refactor(providers): define typed usage contract

tests/agent/tools/test_self_tool.py

@@ -15,6 +15,7 @@ from nanobot.agent.tools.self import MyTool
 from nanobot.agent.tools.shell import ExecToolConfig
 from nanobot.agent.tools.web import WebSearchConfig, WebToolsConfig
 from nanobot.config.schema import ModelPresetConfig
+from nanobot.providers.base import LLMUsage
 
 # ---------------------------------------------------------------------------
 # Helpers
@@ -31,7 +32,7 @@ def _make_mock_loop(**overrides):
     loop._start_time = 1000.0
     loop.exec_config = ExecToolConfig()
     loop.channels_config = MagicMock()
-    loop._last_usage = {"prompt_tokens": 100, "completion_tokens": 50}
+    loop._last_usage = LLMUsage.reported(input_tokens=100, output_tokens=50)
     loop.last_usage = loop._last_usage
     loop._current_iteration = 0
     loop.current_iteration = loop._current_iteration
@@ -163,9 +164,9 @@ class TestInspectPathNavigation:
     @pytest.mark.asyncio
     async def test_inspect_dict_key_via_dotpath(self):
         loop = _make_mock_loop()
-        loop._last_usage = {"prompt_tokens": 100, "completion_tokens": 50}
+        loop._last_usage = LLMUsage.reported(input_tokens=100, output_tokens=50)
         tool = _make_tool(loop=loop)
-        result = await tool.execute(action="check", key="_last_usage.prompt_tokens")
+        result = await tool.execute(action="check", key="_last_usage.input_tokens")
         assert "100" in result
 
     @pytest.mark.asyncio
@@ -624,7 +625,7 @@ class TestSubagentStatusFormatting:
                 {"name": "grep", "status": "ok", "detail": "searched ERROR"},
                 {"name": "exec", "status": "error", "detail": "timeout"},
             ],
-            usage={"prompt_tokens": 4500, "completion_tokens": 1200},
+            usage=LLMUsage.reported(input_tokens=4500, output_tokens=1200),
         )
         result = MyTool._format_value(status)
         assert "abc12345" in result
@@ -698,14 +699,14 @@ class TestSubagentHookStatus:
             iteration=5,
             messages=[],
             tool_events=[{"name": "read_file", "status": "ok", "detail": "ok"}],
-            usage={"prompt_tokens": 100, "completion_tokens": 50},
+            usage=LLMUsage.reported(input_tokens=100, output_tokens=50),
         )
         await hook.after_iteration(context)
 
         assert status.iteration == 5
         assert len(status.tool_events) == 1
         assert status.tool_events[0]["name"] == "read_file"
-        assert status.usage == {"prompt_tokens": 100, "completion_tokens": 50}
+        assert status.usage == LLMUsage.reported(input_tokens=100, output_tokens=50)
 
     @pytest.mark.asyncio
     async def test_after_iteration_with_error(self):
@@ -821,7 +822,7 @@ class TestInspectTaskStatuses:
                 phase="awaiting_tools",
                 iteration=2,
                 tool_events=[{"name": "read_file", "status": "ok", "detail": "ok"}],
-                usage={"prompt_tokens": 500, "completion_tokens": 100},
+                usage=LLMUsage.reported(input_tokens=500, output_tokens=100),
             ),
         }
         tool = _make_tool(loop=loop)
@@ -1127,12 +1128,12 @@ class TestLastUsageInSummary:
         tool = _make_tool()
         result = await tool.execute(action="check")
         assert "_last_usage" in result
-        assert "prompt_tokens" in result
+        assert "input_tokens" in result
 
     @pytest.mark.asyncio
     async def test_last_usage_not_shown_when_empty(self):
         loop = _make_mock_loop()
-        loop._last_usage = {}
+        loop._last_usage = None
         loop.last_usage = loop._last_usage
         tool = _make_tool(loop=loop)
         result = await tool.execute(action="check")

tests/agent/tools/test_subagent_tools.py

@@ -456,7 +456,7 @@ async def test_agent_loop_syncs_updated_max_iterations_before_run(tmp_path):
             error=None,
             tool_events=[],
             messages=[],
-            usage={},
+            usage=None,
             had_injections=False,
             tools_used=[],
         )
@@ -501,7 +501,7 @@ async def test_drain_pending_blocks_while_subagents_running(tmp_path):
             error=None,
             tool_events=[],
             messages=[],
-            usage={},
+            usage=None,
             had_injections=False,
             tools_used=[],
             provider_state=None,
@@ -587,7 +587,7 @@ async def test_drain_pending_no_block_when_no_subagents(tmp_path):
             error=None,
             tool_events=[],
             messages=[],
-            usage={},
+            usage=None,
             had_injections=False,
             tools_used=[],
             provider_state=None,
@@ -637,7 +637,7 @@ async def test_drain_pending_timeout(tmp_path):
             error=None,
             tool_events=[],
             messages=[],
-            usage={},
+            usage=None,
             had_injections=False,
             tools_used=[],
             provider_state=None,