diff --git a/tests/runner-e2e/runner.spec.ts b/tests/runner-e2e/runner.spec.ts
index b37debb0e02..5e4de77ee77 100644
--- a/tests/runner-e2e/runner.spec.ts
+++ b/tests/runner-e2e/runner.spec.ts
@@ -550,6 +550,7 @@ for (const execution of executions) {
     let selectedRuns: RunRecord[] = [];
     let runtimeLeases: EnvironmentLeaseRecord[] = [];
     let matcherResults: MatcherResult[] = [];
+    let downloadedResponseProof: Awaited<ReturnType<typeof readResponseProof>> | undefined;
     let firstTaskEvidence: RunnerE2EResult["firstTask"];
     let turnTimings: NonNullable<RunnerE2EResult["turnTimings"]> | undefined;
     const turnSubmissionTimesMs: number[] = [];
@@ -1953,9 +1954,9 @@ for (const execution of executions) {
         ),
       );
       if (execution.suite.id === "api-response-reading") {
-        const proof = await readResponseProof(api, issue.id, run.id);
-        fileObservations["api-response-proof.txt"] = proof.content;
-        await writeSanitizedJson(snapshotsDir, "downloaded-response-proof.json", proof, secrets);
+        downloadedResponseProof = await readResponseProof(api, issue.id, run.id);
+        fileObservations["api-response-proof.txt"] = downloadedResponseProof.content;
+        await writeSanitizedJson(snapshotsDir, "downloaded-response-proof.json", downloadedResponseProof, secrets);
       }
       matcherResults = await Promise.all(
         taskMatchers.map((matcher) =>
@@ -2417,7 +2418,13 @@ for (const execution of executions) {
       const visibleAgentReplies = page
         .getByTestId("task-chat-thread")
         .getByTestId("task-chat-agent-bubble");
-      if (execution.task.flow === "warm_three_turn") {
+      if (execution.suite.id === "api-response-reading") {
+        // File delivery renders a card instead of an exact summary bubble.
+        // Prove the visible link points to the same independently checked bytes.
+        const proofLink = page.getByRole("link", { name: "Open api-response-proof.txt", exact: true });
+        await expect(proofLink).toBeVisible({ timeout: 30_000 });
+        await expect(proofLink).toHaveAttribute("href", `/api/attachments/${downloadedResponseProof!.attachmentId}/content`);
+      } else if (execution.task.flow === "warm_three_turn") {
         // Prove the persisted user-facing response is visible, independently
         // of the byte-for-byte workspace checks and lease continuity checks.
         expect(finalRunMessage.trim()).not.toBe("");