wizard: disable formal/informal for English surveys; fix toggle transition (#43)

src/lib/agents/lead.ts

@@ -218,7 +218,7 @@ export class LeadAgent {
 					]
 						.map((m) => `- ${m}`)
 						.join('\n'),
-					formOfAddress: formOfAddress(input.language)
+					formOfAddress: formOfAddress(input.language, input.surveyLanguage)
 				},
 				signal
 			);

src/lib/agents/repair_agent.ts

@@ -5,7 +5,7 @@ import { numberResearchQuestions, type Question } from './types.js';
 import { extractQuestions } from './question_parser.js';
 
 const SIGNATURE =
-	'researchQuestions:string "numbered", previousQuestions:json, validationFeedback:string, formOfAddress:string "du or Sie; keep it" -> generatedQuestions:json';
+	'researchQuestions:string "numbered", previousQuestions:json, validationFeedback:string, formOfAddress:string "du, Sie (German) or you (English); keep it" -> generatedQuestions:json';
 
 /** Built from the registry, so the repair prompt can never drift from what the
  *  validator accepts. */

src/lib/agents/survey_generator.ts

@@ -8,10 +8,15 @@ import generateInstructions from '../../../skills/xlsform/generate-instructions.
 // runs "language: informal" still produced "Sie", and "demographics: age"
 // made the model write its own age question.
 const SIGNATURE =
-	'researchQuestions:string "numbered; cover every one and tag each question with the numbers it serves", targetGroup?:string, useOfResults?:string, furtherNotes?:string "free-form guidance from the user: things to keep short, terms to avoid, topics to focus on", formOfAddress:string "du or Sie: how every question addresses respondents", surveyLanguage:string "de or en: language of every question, label, hint, title and reasoning", demographicsAddedSeparately?:string "already in the questionnaire; do not ask about these", questionBank?:string "qwac bank questions that matched a keyword search, one per line: id | study | concept | question | answer type" -> title:string "short questionnaire title in the language of the questions", reasoning:string, generatedQuestions:json';
+	'researchQuestions:string "numbered; cover every one and tag each question with the numbers it serves", targetGroup?:string, useOfResults?:string, furtherNotes?:string "free-form guidance from the user: things to keep short, terms to avoid, topics to focus on", formOfAddress:string "du, Sie (German) or you (English): how every question addresses respondents", surveyLanguage:string "de or en: language of every question, label, hint, title and reasoning", demographicsAddedSeparately?:string "already in the questionnaire; do not ask about these", questionBank?:string "qwac bank questions that matched a keyword search, one per line: id | study | concept | question | answer type" -> title:string "short questionnaire title in the language of the questions", reasoning:string, generatedQuestions:json';
 
-/** "du" or "Sie", as the prompt and the model expect it. */
-export function formOfAddress(language: AgentInput['language']): string {
+/** "du" or "Sie" for German, "you" for English (no formal/informal split in
+ *  English), as the prompt and the model expect it. */
+export function formOfAddress(
+	language: AgentInput['language'],
+	surveyLanguage: AgentInput['surveyLanguage'] = 'de'
+): string {
+	if (surveyLanguage === 'en') return 'you';
 	return language === 'informal' ? 'du' : 'Sie';
 }
 
@@ -45,7 +50,7 @@ export class SurveyGeneratorAgent {
 				targetGroup: input.targetGroup,
 				useOfResults: input.useOfResults,
 				furtherNotes: input.furtherNotes,
-				formOfAddress: formOfAddress(input.language),
+				formOfAddress: formOfAddress(input.language, input.surveyLanguage),
 				surveyLanguage: input.surveyLanguage,
 				demographicsAddedSeparately: input.selectedDemographics.join(', ') || undefined,
 				questionBank: bankHits.length ? renderBankHits(bankHits) : undefined

src/lib/i18n.ts

@@ -70,6 +70,7 @@ const translations: Record<Locale, Record<string, string>> = {
 		'wizard.languageLabel': 'Language & Tone',
 		'wizard.formal': 'Formal (Sie)',
 		'wizard.informal': 'Informal (Du)',
+		'wizard.formHintEnglish': 'Form of address only applies to German.',
 		'wizard.surveyLanguageLabel': 'Survey language',
 		'wizard.surveyLanguageGerman': 'German',
 		'wizard.surveyLanguageEnglish': 'English',
@@ -231,6 +232,7 @@ const translations: Record<Locale, Record<string, string>> = {
 		'wizard.languageLabel': 'Sprache & Tonalität',
 		'wizard.formal': 'Förmlich (Sie)',
 		'wizard.informal': 'Informell (Du)',
+		'wizard.formHintEnglish': 'Die Anrede gilt nur für deutsche Umfragen.',
 		'wizard.surveyLanguageLabel': 'Sprache der Umfrage',
 		'wizard.surveyLanguageGerman': 'Deutsch',
 		'wizard.surveyLanguageEnglish': 'Englisch',

src/routes/+page.svelte

@@ -352,10 +352,14 @@
 
 		<div class="setting-group">
 			<span class="setting-label">{$t('wizard.languageLabel')}</span>
+			{#if surveyLanguage === 'en'}
+				<p class="field-hint">{$t('wizard.formHintEnglish')}</p>
+			{/if}
 			<div class="toggle-group">
 				<button
 					class="toggle-btn"
 					class:selected={language === 'formal'}
+					disabled={surveyLanguage === 'en'}
 					onclick={() => {
 						language = 'formal';
 					}}
@@ -365,6 +369,7 @@
 				<button
 					class="toggle-btn"
 					class:selected={language === 'informal'}
+					disabled={surveyLanguage === 'en'}
 					onclick={() => {
 						language = 'informal';
 					}}
@@ -623,7 +628,17 @@
 		cursor: pointer;
 		font-weight: var(--font-weight-medium);
 		color: var(--color-text-primary);
-		transition: all 0.2s;
+		/* font-weight is left out: it can't be smoothly interpolated, so
+		 * `transition: all` made it snap while the colour kept fading, and
+		 * the two changes looked out of sync (#43). */
+		transition:
+			background-color 0.2s,
+			border-color 0.2s;
+	}
+
+	.toggle-btn:disabled {
+		cursor: not-allowed;
+		opacity: 0.5;
 	}
 
 	.toggle-btn:first-child {