## Purpose

Define a deterministic Lighthouse quality gate that produces repeatable scores and blocks regressions across required categories.

## Requirements

### Requirement: Deterministic Lighthouse configuration
The project MUST define a deterministic Lighthouse run configuration that specifies:

- a fixed list of URLs to audit
- mobile and desktop runs
- theme variants: `light`, `dark`, and `high-contrast`
- a clean run environment (no browser extensions)
- throttling / device emulation settings

The configuration MUST be checked into the repository.

#### Scenario: Lighthouse config is version-controlled
- **WHEN** a developer checks the repository
- **THEN** a Lighthouse configuration file/script exists and is referenced by a documented command

### Requirement: Lighthouse gate enforces perfect scores
The project MUST provide a command that runs Lighthouse for the configured URLs and variants and fails if any category score is below 100:

- Performance
- Accessibility
- Best Practices
- SEO

The command MUST output the reports as build artifacts (HTML and/or JSON) to a deterministic output directory.

#### Scenario: Gate fails on a regression
- **WHEN** Lighthouse runs and any audited variant scores 99 in any category
- **THEN** the command exits non-zero and reports which URL/variant failed

#### Scenario: Gate produces artifacts
- **WHEN** Lighthouse runs successfully
- **THEN** the reports are written to the configured output directory for later inspection

### Requirement: Repeatable scoring rule
The Lighthouse gate MUST define a repeatable scoring rule to reduce run-to-run noise.

At minimum, it MUST document one of the following:

- single-run with fixed throttling and clean environment, or
- multiple runs per variant with a deterministic selection rule (e.g., median)

#### Scenario: Run-to-run method is documented
- **WHEN** a developer runs the gate locally or in CI
- **THEN** the method for selecting/reporting scores is explicitly documented