fix

apps/monitor/src/runner.rs

@@ -26,13 +26,20 @@ pub async fn fetch_and_run(
     in_flight: &Arc<Mutex<HashSet<String>>>,
 ) -> Result<usize> {
     let url = format!("{coordinator_url}/internal/due?region={region}&lookahead_ms=2000");
-    let monitors: Vec<Monitor> = client
+    let resp = client
         .get(&url)
         .header("x-monitor-token", token)
         .send()
-        .await?
-        .json()
         .await?;
+    let status = resp.status();
+    let body = resp.text().await?;
+    let monitors: Vec<Monitor> = match serde_json::from_str(&body) {
+        Ok(m) => m,
+        Err(e) => {
+            let preview: String = body.chars().take(500).collect();
+            anyhow::bail!("/internal/due returned status {status}, body could not be parsed: {e}. Body preview: {preview}");
+        }
+    };
 
     let n = monitors.len();
     if n == 0 { return Ok(0); }