feat: start time travel at inbound request entry via x-td-root-timestamp header

drift/instrumentation/django/middleware.py

@@ -105,6 +105,17 @@ def _handle_replay_request(self, request: HttpRequest, sdk) -> HttpResponse:
             logger.warning("[DJANGO_MIDDLEWARE] No replay_trace_id found in headers, proceeding without span")
             return self.get_response(request)
 
+        # Start time travel as early as possible (inbound request start) to ensure deterministic
+        # behavior for time-dependent code paths, especially cache key generation (e.g. django-cachalot).
+        root_timestamp = headers_lower.get("http_x_td_root_timestamp")
+        if root_timestamp:
+            try:
+                from drift.instrumentation.datetime.instrumentation import start_time_travel
+
+                start_time_travel(root_timestamp, trace_id=replay_trace_id)
+            except Exception as e:
+                logger.debug(f"[DJANGO_MIDDLEWARE] Failed to start time travel from x-td-root-timestamp: {e}")
+
         # Set replay trace context
         replay_token = replay_trace_id_context.set(replay_trace_id)
 

drift/instrumentation/fastapi/instrumentation.py

@@ -131,6 +131,17 @@ async def _handle_replay_request(
 
     logger.debug(f"[FastAPIInstrumentation] Setting replay trace ID: {replay_trace_id}")
 
+    # Start time travel at inbound request start when provided by CLI.
+    # This prevents time drift before the first outbound span is matched (critical for cache keys).
+    root_timestamp = headers_lower.get("x-td-root-timestamp")
+    if root_timestamp:
+        try:
+            from drift.instrumentation.datetime.instrumentation import start_time_travel
+
+            start_time_travel(root_timestamp, trace_id=replay_trace_id)
+        except Exception as e:
+            logger.debug(f"[FastAPIInstrumentation] Failed to start time travel from x-td-root-timestamp: {e}")
+
     # Remove accept-encoding header to prevent compression during replay
     # (responses are stored decompressed, compression would double-compress)
     if "accept-encoding" in headers_lower:

drift/instrumentation/wsgi/handler.py

@@ -142,6 +142,17 @@ def _handle_replay_request(
         # No trace context in REPLAY mode; proceed without span
         return original_wsgi_app(app, environ, start_response)
 
+    # Start time travel at inbound request start when provided by CLI.
+    # This prevents time drift before the first outbound span is matched (critical for cache keys).
+    root_timestamp = headers_lower.get("x-td-root-timestamp")
+    if root_timestamp:
+        try:
+            from drift.instrumentation.datetime.instrumentation import start_time_travel
+
+            start_time_travel(root_timestamp, trace_id=replay_trace_id)
+        except Exception as e:
+            logger.debug(f"[WSGI] Failed to start time travel from x-td-root-timestamp: {e}")
+
     # Set replay trace context
     replay_token = replay_trace_id_context.set(replay_trace_id)