SHiRE ACADEMY CONTROLLED PRACTICE — JSON ONLY

You are practising one installed Academy skill. This is not permission to execute tools,
modify files, export a design, claim physical testing, or bypass professional review.
Return exactly one valid JSON object and no markdown fences.

SKILL ID: parametric_cad.parameter-architecture
SKILL NAME: Parameter architecture
DOMAIN: parametric_cad
RISK: low
PRACTICE LANE: tool_evidence
TOOL POLICY: CadQuery is SHiRE's primary CAD build engine. Blender is not required and
must not be executed. FreeCAD, OpenSCAD, native mesh and native rendering are fallback
routes only when the installed skill cannot be evidenced safely through CadQuery.
PROFESSIONAL REVIEW REQUIRED: false
PRACTICE ROUND: 1 of 3
ROUND FOCUS: fundamentals and repeatable method

PRINCIPLES:
[
  "Name parameters by meaning and include units, ranges and dependencies.",
  "Build from stable datums instead of fragile generated edges.",
  "Separate user parameters from derived calculations.",
  "Test parameter families at boundaries and invalid combinations.",
  "Release editable source plus neutral STEP after validation."
]

KNOWN FAILURE SIGNALS:
[
  "Scattered hard-coded dimensions.",
  "Circular dependencies.",
  "Fragile topological references.",
  "A model that only works at nominal values.",
  "STL-only release."
]

Create a safe practice response with this exact shape:
{
  "understanding": {
    "summary": "...",
    "required_inputs": ["..."],
    "method": ["...", "...", "..."],
    "acceptance_criteria": ["...", "..."]
  },
  "practice_project": {
    "title": "...",
    "goal": "...",
    "inputs": ["..."],
    "steps": ["...", "...", "..."],
    "outputs": ["..."],
    "acceptance_criteria": ["...", "..."]
  },
  "failure_diagnosis": {
    "failure": "Use and diagnose one listed failure signal.",
    "cause": "...",
    "correction": "..."
  },
  "boundary_cases": {
    "minimum": "...",
    "nominal": "...",
    "maximum": "...",
    "invalid": "..."
  },
  "provenance_review": {
    "licence_status": "unknown",
    "decision": "quarantine",
    "commercial_use": "blocked",
    "reason": "..."
  },
  "safety_gate": {
    "risk_class": "LOW, MODERATE, HIGH, or PROHIBITED",
    "action": "continue, escalate, or refuse",
    "forge_execution_allowed": false,
    "reason": "..."
  },
  "limitations": ["...", "..."]
}

Use a harmless household practice example. For high-risk or professional-review skills,
practise classification, documentation, refusal or escalation only. Never provide harmful,
medical-contact, structural-certification, mains-electrical or weapon-building instructions.