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/sandbox_config.py

@@ -0,0 +1,83 @@
+from pydantic import BaseModel, ConfigDict, Field
+
+
+class VolumeMountConfig(BaseModel):
+    """Configuration for a volume mount."""
+
+    host_path: str = Field(..., description="Path on the host machine")
+    container_path: str = Field(..., description="Path inside the container")
+    read_only: bool = Field(default=False, description="Whether the mount is read-only")
+
+
+class SandboxConfig(BaseModel):
+    """Config section for a sandbox.
+
+    Common options:
+        use: Class path of the sandbox provider (required)
+        allow_host_bash: Enable host-side bash execution for LocalSandboxProvider.
+            Dangerous and intended only for fully trusted local workflows.
+
+    AioSandboxProvider specific options:
+        image: Docker image to use (default: enterprise-public-cn-beijing.cr.volces.com/vefaas-public/all-in-one-sandbox:latest)
+        port: Base port for sandbox containers (default: 8080)
+        replicas: Maximum number of concurrent sandbox containers (default: 3). When the limit is reached the least-recently-used sandbox is evicted to make room.
+        container_prefix: Prefix for container names (default: deer-flow-sandbox)
+        idle_timeout: Idle timeout in seconds before sandbox is released (default: 600 = 10 minutes). Set to 0 to disable.
+        mounts: List of volume mounts to share directories with the container
+        environment: Environment variables to inject into the container (values starting with $ are resolved from host env)
+    """
+
+    use: str = Field(
+        ...,
+        description="Class path of the sandbox provider (e.g. deerflow.sandbox.local:LocalSandboxProvider)",
+    )
+    allow_host_bash: bool = Field(
+        default=False,
+        description="Allow the bash tool to execute directly on the host when using LocalSandboxProvider. Dangerous; intended only for fully trusted local environments.",
+    )
+    image: str | None = Field(
+        default=None,
+        description="Docker image to use for the sandbox container",
+    )
+    port: int | None = Field(
+        default=None,
+        description="Base port for sandbox containers",
+    )
+    replicas: int | None = Field(
+        default=None,
+        description="Maximum number of concurrent sandbox containers (default: 3). When the limit is reached the least-recently-used sandbox is evicted to make room.",
+    )
+    container_prefix: str | None = Field(
+        default=None,
+        description="Prefix for container names",
+    )
+    idle_timeout: int | None = Field(
+        default=None,
+        description="Idle timeout in seconds before sandbox is released (default: 600 = 10 minutes). Set to 0 to disable.",
+    )
+    mounts: list[VolumeMountConfig] = Field(
+        default_factory=list,
+        description="List of volume mounts to share directories between host and container",
+    )
+    environment: dict[str, str] = Field(
+        default_factory=dict,
+        description="Environment variables to inject into the sandbox container. Values starting with $ will be resolved from host environment variables.",
+    )
+
+    bash_output_max_chars: int = Field(
+        default=20000,
+        ge=0,
+        description="Maximum characters to keep from bash tool output. Output exceeding this limit is middle-truncated (head + tail), preserving the first and last half. Set to 0 to disable truncation.",
+    )
+    read_file_output_max_chars: int = Field(
+        default=50000,
+        ge=0,
+        description="Maximum characters to keep from read_file tool output. Output exceeding this limit is head-truncated. Set to 0 to disable truncation.",
+    )
+    ls_output_max_chars: int = Field(
+        default=20000,
+        ge=0,
+        description="Maximum characters to keep from ls tool output. Output exceeding this limit is head-truncated. Set to 0 to disable truncation.",
+    )
+
+    model_config = ConfigDict(extra="allow")