chore(doctor): nit fixes for --check oauth (N3 body=null test + N4 skipped sentinel comment)

scripts/doctor.mjs

@@ -256,6 +256,9 @@ function runOauthOnly(opts, checks, push) {
   }
 
   const fail_count = checks.filter(c => c.level === "FAIL").length;
+  // "skipped" = --check oauth fast path intentionally omits version detection.
+  // AI agents should NOT semver-compare against current_version/latest_version when
+  // either equals "skipped"; the full path provides those fields when needed.
   return {
     schema_version: SCHEMA_VERSION,
     timestamp: new Date().toISOString(),

test-features.mjs

@@ -883,6 +883,17 @@ await asyncTest("doctor --check oauth + service down → fix_service", async ()
   assert.equal(result.fail_count, 1);
 });
 
+await asyncTest("doctor --check oauth + 200 with null body → fix_service", async () => {
+  const result = await runDoctor({
+    checkOnly: "oauth",
+    mockHealth: { status: 200, body: null }
+  });
+  const ids = result.checks.map(c => c.id);
+  assert.deepEqual(ids, ["oauth_ok"]);
+  assert.equal(result.next_action.kind, "fix_service");
+  assert.equal(result.fail_count, 1);
+});
+
 // ── Cleanup ──
 closeDb();