docs/adr/018-glitchtip-frontend-error-tracking.md

@@ -0,0 +1,86 @@
+# ADR-018: GlitchTip frontend error tracking via @sentry/sveltekit
+
+**Date:** 2026-05-17  
+**Status:** Accepted  
+**Deciders:** Marcel Raddatz
+
+---
+
+## Context
+
+The Familienarchiv had no client-side error reporting. When a user encountered a crash
+or unhandled error in the SvelteKit frontend, there was no way for the operator to
+observe it — errors were invisible until a user manually reported them. A GlitchTip
+instance (self-hosted, Sentry-compatible) was already running as part of the
+observability stack (`docker-compose.observability.yml`). The backend already reported
+server-side errors to it.
+
+We needed a way to:
+1. Capture frontend errors automatically and route them to GlitchTip.
+2. Give users a visible error identifier they can include in a support message.
+3. Do this without leaking personally identifiable information (PII) from the family
+   archive — documents contain personal histories, names, and relationships.
+
+---
+
+## Decision
+
+Use `@sentry/sveltekit` (the official Sentry SDK for SvelteKit) to:
+
+- Initialise with `sendDefaultPii: false` on both `hooks.server.ts` and `hooks.client.ts`.
+- Pass a callback to `Sentry.handleErrorWithSentry()` that returns
+  `{ message, errorId }` where `errorId` is `Sentry.lastEventId()` when Sentry
+  captured the event, or a fresh `crypto.randomUUID()` as fallback.
+- Display the `errorId` on the `+error.svelte` page so users can include it in a
+  report to the operator.
+
+The SDK is initialised with `enabled: !!import.meta.env.VITE_SENTRY_DSN` so that
+development and CI builds without a DSN configured do not send any events.
+
+`VITE_SENTRY_DSN` is a write-only ingest key — it can POST events to GlitchTip but
+cannot read them. It is safe to include in the client bundle per the Sentry security
+model; it does not require rotation like a password.
+
+---
+
+## Alternatives considered
+
+**Sentry SaaS** — rejected. The archive contains private family documents and personal
+history. Sending error events with stack traces to a US-hosted third party is
+inconsistent with the project's data-minimisation posture. Self-hosted GlitchTip on
+the same Hetzner VPS keeps all data on infrastructure the operator controls.
+
+**Custom error logging endpoint** — rejected. The @sentry/sveltekit SDK handles
+SvelteKit's hook lifecycle, source-map upload, and event grouping automatically.
+Reimplementing this would cost significant engineering time for no benefit.
+
+**Log-only (no user-visible errorId)** — rejected. Without a visible error ID, users
+can only describe what happened in natural language, making it hard to correlate a
+report with a specific GlitchTip event. The `errorId` closes this gap at negligible UI
+cost.
+
+---
+
+## Consequences
+
+**Positive:**
+- Frontend errors are now observable without requiring user reports.
+- Users can provide an `errorId` that maps directly to a GlitchTip event.
+- `sendDefaultPii: false` ensures names, IPs, and cookie values are not included in
+  captured events.
+- `tracesSampleRate: 0.1` limits trace volume to 10% of transactions, keeping
+  GlitchTip load low on the shared VPS.
+
+**Negative / trade-offs:**
+- The `@sentry/sveltekit` SDK is now a production dependency. SDK updates must be
+  reviewed for changes to the default PII scrubbing behaviour.
+- The `handleError` callback in both hooks returns a hardcoded English message
+  (`'An unexpected error occurred'`). This bypasses Paraglide i18n — the error page
+  will always show English text when the hooks are active, regardless of the user's
+  locale. This is acceptable because: (a) the error page is a last-resort fallback
+  not part of normal UX, (b) the `errorId` is the actionable information, not the
+  message text. A future ADR may address this if internationalised error messages
+  become a requirement.
+- `Sentry.lastEventId()` returns `undefined` when Sentry did not capture the event
+  (e.g. DSN not configured). The `crypto.randomUUID()` fallback guarantees an `errorId`
+  is always present, but that UUID will not appear in GlitchTip.

docs/architecture/c4/l1-context.puml

@@ -8,9 +8,11 @@ Person(member, "Family Member", "Access by administrator invite. Searches, brows
 
 System(familienarchiv, "Familienarchiv", "Web application for digitising, organising, and searching family documents")
 System_Ext(mail, "Email Service", "SMTP server. Delivers notification emails (mentions, replies) and password-reset links.")
+System_Ext(glitchtip, "GlitchTip", "Self-hosted error tracking (Sentry-compatible). Receives frontend and backend error events with stack traces.")
 
 Rel(admin, familienarchiv, "Manages via browser", "HTTPS")
 Rel(member, familienarchiv, "Searches, reads, and transcribes via browser", "HTTPS")
 Rel(familienarchiv, mail, "Sends notification and password-reset emails (optional)", "SMTP")
+Rel(familienarchiv, glitchtip, "Sends error events with errorId and stack trace", "HTTPS")
 
 @enduml

frontend/eslint.config.js

@@ -38,7 +38,10 @@ export default defineConfig(
 			'no-undef': 'off',
 			// This rule is designed for Svelte 5's own routing system using resolve().
 			// In SvelteKit, <a href> and goto() from $app/navigation are the correct patterns — resolve() is not needed.
-			'svelte/no-navigation-without-resolve': 'off'
+			'svelte/no-navigation-without-resolve': 'off',
+			// Prevents accidental console.log left in source. console.warn and console.error
+			// are still permitted for intentional server-side logging (e.g. hooks.server.ts).
+			'no-console': ['error', { allow: ['warn', 'error'] }]
 		}
 	},
 	{
@@ -71,6 +74,13 @@ export default defineConfig(
 			]
 		}
 	},
+	{
+		// E2E tests use console.log for diagnostic output — allow it there.
+		files: ['e2e/**'],
+		rules: {
+			'no-console': 'off'
+		}
+	},
 	{
 		files: ['**/*.spec.ts', '**/*.test.ts'],
 		rules: {

frontend/messages/de.json

@@ -473,7 +473,7 @@
 	"dashboard_reader_stats_persons_short": "Pers.",
 	"dashboard_reader_stats_stories_short": "Gesch.",
 	"dashboard_reader_draft_meta": "Entwurf · zuletzt bearbeitet {relative}",
-	"dashboard_resume_label": "Zuletzt geöffnet:",
+	"dashboard_resume_label": "Weiter, wo du aufgehört hast",
 	"dashboard_resume_fallback": "Unbekanntes Dokument",
 	"doc_status_placeholder": "Platzhalter",
 	"doc_status_uploaded": "Hochgeladen",
@@ -773,19 +773,15 @@
 	"admin_invite_created_title": "Einladung erstellt",
 	"admin_invite_created_desc": "Teile diesen Link mit der einzuladenden Person:",
 	"admin_invite_revoke_confirm": "Einladung wirklich widerrufen?",
-
 	"greeting_morning": "Guten Morgen, {name}.",
 	"greeting_day": "Hallo, {name}.",
 	"greeting_evening": "Guten Abend, {name}.",
-
-	"dashboard_resume_label": "Weiter, wo du aufgehört hast",
 	"dashboard_blocks": "{count} Abschnitte",
 	"dashboard_resume_cta": "Weitertranskribieren",
 	"dashboard_resume_other": "oder anderen Brief wählen",
 	"dashboard_empty_title": "Noch kein Dokument begonnen",
 	"dashboard_empty_body": "Wähle ein Dokument aus dem Archiv, um mit der Transkription zu beginnen.",
 	"dashboard_empty_cta": "Zum Archiv",
-
 	"dashboard_mission_caption": "Offene Aufgaben",
 	"queue_segment": "Segmentieren",
 	"queue_segment_blurb": "Seiten aufteilen",
@@ -795,7 +791,6 @@
 	"queue_review_blurb": "Texte kontrollieren",
 	"queue_n_open": "{n} offen",
 	"queue_show_all": "Alle anzeigen →",
-
 	"pulse_eyebrow": "Diese Woche",
 	"pulse_headline": "Ihr habt {pages} Seiten bearbeitet.",
 	"pulse_you": "Du selbst hast {pages} davon bearbeitet.",
@@ -803,19 +798,15 @@
 	"pulse_transcribed": "Textstellen markiert",
 	"pulse_reviewed": "Textstellen transkribiert",
 	"pulse_uploaded": "Dokumente hochgeladen",
-
 	"feed_caption": "Kommentare & Aktivität",
 	"feed_show_all": "Alle anzeigen",
 	"feed_for_you": "für dich",
-
 	"audit_action_text_saved": "hat Text gespeichert in",
 	"audit_action_file_uploaded": "hat eine Datei hochgeladen:",
 	"audit_action_annotation_created": "hat eine Markierung erstellt in",
 	"audit_action_comment_added": "hat kommentiert:",
 	"audit_action_mention_created": "hat dich erwähnt in",
-
 	"dropzone_release": "Loslassen zum Hochladen",
-
 	"chronik_page_title": "Aktivitäten",
 	"chronik_for_you_caption": "Für dich",
 	"chronik_for_you_count": "{count} neu",
@@ -859,9 +850,7 @@
 	"pagination_page_of": "Seite {page} von {total}",
 	"pagination_nav_label": "Seitennavigation",
 	"pagination_page_button": "Seite {page}",
-
 	"common_opens_new_tab": "(öffnet in neuem Tab)",
-
 	"transcribe_coach_title": "Erste Transkription?",
 	"transcribe_coach_preamble": "Unser Kurrent-Erkenner lernt noch. Jede Transkription, die Sie zum Training freigeben, bringt ihm die Schrift bei — so funktioniert's:",
 	"transcribe_coach_step_1_title": "Rahmen ziehen.",
@@ -871,10 +860,8 @@
 	"transcribe_coach_step_3_title": "Speichert automatisch.",
 	"transcribe_coach_footer_kurrent": "Hilfe zu Kurrent ↗",
 	"transcribe_coach_footer_richtlinien": "Transkriptions-Richtlinien ↗",
-
 	"transcription_mode_help_label": "Lese- und Bearbeitungsmodus",
 	"transcription_mode_help_body": "Lesen zeigt die Transkription als fließenden Text. Bearbeiten öffnet die Textfelder für jede Passage.",
-
 	"richtlinien_title": "Transkriptions-Richtlinien",
 	"richtlinien_intro": "Damit alle Briefe einheitlich transkribiert werden — egal wer tippt — hier unsere Regeln. Die Seite wächst mit: sobald wir eine neue Konvention beschließen, landet sie hier.",
 	"richtlinien_wiki_text": "Kurrent- und Sütterlin-Alphabete sind bei Wikipedia gut erklärt. Hier stehen nur unsere eigenen Vereinbarungen für dieses Archiv.",
@@ -948,12 +935,9 @@
 	"bulk_edit_all_x_failed": "Filter konnte nicht abgerufen werden — bitte erneut versuchen.",
 	"bulk_edit_topbar_title": "Massenbearbeitung",
 	"bulk_edit_count_pill": "{count} werden bearbeitet",
-
 	"nav_stammbaum": "Stammbaum",
 	"nav_geschichten": "Geschichten",
-
 	"error_geschichte_not_found": "Die Geschichte wurde nicht gefunden.",
-
 	"geschichten_index_title": "Geschichten",
 	"geschichten_new_button": "Neue Geschichte",
 	"geschichten_filter_all_pill": "Alle",
@@ -973,7 +957,6 @@
 	"geschichten_card_attach_action": "+ Geschichte anhängen",
 	"geschichten_card_show_all_for_person": "Alle Geschichten zu {name}",
 	"geschichten_card_show_all": "Alle anzeigen",
-
 	"geschichte_editor_title_placeholder": "Titel der Geschichte",
 	"geschichte_editor_body_placeholder": "Schreibe hier deine Geschichte…",
 	"geschichte_editor_status_draft": "ENTWURF",
@@ -1000,14 +983,11 @@
 	"geschichte_editor_toolbar_h3": "Unterüberschrift",
 	"geschichte_editor_toolbar_ul": "Aufzählung",
 	"geschichte_editor_toolbar_ol": "Nummerierte Liste",
-
 	"geschichte_delete_confirm_title": "Geschichte löschen?",
 	"geschichte_delete_confirm_body": "Diese Aktion kann nicht rückgängig gemacht werden. Die Geschichte wird dauerhaft gelöscht und aus allen verlinkten Personen- und Dokumentseiten entfernt.",
-
 	"error_relationship_not_found": "Die Beziehung wurde nicht gefunden.",
 	"error_circular_relationship": "Diese Beziehung würde einen Kreis erzeugen.",
 	"error_duplicate_relationship": "Diese Beziehung gibt es bereits.",
-
 	"relation_parent_of": "Elternteil von",
 	"relation_child_of": "Kind von",
 	"relation_spouse_of": "Ehegatte",
@@ -1018,7 +998,6 @@
 	"relation_doctor": "Arzt",
 	"relation_neighbor": "Nachbar",
 	"relation_other": "Sonstige",
-
 	"relation_inferred_parent": "Elternteil",
 	"relation_inferred_child": "Kind",
 	"relation_inferred_spouse": "Ehegatte",
@@ -1036,9 +1015,7 @@
 	"relation_inferred_sibling_inlaw": "Schwager/Schwägerin",
 	"relation_inferred_cousin_1": "Cousin/Cousine",
 	"relation_inferred_distant": "Weitläufige Verwandtschaft",
-
 	"doc_details_field_relationship": "Verwandtschaft",
-
 	"stammbaum_empty_heading": "Noch keine Familienmitglieder",
 	"stammbaum_empty_body": "Markiere Personen auf ihrer Bearbeitungsseite als Familienmitglied, damit sie hier erscheinen.",
 	"stammbaum_empty_link": "→ Zur Personenliste",
@@ -1050,7 +1027,6 @@
 	"stammbaum_zoom_in": "Vergrößern",
 	"stammbaum_zoom_out": "Verkleinern",
 	"stammbaum_generations": "Generationen",
-
 	"relation_error_duplicate": "Diese Beziehung gibt es bereits.",
 	"relation_error_circular": "Diese Beziehung würde einen Kreis erzeugen.",
 	"relation_error_self": "Eine Person kann nicht mit sich selbst verbunden werden.",
@@ -1073,14 +1049,15 @@
 	"relation_form_field_from_year": "Von Jahr",
 	"relation_form_field_to_year": "Bis Jahr",
 	"relation_form_year_placeholder": "z.B. 1920",
-
 	"person_relationships_heading": "Beziehungen",
 	"person_relationships_empty": "Noch keine Beziehungen bekannt.",
-
 	"timeline_aria_label": "Zeitachse Dokumentdichte",
 	"timeline_clear_selection": "Auswahl zurücksetzen",
 	"timeline_zoom_reset": "Zurück zur Übersicht",
 	"timeline_bar_aria_singular": "{when}, 1 Dokument",
 	"timeline_bar_aria_plural": "{when}, {count} Dokumente",
-	"timeline_dragging_aria_live": "Zeitraum {from} bis {to} ausgewählt"
+	"timeline_dragging_aria_live": "Zeitraum {from} bis {to} ausgewählt",
+	"error_page_id_label": "Fehler-ID",
+	"error_copy_id_label": "ID kopieren",
+	"error_copied": "Kopiert!"
 }

frontend/messages/en.json

@@ -473,7 +473,7 @@
 	"dashboard_reader_stats_persons_short": "Pers.",
 	"dashboard_reader_stats_stories_short": "Stor.",
 	"dashboard_reader_draft_meta": "Draft · last edited {relative}",
-	"dashboard_resume_label": "Last opened:",
+	"dashboard_resume_label": "Continue where you left off",
 	"dashboard_resume_fallback": "Unknown document",
 	"doc_status_placeholder": "Placeholder",
 	"doc_status_uploaded": "Uploaded",
@@ -773,19 +773,15 @@
 	"admin_invite_created_title": "Invite created",
 	"admin_invite_created_desc": "Share this link with the person you are inviting:",
 	"admin_invite_revoke_confirm": "Really revoke this invite?",
-
 	"greeting_morning": "Good morning, {name}.",
 	"greeting_day": "Hello, {name}.",
 	"greeting_evening": "Good evening, {name}.",
-
-	"dashboard_resume_label": "Continue where you left off",
 	"dashboard_blocks": "{count} sections",
 	"dashboard_resume_cta": "Continue transcribing",
 	"dashboard_resume_other": "or choose another document",
 	"dashboard_empty_title": "No document started yet",
 	"dashboard_empty_body": "Choose a document from the archive to start transcribing.",
 	"dashboard_empty_cta": "To the archive",
-
 	"dashboard_mission_caption": "Open tasks",
 	"queue_segment": "Segment",
 	"queue_segment_blurb": "Split pages",
@@ -795,7 +791,6 @@
 	"queue_review_blurb": "Check texts",
 	"queue_n_open": "{n} open",
 	"queue_show_all": "Show all →",
-
 	"pulse_eyebrow": "This week",
 	"pulse_headline": "You have worked on {pages} pages.",
 	"pulse_you": "You personally worked on {pages} of them.",
@@ -803,19 +798,15 @@
 	"pulse_transcribed": "Passages annotated",
 	"pulse_reviewed": "Passages transcribed",
 	"pulse_uploaded": "Documents uploaded",
-
 	"feed_caption": "Comments & activity",
 	"feed_show_all": "Show all",
 	"feed_for_you": "for you",
-
 	"audit_action_text_saved": "saved text in",
 	"audit_action_file_uploaded": "uploaded a file:",
 	"audit_action_annotation_created": "created an annotation in",
 	"audit_action_comment_added": "commented:",
 	"audit_action_mention_created": "mentioned you in",
-
 	"dropzone_release": "Release to upload",
-
 	"chronik_page_title": "Activity",
 	"chronik_for_you_caption": "For you",
 	"chronik_for_you_count": "{count} new",
@@ -859,9 +850,7 @@
 	"pagination_page_of": "Page {page} of {total}",
 	"pagination_nav_label": "Pagination",
 	"pagination_page_button": "Page {page}",
-
 	"common_opens_new_tab": "(opens in new tab)",
-
 	"transcribe_coach_title": "First transcription?",
 	"transcribe_coach_preamble": "Our Kurrent recogniser is still learning. Every transcription you release for training teaches it the handwriting — here's how it works:",
 	"transcribe_coach_step_1_title": "Draw a frame.",
@@ -871,10 +860,8 @@
 	"transcribe_coach_step_3_title": "Saves automatically.",
 	"transcribe_coach_footer_kurrent": "Kurrent help ↗",
 	"transcribe_coach_footer_richtlinien": "Transcription guidelines ↗",
-
 	"transcription_mode_help_label": "Read and edit mode",
 	"transcription_mode_help_body": "Read shows the transcription as flowing text. Edit opens the text fields for each passage.",
-
 	"richtlinien_title": "Transcription Guidelines",
 	"richtlinien_intro": "So every letter is transcribed consistently — no matter who types — here are our rules. The page grows with us: as soon as we agree a new convention, it lands here.",
 	"richtlinien_wiki_text": "The Kurrent and Sütterlin alphabets are well explained on Wikipedia. Here you'll only find our own conventions for this archive.",
@@ -948,12 +935,9 @@
 	"bulk_edit_all_x_failed": "Could not load filter results — please retry.",
 	"bulk_edit_topbar_title": "Bulk edit",
 	"bulk_edit_count_pill": "{count} will be edited",
-
 	"nav_stammbaum": "Family tree",
 	"nav_geschichten": "Stories",
-
 	"error_geschichte_not_found": "The story was not found.",
-
 	"geschichten_index_title": "Stories",
 	"geschichten_new_button": "New story",
 	"geschichten_filter_all_pill": "All",
@@ -973,7 +957,6 @@
 	"geschichten_card_attach_action": "+ Attach a story",
 	"geschichten_card_show_all_for_person": "All stories about {name}",
 	"geschichten_card_show_all": "Show all",
-
 	"geschichte_editor_title_placeholder": "Story title",
 	"geschichte_editor_body_placeholder": "Write your story here…",
 	"geschichte_editor_status_draft": "DRAFT",
@@ -1000,14 +983,11 @@
 	"geschichte_editor_toolbar_h3": "Subheading",
 	"geschichte_editor_toolbar_ul": "Bulleted list",
 	"geschichte_editor_toolbar_ol": "Numbered list",
-
 	"geschichte_delete_confirm_title": "Delete story?",
 	"geschichte_delete_confirm_body": "This action cannot be undone. The story will be permanently deleted and removed from all linked person and document pages.",
-
 	"error_relationship_not_found": "Relationship not found.",
 	"error_circular_relationship": "This relationship would form a cycle.",
 	"error_duplicate_relationship": "This relationship already exists.",
-
 	"relation_parent_of": "Parent of",
 	"relation_child_of": "Child of",
 	"relation_spouse_of": "Spouse",
@@ -1018,7 +998,6 @@
 	"relation_doctor": "Doctor",
 	"relation_neighbor": "Neighbour",
 	"relation_other": "Other",
-
 	"relation_inferred_parent": "Parent",
 	"relation_inferred_child": "Child",
 	"relation_inferred_spouse": "Spouse",
@@ -1036,9 +1015,7 @@
 	"relation_inferred_sibling_inlaw": "Sibling-in-law",
 	"relation_inferred_cousin_1": "Cousin",
 	"relation_inferred_distant": "Distant relative",
-
 	"doc_details_field_relationship": "Relationship",
-
 	"stammbaum_empty_heading": "No family members yet",
 	"stammbaum_empty_body": "Mark a person as a family member on their edit page so they appear here.",
 	"stammbaum_empty_link": "→ Go to person list",
@@ -1050,7 +1027,6 @@
 	"stammbaum_zoom_in": "Zoom in",
 	"stammbaum_zoom_out": "Zoom out",
 	"stammbaum_generations": "Generations",
-
 	"relation_error_duplicate": "This relationship already exists.",
 	"relation_error_circular": "This relationship would form a cycle.",
 	"relation_error_self": "A person cannot be related to themselves.",
@@ -1073,14 +1049,15 @@
 	"relation_form_field_from_year": "From year",
 	"relation_form_field_to_year": "To year",
 	"relation_form_year_placeholder": "e.g. 1920",
-
 	"person_relationships_heading": "Relationships",
 	"person_relationships_empty": "No relationships known yet.",
-
 	"timeline_aria_label": "Document density timeline",
 	"timeline_clear_selection": "Clear selection",
 	"timeline_zoom_reset": "Reset zoom",
 	"timeline_bar_aria_singular": "{when}, 1 document",
 	"timeline_bar_aria_plural": "{when}, {count} documents",
-	"timeline_dragging_aria_live": "Range {from} to {to} selected"
+	"timeline_dragging_aria_live": "Range {from} to {to} selected",
+	"error_page_id_label": "Error ID",
+	"error_copy_id_label": "Copy ID",
+	"error_copied": "Copied!"
 }

frontend/messages/es.json

@@ -473,7 +473,7 @@
 	"dashboard_reader_stats_persons_short": "Pers.",
 	"dashboard_reader_stats_stories_short": "Hist.",
 	"dashboard_reader_draft_meta": "Borrador · editado hace {relative}",
-	"dashboard_resume_label": "Último abierto:",
+	"dashboard_resume_label": "Continuar donde lo dejaste",
 	"dashboard_resume_fallback": "Documento desconocido",
 	"doc_status_placeholder": "Marcador",
 	"doc_status_uploaded": "Cargado",
@@ -773,19 +773,15 @@
 	"admin_invite_created_title": "Invitación creada",
 	"admin_invite_created_desc": "Comparte este enlace con la persona invitada:",
 	"admin_invite_revoke_confirm": "¿Realmente revocar esta invitación?",
-
 	"greeting_morning": "Buenos días, {name}.",
 	"greeting_day": "Hola, {name}.",
 	"greeting_evening": "Buenas noches, {name}.",
-
-	"dashboard_resume_label": "Continuar donde lo dejaste",
 	"dashboard_blocks": "{count} secciones",
 	"dashboard_resume_cta": "Continuar transcripción",
 	"dashboard_resume_other": "o elige otro documento",
 	"dashboard_empty_title": "Aún no has comenzado ningún documento",
 	"dashboard_empty_body": "Elige un documento del archivo para empezar a transcribir.",
 	"dashboard_empty_cta": "Al archivo",
-
 	"dashboard_mission_caption": "Tareas pendientes",
 	"queue_segment": "Segmentar",
 	"queue_segment_blurb": "Dividir páginas",
@@ -795,7 +791,6 @@
 	"queue_review_blurb": "Controlar textos",
 	"queue_n_open": "{n} pendiente",
 	"queue_show_all": "Ver todo →",
-
 	"pulse_eyebrow": "Esta semana",
 	"pulse_headline": "Habéis trabajado {pages} páginas.",
 	"pulse_you": "Tú mismo has trabajado {pages} de ellas.",
@@ -803,19 +798,15 @@
 	"pulse_transcribed": "Fragmentos anotados",
 	"pulse_reviewed": "Fragmentos transcritos",
 	"pulse_uploaded": "Documentos subidos",
-
 	"feed_caption": "Comentarios y actividad",
 	"feed_show_all": "Ver todo",
 	"feed_for_you": "para ti",
-
 	"audit_action_text_saved": "guardó texto en",
 	"audit_action_file_uploaded": "subió un archivo:",
 	"audit_action_annotation_created": "creó una anotación en",
 	"audit_action_comment_added": "comentó:",
 	"audit_action_mention_created": "te mencionó en",
-
 	"dropzone_release": "Suelta para subir",
-
 	"chronik_page_title": "Actividades",
 	"chronik_for_you_caption": "Para ti",
 	"chronik_for_you_count": "{count} nuevas",
@@ -859,9 +850,7 @@
 	"pagination_page_of": "Página {page} de {total}",
 	"pagination_nav_label": "Paginación",
 	"pagination_page_button": "Página {page}",
-
 	"common_opens_new_tab": "(abre en pestaña nueva)",
-
 	"transcribe_coach_title": "¿Primera transcripción?",
 	"transcribe_coach_preamble": "Nuestro reconocedor de Kurrent aún está aprendiendo. Cada transcripción que libera para el entrenamiento le enseña la escritura — así funciona:",
 	"transcribe_coach_step_1_title": "Dibujar un marco.",
@@ -871,10 +860,8 @@
 	"transcribe_coach_step_3_title": "Se guarda automáticamente.",
 	"transcribe_coach_footer_kurrent": "Ayuda sobre Kurrent ↗",
 	"transcribe_coach_footer_richtlinien": "Normas de transcripción ↗",
-
 	"transcription_mode_help_label": "Modo lectura y edición",
 	"transcription_mode_help_body": "Lectura muestra la transcripción como texto continuo. Edición abre los campos de texto para cada pasaje.",
-
 	"richtlinien_title": "Normas de transcripción",
 	"richtlinien_intro": "Para que todas las cartas se transcriban de forma uniforme — sin importar quién transcriba — aquí están nuestras reglas. La página crece con nosotros.",
 	"richtlinien_wiki_text": "Los alfabetos Kurrent y Sütterlin están bien explicados en Wikipedia. Aquí solo se recogen nuestros propios acuerdos para este archivo.",
@@ -948,12 +935,9 @@
 	"bulk_edit_all_x_failed": "No se pudieron cargar los resultados del filtro; vuelve a intentarlo.",
 	"bulk_edit_topbar_title": "Edición masiva",
 	"bulk_edit_count_pill": "Se editarán {count}",
-
 	"nav_stammbaum": "Árbol genealógico",
 	"nav_geschichten": "Historias",
-
 	"error_geschichte_not_found": "No se encontró la historia.",
-
 	"geschichten_index_title": "Historias",
 	"geschichten_new_button": "Nueva historia",
 	"geschichten_filter_all_pill": "Todas",
@@ -973,7 +957,6 @@
 	"geschichten_card_attach_action": "+ Adjuntar historia",
 	"geschichten_card_show_all_for_person": "Todas las historias sobre {name}",
 	"geschichten_card_show_all": "Mostrar todas",
-
 	"geschichte_editor_title_placeholder": "Título de la historia",
 	"geschichte_editor_body_placeholder": "Escribe tu historia aquí…",
 	"geschichte_editor_status_draft": "BORRADOR",
@@ -1000,14 +983,11 @@
 	"geschichte_editor_toolbar_h3": "Subencabezado",
 	"geschichte_editor_toolbar_ul": "Lista con viñetas",
 	"geschichte_editor_toolbar_ol": "Lista numerada",
-
 	"geschichte_delete_confirm_title": "¿Eliminar historia?",
 	"geschichte_delete_confirm_body": "Esta acción no se puede deshacer. La historia se eliminará permanentemente y se quitará de todas las páginas de personas y documentos vinculados.",
-
 	"error_relationship_not_found": "La relación no fue encontrada.",
 	"error_circular_relationship": "Esta relación crearía un ciclo.",
 	"error_duplicate_relationship": "Esta relación ya existe.",
-
 	"relation_parent_of": "Progenitor de",
 	"relation_child_of": "Hijo/a de",
 	"relation_spouse_of": "Cónyuge",
@@ -1018,7 +998,6 @@
 	"relation_doctor": "Médico",
 	"relation_neighbor": "Vecino/a",
 	"relation_other": "Otro",
-
 	"relation_inferred_parent": "Progenitor",
 	"relation_inferred_child": "Hijo/a",
 	"relation_inferred_spouse": "Cónyuge",
@@ -1036,9 +1015,7 @@
 	"relation_inferred_sibling_inlaw": "Cuñado/a",
 	"relation_inferred_cousin_1": "Primo/a",
 	"relation_inferred_distant": "Pariente lejano",
-
 	"doc_details_field_relationship": "Parentesco",
-
 	"stammbaum_empty_heading": "Aún no hay miembros de la familia",
 	"stammbaum_empty_body": "Marca a una persona como miembro de la familia en su página de edición para que aparezca aquí.",
 	"stammbaum_empty_link": "→ Ir a la lista de personas",
@@ -1050,7 +1027,6 @@
 	"stammbaum_zoom_in": "Acercar",
 	"stammbaum_zoom_out": "Alejar",
 	"stammbaum_generations": "Generaciones",
-
 	"relation_error_duplicate": "Esta relación ya existe.",
 	"relation_error_circular": "Esta relación crearía un ciclo.",
 	"relation_error_self": "Una persona no puede estar relacionada consigo misma.",
@@ -1073,14 +1049,15 @@
 	"relation_form_field_from_year": "Desde año",
 	"relation_form_field_to_year": "Hasta año",
 	"relation_form_year_placeholder": "ej. 1920",
-
 	"person_relationships_heading": "Relaciones",
 	"person_relationships_empty": "Aún no se conocen relaciones.",
-
 	"timeline_aria_label": "Cronología de densidad de documentos",
 	"timeline_clear_selection": "Borrar selección",
 	"timeline_zoom_reset": "Restablecer zoom",
 	"timeline_bar_aria_singular": "{when}, 1 documento",
 	"timeline_bar_aria_plural": "{when}, {count} documentos",
-	"timeline_dragging_aria_live": "Rango {from} a {to} seleccionado"
+	"timeline_dragging_aria_live": "Rango {from} a {to} seleccionado",
+	"error_page_id_label": "ID de error",
+	"error_copy_id_label": "Copiar ID",
+	"error_copied": "¡Copiado!"
 }

frontend/src/app.d.ts

@@ -26,6 +26,11 @@ declare global {
 		interface PageData {
 			user?: User; // Available in $page.data.user
 		}
+
+		interface Error {
+			message: string;
+			errorId?: string;
+		}
 	}
 }
 

frontend/src/hooks.client.test.ts

@@ -0,0 +1,47 @@
+import { describe, it, expect, vi, beforeEach } from 'vitest';
+
+vi.mock('@sentry/sveltekit', () => ({
+	init: vi.fn(),
+	handleErrorWithSentry: (fn: (args: unknown) => unknown) => fn,
+	lastEventId: vi.fn(() => 'sentry-event-id-abc123')
+}));
+
+describe('hooks.client handleError', () => {
+	beforeEach(() => {
+		vi.resetModules();
+	});
+
+	it('returns Sentry lastEventId as errorId', async () => {
+		const Sentry = await import('@sentry/sveltekit');
+		vi.mocked(Sentry.lastEventId).mockReturnValue('sentry-event-id-abc123');
+
+		const { handleError } = await import('./hooks.client');
+		const result = (handleError as (args: unknown) => { message: string; errorId: string })({
+			error: new Error('boom'),
+			event: {},
+			status: 500,
+			message: 'Internal Error'
+		});
+
+		expect(result.errorId).toBe('sentry-event-id-abc123');
+		expect(result.message).toBe('An unexpected error occurred');
+	});
+
+	it('falls back to crypto.randomUUID when lastEventId returns undefined', async () => {
+		const Sentry = await import('@sentry/sveltekit');
+		vi.mocked(Sentry.lastEventId).mockReturnValue(undefined);
+
+		const { handleError } = await import('./hooks.client');
+		const result = (handleError as (args: unknown) => { message: string; errorId: string })({
+			error: new Error('boom'),
+			event: {},
+			status: 500,
+			message: 'Internal Error'
+		});
+
+		expect(result.errorId).toMatch(
+			/^[0-9a-f]{8}-[0-9a-f]{4}-[0-9a-f]{4}-[0-9a-f]{4}-[0-9a-f]{12}$/
+		);
+		expect(result.message).toBe('An unexpected error occurred');
+	});
+});

frontend/src/hooks.client.ts

@@ -1,10 +1,16 @@
 import * as Sentry from '@sentry/sveltekit';
 
+// VITE_SENTRY_DSN is a write-only ingest key — it can POST events to GlitchTip
+// but cannot read them. Safe to include in the client bundle per Sentry security model.
 Sentry.init({
 	dsn: import.meta.env.VITE_SENTRY_DSN,
 	environment: import.meta.env.MODE,
-	tracesSampleRate: 1.0,
+	tracesSampleRate: 0.1,
+	sendDefaultPii: false,
 	enabled: !!import.meta.env.VITE_SENTRY_DSN
 });
 
-export const handleError = Sentry.handleErrorWithSentry();
+export const handleError = Sentry.handleErrorWithSentry(() => {
+	const errorId = Sentry.lastEventId() ?? crypto.randomUUID();
+	return { message: 'An unexpected error occurred', errorId };
+});

frontend/src/hooks.server.test.ts

@@ -0,0 +1,58 @@
+import { describe, it, expect, vi, beforeEach } from 'vitest';
+
+vi.mock('@sentry/sveltekit', () => ({
+	init: vi.fn(),
+	handleErrorWithSentry: (fn: (args: unknown) => unknown) => fn,
+	lastEventId: vi.fn(() => 'sentry-event-id-abc123')
+}));
+
+vi.mock('@sveltejs/kit', () => ({ redirect: vi.fn() }));
+vi.mock('@sveltejs/kit/hooks', () => ({ sequence: vi.fn((...fns: unknown[]) => fns[0]) }));
+vi.mock('$lib/paraglide/server', () => ({ paraglideMiddleware: vi.fn() }));
+vi.mock('$lib/paraglide/runtime', () => ({ cookieName: 'locale', cookieMaxAge: 86400 }));
+vi.mock('$lib/shared/server/locale', () => ({ detectLocale: vi.fn(() => 'de') }));
+
+const makeEvent = () => ({
+	url: { pathname: '/documents/123' },
+	locals: {}
+});
+
+describe('hooks.server handleError', () => {
+	beforeEach(() => {
+		vi.resetModules();
+	});
+
+	it('returns Sentry lastEventId as errorId', async () => {
+		const Sentry = await import('@sentry/sveltekit');
+		vi.mocked(Sentry.lastEventId).mockReturnValue('sentry-event-id-abc123');
+
+		const { handleError } = await import('./hooks.server');
+		const result = (handleError as (args: unknown) => { message: string; errorId: string })({
+			error: new Error('boom'),
+			event: makeEvent(),
+			status: 500,
+			message: 'Internal Error'
+		});
+
+		expect(result.errorId).toBe('sentry-event-id-abc123');
+		expect(result.message).toBe('An unexpected error occurred');
+	});
+
+	it('falls back to crypto.randomUUID when lastEventId returns undefined', async () => {
+		const Sentry = await import('@sentry/sveltekit');
+		vi.mocked(Sentry.lastEventId).mockReturnValue(undefined);
+
+		const { handleError } = await import('./hooks.server');
+		const result = (handleError as (args: unknown) => { message: string; errorId: string })({
+			error: new Error('boom'),
+			event: makeEvent(),
+			status: 500,
+			message: 'Internal Error'
+		});
+
+		expect(result.errorId).toMatch(
+			/^[0-9a-f]{8}-[0-9a-f]{4}-[0-9a-f]{4}-[0-9a-f]{4}-[0-9a-f]{12}$/
+		);
+		expect(result.message).toBe('An unexpected error occurred');
+	});
+});

frontend/src/hooks.server.ts

@@ -6,10 +6,13 @@ import { env } from 'process';
 import { cookieName, cookieMaxAge } from '$lib/paraglide/runtime';
 import { detectLocale } from '$lib/shared/server/locale';
 
+// VITE_SENTRY_DSN is a write-only ingest key — it can POST events to GlitchTip
+// but cannot read them. Safe to include in the client bundle per Sentry security model.
 Sentry.init({
 	dsn: import.meta.env.VITE_SENTRY_DSN,
 	environment: import.meta.env.MODE,
-	tracesSampleRate: 1.0,
+	tracesSampleRate: 0.1,
+	sendDefaultPii: false,
 	enabled: !!import.meta.env.VITE_SENTRY_DSN
 });
 
@@ -122,4 +125,7 @@ export const handleFetch: HandleFetch = async ({ event, request, fetch }) => {
 
 export const handle = sequence(userGroup, handleAuth, handleLocaleDetection, handleParaglide);
 
-export const handleError = Sentry.handleErrorWithSentry();
+export const handleError = Sentry.handleErrorWithSentry(() => {
+	const errorId = Sentry.lastEventId() ?? crypto.randomUUID();
+	return { message: 'An unexpected error occurred', errorId };
+});

frontend/src/routes/+error.svelte

@@ -1,13 +1,53 @@
 <script lang="ts">
 import { page } from '$app/state';
 import { m } from '$lib/paraglide/messages.js';
+
+let copied = $state(false);
+
+function copyId() {
+	const id = page.error?.errorId;
+	if (!id) return;
+	if (!navigator.clipboard) return;
+	navigator.clipboard.writeText(id).then(
+		() => {
+			copied = true;
+			setTimeout(() => (copied = false), 2000);
+		},
+		() => {
+			/* clipboard denied or unavailable — select-all on the <code> element remains */
+		}
+	);
+}
 </script>
 
 <svelte:head>
 	<title>{m.page_title_error()}</title>
 </svelte:head>
 
-<div class="px-4 py-12 text-center font-sans">
+<main class="px-4 py-12 text-center font-sans">
-	<p class="font-sans text-6xl font-bold text-ink">{page.status}</p>
+	<h1 class="mb-2 font-serif text-2xl font-bold text-ink">{m.page_title_error()}</h1>
-	<p class="mt-2 font-sans text-sm text-ink-2">{page.error?.message ?? 'Internal Error'}</p>
+	<p class="mb-8 font-sans text-sm text-ink-2">
-</div>
+		{page.error?.message ?? m.error_internal_error()}
+	</p>
+	<p class="mb-4 font-mono text-4xl font-bold text-ink">{page.status}</p>
+
+	{#if page.error?.errorId}
+		<div class="mt-6 flex flex-col items-center gap-3">
+			<p class="font-sans text-xs tracking-widest text-ink-2 uppercase">
+				{m.error_page_id_label()}
+			</p>
+			<code
+				class="rounded border border-line bg-surface px-3 py-1 font-mono text-sm text-ink select-all"
+			>
+				{page.error.errorId}
+			</code>
+			<button
+				class="min-h-[44px] min-w-[44px] rounded-sm bg-brand-navy px-5 py-2 font-sans text-sm text-white transition-colors hover:opacity-90 focus-visible:ring-2 focus-visible:ring-brand-navy focus-visible:ring-offset-2"
+				onclick={copyId}
+				aria-label={m.error_copy_id_label()}
+			>
+				<span aria-live="polite">{copied ? m.error_copied() : m.error_copy_id_label()}</span>
+			</button>
+		</div>
+	{/if}
+</main>

frontend/src/routes/api/tags/+server.ts

@@ -24,7 +24,6 @@ export const GET: RequestHandler = async ({ url, fetch }) => {
 		}
 
 		const data = await response.json();
-		console.log('Tags Data', data);
 
 		// 4. Daten zurück an den Browser schicken
 		return json(data);

frontend/src/routes/error.svelte.test.ts

@@ -4,7 +4,10 @@ import { page as browserPage } from 'vitest/browser';
 
 const mockPage = {
 	status: 500,
-	error: { message: 'Internal Error' } as { message: string } | null
+	error: { message: 'Internal Error', errorId: undefined } as {
+		message: string;
+		errorId?: string;
+	} | null
 };
 
 vi.mock('$app/state', () => ({
@@ -13,6 +16,16 @@ vi.mock('$app/state', () => ({
 	}
 }));
 
+vi.mock('$lib/paraglide/messages.js', () => ({
+	m: {
+		page_title_error: () => 'Es ist etwas schiefgelaufen.',
+		error_internal_error: () => 'Ein unerwarteter Fehler ist aufgetreten.',
+		error_page_id_label: () => 'Fehler-ID',
+		error_copy_id_label: () => 'ID kopieren',
+		error_copied: () => 'Kopiert!'
+	}
+}));
+
 afterEach(cleanup);
 
 async function loadComponent() {
@@ -20,7 +33,7 @@ async function loadComponent() {
 }
 
 describe('+error.svelte', () => {
-	it('renders the page status code prominently', async () => {
+	it('renders the page status code', async () => {
 		mockPage.status = 404;
 		mockPage.error = { message: 'Not Found' };
 
@@ -40,13 +53,79 @@ describe('+error.svelte', () => {
 		await expect.element(browserPage.getByText('Database unavailable')).toBeVisible();
 	});
 
-	it('falls back to the literal "Internal Error" when page.error is null', async () => {
+	it('falls back to error_internal_error message when page.error is null', async () => {
 		mockPage.status = 500;
 		mockPage.error = null;
 
 		const ErrorPage = await loadComponent();
 		render(ErrorPage);
 
-		await expect.element(browserPage.getByText('Internal Error')).toBeVisible();
+		await expect
+			.element(browserPage.getByText('Ein unerwarteter Fehler ist aufgetreten.'))
+			.toBeVisible();
+	});
+
+	it('shows errorId when page.error.errorId is set', async () => {
+		mockPage.status = 500;
+		mockPage.error = { message: 'Something broke', errorId: 'abc-123-def' };
+
+		const ErrorPage = await loadComponent();
+		render(ErrorPage);
+
+		await expect.element(browserPage.getByText('abc-123-def')).toBeVisible();
+	});
+
+	it('shows copy button when errorId is present', async () => {
+		mockPage.status = 500;
+		mockPage.error = { message: 'Something broke', errorId: 'abc-123-def' };
+
+		const ErrorPage = await loadComponent();
+		render(ErrorPage);
+
+		await expect.element(browserPage.getByRole('button', { name: 'ID kopieren' })).toBeVisible();
+	});
+
+	it('does not render errorId section when errorId is absent', async () => {
+		mockPage.status = 500;
+		mockPage.error = { message: 'Something broke' };
+
+		const ErrorPage = await loadComponent();
+		render(ErrorPage);
+
+		await expect.element(browserPage.getByText('Fehler-ID')).not.toBeInTheDocument();
+	});
+
+	it('shows "Kopiert!" after clicking the copy button', async () => {
+		mockPage.status = 500;
+		mockPage.error = { message: 'Something broke', errorId: 'abc-123-def' };
+
+		Object.defineProperty(navigator, 'clipboard', {
+			value: { writeText: vi.fn().mockResolvedValue(undefined) },
+			configurable: true,
+			writable: true
+		});
+
+		const ErrorPage = await loadComponent();
+		render(ErrorPage);
+
+		await browserPage.getByRole('button', { name: 'ID kopieren' }).click();
+		await expect.element(browserPage.getByText('Kopiert!')).toBeVisible();
+	});
+
+	it('does not show "Kopiert!" when clipboard write is rejected', async () => {
+		mockPage.status = 500;
+		mockPage.error = { message: 'Something broke', errorId: 'abc-123-def' };
+
+		Object.defineProperty(navigator, 'clipboard', {
+			value: { writeText: vi.fn().mockRejectedValue(new Error('denied')) },
+			configurable: true,
+			writable: true
+		});
+
+		const ErrorPage = await loadComponent();
+		render(ErrorPage);
+
+		await browserPage.getByRole('button', { name: 'ID kopieren' }).click();
+		await expect.element(browserPage.getByText('Kopiert!')).not.toBeInTheDocument();
 	});
 });

frontend/vite.config.ts

@@ -71,7 +71,8 @@ export default defineConfig({
 				'src/lib/shared/utils/**',
 				'src/lib/shared/server/**',
 				'src/lib/shared/discussion/**',
-				'src/lib/document/**'
+				'src/lib/document/**',
+				'src/hooks.server.ts'
 			],
 			exclude: ['**/*.svelte', '**/*.svelte.ts', '**/__mocks__/**'],
 			thresholds: {