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/packages/harness/deerflow/config/model_config.py

@@ -0,0 +1,41 @@
+from pydantic import BaseModel, ConfigDict, Field
+
+
+class ModelConfig(BaseModel):
+    """Config section for a model"""
+
+    name: str = Field(..., description="Unique name for the model")
+    display_name: str | None = Field(..., default_factory=lambda: None, description="Display name for the model")
+    description: str | None = Field(..., default_factory=lambda: None, description="Description for the model")
+    use: str = Field(
+        ...,
+        description="Class path of the model provider(e.g. langchain_openai.ChatOpenAI)",
+    )
+    model: str = Field(..., description="Model name")
+    model_config = ConfigDict(extra="allow")
+    use_responses_api: bool | None = Field(
+        default=None,
+        description="Whether to route OpenAI ChatOpenAI calls through the /v1/responses API",
+    )
+    output_version: str | None = Field(
+        default=None,
+        description="Structured output version for OpenAI responses content, e.g. responses/v1",
+    )
+    supports_thinking: bool = Field(default_factory=lambda: False, description="Whether the model supports thinking")
+    supports_reasoning_effort: bool = Field(default_factory=lambda: False, description="Whether the model supports reasoning effort")
+    when_thinking_enabled: dict | None = Field(
+        default_factory=lambda: None,
+        description="Extra settings to be passed to the model when thinking is enabled",
+    )
+    when_thinking_disabled: dict | None = Field(
+        default_factory=lambda: None,
+        description="Extra settings to be passed to the model when thinking is disabled",
+    )
+    supports_vision: bool = Field(default_factory=lambda: False, description="Whether the model supports vision/image inputs")
+    thinking: dict | None = Field(
+        default_factory=lambda: None,
+        description=(
+            "Thinking settings for the model. If provided, these settings will be passed to the model when thinking is enabled. "
+            "This is a shortcut for `when_thinking_enabled` and will be merged with `when_thinking_enabled` if both are provided."
+        ),
+    )