JSON Merge

The JSON merge patcher performs a deep merge of two objects using defu. xtarterize uses it whenever it updates JSON configuration such as tsconfig.json, biome.json, or VS Code settings.

Merge behavior

• Existing keys take precedence; incoming values only fill gaps.
• Nested objects merge recursively.
• Arrays are replaced entirely, not concatenated. Tasks that need to combine arrays use a custom merge.

Writing to files

Object merging alone would discard comments and formatting, so file writes use a second patcher that edits the JSON text directly. It preserves:

• Comments
• Key order
• Whitespace and indentation
• Trailing commas in JSONC

JSON merge targets combine both steps: the object merge computes the target state, then the text patch applies it to the original file.

See the patchers overview for how the patchers fit together.