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/tests/test_memory_queue.py

@@ -0,0 +1,91 @@
+from unittest.mock import MagicMock, patch
+
+from deerflow.agents.memory.queue import ConversationContext, MemoryUpdateQueue
+from deerflow.config.memory_config import MemoryConfig
+
+
+def _memory_config(**overrides: object) -> MemoryConfig:
+    config = MemoryConfig()
+    for key, value in overrides.items():
+        setattr(config, key, value)
+    return config
+
+
+def test_queue_add_preserves_existing_correction_flag_for_same_thread() -> None:
+    queue = MemoryUpdateQueue()
+
+    with (
+        patch("deerflow.agents.memory.queue.get_memory_config", return_value=_memory_config(enabled=True)),
+        patch.object(queue, "_reset_timer"),
+    ):
+        queue.add(thread_id="thread-1", messages=["first"], correction_detected=True)
+        queue.add(thread_id="thread-1", messages=["second"], correction_detected=False)
+
+    assert len(queue._queue) == 1
+    assert queue._queue[0].messages == ["second"]
+    assert queue._queue[0].correction_detected is True
+
+
+def test_process_queue_forwards_correction_flag_to_updater() -> None:
+    queue = MemoryUpdateQueue()
+    queue._queue = [
+        ConversationContext(
+            thread_id="thread-1",
+            messages=["conversation"],
+            agent_name="lead_agent",
+            correction_detected=True,
+        )
+    ]
+    mock_updater = MagicMock()
+    mock_updater.update_memory.return_value = True
+
+    with patch("deerflow.agents.memory.updater.MemoryUpdater", return_value=mock_updater):
+        queue._process_queue()
+
+    mock_updater.update_memory.assert_called_once_with(
+        messages=["conversation"],
+        thread_id="thread-1",
+        agent_name="lead_agent",
+        correction_detected=True,
+        reinforcement_detected=False,
+    )
+
+
+def test_queue_add_preserves_existing_reinforcement_flag_for_same_thread() -> None:
+    queue = MemoryUpdateQueue()
+
+    with (
+        patch("deerflow.agents.memory.queue.get_memory_config", return_value=_memory_config(enabled=True)),
+        patch.object(queue, "_reset_timer"),
+    ):
+        queue.add(thread_id="thread-1", messages=["first"], reinforcement_detected=True)
+        queue.add(thread_id="thread-1", messages=["second"], reinforcement_detected=False)
+
+    assert len(queue._queue) == 1
+    assert queue._queue[0].messages == ["second"]
+    assert queue._queue[0].reinforcement_detected is True
+
+
+def test_process_queue_forwards_reinforcement_flag_to_updater() -> None:
+    queue = MemoryUpdateQueue()
+    queue._queue = [
+        ConversationContext(
+            thread_id="thread-1",
+            messages=["conversation"],
+            agent_name="lead_agent",
+            reinforcement_detected=True,
+        )
+    ]
+    mock_updater = MagicMock()
+    mock_updater.update_memory.return_value = True
+
+    with patch("deerflow.agents.memory.updater.MemoryUpdater", return_value=mock_updater):
+        queue._process_queue()
+
+    mock_updater.update_memory.assert_called_once_with(
+        messages=["conversation"],
+        thread_id="thread-1",
+        agent_name="lead_agent",
+        correction_detected=False,
+        reinforcement_detected=True,
+    )