fix: retain standalone integration traces

agent_trace/core/tracer.py

@@ -177,7 +177,8 @@ def start_span(
             The new :class:`Span`.
         """
         parent_span = get_current_span()
-        trace_id = get_current_trace() or uuid.uuid4().hex
+        current_trace_id = get_current_trace()
+        trace_id = current_trace_id or uuid.uuid4().hex
 
         span_data = SpanData(
             trace_id=trace_id,
@@ -193,6 +194,24 @@ def start_span(
         if parent_span:
             parent_span._data.children.append(span_data)
 
+        # Auto-instrumentations call start_span() directly. When there is no
+        # surrounding trace, retain that operation as a one-span trace instead
+        # of silently discarding it when the span ends.
+        standalone_trace = None
+        trace_token = None
+        if parent_span is None and current_trace_id is None:
+            standalone_trace = TraceData(
+                trace_id=trace_id,
+                name=name,
+                start_time=span_data.start_time,
+                root_span=span_data,
+                metadata={},
+            )
+            with self._lock:
+                self._traces[trace_id] = standalone_trace
+            trace_token = set_current_trace(trace_id)
+            self._emit("trace_start", {"trace_id": trace_id, "name": name})
+
         with self._lock:
             self._active_spans[span_data.span_id] = span
 
@@ -218,6 +237,20 @@ def start_span(
             span.end()
             # Restore previous span context using proper reset
             reset_current_span(old_span_token)
+            if standalone_trace is not None:
+                standalone_trace.end_time = span_data.end_time
+                if trace_token is not None:
+                    reset_current_trace(trace_token)
+                self._emit(
+                    "trace_end",
+                    {
+                        "trace_id": trace_id,
+                        "duration_ms": standalone_trace.total_duration_ms,
+                        "total_tokens": standalone_trace.total_tokens,
+                        "total_cost": standalone_trace.total_cost,
+                        "span_count": standalone_trace.span_count,
+                    },
+                )
 
     # ── Internal callbacks ───────────────────────────────────────────
 

tests/test_tracer.py

@@ -27,6 +27,30 @@ def test_nested_spans(self):
         trace = self.tracer.get_all_traces()[-1]
         assert trace.span_count >= 3
 
+    def test_standalone_span_creates_queryable_trace(self):
+        with self.tracer.start_span("openai.gpt-test", SpanKind.LLM) as span:
+            span.set_output({"content": "ok"})
+            with self.tracer.start_span("nested-tool", SpanKind.TOOL):
+                pass
+
+        traces = self.tracer.get_all_traces()
+        assert len(traces) == 1
+        assert traces[0].name == "openai.gpt-test"
+        assert traces[0].root_span is span.data
+        assert traces[0].end_time is not None
+        assert traces[0].span_count == 2
+
+    def test_standalone_span_restores_context_and_records_errors(self):
+        with pytest.raises(RuntimeError, match="provider failed"):
+            with self.tracer.start_span("anthropic.test", SpanKind.LLM):
+                raise RuntimeError("provider failed")
+
+        trace = self.tracer.get_all_traces()[-1]
+        assert trace.root_span.status == SpanStatus.ERROR
+        assert trace.end_time is not None
+        assert get_current_span() is None
+        assert get_current_trace() is None
+
     def test_span_error_handling(self):
         with pytest.raises(ValueError):
             with self.tracer.start_trace("error-test") as root: