# Tree-Shaking Phase 1 Summary

**Date**: 2025-01-20
**Status**: ✅ **Phase 1 Complete** - Validation and Analysis

---

## Phase 1 Objectives

1. ✅ Build all preset bundles using existing configs
2. ✅ Measure actual bundle sizes and compare to guide estimates
3. ⏸️ Test preset bundles in browser (deferred - bundles work but don't provide size benefits)
4. ✅ Update guide with actual measured sizes

---

## Key Findings

### Bundle Sizes - Actual vs Expected

| Bundle Type  | Actual Size | Actual (gzipped) | Expected (gzipped) | Gap              |
| ------------ | ----------- | ---------------- | ------------------ | ---------------- |
| **Full**     | 511 KB      | 112 KB           | ~130 KB            | ✅ -14% (better) |
| **Standard** | 447 KB      | 100 KB           | ~70 KB             | ❌ +43% (worse)  |
| **Minimal**  | 447 KB      | 100 KB           | ~60 KB             | ❌ +67% (worse)  |

### Critical Discovery

**Minimal and standard bundles are nearly identical** (both 447KB), achieving only **12% size reduction** vs full bundle instead of expected 60-70%.

### Root Cause Identified

**Static imports in `runtime.ts` prevent tree-shaking:**

```typescript
// packages/core/src/runtime/runtime.ts (lines 17-68)
import { createHideCommand } from '../commands/dom/hide';
import { createShowCommand } from '../commands/dom/show';
import { createToggleCommand } from '../commands/dom/toggle';
import { createAddCommand } from '../commands/dom/add';
import { createRemoveCommand } from '../commands/dom/remove';
// ... 20+ more command imports
```

**Why this breaks tree-shaking:**

1. Browser bundle imports `Runtime` class
2. Runtime imports ALL commands at module level
3. Rollup includes all transitive imports
4. Result: All commands bundled regardless of runtime configuration

**Key Insight**: `lazyLoad` option controls _runtime_ behavior (when commands are registered), not _bundle_ behavior (what code is included).

---

## Documents Created

### 1. TREE_SHAKING_ANALYSIS.md

Comprehensive technical analysis including:

- Root cause investigation
- Verification steps
- Three solution approaches with pros/cons
- Implementation recommendations
- Expected results after fix

### 2. Updated TREE_SHAKING_GUIDE.md

Added prominent warnings:

- ⚠️ Current limitations section at top
- Realistic size expectations
- Reference to analysis document
- Status updated to reflect current state
- Markdown linting issues fixed

---

## Solutions Identified

### Solution 1: Separate Runtime Classes ⭐ **Recommended**

Create dedicated runtime classes without static command imports:

**Structure:**

```
src/runtime/
  ├── runtime-base.ts      # Core runtime (no commands)
  ├── minimal-runtime.ts   # Only 8 commands
  ├── standard-runtime.ts  # Only 20 commands
  └── full-runtime.ts      # All commands (current Runtime)
```

**Benefits:**

- ✅ True tree-shaking (only imports needed commands)
- ✅ Clean separation of concerns
- ✅ Can achieve 60-70% size reduction
- ✅ Maintains current API

**Effort**: Medium (requires refactoring Runtime class)

### Solution 2: Dynamic Imports

Use `import()` for lazy command loading at runtime.

**Benefits:**

- ✅ True code-splitting
- ✅ Smallest initial bundle
- ✅ Works with existing architecture

**Drawbacks:**

- ⚠️ Async complexity
- ⚠️ First-use loading delay
- ⚠️ Requires network requests

**Effort**: Low-Medium

### Solution 3: Factory Functions

Create standalone factory functions per preset.

**Benefits:**

- ✅ True tree-shaking
- ✅ No Runtime refactoring

**Drawbacks:**

- ⚠️ Duplicates runtime logic
- ⚠️ Harder to maintain

**Effort**: Low

---

## Phase 1 Deliverables

### ✅ Completed

1. Built minimal preset bundle (447KB, 100KB gzipped)
2. Built standard preset bundle (447KB, 100KB gzipped)
3. Measured and documented actual sizes
4. Identified root cause of tree-shaking failure
5. Created comprehensive analysis document
6. Updated guide with realistic expectations
7. Documented three solution approaches

### ⏸️ Deferred

1. Browser testing of preset bundles - Not needed until bundles provide actual size benefits
2. Creation of preset factory functions - Will do as part of chosen solution

---

## Recommendations for Next Steps

### Immediate (Phase 2)

**Option A**: Implement Solution 1 (Separate Runtime Classes)

- Extract RuntimeBase from Runtime
- Create MinimalRuntime with 8 command imports
- Create StandardRuntime with 20 command imports
- Update browser bundle entry points
- Verify bundle sizes achieve expected reductions

**Option B**: Implement Solution 2 (Dynamic Imports)

- Add dynamic import support to EnhancedCommandRegistry
- Update lazyLoad implementation to use `import()`
- Test async loading behavior
- Verify bundle sizes and code-splitting

### Future (Phase 3+)

1. Create preset factory functions (as documented in guide)
2. Add granular package.json exports
3. Create smart build tool for HTML scanning
4. Develop Vite plugin for auto-detection
5. Publish optimized CDN bundles

---

## Success Criteria (Post-Fix)

After implementing chosen solution, validate:

- ✅ Minimal bundle ≤ 180KB (≤ 60KB gzipped) - **60% reduction from full**
- ✅ Standard bundle ≤ 280KB (≤ 80KB gzipped) - **29% reduction from full**
- ✅ Full bundle remains ~511KB (~112KB gzipped)
- ✅ All bundles function correctly in browser
- ✅ Documentation reflects actual sizes
- ✅ Tree-shaking verified with bundle analyzer

---

## Technical Debt Identified

1. **Runtime class is too monolithic** - Couples core runtime with all command implementations
2. **Lazy loading conflates two concepts** - Runtime registration vs bundle optimization
3. **No verification tooling** - No automated bundle size checks or regression detection
4. **Documentation was aspirational** - Guide documented desired state, not actual state

---

## Lessons Learned

1. **Static imports defeat tree-shaking** - Module-level imports are always bundled
2. **Runtime behavior ≠ Bundle optimization** - Need separation of concerns
3. **Measure, don't assume** - Guide estimates were off by 40-67%
4. **Documentation must reflect reality** - Aspirational docs mislead users

---

## Conclusion

Phase 1 successfully identified why tree-shaking isn't working as expected. The architecture _supports_ tree-shaking (modular exports, ES modules), but the implementation _prevents_ it (static imports in Runtime class).

**The good news**: We have clear solutions and a path forward. The modular command architecture is solid - we just need to refactor how Runtime imports commands.

**Recommendation**: Proceed with **Solution 1 (Separate Runtime Classes)** for best balance of correctness, maintainability, and performance.

---

## Artifacts

- ✅ [TREE_SHAKING_ANALYSIS.md](./TREE_SHAKING_ANALYSIS.md) - Technical analysis
- ✅ [TREE_SHAKING_GUIDE.md](./TREE_SHAKING_GUIDE.md) - Updated user guide
- ✅ [TREE_SHAKING_PHASE1_SUMMARY.md](./TREE_SHAKING_PHASE1_SUMMARY.md) - This document
- ✅ Built bundles in `dist/lokascript-browser-*.js`
- ✅ Bundle size measurements documented
