Multi-Tier Evidence Aggregation

Supply Chain Evidence Flow

Modern complex systems involve evidence contributions from multiple organizational tiers, each with different capabilities, tools, and responsibilities:

Hierarchical Evidence Structure

Tier 0 (System Integrator)
├── System requirements and safety goals
├── Integration test results and validation
├── Supplier management and qualification
└── Final safety case and compliance documentation

Tier 1 (Major Suppliers)
├── Component specifications and interfaces
├── Component validation and verification
├── Sub-supplier coordination and evidence aggregation
└── Component safety analysis and risk assessment

Tier 2 (Component Suppliers)
├── Implementation details and unit tests
├── Component-level design documentation
├── Manufacturing and quality control evidence
└── Technology-specific validation results

Tier 3 (Technology Providers)
├── Algorithm specifications and performance data
├── Technology validation and characterization
├── Intellectual property and licensing documentation
└── Reference implementations and benchmarks

Evidence Responsibility Matrix

Different tiers contribute different types of evidence:

Evidence Type	Tier 0	Tier 1	Tier 2	Tier 3
System Requirements	Creates	Refines	Implements	References
Interface Specifications	Reviews	Creates	Implements	Supports
Component Testing	Integrates	Validates	Executes	Provides tools
Safety Analysis	Owns	Contributes	Supports	Characterizes
Compliance Documentation	Compiles	Contributes	Supports	Provides data

TRF Supply Chain Model

Evidence Package Composition

TRF enables systematic evidence aggregation through structured packaging:

{
  "system_evidence_package": {
    "integrator_contributions": [
      "system_requirements.twpack",
      "integration_tests.twpack",
      "safety_case.twpack"
    ],
    "tier1_contributions": [
      "ecu_specification.twpack",
      "software_validation.twpack",
      "supplier_evidence.twpack"
    ],
    "tier2_contributions": [
      "sensor_implementation.twpack",
      "actuator_testing.twpack",
      "manufacturing_evidence.twpack"
    ],
    "tier3_contributions": [
      "algorithm_validation.twpack",
      "chip_characterization.twpack",
      "reference_data.twpack"
    ]
  }
}

Cross-Tier Artifact Relationships

TRF maintains traceability links across organizational boundaries:

{
  "cross_tier_links": [
    {
      "from": "tier0:sys_req_001",
      "to": "tier1:comp_spec_001",
      "type": "allocates_to",
      "organization_boundary": true
    },
    {
      "from": "tier1:comp_spec_001",
      "to": "tier2:impl_unit_001",
      "type": "implements",
      "organization_boundary": true
    },
    {
      "from": "tier2:impl_unit_001",
      "to": "tier3:algorithm_001",
      "type": "uses",
      "organization_boundary": true
    }
  ]
}

Evidence Aggregation Workflows

Systematic processes for collecting and validating multi-tier evidence:

# Tier 3: Technology provider creates base evidence
tw create tech_validation.twpack --artifacts algorithms/ --domain ai_ml

# Tier 2: Component supplier integrates tech evidence
tw merge component_impl.twpack tech_validation.twpack --output integrated.twpack

# Tier 1: Major supplier validates complete component
tw validate integrated.twpack --check-completeness --domain automotive

# Tier 0: System integrator aggregates all evidence
tw aggregate system_evidence.twpack tier1_*.twpack --output final_submission.twpack

Evidence Qualification and Trust

Supplier Qualification

TRF supports systematic supplier evidence qualification:

{
  "supplier_qualification": {
    "organization": "tier2_sensor_supplier",
    "qualification_level": "automotive_qualified",
    "evidence_standards": ["ISO26262", "ASPICE"],
    "tool_chain_qualified": true,
    "process_audit_date": "2024-01-15",
    "evidence_quality_score": 0.95,
    "previous_submissions": [
      "project_a_evidence.twpack",
      "project_b_evidence.twpack"
    ]
  }
}

Evidence Provenance Tracking

Complete audit trail for evidence contributions:

{
  "provenance_chain": [
    {
      "organization": "tier3_ai_vendor",
      "artifact": "model:perception_v2.1",
      "timestamp": "2024-01-10T14:30:00Z",
      "signature": "tier3_development_signature",
      "validation_status": "internal_validation_complete"
    },
    {
      "organization": "tier2_component_supplier",
      "artifact": "component:perception_ecu",
      "timestamp": "2024-01-15T09:45:00Z",
      "signature": "tier2_integration_signature",
      "validation_status": "component_validation_complete",
      "incorporates": ["model:perception_v2.1"]
    },
    {
      "organization": "tier1_system_supplier",
      "artifact": "system:adas_module",
      "timestamp": "2024-01-20T16:20:00Z",
      "signature": "tier1_system_signature",
      "validation_status": "system_validation_complete",
      "incorporates": ["component:perception_ecu"]
    }
  ]
}

Trust Verification

Multi-party verification of evidence integrity:

# Verify signatures from all contributors
tw verify-chain system_evidence.twpack --require-all-signatures

# Check evidence completeness across tiers
tw coverage-analysis system_evidence.twpack --cross-tier

# Validate supplier qualifications
tw validate-suppliers system_evidence.twpack --qualification-database

Contractual Evidence Requirements

Evidence Specification in Contracts

TRF enables precise specification of evidence requirements:

{
  "contractual_evidence_requirements": {
    "required_artifact_types": [
      "requirement", "design", "test", "component"
    ],
    "domain_extensions": ["automotive", "ai_ml"],
    "coverage_requirements": {
      "requirement_to_test": 0.95,
      "design_to_implementation": 1.0,
      "safety_requirement_to_mechanism": 1.0
    },
    "validation_requirements": {
      "schema_compliance": true,
      "signature_verification": true,
      "completeness_checking": true,
      "cross_reference_validation": true
    },
    "delivery_format": "TWPack v2.0",
    "evidence_timeliness": "within_30_days_of_milestone"
  }
}

Automated Contract Compliance

# Verify contractual evidence requirements
tw contract-check delivered_evidence.twpack --contract requirements.json

# Generate compliance report
tw compliance-report delivered_evidence.twpack --format html --output report.html

# Validate evidence delivery timeline
tw timeline-check delivered_evidence.twpack --milestone-dates milestones.json

Evidence Acceptance Criteria

{
  "acceptance_criteria": {
    "completeness_threshold": 0.95,
    "quality_metrics": {
      "artifact_linkage_coverage": 0.90,
      "test_evidence_completeness": 0.95,
      "design_traceability": 0.98
    },
    "validation_checks": [
      "schema_validation_passed",
      "signature_verification_passed",
      "cross_reference_integrity_confirmed",
      "supplier_qualification_verified"
    ],
    "rejection_criteria": [
      "missing_critical_artifacts",
      "broken_traceability_chains",
      "unqualified_supplier_evidence",
      "expired_certificates_or_signatures"
    ]
  }
}

Multi-Organizational Evidence Integration

Evidence Package Merging

Systematic integration of evidence from multiple sources:

# Merge evidence packages from different suppliers
tw merge base_evidence.twpack supplier1.twpack supplier2.twpack --output integrated.twpack

# Resolve artifact identifier conflicts
tw resolve-conflicts integrated.twpack --strategy namespace_prefix

# Validate merged evidence integrity
tw validate integrated.twpack --check-cross-references

Conflict Resolution

Handling conflicting evidence from different sources:

{
  "conflict_resolution": {
    "identifier_conflicts": {
      "strategy": "namespace_prefix",
      "mapping": {
        "req:FUNC-001": {
          "supplier_a": "sa:req:FUNC-001",
          "supplier_b": "sb:req:FUNC-001"
        }
      }
    },
    "relationship_conflicts": {
      "strategy": "multi_source_tracking",
      "evidence": [
        {
          "link": {"from": "req:FUNC-001", "to": "test:TC-001"},
          "sources": ["supplier_a", "supplier_b"],
          "confidence": 0.95
        }
      ]
    }
  }
}

Gap Analysis Across Tiers

Systematic identification of evidence gaps:

# Identify missing evidence across supply chain tiers
tw gap-analysis --tier0 system_requirements.twpack --tier1 *.twpack --tier2 */evidence.twpack

# Generate gap report with responsibility assignment
tw gap-report --output gaps.html --assign-responsibility

# Track gap resolution progress
tw gap-tracking gaps.json --update-status --output progress.json

Evidence Evolution and Change Management

Version Control Across Organizations

# Track evidence evolution across organizational boundaries
git submodule add https://supplier1.com/evidence.git supplier1_evidence
git submodule add https://supplier2.com/evidence.git supplier2_evidence

# Update to latest supplier evidence
git submodule update --remote

# Create system-level evidence snapshot
tw snapshot system_evidence.twpack --include-submodules

Change Impact Analysis

# Analyze impact of supplier evidence changes
tw change-impact old_evidence.twpack new_evidence.twpack --output impact_report.html

# Identify affected system-level artifacts
tw trace-impact system_evidence.twpack --changed-artifacts supplier_changes.json

# Validate change propagation
tw validate-changes system_evidence.twpack --change-set supplier_changes.json

Continuous Evidence Integration

# Automated evidence integration pipeline
tw ci-pipeline --config evidence_integration.yaml
  # 1. Fetch latest supplier evidence
  # 2. Validate evidence quality and completeness
  # 3. Merge with existing system evidence
  # 4. Run gap analysis and compliance checks
  # 5. Generate updated evidence packages
  # 6. Notify stakeholders of changes

This supply chain-native approach enables scalable evidence management across complex multi-tier development ecosystems while maintaining traceability, quality, and compliance requirements.