From c0df7b2dbf6c9a9ec9cd52c2cf75433baf68ed0d Mon Sep 17 00:00:00 2001
From: rambo <luwei.li@17zuoye.com>
Date: Fri, 16 Jan 2026 12:40:11 +0800
Subject: [PATCH] fix(pool): add useH2c option support for multiple connections

The Pool class was not passing the useH2c option to buildConnector
and kOptions, causing HTTPParserError when using Agent with useH2c
and connections > 1.

This fix ensures that:
- useH2c is extracted from constructor parameters
- useH2c is passed to buildConnector for proper connection setup
- useH2c is included in kOptions for client instances

Fixes issue with h2c (HTTP/2 Cleartext) failing on second connection
when Pool creates multiple Client instances.

Before: connections > 1 with useH2c caused HTTP/1.1 parser to receive
        HTTP/2 binary frames, resulting in protocol mismatch error
After:  All connections properly use HTTP/2 cleartext protocol

Fixes #4737
---
 lib/dispatcher/pool.js | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/lib/dispatcher/pool.js b/lib/dispatcher/pool.js
index 77fd5326696..35f335ff857 100644
--- a/lib/dispatcher/pool.js
+++ b/lib/dispatcher/pool.js
@@ -36,6 +36,7 @@ class Pool extends PoolBase {
     autoSelectFamily,
     autoSelectFamilyAttemptTimeout,
     allowH2,
+    useH2c,
     clientTtl,
     ...options
   } = {}) {
@@ -56,6 +57,7 @@ class Pool extends PoolBase {
         ...tls,
         maxCachedSessions,
         allowH2,
+        useH2c,
         socketPath,
         timeout: connectTimeout,
         ...(typeof autoSelectFamily === 'boolean' ? { autoSelectFamily, autoSelectFamilyAttemptTimeout } : undefined),
@@ -67,7 +69,7 @@ class Pool extends PoolBase {
 
     this[kConnections] = connections || null
     this[kUrl] = util.parseOrigin(origin)
-    this[kOptions] = { ...util.deepClone(options), connect, allowH2, clientTtl }
+    this[kOptions] = { ...util.deepClone(options), connect, allowH2, useH2c, clientTtl }
     this[kOptions].interceptors = options.interceptors
       ? { ...options.interceptors }
       : undefined