diff --git a/nodejs/test/e2e/harness/sdkTestContext.ts b/nodejs/test/e2e/harness/sdkTestContext.ts
index 624450e47c..3e4c3a0560 100644
--- a/nodejs/test/e2e/harness/sdkTestContext.ts
+++ b/nodejs/test/e2e/harness/sdkTestContext.ts
@@ -291,16 +291,44 @@ export async function createSdkTestContext({
     });
 
     afterAll(async () => {
-        await copilotClient.stop();
-        await openAiEndpoint.stop(anyTestFailed);
+        removeDisconnectedSessionEntries(copilotClient);
+        const stopErrors = await copilotClient.stop();
+        let proxyStopError: unknown;
+        try {
+            await openAiEndpoint.stop(anyTestFailed);
+        } catch (error) {
+            proxyStopError = error;
+        }
         await rmDir("remove e2e test copilotHomeDir", copilotHomeDir);
         await rmDir("remove e2e test homeDir", homeDir);
         await rmDir("remove e2e test workDir", workDir);
+        if (stopErrors.length > 0) {
+            throw new AggregateError(stopErrors, "Copilot client cleanup failed");
+        }
+        if (proxyStopError) {
+            throw proxyStopError;
+        }
     });
 
     return harness;
 }
 
+function removeDisconnectedSessionEntries(client: CopilotClient): void {
+    // `CopilotSession.disconnect()` leaves its object in the client's private registry.
+    // The in-process client stop path aborts every registry entry, including these
+    // already-destroyed sessions. Remove only stale test entries before teardown.
+    const sessions = (
+        client as unknown as {
+            sessions: Map<string, { disconnected: boolean }>;
+        }
+    ).sessions;
+    for (const [sessionId, session] of sessions) {
+        if (session.disconnected) {
+            sessions.delete(sessionId);
+        }
+    }
+}
+
 function getTrafficCapturePath(testContext: TestContext): string {
     const testFilePath = testContext.task.file.filepath;
     const suffix = ".test.ts";