diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index fdc66b1e9cb..312cd6e2610 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -270,10 +270,11 @@ jobs:
       fail-fast: false
       max-parallel: 0
       matrix:
-        # Node.js 22 is intentionally excluded here: --shared-builtin-undici/undici-path
-        # embedding is only validated for supported/current majors.
-        # Start validating shared builtin embedding from Node.js 26 onward.
-        node-version: ['26']
+        # Node.js 20 and 22 are intentionally excluded here because
+        # --shared-builtin-undici/undici-path still hits upstream Node.js issues there.
+        # Keep validating supported/current majors, and start exercising 26
+        # automatically once a release is available.
+        node-version: ['24', '25', '26']
         runs-on: ['ubuntu-latest']
     with:
       node-version: ${{ matrix.node-version }}
diff --git a/lib/dispatcher/env-http-proxy-agent.js b/lib/dispatcher/env-http-proxy-agent.js
index df2e9fec9f4..f88437f1936 100644
--- a/lib/dispatcher/env-http-proxy-agent.js
+++ b/lib/dispatcher/env-http-proxy-agent.js
@@ -10,22 +10,6 @@ const DEFAULT_PORTS = {
   'https:': 443
 }
 
-/**
- * Normalizes a proxy URL by prepending a scheme if one is missing.
- * This matches the behavior of curl and Go's httpproxy package, which
- * assume http:// for scheme-less proxy values.
- *
- * @param {string} proxyUrl - The proxy URL to normalize
- * @param {string} defaultScheme - The scheme to prepend if missing ('http' or 'https')
- * @returns {string} The normalized proxy URL
- */
-function normalizeProxyUrl (proxyUrl, defaultScheme) {
-  if (!proxyUrl) return proxyUrl
-  // If the value already contains a scheme (e.g. http://, https://, socks5://), return as-is
-  if (/^[a-z][a-z0-9+\-.]*:\/\//i.test(proxyUrl)) return proxyUrl
-  return `${defaultScheme}://${proxyUrl}`
-}
-
 class EnvHttpProxyAgent extends DispatcherBase {
   #noProxyValue = null
   #noProxyEntries = null
@@ -39,20 +23,14 @@ class EnvHttpProxyAgent extends DispatcherBase {
 
     this[kNoProxyAgent] = new Agent(agentOpts)
 
-    const HTTP_PROXY = normalizeProxyUrl(
-      httpProxy ?? process.env.http_proxy ?? process.env.HTTP_PROXY,
-      'http'
-    )
+    const HTTP_PROXY = httpProxy ?? process.env.http_proxy ?? process.env.HTTP_PROXY
     if (HTTP_PROXY) {
       this[kHttpProxyAgent] = new ProxyAgent({ ...agentOpts, uri: HTTP_PROXY })
     } else {
       this[kHttpProxyAgent] = this[kNoProxyAgent]
     }
 
-    const HTTPS_PROXY = normalizeProxyUrl(
-      httpsProxy ?? process.env.https_proxy ?? process.env.HTTPS_PROXY,
-      'https'
-    )
+    const HTTPS_PROXY = httpsProxy ?? process.env.https_proxy ?? process.env.HTTPS_PROXY
     if (HTTPS_PROXY) {
       this[kHttpsProxyAgent] = new ProxyAgent({ ...agentOpts, uri: HTTPS_PROXY })
     } else {
diff --git a/test/env-http-proxy-agent.js b/test/env-http-proxy-agent.js
index bf061704906..97969cfaf20 100644
--- a/test/env-http-proxy-agent.js
+++ b/test/env-http-proxy-agent.js
@@ -124,61 +124,6 @@ test('prefers lowercase over uppercase env vars even when empty', async (t) => {
   return dispatcher.close()
 })
 
-test('handles scheme-less HTTP_PROXY by assuming http://', async (t) => {
-  t = tspl(t, { plan: 2 })
-  process.env.HTTP_PROXY = 'example.com:8080'
-  const dispatcher = new EnvHttpProxyAgent()
-  t.ok(dispatcher[kHttpProxyAgent] instanceof ProxyAgent)
-  t.equal(dispatcher[kHttpProxyAgent][kProxy].uri, 'http://example.com:8080/')
-  return dispatcher.close()
-})
-
-test('handles scheme-less HTTPS_PROXY by assuming https://', async (t) => {
-  t = tspl(t, { plan: 2 })
-  process.env.HTTPS_PROXY = 'example.com:8443'
-  const dispatcher = new EnvHttpProxyAgent()
-  t.ok(dispatcher[kHttpsProxyAgent] instanceof ProxyAgent)
-  t.equal(dispatcher[kHttpsProxyAgent][kProxy].uri, 'https://example.com:8443/')
-  return dispatcher.close()
-})
-
-test('handles scheme-less httpProxy option by assuming http://', async (t) => {
-  t = tspl(t, { plan: 2 })
-  const dispatcher = new EnvHttpProxyAgent({ httpProxy: 'myproxy:9000' })
-  t.ok(dispatcher[kHttpProxyAgent] instanceof ProxyAgent)
-  t.equal(dispatcher[kHttpProxyAgent][kProxy].uri, 'http://myproxy:9000/')
-  return dispatcher.close()
-})
-
-test('handles scheme-less httpsProxy option by assuming https://', async (t) => {
-  t = tspl(t, { plan: 2 })
-  const dispatcher = new EnvHttpProxyAgent({ httpsProxy: 'myproxy:9443' })
-  t.ok(dispatcher[kHttpsProxyAgent] instanceof ProxyAgent)
-  t.equal(dispatcher[kHttpsProxyAgent][kProxy].uri, 'https://myproxy:9443/')
-  return dispatcher.close()
-})
-
-test('does not modify proxy URLs that already have a scheme', async (t) => {
-  t = tspl(t, { plan: 4 })
-  process.env.HTTP_PROXY = 'http://example.com:8080'
-  process.env.HTTPS_PROXY = 'http://example.com:8443'
-  const dispatcher = new EnvHttpProxyAgent()
-  t.ok(dispatcher[kHttpProxyAgent] instanceof ProxyAgent)
-  t.equal(dispatcher[kHttpProxyAgent][kProxy].uri, 'http://example.com:8080/')
-  t.ok(dispatcher[kHttpsProxyAgent] instanceof ProxyAgent)
-  t.equal(dispatcher[kHttpsProxyAgent][kProxy].uri, 'http://example.com:8443/')
-  return dispatcher.close()
-})
-
-test('handles scheme-less hostname-only proxy values', async (t) => {
-  t = tspl(t, { plan: 2 })
-  process.env.HTTP_PROXY = 'myproxy'
-  const dispatcher = new EnvHttpProxyAgent()
-  t.ok(dispatcher[kHttpProxyAgent] instanceof ProxyAgent)
-  t.equal(dispatcher[kHttpProxyAgent][kProxy].uri, 'http://myproxy/')
-  return dispatcher.close()
-})
-
 test('creates a proxy agent only for https when only https_proxy is set', async (t) => {
   t = tspl(t, { plan: 5 })
   process.env.https_proxy = 'http://example.com:8443'