fix: properly manage request context lifecycle by moving cancel calls to appropriate error and completion paths

handlers/anthropic.go

@@ -271,10 +271,10 @@ func handleStreaming(
 ) error {
 	// Direct HTTP request to upstream (bypass proxy.Forward for streaming)
 	ctx, cancel := context.WithTimeout(c.Context(), time.Duration(cfg.RequestTimeoutSeconds)*time.Second)
-	defer cancel()
 
 	req, err := http.NewRequestWithContext(ctx, "POST", targetURL, bytes.NewReader(body))
 	if err != nil {
+		cancel()
 		return c.Status(fiber.StatusInternalServerError).SendString("build request failed")
 	}
 	for key, vals := range headers {
@@ -287,11 +287,13 @@ func handleStreaming(
 	client := &http.Client{}
 	resp, err := client.Do(req)
 	if err != nil {
+		cancel()
 		logger.Warn("[ANTHROPIC] Stream error [IP: %s]: %v", c.IP(), err)
 		return c.Status(fiber.StatusBadGateway).SendString("upstream error")
 	}
 
 	if resp.StatusCode != 200 {
+		cancel()
 		defer resp.Body.Close()
 		body, _ := io.ReadAll(resp.Body)
 		logger.Warn("[ANTHROPIC] Stream upstream %d [IP: %s]: %s", resp.StatusCode, c.IP(), string(body))
@@ -308,6 +310,7 @@ func handleStreaming(
 	c.Set("Connection", "keep-alive")
 
 	c.Response().SetBodyStreamWriter(func(w *bufio.Writer) {
+		defer cancel()
 		defer resp.Body.Close()
 
 		scanner := bufio.NewScanner(resp.Body)