Function extract_json_value

core/src/llm/structured.rs:299–333

Extract a JSON value from potentially dirty LLM output. Handles: raw JSON, markdown code fences, leading/trailing prose.

(text: &str)

///
/// Handles: raw JSON, markdown code fences, leading/trailing prose.
pub fn extract_json_value(text: &str) -> Result<Value> {
    let trimmed = text.trim();

    // 1. Direct parse
    if let Ok(v) = serde_json::from_str::<Value>(trimmed) {
        if v.is_object() || v.is_array() {
            return Ok(v);
        }
    }

    // 2. Strip markdown code fence
    if let Some(inner) = strip_code_fence(trimmed) {
        if let Ok(v) = serde_json::from_str::<Value>(inner.trim()) {
            if v.is_object() || v.is_array() {
                return Ok(v);
            }
        }
    }

    // 3. Find balanced JSON substring (first { to matching })
    if let Some(candidate) = find_balanced_json_object(trimmed) {
        if let Ok(v) = serde_json::from_str::<Value>(candidate) {
            return Ok(v);
        }
    }

    // 4. Try array
    if let Some(candidate) = find_balanced_json_array(trimmed) {
        if let Ok(v) = serde_json::from_str::<Value>(candidate) {
            return Ok(v);
        }
    }

    bail!("No valid JSON object found in LLM output")
}

/// Strip ```json ... ``` or ``` ... ``` fences.
fn strip_code_fence(text: &str) -> Option<&str> {