fix(claude_sdk,conversations,rotation): context size from the last api call, new-day text by rotation reason

tests/test_rotation.py

@@ -100,7 +100,7 @@ async def test_rotation_order_handout_close_marks_moves_and_new_day(
         return f"напиши хендаут за {ctx.day}"
 
     world.conversations._texts = ConversationTexts(  # noqa: SLF001
-        handout=handout, new_day="Новый день {day}."
+        handout=handout, new_day=lambda ctx: f"Новый день {ctx.day} ({ctx.reason})."
     )
     old = await world.conversations.spawn(kind="master", agent="a", seed="clean")
     old = await age(world, old, datetime(2026, 8, 27, 9, 0, tzinfo=UTC))
@@ -140,7 +140,7 @@ async def test_rotation_order_handout_close_marks_moves_and_new_day(
     prompt = new_client.prompts[0]
     assert prompt.startswith("[сид: morning] master")
     assert "[инжект: ротация" in prompt
-    assert "Новый день" in prompt
+    assert "Новый день 20" in prompt and "(ночь)" in prompt
     assert "переехало из старого мастера: 1" in prompt
     moved = await world.conversations.queue.pending(new.id)
     assert [(i.priority, i.text) for i in moved] == [("normal", "later")]
@@ -172,3 +172,29 @@ async def test_due_uses_last_usage_row_for_context_size(world: World) -> None:
     rotation = Rotation(world.conversations, RotationPolicy(max_context_tokens=5))
     (pair,) = await rotation.due()
     assert pair[0].id == conv.id and pair[1] == "транскрипт"
+
+
+def test_context_of_prefers_last_call_and_averages_old_rows() -> None:
+    from beaver_gateway.core.conversations import context_of
+    from beaver_gateway.storage.models import Usage
+
+    fresh = Usage(
+        agent_name="a",
+        model="m",
+        input_tokens=12,
+        cache_read_tokens=142_984,
+        cache_creation_tokens=29_584,
+        num_turns=6,
+        context_tokens=29_000,
+    )
+    assert context_of(fresh) == 29_000
+    old = Usage(
+        agent_name="a",
+        model="m",
+        input_tokens=12,
+        cache_read_tokens=142_984,
+        cache_creation_tokens=29_584,
+        num_turns=6,
+    )
+    assert context_of(old) == 28_763
+    assert context_of(None) == 0