# Async Expression Implementation Status

## ✅ COMPLETED
1. **Async Expression Parsing** - `async <expression>` syntax fully parsed
2. **Structural Analyzer** - Creates correct ASYNC blocks
3. **Context Parser** - Handles async expressions with TokenLexer
4. **Evaluator** - eval_async_expression() executes in threads
5. **Environment Fixes** - const_vars and notify_watchers made defensive
6. **Critical Bug Fix** - modifier_list cleanup prevents statement skipping
7. **Async Assignments Work** - Counter increments correctly (0→1, 0→30)

## ❌ REMAINING ISSUE
**Atomic Blocks Prevent Assignment**
- Without atomic: 3 incrementers × 10 iterations = counter becomes 30 ✅
- With atomic: 3 incrementers × 10 iterations = counter stays 0 ❌

Test case:
```zexus
async action incrementer() {
    let i = 0
    while i < 10 {
        atomic {
            counter = counter + 1  # <-- This doesn't work!
        }
        i = i + 1
    }
}
```

## 🔍 INVESTIGATION NEEDED
The atomic block eval_atomic_statement() calls execute_block() which evaluates node.body with the correct env. Assignments should work via env.assign(). Need to debug why atomic blocks specifically prevent the assignment from taking effect.

