudio {
         document.layers.get(layer).map(|layer| layer.color)
     }
 
-    /// Read the built-in colour books and every `.acb` in the colour book
-    /// folders, once until the folders change. A book in a folder replaces a
-    /// built-in one of the same name.
+    /// Read the built-in colour book and every `.acb` in the colour book
+    /// folder, once per session. A book in the folder replaces a built-in
+    /// one of the same name.
     fn read_color_books(&mut self) {
         if std::mem::replace(&mut self.color_books_read, true) {
             return;
         }
-        self.color_books = std::sync::Arc::new(crate::ui::color_select::book::read_all(
-            &self.color_book_dirs,
-        ));
+        self.color_books = std::sync::Arc::new(crate::ui::color_select::book::read_all());
     }
 
     /// Colour the selected objects (or set the current colour when nothing

src/app/view/modal.rs

@@ -373,6 +373,8 @@ impl OpenCADStudio {
                                         .map(|_| std::env::temp_dir().display().to_string()),
                                     fonts: crate::io::font_repo::fonts_dir()
                                         .map(|p| p.display().to_string()),
+                                    color_books: crate::ui::color_select::book::folder()
+                                        .map(|p| p.display().to_string()),
                                 }
                             }
                             #[cfg(target_arch = "wasm32")]
@@ -381,7 +383,6 @@ impl OpenCADStudio {
                             }
                         },
                         &self.qnew_template,
-                        &self.color_book_dirs,
                         self.double_click_block_refedit,
                         self.double_click_block_attedit,
                         self.cursor_type,