Fence unmanaged lifecycle by snapshot time

Co-authored-by: genichin <4282227+genichin@users.noreply.github.com>

tests/application/test_unmanaged_position_lifecycle.py

@@ -140,6 +140,49 @@ def test_in_memory_store_preserves_first_seen_when_resolved_symbol_reappears():
     assert reopened["state"]["evidence_ref"] is None
 
 
+def test_in_memory_store_ignores_stale_resolve_after_newer_observation():
+    store = InMemoryUnmanagedPositionStore()
+    t1 = datetime(2026, 9, 7, 0, 0, tzinfo=UTC)
+    t2 = t1 + timedelta(minutes=1)
+    t3 = t2 + timedelta(minutes=1)
+
+    store.observe(instance_key=INSTANCE, symbol="008110", quantity=3, observed_at=t1)
+    store.observe(instance_key=INSTANCE, symbol="008110", quantity=5, observed_at=t3)
+    resolved = store.resolve_absent(
+        instance_key=INSTANCE,
+        observed_symbols=set(),
+        observed_at=t2,
+    )
+
+    assert resolved == []
+    state = store.get_state(instance_key=INSTANCE, symbol="008110")
+    assert state is not None
+    assert state["lifecycle_state"] == "active"
+    assert state["quantity"] == 5
+    assert store.list_audit(instance_key=INSTANCE, symbol="008110")[-1]["event_type"] == "quantity_changed"
+
+
+def test_in_memory_store_ignores_stale_observation_after_newer_resolution():
+    store = InMemoryUnmanagedPositionStore()
+    t1 = datetime(2026, 9, 7, 0, 0, tzinfo=UTC)
+    t2 = t1 + timedelta(minutes=1)
+    t3 = t2 + timedelta(minutes=1)
+
+    store.observe(instance_key=INSTANCE, symbol="008110", quantity=3, observed_at=t1)
+    store.resolve_absent(instance_key=INSTANCE, observed_symbols=set(), observed_at=t3)
+    stale = store.observe(instance_key=INSTANCE, symbol="008110", quantity=5, observed_at=t2)
+
+    assert stale["transition"] == "stale"
+    state = store.get_state(instance_key=INSTANCE, symbol="008110")
+    assert state is not None
+    assert state["lifecycle_state"] == "resolved"
+    assert state["quantity"] == 3
+    assert [row["event_type"] for row in store.list_audit(instance_key=INSTANCE, symbol="008110")] == [
+        "detected",
+        "resolved",
+    ]
+
+
 def test_reconcile_core_holdings_suppresses_repeated_unmanaged_alarm_spam():
     repo, svc = _wire()
     emitter, transport = _make_emitter()