feat: implement Phase 6.4 - Bundle Optimisation with comprehensive analysis

  Phase 6.4 Bundle Optimisation complete with excellent results:
  - Bundle size: 60.09 KB compressed (10.6x under 700 KB grant requirement)
  - Margin: 639.91 KB under budget
  - Modular exports: core (59.61 KB), media (9.79 KB), full (60.09 KB)
  - Tree-shaking efficiency: 13.4%

  Implementation:
  - Added esbuild for bundle analysis
  - Created bundle analysis script (scripts/analyze-bundle.js)
  - Added npm script: npm run analyze-bundle
  - Generated comprehensive reports (BUNDLE_ANALYSIS.md, bundle-analysis.json)
  - Lazy loading via dynamic imports (index.lazy.ts)
  - Package.json sideEffects: false for tree-shaking

  Analysis shows:
  - 295 input files bundled efficiently
  - Browser-targeted bundles with Node.js dependencies external
  - Brotli compression level 11
  - All modular exports independently measured

  Phase 6 (Advanced Media Processing) now complete:
  ✅ 6.1: Thumbnail Generation
  ✅ 6.2: Progressive Loading
  ✅ 6.3: FS5 Integration
  ✅ 6.4: Bundle Optimisation

  Updated IMPLEMENTATION.md to reflect Phase 6 completion.

Author: Developer

docs/BUNDLE_ANALYSIS.md

@@ -0,0 +1,140 @@
+# S5.js Bundle Analysis Report
+
+**Generated:** 2025-10-17T21:36:18.716Z
+
+## Executive Summary
+
+This report analyzes bundle sizes for different entry points of the S5.js library to ensure compliance with the grant requirement of ≤ 700KB compressed.
+
+## Bundle Sizes
+
+| Bundle | Raw | Gzip | Brotli | Status |
+|--------|-----|------|--------|--------|
+| Core | 214.72 KB | 71.75 KB | 59.61 KB | ✅ Pass |
+| Media | 35.98 KB | 11.03 KB | 9.79 KB | ✅ Pass |
+| Full | 217.15 KB | 72.37 KB | 60.09 KB | ✅ Pass |
+
+## Tree-Shaking Analysis
+
+The modular export structure enables consumers to import only what they need:
+
+- **Core only:** 59.61 KB (excludes media processing)
+- **Media only:** 9.79 KB (media processing modules)
+- **Full bundle:** 60.09 KB (all features)
+- **Combined (Core + Media):** 69.41 KB
+- **Shared code savings:** 9.31 KB (13.4% efficiency)
+
+## Detailed Breakdown
+
+### Core
+
+**Description:** File system operations without media processing
+
+**Entry Point:** `dist/src/exports/core.js`
+
+**Sizes:**
+- Raw: 214.72 KB
+- Gzipped: 71.75 KB (33.4% of raw)
+- Brotli: 59.61 KB (27.8% of raw)
+
+**Metadata:**
+- Input files: 295
+- Output modules: 1
+
+### Media
+
+**Description:** Media processing modules only
+
+**Entry Point:** `dist/src/exports/media.js`
+
+**Sizes:**
+- Raw: 35.98 KB
+- Gzipped: 11.03 KB (30.7% of raw)
+- Brotli: 9.79 KB (27.2% of raw)
+
+**Metadata:**
+- Input files: 9
+- Output modules: 1
+
+### Full
+
+**Description:** Complete SDK with all features
+
+**Entry Point:** `dist/src/index.js`
+
+**Sizes:**
+- Raw: 217.15 KB
+- Gzipped: 72.37 KB (33.3% of raw)
+- Brotli: 60.09 KB (27.7% of raw)
+
+**Metadata:**
+- Input files: 295
+- Output modules: 1
+
+## Recommendations
+
+✅ **Full bundle size is within the 700KB limit** (60.09 KB)
+
+### For Application Developers:
+
+1. **Use modular imports** to reduce bundle size:
+   ```javascript
+   // Import only what you need
+   import { S5, FS5 } from 's5/core';  // Smaller bundle
+   import { MediaProcessor } from 's5/media';  // Add media when needed
+   ```
+
+2. **Lazy-load media processing** for optimal initial load:
+   ```javascript
+   // Media modules use dynamic imports internally
+   const media = await import('s5/media');
+   await media.MediaProcessor.initialize();
+   ```
+
+3. **Tree-shaking is enabled** - modern bundlers will eliminate unused code automatically.
+
+## Grant Compliance
+
+**Requirement:** Bundle size ≤ 700KB compressed (brotli)
+
+**Status:** ✅ **COMPLIANT**
+
+- Full bundle (brotli): 60.09 KB
+- Target: 700 KB
+- Margin: 639.91 KB under budget
+
+## Technical Implementation
+
+### Code Splitting
+
+The library uses a modular export structure with separate entry points:
+
+1. **Main export** (`s5`): Full SDK with all features
+2. **Core export** (`s5/core`): File system operations only
+3. **Media export** (`s5/media`): Media processing with lazy loading
+
+### Lazy Loading
+
+Media processing modules use dynamic imports to enable code splitting:
+
+- `MediaProcessorLazy` loads the actual implementation on first use
+- WASM modules are loaded only when needed
+- Canvas fallback loads separately from WASM
+
+### Tree-Shaking
+
+- Package.json includes `"sideEffects": false`
+- ES modules with proper export structure
+- Modern bundlers can eliminate unused code
+
+### Build Configuration
+
+- **Target:** ES2022
+- **Format:** ESM (ES modules)
+- **Minification:** Enabled
+- **Source maps:** Available for debugging
+- **TypeScript:** Declarations generated
+
+---
+
+*This report was automatically generated by `scripts/analyze-bundle.js`*

docs/IMPLEMENTATION.md

@@ -326,11 +326,11 @@
   - [x] Create comprehensive unit test suite (29 tests passing)
   - [x] Create integration test suite (skipped pending IndexedDB)
   - [x] Update API documentation with media extensions
-- [ ] **6.4 Bundle Optimisation**
-  - [ ] Configure webpack for code splitting
-  - [ ] Implement WASM lazy loading
-  - [ ] Verify bundle size ≤ 700KB compressed
-  - [ ] Create bundle analysis report
+- [x] **6.4 Bundle Optimisation** ✅ COMPLETE (2025-10-17)
+  - [x] Configure esbuild for bundle analysis (using modular exports instead of webpack)
+  - [x] Implement WASM lazy loading (via dynamic imports in index.lazy.ts)
+  - [x] Verify bundle size ≤ 700KB compressed (60.09 KB brotli - 10x under limit!) ✅
+  - [x] Create bundle analysis report (docs/BUNDLE_ANALYSIS.md, bundle-analysis.json)
 
 ### Phase 7: Testing & Performance (Grant Month 7)
 
@@ -375,7 +375,7 @@
 - [x] All new code has tests ✅
 - [x] TypeScript strict mode compliance ✅
 - [x] No linting errors ✅
-- [ ] Bundle size within limits (pending Phase 5)
+- [x] Bundle size within limits (60.09 KB brotli - far under 700 KB target) ✅
 - [x] Performance benchmarks pass ✅
 - [x] Documentation complete ✅
 - [ ] Cross-browser compatibility verified (pending Phase 5)
@@ -390,10 +390,12 @@
 4. **Phase 4**: Utility Functions (DirectoryWalker, BatchOperations) ✅
 5. **Phase 4.5**: Real S5 Portal Integration ✅
 6. **Phase 4.6**: Documentation & Export Updates ✅
-7. **Phase 5**: Media Processing Foundation (Complete) ✅
-8. **Phase 6.1**: Thumbnail Generation ✅
-9. **Phase 6.2**: Progressive Loading ✅
-10. **Phase 6.3**: FS5 Integration ✅
+7. **Phase 5**: Media Processing Foundation ✅
+8. **Phase 6**: Advanced Media Processing ✅
+   - **6.1**: Thumbnail Generation ✅
+   - **6.2**: Progressive Loading ✅
+   - **6.3**: FS5 Integration ✅
+   - **6.4**: Bundle Optimisation ✅
 
 ### Phase 5 Status (Media Processing)
 
@@ -404,12 +406,13 @@
 - ✅ **5.4**: Browser Compatibility (full capability detection & strategy selection)
 - ✅ **5.5**: Production Readiness (real WASM implementation complete)
 
-### Phase 6 Status (Advanced Media Processing)
+### Phase 6 Status (Advanced Media Processing) ✅ COMPLETE
 
 **Completed Sub-phases:**
 - ✅ **6.1**: Thumbnail Generation (Canvas-based with smart cropping & size optimization)
 - ✅ **6.2**: Progressive Loading (JPEG/PNG/WebP multi-layer support)
 - ✅ **6.3**: FS5 Integration (putImage, getThumbnail, getImageMetadata, createImageGallery with path-based design)
+- ✅ **6.4**: Bundle Optimisation (esbuild analysis, modular exports, lazy loading - 60.09 KB compressed)
 
 ### Key Achievements
 
@@ -425,10 +428,30 @@
 - Comprehensive test suite (233 tests passing across 14 test files)
 - Full API documentation
 - Performance benchmarks documented
+- Bundle optimization complete with modular exports (60.09 KB compressed)
+- Lazy loading for media processing (9.79 KB media module)
+- Tree-shaking enabled with 13.4% efficiency
+
+### Bundle Size Results (Phase 6.4)
+
+**Grant Requirement:** ≤ 700 KB compressed (brotli)
+
+**Actual Results:**
+- **Full Bundle:** 60.09 KB (10.6x under limit) ✅
+- **Core Only:** 59.61 KB (file system operations)
+- **Media Only:** 9.79 KB (media processing)
+- **Margin:** 639.91 KB under budget
+
+**Implementation:**
+- Modular exports via package.json (`s5`, `s5/core`, `s5/media`)
+- Dynamic imports for lazy loading (`index.lazy.ts`)
+- Tree-shaking enabled (`sideEffects: false`)
+- Bundle analysis tool (`npm run analyze-bundle`)
+- Comprehensive report (docs/BUNDLE_ANALYSIS.md)
 
 ### Current Work
 
-**Phase 6.4**: Bundle Optimisation - Next phase focuses on webpack configuration, code splitting, and bundle size verification
+**Phase 6 Complete!** All advanced media processing features implemented with excellent bundle size performance.
 
 ## Notes
 

docs/bundle-analysis.json

@@ -0,0 +1,60 @@
+{
+  "timestamp": "2025-10-17T21:36:18.718Z",
+  "bundles": [
+    {
+      "name": "Core",
+      "description": "File system operations without media processing",
+      "entryPoint": "dist/src/exports/core.js",
+      "sizes": {
+        "raw": 219872,
+        "gzipped": 73475,
+        "brotli": 61044
+      },
+      "metadata": {
+        "inputs": 295,
+        "modules": 1
+      }
+    },
+    {
+      "name": "Media",
+      "description": "Media processing modules only",
+      "entryPoint": "dist/src/exports/media.js",
+      "sizes": {
+        "raw": 36840,
+        "gzipped": 11294,
+        "brotli": 10028
+      },
+      "metadata": {
+        "inputs": 9,
+        "modules": 1
+      }
+    },
+    {
+      "name": "Full",
+      "description": "Complete SDK with all features",
+      "entryPoint": "dist/src/index.js",
+      "sizes": {
+        "raw": 222363,
+        "gzipped": 74107,
+        "brotli": 61537
+      },
+      "metadata": {
+        "inputs": 295,
+        "modules": 1
+      }
+    }
+  ],
+  "treeShaking": {
+    "coreSize": 61044,
+    "mediaSize": 10028,
+    "fullSize": 61537,
+    "combined": 71072,
+    "savings": 9535,
+    "efficiency": 13.415972534894191
+  },
+  "compliance": {
+    "target": 716800,
+    "actual": 61537,
+    "status": true
+  }
+}