From 1ca871e4339af05b3f38be8b5ce85f866677e5da Mon Sep 17 00:00:00 2001
From: Jeremy Schoemaker <jeremy@shoemoney.com>
Date: Mon, 24 Aug 2026 06:07:48 -0500
Subject: [PATCH] fix(elements): render empty-string tool output in ToolOutput

The ToolOutput guard !(output || errorText) treats every falsy
output as absent, so a tool that legitimately returns an empty
string (reading an empty file, a search with no matches) renders
nothing at all. Hide only when output is nullish and there is no
error text; empty string, 0, and false now render as results.
---
 packages/elements/__tests__/tool.test.tsx | 36 +++++++++++++++++++++++
 packages/elements/src/tool.tsx            |  2 +-
 2 files changed, 37 insertions(+), 1 deletion(-)

diff --git a/packages/elements/__tests__/tool.test.tsx b/packages/elements/__tests__/tool.test.tsx
index a7225762..97279525 100644
--- a/packages/elements/__tests__/tool.test.tsx
+++ b/packages/elements/__tests__/tool.test.tsx
@@ -250,4 +250,40 @@ describe("toolOutput", () => {
     );
     expect(screen.getByText("Result")).toBeInTheDocument();
   });
+
+  it("renders empty-string output", () => {
+    render(
+      <Tool>
+        <ToolOutput errorText={undefined} output="" />
+      </Tool>
+    );
+    expect(screen.getByText("Result")).toBeInTheDocument();
+  });
+
+  it("renders zero output", () => {
+    render(
+      <Tool>
+        <ToolOutput errorText={undefined} output={0} />
+      </Tool>
+    );
+    expect(screen.getByText("Result")).toBeInTheDocument();
+  });
+
+  it("renders false output", () => {
+    render(
+      <Tool>
+        <ToolOutput errorText={undefined} output={false} />
+      </Tool>
+    );
+    expect(screen.getByText("Result")).toBeInTheDocument();
+  });
+
+  it("renders nothing when output is null", () => {
+    const { container } = render(
+      <Tool>
+        <ToolOutput errorText={undefined} output={null} />
+      </Tool>
+    );
+    expect(container.textContent).toBe("");
+  });
 });
diff --git a/packages/elements/src/tool.tsx b/packages/elements/src/tool.tsx
index 9a22010e..77928c85 100644
--- a/packages/elements/src/tool.tsx
+++ b/packages/elements/src/tool.tsx
@@ -138,7 +138,7 @@ export const ToolOutput = ({
   errorText,
   ...props
 }: ToolOutputProps) => {
-  if (!(output || errorText)) {
+  if ((output === undefined || output === null) && !errorText) {
     return null;
   }