diff --git a/apps/agent/agent/middleware/open_pr.py b/apps/agent/agent/middleware/open_pr.py
index af19bf70..82388a53 100644
--- a/apps/agent/agent/middleware/open_pr.py
+++ b/apps/agent/agent/middleware/open_pr.py
@@ -136,12 +136,7 @@ I've {action} pull request to address this issue:
         commit_message = pr_payload.get("commit_message", pr_title)
 
         if not thread_id:
-            if linear_issue_id and last_message_content:
-                comment = f"""🤖 **Agent Response**
-
-{last_message_content}"""
-                await comment_on_linear_issue(linear_issue_id, comment)
-            return None
+            raise ValueError("Missing thread_id in middleware config")
 
         repo_config = configurable.get("repo", {})
         repo_owner = repo_config.get("owner")
diff --git a/apps/agent/agent/server.py b/apps/agent/agent/server.py
index b3d92cb7..1f808984 100644
--- a/apps/agent/agent/server.py
+++ b/apps/agent/agent/server.py
@@ -9,6 +9,7 @@ import warnings
 
 logger = logging.getLogger(__name__)
 
+from langgraph.config import get_config
 from langgraph.graph.state import RunnableConfig
 from langgraph.pregel import Pregel
 from langgraph_sdk import get_client
@@ -45,7 +46,7 @@ SANDBOX_CREATING = "__creating__"
 SANDBOX_CREATION_TIMEOUT = 180
 SANDBOX_POLL_INTERVAL = 1.0
 
-from .utils.sandbox_state import SANDBOX_BACKENDS
+from .utils.sandbox_state import SANDBOX_BACKENDS, get_sandbox_id_from_metadata
 
 
 async def _clone_or_pull_repo_in_sandbox(  # noqa: PLR0915
@@ -161,12 +162,6 @@ async def _clone_or_pull_repo_in_sandbox(  # noqa: PLR0915
     return repo_dir
 
 
-async def _get_sandbox_id_from_metadata(thread_id: str) -> str | None:
-    """Get sandbox_id from thread metadata."""
-    thread = await client.threads.get(thread_id=thread_id)
-    return thread.get("metadata", {}).get("sandbox_id")
-
-
 async def _wait_for_sandbox_id(thread_id: str) -> str:
     """Wait for sandbox_id to be set in thread metadata.
 
@@ -178,7 +173,7 @@ async def _wait_for_sandbox_id(thread_id: str) -> str:
     """
     elapsed = 0.0
     while elapsed < SANDBOX_CREATION_TIMEOUT:
-        sandbox_id = await _get_sandbox_id_from_metadata(thread_id)
+        sandbox_id = await get_sandbox_id_from_metadata(thread_id)
         if sandbox_id is not None and sandbox_id != SANDBOX_CREATING:
             return sandbox_id
         await asyncio.sleep(SANDBOX_POLL_INTERVAL)
@@ -224,7 +219,7 @@ async def get_agent(config: RunnableConfig) -> Pregel:  # noqa: PLR0915
         ).with_config(config)
 
     sandbox_backend = SANDBOX_BACKENDS.get(thread_id)
-    sandbox_id = await _get_sandbox_id_from_metadata(thread_id)
+    sandbox_id = await get_sandbox_id_from_metadata(thread_id)
 
     if sandbox_id == SANDBOX_CREATING and not sandbox_backend:
         logger.info("Sandbox creation in progress, waiting...")
@@ -232,8 +227,8 @@ async def get_agent(config: RunnableConfig) -> Pregel:  # noqa: PLR0915
 
     if sandbox_backend:
         logger.info("Using cached sandbox backend for thread %s", thread_id)
-        thread = await client.threads.get(thread_id=thread_id)
-        repo_dir = thread.get("metadata", {}).get("repo_dir")
+        metadata = get_config().get("metadata", {})
+        repo_dir = metadata.get("repo_dir")
 
         if repo_owner and repo_name:
             logger.info("Pulling latest changes for repo %s/%s", repo_owner, repo_name)
@@ -308,8 +303,8 @@ async def get_agent(config: RunnableConfig) -> Pregel:  # noqa: PLR0915
                 await client.threads.update(thread_id=thread_id, metadata={"sandbox_id": None})
                 raise
 
-        thread = await client.threads.get(thread_id=thread_id)
-        repo_dir = thread.get("metadata", {}).get("repo_dir")
+        metadata = get_config().get("metadata", {})
+        repo_dir = metadata.get("repo_dir")
 
         if repo_owner and repo_name:
             logger.info("Pulling latest changes for repo %s/%s", repo_owner, repo_name)
diff --git a/apps/agent/agent/utils/sandbox_state.py b/apps/agent/agent/utils/sandbox_state.py
index 46adc855..98f97ff0 100644
--- a/apps/agent/agent/utils/sandbox_state.py
+++ b/apps/agent/agent/utils/sandbox_state.py
@@ -6,25 +6,24 @@ import asyncio
 import logging
 from typing import Any
 
-from langgraph_sdk import get_client
+from langgraph.config import get_config
 
 from ..integrations.langsmith import _create_langsmith_sandbox
 
 logger = logging.getLogger(__name__)
-client = get_client()
 
 # Thread ID -> SandboxBackend mapping, shared between server.py and middleware
 SANDBOX_BACKENDS: dict[str, Any] = {}
 
 
-async def _get_sandbox_id_from_metadata(thread_id: str) -> str | None:
+async def get_sandbox_id_from_metadata(thread_id: str) -> str | None:
     """Fetch sandbox_id from thread metadata."""
     try:
-        thread = await client.threads.get(thread_id=thread_id)
+        config = get_config()
     except Exception:
-        logger.exception("Failed to fetch thread metadata for sandbox")
+        logger.exception("Failed to read thread metadata for sandbox")
         return None
-    return thread.get("metadata", {}).get("sandbox_id")
+    return config.get("metadata", {}).get("sandbox_id")
 
 
 async def get_sandbox_backend(thread_id: str) -> Any | None:
@@ -33,9 +32,9 @@ async def get_sandbox_backend(thread_id: str) -> Any | None:
     if sandbox_backend:
         return sandbox_backend
 
-    sandbox_id = await _get_sandbox_id_from_metadata(thread_id)
+    sandbox_id = await get_sandbox_id_from_metadata(thread_id)
     if not sandbox_id:
-        return None
+        raise ValueError(f"Missing sandbox_id in thread metadata for {thread_id}")
 
     sandbox_backend = await asyncio.to_thread(_create_langsmith_sandbox, sandbox_id)
     SANDBOX_BACKENDS[thread_id] = sandbox_backend