From 5d73b83a2162913236e2f577dc19259c09bc6745 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=E5=A2=A8=E7=B6=A0BG?= <s5460703@gmail.com>
Date: Fri, 31 Jul 2026 22:51:09 +0800
Subject: [PATCH] fix(eve): report evals without agent output to Braintrust
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Signed-off-by: 墨綠BG <s5460703@gmail.com>
---
 .changeset/braintrust-empty-output.md         |  5 ++++
 .../evals/runner/reporters/braintrust.test.ts | 28 +++++++++++++++++++
 .../src/evals/runner/reporters/braintrust.ts  |  2 +-
 3 files changed, 34 insertions(+), 1 deletion(-)
 create mode 100644 .changeset/braintrust-empty-output.md

diff --git a/.changeset/braintrust-empty-output.md b/.changeset/braintrust-empty-output.md
new file mode 100644
index 000000000..9006e1f2b
--- /dev/null
+++ b/.changeset/braintrust-empty-output.md
@@ -0,0 +1,5 @@
+---
+"eve": patch
+---
+
+Prevent Braintrust reporting from stopping an eval run when a case produces no agent output.
diff --git a/packages/eve/src/evals/runner/reporters/braintrust.test.ts b/packages/eve/src/evals/runner/reporters/braintrust.test.ts
index a70421659..0dcf6ba9a 100644
--- a/packages/eve/src/evals/runner/reporters/braintrust.test.ts
+++ b/packages/eve/src/evals/runner/reporters/braintrust.test.ts
@@ -199,4 +199,32 @@ describe("Braintrust", () => {
       }),
     );
   });
+
+  it("logs evals that produce no agent output", async () => {
+    const reporter = Braintrust(makeConfig());
+    await reporter.onRunStart([makeEval()], makeTarget());
+
+    braintrustMocks.log.mockImplementationOnce((event: { output?: unknown }) => {
+      if (event.output === null || event.output === undefined) {
+        throw new Error("output must be specified");
+      }
+    });
+
+    const result = makeEvalResult();
+    const resultWithoutOutput: EveEvalResult = {
+      ...result,
+      result: {
+        ...result.result,
+        output: null,
+        finalMessage: null,
+      },
+    };
+
+    expect(() => reporter.onEvalComplete(resultWithoutOutput)).not.toThrow();
+    expect(braintrustMocks.log).toHaveBeenCalledWith(
+      expect.objectContaining({
+        output: "",
+      }),
+    );
+  });
 });
diff --git a/packages/eve/src/evals/runner/reporters/braintrust.ts b/packages/eve/src/evals/runner/reporters/braintrust.ts
index 2b611cde6..9b46ab6bd 100644
--- a/packages/eve/src/evals/runner/reporters/braintrust.ts
+++ b/packages/eve/src/evals/runner/reporters/braintrust.ts
@@ -175,7 +175,7 @@ class BraintrustReporter implements EvalReporter {
     this.#experiment.log({
       id: result.id,
       input: evaluation?.description ?? "",
-      output: result.result.output,
+      output: result.result.output ?? "",
       error: result.error ?? undefined,
       scores,
       metadata,