feat(voyage): add machine-verifiable completion gate to trekexecute

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

tests/commands/trekexecute.test.mjs

@@ -73,3 +73,23 @@ test('trekexecute — SC7: brief_version 2.1 + no phase_signals + no partial →
     `sequencing gate must fire; errors=${JSON.stringify(r.errors)}`,
   );
 });
+
+// --- S38 loop-discipline hardening: completion gate (Step 2) ---
+
+test('trekexecute — machine-verifiable completion gate + stop-signal contract literals present (SC a)', () => {
+  const text = read();
+  assert.ok(text.includes('machine-verifiable completion gate'),
+    'completion-gate literal must be grep-able');
+  assert.ok(text.includes('stop-signal contract'),
+    'stop-signal contract literal must be grep-able');
+});
+
+test('trekexecute — completion gate anchors result:completed to Phase 7.5 audit + DONE-after-check (SC a)', () => {
+  const text = read();
+  const gateIdx = text.indexOf('machine-verifiable completion gate');
+  assert.ok(gateIdx >= 0, 'gate literal missing');
+  const section = text.slice(gateIdx, gateIdx + 1400);
+  assert.match(section, /Phase 7\.5/, 'gate must name Phase 7.5 as the objective predicate');
+  assert.match(section, /DONE/, 'gate must reference the DONE stop-signal token');
+  assert.match(section, /emitted AFTER/, 'gate must require DONE emitted AFTER the audit ran');
+});