JSON to Rust Struct Converter

From a JSON sample to a Rust struct

The struct derives Serialize and Deserialize, with a #[serde(rename = "...")] on each field mapping the snake_case Rust name back to the original key. Serde generates the implementation at compile time, so nothing here costs anything at runtime beyond the parse itself.

Tightening the generated struct

• Collapse the renames. If every key differs from the Rust name only by case, a single #[serde(rename_all = "camelCase")] on the struct replaces every per-field attribute.
• Optional fields. Option<T> covers an explicit null, and adding #[serde(default)] also covers a key that is absent entirely. Without default, a missing key is a deserialisation error rather than a None.
• Integer width. Numbers infer as i64 and f64. Narrow to u32 or u16 when the API documents a range, remembering that serde rejects a negative value for an unsigned type rather than wrapping it.
• Ownership. Fields come out as owned String. Borrowing with &str avoids the allocation but ties the struct to the lifetime of the input buffer, which pays off only when you parse a great deal and discard it quickly.
• A JSON null with nothing else to go on infers as a placeholder option type rather than an answer. Replace it once you know the real type.

The same payload for other backends: JSON to Go and JSON to TypeScript.