fix(react): normalize event stream URLs

Normalize the React event-stream base URL consistently with evaluation requests so trailing slashes do not request a double-slash path. Include regression coverage and an Unreleased entry.

Co-authored-by: Sebastien Tardif <sebtardif@ncf.ca>

Author: SebTardif

CHANGELOG.md

@@ -6,6 +6,7 @@ All notable changes to Krillswitch are documented in this file.
 
 ### Fixed
 
+- Strip a trailing slash from the React event-stream URL so a base URL ending in `/` connects to `/v1/stream`. Thanks @SebTardif.
 - Bound GitHub organization membership checks to five seconds during sign-in, including response-body reads, while preserving cached membership on network failure. Thanks @SebTardif.
 - Abort webhook deliveries after two seconds, record timeout status, and keep unattempted entries queued without delaying other subscribers. Thanks @SebTardif.
 - Abort CLI API requests and response-body reads after a new 30-second default deadline, report timeout errors clearly, and support `KRILLSWITCH_TIMEOUT_MS` overrides (`0` restores unlimited waits). Thanks @SebTardif.

packages/react/src/krillswitch.test.tsx

@@ -712,6 +712,20 @@ describe("stream", () => {
     );
   });
 
+  it("strips a trailing slash from the stream URL the same way eval does", async () => {
+    fetchMock.mockResolvedValue(evalResponse({ souls: false }));
+    render(
+      <FeatureFlagProvider evalKey={EVAL_KEY} baseUrl={`${BASE_URL}/`} stream>
+        <SoulsProbe />
+      </FeatureFlagProvider>,
+    );
+    await waitFor(() => expect(FakeEventSource.instances.length).toBe(1));
+    expect(FakeEventSource.instances[0]?.url).toBe(
+      `${BASE_URL}/v1/stream?key=${encodeURIComponent(EVAL_KEY)}`,
+    );
+    expect(FakeEventSource.instances[0]?.url).not.toContain("//v1/stream");
+  });
+
   it("closes the stream on unmount and never opens one without the option", async () => {
     fetchMock.mockResolvedValue(evalResponse({ souls: false }));
     const withStream = render(

packages/react/src/krillswitch.tsx

@@ -276,7 +276,7 @@ function createClient<M extends FlagManifest>(
       let eventSource: EventSource | null = null;
       if (stream && typeof EventSource !== "undefined") {
         eventSource = new EventSource(
-          `${baseUrl}/v1/stream?key=${encodeURIComponent(evalKey)}`,
+          `${baseUrl.replace(/\/+$/, "")}/v1/stream?key=${encodeURIComponent(evalKey)}`,
         );
         eventSource.addEventListener("change", () => void refresh());
       }