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/scripts/wizard/steps/execution.py

@@ -0,0 +1,51 @@
+"""Step: execution mode and safety-related capabilities."""
+
+from __future__ import annotations
+
+from dataclasses import dataclass
+
+from wizard.ui import ask_choice, ask_yes_no, print_header, print_info, print_warning
+
+LOCAL_SANDBOX = "deerflow.sandbox.local:LocalSandboxProvider"
+CONTAINER_SANDBOX = "deerflow.community.aio_sandbox:AioSandboxProvider"
+
+
+@dataclass
+class ExecutionStepResult:
+    sandbox_use: str
+    allow_host_bash: bool
+    include_bash_tool: bool
+    include_write_tools: bool
+
+
+def run_execution_step(step_label: str = "Step 3/4") -> ExecutionStepResult:
+    print_header(f"{step_label} · Execution & Safety")
+    print_info("Choose how much execution power DeerFlow should have in this workspace.")
+
+    options = [
+        "Local sandbox  —  fastest, uses host filesystem paths",
+        "Container sandbox  —  more isolated, requires Docker or Apple Container",
+    ]
+    sandbox_idx = ask_choice("Execution mode", options, default=0)
+    sandbox_use = LOCAL_SANDBOX if sandbox_idx == 0 else CONTAINER_SANDBOX
+
+    print()
+    if sandbox_use == LOCAL_SANDBOX:
+        print_warning(
+            "Local sandbox is convenient but not a secure shell isolation boundary."
+        )
+        print_info("Keep host bash disabled unless this is a fully trusted local workflow.")
+    else:
+        print_info("Container sandbox isolates shell execution better than host-local mode.")
+
+    include_bash_tool = ask_yes_no("Enable bash command execution?", default=False)
+    include_write_tools = ask_yes_no(
+        "Enable file write tools (write_file, str_replace)?", default=True
+    )
+
+    return ExecutionStepResult(
+        sandbox_use=sandbox_use,
+        allow_host_bash=sandbox_use == LOCAL_SANDBOX and include_bash_tool,
+        include_bash_tool=include_bash_tool,
+        include_write_tools=include_write_tools,
+    )