fix: address code review - add defensive guard, boundary test, integration comment

Author: Astro-Han

src/drift.test.ts

@@ -46,8 +46,8 @@ describe('detectDrift', () => {
     expect(report.fields[0].emptyRate).toBe(0.8);
   });
 
-  it('does not detect drift below threshold', () => {
-    // 3 out of 5 = 60%, below default 0.8
+  it('does not detect drift below threshold (60%)', () => {
+    // 3 out of 5 = 60%, well below default 0.8
     const rows = [
       { title: '' },
       { title: '' },
@@ -59,6 +59,18 @@ describe('detectDrift', () => {
     expect(report.hasDrift).toBe(false);
   });
 
+  it('does not detect drift just below threshold (75%)', () => {
+    // 3 out of 4 = 75%, just under 0.8
+    const rows = [
+      { title: '' },
+      { title: '' },
+      { title: '' },
+      { title: 'x' },
+    ];
+    const report = detectDrift(rows, ['title'], 0.8);
+    expect(report.hasDrift).toBe(false);
+  });
+
   it('detects multiple fields drifting', () => {
     const rows = [
       { title: '', author: '', score: 10 },

src/drift.ts

@@ -61,6 +61,7 @@ export function detectDrift(
  * Wrapped in chalk.yellow. No trailing newline (console.error adds it).
  */
 export function formatDriftWarning(report: DriftReport, commandName: string): string {
+  if (!report.fields.length) return '';
   const lines = [chalk.yellow(`\u26a0 Schema drift detected (${commandName}):`)];
   for (const f of report.fields) {
     const pct = Math.round(f.emptyRate * 100);

src/main.ts

@@ -206,6 +206,7 @@ for (const [, cmd] of registry) {
       if (actionOpts.verbose && (!result || (Array.isArray(result) && result.length === 0))) {
         console.error(chalk.yellow(`[Verbose] Warning: Command returned an empty result. If the website structural API changed or requires authentication, check the network or update the adapter.`));
       }
+      // Schema drift: warn if columns are suspiciously empty (non-breaking, stderr only)
       if (Array.isArray(result) && result.length > 0 && cmd.columns?.length) {
         const report = detectDrift(result, cmd.columns);
         if (report.hasDrift) {