read_file

Instructions

Implementation Reference

• src/tools/file_tools.py:20-45 (handler)

  The core read_file function that enforces path policy, logs the action, and reads the file contents.

  def read_file(path: str, ctx: Context | None = None) -> str:
      """Read a text file from the workspace after path-policy enforcement."""
      context_tokens = activate_runtime_context(ctx)
      path = str(pathlib.Path(WORKSPACE_ROOT) / path) if not os.path.isabs(path) else path
  
      try:
          refresh_policy_if_changed()
          path_check = check_path_policy(path, tool="read_file")
          if path_check:
              result = PolicyResult(allowed=False, reason=path_check[0], decision_tier="blocked", matched_rule=path_check[1])
          else:
              result = PolicyResult(allowed=True, reason="allowed", decision_tier="allowed", matched_rule=None)
  
          append_log_entry(build_log_entry("read_file", result, path=path))
          if not result.allowed:
              return f"[POLICY BLOCK] {result.reason}"
  
          try:
              with open(path, "r", errors="replace") as f:
                  return f.read()
          except FileNotFoundError:
              return f"Error: file not found: {path}"
          except OSError as e:
              return f"Error reading file: {e}"
      finally:
          reset_runtime_context(context_tokens)

• src/server.py:21-31 (registration)

  Registers read_file as an MCP tool by passing it to mcp.tool().

  for tool in [
      server_info,
      restore_backup,
      execute_command,
      read_file,
      write_file,
      edit_file,
      delete_file,
      list_directory,
  ]:
      mcp.tool()(tool)

• src/tools/__init__.py:1-14 (registration)

  Exports read_file in the public tools package __all__.

  from .command_tools import execute_command, server_info
  from .file_tools import delete_file, edit_file, list_directory, read_file, write_file
  from .restore_tools import restore_backup
  
  __all__ = [
      "server_info",
      "execute_command",
      "read_file",
      "write_file",
      "edit_file",
      "delete_file",
      "list_directory",
      "restore_backup",
  ]

• src/mcp_config_manager.py:30-39 (helper)

  Lists read_file as one of the AIRG MCP tools in the config manager.

  AIRG_MCP_TOOLS = [
      "server_info",
      "restore_backup",
      "execute_command",
      "read_file",
      "write_file",
      "edit_file",
      "delete_file",
      "list_directory",
  ]

• src/airg_hook.py:345-375 (helper)

  AIRG hook handling 'beforereadfile' event for native Read tool interception, redirecting users to use mcp__ai-runtime-guard__read_file.

  if hook_event == "beforereadfile":
      file_path = str(payload.get("file_path", "")).strip()
      lowered = file_path.lower()
      violated = _blocked_by_policy(file_path) if file_path else None
      if not violated and lowered:
          if any(lowered.endswith(suffix) for suffix in SENSITIVE_READ_SUFFIXES) or "/secrets/" in lowered:
              violated = "sensitive read target"
      if violated:
          reason = f"AIRG policy: read blocked ({violated}). Use AIRG MCP tools within allowed path policy."
          _append_log(
              _build_activity_entry(
                  payload=payload,
                  tool_name="Read",
                  allowed=False,
                  event="hook_before_read_blocked",
                  hook_reason=reason,
                  hook_detail=file_path,
              )
          )
          return _emit_deny(reason, hook_event_name="beforeReadFile")
      _append_log(
          _build_activity_entry(
              payload=payload,
              tool_name="Read",
              allowed=True,
              event="hook_before_read_allowed",
              hook_reason="read_allowed",
              hook_detail=file_path,
          )
      )
      return _allow()