fix(sse): make CRLF normalization chunk-boundary safe (#1359)

* fix(sse): handle CRLF split across chunk boundaries

* style: apply prettier formatting

src/glmt/sse-parser.ts

@@ -35,12 +35,14 @@ export class SSEParser {
   private eventCount: number;
   private maxBufferSize: number;
   private throwOnMalformedJson: boolean;
+  private pendingCR: boolean;
 
   constructor(options: SSEParserOptions = {}) {
     this.buffer = '';
     this.eventCount = 0;
     this.maxBufferSize = options.maxBufferSize || 1024 * 1024; // 1MB default
     this.throwOnMalformedJson = options.throwOnMalformedJson === true;
+    this.pendingCR = false;
   }
 
   /**
@@ -49,7 +51,19 @@ export class SSEParser {
    * @returns Array of parsed events
    */
   parse(chunk: Buffer | string): SSEEvent[] {
-    this.buffer += chunk.toString().replace(/\r\n?/g, '\n');
+    let normalizedChunk = chunk.toString();
+
+    if (this.pendingCR) {
+      if (normalizedChunk.startsWith('\n')) {
+        normalizedChunk = normalizedChunk.slice(1);
+      }
+      this.pendingCR = false;
+    }
+
+    const endsWithCR = normalizedChunk.endsWith('\r');
+    normalizedChunk = normalizedChunk.replace(/\r\n?/g, '\n');
+    this.pendingCR = endsWithCR;
+    this.buffer += normalizedChunk;
 
     // C-01 Fix: Prevent unbounded buffer growth (DoS protection)
     if (this.buffer.length > this.maxBufferSize) {
@@ -127,5 +141,6 @@ export class SSEParser {
   reset(): void {
     this.buffer = '';
     this.eventCount = 0;
+    this.pendingCR = false;
   }
 }

tests/unit/glmt/sse-parser.test.ts

@@ -46,4 +46,18 @@ describe('SSEParser', () => {
         ?.delta?.content
     ).toBe('Legacy');
   });
+
+
+  it('does not split events when CRLF is split across chunks', () => {
+    const parser = new SSEParser({ throwOnMalformedJson: true });
+
+    expect(parser.parse('data: {"choices":[\r')).toEqual([]);
+    const events = parser.parse('\ndata: {"delta":{"content":"Hello"}}\r\ndata: ]}\r\n\r\n');
+
+    expect(events).toHaveLength(1);
+    expect(
+      (events[0]?.data as { choices?: Array<{ delta?: { content?: string } }> })?.choices?.[0]
+        ?.delta?.content
+    ).toBe('Hello');
+  });
 });