diff --git a/changelog.d/fixes/7540-custom-tool-output-images.md b/changelog.d/fixes/7540-custom-tool-output-images.md
new file mode 100644
index 0000000000..c22b4970a9
--- /dev/null
+++ b/changelog.d/fixes/7540-custom-tool-output-images.md
@@ -0,0 +1 @@
+- **fix(sse):** preserve `input_image` parts in array-valued Codex `custom_tool_call_output` payloads instead of rewriting them to invalid `output_text` parts ([#7540](https://github.com/diegosouzapw/OmniRoute/pull/7540)) - thanks @loulanyue
diff --git a/tests/unit/responses-input-sanitizer-name.test.ts b/tests/unit/responses-input-sanitizer-name.test.ts
index 067e233b59..7ac09604c7 100644
--- a/tests/unit/responses-input-sanitizer-name.test.ts
+++ b/tests/unit/responses-input-sanitizer-name.test.ts
@@ -194,3 +194,19 @@ test("normalizes function_call_output image output parts to input_image", () =>
   });
   assert.equal(JSON.stringify(result).includes('"type":"image_url"'), false);
 });
+
+test("preserves custom_tool_call_output input content parts", () => {
+  const items = [
+    {
+      type: "custom_tool_call_output",
+      call_id: "call_2",
+      output: [
+        { type: "input_text", text: "image tool output" },
+        { type: "input_image", image_url: "data:image/png;base64,AAAA" },
+      ],
+    },
+  ];
+  const result = sanitizeResponsesInputItems(items) as Array<Record<string, unknown>>;
+  assert.deepEqual(result[0], items[0]);
+  assert.equal(JSON.stringify(result).includes('"type":"output_text"'), false);
+});