From 548b21faece8338061c054faab498663deb29a22 Mon Sep 17 00:00:00 2001
From: Matt Carey <mcarey@cloudflare.com>
Date: Tue, 2 Dec 2025 12:33:36 +0000
Subject: [PATCH] fix: release HTTP connections after POST responses in SSE and
 streamableHttp transports

---
 src/client/sse.ts            | 3 +++
 src/client/streamableHttp.ts | 4 ++++
 2 files changed, 7 insertions(+)

diff --git a/src/client/sse.ts b/src/client/sse.ts
index 2b0661958..f0e91ff25 100644
--- a/src/client/sse.ts
+++ b/src/client/sse.ts
@@ -281,6 +281,9 @@ export class SSEClientTransport implements Transport {
 
                 throw new Error(`Error POSTing to endpoint (HTTP ${response.status}): ${text}`);
             }
+
+            // Release connection - POST responses don't have content we need
+            await response.body?.cancel();
         } catch (error) {
             this.onerror?.(error as Error);
             throw error;
diff --git a/src/client/streamableHttp.ts b/src/client/streamableHttp.ts
index 9cc4887df..3b31a9286 100644
--- a/src/client/streamableHttp.ts
+++ b/src/client/streamableHttp.ts
@@ -592,8 +592,12 @@ export class StreamableHTTPClientTransport implements Transport {
                         this.onmessage?.(msg);
                     }
                 } else {
+                    await response.body?.cancel();
                     throw new StreamableHTTPError(-1, `Unexpected content type: ${contentType}`);
                 }
+            } else {
+                // No requests in message but got 200 OK - still need to release connection
+                await response.body?.cancel();
             }
         } catch (error) {
             this.onerror?.(error as Error);