UI, language, and accessibility

Part of the coding standards. docs/architecture.md owns how interface and AI-output language work. docs/testing.md owns the Hungarian parity checks.

Every string is translated

Every user-facing string, including toasts, errors, and accessible names, goes through t(). src/test/i18n-keys.test.ts fails when a literal key is missing from the catalogs or a count call lacks its plural forms. It cannot see dynamic keys (t(`nav.${key}`)) or raw values rendered as text, so check those by hand: an English word in a Hungarian screen is the usual sign (#11, #43).
Store a translation key or error kind in state and translate at render time. English strings stored in state stay English after a reload (#12).
Use the localized feature name everywhere in a catalog: "Interrogatorio", "Keresztkérdezés" (#12, #13 review). The glossary below is the one name per language for each tool, role, and format.
A count goes into the string as count, so i18next picks the plural form: t('libraryPage.sourceCount', { count }), never `${n} ${t('sources')}`. Format numbers and dates with src/lib/date-format.ts, which follows the interface language.
src/test/i18n-untranslated.test.ts fails when a Spanish or Hungarian value is identical to English. When that is intended, such as a product or format name, add it to the test's list under a reason.

Concept	English	Spanish	Hungarian
Crossfire (tool and saved round)	Crossfire	Interrogatorio	Keresztkérdezés
Sparring (tool and saved round)	Sparring	Sparring	Vitapárbaj
Timer	Timer	Cronómetro	Időmérő
Case	Case	Caso	Eset (Vitaeset in titles)
Ruthless (difficulty, intensity)	Ruthless	Despiadado	Kíméletlen
School format	School 4-6-6-3	Formato escolar 4-6-6-3	Iskolai 4-6-6-3
School-format roles (the Timer spells out R1 and R2)	Introductor, R1, R2, Conclusor	Introductor, R1, R2, Conclusor	Bevezető, R1, R2, Záró
Sides in a Sparring turn	Pro, Con	a favor, en contra	Pro, Kontra
Competition formats	Public Forum, Lincoln-Douglas, Policy, British Parliamentary, World Schools, Asian Parliamentary	same as English	same as English
Load (button) / Loading	Load / Loading	Cargar / Cargando	Megnyitás / Betöltés
AI	AI	IA	MI
DebateLab with a suffix			DebateLabba, DebateLabban, DebateLabhoz, DebateLabot (no hyphen, back vowels)

Icon-only links and buttons get an aria-label. The nav label hides below xl, which left the link nameless (#13).
Repeated row actions include the row's name ("Delete <title>"), so screen readers and role queries can tell them apart (#19).
A label for a group of buttons uses role="group" and aria-labelledby (#11).
Lists rendered from model output use index keys, because model strings can repeat (#11).

When shouldReduceMotion is true, render a static element. Passing the flag to the phase but not to initial/animate still animates (#20).

When a store action rejects input (too long, expired, invalid), the UI shows why. A submit button that silently does nothing looks broken (#13).
Clear a composer only after the handler accepts the message, so a rejected draft is not lost (#66 outside diff).
Enforce rules such as deadlines in the store, and add the UI guard as a second layer (#13).

Keep a confirmation dialog open while its request is pending, and close it only on success. Radix closes on click unless you call preventDefault() (#26).
Side effects such as scrolling run on a success signal, not on "loading became false" (#20).
Open a new tab within the click handler. After an awaited request the user activation has expired and popup blockers drop the tab. Show a fallback link (#63).
On phones (below md) the bottom tab bar is the navigation. From md up the header nav is the navigation; there is no menu button at any width, so never show two navs at once (#20).