diff --git a/python/scenario/_tracing/setup.py b/python/scenario/_tracing/setup.py
index 2b9d4ee00..f4f7fd638 100644
--- a/python/scenario/_tracing/setup.py
+++ b/python/scenario/_tracing/setup.py
@@ -10,7 +10,7 @@
 
 import logging
 import os
-from typing import List, Optional, Sequence
+from typing import List, Optional, Protocol, Sequence, cast
 
 from opentelemetry import trace
 from opentelemetry.sdk.trace import TracerProvider, SpanProcessor
@@ -25,6 +25,10 @@
 _initialized = False
 
 
+class _SpanProcessorProvider(Protocol):
+    def add_span_processor(self, span_processor: SpanProcessor) -> None: ...
+
+
 def setup_scenario_tracing(
     *,
     span_filter: Optional[SpanFilter] = None,
@@ -88,7 +92,7 @@ def ensure_tracing_initialized(observability: Optional[dict] = None) -> None:
     _initialized = True
 
 
-def _get_concrete_provider(provider) -> Optional[TracerProvider]:
+def _get_concrete_provider(provider) -> Optional[_SpanProcessorProvider]:
     """Returns the concrete TracerProvider if one exists.
 
     Checks the provider itself and one level of delegation
@@ -97,6 +101,12 @@ def _get_concrete_provider(provider) -> Optional[TracerProvider]:
     if isinstance(provider, TracerProvider):
         return provider
 
+    # OpenTelemetry's public provider interface does not require an SDK
+    # TracerProvider subclass. Providers such as Temporal's replay-safe wrapper
+    # expose the processor hook directly and are safe to configure in place.
+    if callable(getattr(provider, "add_span_processor", None)):
+        return cast(_SpanProcessorProvider, provider)
+
     # Check delegation pattern
     delegate = None
     if hasattr(provider, "get_delegate"):
@@ -122,16 +132,17 @@ def _do_setup(
     concrete = _get_concrete_provider(existing_provider)
 
     if concrete is not None:
-        _attach_to_existing(concrete, span_filter, span_processors, trace_exporter)
+        _attach_to_existing(concrete, span_filter, span_processors, trace_exporter, instrumentors)
     else:
         _full_setup(span_filter, span_processors, trace_exporter, instrumentors)
 
 
 def _attach_to_existing(
-    provider: TracerProvider,
+    provider: _SpanProcessorProvider,
     span_filter: Optional[SpanFilter],
     span_processors: Optional[List[SpanProcessor]],
     trace_exporter: Optional[SpanExporter],
+    instrumentors: Optional[Sequence],
 ) -> None:
     """Attach processors to an existing TracerProvider."""
     provider.add_span_processor(judge_span_collector)
@@ -150,6 +161,10 @@ def _attach_to_existing(
     # Add LangWatch exporter
     _add_langwatch_exporter(provider, span_filter)
 
+    if instrumentors:
+        for instrumentor in instrumentors:
+            instrumentor.instrument(tracer_provider=provider)
+
 
 def _full_setup(
     span_filter: Optional[SpanFilter],
diff --git a/python/tests/test_tracing_setup.py b/python/tests/test_tracing_setup.py
index 69339dacd..dae3e2857 100644
--- a/python/tests/test_tracing_setup.py
+++ b/python/tests/test_tracing_setup.py
@@ -8,6 +8,7 @@
     setup_scenario_tracing,
     ensure_tracing_initialized,
     _get_concrete_provider,
+    _do_setup,
     _reset_tracing_for_tests,
 )
 
@@ -92,6 +93,17 @@ def test_returns_tracer_provider_directly(self) -> None:
 
         assert result is provider
 
+    def test_returns_public_provider_with_span_processor_support(self) -> None:
+        class PublicProvider:
+            def add_span_processor(self, span_processor) -> None:
+                del span_processor
+
+        provider = PublicProvider()
+
+        result = _get_concrete_provider(provider)
+
+        assert result is provider
+
     def test_returns_delegate_from_get_delegate(self) -> None:
         concrete = TracerProvider()
 
@@ -129,6 +141,20 @@ class FakeProxy:
         assert result is None
 
 
+def test_instruments_an_existing_public_provider() -> None:
+    class PublicProvider:
+        def add_span_processor(self, span_processor) -> None:
+            del span_processor
+
+    provider = PublicProvider()
+    instrumentor = MagicMock()
+
+    with patch("scenario._tracing.setup.trace.get_tracer_provider", return_value=provider):
+        _do_setup(instrumentors=[instrumentor])
+
+    instrumentor.instrument.assert_called_once_with(tracer_provider=provider)
+
+
 class TestResetTracingForTests:
     """Tests for _reset_tracing_for_tests."""