Adjust Claude prefill merge handling and remove BOM

modules/streaming-generation.js

@@ -136,16 +136,11 @@ class StreamingGeneration {
             const opts = { ...baseOptions, ...this.resolveCurrentApiAndModel(baseOptions) };
 
             const modelLower = String(opts.model || '').toLowerCase();
-            const isClaudeThinkingModel = 
-                modelLower.includes('claude') && 
-                modelLower.includes('thinking') && 
-                !modelLower.includes('nothinking');
+            const isClaudeModel = modelLower.includes('claude');
 
-            if (isClaudeThinkingModel && Array.isArray(messages) && messages.length > 0) {
-                const lastMsg = messages[messages.length - 1];
-                if (lastMsg?.role === 'assistant') {
-                    console.log('[xbgen] Claude Thinking 模型：移除 assistant prefill');
-                    messages.pop();
+            if (isClaudeModel && Array.isArray(messages) && messages.length > 0) {
+                if (this._mergeAssistantPrefillIntoPrevious(messages)) {
+                    console.log('[xbgen] Claude model: merged trailing assistant prefill into previous message');
                 }
             }
 
@@ -805,6 +800,32 @@ class StreamingGeneration {
         return '';
     }
 
+    _mergeAssistantPrefillIntoPrevious(messages) {
+        if (!Array.isArray(messages) || messages.length < 2) return false;
+        const lastMsg = messages[messages.length - 1];
+        if (lastMsg?.role !== 'assistant') return false;
+
+        const assistantText = this._extractTextFromMessage(lastMsg).trim();
+        const previousMsg = messages[messages.length - 2];
+        if (!previousMsg) return false;
+
+        if (assistantText) {
+            const mergedText = `assistant:\n${assistantText}`;
+            if (typeof previousMsg.content === 'string') {
+                previousMsg.content = previousMsg.content
+                    ? `${previousMsg.content}\n\n${mergedText}`
+                    : mergedText;
+            } else if (Array.isArray(previousMsg.content)) {
+                previousMsg.content.push({ type: 'text', text: `\n\n${mergedText}` });
+            } else {
+                previousMsg.content = mergedText;
+            }
+        }
+
+        messages.pop();
+        return true;
+    }
+
     _getLastMessagesSnapshot() {
         const ctx = getContext();
         const list = Array.isArray(ctx?.chat) ? ctx.chat : [];
@@ -1494,3 +1515,4 @@ if (typeof window !== 'undefined') {
         eventSource: (window)?.eventSource || eventSource
     });
 }
+