Reset smoke idempotence state

Clear the Fedify harness inbox idempotence keys when the smoke test reset
endpoint is called.  This keeps repeated Sharkey follow/unfollow scenarios
from being filtered as duplicate activities after the visible test inbox has
already been cleared.

Fixes #749

Assisted-by: Codex:gpt-5.5

Author: dahlia

test/smoke/harness/backdoor.ts

@@ -1,5 +1,6 @@
 import type { Federation } from "@fedify/fedify/federation";
 import { Create, Follow, Note, Undo } from "@fedify/vocab";
+import { resetFederationTestState } from "./federation.ts";
 import { store } from "./store.ts";
 
 function json(data: unknown, status = 200): Response {
@@ -80,6 +81,7 @@ export async function handleBackdoor(
   if (url.pathname === "/_test/reset" && request.method === "POST") {
     store.clear();
     recipientCache.clear();
+    await resetFederationTestState();
     return json({ ok: true });
   }
 

test/smoke/harness/federation.ts

@@ -7,14 +7,23 @@ const ORIGIN = Deno.env.get("HARNESS_ORIGIN") ??
   "http://fedify-harness:3001";
 
 const rsaKeyPair = await generateCryptoKeyPair("RSASSA-PKCS1-v1_5");
+const kv = new MemoryKvStore();
 
 const federation = createFederation<void>({
-  kv: new MemoryKvStore(),
+  kv,
   origin: ORIGIN,
   allowPrivateAddress: true,
   skipSignatureVerification: !Deno.env.get("STRICT_MODE"),
 });
 
+export async function resetFederationTestState(): Promise<void> {
+  const keys = [];
+  for await (const entry of kv.list(["_fedify", "activityIdempotence"])) {
+    keys.push(entry.key);
+  }
+  await Promise.all(keys.map((key) => kv.delete(key)));
+}
+
 federation
   .setActorDispatcher("/users/{identifier}", async (ctx, identifier) => {
     if (identifier !== "testuser") return null;