## String Diff

**Path:** `src/string-diff.ts`  
**Export:** `calculateStringDiff`, `applyStringDiff`, `calculateDiffSavings`, `shouldUseDiff`, `StringDiff`

### What it does

Efficiently encodes string changes by finding common prefix and suffix, only encoding the differing middle section.

### Key API

| Function | Description |
|----------|-------------|
| `calculateStringDiff(previous, current)` | Compute `{ prefixLen, suffixLen, middleLen, middle }` |
| `applyStringDiff(previous, diff)` | Reconstruct current string from diff |
| `calculateDiffSavings(previous, current, diff)` | Percentage savings from diff encoding |
| `shouldUseDiff(previous, current, threshold?)` | Decide whether diff encoding is worthwhile |

### Format

`[prefixLen][suffixLen][middleLen][middleChars...]` — each length field is 1 byte.

### Used by

- Delta compression for string fields in game state
- Network protocols with repetitive string data