Make the Instruction agent reply in the user's language, at a human pace

The agent answers in the language each message is written in (Indonesian
or English), whatever the UI language; short replies such as "LLM" keep
the conversation's language. inLang() runs t() in that language.

Each turn now reads like a person: a thinking step with what the agent is
doing, the reply typed out with "Thought for Ns" above it, a short typing
pause, then one question, with its options shown once it is typed.
Reduced motion skips the animation.

"dari file LLM" / "from the document X" is read as the topic, and topics
keep the user's capitals.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

src/i18n.ts

@@ -269,6 +269,11 @@ const en = {
   'ins.budgetVideo': '{n} per video',
   'agent.name': 'Express Agent',
   'agent.status': 'Asks when something is unclear',
+  'agent.statusThinking': 'Thinking…',
+  'agent.think1': 'Reading your message',
+  'agent.think2': 'Checking the plan',
+  'agent.think3': 'Working out what is still unclear',
+  'agent.thought': 'Thought for {s}s',
   'agent.greeting': 'Hi! Tell me what to create from the Brain and how often, or what to research on the internet. If anything is unclear, I will ask you here.',
   'agent.understood': 'Got it. Here is the plan so far:\n{list}',
   'agent.added': 'Added to the plan:\n{list}',
@@ -638,6 +643,11 @@ const id: Record<Key, string> = {
   'ins.budgetVideo': '{n} per video',
   'agent.name': 'Agen Express',
   'agent.status': 'Bertanya bila ada yang belum jelas',
+  'agent.statusThinking': 'Sedang berpikir…',
+  'agent.think1': 'Membaca pesan Anda',
+  'agent.think2': 'Memeriksa rencana',
+  'agent.think3': 'Mencari yang masih belum jelas',
+  'agent.thought': 'Berpikir {s} detik',
   'agent.greeting': 'Halo! Ceritakan konten apa yang perlu dibuat dari Otak dan seberapa sering, atau apa yang perlu diriset di internet. Kalau ada yang belum jelas, saya tanyakan di sini.',
   'agent.understood': 'Siap. Ini rencananya sejauh ini:\n{list}',
   'agent.added': 'Ditambahkan ke rencana:\n{list}',
@@ -760,6 +770,8 @@ function initial(): Lang {
 }
 
 let lang: Lang = initial()
+// The language of the text being built right now, when it differs from the UI (see inLang).
+let override: Lang | null = null
 const listeners = new Set<() => void>()
 if (typeof document !== 'undefined') document.documentElement.lang = lang
 
@@ -774,10 +786,17 @@ export function setLang(next: Lang) {
 }
 
 export function t(key: Key, vars?: Record<string, string | number>): string {
-  const text = dictionaries[lang][key] ?? en[key]
+  const text = dictionaries[override ?? lang][key] ?? en[key]
   return vars ? text.replace(/\{(\w+)\}/g, (m, k) => (k in vars ? String(vars[k]) : m)) : text
 }
 
+/** Runs fn with t() in another language, e.g. the agent answering in the language the user writes in. */
+export function inLang<T>(l: Lang, fn: () => T): T {
+  const previous = override
+  override = l
+  try { return fn() } finally { override = previous }
+}
+
 /** Re-renders the component when the language changes; returns the active language. */
 export function useLang(): Lang {
   return useSyncExternalStore(cb => { listeners.add(cb); return () => listeners.delete(cb) }, getLang)