feat(telemetry): include error details for failures (#254)

packages/cli/test/telemetry/scrubber.test.ts

@@ -1,6 +1,6 @@
 import { describe, expect, it } from 'vitest';
 
-import { scrubErrorClass } from '../../src/telemetry/scrubber.js';
+import { formatErrorDetail, scrubErrorClass } from '../../src/telemetry/scrubber.js';
 
 class KtxProjectMissingAbortError extends Error {}
 
@@ -23,3 +23,39 @@ describe('scrubErrorClass', () => {
     expect(scrubErrorClass(null)).toBeUndefined();
   });
 });
+
+describe('formatErrorDetail', () => {
+  it('prefixes a string or numeric .code onto the message', () => {
+    const refused = new Error('connect failed');
+    (refused as { code?: unknown }).code = 'ECONNREFUSED';
+    expect(formatErrorDetail(refused)).toBe('ECONNREFUSED: connect failed');
+
+    const forbidden = new Error('forbidden');
+    (forbidden as { code?: unknown }).code = 403;
+    expect(formatErrorDetail(forbidden)).toBe('403: forbidden');
+  });
+
+  it('uses the bare message when there is no .code', () => {
+    expect(formatErrorDetail(new Error('password authentication failed for user "x"'))).toBe(
+      'password authentication failed for user "x"',
+    );
+  });
+
+  it('accepts non-Error values', () => {
+    expect(formatErrorDetail('boom')).toBe('boom');
+  });
+
+  it('collapses whitespace to a single line', () => {
+    expect(formatErrorDetail(new Error('line one\n   line two'))).toBe('line one line two');
+  });
+
+  it('caps the length at 1000 characters', () => {
+    expect(formatErrorDetail(new Error('x'.repeat(2000)))?.length).toBe(1000);
+  });
+
+  it('returns undefined for empty, null, or undefined input', () => {
+    expect(formatErrorDetail(new Error('   '))).toBeUndefined();
+    expect(formatErrorDetail(null)).toBeUndefined();
+    expect(formatErrorDetail(undefined)).toBeUndefined();
+  });
+});