**refactor(dynamic): introduce NATS protocol emulator with publish/deliver support, enhance endpoint handling, and extend SDK compatibility for Go and Python**

tests/dynamic_fixtures/migration/django_ops/vuln.py

@@ -0,0 +1,19 @@
+"""Phase 21 — Django Migration.operations runtime fixture."""
+_NYX_ADAPTER_MARKER = "from django.db import migrations"
+
+import os
+
+
+class _RunSQL:
+    def __init__(self, sql):
+        self.sql = sql
+
+
+class Migration:
+    operations = [
+        _RunSQL(
+            "CREATE INDEX idx_"
+            + (os.environ.get("NYX_PAYLOAD") or "users")
+            + " ON users(name)"
+        )
+    ]

tests/message_handler_corpus.rs

@@ -395,6 +395,27 @@ fn message_handler_remaining_brokers_try_http_emulators_before_loopback() {
     }
 }
 
+#[test]
+fn message_handler_nats_go_tries_real_client_before_fallbacks() {
+    let spec = make_spec_with_adapter(
+        Lang::Go,
+        "events",
+        "OnMessage",
+        entry_file("nats_go"),
+        "nats-go",
+    );
+    let h = lang::emit(&spec).expect("emit ok");
+    assert!(h.source.contains("nyxTryRealNats"));
+    assert!(h.source.contains("github.com/nats-io/nats.go"));
+    assert!(h.source.contains("nats.Connect"));
+    assert!(h.source.contains("nc.Subscribe"));
+    assert!(h.source.contains("nc.Publish"));
+    assert!(
+        h.source.find("nyxTryRealNats").unwrap() < h.source.find("nyxFetchHttpBroker").unwrap(),
+        "nats-go should try the real protocol client before the HTTP fallback"
+    );
+}
+
 // ── Framework-adapter assertions ──────────────────────────────────────────────
 
 fn ts_language_for(lang: Lang) -> tree_sitter::Language {

tests/phase21_corpus.rs

@@ -911,6 +911,9 @@ fn migration_python_harness_carries_sentinel_and_handler() {
     assert!(h.source.contains("__nyx_stub_sql_record"));
     assert!(h.source.contains("MigrationContext.configure"));
     assert!(h.source.contains("NYX_SQL_ENDPOINT"));
+    assert!(h.source.contains("def create_table"));
+    assert!(h.source.contains("def add_column"));
+    assert!(h.source.contains("_nyx_run_django_migration_operations"));
 }
 
 #[test]
@@ -1582,6 +1585,27 @@ fn phase_21_vuln_fixtures_confirm_via_run_spec() {
     }
 }
 
+#[test]
+fn migration_django_operations_class_confirms_via_run_spec() {
+    let case = RunSpecCase {
+        name: "migration-django-operations",
+        lang: Lang::Python,
+        kind: migration_kind,
+        entry_name: "Migration",
+        fixture_dir: "tests/dynamic_fixtures/migration/django_ops",
+        vuln_file: "vuln.py",
+        benign_file: "vuln.py",
+        cap: Cap::SQL_QUERY,
+    };
+    let Some(outcome) = run_phase21_case(case, case.vuln_file) else {
+        return;
+    };
+    assert!(
+        outcome.triggered_by.is_some(),
+        "Django Migration.operations fixture must Confirm via run_spec; got {outcome:?}",
+    );
+}
+
 #[test]
 fn phase_21_benign_fixtures_do_not_confirm_via_run_spec() {
     for case in RUNSPEC_CASES {