Summary of Changes

Backend (backend/app/api/routes/archives.py):
  - Added filament_colors extraction from slice_info.config in 3MF files
  - Maps filament IDs (1-based) to tool numbers (0-based)

  Frontend (frontend/src/components/GcodeViewer.tsx):
  1. Multi-color support: Pass extrusionColor as array of CSS color strings for multi-color prints
  2. Bambu T-command filtering: Filter out special Bambu commands (T255, T1000, T1001, T65535, T65279) that corrupt tool state
  3. Initial tool: Prepend T0 to ensure initial tool is set correctly
  4. Disable gradient: Set disableGradient: true for multi-color to preserve actual filament colors (the gradient was turning black into gray/white)
  5. Disable topLayerColor: Don't set topLayerColor for multi-color (it overrides per-tool colors)

  Key fixes for Bambu G-code compatibility:
  - Bambu uses special T commands (T1000, T65535, etc.) that aren't real tool changes
  - The gcode-preview library's brightness gradient was modifying colors based on layer index

  Commit message suggestion:
  Add multi-color filament support to G-code viewer

  - Extract filament colors from 3MF slice_info.config
  - Pass color array to gcode-preview for tool-based coloring
  - Filter Bambu special T commands (T1000, T65535, etc.)
  - Disable gradient to preserve actual filament colors

frontend/src/api/client.ts

@@ -1380,6 +1380,7 @@ export const api = {
       has_model: boolean;
       has_gcode: boolean;
       build_volume: { x: number; y: number; z: number };
+      filament_colors: string[];
     }>(`/archives/${id}/capabilities`),
   // Project Page
   getArchiveProjectPage: (id: number) =>