ui8px

ui8px validates utility class maps against an 8 + 4 spacing policy.

Run directly:

npx ui8px@latest --design grid --input ui8kit.map.json --output ui8kit.map.backlog.json

You can also run with npm or bun:

npm exec ui8px@latest -- --design grid --input ui8kit.map.json --output ui8kit.map.backlog.json
bunx ui8px@latest --design grid --input ui8kit.map.json --output ui8kit.map.backlog.json

Usage

npx ui8px@latest --design grid --input <input-json> --output <backlog-json> [options]

Options

• --input <path> — input class map JSON (required)
• --output <path> — output backlog JSON path (required)
• --spacing-base <number> — multiplier for var(--spacing); default 4
• --root-font-size <number> — root font size for rem; default 16
• --verbose — print each violation in terminal
• --design grid — required mode flag
• -h, --help — print usage and exit with 0

Output examples

Validation failed (without --verbose)

npx ui8px@latest --design grid --input ui8kit.map.json --output ui8kit.map.backlog.json

Input: ui8kit.map.json
Output: ui8kit.map.backlog.json
Design: grid
Spacing base: 4px
Checked classes: 120
Checked declarations: 340
Violations: 2
Found 2 violations.
Report saved to: /Users/.../ui8kit.map.backlog.json

Validation failed (with --verbose)

npx ui8px@latest --design grid --input ui8kit.map.json --output ui8kit.map.backlog.json --verbose

Input: ui8kit.map.json
Output: ui8kit.map.backlog.json
Design: grid
Spacing base: 4px
Checked classes: 120
Checked declarations: 340
Violations: 2
Found 2 violations.
- h-11 | height: calc(var(--spacing) * 11) -> 44px
- ml-7 | margin-left: 7px -> 7px
Report saved to: /Users/.../ui8kit.map.backlog.json

No violations

npx ui8px@latest --design grid --input ui8kit.clean.map.json --output ui8kit.clean.backlog.json

Input: ui8kit.clean.map.json
Output: ui8kit.clean.backlog.json
Design: grid
Spacing base: 4px
Checked classes: 56
Checked declarations: 110
Violations: 0
No violations found.
Report saved to: /Users/.../ui8kit.clean.backlog.json

Parser errors

Error: --input is required.

Error: --output is required.

Error: Unknown option: --foo

Exit codes

• 0 — no violations
• 1 — violations found
• 2 — invalid usage or runtime error

ui8px

ui8px validates utility class maps against an 8 + 4 spacing policy.

No one-off install is required:

npx ui8px@latest --design grid --input ui8kit.map.json --output ui8kit.map.backlog.json

You can also run with npm or bun:

npm exec ui8px@latest -- --design grid --input ui8kit.map.json --output ui8kit.map.backlog.json
bunx ui8px@latest --design grid --input ui8kit.map.json --output ui8kit.map.backlog.json

Usage

npx ui8px@latest --design grid --input <input-json> --output <backlog-json> [options]

Example

npx ui8px@latest --design grid --input ui8kit.map.json --output ui8kit.map.backlog.json --verbose

Terminal output:

Input: ui8kit.map.json
Output: ui8kit.map.backlog.json
Design: grid
Spacing base: 4px
Checked classes: 120
Checked declarations: 340
Violations: 2
Found 2 violations.
- h-11 | height: calc(var(--spacing) * 11) -> 44px
- ml-7 | margin-left: 7px -> 7px
Report saved to: /Users/.../ui8kit.map.backlog.json

Example backlog file:

{
  "meta": {
    "input": "ui8kit.map.json",
    "output": "ui8kit.map.backlog.json",
    "design": "grid",
    "spacingBase": 4,
    "rootFontSize": 16,
    "generatedAt": "2026-03-11T12:00:00.000Z",
    "classesScanned": 120,
    "declarationsScanned": 340
  },
  "summary": {
    "classesChecked": 120,
    "declarationsChecked": 340,
    "violations": 2
  },
  "violations": [
    {
      "className": "h-11",
      "property": "height",
      "rawValue": "calc(var(--spacing) * 11)",
      "resolvedPx": 44,
      "reason": "44px is not aligned to the 8/4px layout policy"
    },
    {
      "className": "ml-7",
      "property": "margin-left",
      "rawValue": "7px",
      "resolvedPx": 7,
      "reason": "7px is not aligned to the 8/4px layout policy"
    }
  ]
}

--help

npx ui8px@latest --help
npx ui8px@latest -h

Shows usage instructions and exits with code 0.

Example usage output

Usage:
  npx ui8px --design grid --input <path> --output <path> [options]

Options:
  --design grid          validate mode (required for spacing checks)
  --input <path>         path to class map JSON
  --output <path>        backlog output path
  --spacing-base <number>    spacing base for var(--spacing) (default: 4)
  --root-font-size <number>  root font size for rem conversion (default: 16)
  --verbose                  show detailed violations in console
  -h, --help                show help

Parameters

• --design grid — required and only supported mode.
• --input <path> — input class map JSON (required).
• --output <path> — output backlog JSON path (required).
• --spacing-base <number> — multiplier for var(--spacing) (default 4).
• --root-font-size <number> — base font size for rem values (default 16).
• --verbose — print detailed violations.
• -h, --help — show usage.

Argument parsing behaviour

• --design must be exactly grid.
• One of the required flags --input and --output can be omitted only with --help.
• Unknown flags and extra positional arguments are rejected.
• Missing required values (--input, --output, --spacing-base, --root-font-size, --design) result in a validation error.
• --verbose is optional and defaults to false.

Examples of parser errors

npx ui8px@latest --design grid --output ui8kit.map.backlog.json

Error: --input is required.
Exit code: 2

npx ui8px@latest --design grid --input ui8kit.map.json

Error: --output is required.
Exit code: 2

npx ui8px@latest --design grid --input ui8kit.map.json --output ui8kit.map.backlog.json --foo

Error: Unknown option: --foo
Exit code: 2

Error messages are prefixed with Error: by the parser and printed by the CLI wrapper before exiting.

Example with no violations

npx ui8px@latest --design grid --input ui8kit.clean.map.json --output ui8kit.clean.backlog.json

Terminal output:

Input: ui8kit.clean.map.json
Output: ui8kit.clean.backlog.json
Design: grid
Spacing base: 4px
Checked classes: 56
Checked declarations: 110
Violations: 0
No violations found.
Report saved to: /Users/.../ui8kit.clean.backlog.json

Example backlog:

{
  "meta": {
    "input": "ui8kit.clean.map.json",
    "output": "ui8kit.clean.backlog.json",
    "design": "grid",
    "spacingBase": 4,
    "rootFontSize": 16,
    "generatedAt": "2026-03-11T12:10:00.000Z",
    "classesScanned": 56,
    "declarationsScanned": 110
  },
  "summary": {
    "classesChecked": 56,
    "declarationsChecked": 110,
    "violations": 0
  },
  "violations": []
}

--verbose vs standard output

npx ui8px@latest --design grid --input ui8kit.map.json --output ui8kit.map.backlog.json

Standard output:

Input: ui8kit.map.json
Output: ui8kit.map.backlog.json
Design: grid
Spacing base: 4px
Checked classes: 120
Checked declarations: 340
Violations: 2
Found 2 violations.
Report saved to: /Users/.../ui8kit.map.backlog.json

npx ui8px@latest --design grid --input ui8kit.map.json --output ui8kit.map.backlog.json --verbose

Verbose output:

Input: ui8kit.map.json
Output: ui8kit.map.backlog.json
Design: grid
Spacing base: 4px
Checked classes: 120
Checked declarations: 340
Violations: 2
Found 2 violations.
- h-11 | height: calc(var(--spacing) * 11) -> 44px
- ml-7 | margin-left: 7px -> 7px
Report saved to: /Users/.../ui8kit.map.backlog.json

Exit codes

• 0 — no violations.
• 1 — violations found.
• 2 — invalid usage or runtime error.