add prometheus metrics

src/bot_actions/review.rs

@@ -4,10 +4,7 @@ use tokio_util::io::StreamReader;
 use tracing::instrument;
 
 use crate::{
-    bot::ReviewResult,
-    consts::{BOT_PROCESS_MSG, MAX_DIFF_SIZE, REVIEW_PROMPT},
-    gitea::{GiteaAPI, ReviewPayload},
-    open_router::OpenRouterClient,
+    bot::ReviewResult, consts::{BOT_PROCESS_MSG, MAX_DIFF_SIZE, REVIEW_PROMPT}, gitea::{GiteaAPI, ReviewPayload}, metrics, open_router::OpenRouterClient,
 };
 
 #[instrument(skip(gitea_api, open_router_client, http_client, review_payload))]
@@ -48,6 +45,9 @@ pub async fn exec_review(
         let mut review_result = serde_json::from_str::<ReviewResult>(&chat_result.message)?;
 
         review_result.cost = chat_result.cost;
+        if let Some(cost) = review_result.cost {
+            metrics::openrouter_cost_usd((cost / 100.0).round() as u64);
+        }
 
         let final_review_markdown = review_result_to_markdown(&review_result);