Source: https://guthlabs.ai/docs/instruments/metronome-panel/implementation/

instrument implementation / implementation-contract

# Metronome Panel implementation

A source-bound implementation contract for Metronome Panel; deployment and executable qualification remain separate.

Status: **VERIFIED_CLEAN**Lifecycle: **implementation-contract**

## 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**: t6-033

**Effect**: Computation or source lookup only

## Input and validation requirements

BPM = 0 produces an undefined click interval unless the input is explicitly rejected. A separate convention ambiguity can also produce 250 ms versus 1000 ms for the same displayed settings if subdivision is interpreted per beat versus per bar.

## 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": {
    "BPM": 120,
    "time_signature": "4/4",
    "subdivision": 1,
    "accent_pattern": [
      1,
      0,
      0,
      0
    ],
    "accent_pattern_scope": "one bar, one entry per click",
    "bar_count": 1
  },
  "expected_outputs": {
    "click_interval_ms": 500,
    "click_times_ms": [
      0,
      500,
      1000,
      1500
    ],
    "accented_click_indices": [
      0
    ]
  },
  "working": "BPM = 120 beats/minute. One subdivision gives 1 click/beat. Interval = 60000 / 120 / 1 = 500 ms. A 4/4 bar has 4 beats, so click times are 0, 0+500 = 500, 500+500 = 1000, and 1000+500 = 1500 ms. The accent pattern [1,0,0,0] accents only index 0."
}
````

## Other records

[01**Overview**](<https://guthlabs.ai/docs/instruments/metronome-panel/>)[02**Mechanism**](<https://guthlabs.ai/docs/instruments/metronome-panel/mechanism/>)[04**Qualification**](<https://guthlabs.ai/docs/instruments/metronome-panel/qualification/>)

## Sources and evidence

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

- `VERIFIED_LEDGER.json`

- `evidence-tranche6/tranche6-results.json`