diff --git a/src/graph.rs b/src/graph.rs
index 6428d3f..62dc986 100644
--- a/src/graph.rs
+++ b/src/graph.rs
@@ -504,7 +504,7 @@ fn label_propagation(
 /// A snapshot of graph topology metrics, for tracking evolution over time
 #[derive(Clone, Debug, Serialize, Deserialize)]
 pub struct MetricsSnapshot {
-    pub timestamp: f64,
+    pub timestamp: i64,
     pub date: String,
     pub nodes: usize,
     pub edges: usize,
@@ -548,14 +548,39 @@ pub fn save_metrics_snapshot(snap: &MetricsSnapshot) {
     }
 }
 
-/// Health report: summary of graph metrics
+/// Compute current graph metrics as a snapshot (no side effects).
+pub fn current_metrics(graph: &Graph) -> MetricsSnapshot {
+    let now = crate::store::now_epoch();
+    let date = crate::store::format_datetime_space(now);
+    MetricsSnapshot {
+        timestamp: now,
+        date,
+        nodes: graph.nodes().len(),
+        edges: graph.edge_count(),
+        communities: graph.community_count(),
+        sigma: graph.small_world_sigma(),
+        alpha: graph.degree_power_law_exponent(),
+        gini: graph.degree_gini(),
+        avg_cc: graph.avg_clustering_coefficient(),
+        avg_path_length: graph.avg_path_length(),
+    }
+}
+
+/// Health report: summary of graph metrics.
+/// Saves a metrics snapshot as a side effect (callers who want pure
+/// computation should use `current_metrics` + `save_metrics_snapshot`).
 pub fn health_report(graph: &Graph, store: &Store) -> String {
-    let n = graph.nodes().len();
-    let e = graph.edge_count();
-    let avg_cc = graph.avg_clustering_coefficient();
-    let avg_pl = graph.avg_path_length();
-    let sigma = graph.small_world_sigma();
-    let communities = graph.community_count();
+    let snap = current_metrics(graph);
+    save_metrics_snapshot(&snap);
+
+    let n = snap.nodes;
+    let e = snap.edges;
+    let avg_cc = snap.avg_cc;
+    let avg_pl = snap.avg_path_length;
+    let sigma = snap.sigma;
+    let alpha = snap.alpha;
+    let gini = snap.gini;
+    let communities = snap.communities;
 
     // Community sizes
     let mut comm_sizes: HashMap<u32, usize> = HashMap::new();
@@ -576,10 +601,6 @@ pub fn health_report(graph: &Graph, store: &Store) -> String {
         degrees.iter().sum::<usize>() as f64 / n as f64
     };
 
-    // Topology metrics
-    let alpha = graph.degree_power_law_exponent();
-    let gini = graph.degree_gini();
-
     // Low-CC nodes: poorly integrated
     let low_cc = graph.nodes().iter()
         .filter(|k| graph.clustering_coefficient(k) < 0.1)
@@ -588,18 +609,6 @@ pub fn health_report(graph: &Graph, store: &Store) -> String {
     // Category breakdown
     let cats = store.category_counts();
 
-    // Snapshot current metrics and log
-    let now = crate::store::now_epoch();
-    let date = crate::store::format_datetime_space(now);
-    let snap = MetricsSnapshot {
-        timestamp: now,
-        date: date.clone(),
-        nodes: n, edges: e, communities,
-        sigma, alpha, gini, avg_cc,
-        avg_path_length: avg_pl,
-    };
-    save_metrics_snapshot(&snap);
-
     // Load history for deltas
     let history = load_metrics_history();
     let prev = if history.len() >= 2 {