schema-coerce

Coerce an LLM-emitted JSON value to a small field-schema.

LLMs return "42" instead of 42, "true" instead of true, or wrap the answer in { "result": {...} }. This crate gives you a lossy coerce(value, &schema) that applies the obvious fixes:

• String containing an integer → integer
• String containing a float → float
• String "true" / "false" / "yes" / "no" → bool
• Object containing a single key whose value matches the schema → unwrap (handles wrappers like { "result": {...} })
• Missing field → fill from default

Example

use schema_coerce::{coerce, Field, Type};
use serde_json::json;

let schema = vec![
    Field { name: "count", ty: Type::Int, default: None },
    Field { name: "ok", ty: Type::Bool, default: Some(json!(false)) },
];
let raw = json!({ "count": "42", "ok": "yes" });
let fixed = coerce(raw, &schema);
assert_eq!(fixed["count"], json!(42));
assert_eq!(fixed["ok"], json!(true));

schema-coerce

Coerce LLM JSON values to a simple field-schema. String→int, "yes"→ true, unwrap {"result": {...}} wrappers, fill missing fields from defaults.

use schema_coerce::{coerce, Field, Type};
use serde_json::json;

let schema = vec![
    Field { name: "count", ty: Type::Int, default: None },
    Field { name: "ok", ty: Type::Bool, default: Some(json!(false)) },
];
let raw = json!({ "count": "42", "ok": "yes" });
let fixed = coerce(raw, &schema);
assert_eq!(fixed["count"], json!(42));

Pair with llm-json-repair (parse) and json-pluck (extract). MIT or Apache-2.0.