fix(doctor): keep scrubbed error truncation UTF-16 safe (#102066)

* fix(doctor): keep scrubbed error truncation UTF-16 safe

* test(doctor): assert exact scrubbed error output

---------

Co-authored-by: Peter Steinberger <steipete@gmail.com>

src/flows/doctor-error-message.ts

@@ -1,3 +1,5 @@
+import { truncateUtf16Safe } from "@openclaw/normalization-core/utf16-slice";
+
 // Shared sanitization for doctor/lint/repair errors shown in terminal output.
 const ERR_MESSAGE_MAX_LEN = 256;
 
@@ -14,5 +16,5 @@ export function scrubDoctorErrorMessage(err: unknown): string {
   if (stripped.length <= ERR_MESSAGE_MAX_LEN) {
     return stripped;
   }
-  return `${stripped.slice(0, ERR_MESSAGE_MAX_LEN - 3)}...`;
+  return `${truncateUtf16Safe(stripped, ERR_MESSAGE_MAX_LEN - 3)}...`;
 }

src/flows/doctor-lint-flow.test.ts

@@ -135,6 +135,19 @@ describe("runDoctorLintChecks", () => {
       },
     ]);
   });
+
+  it("keeps truncated thrown error messages UTF-16 safe", async () => {
+    const emoji = "\u{1F600}";
+    const result = await runDoctorLintChecks(ctx, {
+      checks: [
+        check("emoji-boom", async () => {
+          throw new Error(`${"A".repeat(252)}${emoji}${"B".repeat(10)}`);
+        }),
+      ],
+    });
+
+    expect(result.findings[0]?.message).toBe(`health check threw: ${"A".repeat(252)}...`);
+  });
 });
 
 describe("exitCodeFromFindings", () => {