diff --git a/scripts/scenarios/start-app.ts b/scripts/scenarios/start-app.ts
index 5dee3f26c1..27e13cb002 100644
--- a/scripts/scenarios/start-app.ts
+++ b/scripts/scenarios/start-app.ts
@@ -22,7 +22,7 @@ import { ScenarioError } from "./shell.ts";
 // The dev runner's web port is 5733 plus an offset. Mirror of BASE_WEB_PORT in dev-runner.ts.
 const BASE_WEB_PORT = 5733;
 // The replay agent `vp run dev` registers: free, recorded turns through the real adapter.
-const REPLAY = { instanceId: "devReplay", model: "showcase" };
+const REPLAY = { instanceId: "proofReplay", model: "delegation" };
 // Generated text (titles) cannot go to the replay agent: the server swaps an ACP agent for the
 // first enabled real provider, else its default, Codex. So every provider it could fall back to
 // is off and Codex is a command that only fails: no run reaches a paid model.
@@ -71,14 +71,14 @@ const prepareHome = Effect.fn("startApp.prepareHome")(function* (home: string) {
     yield* encodeSettings({
       defaultModelSelection: REPLAY,
       providerInstances: Object.fromEntries(
-        REAL_PROVIDERS.map((driver) => [
+        [["proofReplay", {driver: "acpRegistry", displayName: "Delegation replay", enabled: true, config: {source: "local", commandPath: process.execPath, commandArgs: [process.env.T3_PROOF_AGENT_PATH]}}], ...REAL_PROVIDERS.map((driver) => [
           driver,
           {
             driver,
             enabled: false,
             ...(driver === "codex" ? { config: { binaryPath: noModel } } : {}),
           },
-        ]),
+        ])],
       ),
     }),
   );
diff --git a/scripts/scenarios/t3.ts b/scripts/scenarios/t3.ts
index 24bb6e73d3..dbb1b46389 100644
--- a/scripts/scenarios/t3.ts
+++ b/scripts/scenarios/t3.ts
@@ -155,7 +155,7 @@ export const test = base.extend<{ t3: T3 }>({
         await expect(browser).not.toHaveURL(/\/pair(?:[?#]|$)/, { timeout: 60_000 });
         if (typeof target !== "string") {
           const environment = await runPromise(environmentId(app.baseUrl ?? ""));
-          await app.open(`/${environment}/${target.threadId}`);
+          await app.open(`/${environment}/${encodeURIComponent(target.threadId)}`);
         } else if (target !== "/") await app.open(target);
       },
     });