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/guardrails_config.py

@@ -0,0 +1,48 @@
+"""Configuration for pre-tool-call authorization."""
+
+from pydantic import BaseModel, Field
+
+
+class GuardrailProviderConfig(BaseModel):
+    """Configuration for a guardrail provider."""
+
+    use: str = Field(description="Class path (e.g. 'deerflow.guardrails.builtin:AllowlistProvider')")
+    config: dict = Field(default_factory=dict, description="Provider-specific settings passed as kwargs")
+
+
+class GuardrailsConfig(BaseModel):
+    """Configuration for pre-tool-call authorization.
+
+    When enabled, every tool call passes through the configured provider
+    before execution. The provider receives tool name, arguments, and the
+    agent's passport reference, and returns an allow/deny decision.
+    """
+
+    enabled: bool = Field(default=False, description="Enable guardrail middleware")
+    fail_closed: bool = Field(default=True, description="Block tool calls if provider errors")
+    passport: str | None = Field(default=None, description="OAP passport path or hosted agent ID")
+    provider: GuardrailProviderConfig | None = Field(default=None, description="Guardrail provider configuration")
+
+
+_guardrails_config: GuardrailsConfig | None = None
+
+
+def get_guardrails_config() -> GuardrailsConfig:
+    """Get the guardrails config, returning defaults if not loaded."""
+    global _guardrails_config
+    if _guardrails_config is None:
+        _guardrails_config = GuardrailsConfig()
+    return _guardrails_config
+
+
+def load_guardrails_config_from_dict(data: dict) -> GuardrailsConfig:
+    """Load guardrails config from a dict (called during AppConfig loading)."""
+    global _guardrails_config
+    _guardrails_config = GuardrailsConfig.model_validate(data)
+    return _guardrails_config
+
+
+def reset_guardrails_config() -> None:
+    """Reset the cached config instance. Used in tests to prevent singleton leaks."""
+    global _guardrails_config
+    _guardrails_config = None