Preserve informational flags in dashboard usage windows (VibeTV #306)

rust/src/cli/serve/dashboard/window.rs

@@ -10,6 +10,9 @@ pub struct WindowPayload {
     pub used_percent: f64,
     pub remaining_percent: f64,
     pub reset_at: Option<chrono::DateTime<chrono::Utc>>,
+    /// Preserve the engine's measurement validity for provider and account clients.
+    #[serde(skip_serializing_if = "is_false")]
+    pub is_informational: bool,
     /// Display-only hint. Script clients can ignore this additive schema-v1 key.
     #[serde(skip_serializing_if = "is_false")]
     pub idle: bool,
@@ -23,6 +26,36 @@ fn is_false(value: &bool) -> bool {
     !*value
 }
 
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn informational_window_keeps_its_authoritative_flag() {
+        let payload = make_window_with_idle(
+            "session",
+            "Session",
+            &RateWindow::no_active_session(),
+            false,
+        );
+        let json = serde_json::to_value(payload).unwrap();
+        assert_eq!(json["isInformational"], true);
+        assert_eq!(json["usedPercent"], 0.0);
+        assert!(json["resetAt"].is_null());
+    }
+
+    #[test]
+    fn measured_zero_without_reset_is_not_informational() {
+        for kind in ["session", "weekly"] {
+            let payload = make_window_with_idle(kind, kind, &RateWindow::new(0.0), false);
+            let json = serde_json::to_value(payload).unwrap();
+            assert!(json.get("isInformational").is_none());
+            assert_eq!(json["usedPercent"], 0.0);
+            assert!(json["resetAt"].is_null());
+        }
+    }
+}
+
 pub(super) fn make_window_with_idle(
     kind: &str,
     label: &str,
@@ -36,6 +69,7 @@ pub(super) fn make_window_with_idle(
         used_percent: used,
         remaining_percent: (100.0 - used).clamp(0.0, 100.0),
         reset_at: window.resets_at,
+        is_informational: window.is_informational,
         idle,
         unavailable: window.is_informational,
     }