Implement Vega-Lite rendering with error handling and dynamic library loading

docs/dev-plan.md

@@ -105,17 +105,26 @@ Astrolabe is a focused tool for managing, editing, and previewing Vega-Lite visu
 
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-### **Phase 4: Vega-Lite Rendering**
+### **Phase 4: Vega-Lite Rendering** ✅ **COMPLETE**
 **Goal**: Live preview of visualizations
 
-- [ ] Load Vega-Embed from CDN
-- [ ] Create render function that takes spec from editor
-- [ ] Add debounced auto-render on editor change
-- [ ] Display rendered chart in right panel
-- [ ] Handle rendering errors gracefully (show in preview panel)
+- [x] Load Vega-Embed from CDN
+- [x] Create render function that takes spec from editor
+- [x] Add debounced auto-render on editor change
+- [x] Display rendered chart in right panel
+- [x] Handle rendering errors gracefully (show in preview panel)
 
 **Deliverable**: Editor → live chart pipeline working with auto-refresh
 
+**Key Achievements**:
+- Successfully resolved AMD loader conflicts with Monaco Editor
+- Implemented UMD build loading with temporary AMD disable/restore
+- Added 1.5s debounced rendering for smooth editing experience
+- Created comprehensive error handling with user-friendly messages
+- Established working editor → JSON parsing → Vega-Lite rendering pipeline
+- Sample bar chart loads and renders immediately on page load
+- Live preview updates automatically as user edits JSON specification
+
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 ### **Phase 5: Data Model + LocalStorage**
@@ -275,5 +284,5 @@ Astrolabe is a focused tool for managing, editing, and previewing Vega-Lite visu
 
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-**Current Phase**: Phase 4 - Vega-Lite Rendering
+**Current Phase**: Phase 5 - Data Model + LocalStorage
 **Status**: Ready to begin implementation