Masked input

Keyboard

• Native <input>: typing edits the value in place, Tab moves focus in and out; disabled removes it from the tab order (same as input). There is no keyboard shortcut and nothing to escape out of — the component renders no popover or calendar.
• Backspace over an auto-inserted separator deletes the digit before it too (maskInput), so deleting never gets stuck on a character the user did not type — same behaviour as masked-date-input, covered by field-masks.test.ts.
• No arrow-key segment navigation; the caret moves through the mask like an ordinary text field, only separator characters are special-cased by the template.
• inputMode is set per mask (numeric for IČO/PSČ/rodné číslo, text for DIČ), so mobile keyboards match the expected characters.

ARIA

• Accessible name: pass ariaLabel, rendered as a native aria-label on the <input> — the same limitation as input applies when the component is used inside <Field>/<DrawerField>, whose <label> is not linked to its control via htmlFor/id (see text-field/input.a11y.md). MaskedInput does not add that link either; callers must supply ariaLabel themselves, and every current call site does.
• aria-invalid is set only when invalid is true (aria-invalid={invalid || undefined}): a valid or empty field carries no aria-invalid attribute at all rather than "false" — same convention as masked-date-input.
• Error linking, unlike masked-date-input (which has no describedBy prop at all): MaskedInput accepts describedBy and wires it to aria-describedby on the input (aria-describedby={describedBy ?? fieldDescribedBy}).
• The formless caller (NewContactDialog, rodné číslo) passes describedBy={rcErrId} and gives the rendered <span class="fl-err"> that same id — explicitly linked, as before.
• The field callers (FirmyPage, IČO/DIČ/PSČ inside <DrawerField>) still do not pass describedBy explicitly, but as of acrm MR !4085 (28 Sep 2026, "fix(ui): chyba pod DS Field se čtečce provází sama") they no longer need to: MaskedInput reads useFieldDescribedBy() and falls back to it, and <Field>/<DrawerField> now give the rendered error (or hint) span an automatic id and pass it down through that context. A screen reader user is now told both that the field is invalid (aria-invalid) and why (the linked error text), with no per-call-site wiring — see text-field/field.a11y.md's ARIA section for the mechanism.
• The ghost span (.acrm-mask-ghost / .fl-mask-ghost) is aria-hidden="true" in both variants — it visually echoes the typed value plus the remaining template; exposing it would read the value twice.

Focus

• field variant: focus is drawn by the surrounding .acrm-inputwrap (:focus-within), same ring as input — border-color: var(--accent) + 3px ring at 16% --accent. .is-error keeps the same geometry with --critical; a focused error field shows the accent ring (focus rule wins by source order, same as input).
• formless variant: the input itself has no border (.fl-mask-in is transparent and absolutely positioned over the ghost), so it relies on the row's own focus treatment (.fl-row:has(.fl-mask-in:focus) tints the row) rather than drawing a dedicated ring — same as masked-date-input.

Contrast

Computed from packages/ui/src/tokens/tokens.css (WCAG 2.x relative luminance) — the same token set already measured in text-field/input.a11y.md and masked-date-input.a11y.md:

• Typed value (valid) --fg on --surface-100 — 17.59:1 light / 13.09:1 dark (field variant, --surface-50 in dark); 17.59:1 light / 14.53:1 dark (formless variant, dialog body surface).
• Typed value (invalid) --critical-ink — 5.37:1 / 5.80:1, passes AA in both variants (same token as masked-date-input's invalid state).
• Ghost .rest --fg-muted — 2.85:1 light / 3.27–3.63:1 dark, below AA 4.5:1 for text; it is a template echo, not content, same system-wide --fg-muted limit as every other muted placeholder/ghost in this family.
• Focus border --accent — 4.44:1 light / 3.83:1 dark, passes the 3:1 non-text minimum.
• Error border --critical (field variant only) — 3.91:1 light / 4.35:1 dark, passes 3:1.
• Resting hairline --border-strong (field variant only) — 1.38:1 light / 1.55:1 dark, hairline, below the 3:1 non-text minimum — same as every .acrm-inputwrap at rest.

Known limits

• ~~describedBy/aria-describedby linking depends on the caller wiring it — one call site does (NewContactDialog), the drawer call sites do not (FirmyPage).~~ Fixed in acrm MR !4085 (28 Sep 2026) via useFieldDescribedBy(): every call site now gets aria-describedby for free from the enclosing <Field>/<DrawerField> unless it passes its own describedBy — see ARIA above.
• <Field>/<DrawerField> do not link label and control — same gap as input; the accessible name must be supplied by the screen via ariaLabel.
• No live region and no "character rejected" feedback: a dropped keystroke (a letter typed into a numeric-only slot) simply does not appear, with nothing announced to a screen reader user — same limit as masked-date-input.
• The ghost's ARIA-hidden echo means the visual template ("________" for an empty IČO) is not itself announced; a screen reader user only hears the label and, once typed, the value — intended, but worth knowing if a future caller wants the template read aloud.