Credence.Pattern.PreferHeredocForMultiLineDoc (credence v0.4.2)

Detects @doc, @moduledoc, and @typedoc strings that contain escaped newlines (\n) and should use heredoc syntax instead.

LLMs generate documentation as single-line strings with \n escapes because that's how Python docstrings work. In Elixir, multi-line documentation should use the heredoc (""") syntax for readability.

Bad

@doc "Finds the second largest number in a list.\nThe list must have at least two distinct values.\n"

Good

@doc """
Finds the second largest number in a list.
The list must have at least two distinct values.
"""

Auto-fix

Converts single-line @doc/@moduledoc/@typedoc strings containing \n escapes into heredoc format. The fixer preserves indentation and strips unnecessary trailing \n (since heredocs naturally end with a newline). Strings containing \"\"\" are left unchanged.