chore: remove unused private helper functions (dead code) (#3749)

These three module-private helpers have no callers anywhere in the repo
(verified by a repo-wide identifier scan + direct greps; each appears only
at its own definition):

- agents/memory/updater.py: _create_empty_memory (a no-caller wrapper around
  storage.create_empty_memory, which is used directly elsewhere)
- runtime/runs/worker.py: _extract_human_message (also drops the now-unused
  HumanMessage TYPE_CHECKING import and TYPE_CHECKING from typing)
- sandbox/tools.py: _looks_like_unsafe_cwd_target (cwd safety is enforced via
  _is_allowed_local_bash_absolute_path)

Underscore-prefixed = module-internal, so zero references is conclusive.
Route handlers and @compiles-registered functions were excluded as false
positives. Public-surface candidates are noted in the issue, not touched here.

Fixes #3748.

backend/packages/harness/deerflow/agents/memory/updater.py

@@ -38,11 +38,6 @@ _SYNC_MEMORY_UPDATER_EXECUTOR = concurrent.futures.ThreadPoolExecutor(
 atexit.register(lambda: _SYNC_MEMORY_UPDATER_EXECUTOR.shutdown(wait=False))
 
 
-def _create_empty_memory() -> dict[str, Any]:
-    """Backward-compatible wrapper around the storage-layer empty-memory factory."""
-    return create_empty_memory()
-
-
 def _save_memory_to_file(memory_data: dict[str, Any], agent_name: str | None = None, *, user_id: str | None = None) -> bool:
     """Backward-compatible wrapper around the configured memory storage save path."""
     return get_memory_storage().save(memory_data, agent_name, user_id=user_id)

backend/packages/harness/deerflow/runtime/runs/worker.py

@@ -22,13 +22,10 @@ import logging
 import os
 from dataclasses import dataclass, field
 from functools import lru_cache
-from typing import TYPE_CHECKING, Any, Literal, cast
+from typing import Any, Literal, cast
 
 from langgraph.checkpoint.base import empty_checkpoint
 
-if TYPE_CHECKING:
-    from langchain_core.messages import HumanMessage
-
 from deerflow.config.app_config import AppConfig
 from deerflow.runtime.serialization import serialize
 from deerflow.runtime.stream_bridge import StreamBridge
@@ -642,31 +639,6 @@ def _extract_llm_error_fallback_message(value: Any) -> str | None:
     return walk(value)
 
 
-def _extract_human_message(graph_input: dict) -> HumanMessage | None:
-    """Extract or construct a HumanMessage from graph_input for event recording.
-
-    Returns a LangChain HumanMessage so callers can use .model_dump() to get
-    the checkpoint-aligned serialization format.
-    """
-    from langchain_core.messages import HumanMessage
-
-    messages = graph_input.get("messages")
-    if not messages:
-        return None
-    last = messages[-1] if isinstance(messages, list) else messages
-    if isinstance(last, HumanMessage):
-        return last
-    if isinstance(last, str):
-        return HumanMessage(content=last) if last else None
-    if hasattr(last, "content"):
-        content = last.content
-        return HumanMessage(content=content)
-    if isinstance(last, dict):
-        content = last.get("content", "")
-        return HumanMessage(content=content) if content else None
-    return None
-
-
 def _unpack_stream_item(
     item: Any,
     lg_modes: list[str],

backend/packages/harness/deerflow/sandbox/tools.py

@@ -855,12 +855,6 @@ def _validate_local_bash_cwd_target(command_name: str, target: str | None, allow
             raise PermissionError(f"Unsafe working directory change in command: {command_name} {target}. Use paths under {VIRTUAL_PATH_PREFIX}")
 
 
-def _looks_like_unsafe_cwd_target(target: str | None) -> bool:
-    if target is None:
-        return False
-    return target == "-" or target.startswith(("$", "`", "~", "/", "..")) or _has_dotdot_path_segment(target)
-
-
 def _validate_local_bash_root_path_args(command_name: str, tokens: list[str], start_index: int) -> None:
     if command_name not in _LOCAL_BASH_ROOT_PATH_COMMANDS:
         return