@spec clear_conflicting_url_slugs(String.t(), String.t()) :: [
  {String.t(), String.t()}
]

Clears custom url_slugs that conflict with a given post slug.

@spec clear_url_slug_from_post(String.t(), String.t(), String.t()) :: [String.t()]

Clears a specific url_slug from all translations of a single post (DB-only).

@spec generate_unique_slug(String.t(), String.t(), String.t() | nil, keyword()) ::
  {:ok, String.t()} | {:error, :invalid_format | :reserved_language_code}

Generates a unique slug based on title and optional preferred slug.

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

Returns the HTML5 pattern attribute source matching the active slug style.

Keeps the editor's url_slug input client-side validation in sync with the server-side validate_url_slug/4 — ASCII for :transliterate/:ascii, Unicode letters/numbers for :unicode. Without this the input would reject a valid Unicode slug the server accepts.

@spec matches_shape?(any()) :: boolean()

Returns true when the slug matches the active style's shape pattern.

Style-aware companion for group-slug validation in the facade.

@spec slug_exists?(String.t(), String.t()) :: boolean()

Checks if a slug already exists within the given publishing group (DB-only).

@spec slug_style() :: :transliterate | :unicode | :ascii

Returns the configured slug style as an atom.

:transliterate (default) | :unicode | :ascii. Controlled by the publishing_slug_style setting; falls back to :transliterate on any error.

@spec slugify(
  String.t() | nil,
  keyword()
) :: String.t()

Converts text into a slug honoring the configured (or given) style.

• :transliterate — map Cyrillic + strip Latin diacritics to ASCII, then [a-z0-9-]. Default; keeps URLs ASCII and validation simple.
• :unicode — keep letters/numbers from any script (e.g. привет-мир).
• :ascii — legacy behavior: strip everything non-ASCII.

Pass style: :unicode to override the setting (used by tests).

@spec valid_slug?(String.t()) :: boolean()

Validates whether the given string is a slug and not a reserved language code.

@spec validate_slug(String.t()) ::
  {:ok, String.t()} | {:error, :invalid_format | :reserved_language_code}

Validates whether the given string is a valid slug format and not a reserved language code.

@spec validate_url_slug(String.t(), String.t(), String.t(), String.t() | nil) ::
  {:ok, String.t()} | {:error, atom()}

Validates a per-language URL slug for uniqueness within a group+language combination.