Separate obligation.
Preserve decoration.

ObjectDecorativeContributionEvidence {
  objectContributionSubjectRef,
  contributes: true | false,
  contributionContextRef,
  contributionBasisRef: opaque owner-defined basis,
  evidenceSourceRef,
  evidenceSourceOwnerRef,
  confidence: diagnostic only,
  provenance,
  mutationAllowed: false
}

ObjectNecessityDecorationDescriptor {
  semanticNecessityVerdict,
  decorativeContributionState,
  relationClass,

  marginalContributionRef: null,
  removalCandidateRef: null,
  redundancyScore: null,
  removalSafety: null,

  mutationAllowed: false
}

Tests cover exact 20.00 lineage, sole/shared/review/unprotected semantic rules, coverage-role conflict preservation, decorative evidence consensus/conflict/missing semantics, coexistence classes, bounded explicit selection, immutable attachment, zero metrics and 20.02–20.04 ownership firewalls.

{
  "module": "Compo 20.01",
  "name": "semantic_necessity_vs_decorative_contribution",
  "version": "1.0-canonical",
  "canonical_main_title": "Semantic necessity vs decorative contribution",
  "topic": "20_ЭКОНОМИЯ_И_УДАЛЕНИЕ_ЛИШНЕГО",
  "scope": "DECLARED_MODEL_SCOPED_SEMANTIC_NECESSITY_JUDGEMENT_AND_OWNER_QUALIFIED_DECORATIVE_CONTRIBUTION_RESOLUTION_ONLY_WITHOUT_ABLATION_REMOVAL_REDUNDANCY_SCORING_OR_METRICRESULT",
  "main_topic_contract": {
    "topic_title": "Экономия и удаление лишнего",
    "topic_goal": "Проверяет необходимость каждого элемента через semantic necessity и marginal contribution. Позволяет предлагать удаление лишнего без разрушения обязательного content.",
    "expected_output": "ObjectContributionDescriptor, redundancy score, removal candidates",
    "planned_files": [
      "20.00 Necessity/redundancy model",
      "20.01 Semantic necessity vs decorative contribution",
      "20.02 Marginal contribution / ablation",
      "20.03 Removal candidates and clutter reduction",
      "20.04 Scoring and tests"
    ]
  },
  "ownership": {
    "owner": "Compo20.01",
    "owns": [
      "ObjectSemanticNecessityVerdict taxonomy",
      "ObjectSemanticNecessityDescriptor",
      "ObjectDecorativeContributionEvidence adapter",
      "ObjectDecorativeContributionResolution",
      "ObjectNecessityDecorationRelationClass taxonomy",
      "ObjectNecessityDecorationDescriptor",
      "ObjectSemanticDecorationSelectionPolicy",
      "ObjectSemanticDecorationSet",
      "ObjectSemanticNecessityDecorationAttachment",
      "declared-model-scoped necessity judgement from exact 20.00 requirement/protection/coverage declarations",
      "owner-qualified decorative-contribution evidence resolution",
      "identity/status/provenance rules for Topic20 semantic-vs-decorative layer",
      "non-mutating correction request for 20.01 evidence/lineage errors"
    ],
    "does_not_own": [
      "20.00 subject/requirement/coverage/hypothesis/root model identity",
      "semantic meaning or task importance inference outside explicit 20.00 declarations",
      "decorative appearance measurement or aesthetic value inference",
      "marginal contribution / ablation and ObjectContributionDescriptor — Compo20.02",
      "removal candidate generation / clutter reduction — Compo20.03",
      "redundancy score / MetricResult scoring — Compo20.04",
      "Topic19 observed visual hierarchy",
      "Topic18 declared hierarchy/subordination",
      "Compo13 dominance / focal ranking",
      "Compo4 visual mass",
      "global beautyScore",
      "final-layout ranking",
      "foreign geometry/content/style mutation"
    ]
  },
  "consumes": [
    "valid Compo20.00 ObjectContributionSystemSeed lineage",
    "valid Compo20.00 ObjectContributionModel and ObjectContributionSubjectSet",
    "exact Compo20.00 ObjectContributionRequirement[] records named by model.requirementRefs",
    "exact Compo20.00 ObjectContributionCoverageClaim[] records named by model.coverageClaimRefs",
    "explicit owner-qualified decorative contribution evidence",
    "explicit ObjectSemanticDecorationSelectionPolicy"
  ],
  "provides": [
    "ObjectSemanticNecessityDescriptor[]",
    "ObjectDecorativeContributionResolution[]",
    "ObjectNecessityDecorationDescriptor[]",
    "ObjectSemanticDecorationSet",
    "ObjectSemanticNecessityDecorationAttachment"
  ],
  "owns_metrics": [],
  "metric_ownership_note": "20.01 emits categorical semantic-necessity and decorative-contribution descriptors only. It owns no redundancy score, no ablation score, no MetricResult and no independent numeric vote.",
  "semantic_necessity_verdict_taxonomy": {
    "LOCALLY_REQUIRED": "Within this exact declared model snapshot, the subject is the SOLE_DECLARED_PROVIDER of at least one REQUIRED_PRESENCE requirement. This is local evidence, not universal irreplaceability.",
    "UNRESOLVED": "The subject touches required/review-protected coverage, but the declarations do not prove individual necessity or safe substitution.",
    "NOT_ESTABLISHED_IN_DECLARED_MODEL": "No current declaration proves individual semantic necessity. This never means safe to remove."
  },
  "semantic_necessity_rules": [
    "REQUIRED_PRESENCE + SOLE_DECLARED_PROVIDER => LOCALLY_REQUIRED",
    "REQUIRED_PRESENCE + CO_PROVIDER/SUPPORTING/UNSPECIFIED => UNRESOLVED",
    "REVIEW_REQUIRED + any valid coverage role => UNRESOLVED",
    "NO_DECLARED_PROTECTION alone cannot establish necessity",
    "no coverage claim => NOT_ESTABLISHED_IN_DECLARED_MODEL",
    "conflicting coverage roles for the same exact subject+requirement => N_A",
    "LOCALLY_REQUIRED is snapshot-local and does not prohibit future substitute discovery"
  ],
  "decorative_contribution_evidence_schema": {
    "objectDecorativeContributionEvidenceRef": "stable identity",
    "scopeRef": "Topic20 scope",
    "objectContributionSubjectRef": "exact 20.00 subject",
    "contributes": "explicit boolean owner declaration",
    "contributionContextRef": "exact context under which the declaration applies",
    "contributionBasisRef": "opaque owner-defined basis; 20.01 does not infer appearance semantics",
    "evidenceSourceRef": "explicit source",
    "evidenceSourceOwnerRef": "owner",
    "confidence": "finite [0,1] or null; diagnostic only",
    "provenance": "canonical provenance",
    "status": "OK|INVALID",
    "mutationAllowed": false
  },
  "decorative_resolution_schema": {
    "objectDecorativeContributionResolutionRef": "stable identity",
    "scopeRef": "scope",
    "objectContributionSubjectRef": "exact subject",
    "contributionContextRef": "exact selection context",
    "evidenceRefs[]": "actual evidence lineage",
    "decorativeContributionState": "DECLARED_PRESENT|DECLARED_ABSENT|null",
    "status": "OK|N_A|INVALID",
    "reasonCode": "CONSENSUS|MISSING_EVIDENCE|CONFLICT|INVALID_EVIDENCE|LINEAGE_MISMATCH",
    "confidence": "diagnostic aggregate or null; never a score",
    "mutationAllowed": false
  },
  "necessity_decoration_descriptor_schema": {
    "objectNecessityDecorationDescriptorRef": "stable identity",
    "objectContributionSubjectRef": "exact 20.00 subject",
    "semanticNecessityDescriptorRef": "exact 20.01 semantic descriptor",
    "decorativeContributionResolutionRef": "exact 20.01 decorative resolution",
    "semanticNecessityVerdict": "LOCALLY_REQUIRED|UNRESOLVED|NOT_ESTABLISHED_IN_DECLARED_MODEL|null",
    "decorativeContributionState": "DECLARED_PRESENT|DECLARED_ABSENT|null",
    "relationClass": "SEMANTIC_REQUIRED_AND_DECORATIVE|SEMANTIC_REQUIRED_DECORATIVE_ABSENT|SEMANTIC_NOT_ESTABLISHED_DECORATIVE_PRESENT|SEMANTIC_NOT_ESTABLISHED_DECORATIVE_ABSENT|SEMANTIC_UNRESOLVED|null",
    "marginalContributionRef": null,
    "removalCandidateRef": null,
    "redundancyScore": null,
    "removalSafety": null,
    "status": "OK|N_A|INVALID",
    "mutationAllowed": false,
    "firewall": "Semantic necessity and decorative contribution are independent axes. They may coexist. Neither axis alone decides removal."
  },
  "selection_policy_schema": {
    "selectionMode": "EXPLICIT_SUBJECTS_ONLY",
    "decorativeEvidenceSelectionMode": "EXACT_SUBJECT_AND_CONTEXT_ONLY",
    "duplicatePolicy": "DEDUP_EXACT_IDENTITY",
    "coverageRoleConflictPolicy": "N_A_NO_GUESS",
    "missingDecorativeEvidencePolicy": "N_A_NO_GUESS",
    "maxSubjects": "1..512",
    "overflowPolicy": "N_A_NO_TRUNCATION",
    "autoDecorativeInference": false,
    "autoRemovalDecision": false,
    "autoAblation": false
  },
  "status_policy": {
    "invalidRootModelOrSubjectSet": "INVALID or N_A matching upstream availability",
    "rootLineageMismatch": "N_A",
    "unknownSelectedSubject": "N_A",
    "coverageRoleConflict": "N_A",
    "soleRequiredCoverage": "OK + LOCALLY_REQUIRED",
    "sharedOrReviewProtectedCoverage": "OK + UNRESOLVED",
    "noNecessityEvidence": "OK + NOT_ESTABLISHED_IN_DECLARED_MODEL",
    "missingDecorativeEvidence": "N_A",
    "decorativeEvidenceConflict": "N_A",
    "invalidDecorativeEvidence": "INVALID",
    "selectionOverflow": "N_A; no truncation",
    "N_A_not_zero": true
  },
  "critical_firewalls": [
    "20.01 owns no MetricResult and no independent numeric vote",
    "LOCALLY_REQUIRED is local to exact declared model/snapshot",
    "LOCALLY_REQUIRED != universally irreplaceable",
    "NOT_ESTABLISHED_IN_DECLARED_MODEL != unnecessary",
    "NOT_ESTABLISHED_IN_DECLARED_MODEL != safe to remove",
    "UNRESOLVED != zero necessity",
    "decorative contribution != redundancy",
    "decorative contribution != aesthetic score",
    "decorative contribution may coexist with semantic necessity",
    "declared decorative absence != zero marginal contribution",
    "SOLE_DECLARED_PROVIDER + REQUIRED_PRESENCE is local necessity evidence only",
    "CO_PROVIDER != redundant",
    "SUPPORTING != removable",
    "NO_DECLARED_PROTECTION != safe to remove",
    "low Topic19 hierarchy rank != not necessary",
    "low visual mass != not necessary",
    "no ablation in 20.01",
    "no ObjectContributionDescriptor in 20.01",
    "no removal candidates in 20.01",
    "no redundancy score in 20.01",
    "N_A != 0",
    "descriptor != score",
    "local != global",
    "correction request != foreign mutation"
  ],
  "IDEAS_REFS": [
    "IDEA-01 study agreement between declared semantic necessity and human removal judgements",
    "IDEA-02 study objects that are simultaneously semantically required and decoratively contributive",
    "IDEA-03 collect false assumptions that decorative objects are redundant",
    "IDEA-04 compare shared-provider declarations with later ablation outcomes",
    "IDEA-05 study owner disagreement on decorative contribution without confidence winner"
  ],
  "DATA_CAPTURE": [
    "scopeRef",
    "snapshotRef",
    "objectContributionSystemSeedRef",
    "objectContributionModelRef",
    "selectedSubjectRefs[]",
    "semanticNecessityDescriptorRefs[]",
    "necessityVerdictBySubject",
    "necessityBasisRequirementRefsBySubject",
    "necessityBasisCoverageClaimRefsBySubject",
    "decorativeEvidenceRefs[]",
    "decorativeContributionResolutionRefs[]",
    "decorativeStateBySubject",
    "necessityDecorationDescriptorRefs[]",
    "relationClassBySubject",
    "status",
    "reasonCode"
  ],
  "DEFERRED_SEMANTIC_INPUTS": [
    "20.02 marginal contribution / ablation",
    "20.02 ObjectContributionDescriptor",
    "20.03 removal candidate generation and clutter reduction",
    "20.04 redundancy score and MetricResult scoring",
    "global composition quality",
    "final-layout ranking"
  ],
  "HUMAN_FEEDBACK_HOOKS": [
    "correct requirement protection declaration",
    "correct coverage role",
    "mark coverage role conflict real",
    "correct decorative contribution evidence",
    "mark decorative evidence conflict real",
    "correct decorative evidence context",
    "correct decorative evidence owner",
    "explain semantic necessity that is not represented by current requirement model"
  ],
  "CONFLICT_PRIORITY_ASSUMPTIONS": [
    "coverage claim serialization order has no priority",
    "decorative evidence source order has no priority",
    "confidence does not choose a decorative evidence winner",
    "requirement kind order does not define importance",
    "LOCALLY_REQUIRED/UNRESOLVED/NOT_ESTABLISHED labels are logic states, not quality ranks",
    "module execution order does not imply semantic priority"
  ],
  "LAB_HOOKS": [
    "semantic necessity versus ablation study",
    "decorative contribution perception study",
    "shared-provider necessity study",
    "declared-protection robustness study",
    "false-removal study for decorative-but-required objects",
    "human correction reason taxonomy"
  ],
  "topic20ProgressAfterThisModule": "2/5 local",
  "next_module": "Compo 20.02 — Marginal contribution / ablation",
  "hard_stop": "Do not implement 20.02, 20.03 or 20.04 in this file."
}