refactor: implement robust think tag stripping and CDATA handling for SSE stream parsing

internal/js/chat-stream/sse_parse_impl.js

@@ -7,6 +7,53 @@ const {
   SKIP_EXACT_PATHS,
 } = require('../shared/deepseek-constants');
 
+
+
+function stripThinkTags(text) {
+  if (typeof text !== 'string' || !text) {
+    return text;
+  }
+  return text.replace(/<\/?\s*think\s*>/gi, '');
+}
+
+function splitThinkingParts(parts) {
+  const out = [];
+  let thinkingDone = false;
+  for (const p of parts) {
+    if (!p) continue;
+    if (thinkingDone && p.type === 'thinking') {
+      const cleaned = stripThinkTags(p.text);
+      if (cleaned) {
+        out.push({ text: cleaned, type: 'text' });
+      }
+      continue;
+    }
+    if (p.type !== 'thinking') {
+      const cleaned = stripThinkTags(p.text);
+      if (cleaned) {
+        out.push({ text: cleaned, type: p.type });
+      }
+      continue;
+    }
+    const match = /<\/\s*think\s*>/i.exec(p.text);
+    if (!match) {
+      out.push(p);
+      continue;
+    }
+    thinkingDone = true;
+    const before = p.text.substring(0, match.index);
+    let after = p.text.substring(match.index + match[0].length);
+    if (before) {
+      out.push({ text: before, type: 'thinking' });
+    }
+    after = stripThinkTags(after);
+    if (after) {
+      out.push({ text: after, type: 'text' });
+    }
+  }
+  return { parts: out, transitioned: thinkingDone };
+}
+
 function parseChunkForContent(chunk, thinkingEnabled, currentType, stripReferenceMarkers = true) {
   if (!chunk || typeof chunk !== 'object') {
     return {
@@ -147,7 +194,11 @@ function parseChunkForContent(chunk, thinkingEnabled, currentType, stripReferenc
 
   let partType = 'text';
   if (pathValue === 'response/thinking_content') {
-    partType = 'thinking';
+    if (newType === 'text') {
+      partType = 'text';
+    } else {
+      partType = 'thinking';
+    }
   } else if (pathValue === 'response/content') {
     partType = 'text';
   } else if (pathValue.includes('response/fragments') && pathValue.includes('/content')) {
@@ -186,9 +237,16 @@ function parseChunkForContent(chunk, thinkingEnabled, currentType, stripReferenc
     if (content) {
       parts.push({ text: content, type: partType });
     }
+    
+    let resolvedParts = filterLeakedContentFilterParts(parts);
+    const splitResult = splitThinkingParts(resolvedParts);
+    if (splitResult.transitioned) {
+      newType = 'text';
+    }
+    
     return {
       parsed: true,
-      parts: filterLeakedContentFilterParts(parts),
+      parts: splitResult.parts,
       finished: false,
       contentFilter: false,
       errorMessage: '',
@@ -213,9 +271,16 @@ function parseChunkForContent(chunk, thinkingEnabled, currentType, stripReferenc
       };
     }
     parts.push(...extracted.parts);
+    
+    let resolvedParts = filterLeakedContentFilterParts(parts);
+    const splitResult = splitThinkingParts(resolvedParts);
+    if (splitResult.transitioned) {
+      newType = 'text';
+    }
+    
     return {
       parsed: true,
-      parts: filterLeakedContentFilterParts(parts),
+      parts: splitResult.parts,
       finished: false,
       contentFilter: false,
       errorMessage: '',
@@ -249,9 +314,16 @@ function parseChunkForContent(chunk, thinkingEnabled, currentType, stripReferenc
       }
     }
   }
+  
+  let resolvedParts = filterLeakedContentFilterParts(parts);
+  const splitResult = splitThinkingParts(resolvedParts);
+  if (splitResult.transitioned) {
+    newType = 'text';
+  }
+
   return {
     parsed: true,
-    parts: filterLeakedContentFilterParts(parts),
+    parts: splitResult.parts,
     finished: false,
     contentFilter: false,
     errorMessage: '',
@@ -546,4 +618,5 @@ module.exports = {
   isFragmentStatusPath,
   isCitation,
   stripReferenceMarkers: stripReferenceMarkersText,
+  stripThinkTags,
 };

internal/sse/parser.go

@@ -273,7 +273,10 @@ func splitThinkingParts(parts []ContentPart) ([]ContentPart, bool) {
 			continue
 		}
 		if p.Type != "thinking" {
-			out = append(out, p)
+			cleaned := stripThinkTags(p.Text)
+			if cleaned != "" {
+				out = append(out, ContentPart{Text: cleaned, Type: p.Type})
+			}
 			continue
 		}
 		loc := thinkClosePattern.FindStringIndex(p.Text)
@@ -294,7 +297,8 @@ func splitThinkingParts(parts []ContentPart) ([]ContentPart, bool) {
 		}
 	}
 	if !thinkingDone {
-		return parts, false
+		// Return 'out' instead of 'parts' because text parts might have been cleaned via stripThinkTags
+		return out, false
 	}
 	return out, true
 }

internal/sse/parser_test.go

@@ -149,3 +149,17 @@ func TestParseSSEChunkForContentAutoTransitionsState(t *testing.T) {
 		t.Fatalf("expected nextType2 to remain text, got %q", nextType2)
 	}
 }
+
+func TestParseSSEChunkForContentStripsLeakedThinkTagsFromText(t *testing.T) {
+	chunk := map[string]any{
+		"p": "response/content", // This makes the part type "text"
+		"v": "normal text <think>leaked</think> end",
+	}
+	parts, _, _ := ParseSSEChunkForContent(chunk, true, "text")
+	if len(parts) != 1 {
+		t.Fatalf("expected 1 part, got %d: %#v", len(parts), parts)
+	}
+	if parts[0].Type != "text" || parts[0].Text != "normal text leaked end" {
+		t.Fatalf("expected leaked think tag to be stripped, got %#v", parts[0])
+	}
+}