diff --git a/agent/subagent_context_middleware.py b/agent/subagent_context_middleware.py
new file mode 100644
index 0000000..98d1422
--- /dev/null
+++ b/agent/subagent_context_middleware.py
@@ -0,0 +1,95 @@
+"""Middleware that tags logs with the currently executing subagent name.
+
+Each subagent receives its own instance of this middleware (carrying its name).
+The middleware writes the name into the request-scoped GlobalContext (`g.subagent`)
+for the duration of every model call and tool call, so the log Formatter can render
+which subagent produced each log line. The previous value is restored afterwards so
+that nested/parallel subagents and the main agent are not affected.
+"""
+
+import logging
+from typing import Any, Awaitable, Callable
+
+from langchain.agents.middleware import AgentMiddleware
+from langchain.agents.middleware.types import ModelRequest, ModelResponse
+from langchain.tools.tool_node import ToolCallRequest
+
+from utils.log_util.context import g
+
+logger = logging.getLogger("app")
+
+# Context key consumed by utils/log_util/logger.py Formatter.
+_SUBAGENT_KEY = "subagent"
+
+
+class SubagentContextMiddleware(AgentMiddleware):
+    """Set `g.subagent` while this subagent's model/tool calls execute."""
+
+    def __init__(self, subagent_name: str) -> None:
+        super().__init__()
+        self._subagent_name = subagent_name
+
+    def _enter(self) -> dict:
+        # Shallow-copy the whole context dict and rebind a PRIVATE copy for this
+        # context. This is load-bearing: GlobalContext mutates a shared dict in
+        # place, and asyncio task copies share that reference, so a plain
+        # `g.subagent = name` would leak across parallel sibling subagents and
+        # race on restore. Replacing the reference isolates each context.
+        try:
+            prev = dict(g.get_context())
+        except LookupError:
+            prev = {}
+        new_ctx = dict(prev)
+        new_ctx[_SUBAGENT_KEY] = self._subagent_name
+        g.update_context(new_ctx)
+        return prev
+
+    def _exit(self, prev: dict) -> None:
+        # Restore by rebinding the previous dict (also a private copy).
+        g.update_context(dict(prev))
+
+    # ----- model call -----
+    def wrap_model_call(
+        self,
+        request: ModelRequest,
+        handler: Callable[[ModelRequest], ModelResponse],
+    ) -> ModelResponse:
+        prev = self._enter()
+        try:
+            return handler(request)
+        finally:
+            self._exit(prev)
+
+    async def awrap_model_call(
+        self,
+        request: ModelRequest,
+        handler: Callable[[ModelRequest], Awaitable[ModelResponse]],
+    ) -> ModelResponse:
+        prev = self._enter()
+        try:
+            return await handler(request)
+        finally:
+            self._exit(prev)
+
+    # ----- tool call -----
+    def wrap_tool_call(
+        self,
+        request: ToolCallRequest,
+        handler: Callable[[ToolCallRequest], Any],
+    ) -> Any:
+        prev = self._enter()
+        try:
+            return handler(request)
+        finally:
+            self._exit(prev)
+
+    async def awrap_tool_call(
+        self,
+        request: ToolCallRequest,
+        handler: Callable[[ToolCallRequest], Awaitable[Any]],
+    ) -> Any:
+        prev = self._enter()
+        try:
+            return await handler(request)
+        finally:
+            self._exit(prev)
diff --git a/agent/subagent_loader.py b/agent/subagent_loader.py
index ed18fb9..f27d051 100644
--- a/agent/subagent_loader.py
+++ b/agent/subagent_loader.py
@@ -25,6 +25,7 @@ from langchain.tools import BaseTool
 from langchain_core.language_models import BaseChatModel
 
 from agent.plugin_hook_loader import _get_skill_dirs
+from agent.subagent_context_middleware import SubagentContextMiddleware
 
 logger = logging.getLogger('app')
 
@@ -181,6 +182,8 @@ async def load_subagents(
             "system_prompt": parsed["system_prompt"],
             "model": model,
             "tools": filtered_tools,
+            # Tag this subagent's model/tool logs with its name.
+            "middleware": [SubagentContextMiddleware(name)],
         }
         subagents.append(subagent)
         logger.info(f"Loaded sub-agent '{name}' with {len(filtered_tools)} tools from {parsed['source']}")
diff --git a/utils/log_util/logger.py b/utils/log_util/logger.py
index b6e98ba..a88f5ae 100644
--- a/utils/log_util/logger.py
+++ b/utils/log_util/logger.py
@@ -51,6 +51,13 @@ class Formatter(logging.Formatter):
                 record.trace_id = getattr(g, "trace_id")
             except LookupError:
                 record.trace_id = "N/A"
+        # Handle subagent - default to "main" for the orchestrator / no-context paths.
+        # Catch KeyError too: GlobalContext.__getattr__ raises KeyError on a missing key.
+        if not hasattr(record, "subagent"):
+            try:
+                record.subagent = getattr(g, "subagent")
+            except (KeyError, LookupError):
+                record.subagent = "main"
         # Handle user_id
         # if not hasattr(record, "user_id"):
         #     record.user_id = getattr(g, "user_id")
@@ -65,7 +72,7 @@ class Formatter(logging.Formatter):
 def init_logger_once(name,level):
     logger = logging.getLogger(name)
     logger.setLevel(level=level)
-    formatter = Formatter("%(timestamp)s | %(levelname)-5s | %(trace_id)s | %(name)s:%(funcName)s:%(lineno)s - %(message)s", datefmt='%Y-%m-%d %H:%M:%S.%f')
+    formatter = Formatter("%(timestamp)s | %(levelname)-5s | %(trace_id)s | %(subagent)s | %(name)s:%(funcName)s:%(lineno)s - %(message)s", datefmt='%Y-%m-%d %H:%M:%S.%f')
     handler = logging.StreamHandler()
     handler.setFormatter(formatter)
     logger.addHandler(handler)