feat: add configurable log level and token usage tracking (#1301)

* feat: add configurable log level and token usage tracking

- Add `log_level` config to control deerflow module log level, synced
  to LangGraph Server via serve.sh `--server-log-level`
- Add `token_usage.enabled` config with TokenUsageMiddleware that logs
  input/output/total tokens per LLM call from usage_metadata
- Add .omc/ to .gitignore

* fix: use info level for token usage logs since feature has its own toggle

* fix: sort imports to pass lint check

---------

Co-authored-by: greatmengqi <chenmengqi.0376@bytedance.com>
Co-authored-by: Willem Jiang <willem.jiang@gmail.com>

.gitignore

@@ -1,5 +1,7 @@
 # DeerFlow docker image cache
 docker/.cache/
+# oh-my-claudecode state
+.omc/
 # OS generated files
 .DS_Store
 *.local

backend/packages/harness/deerflow/agents/lead_agent/agent.py

@@ -11,6 +11,7 @@ from deerflow.agents.middlewares.memory_middleware import MemoryMiddleware
 from deerflow.agents.middlewares.subagent_limit_middleware import SubagentLimitMiddleware
 from deerflow.agents.middlewares.title_middleware import TitleMiddleware
 from deerflow.agents.middlewares.todo_middleware import TodoMiddleware
+from deerflow.agents.middlewares.token_usage_middleware import TokenUsageMiddleware
 from deerflow.agents.middlewares.tool_error_handling_middleware import build_lead_runtime_middlewares
 from deerflow.agents.middlewares.view_image_middleware import ViewImageMiddleware
 from deerflow.agents.thread_state import ThreadState
@@ -227,6 +228,10 @@ def _build_middlewares(config: RunnableConfig, model_name: str | None, agent_nam
     if todo_list_middleware is not None:
         middlewares.append(todo_list_middleware)
 
+    # Add TokenUsageMiddleware when token_usage tracking is enabled
+    if get_app_config().token_usage.enabled:
+        middlewares.append(TokenUsageMiddleware())
+
     # Add TitleMiddleware
     middlewares.append(TitleMiddleware())
 
@@ -243,6 +248,7 @@ def _build_middlewares(config: RunnableConfig, model_name: str | None, agent_nam
     # Add DeferredToolFilterMiddleware to hide deferred tool schemas from model binding
     if app_config.tool_search.enabled:
         from deerflow.agents.middlewares.deferred_tool_filter_middleware import DeferredToolFilterMiddleware
+
         middlewares.append(DeferredToolFilterMiddleware())
 
     # Add SubagentLimitMiddleware to truncate excess parallel task calls

backend/packages/harness/deerflow/agents/middlewares/token_usage_middleware.py

@@ -0,0 +1,37 @@
+"""Middleware for logging LLM token usage."""
+
+import logging
+from typing import override
+
+from langchain.agents import AgentState
+from langchain.agents.middleware import AgentMiddleware
+from langgraph.runtime import Runtime
+
+logger = logging.getLogger(__name__)
+
+
+class TokenUsageMiddleware(AgentMiddleware):
+    """Logs token usage from model response usage_metadata."""
+
+    @override
+    def after_model(self, state: AgentState, runtime: Runtime) -> dict | None:
+        return self._log_usage(state)
+
+    @override
+    async def aafter_model(self, state: AgentState, runtime: Runtime) -> dict | None:
+        return self._log_usage(state)
+
+    def _log_usage(self, state: AgentState) -> None:
+        messages = state.get("messages", [])
+        if not messages:
+            return None
+        last = messages[-1]
+        usage = getattr(last, "usage_metadata", None)
+        if usage:
+            logger.info(
+                "LLM token usage: input=%s output=%s total=%s",
+                usage.get("input_tokens", "?"),
+                usage.get("output_tokens", "?"),
+                usage.get("total_tokens", "?"),
+            )
+        return None

backend/packages/harness/deerflow/config/app_config.py

@@ -17,6 +17,7 @@ from deerflow.config.skills_config import SkillsConfig
 from deerflow.config.subagents_config import load_subagents_config_from_dict
 from deerflow.config.summarization_config import load_summarization_config_from_dict
 from deerflow.config.title_config import load_title_config_from_dict
+from deerflow.config.token_usage_config import TokenUsageConfig
 from deerflow.config.tool_config import ToolConfig, ToolGroupConfig
 from deerflow.config.tool_search_config import ToolSearchConfig, load_tool_search_config_from_dict
 
@@ -28,6 +29,8 @@ logger = logging.getLogger(__name__)
 class AppConfig(BaseModel):
     """Config for the DeerFlow application"""
 
+    log_level: str = Field(default="info", description="Logging level for deerflow modules (debug/info/warning/error)")
+    token_usage: TokenUsageConfig = Field(default_factory=TokenUsageConfig, description="Token usage tracking configuration")
     models: list[ModelConfig] = Field(default_factory=list, description="Available models")
     sandbox: SandboxConfig = Field(description="Sandbox configuration")
     tools: list[ToolConfig] = Field(default_factory=list, description="Available tools")
@@ -163,8 +166,7 @@ class AppConfig(BaseModel):
 
         if user_version < example_version:
             logger.warning(
-                "Your config.yaml (version %d) is outdated — the latest version is %d. "
-                "Run `make config-upgrade` to merge new fields into your config.",
+                "Your config.yaml (version %d) is outdated — the latest version is %d. Run `make config-upgrade` to merge new fields into your config.",
                 user_version,
                 example_version,
             )

backend/packages/harness/deerflow/config/token_usage_config.py

@@ -0,0 +1,7 @@
+from pydantic import BaseModel, Field
+
+
+class TokenUsageConfig(BaseModel):
+    """Configuration for token usage tracking."""
+
+    enabled: bool = Field(default=False, description="Enable token usage tracking middleware")

config.example.yaml

@@ -14,6 +14,20 @@
 # Run `make config-upgrade` to merge new fields into your local config.yaml.
 config_version: 3
 
+# ============================================================================
+# Logging
+# ============================================================================
+# Log level for deerflow modules (debug/info/warning/error)
+log_level: info
+
+# ============================================================================
+# Token Usage Tracking
+# ============================================================================
+# Track LLM token usage per model call (input/output/total tokens)
+# Logs at info level via TokenUsageMiddleware
+token_usage:
+  enabled: false
+
 # ============================================================================
 # Models Configuration
 # ============================================================================

scripts/serve.sh

@@ -122,7 +122,10 @@ else
 fi
 
 echo "Starting LangGraph server..."
-(cd backend && NO_COLOR=1 uv run langgraph dev --no-browser --allow-blocking $LANGGRAPH_EXTRA_FLAGS > ../logs/langgraph.log 2>&1) &
+# Read log_level from config.yaml, fallback to env var, then to "info"
+CONFIG_LOG_LEVEL=$(grep -m1 '^log_level:' config.yaml 2>/dev/null | awk '{print $2}' | tr -d ' ')
+LANGGRAPH_LOG_LEVEL="${LANGGRAPH_LOG_LEVEL:-${CONFIG_LOG_LEVEL:-info}}"
+(cd backend && NO_COLOR=1 uv run langgraph dev --no-browser --allow-blocking --server-log-level $LANGGRAPH_LOG_LEVEL $LANGGRAPH_EXTRA_FLAGS > ../logs/langgraph.log 2>&1) &
 ./scripts/wait-for-port.sh 2024 60 "LangGraph" || {
     echo "  See logs/langgraph.log for details"
     tail -20 logs/langgraph.log