{
  "contract_version": "gab_005_contract_v1",
  "gab_id": "GAB-005",
  "canonical_name": "SessionStepTransition",
  "module_owner": "EdTechPlayEngine",
  "renderer_key": "text_cta",
  "required_fields": [
    "gab_id",
    "transition_id",
    "body",
    "next_action"
  ],
  "optional_fields": [
    "title",
    "hint",
    "icon_from",
    "icon_to",
    "label_from",
    "label_to",
    "progress"
  ],
  "field_types": {
    "transition_id": "string — identifiant unique de la transition (ex: 'tr-visual-memory-xxx')",
    "body": "string — phrase narrative principale (ex: 'Tu as compris la formule. Maintenant…')",
    "next_action": "string — libellé du bouton CTA (ex: 'Continuer')",
    "hint": "string|null — phrase d'accroche secondaire sous le body",
    "icon_from": "string|null — emoji représentant l'étape source (ex: '📊')",
    "icon_to": "string|null — emoji représentant l'étape cible (ex: '🃏')",
    "label_from": "string|null — libellé court de l'étape source (ex: 'Visual')",
    "label_to": "string|null — libellé court de l'étape cible (ex: 'Memory')",
    "progress": "object{current,total}|null — progression optionnelle de session"
  },
  "constraints": [
    "body est le message narratif affiché en grand — jamais vide.",
    "next_action alimente le libellé du bouton CTA structurel.",
    "icon_from / icon_to : affichés uniquement si les deux sont présents.",
    "label_from / label_to : affichés uniquement si les deux sont présents.",
    "progress si présent : object {current:integer≥1, total:integer≥1, current≤total}."
  ],
  "blocked_conditions": [
    "body absent ou vide",
    "next_action absent ou vide"
  ],
  "accessibility": [
    "keyboard_navigable",
    "focus_visible",
    "prefers_reduced_motion",
    "fallback_text"
  ],
  "qa_cases": [
    { "case": "instance conforme", "expected": "rendu complet, 0 erreur" },
    { "case": "body absent", "expected": "BLOCKED listant le champ" },
    { "case": "next_action absent", "expected": "BLOCKED listant le champ" },
    { "case": "icon_from présent mais icon_to absent", "expected": "zone from/to masquée (les deux nécessaires)" },
    { "case": "instance externe injectée", "expected": "le rendu change sans modifier le HTML" },
    { "case": "responsive 375/768/1024", "expected": "aucun débordement horizontal, flèche pivotée en colonne sur mobile" }
  ],
  "traceability": {
    "derived_from_core_gab": "GAB-005",
    "note": "Ce schema VALIDE l'instance. Le contrat pédagogique complet (input_contract/validation_logic/feedback_scoring_logic) vit dans le CORE-GAB officiel, pas ici (évite la duplication)."
  }
}