Initial commit: hardened DeerFlow factory

Vendored deer-flow upstream (bytedance/deer-flow) plus prompt-injection
hardening:

- New deerflow.security package: content_delimiter, html_cleaner,
  sanitizer (8 layers — invisible chars, control chars, symbols, NFC,
  PUA, tag chars, horizontal whitespace collapse with newline/tab
  preservation, length cap)
- New deerflow.community.searx package: web_search, web_fetch,
  image_search backed by a private SearX instance, every external
  string sanitized and wrapped in <<<EXTERNAL_UNTRUSTED_CONTENT>>>
  delimiters
- All native community web providers (ddg_search, tavily, exa,
  firecrawl, jina_ai, infoquest, image_search) replaced with hard-fail
  stubs that raise NativeWebToolDisabledError at import time, so a
  misconfigured tool.use path fails loud rather than silently falling
  back to unsanitized output
- Native client back-doors (jina_client.py, infoquest_client.py)
  stubbed too
- Native-tool tests quarantined under tests/_disabled_native/
  (collect_ignore_glob via local conftest.py)
- Sanitizer Layer 7 fix: only collapse horizontal whitespace, preserve
  newlines and tabs so list/table structure survives
- Hardened runtime config.yaml references only the searx-backed tools
- Factory overlay (backend/) kept in sync with deer-flow tree as a
  reference / source

See HARDENING.md for the full audit trail and verification steps.

deer-flow/backend/app/gateway/routers/runs.py

@@ -0,0 +1,87 @@
+"""Stateless runs endpoints -- stream and wait without a pre-existing thread.
+
+These endpoints auto-create a temporary thread when no ``thread_id`` is
+supplied in the request body.  When a ``thread_id`` **is** provided, it
+is reused so that conversation history is preserved across calls.
+"""
+
+from __future__ import annotations
+
+import asyncio
+import logging
+import uuid
+
+from fastapi import APIRouter, Request
+from fastapi.responses import StreamingResponse
+
+from app.gateway.deps import get_checkpointer, get_run_manager, get_stream_bridge
+from app.gateway.routers.thread_runs import RunCreateRequest
+from app.gateway.services import sse_consumer, start_run
+from deerflow.runtime import serialize_channel_values
+
+logger = logging.getLogger(__name__)
+router = APIRouter(prefix="/api/runs", tags=["runs"])
+
+
+def _resolve_thread_id(body: RunCreateRequest) -> str:
+    """Return the thread_id from the request body, or generate a new one."""
+    thread_id = (body.config or {}).get("configurable", {}).get("thread_id")
+    if thread_id:
+        return str(thread_id)
+    return str(uuid.uuid4())
+
+
+@router.post("/stream")
+async def stateless_stream(body: RunCreateRequest, request: Request) -> StreamingResponse:
+    """Create a run and stream events via SSE.
+
+    If ``config.configurable.thread_id`` is provided, the run is created
+    on the given thread so that conversation history is preserved.
+    Otherwise a new temporary thread is created.
+    """
+    thread_id = _resolve_thread_id(body)
+    bridge = get_stream_bridge(request)
+    run_mgr = get_run_manager(request)
+    record = await start_run(body, thread_id, request)
+
+    return StreamingResponse(
+        sse_consumer(bridge, record, request, run_mgr),
+        media_type="text/event-stream",
+        headers={
+            "Cache-Control": "no-cache",
+            "Connection": "keep-alive",
+            "X-Accel-Buffering": "no",
+            "Content-Location": f"/api/threads/{thread_id}/runs/{record.run_id}",
+        },
+    )
+
+
+@router.post("/wait", response_model=dict)
+async def stateless_wait(body: RunCreateRequest, request: Request) -> dict:
+    """Create a run and block until completion.
+
+    If ``config.configurable.thread_id`` is provided, the run is created
+    on the given thread so that conversation history is preserved.
+    Otherwise a new temporary thread is created.
+    """
+    thread_id = _resolve_thread_id(body)
+    record = await start_run(body, thread_id, request)
+
+    if record.task is not None:
+        try:
+            await record.task
+        except asyncio.CancelledError:
+            pass
+
+    checkpointer = get_checkpointer(request)
+    config = {"configurable": {"thread_id": thread_id}}
+    try:
+        checkpoint_tuple = await checkpointer.aget_tuple(config)
+        if checkpoint_tuple is not None:
+            checkpoint = getattr(checkpoint_tuple, "checkpoint", {}) or {}
+            channel_values = checkpoint.get("channel_values", {})
+            return serialize_channel_values(channel_values)
+    except Exception:
+        logger.exception("Failed to fetch final state for run %s", record.run_id)
+
+    return {"status": record.status.value, "error": record.error}