feat: increase SSE scanner buffer to 4MB for Anthropic tool calls, add stream error handling, prune unused Go dependencies, and add setup instructions.

handlers/anthropic.go

@@ -306,6 +306,11 @@ func handleStreaming(
 
 	c.Response().SetBodyStreamWriter(func(w *bufio.Writer) {
 		scanner := bufio.NewScanner(resp.Body)
+
+		const maxScanTokenSize = 4 * 1024 * 1024 // 4 MB — Claude Code tool calls produce large chunks
+		buf := make([]byte, maxScanTokenSize)
+		scanner.Buffer(buf, maxScanTokenSize)
+
 		for scanner.Scan() {
 			line := scanner.Text()
 			if !strings.HasPrefix(line, "data: ") {
@@ -314,10 +319,20 @@ func handleStreaming(
 			chunk := []byte(strings.TrimPrefix(line, "data: "))
 			event := transformer.TransformChunk(chunk)
 			if event != "" {
-				w.WriteString(event)
-				w.Flush()
+				if _, err := w.WriteString(event); err != nil {
+					logger.Warn("[ANTHROPIC] Stream write error [IP: %s]: %v", c.IP(), err)
+					return
+				}
+				if err := w.Flush(); err != nil {
+					logger.Warn("[ANTHROPIC] Stream flush error [IP: %s]: %v", c.IP(), err)
+					return
+				}
 			}
 		}
+		if err := scanner.Err(); err != nil {
+			logger.Warn("[ANTHROPIC] Stream scan error [IP: %s]: %v", c.IP(), err)
+			return
+		}
 		// Ensure final events are sent
 		final := transformer.TransformChunk([]byte("[DONE]"))
 		if final != "" {