fix(beam): date a session by its first non-null time_anchor

scripts/beam/beam_ingestion.py

@@ -80,6 +80,19 @@ def parse_time_anchor(time_anchor_str):
     return parse_beam_time(time_anchor_str)
 
 
+def session_time_anchor(messages, default="January-01-2024"):
+    """Return the first non-empty ``time_anchor`` in a session, else ``default``.
+
+    BEAM-10M conversation 7 session 0 opens with null anchors; its first
+    anchor (index 244) is March-05-2020. Every other 10M session starts with
+    an anchor, so they keep the date of their first message.
+    """
+    for msg in messages:
+        if isinstance(msg, dict) and msg.get("time_anchor"):
+            return msg["time_anchor"]
+    return default
+
+
 _BEAM_RETAIN_MISSION = (
     "Extract ALL factual claims the user makes about themselves, their project, "
     "and their experience — including NEGATIVE statements (e.g. 'I have never done X', "
@@ -172,8 +185,7 @@ def ingest_conversation(conv, version, frame, success_records, f, clear=False):
         if not session:
             continue
 
-        first_msg = session[0]
-        session_date = parse_time_anchor(first_msg.get("time_anchor", "January-01-2024"))
+        session_date = parse_time_anchor(session_time_anchor(session))
         session_id = f"{user_id}_session_{sess_idx}"
 
         try:

scripts/beam/beam_streaming.py

@@ -37,6 +37,7 @@
     ingest_session,
     load_beam_data,
     parse_time_anchor,
+    session_time_anchor,
 )
 from beam.beam_search import parse_probing_questions  # noqa: E402
 from beam.beam_common import (  # noqa: E402
@@ -155,9 +156,7 @@ def build_graphiti_session_chunks(
 ) -> list[BeamGraphitiChunk]:
     conv_id = str(conv["conversation_id"])
     scale = conv.get("_scale", "unknown")
-    session_date = parse_time_anchor(
-        messages[0].get("time_anchor", "January-01-2024") if messages else "January-01-2024"
-    )
+    session_date = parse_time_anchor(session_time_anchor(messages))
     timestamp = session_date.isoformat()
 
     body_lines = [
@@ -310,7 +309,7 @@ def add_conversation_per_session(
         session_chars = sum(len(msg.get("content", "")) for msg in messages)
         total_messages += len(messages)
         total_chars += session_chars
-        session_date = parse_time_anchor(messages[0].get("time_anchor", "January-01-2024"))
+        session_date = parse_time_anchor(session_time_anchor(messages))
         session_id = f"{user_id}_session_{session_idx}"
 
         if checkpoint_id in added_sessions:

scripts/tests/unit/test_beam_time_anchor.py

@@ -0,0 +1,20 @@
+"""Session date selection for BEAM ingestion (null leading time_anchor)."""
+
+from datetime import datetime, timezone
+
+from beam.beam_ingestion import parse_time_anchor, session_time_anchor
+
+
+def test_first_message_anchor_is_used():
+    msgs = [{"time_anchor": "March-15-2024"}, {"time_anchor": "April-01-2024"}]
+    assert session_time_anchor(msgs) == "March-15-2024"
+
+
+def test_null_leading_anchor_uses_first_non_null():
+    msgs = [{"time_anchor": None}] * 3 + [{"time_anchor": "March-05-2020"}, {"time_anchor": "June-01-2020"}]
+    assert parse_time_anchor(session_time_anchor(msgs)) == datetime(2020, 3, 5, tzinfo=timezone.utc)
+
+
+def test_missing_or_empty_anchors_fall_back_to_default():
+    assert session_time_anchor([{"role": "user"}, {"time_anchor": ""}]) == "January-01-2024"
+    assert session_time_anchor([]) == "January-01-2024"