fix(editor): handle duplicate wallpaper basenames without a sync loop

frontend/src/App.svelte

@@ -64,21 +64,18 @@
         setExtendedColors,
         setNativeColors,
         setIconTheme,
-        setAdjustments,
         setColor,
         setExtendedColor,
         setAppOverride,
-        setAppOverrides,
-        setAdditionalImages,
-        setLightMode,
-        setExtractionMode,
+        applyBackendState,
         getThemeSnapshot,
         getThemeSignature,
         getLastAppliedSignature,
         getIsApplying,
         getIsAdjusting,
         getIsExtracting,
         setLastExtractedPath,
+        type BackendStatePayload,
     } from '$lib/stores/theme.svelte';
     import {debounce} from '$lib/utils/debounce';
     import {STORAGE_KEYS} from '$lib/constants/storage';
@@ -156,10 +153,15 @@
             .catch(() => {});
     }, STATE_SYNC_DEBOUNCE_MS);
 
+    // Send only snapshots that differ from the last mirrored state, so a
+    // backend push of equal values does not cause another SyncState call.
+    let lastSyncedSignature = '';
     $effect(() => {
-        syncStateToBackend(
-            getThemeSnapshot() as unknown as main.SyncStateRequest
-        );
+        const snapshot = getThemeSnapshot();
+        const signature = getThemeSignature(snapshot);
+        if (signature === lastSyncedSignature) return;
+        lastSyncedSignature = signature;
+        syncStateToBackend(snapshot as unknown as main.SyncStateRequest);
     });
 
     // Arming records the initial state without applying it. Queuing is not an
@@ -553,55 +555,12 @@
                     }
                 } catch {}
 
-                // Listen for IPC remote control state changes
-                EventsOn(
-                    'ipc-state-changed',
-                    (state: {
-                        palette?: string[];
-                        extendedColors?: Record<string, string>;
-                        nativeColors?: Record<string, string>;
-                        iconTheme?: {mode?: string; id?: string};
-                        lightMode?: boolean;
-                        mode?: string;
-                        wallpaper?: string;
-                        wallpaperBlur?: boolean;
-                        adjustments?: import('$lib/types/theme').Adjustments;
-                        appOverrides?: Record<string, Record<string, string>>;
-                        additionalImages?: string[];
-                    }) => {
-                        if (state.palette && state.palette.length >= 16) {
-                            setPalette(state.palette);
-                        }
-                        if (state.extendedColors) {
-                            setExtendedColors(state.extendedColors);
-                        }
-                        if (state.nativeColors) {
-                            setNativeColors(state.nativeColors);
-                        }
-                        if (state.iconTheme)
-                            setIconTheme(state.iconTheme, true);
-                        if (state.lightMode !== undefined) {
-                            setLightMode(state.lightMode);
-                        }
-                        if (state.mode) {
-                            setExtractionMode(state.mode);
-                        }
-                        if (state.wallpaper !== undefined) {
-                            setWallpaperPath(state.wallpaper);
-                        }
-                        if (state.wallpaperBlur !== undefined)
-                            setWallpaperBlur(state.wallpaperBlur, true);
-                        if (state.adjustments) {
-                            setAdjustments(state.adjustments);
-                        }
-                        if (state.appOverrides) {
-                            setAppOverrides(state.appOverrides);
-                        }
-                        if (state.additionalImages) {
-                            setAdditionalImages(state.additionalImages);
-                        }
-                    }
-                );
+                // Listen for IPC remote control state changes. The applier
+                // skips fields that already match, so an echo of our own
+                // SyncState cannot re-arm the sync effect above.
+                EventsOn('ipc-state-changed', (state: BackendStatePayload) => {
+                    applyBackendState(state);
+                });
             } catch {}
         })();
     });

frontend/src/lib/actions/blueprintActions.ts

@@ -12,6 +12,7 @@ import {
     setAdditionalImages,
     setLastExtractedPath,
     setLockedColor,
+    dedupeAdditionalImages,
 } from '$lib/stores/theme.svelte';
 
 export function loadBlueprintIntoEditor(bp: Blueprint): void {
@@ -36,11 +37,25 @@ export function loadBlueprintIntoEditor(bp: Blueprint): void {
     setWallpaperPath(bp.palette.wallpaper ?? '');
     setWallpaperBlur(!!bp.palette.wallpaperBlur, true);
     setAppOverrides(bp.appOverrides ?? {});
-    setAdditionalImages(bp.palette.additionalImages ?? []);
+    // Blueprints can list the same wallpaper twice, or two wallpapers sharing a
+    // filename; the backend stages them into one flat directory and rejects
+    // such a set with a basename collision, so drop the unusable entries and
+    // tell the user instead of failing the later apply.
+    const requestedImages = bp.palette.additionalImages ?? [];
+    const uniqueImages = dedupeAdditionalImages(
+        requestedImages,
+        bp.palette.wallpaper ?? ''
+    );
+    setAdditionalImages(uniqueImages);
     setLastExtractedPath(bp.palette.wallpaper ?? '');
     for (let i = 0; i < 16; i++) {
         setLockedColor(i, bp.palette.lockedColors?.includes(i) ?? false);
     }
     setActiveTab('editor');
-    showToast(`Loaded: ${bp.name}. Review, then apply when ready.`);
+    const skippedImages = requestedImages.length - uniqueImages.length;
+    showToast(
+        skippedImages > 0
+            ? `Loaded: ${bp.name}. Skipped ${skippedImages} duplicate wallpaper${skippedImages === 1 ? '' : 's'}.`
+            : `Loaded: ${bp.name}. Review, then apply when ready.`
+    );
 }

frontend/src/lib/components/editor/AdditionalImages.svelte

@@ -43,8 +43,11 @@
             );
             const path = await OpenFileDialog();
             if (path) {
-                addAdditionalImage(path);
-                showToast('Image added');
+                showToast(
+                    addAdditionalImage(path)
+                        ? 'Image added'
+                        : 'Skipped: the theme already has a wallpaper with that filename'
+                );
             }
         } catch {}
     }
@@ -73,7 +76,9 @@
     </div>
 
     <div class="grid grid-cols-2 gap-2 px-3.5 pb-3.5 pt-3">
-        {#each getAdditionalImages() as img (img)}
+        <!-- Unkeyed on purpose. A keyed each throws on a repeated path,
+             and that error stopped every later effect (issue #130). -->
+        {#each getAdditionalImages() as img}
             <div
                 class="border-border group relative aspect-video overflow-hidden border bg-black"
             >

frontend/src/lib/components/favorites/FavoritesView.svelte

@@ -175,8 +175,11 @@
             showToast('Already in additional images');
             return;
         }
-        addAdditionalImage(localPath);
-        showToast('Added to additional images');
+        showToast(
+            addAdditionalImage(localPath)
+                ? 'Added to additional images'
+                : 'Skipped: the theme already has a wallpaper with that filename'
+        );
     }
 
     async function resolvePreviewSrc(fav: Favorite): Promise<string> {

frontend/src/lib/components/github/GitHubCard.svelte

@@ -84,8 +84,11 @@
                     showToast('Already in additional images');
                     return;
                 }
-                addAdditionalImage(path);
-                showToast('Added to additional images');
+                showToast(
+                    addAdditionalImage(path)
+                        ? 'Added to additional images'
+                        : 'Skipped: the theme already has a wallpaper with that filename'
+                );
             } else {
                 setWallpaperPath(path);
                 setActiveTab('editor');

frontend/src/lib/components/local/LocalBrowser.svelte

@@ -199,8 +199,11 @@
             showToast('Already in additional images');
             return;
         }
-        addAdditionalImage(path);
-        showToast('Added to additional images');
+        showToast(
+            addAdditionalImage(path)
+                ? 'Added to additional images'
+                : 'Skipped: the theme already has a wallpaper with that filename'
+        );
     }
 
     async function handleFavorite(wp: Wallpaper) {

frontend/src/lib/components/wallhaven/WallpaperCard.svelte

@@ -75,8 +75,11 @@
                 showToast('Already in additional images');
                 return;
             }
-            addAdditionalImage(localPath);
-            showToast('Added to additional images');
+            showToast(
+                addAdditionalImage(localPath)
+                    ? 'Added to additional images'
+                    : 'Skipped: the theme already has a wallpaper with that filename'
+            );
         } catch {
             showToast('Failed to download wallpaper');
         }