diff --git a/pyisolate/runtime/thread.py b/pyisolate/runtime/thread.py
index 49ec62f..e7a44a2 100644
--- a/pyisolate/runtime/thread.py
+++ b/pyisolate/runtime/thread.py
@@ -513,6 +513,40 @@ def snapshot(self) -> dict:
             "child_work_max": self.child_work_max,
         }
 
+    def reset_config(self) -> dict[str, Any]:
+        """Return the runtime options consumed by ``reset`` for reconfiguration."""
+        return {
+            "policy": self.policy,
+            "cpu_ms": self.cpu_quota_ms,
+            "mem_bytes": self.mem_quota_bytes,
+            "wall_time_ms": self.wall_time_ms,
+            "open_files_max": self.open_files_max,
+            "network_ops_max": self.network_ops_max,
+            "output_bytes_max": self.output_bytes_max,
+            "child_work_max": self.child_work_max,
+            "allowed_imports": sorted(self.allowed_imports)
+            if self.allowed_imports is not None
+            else None,
+            "numa_node": self.numa_node,
+            "capabilities": serialize_capabilities(self._capabilities),
+        }
+
+    def apply_reset_config(self, config: dict[str, Any]) -> None:
+        """Apply a serialized runtime config produced by ``reset_config``."""
+        self.policy = config.get("policy")
+        self.cpu_quota_ms = config.get("cpu_ms")
+        self.mem_quota_bytes = config.get("mem_bytes")
+        self.wall_time_ms = config.get("wall_time_ms")
+        self.open_files_max = config.get("open_files_max")
+        self.network_ops_max = config.get("network_ops_max")
+        self.output_bytes_max = config.get("output_bytes_max")
+        self.child_work_max = config.get("child_work_max")
+        self.numa_node = config.get("numa_node")
+        self.allowed_imports = self._merge_allowed_imports(
+            self.policy, config.get("allowed_imports")
+        )
+        self._capabilities = deserialize_capabilities(config.get("capabilities"))
+
     @staticmethod
     def _estimate_output_size(item: Any) -> int:
         if isinstance(item, bytes):
diff --git a/pyisolate/supervisor.py b/pyisolate/supervisor.py
index 1cadb4f..7830f2d 100644
--- a/pyisolate/supervisor.py
+++ b/pyisolate/supervisor.py
@@ -67,21 +67,12 @@ def quarantine(self, reason: str = "manual quarantine") -> None:
         self._supervisor.quarantine(self._thread.name, reason)
 
     def reset(self) -> None:
+        reset_config = self._thread.reset_config()
+        # Keep this reset path aligned with Supervisor.spawn warm-pool reuse.
         self._thread.reset(
             self._thread.name,
-            policy=self._thread.policy,
-            cpu_ms=self._thread.cpu_quota_ms,
-            mem_bytes=self._thread.mem_quota_bytes,
-            wall_time_ms=self._thread.wall_time_ms,
-            open_files_max=self._thread.open_files_max,
-            network_ops_max=self._thread.network_ops_max,
-            output_bytes_max=self._thread.output_bytes_max,
-            child_work_max=self._thread.child_work_max,
-            allowed_imports=sorted(self._thread.allowed_imports)
-            if self._thread.allowed_imports is not None
-            else None,
-            numa_node=self._thread.numa_node,
             cgroup_path=self._thread._cgroup_path,
+            **reset_config,
         )
 
     def recycle(self) -> "Sandbox":
@@ -254,42 +245,36 @@ def spawn(
             try:
                 cg_path = cgroup.create(name, cpu_ms, mem_bytes)
                 temp_dir = recovery.allocate_temp_dir(name)
+                reset_config = {
+                    "policy": policy,
+                    "cpu_ms": cpu_ms,
+                    "mem_bytes": mem_bytes,
+                    "wall_time_ms": wall_time_ms,
+                    "open_files_max": open_files_max,
+                    "network_ops_max": network_ops_max,
+                    "output_bytes_max": output_bytes_max,
+                    "child_work_max": child_work_max,
+                    "allowed_imports": allowed_imports,
+                    "numa_node": numa_node,
+                    "capabilities": capabilities,
+                }
                 if self._warm_pool:
                     thread = self._warm_pool.pop()
+                    # Intentionally mirrors Sandbox.reset by sharing reset_config.
                     thread.reset(
                         name,
-                        policy=policy,
-                        cpu_ms=cpu_ms,
-                        mem_bytes=mem_bytes,
-                        wall_time_ms=wall_time_ms,
-                        open_files_max=open_files_max,
-                        network_ops_max=network_ops_max,
-                        output_bytes_max=output_bytes_max,
-                        child_work_max=child_work_max,
-                        allowed_imports=allowed_imports,
-                        numa_node=numa_node,
                         cgroup_path=cg_path,
-                        capabilities=capabilities,
+                        **reset_config,
                     )
                     thread._on_violation = self._alerts.notify
                     thread._tracer = self._tracer
                 else:
                     thread = SandboxThread(
                         name=name,
-                        policy=policy,
-                        cpu_ms=cpu_ms,
-                        mem_bytes=mem_bytes,
-                        wall_time_ms=wall_time_ms,
-                        open_files_max=open_files_max,
-                        network_ops_max=network_ops_max,
-                        output_bytes_max=output_bytes_max,
-                        child_work_max=child_work_max,
-                        allowed_imports=allowed_imports,
+                        **reset_config,
                         on_violation=self._alerts.notify,
                         tracer=self._tracer,
-                        numa_node=numa_node,
                         cgroup_path=cg_path,
-                        capabilities=capabilities,
                     )
                     thread.start()
                 thread._temp_dir = temp_dir