fix: add buffer for SSE stream parsing to prevent truncated words

src/services/deepseek.ts

@@ -112,29 +112,53 @@ export async function sendMessageStream(
 
   const decoder = new TextDecoder();
   let fullContent = "";
+  let buffer = ""; // Buffer for incomplete lines
 
   while (true) {
     const { done, value } = await reader.read();
     if (done) break;
 
-    const chunk = decoder.decode(value, { stream: true });
-    const lines = chunk.split("\n").filter((line) => line.trim() !== "");
+    // Append new data to buffer
+    buffer += decoder.decode(value, { stream: true });
+    
+    // Process complete lines only
+    const lines = buffer.split("\n");
+    // Keep last incomplete line in buffer
+    buffer = lines.pop() || "";
 
     for (const line of lines) {
-      if (line.startsWith("data: ")) {
-        const data = line.slice(6);
-        if (data === "[DONE]") continue;
+      const trimmed = line.trim();
+      if (!trimmed || !trimmed.startsWith("data: ")) continue;
       
-        try {
-          const parsed = JSON.parse(data);
-          const content = parsed.choices?.[0]?.delta?.content || "";
-          if (content) {
-            fullContent += content;
-            onChunk(content);
-          }
-        } catch {
-          // Ignore parse errors
+      const data = trimmed.slice(6);
+      if (data === "[DONE]") continue;
+
+      try {
+        const parsed = JSON.parse(data);
+        const content = parsed.choices?.[0]?.delta?.content || "";
+        if (content) {
+          fullContent += content;
+          onChunk(content);
         }
+      } catch {
+        // Incomplete JSON - will be handled in next chunk
+      }
+    }
+  }
+
+  // Process any remaining buffer
+  if (buffer.trim().startsWith("data: ")) {
+    const data = buffer.trim().slice(6);
+    if (data !== "[DONE]") {
+      try {
+        const parsed = JSON.parse(data);
+        const content = parsed.choices?.[0]?.delta?.content || "";
+        if (content) {
+          fullContent += content;
+          onChunk(content);
+        }
+      } catch {
+        // Ignore final parse error
       }
     }
   }