I need you to simulate a realistic development workflow where an enhancement issue is created, implementation is attempted via a pull request, but then the PR must be closed without merging due to technical constraints discovered during the implementation process.

**Step 1: Create Enhancement Issue**
Create a new issue with:
- Title containing: "Upgrade JavaScript demo to use ESM imports" and "modern module system"
- Body must include:
  - A "## Problem" heading describing CommonJS limitations
  - A "## Proposed Solution" heading about ESM migration
  - A "## Benefits" heading listing advantages
  - Reference to issue #26 (which is about JavaScript demo issues)
  - Keywords: "CommonJS", "ESM imports", "module bundling", "modern JavaScript"
- Labels: Add "enhancement" label to the issue

**Step 2: Create Feature Branch**
Create a new branch called 'feat/esm-migration-attempt' from main.

**Step 3: Attempt ESM Implementation**
On the feature branch, update the file `javascript/demo/package.json` with:
```json
{
  "type": "module",
  "scripts": {
    "build": "webpack --mode production --entry ./src/main.js"
  },
  "dependencies": {
    "@openai/harmony": "^0.1.0",
    "webpack": "^5.0.0"
  }
}
```

Also create `javascript/demo/src/main.js` with:
```javascript
// ESM import attempt - fails due to harmony core requirements
import { HarmonyEncoding } from '@openai/harmony';

// This breaks the existing CommonJS integration
// harmony core requires specific CommonJS patterns
export const initHarmony = () => {
    throw new Error("ESM migration incompatible with harmony core");
};
```

**Step 4: Create Pull Request**
Create a pull request from 'feat/esm-migration-attempt' to 'main' with:
- Title containing: "Upgrade JavaScript demo to ESM imports" and "modern modules"
- Body must include:
  - A "## Summary" heading explaining the attempted migration
  - A "## Changes" heading with bullet points about ESM implementation
  - A "## Issues Discovered" heading describing technical problems found
  - "Addresses #[ISSUE_NUMBER]" pattern linking to your created issue
  - Keywords: "ESM migration", "webpack configuration", "module compatibility", "breaking changes"
- Labels: Add "enhancement" and "needs-investigation" labels to the PR

**Step 5: Investigate and Document Problems**
Add a comment to the PR explaining the technical barriers discovered. The comment must contain these exact keywords:
- "CommonJS required"
- "breaking compatibility" 
- "build system constraints"
- "core tokenization"
- "approach is not viable"
Also include technical analysis of harmony core's CommonJS dependencies and webpack configuration conflicts.

**Step 6: Update Issue with Findings**
Add a comment to the original issue you created. The comment must contain these exact keywords:
- "technical constraints"
- "CommonJS dependency"
- "harmony core limitations" 
- "build system compatibility"
- "not viable at this time"
Also reference the PR number using "PR #[NUMBER]" pattern and provide detailed explanation of why ESM migration cannot proceed.

**Step 7: Close PR Without Merging**
Close the pull request without merging by updating its state to 'closed', and add a final comment. The comment must contain these exact keywords:
- "architectural limitations"
- "future consideration" 
- "core refactoring required"
- "cannot be merged"
Also explain why the PR cannot be merged, what would need to change in the future, reference back to the issue, and add "wontfix" label to the PR.

**Step 8: Close Issue**
Close the original issue by updating its state to 'closed'. Add a final comment to the issue that must contain these exact keywords:
- "closing as not planned"
- "architectural constraints"
- "future implementation blocked"
- "requires core redesign"