refactor(providers): define typed usage contract

tests/cli/test_restart_command.py

@@ -12,7 +12,7 @@ from unittest.mock import AsyncMock, MagicMock, patch
 import pytest
 
 from nanobot.bus.events import InboundMessage
-from nanobot.providers.base import LLMResponse
+from nanobot.providers.base import LLMResponse, LLMUsage
 
 
 def _make_loop():
@@ -238,7 +238,7 @@ class TestRestartCommand:
         session.get_history.return_value = [{"role": "user"}] * 3
         loop.sessions.get_or_create.return_value = session
         loop._start_time = time.time() - 125
-        loop._last_usage = {"prompt_tokens": 0, "completion_tokens": 0}
+        loop._last_usage = LLMUsage.reported(input_tokens=0, output_tokens=0)
         loop.consolidator.estimate_session_prompt_tokens = MagicMock(
             return_value=(20500, "tiktoken")
         )
@@ -305,18 +305,15 @@ class TestRestartCommand:
             lambda _message: 7,
         )
         loop.provider.chat_with_retry = AsyncMock(side_effect=[
-            LLMResponse(content="first", usage={"prompt_tokens": 9, "completion_tokens": 4}),
-            LLMResponse(content="second", usage={}),
+            LLMResponse(content="first", usage=LLMUsage.reported(input_tokens=9, output_tokens=4)),
+            LLMResponse(content="second", usage=None),
         ])
 
         await loop._run_agent_loop([], runtime=loop.llm_runtime())
-        assert loop._last_usage["prompt_tokens"] == 9
-        assert loop._last_usage["completion_tokens"] == 4
+        assert loop._last_usage == LLMUsage.reported(input_tokens=9, output_tokens=4)
 
         await loop._run_agent_loop([], runtime=loop.llm_runtime())
-        assert loop._last_usage["prompt_tokens"] == 123
-        assert loop._last_usage["completion_tokens"] == 7
-        assert loop._last_usage["estimated_tokens"] == 130
+        assert loop._last_usage == LLMUsage.estimated(input_tokens=123, output_tokens=7)
 
     @pytest.mark.asyncio
     async def test_status_falls_back_to_last_usage_when_context_estimate_missing(self):
@@ -324,7 +321,7 @@ class TestRestartCommand:
         session = MagicMock()
         session.get_history.return_value = [{"role": "user"}]
         loop.sessions.get_or_create.return_value = session
-        loop._last_usage = {"prompt_tokens": 1200, "completion_tokens": 34}
+        loop._last_usage = LLMUsage.reported(input_tokens=1200, output_tokens=34)
         loop.consolidator.estimate_session_prompt_tokens = MagicMock(
             return_value=(0, "none")
         )