Feature: Article language, story and per-site language storage
  Articles gain a full BCP 47 language tag, a story they belong to and a
  content revision. Each site gets a language table with one default. Existing
  articles keep their ids, bodies, publication and public API. They are
  migrated without a guessed language: each gets its own story and an
  unassigned language until the owner confirms the site default.

  Background:
    Given the supported languages are "en", "en-GB", "en-US", "fr", "fr-CA", "pt", "pt-BR", "es", "de", "ar"
    And a language tag keeps its region, "pt-BR" is never reduced to "pt"
    And the domain package internal/domain/language imports only the stdlib
    And persistence is portable across SQLite, MySQL and PostgreSQL

  Scenario Outline: Language tag normalization
    When the tag "<input>" is normalized
    Then the result is "<result>"

    Examples:
      | input   | result                 |
      | en      | en                     |
      | EN      | en                     |
      | pt-br   | pt-BR                  |
      | PT_BR   | ErrInvalidLanguage     |
      | fr-ca   | fr-CA                  |
      |  fr     | fr                     |
      | e       | ErrInvalidLanguage     |
      | english | ErrInvalidLanguage     |
      | en-ZZZZ | ErrInvalidLanguage     |
      |         | ErrInvalidLanguage     |
      | xx      | ErrUnsupportedLanguage |

  Scenario Outline: Suggestion for a site's default language from Site.Locale
    Given a site whose Locale is "<locale>"
    When the default language suggestion is computed
    Then the suggestion is "<suggested>" and the substitution flag is <substituted>

    Examples:
      | locale | suggested | substituted |
      | pt-BR  | pt-BR     | false       |
      | en-GB  | en-GB     | false       |
      | fr-BE  | fr        | true        |
      | fr     | fr        | false       |
      | xx-YY  | none      | false       |
      | null   | none      | false       |

  Scenario: Migration of an existing site and its articles
    Given a database created before this change with site "default" (Locale "fr-CA") and articles 1, 2 and 3 in it, article 3 online
    When database.Migrate runs
    Then every article keeps its id, title, body, slug, is_online and timestamps
    And each article has lang "" and its own distinct story_id
    And each article has content_revision 1
    And site "default" has one site_languages row "fr-CA" with is_default true, enabled true and confirmed false
    And the migration marker for the article story backfill is recorded

  Scenario: Site without a usable locale gets no suggestion row
    Given a site with Locale null
    When database.Migrate runs
    Then the site has no site_languages row

  Scenario: Migration runs twice
    Given a migrated database
    When database.Migrate runs again
    Then no story is created or changed, no article changes and no site_languages row changes
    And the schema is identical

  Scenario: Migration is atomic
    Given a database with 3 existing articles
    And the backfill write fails while handling the second article
    When database.Migrate runs
    Then no article has a story_id and the marker is not recorded
    And the next Migrate completes the whole backfill

  Scenario: Soft-deleted articles are migrated
    Given an article that is soft-deleted before the change
    When database.Migrate runs
    Then it has its own story_id and its tombstone slug is unchanged

  Scenario: Slug is unique per site and language
    Given site 1 holds an article with slug "bonjour" in language "fr"
    When another article is created in site 1, language "fr", slug "bonjour"
    Then the write fails with a unique violation mapped to ErrSlugTaken
    When an article with slug "bonjour" is created in site 1, language "en"
    Then it is stored
    When an article with slug "bonjour" is created in site 2, language "fr"
    Then it is stored

  Scenario: Existing unassigned articles keep the current per-site slug rule
    Given two unassigned articles in site 1
    When the second is written with the first one's slug
    Then ErrSlugTaken is returned

  Scenario: One version per language in a story
    Given story 7 holds an article in language "fr"
    When a second article is stored in story 7, language "fr"
    Then the write fails with a unique violation
    When an article is stored in story 7, language "en"
    Then it is stored

  Scenario: Unassigned articles never collide on language
    Given 3 articles each with lang "" and their own story
    Then all 3 are stored

  Scenario: Creating an article before the default is confirmed
    Given site "default" has an unconfirmed suggestion "fr-CA"
    When a user creates an article with title "Bonjour le monde"
    Then the article has lang ""
    And it has a new story_id and content_revision 1

  Scenario: Creating an article after the default is confirmed
    Given site "default" has a confirmed default "fr-CA"
    When a user creates an article with title "Bonjour le monde"
    Then the article has lang "fr-CA"
    And it has a new story_id distinct from every other article

  Scenario: Create racing a confirmation never strands an article
    Given site "default" has unassigned articles
    When the default is confirmed and assigned to unassigned articles in one transaction while articles are created concurrently
    Then every article of the site ends with the confirmed default
    And no article has a different language than the confirmed default

  Scenario: Assigning a language is idempotent
    Given a site whose unassigned articles were assigned "fr-CA"
    When the assignment runs again
    Then no article changes

  Scenario Outline: Article reads expose lang and story_id
    Given article 12 with lang "<lang>" in story 5
    When it is read through "<read>"
    Then the JSON contains "lang": "<lang>" and "story_id": 5
    And every key present before this change is present with an unchanged value and type

    Examples:
      | lang  | read                                     |
      | fr-CA | GET /v1/article/12 with a valid jwt      |
      |       | GET /v1/article/12 with a valid jwt      |
      | fr-CA | GET /v1/article/ list item               |
      | fr-CA | public article read of an online article |

  Scenario: PATCH ignores lang and story_id
    When PATCH /v1/article/{id} carries "lang" or "story_id"
    Then the fields are ignored and the stored values are unchanged
    And POST /v1/article/ honours lang, story_id, source_article_id and copy only as defined in features/article_translation_create.feature
    And a POST without them behaves as before

  Scenario: Existing behaviour is unchanged
    Then the existing article, pagination, publishing and SEO tests pass without edits
    And offline articles still read as not found publicly

  Scenario: Persistence portability
    Given the repository contract cases above
    Then they pass on SQLite, MySQL 8.4, MariaDB 11 and PostgreSQL
    And no raw SQL uses a dialect-only construct