//! Event variants that a running subagent can emit to its parent via the
//! shared mpsc channel.
use serde_json::Value;

/// Progress and outcome events emitted by `run_subagent` as it processes
/// LLM responses and tool calls.
#[derive(Debug, Clone)]
pub enum SubagentEvent {
    StepCompleted {
        output: String,
    },
    StepFailed {
        step: usize,
        error: String,
    },
    Completed,
    ToolCall {
        tool: String,
        args: Value,
    },
    ToolResult {
        tool: String,
        args: Value,
    },
    Progress(String),
    /// Token usage reported by the LLM after one streaming call inside the
    /// subagent. The drain thread accumulates these across all steps and
    /// forwards the total to the parent's `TurnEvent::ReviewUsage` handler
    /// so the Usage panel can split "main" tokens from "self-learning"
    /// tokens (review, test-gen, arch-review, security-review, etc.).
    ///
    /// Why a separate variant instead of folding into `Completed`: usage
    /// is reported per-step, so the parent can update the running total
    /// incrementally rather than waiting for the whole subagent run to
    /// finish. The drain thread still aggregates before forwarding.
    Usage {
        tokens_in: u64,
        tokens_out: u64,
    },
}