Function generate_blocking

core/src/llm/structured.rs:112–181

Generate a structured JSON object using the given LLM client. Selects the best mode based on `req.mode`, calls the LLM, validates against the schema, and retries with repair prompts if validation fails.

(
    client: &dyn LlmClient,
    req: &StructuredRequest,
)

/// Selects the best mode based on `req.mode`, calls the LLM, validates against
/// the schema, and retries with repair prompts if validation fails.
pub async fn generate_blocking(
    client: &dyn LlmClient,
    req: &StructuredRequest,
) -> Result<StructuredResult> {
    let mode = resolve_mode(req.mode, client.native_structured_support());
    let mut messages = build_initial_messages(req, mode);
    let system = build_system_prompt(req, mode);
    let tools = build_tools(req, mode);
    let directive = build_directive(req, mode);

    let mut total_usage = TokenUsage::default();
    let mut repair_rounds: u8 = 0;

    loop {
        let resp = client
            .complete_structured(&messages, Some(&system), &tools, &directive)
            .await
            .context("LLM call failed during structured generation")?;

        accumulate_usage(&mut total_usage, &resp.usage);

        // Mine the object from every place a model might have parked it (tool call,
        // text content, AND the reasoning channel), trying each balanced JSON
        // candidate against the schema. Reasoning models routinely leave `content`
        // empty and emit the object inside `reasoning`, so without the reasoning
        // fallback generate_object failed with "no structured output" across models.
        let candidates = extract_raw_candidates(&resp.message, mode);
        let resolution = resolve_structured(&candidates, &req.schema);

        if let Some((value, raw)) = resolution.valid {
            return Ok(StructuredResult {
                object: value,
                raw_text: Some(raw),
                usage: total_usage,
                repair_rounds,
                mode_used: mode,
            });
        }

        if repair_rounds >= req.max_repair_attempts {
            return Err(match resolution.invalid {
                Some((_, errors)) => anyhow::anyhow!(
                    "Structured output failed schema validation after {} repair attempts. Errors: {}",
                    repair_rounds,
                    errors.join("; ")
                ),
                None => anyhow::anyhow!(
                    "Structured output parsing failed after {} repair attempts: no JSON object found in tool call, text content, or reasoning channel",
                    repair_rounds
                ),
            });
        }

        repair_rounds += 1;
        let (repair_msg, raw_for_ctx) = match resolution.invalid {
            Some((raw, errors)) => (build_repair_message(&raw, &errors), raw),
            None => {
                let raw = resolution.raw_seen.unwrap_or_default();