From 84115038b344527ed482fb0ef447e9e333180a1d Mon Sep 17 00:00:00 2001
From: Arvid Berndtsson <103070833+arvid-berndtsson@users.noreply.github.com>
Date: Sat, 3 Oct 2026 12:48:02 +0200
Subject: [PATCH] fix: sanitize terminal controls in agent output

---
 src/output.test.ts | 29 +++++++++++++++++++++++++++++
 src/output.ts      |  6 +++++-
 2 files changed, 34 insertions(+), 1 deletion(-)

diff --git a/src/output.test.ts b/src/output.test.ts
index 64b1f95..94c46c6 100644
--- a/src/output.test.ts
+++ b/src/output.test.ts
@@ -25,4 +25,33 @@ describe("printResponse", () => {
       totalCount: 1,
     });
   });
+
+  it("removes terminal control bytes from agent-mode output", () => {
+    let out = "";
+    printResponse(
+      { message: "\u001b]0;PWNED\u0007\u001b[31mred\u001b[0m" },
+      { pretty: false, agentMode: true },
+      (s) => {
+        out += s;
+      },
+    );
+
+    assert.equal(/[\u0000-\u001f\u007f-\u009f]/u.test(out.slice(0, -1)), false);
+    assert.match(out, /message: ".*PWNED.*red/);
+    assert.equal(out.endsWith("\n"), true);
+  });
+
+  it("keeps TOON structural newlines and escaped string controls", () => {
+    let out = "";
+    printResponse(
+      { message: "line1\nline2\r\n\tindented" },
+      { pretty: false, agentMode: true },
+      (s) => {
+        out += s;
+      },
+    );
+
+    assert.equal(out.split("\n").length, 2);
+    assert.match(out, /line1\\nline2\\r\\n\\tindented/);
+  });
 });
diff --git a/src/output.ts b/src/output.ts
index 9f77f2b..54f57c4 100644
--- a/src/output.ts
+++ b/src/output.ts
@@ -39,6 +39,10 @@ function unwrapResultsData(value: unknown): unknown {
   return normalized;
 }
 
+function sanitizeTerminalControls(value: string): string {
+  return value.replace(/[\u0000-\u0008\u000b\u000c\u000e-\u001f\u007f-\u009f]/g, "");
+}
+
 export function printResponse(
   value: unknown,
   options: OutputOptions,
@@ -52,7 +56,7 @@ export function printResponse(
   const normalized = unwrapResultsData(value);
 
   if (agentModeEnabled(options.agentMode)) {
-    write(`${encode(normalized)}\n`);
+    write(`${sanitizeTerminalControls(encode(normalized))}\n`);
     return;
   }