Break-Even & Contribution Margin Dashboard implementation

Binding contract

This record describes what an executable surface must bind and validate. It does not claim that a public calculator, package, or production route is deployed.

Record owner

Guth Instruments

Lifecycle

verified-clean

Evidence ID

t5-103

Effect

Computation or source lookup only

Input and validation requirements

The specification permits inputs that produce undefined division, especially price = 0 and CM = 0, without stating validation behavior. It also does not define handling for nonpositive contribution margins, which can yield negative unit requirements for a positive target profit, or clarify whether target profit is signed.

Required corrections

No binding erratum is attached to this unique-name record. Implementers must still preserve the declared units, domain, and failure behavior.

Inspectable interface fixture

The sample below is evidence for interface and validation tests, not a production implementation.

{
  "inputs": {
    "price": 50,
    "variable_cost": 30,
    "fixed_costs": 10000,
    "target_profit": 5000,
    "currency": "USD",
    "unit_basis": "USD per unit"
  },
  "expected_outputs": {
    "CM": 20,
    "CM_ratio": 0.4,
    "units_for_target_profit": 750
  },
  "working": "CM = 50 − 30 = 20 USD/unit. CM ratio = 20 / 50 = 0.4 = 40%. Required contribution = 10,000 + 5,000 = 15,000 USD. Target-profit units = 15,000 / 20 = 750 units."
}

Other records

Sources and evidence

These pointers bind the page to evidence. They do not grant authority or collapse verification into deployment.

• VERIFIED_LEDGER.json
• evidence-tranche5/tranche5-results.json