ai-runtime-guard

Implementation Reference

• src/tools/file_tools.py:123-193 (handler)

  The implementation of the delete_file tool, which includes path policy checking, budget verification, backup creation, and file deletion.

  def delete_file(path: str, ctx: Context | None = None) -> str:
      context_tokens = activate_runtime_context(ctx)
      path = str(pathlib.Path(WORKSPACE_ROOT) / path) if not os.path.isabs(path) else path
  
      try:
          path_check = check_path_policy(path, tool="delete_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)
  
          if result.allowed:
              if not os.path.exists(path):
                  append_log_entry(build_log_entry("delete_file", result, path=path, error="file not found"))
                  return f"Error: file not found: {path}"
  
              if os.path.isdir(path):
                  result = PolicyResult(
                      allowed=False,
                      reason=f"'{path}' is a directory  -  delete_file only removes individual files. Use execute_command for directory operations (note: bulk/recursive deletions are also subject to policy).",
                      decision_tier="blocked",
                      matched_rule=None,
                  )
  
          budget_fields: dict = {}
          if result.allowed:
              bytes_est = 0
              try:
                  if os.path.isfile(path):
                      bytes_est = int(os.path.getsize(path))
              except OSError:
                  bytes_est = 0
              budget_allowed, budget_reason, budget_rule, budget_fields = check_and_record_cumulative_budget(
                  tool="delete_file",
                  command=None,
                  affected_paths=[path],
                  operation_count=1,
                  bytes_estimate=bytes_est,
              )
              if not budget_allowed:
                  result = PolicyResult(
                      allowed=False,
                      reason=budget_reason or "Cumulative blast-radius budget exceeded for current scope.",
                      decision_tier="blocked",
                      matched_rule=budget_rule or "requires_simulation.cumulative_budget_exceeded",
                  )
  
          log_entry = build_log_entry("delete_file", result, path=path, **budget_fields)
          if not result.allowed:
              append_log_entry(log_entry)
              return f"[POLICY BLOCK] {result.reason}"
  
          backup_enabled = bool(POLICY.get("audit", {}).get("backup_enabled", True))
          backup_location = backup_paths([path]) if backup_enabled else ""
          if backup_location:
              log_entry["backup_location"] = backup_location
  
          append_log_entry(log_entry)
  
          try:
              os.remove(path)
          except OSError as e:
              return f"Error deleting file: {e}"
  
          return f"Successfully deleted {path}. " + (
              f"Backup saved to {backup_location}  -  the file can be recovered from there."
              if backup_location
              else "No content-change backup was needed."
          )
      finally:
          reset_runtime_context(context_tokens)