@spec default_path() :: String.t()

Returns the default path to the project-level llm_core.toml file.

@spec delete_path(map(), [String.t()]) :: map()

Removes the value at the given key path from config.

@spec put_path(map(), [String.t()], term()) :: map()

Sets a nested value in config at the given key path.

Creates intermediate maps as needed.

@spec read(String.t() | nil) :: {:ok, map()} | {:error, term()}

Reads and decodes the TOML configuration file at path.

Returns {:ok, map()} with the parsed contents, or {:ok, %{}} if the file does not exist.

@spec update((map() -> map()), String.t() | nil) :: {:ok, map()} | {:error, term()}

Reads the config at path, applies the transformation function fun, and writes the result back.

Returns {:ok, new_config} on success.

@spec write(map(), String.t() | nil) :: :ok | {:error, term()}

Encodes map as TOML and writes it to path, creating parent directories as needed.