feat(langchain_v1): add deepagents middleware

libs/langchain_v1/langchain/agents/_internal/file_utils.py

@@ -0,0 +1,283 @@
+"""Shared utility functions for file operations in middleware."""
+
+from __future__ import annotations
+
+import os
+from datetime import datetime, timezone
+from typing import TYPE_CHECKING, Literal
+
+from typing_extensions import TypedDict
+
+if TYPE_CHECKING:
+    from collections.abc import Sequence
+
+
+class FileData(TypedDict):
+    """Data structure for storing file contents with metadata."""
+
+    content: list[str]
+    """Lines of the file."""
+
+    created_at: str
+    """ISO 8601 timestamp of file creation."""
+
+    modified_at: str
+    """ISO 8601 timestamp of last modification."""
+
+
+def file_data_reducer(
+    left: dict[str, FileData] | None, right: dict[str, FileData | None]
+) -> dict[str, FileData]:
+    """Custom reducer that merges file updates.
+
+    Args:
+        left: Existing files dict.
+        right: New files dict to merge (None values delete files).
+
+    Returns:
+        Merged dict where right overwrites left for matching keys.
+    """
+    if left is None:
+        # Filter out None values when initializing
+        return {k: v for k, v in right.items() if v is not None}
+
+    # Merge, filtering out None values (deletions)
+    result = {**left}
+    for k, v in right.items():
+        if v is None:
+            result.pop(k, None)
+        else:
+            result[k] = v
+    return result
+
+
+def validate_path(path: str, *, allowed_prefixes: Sequence[str] | None = None) -> str:
+    """Validate and normalize file path for security.
+
+    Args:
+        path: The path to validate.
+        allowed_prefixes: Optional list of allowed path prefixes.
+
+    Returns:
+        Normalized canonical path.
+
+    Raises:
+        ValueError: If path contains traversal sequences or violates prefix rules.
+    """
+    # Reject paths with traversal attempts
+    if ".." in path or path.startswith("~"):
+        msg = f"Path traversal not allowed: {path}"
+        raise ValueError(msg)
+
+    # Normalize path (resolve ., //, etc.)
+    normalized = os.path.normpath(path)
+
+    # Convert to forward slashes for consistency
+    normalized = normalized.replace("\\", "/")
+
+    # Ensure path starts with /
+    if not normalized.startswith("/"):
+        normalized = f"/{normalized}"
+
+    # Check allowed prefixes if specified
+    if allowed_prefixes is not None and not any(
+        normalized.startswith(prefix) for prefix in allowed_prefixes
+    ):
+        msg = f"Path must start with one of {allowed_prefixes}: {path}"
+        raise ValueError(msg)
+
+    return normalized
+
+
+def format_content_with_line_numbers(
+    content: str | list[str],
+    *,
+    format_style: Literal["pipe", "tab"] = "pipe",
+    start_line: int = 1,
+) -> str:
+    r"""Format file content with line numbers.
+
+    Args:
+        content: File content as string or list of lines.
+        format_style: "pipe" for "1|content" or "tab" for "     1\tcontent".
+        start_line: Starting line number.
+
+    Returns:
+        Formatted content with line numbers.
+    """
+    if isinstance(content, str):
+        lines = content.split("\n")
+        # Remove trailing empty line from split
+        if lines and lines[-1] == "":
+            lines = lines[:-1]
+    else:
+        lines = content
+
+    if format_style == "pipe":
+        return "\n".join(f"{i + start_line}|{line}" for i, line in enumerate(lines))
+
+    return "\n".join(f"{i + start_line:6d}\t{line[:2000]}" for i, line in enumerate(lines))
+
+
+def apply_string_replacement(
+    content: str,
+    old_string: str,
+    new_string: str,
+    *,
+    replace_all: bool = False,
+) -> tuple[str, int]:
+    """Apply string replacement to content.
+
+    Args:
+        content: Original content.
+        old_string: String to replace.
+        new_string: Replacement string.
+        replace_all: If True, replace all occurrences. Otherwise, replace first.
+
+    Returns:
+        Tuple of (new_content, replacement_count).
+    """
+    if replace_all:
+        count = content.count(old_string)
+        new_content = content.replace(old_string, new_string)
+    else:
+        count = 1
+        new_content = content.replace(old_string, new_string, 1)
+
+    return new_content, count
+
+
+def create_file_data(
+    content: str | list[str],
+    *,
+    created_at: str | None = None,
+) -> FileData:
+    """Create a FileData object from content.
+
+    Args:
+        content: File content as string or list of lines.
+        created_at: Optional creation timestamp. If None, uses current time.
+
+    Returns:
+        FileData object.
+    """
+    lines = content.split("\n") if isinstance(content, str) else content
+
+    now = datetime.now(timezone.utc).isoformat()
+
+    return {
+        "content": lines,
+        "created_at": created_at or now,
+        "modified_at": now,
+    }
+
+
+def update_file_data(
+    file_data: FileData,
+    content: str | list[str],
+) -> FileData:
+    """Update a FileData object with new content.
+
+    Args:
+        file_data: Existing FileData object.
+        content: New file content as string or list of lines.
+
+    Returns:
+        Updated FileData object with new modified_at timestamp.
+    """
+    lines = content.split("\n") if isinstance(content, str) else content
+
+    now = datetime.now(timezone.utc).isoformat()
+
+    return {
+        "content": lines,
+        "created_at": file_data["created_at"],
+        "modified_at": now,
+    }
+
+
+def file_data_to_string(file_data: FileData) -> str:
+    """Convert FileData to plain string content.
+
+    Args:
+        file_data: FileData object.
+
+    Returns:
+        File content as string.
+    """
+    return "\n".join(file_data["content"])
+
+
+def list_directory(files: dict[str, FileData], path: str) -> list[str]:
+    """List files in a directory.
+
+    Args:
+        files: Files dict mapping paths to FileData.
+        path: Normalized directory path.
+
+    Returns:
+        Sorted list of file paths in the directory.
+    """
+    # Ensure path ends with / for directory matching
+    dir_path = path if path.endswith("/") else f"{path}/"
+
+    matching_files = []
+    for file_path in files:
+        if file_path.startswith(dir_path):
+            # Get relative path from directory
+            relative = file_path[len(dir_path) :]
+            # Only include direct children (no subdirectories)
+            if "/" not in relative:
+                matching_files.append(file_path)
+
+    return sorted(matching_files)
+
+
+def check_empty_content(content: str) -> str | None:
+    """Check if file content is empty and return warning message.
+
+    Args:
+        content: File content.
+
+    Returns:
+        Warning message if empty, None otherwise.
+    """
+    if not content or content.strip() == "":
+        return "System reminder: File exists but has empty contents"
+    return None
+
+
+def has_memories_prefix(file_path: str) -> bool:
+    """Check if file path has the memories prefix.
+
+    Args:
+        file_path: File path.
+
+    Returns:
+        True if file path has the memories prefix, False otherwise.
+    """
+    return file_path.startswith("/memories/")
+
+
+def append_memories_prefix(file_path: str) -> str:
+    """Append the memories prefix to a file path.
+
+    Args:
+        file_path: File path.
+
+    Returns:
+        File path with the memories prefix.
+    """
+    return f"/memories{file_path}"
+
+
+def strip_memories_prefix(file_path: str) -> str:
+    """Strip the memories prefix from a file path.
+
+    Args:
+        file_path: File path.
+
+    Returns:
+        File path without the memories prefix.
+    """
+    return file_path.replace("/memories", "")

libs/langchain_v1/langchain/agents/middleware/__init__.py

@@ -4,15 +4,17 @@
     ClearToolUsesEdit,
     ContextEditingMiddleware,
 )
+from .filesystem import FilesystemMiddleware
 from .human_in_the_loop import (
     HumanInTheLoopMiddleware,
     InterruptOnConfig,
 )
 from .model_call_limit import ModelCallLimitMiddleware
 from .model_fallback import ModelFallbackMiddleware
 from .pii import PIIDetectionError, PIIMiddleware
+from .subagents import SubAgentMiddleware
 from .summarization import SummarizationMiddleware
-from .todo import TodoListMiddleware
+from .todo_list import TodoListMiddleware
 from .tool_call_limit import ToolCallLimitMiddleware
 from .tool_emulator import LLMToolEmulator
 from .tool_selection import LLMToolSelectorMiddleware
@@ -36,6 +38,7 @@
     "AgentState",
     "ClearToolUsesEdit",
     "ContextEditingMiddleware",
+    "FilesystemMiddleware",
     "HumanInTheLoopMiddleware",
     "InterruptOnConfig",
     "LLMToolEmulator",
@@ -46,6 +49,7 @@
     "ModelResponse",
     "PIIDetectionError",
     "PIIMiddleware",
+    "SubAgentMiddleware",
     "SummarizationMiddleware",
     "TodoListMiddleware",
     "ToolCallLimitMiddleware",