fix(api-server): bind request session context for tools

gateway/platforms/api_server.py

@@ -3510,35 +3510,46 @@ class APIServerAdapter(BasePlatformAdapter):
         loop = asyncio.get_running_loop()
 
         def _run():
-            agent = self._create_agent(
-                ephemeral_system_prompt=ephemeral_system_prompt,
-                session_id=session_id,
-                stream_delta_callback=stream_delta_callback,
-                tool_progress_callback=tool_progress_callback,
-                tool_start_callback=tool_start_callback,
-                tool_complete_callback=tool_complete_callback,
-                gateway_session_key=gateway_session_key,
+            from gateway.session_context import clear_session_vars, set_session_vars
+
+            tokens = set_session_vars(
+                platform="api_server",
+                chat_id=session_id or "",
+                session_key=gateway_session_key or session_id or "",
+                session_id=session_id or "",
             )
-            if agent_ref is not None:
-                agent_ref[0] = agent
-            effective_task_id = session_id or str(uuid.uuid4())
-            result = agent.run_conversation(
-                user_message=user_message,
-                conversation_history=conversation_history,
-                task_id=effective_task_id,
-            )
-            usage = {
-                "input_tokens": getattr(agent, "session_prompt_tokens", 0) or 0,
-                "output_tokens": getattr(agent, "session_completion_tokens", 0) or 0,
-                "total_tokens": getattr(agent, "session_total_tokens", 0) or 0,
-            }
-            # Include the effective session ID in the result so callers
-            # (e.g. X-Hermes-Session-Id header) can track compression-
-            # triggered session rotations. (#16938)
-            _eff_sid = getattr(agent, "session_id", session_id)
-            if isinstance(_eff_sid, str) and _eff_sid:
-                result["session_id"] = _eff_sid
-            return result, usage
+            try:
+                agent = self._create_agent(
+                    ephemeral_system_prompt=ephemeral_system_prompt,
+                    session_id=session_id,
+                    stream_delta_callback=stream_delta_callback,
+                    tool_progress_callback=tool_progress_callback,
+                    tool_start_callback=tool_start_callback,
+                    tool_complete_callback=tool_complete_callback,
+                    gateway_session_key=gateway_session_key,
+                )
+                if agent_ref is not None:
+                    agent_ref[0] = agent
+                effective_task_id = session_id or str(uuid.uuid4())
+                result = agent.run_conversation(
+                    user_message=user_message,
+                    conversation_history=conversation_history,
+                    task_id=effective_task_id,
+                )
+                usage = {
+                    "input_tokens": getattr(agent, "session_prompt_tokens", 0) or 0,
+                    "output_tokens": getattr(agent, "session_completion_tokens", 0) or 0,
+                    "total_tokens": getattr(agent, "session_total_tokens", 0) or 0,
+                }
+                # Include the effective session ID in the result so callers
+                # (e.g. X-Hermes-Session-Id header) can track compression-
+                # triggered session rotations. (#16938)
+                _eff_sid = getattr(agent, "session_id", session_id)
+                if isinstance(_eff_sid, str) and _eff_sid:
+                    result["session_id"] = _eff_sid
+                return result, usage
+            finally:
+                clear_session_vars(tokens)
 
         return await loop.run_in_executor(None, _run)
 

gateway/session_context.py

@@ -106,6 +106,7 @@ def set_session_vars(
     user_id: str = "",
     user_name: str = "",
     session_key: str = "",
+    session_id: str = "",
     message_id: str = "",
     cwd: str = "",
 ) -> list:
@@ -127,6 +128,7 @@ def set_session_vars(
         _SESSION_USER_ID.set(user_id),
         _SESSION_USER_NAME.set(user_name),
         _SESSION_KEY.set(session_key),
+        _SESSION_ID.set(session_id),
         _SESSION_MESSAGE_ID.set(message_id),
     ]
     try:
@@ -157,6 +159,7 @@ def clear_session_vars(tokens: list) -> None:
         _SESSION_USER_ID,
         _SESSION_USER_NAME,
         _SESSION_KEY,
+        _SESSION_ID,
         _SESSION_MESSAGE_ID,
     ):
         var.set("")

tests/gateway/test_session_api.py

@@ -75,6 +75,54 @@ async def test_capabilities_advertises_session_control_surface(adapter):
     }
 
 
+@pytest.mark.asyncio
+async def test_run_agent_binds_api_session_context_for_tool_env(adapter, monkeypatch):
+    """API-server request sessions should reach tools and terminal subprocess env."""
+    monkeypatch.setenv("HERMES_SESSION_ID", "stale-session")
+    observed = {}
+
+    class FakeAgent:
+        session_prompt_tokens = 0
+        session_completion_tokens = 0
+        session_total_tokens = 0
+
+        def __init__(self, session_id: str):
+            self.session_id = session_id
+
+        def run_conversation(self, user_message, conversation_history, task_id):
+            from gateway.session_context import get_session_env
+            from tools.environments.local import _make_run_env
+
+            observed["task_id"] = task_id
+            observed["context_session_id"] = get_session_env("HERMES_SESSION_ID")
+            observed["context_platform"] = get_session_env("HERMES_SESSION_PLATFORM")
+            observed["context_session_key"] = get_session_env("HERMES_SESSION_KEY")
+            observed["child_session_id"] = _make_run_env({}).get("HERMES_SESSION_ID")
+            return {"final_response": "ok"}
+
+    def fake_create_agent(**kwargs):
+        return FakeAgent(kwargs["session_id"])
+
+    monkeypatch.setattr(adapter, "_create_agent", fake_create_agent)
+
+    result, usage = await adapter._run_agent(
+        user_message="hello",
+        conversation_history=[],
+        session_id="request-session",
+        gateway_session_key="request-key",
+    )
+
+    assert result["session_id"] == "request-session"
+    assert usage == {"input_tokens": 0, "output_tokens": 0, "total_tokens": 0}
+    assert observed == {
+        "task_id": "request-session",
+        "context_session_id": "request-session",
+        "context_platform": "api_server",
+        "context_session_key": "request-key",
+        "child_session_id": "request-session",
+    }
+
+
 @pytest.mark.asyncio
 async def test_session_crud_and_message_history(adapter, session_db):
     app = _create_session_app(adapter)

tests/gateway/test_session_env.py

@@ -190,6 +190,17 @@ def test_session_key_falls_back_to_os_environ(monkeypatch):
     assert get_session_env("HERMES_SESSION_KEY") == ""
 
 
+def test_session_id_set_via_contextvars(monkeypatch):
+    """set_session_vars should set HERMES_SESSION_ID via contextvars."""
+    monkeypatch.setenv("HERMES_SESSION_ID", "stale-env-session")
+
+    tokens = set_session_vars(session_id="ctx-session-456")
+    assert get_session_env("HERMES_SESSION_ID") == "ctx-session-456"
+
+    clear_session_vars(tokens)
+    assert get_session_env("HERMES_SESSION_ID") == ""
+
+
 def test_set_session_env_includes_session_key():
     """_set_session_env should propagate session_key from SessionContext."""
     runner = object.__new__(GatewayRunner)