[edsonsims]

Passing a URL instance retains the caller's mutable object. Changing its path or query after construction changes EventSource.url and the next reconnection target, even though the initial request used the original URL.

I copy that URL during construction. This keeps the initial URL record stable, consistent with the EventSource constructor and URL getter. The existing string, redirect and custom-fetch paths retain their handling. Two real-HTTP regressions cover the exposed URL and reconnection destination; both fail against the original source.

Validation on Node 24.19.0/macOS arm64:

• Node: 75 passed, 1 skipped; build, public types, lint and formatting pass.
• Chromium: 76 passed. WebKit: 72 passed, 4 existing skips.
• Happy DOM: 72 passed, 4 existing expected failures. Workerd: 68 passed, 7 existing expected failures, 1 skip in a sequential full run.
• An owned loopback probe confirms that changing the original object's path/query no longer changes either request destination.

Firefox could not launch locally (Could not find profile folder), so no Firefox test result is claimed. Bun, Deno and iOS were not run.

[rexxars]

Thank you for finding and fixing the issue!