{
  "$schema": "https://json-schema.org/draft/2020-12/schema",
  "$id": "ucwm/schemas/constraints.json",
  "title": "Constraint",
  "description": "The core reasoning currency of UCWM. An explicit relation, restriction, incompatibility, requirement, or preference involving objects and/or facets.",
  "type": "object",
  "required": ["constraint_id", "constraint_type", "argument_refs", "polarity", "strength", "status", "source_module"],
  "additionalProperties": false,
  "properties": {
    "constraint_id": {
      "type": "string",
      "description": "Unique identifier. Format: C{sequence} e.g. C1, C14"
    },
    "constraint_type": {
      "type": "string",
      "description": "Named relation type. Implementors should define allowed values per domain.",
      "examples": [
        "before",
        "after",
        "during",
        "causes",
        "enables",
        "blocks",
        "same_entity",
        "not_same_entity",
        "owns",
        "transfers",
        "inside",
        "outside",
        "adjacent",
        "quantity_equals",
        "quantity_sum",
        "quantity_difference",
        "quantity_product",
        "quantity_greater",
        "quantity_less",
        "truth_value",
        "implies",
        "negates",
        "contradicts",
        "prerequisite",
        "goal",
        "has_role"
      ]
    },
    "argument_refs": {
      "type": "array",
      "items": { "type": "string" },
      "minItems": 1,
      "description": "Ordered list of object_ids or facet_ids this constraint relates. Order is significant for asymmetric relations."
    },
    "polarity": {
      "type": "string",
      "enum": ["positive", "negative"],
      "description": "Whether this constraint asserts or denies the relation."
    },
    "strength": {
      "type": "string",
      "enum": ["hard", "soft", "probabilistic", "defeasible"],
      "description": "hard=must hold; soft=preferred; probabilistic=holds with stated probability; defeasible=default, retractable by new evidence"
    },
    "probability": {
      "type": "number",
      "minimum": 0.0,
      "maximum": 1.0,
      "description": "Required when strength=probabilistic."
    },
    "status": {
      "type": "string",
      "enum": ["unresolved", "resolved", "contradicted", "suspended"],
      "description": "Resolver lifecycle status.",
      "default": "unresolved"
    },
    "expression": {
      "type": "string",
      "description": "Optional human-readable or formal logic expression of the constraint. Informational; not authoritative.",
      "examples": [
        "before(E1, E2)",
        "quantity(Q1) = quantity(Q2) - 3",
        "owner(O3) = Entity_Alice"
      ]
    },
    "confidence": {
      "type": "number",
      "minimum": 0.0,
      "maximum": 1.0,
      "description": "Confidence that this constraint is correctly extracted."
    },
    "contradicted_by_refs": {
      "type": "array",
      "items": { "type": "string" },
      "description": "constraint_ids that contradict this one. Populated by the resolver.",
      "default": []
    },
    "supports_refs": {
      "type": "array",
      "items": { "type": "string" },
      "description": "constraint_ids that reinforce this one.",
      "default": []
    },
    "source_module": {
      "type": "string",
      "description": "Specialist or module that emitted this constraint."
    },
    "provenance_refs": {
      "type": "array",
      "items": { "type": "string" },
      "default": []
    }
  },
  "examples": [
    {
      "constraint_id": "C1",
      "constraint_type": "owns",
      "argument_refs": ["E1", "O_apples", "Q1"],
      "polarity": "positive",
      "strength": "hard",
      "status": "resolved",
      "expression": "owns(Alice, apples, count=5) at t0",
      "confidence": 0.98,
      "source_module": "ownership_specialist",
      "contradicted_by_refs": [],
      "supports_refs": [],
      "provenance_refs": ["P1"]
    },
    {
      "constraint_id": "C2",
      "constraint_type": "before",
      "argument_refs": ["EV_initial_possession", "EV_transfer"],
      "polarity": "positive",
      "strength": "hard",
      "status": "resolved",
      "expression": "before(E_initial_possession, E_transfer)",
      "confidence": 0.99,
      "source_module": "temporal_specialist",
      "contradicted_by_refs": [],
      "supports_refs": [],
      "provenance_refs": ["P2"]
    },
    {
      "constraint_id": "C3",
      "constraint_type": "quantity_difference",
      "argument_refs": ["Q_alice_final", "Q1", "Q2"],
      "polarity": "positive",
      "strength": "hard",
      "status": "resolved",
      "expression": "quantity(Q_alice_final) = quantity(Q1) - quantity(Q2)",
      "confidence": 0.99,
      "source_module": "quantity_specialist",
      "contradicted_by_refs": [],
      "supports_refs": [],
      "provenance_refs": ["P3"]
    }
  ]
}