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Accessibility¤

Compliance Trestle is committed to making both the project site and its results accessible to persons with disabilities where it is reasonable to do so. This document describes the accessibility measures taken, the guidelines followed, and known limitations.

Project type and scope¤

Compliance Trestle is primarily a command-line application and Python library. Command-line interfaces are generally accessible as-is because they work with any terminal emulator, including those used by screen-reader users (e.g. a Braille terminal, or NVDA with a console window).

The project also publishes a documentation website built with MkDocs Material. The accessibility measures below apply to that site.

Guidelines followed¤

The documentation site targets conformance with Web Content Accessibility Guidelines (WCAG) 2.0 Level AA. The specific criteria addressed are:

WCAG criterion Measure taken
1.1.1 Non-text content — text alternatives for images All informative images in the documentation carry descriptive alt text that conveys the same information as the visual. Decorative images use descriptive context.
1.4.1 Use of colour — colour not used as the only means of conveying information Code blocks use syntax labels and/or contextual prose in addition to colour highlighting.
1.4.3 Contrast (Minimum) — text contrast ≥ 4.5:1 The documentation site ships a light/dark theme toggle (respecting prefers-color-scheme) so users can choose the scheme that provides adequate contrast for them. Both the default (light) and slate (dark) palettes use black primary headings against a white/dark background, meeting the 4.5:1 requirement.
2.1.1 Keyboard — all functionality available from keyboard MkDocs Material's navigation is keyboard-accessible. A "Skip to main content" link is injected as the first focusable element on every page so keyboard-only users can bypass the navigation bar.
2.4.1 Bypass blocks Skip-navigation link provided (see above).
2.4.7 Focus visible A high-contrast focus ring (3 px solid #005eb8) is applied to all interactive elements via docs/css/accessibility.css.
3.1.1 Language of page <html lang="en"> is set via the language: en MkDocs theme option.

Reduced-motion¤

Users who have enabled the operating-system "reduce motion" preference will experience disabled CSS transitions and animations on the documentation site, in line with the prefers-reduced-motion media query.

Screen-reader testing¤

The documentation site has been verified for basic screen-reader compatibility using Orca (GNOME, Linux) against the rendered HTML. The skip-navigation link and ARIA landmark structure provided by MkDocs Material allow Orca users to reach the main content without traversing the full navigation sidebar.

If you encounter a problem reading the documentation with a different screen-reader, please open an issue so it can be investigated.

Command-line interface accessibility¤

The trestle CLI:

  • Outputs plain text to stdout / stderr, which works with any terminal screen-reader or Braille display.
  • Does not rely on colour alone to signal success or failure: every status message carries a textual prefix (INFO, WARNING, ERROR) that is meaningful without colour.
  • Supports --help on all sub-commands, providing a full description of options and arguments in plain text.
  • Does not use cursor-positioning (ncurses-style) TUI elements that can cause screen-reader overdraw.

Known limitations¤

  • The architecture diagram (docs/assets/Canonical_trestle_auditree_workflows.png) is a complex .drawio export. A textual description of that diagram is available in the accompanying docs/architecture.md page.
  • The MkDocs Material version-selector dropdown (provided by the mike plugin) may have limited keyboard accessibility depending on the browser.
  • Third-party badge images served from shields.io embed their text in SVG; screen-readers may not announce them consistently. All badges on the project home page carry alt text that conveys the same information.

Feedback¤

If you discover an accessibility barrier not listed here, please open an issue with the label accessibility. We welcome pull requests that improve accessibility.