fix: parse gemini cli usage metadata variants

internal/runtime/executor/helps/usage_helpers.go

@@ -370,12 +370,22 @@ func parseGeminiFamilyUsageDetail(node gjson.Result) usage.Detail {
 	return detail
 }
 
+func hasGeminiFamilyUsageTokenFields(node gjson.Result) bool {
+	return node.Get("promptTokenCount").Exists() ||
+		node.Get("candidatesTokenCount").Exists() ||
+		node.Get("thoughtsTokenCount").Exists() ||
+		node.Get("totalTokenCount").Exists() ||
+		node.Get("cachedContentTokenCount").Exists()
+}
+
 func ParseGeminiCLIUsage(data []byte) usage.Detail {
 	usageNode := gjson.ParseBytes(data)
-	node := usageNode.Get("response.usageMetadata")
-	if !node.Exists() {
-		node = usageNode.Get("response.usage_metadata")
-	}
+	node := firstExistingUsageNode(usageNode,
+		"response.usageMetadata",
+		"response.usage_metadata",
+		"usageMetadata",
+		"usage_metadata",
+	)
 	if !node.Exists() {
 		return usage.Detail{}
 	}
@@ -414,16 +424,32 @@ func ParseGeminiCLIStreamUsage(line []byte) (usage.Detail, bool) {
 	if len(payload) == 0 || !gjson.ValidBytes(payload) {
 		return usage.Detail{}, false
 	}
-	node := gjson.GetBytes(payload, "response.usageMetadata")
-	if !node.Exists() {
-		node = gjson.GetBytes(payload, "usage_metadata")
-	}
+	root := gjson.ParseBytes(payload)
+	node := firstExistingUsageNode(root,
+		"response.usageMetadata",
+		"response.usage_metadata",
+		"usageMetadata",
+		"usage_metadata",
+	)
 	if !node.Exists() {
 		return usage.Detail{}, false
 	}
+	if !hasGeminiFamilyUsageTokenFields(node) {
+		return usage.Detail{}, false
+	}
 	return parseGeminiFamilyUsageDetail(node), true
 }
 
+func firstExistingUsageNode(root gjson.Result, paths ...string) gjson.Result {
+	for _, path := range paths {
+		node := root.Get(path)
+		if node.Exists() {
+			return node
+		}
+	}
+	return gjson.Result{}
+}
+
 func ParseAntigravityUsage(data []byte) usage.Detail {
 	usageNode := gjson.ParseBytes(data)
 	node := usageNode.Get("response.usageMetadata")