✨ Report actual graph memory from the buffer manager

graph-data gains bm-bytes (CALL bm_info() -> [mem_limit mem_usage], nil-safe, under the session lock); the session panel shows it as MiB behind the node/edge counts — real resident memory replacing the removed estimate.

Signed-off-by: Álvaro Tejero Cantero <alvorithm@teje.ro>

backend/resources/app/templates/graph-console.tmpl

@@ -1074,8 +1074,12 @@ Graph Console
         // shows per-table counts.
         const sizeEl = document.getElementById("graph-size");
         if (sizeEl) {
+          // bm-bytes = the session DB's buffer-manager usage (CALL
+          // bm_info()), i.e. actual resident memory, not an estimate.
+          const bm = data["bm-bytes"];
           sizeEl.textContent = data.nodes.length + " nodes, "
-            + data.edges.length + " edges";
+            + data.edges.length + " edges"
+            + (bm ? " (" + (bm / 1048576).toFixed(1) + " MiB)" : "");
           const counts = {};
           data.nodes.forEach(function (n) {
             counts[n.table] = (counts[n.table] || 0) + 1;

backend/src/app/graph/debug.clj

@@ -255,6 +255,14 @@
                   (:rows inst))
      :truncated? (boolean (or (:truncated? child) (:truncated? inst)))}))
 
+(defn- bm-usage-bytes
+  "Buffer-manager memory in use by this session's in-memory database
+  (`CALL bm_info()` → [mem_limit mem_usage]); nil if the call fails."
+  [conn]
+  (ex/ignoring
+   (-> (ladybug/query-on-connection! conn "CALL bm_info() RETURN *;" :max-rows 1)
+       :rows first second)))
+
 (defn export-graph-data!
   "Export the node/edge inventory of the in-memory graph for `profile-id`
   as plain data for the debug graph view. Returns nil when no session is
@@ -268,6 +276,7 @@
         {:file-id   (str file-id)
          :revn      (:revn index)
          :truncated (boolean (or nodes-truncated? edges-truncated?))
+         :bm-bytes  (bm-usage-bytes conn)
          :nodes     nodes
          :edges     edges}))))