fix: handle incomplete JSON in SSE streaming responses

Buffer partial JSON data when network packets split `data:` lines mid-JSON,
preventing "Unexpected identifier" parse errors during streaming translations

Author: liby

.github/workflows/lint.yaml

@@ -0,0 +1,21 @@
+name: Lint
+
+on:
+  push:
+  pull_request:
+
+jobs:
+  lint:
+    runs-on: ubuntu-latest
+
+    steps:
+      - uses: actions/checkout@v4
+
+      - uses: oven-sh/setup-bun@v2
+        with:
+          bun-version: latest
+
+      - run: bun install
+
+      - name: Run Biome checks
+        run: bun run lint

.github/workflows/release.yaml

@@ -50,9 +50,6 @@ jobs:
 
       - run: bun install
 
-      - name: Run Biome checks
-        run: bun run lint
-
       - name: Package plugin and update appcast
         env:
           VERSION_NUMBER: ${{ env.VERSION_NUMBER }}

biome.json

@@ -5,6 +5,10 @@
     "clientKind": "git",
     "useIgnoreFile": true
   },
+  "files": {
+    "ignoreUnknown": false,
+    "includes": ["**", "!appcast.json"]
+  },
   "formatter": {
     "enabled": true,
     "indentStyle": "space"

src/adapter/openai.ts

@@ -19,6 +19,7 @@ import { BaseAdapter } from './base';
 
 export class OpenAiAdapter extends BaseAdapter {
   private buffer = '';
+  private dataBuffer = ''; // Buffer for incomplete JSON data within a single data: line
 
   constructor(config?: ServiceAdapterConfig) {
     super(
@@ -182,6 +183,40 @@ export class OpenAiAdapter extends BaseAdapter {
     return null;
   }
 
+  private isLikelyIncompleteJSON(str: string): boolean {
+    // Simple heuristic: if parsing fails, check if we have unmatched brackets
+    // This avoids complex parsing and handles most streaming JSON cases
+    try {
+      JSON.parse(str);
+      return false; // Valid JSON, not incomplete
+    } catch {
+      // Check for common incomplete JSON patterns
+      // Remove all escaped characters and strings to simplify bracket counting
+      const simplified = str
+        .replace(/\\./g, '') // Remove escaped characters
+        .replace(/"[^"]*"/g, '""'); // Replace string contents with empty strings
+
+      // Count unmatched brackets
+      const openBraces = (simplified.match(/{/g) || []).length;
+      const closeBraces = (simplified.match(/}/g) || []).length;
+      const openBrackets = (simplified.match(/\[/g) || []).length;
+      const closeBrackets = (simplified.match(/]/g) || []).length;
+
+      // Also check if string ends with incomplete patterns
+      const endsWithIncomplete =
+        /[,:]\s*$/.test(str) || // Ends with comma or colon
+        /"\s*$/.test(str) || // Ends with quote
+        /\\$/.test(str); // Ends with escape
+
+      // Likely incomplete if brackets don't match or has incomplete ending
+      return (
+        openBraces !== closeBraces ||
+        openBrackets !== closeBrackets ||
+        endsWithIncomplete
+      );
+    }
+  }
+
   public handleStream(
     streamData: { text: string },
     query: TextTranslateQuery,
@@ -245,8 +280,12 @@ export class OpenAiAdapter extends BaseAdapter {
 
       // Only process response.output_text.delta events
       if (eventType === 'response.output_text.delta' && eventData) {
+        // Combine with any buffered data from previous incomplete JSON
+        const dataToProcess = this.dataBuffer + eventData;
+        this.dataBuffer = '';
+
         try {
-          const dataObj = JSON.parse(eventData);
+          const dataObj = JSON.parse(dataToProcess);
           if (dataObj.delta) {
             targetText += dataObj.delta;
             query.onStream({
@@ -258,14 +297,25 @@ export class OpenAiAdapter extends BaseAdapter {
             });
           }
         } catch (error) {
-          // Log error for debugging but continue processing
-          if (error instanceof Error) {
-            console.error(
-              'Failed to parse SSE data:',
-              error.message,
-              'Data:',
-              eventData,
-            );
+          // Check if this might be incomplete JSON
+          if (
+            error instanceof SyntaxError &&
+            this.isLikelyIncompleteJSON(dataToProcess)
+          ) {
+            // Buffer the incomplete JSON for next iteration
+            this.dataBuffer = dataToProcess;
+          } else {
+            // This is a real parsing error, log it but continue
+            if (error instanceof Error) {
+              console.error(
+                'Failed to parse SSE data:',
+                error.message,
+                'Data:',
+                dataToProcess,
+              );
+            }
+            // Clear the buffer on real errors
+            this.dataBuffer = '';
           }
         }
       }