Component guidelines

Button (`MdsButton`)

Primary once per region. Secondary for a supporting action. Outline for neutral choices. Ghost for low-emphasis actions. Destructive only for irreversible actions, and confirm them.
Labels are verbs (“Save”, “Delete account”), sentence case, no full stops.
While isLoading is true taps are ignored and a spinner appears. Keep the label so context is not lost.
Small buttons are 36dp tall but keep a 48dp touch target.

Always set mdsLabel. A hint is an example, not a label.
Prefer helper text for rules (“8 characters or more”) and error text for what went wrong and how to fix it.
Errors replace helper text, are announced politely, and show an icon.
The field saves and restores its own state, so several fields can share one screen safely.

Outlined is the default. Use elevated sparingly (one level of lift per screen). Flat groups quiet content.
Make the whole card clickable, not parts of it, and give it a content description if it has no text.

Badge: read-only status. Chip: user choice, toggles. Alert: needs the user’s attention inline.
Tone is semantic: do not use Danger for decoration.

Avatar initials use a stable tone per name; supply name so accessibility gets a description.
Skeletons mirror the final layout’s size to avoid jumps; stop showing them as soon as content arrives.

Use one per screen. It gives every page the same header, spacing and pinned actions.
XML children land in the scrolling content region. Add app:layout_mdsTemplateSlot="footer" to pin a button to the bottom; the footer and its divider stay hidden until there is one.
The primary action goes in the footer so it is always reachable. Keep it to one primary button.
The template does not handle system bar insets. Pad the root in the host Activity (see PageActivity in the sample).