fix(sandbox): avoid blocking sandbox readiness polling (#2822)

* fix(sandbox): offload async sandbox acquisition

Run blocking sandbox provider acquisition through the async provider hook so eager sandbox setup does not stall the event loop.

* fix(sandbox): add async readiness polling

Introduce an async sandbox readiness poller using httpx and asyncio.sleep while preserving the existing synchronous API.

* test(sandbox): cover async readiness polling

Lock in non-blocking readiness behavior so the async helper does not regress to requests.get or time.sleep.

* fix(sandbox): allow anonymous backend creation

* fix(sandbox): use async readiness in provider acquisition

* fix(sandbox): use async acquisition for lazy tools

* test(sandbox): cover anonymous remote creation

* fix(sandbox): clamp async readiness timeout budget

* fix(sandbox): offload async lock file handling

* fix(sandbox): delegate async middleware fallthrough

* docs(sandbox): document async acquisition path

* fix(sandbox): offload async sandbox release

* docs(sandbox): mention async release hook

* fix(sandbox): address async lock review

Reduce duplicate sync/async sandbox acquisition state handling and move async thread-lock waits onto a dedicated executor with cancellation-safe cleanup.

* chore: retrigger ci

Retrigger GitHub Actions after upstream main fixed the stale PR merge lint failure.

* test(sandbox): sync backend unit fixtures

---------

Co-authored-by: Willem Jiang <willem.jiang@gmail.com>

backend/packages/harness/deerflow/community/aio_sandbox/backend.py

@@ -2,10 +2,12 @@
 
 from __future__ import annotations
 
+import asyncio
 import logging
 import time
 from abc import ABC, abstractmethod
 
+import httpx
 import requests
 
 from .sandbox_info import SandboxInfo
@@ -35,6 +37,34 @@ def wait_for_sandbox_ready(sandbox_url: str, timeout: int = 30) -> bool:
     return False
 
 
+async def wait_for_sandbox_ready_async(sandbox_url: str, timeout: int = 30, poll_interval: float = 1.0) -> bool:
+    """Async variant of sandbox readiness polling.
+
+    Use this from async runtime paths so sandbox startup waits do not block the
+    event loop. The synchronous ``wait_for_sandbox_ready`` function remains for
+    existing synchronous backend/provider call sites.
+    """
+    loop = asyncio.get_running_loop()
+    deadline = loop.time() + timeout
+
+    async with httpx.AsyncClient(timeout=5) as client:
+        while True:
+            remaining = deadline - loop.time()
+            if remaining <= 0:
+                break
+            try:
+                response = await client.get(f"{sandbox_url}/v1/sandbox", timeout=min(5.0, remaining))
+                if response.status_code == 200:
+                    return True
+            except httpx.RequestError:
+                pass
+            remaining = deadline - loop.time()
+            if remaining <= 0:
+                break
+            await asyncio.sleep(min(poll_interval, remaining))
+    return False
+
+
 class SandboxBackend(ABC):
     """Abstract base for sandbox provisioning backends.
 
@@ -44,7 +74,7 @@ class SandboxBackend(ABC):
     """
 
     @abstractmethod
-    def create(self, thread_id: str, sandbox_id: str, extra_mounts: list[tuple[str, str, bool]] | None = None) -> SandboxInfo:
+    def create(self, thread_id: str | None, sandbox_id: str, extra_mounts: list[tuple[str, str, bool]] | None = None) -> SandboxInfo:
         """Create/provision a new sandbox.
 
         Args: