Beat/Measure Duration & Song Length Estimator 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

t4-145

Effect

Computation or source lookup only

Input and validation requirements

BPM = 0 makes the duration formula undefined because it divides by zero; the instrument must reject that input. The 6/8 probe also exposes a convention hazard because treating the numerator as beatsPerBar differs from conventional compound-meter grouping.

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": {
    "mode": "duration",
    "BPM": 120,
    "time_signature": "4/4",
    "beatsPerBar": 4,
    "bar_count": 16
  },
  "expected_outputs": {
    "duration_seconds": 32,
    "duration_minutes": 0.5333333333
  },
  "working": "Beat duration = 60/120 = 0.5 seconds. Beats in song = 16 × 4 = 64 beats. Duration = 64 × 0.5 = 32 seconds. Minutes = 32/60 = 0.5333333333 minutes."
}

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-tranche4/tranche4-results.json