diff --git a/drift/core/tracing/td_span_processor.py b/drift/core/tracing/td_span_processor.py
index f2e95b8..ef1e6e7 100644
--- a/drift/core/tracing/td_span_processor.py
+++ b/drift/core/tracing/td_span_processor.py
@@ -171,6 +171,9 @@ def on_end(self, span: ReadableSpan) -> None:
                 replay_trace_id = replay_trace_id_context.get()
                 if replay_trace_id:
                     clean_span.trace_id = replay_trace_id
+                    # Rust path may have prebuilt bytes with the original OTel trace_id.
+                    # Force re-serialization so CLI receives the replay trace_id.
+                    clean_span.proto_span_bytes = None
                 else:
                     logger.error("No replay trace ID found, cannot send inbound span for replay")
                     return
diff --git a/drift/instrumentation/e2e_common/base_runner.py b/drift/instrumentation/e2e_common/base_runner.py
index ee862ff..d13974f 100644
--- a/drift/instrumentation/e2e_common/base_runner.py
+++ b/drift/instrumentation/e2e_common/base_runner.py
@@ -285,7 +285,10 @@ def run_tests(self):
         self.log("Phase 3: Running Tusk Tests", Colors.BLUE)
         self.log("=" * 50, Colors.BLUE)
 
-        env = {"TUSK_ANALYTICS_DISABLED": "1"}
+        env = {
+            "TUSK_ANALYTICS_DISABLED": "1",
+            "TUSK_REQUIRE_INBOUND_REPLAY_SPAN": "1",
+        }
 
         result = self.run_command(
             ["tusk", "run", "--print", "--output-format", "json", "--enable-service-logs"],