From 8ec64547e7b561e77cb170c69c57bcbda66bf626 Mon Sep 17 00:00:00 2001
From: Karl Seguin <k@openmymind.io>
Date: Thu, 16 Jul 2026 08:06:43 +0800
Subject: [PATCH] Fix: Allow EventSource with relative URLs

---
 src/browser/tests/net/eventsource.html | 17 +++++++++++++++++
 src/browser/webapi/net/EventSource.zig |  2 +-
 2 files changed, 18 insertions(+), 1 deletion(-)

diff --git a/src/browser/tests/net/eventsource.html b/src/browser/tests/net/eventsource.html
index ce2855a89..99e90950f 100644
--- a/src/browser/tests/net/eventsource.html
+++ b/src/browser/tests/net/eventsource.html
@@ -49,6 +49,23 @@
 }
 </script>
 
+<script id=relative_url type=module>
+{
+  const state = await testing.async();
+  const es = new EventSource('/sse/simple');
+  testing.expectEqual('http://127.0.0.1:9582/sse/simple', es.url);
+  es.onerror = () => { throw new Error('unexpected error'); };
+  es.onmessage = (e) => {
+    es.close();
+    state.resolve(e.data);
+  };
+
+  await state.done((data) => {
+    testing.expectEqual('first', data);
+  });
+}
+</script>
+
 <script id=streaming type=module>
 {
   // The server only sends "second" after seeing our /sse/flag request, which
diff --git a/src/browser/webapi/net/EventSource.zig b/src/browser/webapi/net/EventSource.zig
index 546e2c20e..9f3a42b75 100644
--- a/src/browser/webapi/net/EventSource.zig
+++ b/src/browser/webapi/net/EventSource.zig
@@ -116,7 +116,7 @@ pub fn init(url: []const u8, opts_: ?Opts, exec: *const Execution) !*EventSource
         log.debug(.http, "EventSource connecting", .{ .url = resolved });
     }
 
-    if (std.ascii.startsWithIgnoreCase(url, "http://") == false and std.ascii.startsWithIgnoreCase(url, "https://") == false) {
+    if (std.ascii.startsWithIgnoreCase(resolved, "http://") == false and std.ascii.startsWithIgnoreCase(resolved, "https://") == false) {
         try self.scheduleTask(failConnection, 0, "EventSource.fail");
         return self;
     }