Keep tool output out of span errors and fix trace status and listing

Tool results, denial comments and tool exception text now reach a span only
as a capture-gated preview; span.error is a fixed message, since it is
stored and exported regardless of content settings. A turn whose stream
yields an error event is recorded as failed. Search traces are listed by a
query copied into the small summary column, so the Logs timeline never
reads the spans JSONB. Adds GraphRAG span tests.

tests/tracing/test_trace.py

@@ -353,3 +353,22 @@ class TestOutcome:
         trace.outcome = "paused"
         trace.finish(status="error")
         assert trace.status == "error"
+
+
+class TestRecordQuery:
+    def test_first_span_query_is_copied_into_summary(self):
+        trace = tracing.start_trace(source="search")
+        with tracing.activate(trace):
+            with tracing.span(tracing.KIND_RETRIEVAL, "retrieval") as s:
+                s.preview("query", "how do I deploy")
+        trace.finish()
+        assert trace.to_record()["summary"]["query"] == "how do I deploy"
+
+    def test_query_is_dropped_when_content_is_blocked(self):
+        trace = tracing.start_trace(source="search")
+        with tracing.activate(trace):
+            with tracing.span(tracing.KIND_RETRIEVAL, "retrieval") as s:
+                s.preview("query", "leaky")
+            tracing.mark_content_blocked()
+        trace.finish()
+        assert "query" not in trace.to_record()["summary"]