fix: handle Map type in getChatUsage() after deserialization (#1118)

mvanhorn · web-flow · commit 9f9e69a45d0a · 2026-04-20T15:57:33.000+08:00
## Summary `getChatUsage()` returns null when `_chat_usage` metadata is a Map (after session persistence/reload) instead of a ChatUsage object. ## Why this matters When messages are persisted via `agent.loadFrom()` and reloaded, JSON deserialization converts the `_chat_usage` metadata value to a `Map<String, Object>` instead of a `ChatUsage` instance. The existing `instanceof ChatUsage` check fails, returning null even though the token usage data exists in the metadata. ## Changes `agentscope-core/src/main/java/io/agentscope/core/message/Msg.java`: - Added Map handling in `getChatUsage()` (line 413): when the metadata value is a Map, extract `inputTokens`, `outputTokens`, and `time` fields, build a ChatUsage via the builder, and cache it back in metadata for subsequent calls - Added `toInt()` and `toDouble()` helper methods for safe numeric conversion from deserialized values (handles Integer, Long, Double from JSON) ## Testing - When `_chat_usage` is a ChatUsage object: unchanged behavior - When `_chat_usage` is a Map (post-deserialization): converts to ChatUsage and returns it - When `_chat_usage` is null or absent: returns null (unchanged) - The converted ChatUsage is cached back in metadata so the conversion only happens once Fixes #1115 This contribution was developed with AI assistance (Claude Code). --------- Co-authored-by: Matt Van Horn <455140+mvanhorn@users.noreply.github.com>
diff --git a/agentscope-core/src/main/java/io/agentscope/core/message/Msg.java b/agentscope-core/src/main/java/io/agentscope/core/message/Msg.java
@@ -415,7 +415,36 @@ public ChatUsage getChatUsage() {
             return null;
         }
         Object usage = metadata.get(MessageMetadataKeys.CHAT_USAGE);
-        return usage instanceof ChatUsage ? (ChatUsage) usage : null;
+        if (usage instanceof ChatUsage) {
+            return (ChatUsage) usage;
+        }
+        if (usage instanceof Map) {
+            @SuppressWarnings("unchecked")
+            Map<String, Object> map = (Map<String, Object>) usage;
+            ChatUsage chatUsage =
+                    ChatUsage.builder()
+                            .inputTokens(toInt(map.get("inputTokens")))
+                            .outputTokens(toInt(map.get("outputTokens")))
+                            .time(toDouble(map.get("time")))
+                            .build();
+            metadata.put(MessageMetadataKeys.CHAT_USAGE, chatUsage);
+            return chatUsage;
+        }
+        return null;
+    }
+
+    private static int toInt(Object value) {
+        if (value instanceof Number) {
+            return ((Number) value).intValue();
+        }
+        return 0;
+    }
+
+    private static double toDouble(Object value) {
+        if (value instanceof Number) {
+            return ((Number) value).doubleValue();
+        }
+        return 0.0;
     }
 
     /**
