refactor(#2359): bare Deserialize derive + clarify error to_string scan

hive-claude/src/classify.rs

@@ -54,7 +54,7 @@ const SESSION_NOT_FOUND_MARKERS: [&str; 2] = [
 /// so a field-shape drift is a compile error / a clean fallback rather than a
 /// silent mis-detection. Unknown event types fall into [`StreamEvent::Other`]
 /// (scanned raw like any other control event).
-#[derive(serde::Deserialize)]
+#[derive(Deserialize)]
 #[serde(tag = "type", rename_all = "snake_case")]
 enum StreamEvent {
     /// Model-authored turn output — never scanned (it can quote any marker).
@@ -77,7 +77,7 @@ enum StreamEvent {
 /// error signal — `is_error` is the discriminator (the CLI sets it from the
 /// real outcome; the model can't forge it). On `is_error` the `result` /
 /// `error` fields carry claude-code's own failure text.
-#[derive(serde::Deserialize)]
+#[derive(Deserialize)]
 struct ResultEvent {
     #[serde(default)]
     is_error: bool,
@@ -152,6 +152,10 @@ impl Sentinels {
                         self.scan_failure_markers(text);
                     }
                     if let Some(err) = &r.error {
+                        // `to_string()` re-serializes the JSON value (a string
+                        // value round-trips to `"...quoted..."`), but the marker
+                        // substring still appears inside the quoted form, so the
+                        // scan finds it either way.
                         self.scan_failure_markers(&err.to_string());
                     }
                     // Typed 401: an auth failure that set the status code but