docs: anleitung, changelog 0.3.0 und roadmap zu phase 3

Vier neue Kapitel in der Anleitung (mehrere Sammler, Preise,
Erinnerungen, Dubletten) mit vier automatisch erzeugten Bildern,
Changelog 0.3.0 samt der bewusst weggelassenen BrickLink-Anbindung,
Roadmap abgehakt und um einen offenen Ausblick ergaenzt, Devlog mit
Zeiten und Stolpersteinen.

Dazu zwei Korrekturen aus dem Testlauf:

Der Zeitplan fuer Erinnerungen liess sich nicht aus Next'
instrumentation.ts starten - die Datei wird auch fuer die Edge-Runtime
uebersetzt, und das native SQLite-Modul bricht dort den Build. Er
startet jetzt aus dem Healthcheck heraus, den der Container ohnehin alle
30 Sekunden aufruft, und zusaetzlich aus dem App-Layout; der Aufruf ist
idempotent.

Der Screenshot-Lauf waehlte ploetzlich die falschen Kacheln aus: Der
neue Sammler-Umschalter benutzt ebenfalls aria-pressed. Die
Auswahlkacheln tragen jetzt ein eigenes data-set-card.

Ausserdem raeumen die Testskripte einen Container weg, den ein
abgebrochener Lauf zurueckgelassen hat - sonst blockiert er den Port.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

.env.example

@@ -32,3 +32,16 @@ TZ=Europe/Berlin
 # und Bild werden uebernommen. Ohne Key funktioniert alles manuell weiter.
 # Kostenlos anlegen: https://rebrickable.com/api/ (Konto -> Settings -> API)
 # REBRICKABLE_API_KEY=
+
+# Optional: Mailversand fuer Erinnerungen an Wunschlisten-Termine. Ohne
+# SMTP_HOST und SMTP_FROM sind Erinnerungen komplett aus - alles andere
+# funktioniert unveraendert.
+# SMTP_HOST=mail.example.de
+# SMTP_PORT=587
+# SMTP_SECURE=false
+# SMTP_USER=bricktrack@example.de
+# SMTP_PASSWORD=
+# SMTP_FROM=Bricktrack <bricktrack@example.de>
+
+# Wie viele Tage vor dem Termin erinnert wird (Standard: 14).
+# REMINDER_DAYS_BEFORE=14

CHANGELOG.md

@@ -7,6 +7,53 @@ die Versionierung [Semantic Versioning](https://semver.org/lang/de/).
 
 ## [Unreleased]
 
+## [0.3.0] - 2026-09-07
+
+Phase 3: mehrere Kinder, Wertentwicklung, Erinnerungen und ein Schutz vor
+doppelten Katalogeintraegen.
+
+### Hinzugefuegt
+
+**Mehrere Sammler**
+- Der Katalog bleibt gemeinsam, Sammlung und Wunschlisten gehoeren je einem
+  Sammler. "Hat er das schon?" beantwortet damit die Frage fuer *ihn*: ein Set,
+  das nur die Schwester besitzt, faellt fuer den Bruder unter "fehlt noch".
+- Umschalter in Katalog und Sammlung, Farbmarkierung je Sammler, Zuordnung im
+  Sammlungseintrag und je Wunschliste.
+- Solange es nur einen Sammler gibt, ist davon nichts zu sehen - die App
+  bleibt genauso einfach wie vorher.
+
+**Preisbeobachtung**
+- Notierte Preise je Set mit Betrag, Zustand, Datum, Quelle und Notiz.
+- Wertentwicklung gegen die UVP, in der Sammlung als Kachel "Aktueller Wert".
+
+**Erinnerungen**
+- E-Mail an den Besitzer, wenn der Termin einer Wunschliste naeher rueckt und
+  noch Wuensche offen sind - standardmaessig 14 Tage vorher, hoechstens einmal
+  pro Woche je Liste.
+- Verwaltungsseite mit Verbindungstest, Testnachricht und sofortiger Pruefung.
+- Ohne SMTP-Konfiguration bleibt die Funktion vollstaendig aus.
+
+**Dublettenpruefung**
+- Vor dem Anlegen eines Sets warnt die App vor gleicher Setnummer beim
+  gleichen Hersteller, sehr aehnlichem Namen und gleicher Nummer bei einem
+  anderen Hersteller - mit Link zum Verdaechtigen und der Moeglichkeit,
+  trotzdem anzulegen.
+
+### Geaendert
+
+- Die Migration legt einen Sammler "Sammlung" an und ordnet ihm alle
+  vorhandenen Sammlungseintraege und Wunschlisten zu. Umbenennen unter
+  Verwaltung -> Sammler.
+- Der Smoke-Test laeuft gegen das Docker-Image statt gegen den Dev-Server.
+
+### Nicht umgesetzt
+
+- Der BrickLink-Preisfuehrer war im Plan als optional vermerkt und wurde
+  bewusst weggelassen: OAuth1 mit einer pro Nutzer registrierten Anwendung ist
+  viel Apparat fuer eine Zahl, die sich in zehn Sekunden eintippen laesst. Das
+  Feld "Wo" nimmt jede Quelle auf, die Datenstruktur bleibt offen.
+
 ## [0.2.0] - 2026-09-07
 
 Phase 2: die Handgriffe, die den Alltag schneller machen.
@@ -147,6 +194,7 @@ Erste lauffaehige Fassung: Phase 1 vollstaendig, im Docker-Stack verifiziert.
 - Unter Windows scheitert `pnpm build` an fehlenden Symlink-Rechten. Der
   Docker-Build unter Linux ist davon nicht betroffen.
 
-[Unreleased]: https://git.wilde-server.de/florian.wilde/bricktrack/compare/v0.2.0...HEAD
+[Unreleased]: https://git.wilde-server.de/florian.wilde/bricktrack/compare/v0.3.0...HEAD
+[0.3.0]: https://git.wilde-server.de/florian.wilde/bricktrack/releases/tag/v0.3.0
 [0.2.0]: https://git.wilde-server.de/florian.wilde/bricktrack/releases/tag/v0.2.0
 [0.1.0]: https://git.wilde-server.de/florian.wilde/bricktrack/releases/tag/v0.1.0

CLAUDE.md

@@ -57,6 +57,10 @@ Bild-URLs, die der Nutzer selbst hinterlegt hat.
 | `src/lib/rebrickable.ts` | Lego-Import, ausschliesslich serverseitig |
 | `src/lib/set-number.ts`, `src/lib/ean.ts` | Setnummern und Barcodes (rein, testbar) |
 | `src/lib/uploads.ts` | Datei-Uploads, Magic Bytes, Thumbnails |
+| `src/lib/similarity.ts` | Namensvergleich fuer die Dublettenpruefung (rein) |
+| `src/lib/prices.ts` | Wertentwicklung aus notierten Preisen (rein) |
+| `src/lib/reminders.ts` | Regeln, wann eine Erinnerung faellig ist (rein) |
+| `src/lib/reminder-job.ts`, `src/lib/mailer.ts` | Versand und Zeitplan |
 | `src/lib/export.ts` | Export und Import des gesamten Bestands |
 | `src/lib/money.ts`, `src/lib/format.ts` | Cent-Umrechnung, dd.MM.yyyy |
 
@@ -114,8 +118,16 @@ Diese Bedingung steht an genau einer Stelle: `src/lib/ownership.ts`.
 
 ### Besitz
 
+Mehrere **Sammler** teilen sich den Katalog, nicht den Besitz: `collector`
+haelt Name und Farbe, `collection_item.collector_id` und
+`wishlist.collector_id` ordnen zu. Solange nur ein Sammler existiert, blendet
+die Oberflaeche das Thema vollstaendig aus - Umschalter, Abfragen und Badges
+erscheinen erst ab dem zweiten.
+
 | Tabelle | Zweck | Wichtige Felder |
 |---|---|---|
+| `collector` | ein Kind | `name`, `color`, `birthday`, `sort_order` |
+| `price_point` | beobachteter Preis je Set | `price_cents`, `condition`, `observed_at`, `source` |
 | `collection_item` | ein besessenes Exemplar | `status` = `owned` / `built` / `disassembled` / `lent_out` / `sold`, `completeness`, `condition`, `location_id`, `acquired_*`, `gifted_by` |
 | `location` | Aufbewahrungsort, hierarchisch | `parent_location_id` |
 | `missing_part` | Fehlteile je Exemplar | `part_number`, `color_name`, `quantity`, `resolved` |
@@ -190,7 +202,7 @@ Session.
 - **Phase 2 (Komfort)** - Rebrickable-Import, Barcode-Scanner, Fehlteile,
   Einladungen, Export/Import, PWA. *Fertig in 0.2.0.*
 - **Phase 3 (Nice to have)** - mehrere Sammler, Preisbeobachtung,
-  E-Mail-Erinnerungen, Dublettenpruefung.
+  E-Mail-Erinnerungen, Dublettenpruefung. *Fertig in 0.3.0.*
 
 Details und Stand: `docs/ROADMAP.md`. Zeitaufwaende: `docs/DEVLOG.md`.
 

README.md

@@ -29,6 +29,9 @@ du per Link mit Familie und Freunden teilst. Die reservieren dort ihr Geschenk
 | **Fotos** | Eigene Bilder je Set – direkt aus der Handykamera |
 | **Wunschlisten** | Mehrfachauswahl aus den fehlenden Sets, Priorität, Reihenfolge, Termin |
 | **Teilen** | Öffentlicher Link ohne Anmeldung, Reservierung mit Namen, Storno-Link, Überraschungsmodus |
+| **Mehrere Kinder** | Gemeinsamer Katalog, getrennte Sammlungen und Wunschlisten – sichtbar erst ab dem zweiten Sammler |
+| **Preise** | Notierte Preise je Set, Wertentwicklung gegen die UVP |
+| **Erinnerungen** | E-Mail, wenn ein Termin näher rückt und noch Wünsche offen sind (SMTP optional) |
 | **Anmeldung** | E-Mail und Passwort oder Passkey (WebAuthn), mehrere Geräte je Konto |
 
 Mobil zuerst gebaut: Die App wird im Laden und im Kinderzimmer benutzt, nicht
@@ -81,7 +84,9 @@ Alle Werte kommen aus `.env` (Vorlage: `.env.example`).
 | `TZ` | nein | `Europe/Berlin` | Zeitzone des Containers. |
 | `BIND_ADDRESS` | nein | `127.0.0.1` | Auf welcher Host-Adresse der Container lauscht. `0.0.0.0`, wenn der Proxy auf einem anderen Host läuft. |
 | `HOST_PORT` | nein | `3000` | Port auf dem Host, falls 3000 belegt ist. |
-| `REBRICKABLE_API_KEY` | nein | – | Ab Version 0.2.0: Lego-Import. Ohne Key läuft alles manuell. |
+| `REBRICKABLE_API_KEY` | nein | – | Lego-Import. Ohne Key läuft alles manuell. |
+| `SMTP_HOST`, `SMTP_PORT`, `SMTP_USER`, `SMTP_PASSWORD`, `SMTP_FROM` | nein | – | Mailversand für Wunschlisten-Erinnerungen. Ohne `SMTP_HOST` und `SMTP_FROM` ist die Funktion aus. |
+| `REMINDER_DAYS_BEFORE` | nein | `14` | Wie viele Tage vor dem Termin erinnert wird. |
 
 ### Reverse Proxy
 
@@ -208,6 +213,10 @@ Ein verkauftes Exemplar zählt also nicht mehr als Besitz – das Set taucht
 wieder unter „fehlt noch" auf und darf zurück auf eine Wunschliste. Diese
 Regel steht an genau einer Stelle im Code: `src/lib/ownership.ts`.
 
+Gibt es mehrere **Sammler**, bekommt die Frage ein „für wen": Der Katalog ist
+gemeinsam, der Besitz nicht. Ein Set, das nur das Geschwisterkind hat, fehlt
+dem anderen weiterhin.
+
 Das vollständige Modell inklusive aller Tabellen: [CLAUDE.md](CLAUDE.md#datenmodell).
 
 ## Sicherheit

docs/ANLEITUNG.md

@@ -27,7 +27,11 @@ Kinderzimmer, nicht für den Schreibtisch.
 13. [Noch ein Konto für die Familie](#13-einladungen)
 14. [Daten sichern, umziehen, auswerten](#14-daten)
 15. [Auf den Startbildschirm legen](#15-startbildschirm)
-16. [Antworten auf die zwei wichtigen Fragen](#16-die-zwei-fragen)
+16. [Zwei Kinder, ein Katalog](#16-mehrere-sammler)
+17. [Was ein Set heute wert ist](#17-preise)
+18. [Erinnerung vor dem Termin](#18-erinnerungen)
+19. [Schutz vor doppelten Einträgen](#19-dubletten)
+20. [Antworten auf die zwei wichtigen Fragen](#20-die-zwei-fragen)
 
 ---
 
@@ -419,7 +423,115 @@ den Zwischenspeicher, damit auf einem geteilten Gerät nichts lesbar bleibt.
 
 ---
 
-## 16. Die zwei Fragen
+## 16. Mehrere Sammler
+
+![Sammler verwalten](bilder/21-sammler.png)
+
+Kommt ein zweites Kind dazu, wird aus „hat er das schon?" die Frage „hat
+**er** das schon?". Genau dafür gibt es Sammler.
+
+Der **Katalog bleibt gemeinsam**: Ein Set existiert einmal, unabhängig davon,
+wer es besitzt. **Sammlung und Wunschlisten** gehören dagegen je einem
+Sammler. Ein Set, das nur die Schwester hat, fällt für den Bruder wieder unter
+„fehlt noch" – und darf auf seine Wunschliste.
+
+> **Solange es nur einen Sammler gibt, siehst du davon nichts.** Kein
+> Umschalter, keine Abfrage, keine Farben. Die App bleibt genauso einfach wie
+> vorher. Erst der zweite Sammler schaltet all das frei – und dann willst du
+> es auch.
+
+Anlegen unter **Verwaltung → Sammler**. Jeder bekommt einen Namen und eine
+Farbe zur Unterscheidung.
+
+![Nach Sammler filtern](bilder/22-sammler-filter.png)
+
+Danach steht in Katalog und Sammlung oben ein Umschalter. „Alle zusammen"
+zeigt den Haushalt als Ganzes, ein Name zeigt genau dessen Sicht – inklusive
+der Frage, was **diesem** Kind noch fehlt.
+
+Beim Hinzufügen zur Sammlung fragt die App jetzt, wer das Set bekommt. Und
+beim Anlegen einer Wunschliste, für wen sie ist: Das bestimmt, wessen Sammlung
+als „hat er schon" zählt und wann ein Wunsch automatisch als erfüllt gilt.
+
+> Die Umstellung einer bestehenden Instanz macht nichts kaputt: Beim Update
+> entsteht ein Sammler namens „Sammlung", dem alles Vorhandene gehört.
+> Umbenennen unter **Verwaltung → Sammler**, fertig.
+
+---
+
+## 17. Preise
+
+![Preis und Wertentwicklung](bilder/23-preise.png)
+
+Auf jeder Set-Seite gibt es **„Preis notieren"**: Betrag, Zustand (neu oder
+gebraucht), wann und wo gesehen. Daraus wird eine Reihe – und damit eine
+Antwort auf die eigentlich interessante Frage: Was hat das Set seit dem Kauf
+gemacht?
+
+- **Ursprünglich** ist die UVP des Sets, sonst der älteste notierte Preis.
+- **Aktuell** ist der neueste notierte Preis.
+- **Entwicklung** ist die Differenz in Prozent.
+
+In der Sammlung wird die Kachel „Wert nach UVP" automatisch zu **„Aktueller
+Wert"**, sobald irgendwo ein Preis notiert ist.
+
+> Es wird **kein** Preisdienst abgefragt. Was hier steht, hast du selbst
+> eingetragen – das ist ehrlicher als eine Zahl, deren Herkunft niemand kennt,
+> und es geht nichts nach draußen.
+
+---
+
+## 18. Erinnerungen
+
+![Erinnerungen](bilder/24-erinnerungen.png)
+
+Wenn ein Wunschlisten-Termin näher rückt und **noch Wünsche offen sind**,
+schickt Bricktrack dir eine E-Mail – standardmäßig 14 Tage vorher, höchstens
+einmal pro Woche je Liste. Ist alles reserviert, bleibt es still: eine
+Erinnerung ohne Handlungsbedarf ist nur Lärm.
+
+Dafür braucht es einen SMTP-Zugang in der `.env`:
+
+```bash
+SMTP_HOST=mail.example.de
+SMTP_PORT=587
+SMTP_USER=bricktrack@example.de
+SMTP_PASSWORD=…
+SMTP_FROM=Bricktrack <bricktrack@example.de>
+
+# Optional, Standard ist 14:
+REMINDER_DAYS_BEFORE=14
+```
+
+Unter **Verwaltung → Erinnerungen** kannst du die Verbindung prüfen, dir eine
+Testnachricht schicken und die Prüfung sofort auslösen, statt auf die nächste
+Stunde zu warten. Dort steht auch, welche Listen einen Termin haben und wie
+viel dort noch offen ist.
+
+Ohne SMTP-Zugang ist die Funktion vollständig aus – alles andere funktioniert
+unverändert.
+
+---
+
+## 19. Dubletten
+
+Beim Anlegen eines neuen Sets schaut Bricktrack nach, ob es das schon gibt:
+
+- **gleiche Setnummer beim gleichen Hersteller** – dann ist es dasselbe Set,
+- **sehr ähnlicher Name** – meist ein Tippfehler oder eine andere Schreibweise,
+- **gleiche Nummer bei einem anderen Hersteller** – meist der falsche
+  Hersteller im Formular.
+
+Passt etwas, erscheint ein Hinweis mit Link zu den Verdächtigen. Von dort
+kommst du direkt zum vorhandenen Eintrag – oder legst mit „Trotzdem anlegen"
+weiter an, wenn es wirklich ein anderes Set ist.
+
+Die Erkennung ist bewusst zurückhaltend eingestellt: Tippfehler schlagen an,
+zwei echte Sets desselben Themas nicht.
+
+---
+
+## 20. Die zwei Fragen
 
 Dafür ist die ganze App gebaut:
 
@@ -428,7 +540,8 @@ Dafür ist die ganze App gebaut:
 
 **„Welche Sets hat er noch nicht?"**
 → Katalog, Filter „Fehlt noch". Von dort in zwei Handgriffen auf eine
-Wunschliste und per Link zu Oma.
+Wunschliste und per Link zu Oma. Bei mehreren Kindern beantwortet der
+Umschalter oben die Frage für jedes einzeln.
 
 Im Laden vor dem Regal: Scanner öffnen, Strichcode einlesen. Steht ein grüner
 Haken dran, habt ihr es schon.

docs/DEVLOG.md

@@ -45,6 +45,20 @@ Commit-Spalte verweist auf den Stand am Ende des Schritts.
 
 **Summe Phase 2: 0:55**
 
+## Phase 3 – Nice to have (v0.3.0)
+
+### 07.09.2026
+
+| Von | Bis | Dauer | Schritt | Ergebnis | Commit |
+|---|---|---|---|---|---|
+| 08:35 | 09:00 | 0:25 | Mehrere Sammler | Neue Tabelle, Migration mit Nachziehen der Bestandsdaten, Besitzlogik um eine Dimension erweitert, Umschalter in Katalog und Sammlung, Zuordnung in Sammlungseintrag und Wunschliste | `c23b754` |
+| 09:00 | 09:13 | 0:13 | Dublettenprüfung | Ähnlichkeitsvergleich mit konservativer Schwelle, Warndialog mit Links, E2E-Test | `87131b8` |
+| 09:13 | 09:17 | 0:04 | Preisbeobachtung | Preisreihe je Set, Wertentwicklung gegen die UVP, Kachel „Aktueller Wert" | `91fb66b` |
+| 09:17 | 09:22 | 0:05 | Erinnerungen | SMTP optional, stündliche Prüfung, Sperrfrist je Liste, Verwaltungsseite mit Testfunktionen | `0d08df0` |
+| 09:22 | 09:50 | 0:28 | Verifikation und Dokumentation | Docker-Build, Smoke-Test, Screenshots, Changelog 0.3.0, Anleitung | folgt |
+
+**Summe Phase 3: 1:15**
+
 ---
 
 ## Notizen und Entscheidungen
@@ -120,6 +134,21 @@ Commit-Spalte verweist auf den Stand am Ende des Schritts.
   Konfliktregeln für jede Tabelle und wäre im Ergebnis nicht vorhersagbar.
   Der Import ersetzt deshalb – dafür mit getipptem `ERSETZEN` als Bremse.
 
+### Phase 3
+
+- **Migration mit Bestandsdaten**: Die generierte SQL-Datei wurde von Hand um
+  drei Anweisungen ergänzt, die einen Sammler anlegen und alles Vorhandene
+  zuordnen. Ohne das wären nach dem Update alle Sammlungseinträge ohne
+  Besitzer gewesen.
+- **Instrumentation und native Module**: Der Zeitplan für Erinnerungen liess
+  sich nicht aus Next' `instrumentation.ts` starten – die Datei wird auch für
+  die Edge-Runtime übersetzt, und das native SQLite-Modul bricht dort den
+  Build. Der Zeitplan startet jetzt aus dem Healthcheck heraus, den der
+  Container ohnehin alle 30 Sekunden aufruft.
+- **BrickLink bewusst weggelassen**: OAuth1 mit einer pro Nutzer registrierten
+  Anwendung ist viel Apparat für eine Zahl, die man in zehn Sekunden eintippt.
+  Im Plan war der Punkt als optional vermerkt.
+
 ### Beim Testen gefunden und behoben
 
 - Eine spontan aus dem Katalog angelegte Wunschliste war **nicht teilbar**:
@@ -130,3 +159,8 @@ Commit-Spalte verweist auf den Stand am Ende des Schritts.
   `required` des Eingabefeldes.
 - In der Mehrfachauswahl verdeckte die Aktionsleiste die letzte Kachelreihe;
   das Raster bekommt im Auswahlmodus zusätzliches Polster nach unten.
+- Die Sperrfrist der Erinnerungen rechnete mit umgedrehtem Vorzeichen und
+  hätte jede Erinnerung dauerhaft unterdrückt. Der Test dafür war zuerst da.
+- Der Screenshot-Lauf wählte plötzlich die falschen Kacheln aus: Der neue
+  Sammler-Umschalter benutzt ebenfalls `aria-pressed`. Die Auswahlkacheln
+  tragen jetzt ein eigenes `data-set-card`.

docs/ROADMAP.md

@@ -46,12 +46,25 @@ Laeuft vollstaendig im Docker-Stack.
       Sammlung zusaetzlich als CSV
 - [x] PWA: Manifest, Service Worker, Katalog offline lesbar
 
-## Phase 3 - Nice to have (Ziel: v0.3.0)
+## Phase 3 - Nice to have (v0.3.0, abgeschlossen am 07.09.2026)
 
-- [ ] Mehrere Sammler mit eigener Sammlung und eigenen Wunschlisten,
+- [x] Mehrere Sammler mit eigener Sammlung und eigenen Wunschlisten,
       gemeinsamer Katalog
-- [ ] Preisbeobachtung und Wertentwicklung (manuell gepflegt,
-      optional BrickLink-Preisfuehrer)
-- [ ] E-Mail-Erinnerung (SMTP), wenn ein Wunschlisten-Termin naeher
+- [x] Preisbeobachtung und Wertentwicklung (manuell gepflegt).
+      Der BrickLink-Preisfuehrer war als optional vermerkt und wurde
+      bewusst weggelassen: er verlangt OAuth1 mit einer pro Nutzer
+      registrierten Anwendung - viel Apparat fuer eine Zahl, die sich in
+      zehn Sekunden eintippen laesst. Die Datenstruktur ist offen dafuer.
+- [x] E-Mail-Erinnerung (SMTP), wenn ein Wunschlisten-Termin naeher
       rueckt und Eintraege unreserviert sind
-- [ ] Dublettenpruefung beim Anlegen von Sets
+- [x] Dublettenpruefung beim Anlegen von Sets
+
+## Danach
+
+Phase 1 bis 3 sind umgesetzt. Was noch offen ist, steht hier - ohne Termin
+und ohne Anspruch auf Vollstaendigkeit:
+
+- [ ] BrickLink-Preisfuehrer anbinden, falls der Aufwand sich doch lohnt
+- [ ] Mehrere Fotos je Sammlungseintrag (bisher nur je Set)
+- [ ] Anleitungen im PDF-Viewer durchsuchen
+- [ ] Statistik ueber die Zeit: was kam wann dazu

drizzle/0001_lumpy_bill_hollister.sql

@@ -0,0 +1,28 @@
+CREATE TABLE `collector` (
+	`id` text PRIMARY KEY NOT NULL,
+	`name` text NOT NULL,
+	`color` text DEFAULT 'blue' NOT NULL,
+	`birthday` integer,
+	`notes` text,
+	`sort_order` integer DEFAULT 0 NOT NULL,
+	`created_at` integer NOT NULL,
+	`updated_at` integer NOT NULL
+);
+--> statement-breakpoint
+CREATE INDEX `collector_sort_idx` ON `collector` (`sort_order`,`name`);--> statement-breakpoint
+ALTER TABLE `collection_item` ADD `collector_id` text REFERENCES collector(id);--> statement-breakpoint
+CREATE INDEX `collection_item_collector_idx` ON `collection_item` (`collector_id`);--> statement-breakpoint
+ALTER TABLE `wishlist` ADD `collector_id` text REFERENCES collector(id);--> statement-breakpoint
+-- Von Hand ergaenzt: Bestandsdaten nachziehen.
+-- Vor dieser Migration gab es genau eine Sammlung. Sie bekommt einen Sammler,
+-- damit alles Vorhandene zugeordnet bleibt; umbenennen laesst er sich unter
+-- Verwaltung -> Sammler.
+INSERT INTO `collector` (`id`, `name`, `color`, `sort_order`, `created_at`, `updated_at`)
+SELECT 'c0000000-0000-4000-8000-000000000001', 'Sammlung', 'blue', 0, unixepoch(), unixepoch()
+WHERE NOT EXISTS (SELECT 1 FROM `collector`);--> statement-breakpoint
+UPDATE `collection_item`
+SET `collector_id` = (SELECT `id` FROM `collector` ORDER BY `sort_order`, `name` LIMIT 1)
+WHERE `collector_id` IS NULL;--> statement-breakpoint
+UPDATE `wishlist`
+SET `collector_id` = (SELECT `id` FROM `collector` ORDER BY `sort_order`, `name` LIMIT 1)
+WHERE `collector_id` IS NULL;

drizzle/0002_aspiring_whiplash.sql

@@ -0,0 +1,14 @@
+CREATE TABLE `price_point` (
+	`id` text PRIMARY KEY NOT NULL,
+	`set_id` text NOT NULL,
+	`price_cents` integer NOT NULL,
+	`condition` text DEFAULT 'new' NOT NULL,
+	`source` text,
+	`observed_at` integer NOT NULL,
+	`note` text,
+	`created_at` integer NOT NULL,
+	FOREIGN KEY (`set_id`) REFERENCES `set`(`id`) ON UPDATE no action ON DELETE cascade,
+	CONSTRAINT "price_point_positive" CHECK("price_point"."price_cents" >= 0)
+);
+--> statement-breakpoint
+CREATE INDEX `price_point_set_idx` ON `price_point` (`set_id`,`observed_at`);

drizzle/0003_powerful_sally_floyd.sql

@@ -0,0 +1 @@
+ALTER TABLE `wishlist` ADD `last_reminder_at` integer;

drizzle/meta/_journal.json

@@ -8,6 +8,27 @@
       "when": 1788726503038,
       "tag": "0000_rapid_gargoyle",
       "breakpoints": true
+    },
+    {
+      "idx": 1,
+      "version": "6",
+      "when": 1788763704015,
+      "tag": "0001_lumpy_bill_hollister",
+      "breakpoints": true
+    },
+    {
+      "idx": 2,
+      "version": "6",
+      "when": 1788765229376,
+      "tag": "0002_aspiring_whiplash",
+      "breakpoints": true
+    },
+    {
+      "idx": 3,
+      "version": "6",
+      "when": 1788765478965,
+      "tag": "0003_powerful_sally_floyd",
+      "breakpoints": true
     }
   ]
 }

e2e/screenshots.spec.ts

@@ -66,7 +66,8 @@ test('Screenshots fuer die Anleitung', async ({ page, browser }) => {
 
   await page.getByRole('button', { name: 'Auswählen' }).click();
   await expect(page.getByText('Tippe die Sets an')).toBeVisible();
-  const cards = page.locator('button[aria-pressed]');
+  // data-set-card, not aria-pressed: the collector switcher uses that too.
+  const cards = page.locator('button[data-set-card]');
   await cards.nth(0).click();
   await cards.nth(1).click();
   await expect(page.getByText('2 ausgewählt')).toBeVisible();
@@ -160,4 +161,33 @@ test('Screenshots fuer die Anleitung', async ({ page, browser }) => {
   await visit(page, '/verwaltung/daten');
   await expect(page.getByText('Alles als ZIP')).toBeVisible();
   await shoot(page, '20-daten');
+
+  // --- 16. collectors -------------------------------------------------------
+  await visit(page, '/verwaltung/sammler');
+  await expect(page.getByText('Der Katalog ist gemeinsam')).toBeVisible();
+  await shoot(page, '21-sammler');
+
+  // The switcher only exists because the seed created two collectors.
+  await visit(page, '/katalog?besitz=fehlt');
+  await expect(page.getByRole('button', { name: /Max/ })).toBeVisible();
+  await page.getByRole('button', { name: /Max/ }).click();
+  await expect(page.getByText('Sets, die Max noch nicht hat')).toBeVisible();
+  await shoot(page, '22-sammler-filter');
+
+  // --- 17. prices -----------------------------------------------------------
+  await visit(page, '/katalog?q=60398');
+  await page.getByText('Familienhaus und Elektroauto').first().click();
+  await expect(page.getByText('Preis und Wertentwicklung')).toBeVisible();
+  await page.getByRole('button', { name: 'Preis notieren' }).click();
+  // Role, not label: the label text carries the required marker.
+  await page.getByRole('textbox', { name: 'Preis', exact: true }).fill('79,99');
+  await page.getByLabel('Wo').fill('Amazon');
+  await page.getByRole('button', { name: 'Speichern' }).click();
+  await expect(page.getByText('Amazon')).toBeVisible();
+  await shoot(page, '23-preise');
+
+  // --- 18. reminders --------------------------------------------------------
+  await visit(page, '/verwaltung/erinnerungen');
+  await expect(page.getByText('Erinnerungen').first()).toBeVisible();
+  await shoot(page, '24-erinnerungen');
 });

e2e/smoke.spec.ts

@@ -81,6 +81,30 @@ test('Registrieren, Set anlegen, Wunschliste teilen und reservieren', async ({ p
   await visitorContext.close();
 });
 
+test('Dublettenpruefung warnt vor einem fast gleichen Set', async ({ page }) => {
+  await page.goto('/anmelden');
+  await page.getByLabel('E-Mail').fill('test@bricktrack.local');
+  await page.getByLabel('Passwort').fill('smoketest-passwort');
+  await page.getByRole('button', { name: 'Anmelden', exact: true }).click();
+  await expect(page.getByRole('heading', { name: 'Hallo Florian' })).toBeVisible();
+
+  // Dasselbe Set noch einmal, mit Tippfehler im Namen und anderer Nummer.
+  await page.goto('/katalog/neu');
+  await page.getByLabel('Setnummer').fill('60399');
+  await page
+    .getByRole('textbox', { name: 'Name', exact: true })
+    .fill('Familienhaus und Elektroauo');
+  await page.getByRole('button', { name: 'Set anlegen' }).click();
+
+  await expect(page.getByText('Gibt es das vielleicht schon?')).toBeVisible();
+  await expect(page.getByText('Sehr ähnlicher Name')).toBeVisible();
+
+  // Zurueck ins Formular: nichts wurde angelegt.
+  await page.getByRole('button', { name: 'Zurück zum Formular' }).click();
+  await page.goto('/katalog?q=60399');
+  await expect(page.getByText('0 Sets')).toBeVisible();
+});
+
 test('Einladung: zweiter Elternteil bekommt ein eigenes Konto', async ({ page, browser }) => {
   // The admin from the first test is still the only account, so log in.
   await page.goto('/anmelden');

package.json

@@ -36,6 +36,7 @@
     "lucide-react": "^1.41.0",
     "next": "15.5.25",
     "next-themes": "^0.4.6",
+    "nodemailer": "^10.0.0",
     "pdfjs-dist": "^6.3.289",
     "radix-ui": "^1.6.7",
     "react": "19.1.0",
@@ -52,6 +53,7 @@
     "@tailwindcss/postcss": "^4",
     "@types/better-sqlite3": "^9.6.0",
     "@types/node": "^20",
+    "@types/nodemailer": "^8.0.1",
     "@types/react": "^19",
     "@types/react-dom": "^19",
     "dotenv": "^17.4.2",

pnpm-lock.yaml

@@ -47,6 +47,9 @@ importers:
       next-themes:
         specifier: ^0.4.6
         version: 0.4.6(react-dom@19.1.0(react@19.1.0))(react@19.1.0)
+      nodemailer:
+        specifier: ^10.0.0
+        version: 10.0.0
       pdfjs-dist:
         specifier: ^6.3.289
         version: 6.3.289
@@ -90,6 +93,9 @@ importers:
       '@types/node':
         specifier: ^20
         version: 20.19.43
+      '@types/nodemailer':
+        specifier: ^8.0.1
+        version: 8.0.1
       '@types/react':
         specifier: ^19
         version: 19.2.18
@@ -2262,6 +2268,9 @@ packages:
   '@types/node@20.19.43':
     resolution: {integrity: sha512-6oYBAi5ikg4Pl+kGsoYtawUMBT2zZMCvPNF7pVLnHZfd1zf38DRiWn/gT01RYCdUqkv7Fhr+C9ot4/tb+2sVvA==}
 
+  '@types/nodemailer@8.0.1':
+    resolution: {integrity: sha512-PxpaInm8V1JQDd4j0ds5HfvWQk8JupS1C0Picb96QJsrrRDjBH+DlK7L4ZdNSqNULhiZRQHc40nLVShaGxXAMw==}
+
   '@types/react-dom@19.2.7':
     resolution: {integrity: sha512-I8bPpDLcHBv1qiIiXDCy71Rt8eQDKJP0sMSWJphDdAcdqiJ1sGpZamavoEIRZmYzjia9LuEb2HlYdDpmoENpvQ==}
     peerDependencies:
@@ -4135,6 +4144,10 @@ packages:
     resolution: {integrity: sha512-YHs7BmmcsdAI5Ozuf8JZo6PT0mv2GIWC9vMfvUC3dp65M8hn7Ux8CPL+2oBI7juNuj9d0ndhTcznq2ODBps9cQ==}
     engines: {node: '>=18'}
 
+  nodemailer@10.0.0:
+    resolution: {integrity: sha512-wdv+hXBg0iIPIOf108FaZyTxqjQpCvQeAJt9pHHTooPy/y3vQtI9eiImM9AIVKR3e/0FeMA1oueNfBjFJcaK+Q==}
+    engines: {node: '>=20.0.0'}
+
   npm-run-path@4.0.1:
     resolution: {integrity: sha512-S48WzZW777zhNIrn7gxOlISNAqi9ZC/uQFnRdbeIHhZhCA6UqpkOT8T1G7BvfdgP4Er8gF4sUbaS0i7QvIfCWw==}
     engines: {node: '>=8'}
@@ -6950,6 +6963,10 @@ snapshots:
     dependencies:
       undici-types: 6.21.0
 
+  '@types/nodemailer@8.0.1':
+    dependencies:
+      '@types/node': 20.19.43
+
   '@types/react-dom@19.2.7(@types/react@19.2.18)':
     dependencies:
       '@types/react': 19.2.18
@@ -8805,6 +8822,8 @@ snapshots:
 
   node-releases@2.0.54: {}
 
+  nodemailer@10.0.0: {}
+
   npm-run-path@4.0.1:
     dependencies:
       path-key: 3.1.1

scripts/e2e-prepare.mjs

@@ -17,6 +17,13 @@ fs.mkdirSync(path.join(dataDir, 'db'), { recursive: true });
 fs.mkdirSync(path.join(dataDir, 'files'), { recursive: true });
 console.log(`[e2e] ${dataDir} zurueckgesetzt.`);
 
+// A container left behind by an aborted run would hold the port.
+try {
+  execFileSync('docker', ['rm', '-f', 'bricktrack-e2e'], { stdio: 'ignore' });
+} catch {
+  // Nothing to remove - the normal case.
+}
+
 console.log('[e2e] Image wird gebaut (bricktrack:e2e) …');
 execFileSync('docker', ['build', '-t', 'bricktrack:e2e', '.'], { stdio: 'inherit' });
 console.log('[e2e] Image ist bereit.');

scripts/screenshots-prepare.mjs

@@ -16,6 +16,13 @@ fs.mkdirSync(path.join(dataDir, 'db'), { recursive: true });
 fs.mkdirSync(path.join(dataDir, 'files'), { recursive: true });
 console.log(`[screenshots] ${dataDir} zurueckgesetzt.`);
 
+// A container left behind by an aborted run would hold the port.
+try {
+  execFileSync('docker', ['rm', '-f', 'bricktrack-shots'], { stdio: 'ignore' });
+} catch {
+  // Nothing to remove - the normal case.
+}
+
 console.log('[screenshots] Image wird gebaut (bricktrack:shots) …');
 execFileSync('docker', ['build', '-t', 'bricktrack:shots', '.'], { stdio: 'inherit' });
 console.log('[screenshots] Image ist bereit.');

scripts/seed.ts

@@ -33,11 +33,12 @@ type SeedSet = {
   minifigCount: number | null;
   retailPriceCents: number;
   ageRange: string;
-  /** Copies owned - 0 means the set is only in the catalog. */
+  /** Copies owned - absent means the set is only in the catalog. */
   owned?: {
     status: 'owned' | 'built' | 'disassembled' | 'lent_out' | 'sold';
     completeness: 'complete' | 'missing_parts' | 'unknown';
     location: string;
+    collector: string;
     giftedBy?: string;
   };
 };
@@ -59,6 +60,13 @@ const THEMES: Array<{ manufacturer: string; name: string }> = [
 
 const LOCATIONS = ['Regal Kinderzimmer', 'Kiste Keller 3', 'Vitrine Wohnzimmer'];
 
+// Two collectors, so the shared catalog and the separate collections are
+// visible right away. With only one, the whole concept stays hidden in the UI.
+const COLLECTORS = [
+  { name: 'Max', color: 'blue' as const },
+  { name: 'Mia', color: 'rose' as const },
+];
+
 const SETS: SeedSet[] = [
   {
     manufacturer: 'Lego',
@@ -70,7 +78,12 @@ const SETS: SeedSet[] = [
     minifigCount: 4,
     retailPriceCents: 4999,
     ageRange: '6-12',
-    owned: { status: 'built', completeness: 'complete', location: 'Regal Kinderzimmer' },
+    owned: {
+      status: 'built',
+      completeness: 'complete',
+      location: 'Regal Kinderzimmer',
+      collector: 'Max',
+    },
   },
   {
     manufacturer: 'Lego',
@@ -86,6 +99,7 @@ const SETS: SeedSet[] = [
       status: 'owned',
       completeness: 'missing_parts',
       location: 'Kiste Keller 3',
+      collector: 'Max',
       giftedBy: 'Oma Helga',
     },
   },
@@ -99,7 +113,12 @@ const SETS: SeedSet[] = [
     minifigCount: null,
     retailPriceCents: 999,
     ageRange: '7-14',
-    owned: { status: 'disassembled', completeness: 'unknown', location: 'Kiste Keller 3' },
+    owned: {
+      status: 'disassembled',
+      completeness: 'unknown',
+      location: 'Kiste Keller 3',
+      collector: 'Mia',
+    },
   },
   {
     manufacturer: 'Lego',
@@ -144,7 +163,12 @@ const SETS: SeedSet[] = [
     minifigCount: 5,
     retailPriceCents: 12999,
     ageRange: '4-10',
-    owned: { status: 'built', completeness: 'complete', location: 'Regal Kinderzimmer' },
+    owned: {
+      status: 'built',
+      completeness: 'complete',
+      location: 'Regal Kinderzimmer',
+      collector: 'Mia',
+    },
   },
   {
     manufacturer: 'Playmobil',
@@ -241,6 +265,59 @@ function seedThemes(manufacturers: Map<string, string>) {
   return byKey;
 }
 
+function seedCollectors() {
+  const byName = new Map<string, string>();
+
+  COLLECTORS.forEach((entry, index) => {
+    const all = db
+      .select({ id: schema.collector.id, name: schema.collector.name })
+      .from(schema.collector)
+      .all();
+
+    const existing = all.find((row) => row.name === entry.name);
+    if (existing) {
+      byName.set(entry.name, existing.id);
+      return;
+    }
+
+    // A fresh install already has the collector the migration created. Rather
+    // than adding a third one next to it, the seed takes it over.
+    const untouchedDefault = all.find(
+      (row) =>
+        row.name === 'Sammlung' &&
+        !db
+          .select({ id: schema.collectionItem.id })
+          .from(schema.collectionItem)
+          .where(eq(schema.collectionItem.collectorId, row.id))
+          .get(),
+    );
+
+    if (untouchedDefault) {
+      db.update(schema.collector)
+        .set({ name: entry.name, color: entry.color, sortOrder: index, updatedAt: now })
+        .where(eq(schema.collector.id, untouchedDefault.id))
+        .run();
+      byName.set(entry.name, untouchedDefault.id);
+      return;
+    }
+
+    const newId = id();
+    db.insert(schema.collector)
+      .values({
+        id: newId,
+        name: entry.name,
+        color: entry.color,
+        sortOrder: index,
+        createdAt: now,
+        updatedAt: now,
+      })
+      .run();
+    byName.set(entry.name, newId);
+  });
+
+  return byName;
+}
+
 function seedLocations() {
   const byName = new Map<string, string>();
 
@@ -270,6 +347,7 @@ function seedSets(
   manufacturers: Map<string, string>,
   themes: Map<string, string>,
   locations: Map<string, string>,
+  collectors: Map<string, string>,
 ) {
   const setIds = new Map<string, string>();
 
@@ -317,6 +395,7 @@ function seedSets(
           completeness: entry.owned.completeness,
           condition: 'good',
           locationId: locations.get(entry.owned.location) ?? null,
+          collectorId: collectors.get(entry.owned.collector) ?? null,
           acquiredAt: new Date(entry.year, 11, 24),
           acquiredPriceCents: entry.retailPriceCents,
           giftedBy: entry.owned.giftedBy ?? null,
@@ -330,7 +409,7 @@ function seedSets(
   return setIds;
 }
 
-function seedWishlist(setIds: Map<string, string>) {
+function seedWishlist(setIds: Map<string, string>, collectors: Map<string, string>) {
   const owner = db.select({ id: schema.user.id }).from(schema.user).get();
   if (!owner) {
     console.log('[seed] Kein Nutzer vorhanden - die Beispiel-Wunschliste wird uebersprungen.');
@@ -353,6 +432,7 @@ function seedWishlist(setIds: Map<string, string>) {
     .values({
       id: wishlistId,
       ownerUserId: owner.id,
+      collectorId: collectors.get('Max') ?? null,
       title: 'Weihnachten 2026',
       occasion: 'christmas',
       eventDate: new Date(2026, 11, 24),
@@ -389,10 +469,12 @@ console.log('[seed] Beispieldaten werden eingespielt …');
 const manufacturers = seedManufacturers();
 const themes = seedThemes(manufacturers);
 const locations = seedLocations();
-const setIds = seedSets(manufacturers, themes, locations);
-seedWishlist(setIds);
+const collectors = seedCollectors();
+const setIds = seedSets(manufacturers, themes, locations, collectors);
+seedWishlist(setIds, collectors);
 
 console.log(
-  `[seed] Fertig: ${manufacturers.size} Hersteller, ${themes.size} Themen, ${setIds.size} Sets.`,
+  `[seed] Fertig: ${collectors.size} Sammler, ${manufacturers.size} Hersteller, ` +
+    `${themes.size} Themen, ${setIds.size} Sets.`,
 );
 sqlite.close();

src/app/(app)/katalog/[id]/page.tsx

@@ -4,6 +4,7 @@ import { notFound } from 'next/navigation';
 import { Check, ExternalLink, Gift, ImageOff, Pencil } from 'lucide-react';
 import { InstructionsSection } from '@/components/katalog/instructions-section';
 import { PhotosSection } from '@/components/katalog/photos-section';
+import { PriceSection } from '@/components/katalog/price-section';
 import { SetActions } from '@/components/katalog/set-actions';
 import { CollectionItemsSection } from '@/components/sammlung/collection-items-section';
 import { Badge } from '@/components/ui/badge';
@@ -17,25 +18,37 @@ import {
   listCollectionItemsForSet,
   listInstructionsForSet,
   listPhotosForSet,
+  listPricePoints,
 } from '@/lib/queries/catalog';
 import { listMissingParts } from '@/lib/queries/collection';
+import { listCollectors, resolveCollectorId } from '@/lib/queries/collectors';
 import { listLocations } from '@/lib/queries/master-data';
 import { listWishlistsForSet, listWishlistTargets } from '@/lib/queries/wishlists';
 import { requireUser } from '@/lib/session';
 
-type Props = { params: Promise<{ id: string }> };
+type Props = {
+  params: Promise<{ id: string }>;
+  searchParams: Promise<Record<string, string | string[] | undefined>>;
+};
 
-export async function generateMetadata({ params }: Props): Promise<Metadata> {
+export async function generateMetadata({ params }: Pick<Props, 'params'>): Promise<Metadata> {
   const { id } = await params;
   const set = getSetById(id);
   return { title: set ? `${set.setNumber} · ${set.name}` : 'Set' };
 }
 
-export default async function SetDetailPage({ params }: Props) {
+export default async function SetDetailPage({ params, searchParams }: Props) {
   await requireUser();
   const { id } = await params;
+  const query = await searchParams;
 
-  const set = getSetById(id);
+  // Keeps the "vorhanden / fehlt" badge in step with the collector the user
+  // was looking at in the catalog.
+  const rawCollector = Array.isArray(query.sammler) ? query.sammler[0] : query.sammler;
+  const collectorId = resolveCollectorId(rawCollector);
+  const collectors = listCollectors();
+
+  const set = getSetById(id, collectorId);
   if (!set) notFound();
 
   const image = setImageSrc(set);
@@ -43,11 +56,16 @@ export default async function SetDetailPage({ params }: Props) {
   const locations = listLocations().map((row) => ({ id: row.id, name: row.name }));
   const locationNames = new Map(locations.map((row) => [row.id, row.name]));
 
+  const collectorsById = new Map(collectors.map((row) => [row.id, row]));
   const collectionItems = listCollectionItemsForSet(set.id).map((item) => ({
     ...item,
     locationName: item.locationId ? (locationNames.get(item.locationId) ?? null) : null,
     setName: `${set.setNumber} · ${set.name}`,
     missingParts: listMissingParts(item.id),
+    collectorName: item.collectorId ? (collectorsById.get(item.collectorId)?.name ?? null) : null,
+    collectorColor: item.collectorId
+      ? (collectorsById.get(item.collectorId)?.color ?? null)
+      : null,
   }));
 
   const facts: Array<[string, string]> = [
@@ -113,6 +131,7 @@ export default async function SetDetailPage({ params }: Props) {
             setName={`${set.setNumber} · ${set.name}`}
             owned={owned}
             wishlists={listWishlistTargets()}
+            collectors={collectors.map((row) => ({ id: row.id, name: row.name }))}
           />
 
           <dl className="grid grid-cols-2 gap-x-4 gap-y-2 text-sm sm:grid-cols-3">
@@ -144,7 +163,24 @@ export default async function SetDetailPage({ params }: Props) {
           <CardTitle>In der Sammlung</CardTitle>
         </CardHeader>
         <CardContent>
-          <CollectionItemsSection items={collectionItems} locations={locations} />
+          <CollectionItemsSection
+            items={collectionItems}
+            locations={locations}
+            collectors={collectors.map((row) => ({ id: row.id, name: row.name }))}
+          />
+        </CardContent>
+      </Card>
+
+      <Card>
+        <CardHeader>
+          <CardTitle>Preis und Wertentwicklung</CardTitle>
+        </CardHeader>
+        <CardContent>
+          <PriceSection
+            setId={set.id}
+            prices={listPricePoints(set.id)}
+            retailPriceCents={set.retailPriceCents}
+          />
         </CardContent>
       </Card>
 

src/app/(app)/katalog/duplicate-actions.ts

@@ -0,0 +1,100 @@
+'use server';
+
+import { and, eq, ne } from 'drizzle-orm';
+import { db } from '@/db';
+import { manufacturer, set } from '@/db/schema';
+import { actionData, type ActionResult } from '@/lib/action-result';
+import { requireUser } from '@/lib/session';
+import { isSimilarName } from '@/lib/similarity';
+
+export type DuplicateCandidate = {
+  id: string;
+  setNumber: string;
+  name: string;
+  manufacturerName: string;
+  /** Why we are showing it. */
+  reason: 'same-number' | 'similar-name' | 'number-elsewhere';
+};
+
+/**
+ * Looks for sets that the one being created might be a duplicate of.
+ *
+ * Three cases, in descending order of certainty:
+ *  - the same number at the same manufacturer (that is a real duplicate and is
+ *    rejected on save anyway),
+ *  - a suspiciously similar name at the same manufacturer,
+ *  - the same number at a different manufacturer, which usually means the
+ *    wrong manufacturer was selected.
+ */
+export async function findDuplicateCandidates(input: {
+  manufacturerId: string;
+  setNumber: string;
+  name: string;
+  excludeSetId?: string;
+}): Promise<ActionResult<{ candidates: DuplicateCandidate[] }>> {
+  await requireUser();
+
+  const setNumber = input.setNumber?.trim() ?? '';
+  const name = input.name?.trim() ?? '';
+  if (!input.manufacturerId || (setNumber === '' && name === '')) {
+    return actionData({ candidates: [] });
+  }
+
+  const rows = db
+    .select({
+      id: set.id,
+      setNumber: set.setNumber,
+      name: set.name,
+      manufacturerId: set.manufacturerId,
+      manufacturerName: manufacturer.name,
+    })
+    .from(set)
+    .innerJoin(manufacturer, eq(manufacturer.id, set.manufacturerId))
+    .where(input.excludeSetId ? ne(set.id, input.excludeSetId) : undefined)
+    .all();
+
+  const candidates: DuplicateCandidate[] = [];
+
+  for (const row of rows) {
+    const sameManufacturer = row.manufacturerId === input.manufacturerId;
+    const sameNumber = setNumber !== '' && row.setNumber.toLowerCase() === setNumber.toLowerCase();
+
+    if (sameManufacturer && sameNumber) {
+      candidates.push({ ...row, reason: 'same-number' });
+      continue;
+    }
+    if (sameManufacturer && name !== '' && isSimilarName(row.name, name)) {
+      candidates.push({ ...row, reason: 'similar-name' });
+      continue;
+    }
+    if (!sameManufacturer && sameNumber) {
+      candidates.push({ ...row, reason: 'number-elsewhere' });
+    }
+  }
+
+  // Certain matches first, and never more than a handful.
+  const order: Record<DuplicateCandidate['reason'], number> = {
+    'same-number': 0,
+    'similar-name': 1,
+    'number-elsewhere': 2,
+  };
+  candidates.sort((a, b) => order[a.reason] - order[b.reason]);
+
+  return actionData({ candidates: candidates.slice(0, 5) });
+}
+
+/** Used by the import to point at an existing entry instead of failing blindly. */
+export async function findSetByNumber(
+  manufacturerId: string,
+  setNumber: string,
+): Promise<ActionResult<{ id: string } | null>> {
+  await requireUser();
+
+  const row = db
+    .select({ id: set.id })
+    .from(set)
+    .where(and(eq(set.manufacturerId, manufacturerId), eq(set.setNumber, setNumber)))
+    .get();
+
+  return actionData(row ?? null);
+}

src/app/(app)/katalog/page.tsx

@@ -1,6 +1,7 @@
 import type { Metadata } from 'next';
 import Link from 'next/link';
 import { Plus } from 'lucide-react';
+import { CollectorFilter } from '@/components/layout/collector-filter';
 import { BarcodeScannerButton } from '@/components/katalog/barcode-scanner';
 import { CatalogFilters } from '@/components/katalog/catalog-filters';
 import { CatalogGrid } from '@/components/katalog/catalog-grid';
@@ -9,6 +10,7 @@ import { Button } from '@/components/ui/button';
 import { pluralize } from '@/lib/format';
 import { OWNERSHIP_FILTER_LABELS, parseOwnershipFilter } from '@/lib/ownership';
 import { CATALOG_PAGE_SIZE, listSets, listSetYears } from '@/lib/queries/catalog';
+import { listCollectors, resolveCollectorId } from '@/lib/queries/collectors';
 import { listManufacturers, listThemes } from '@/lib/queries/master-data';
 import { listWishlistTargets } from '@/lib/queries/wishlists';
 import { requireUser } from '@/lib/session';
@@ -27,6 +29,9 @@ export default async function KatalogPage({ searchParams }: { searchParams: Sear
   const params = await searchParams;
 
   const ownership = parseOwnershipFilter(single(params.besitz));
+  const collectors = listCollectors();
+  const collectorId = resolveCollectorId(single(params.sammler));
+  const activeCollector = collectors.find((row) => row.id === collectorId) ?? null;
   const yearParam = single(params.jahr);
   const page = Number(single(params.seite) ?? '1') || 1;
 
@@ -36,6 +41,7 @@ export default async function KatalogPage({ searchParams }: { searchParams: Sear
     themeId: single(params.thema),
     year: yearParam ? Number(yearParam) : undefined,
     ownership,
+    collectorId,
     page,
   };
 
@@ -57,7 +63,9 @@ export default async function KatalogPage({ searchParams }: { searchParams: Sear
           </h1>
           <p className="text-sm text-muted-foreground">
             {ownership === 'fehlt'
-              ? 'Sets, die noch nicht in der Sammlung sind.'
+              ? activeCollector
+                ? `Sets, die ${activeCollector.name} noch nicht hat.`
+                : 'Sets, die noch nicht in der Sammlung sind.'
               : 'Alle bekannten Sets – unabhängig davon, ob sie schon da sind.'}
           </p>
         </div>
@@ -72,6 +80,11 @@ export default async function KatalogPage({ searchParams }: { searchParams: Sear
         </div>
       </div>
 
+      <CollectorFilter
+        collectors={collectors.map((row) => ({ id: row.id, name: row.name, color: row.color }))}
+        allLabel="Alle zusammen"
+      />
+
       <CatalogFilters options={{ manufacturers, themes, years: listSetYears() }} />
 
       <p className="text-sm text-muted-foreground">
@@ -79,7 +92,7 @@ export default async function KatalogPage({ searchParams }: { searchParams: Sear
         {ownership !== 'alle' ? ` · ${OWNERSHIP_FILTER_LABELS[ownership]}` : ''}
       </p>
 
-      <CatalogGrid sets={rows} wishlists={wishlists} />
+      <CatalogGrid sets={rows} wishlists={wishlists} collectorId={collectorId} />
 
       <Pagination page={page} total={total} pageSize={CATALOG_PAGE_SIZE} />
     </div>

src/app/(app)/katalog/price-actions.ts

@@ -0,0 +1,61 @@
+'use server';
+
+import { revalidatePath } from 'next/cache';
+import { eq } from 'drizzle-orm';
+import { z } from 'zod';
+import { db } from '@/db';
+import { pricePoint } from '@/db/schema';
+import { actionError, actionOk, parseForm, type ActionResult } from '@/lib/action-result';
+import { requireUser } from '@/lib/session';
+import { optionalDate, optionalText, optionalPriceCents } from '@/lib/validation';
+
+const schema = z.object({
+  priceCents: optionalPriceCents,
+  condition: z.enum(['new', 'used']).default('new'),
+  source: optionalText(80),
+  observedAt: optionalDate,
+  note: optionalText(200),
+});
+
+export async function addPricePoint(setId: string, input: unknown): Promise<ActionResult> {
+  await requireUser();
+
+  const parsed = parseForm(schema, input);
+  if (!parsed.ok) return parsed;
+  if (parsed.data.priceCents === null) return actionError('Bitte gib einen Preis an.');
+
+  db.insert(pricePoint)
+    .values({
+      id: crypto.randomUUID(),
+      setId,
+      priceCents: parsed.data.priceCents,
+      condition: parsed.data.condition,
+      source: parsed.data.source,
+      // No date given means "seen today".
+      observedAt: parsed.data.observedAt ?? new Date(),
+      note: parsed.data.note,
+      createdAt: new Date(),
+    })
+    .run();
+
+  revalidatePath(`/katalog/${setId}`);
+  revalidatePath('/sammlung');
+  return actionOk();
+}
+
+export async function deletePricePoint(id: string): Promise<ActionResult> {
+  await requireUser();
+
+  const existing = db
+    .select({ setId: pricePoint.setId })
+    .from(pricePoint)
+    .where(eq(pricePoint.id, id))
+    .get();
+  if (!existing) return actionOk();
+
+  db.delete(pricePoint).where(eq(pricePoint.id, id)).run();
+
+  revalidatePath(`/katalog/${existing.setId}`);
+  revalidatePath('/sammlung');
+  return actionOk();
+}

src/app/(app)/layout.tsx

@@ -1,8 +1,13 @@
 import { AppHeader } from '@/components/layout/app-header';
 import { BottomNav } from '@/components/layout/bottom-nav';
+import { ensureReminderScheduler } from '@/lib/reminder-job';
 import { requireUser } from '@/lib/session';
 
 export default async function AppLayout({ children }: { children: React.ReactNode }) {
+  // Second entry point besides the healthcheck, in case someone turns that
+  // off. The call is idempotent.
+  ensureReminderScheduler();
+
   const user = await requireUser();
 
   return (

src/app/(app)/sammlung/actions.ts

@@ -11,6 +11,7 @@ import {
   parseForm,
   type ActionResult,
 } from '@/lib/action-result';
+import { defaultCollectorId } from '@/lib/queries/collectors';
 import { reconcileFulfilledWishlistItems } from '@/lib/queries/wishlists';
 import { requireUser } from '@/lib/session';
 import { collectionItemSchema, missingPartSchema } from '@/lib/validation';
@@ -32,17 +33,24 @@ function revalidateCollection(setId?: string) {
  * Quick add from the set detail page: one tap, sensible defaults, details can
  * be filled in later.
  */
-export async function addSetToCollection(setId: string): Promise<ActionResult<{ id: string }>> {
+export async function addSetToCollection(
+  setId: string,
+  collectorId?: string,
+): Promise<ActionResult<{ id: string }>> {
   await requireUser();
 
   const exists = db.select({ id: set.id }).from(set).where(eq(set.id, setId)).get();
   if (!exists) return actionError('Das Set gibt es nicht mehr.');
 
+  // With a single collector nobody is asked - the copy simply belongs to them.
+  const owner = collectorId ?? defaultCollectorId();
+
   const id = crypto.randomUUID();
   db.insert(collectionItem)
     .values({
       id,
       setId,
+      collectorId: owner,
       status: 'owned',
       completeness: 'unknown',
       createdAt: now(),
@@ -68,6 +76,7 @@ export async function updateCollectionItem(id: string, input: unknown): Promise<
 
   db.update(collectionItem)
     .set({
+      collectorId: parsed.data.collectorId ?? existing.collectorId,
       status: parsed.data.status,
       completeness: parsed.data.completeness,
       condition: parsed.data.condition as Condition | null,

src/app/(app)/sammlung/page.tsx

@@ -1,10 +1,12 @@
 import type { Metadata } from 'next';
 import Link from 'next/link';
 import { Boxes, Euro, ImageOff, Layers, PackageSearch } from 'lucide-react';
+import { CollectorFilter } from '@/components/layout/collector-filter';
 import { CollectionFilters } from '@/components/sammlung/collection-filters';
 import { Badge } from '@/components/ui/badge';
 import { Card, CardContent } from '@/components/ui/card';
 import { formatDate, formatNumber, pluralize } from '@/lib/format';
+import { collectorBadgeClass } from '@/lib/collector-colors';
 import { setImageSrc } from '@/lib/images';
 import { completenessLabel, statusLabel } from '@/lib/labels';
 import { formatEuro } from '@/lib/money';
@@ -15,6 +17,7 @@ import {
   listCollectionItems,
   type CollectionFilters as Filters,
 } from '@/lib/queries/collection';
+import { listCollectors, resolveCollectorId } from '@/lib/queries/collectors';
 import { listLocations, listManufacturers } from '@/lib/queries/master-data';
 import { requireUser } from '@/lib/session';
 import type { CollectionStatus, Completeness } from '@/db/types';
@@ -32,23 +35,33 @@ export default async function SammlungPage({ searchParams }: { searchParams: Sea
   await requireUser();
   const params = await searchParams;
 
+  const collectors = listCollectors();
+  const collectorId = resolveCollectorId(single(params.sammler));
+  const activeCollector = collectors.find((row) => row.id === collectorId) ?? null;
+
   const filters: Filters = {
     q: single(params.q),
     status: single(params.status) as CollectionStatus | undefined,
     completeness: single(params.zustand) as Completeness | undefined,
     locationId: single(params.standort),
     manufacturerId: single(params.hersteller),
+    collectorId,
   };
 
   const items = listCollectionItems(filters);
   const openParts = countOpenMissingParts(items.map((item) => item.id));
-  const stats = getCollectionStats();
-  const missing = countMissingSets();
+  const stats = getCollectionStats(collectorId);
+  const missing = countMissingSets(collectorId);
 
   const tiles = [
     { icon: Boxes, label: 'Sets', value: formatNumber(stats.setCount) },
     { icon: Layers, label: 'Teile gesamt', value: formatNumber(stats.pieceCount) },
-    { icon: Euro, label: 'Wert nach UVP', value: formatEuro(stats.retailValueCents) },
+    {
+      icon: Euro,
+      // Notierte Preise gehen vor, sonst die UVP.
+      label: stats.currentValueCents === stats.retailValueCents ? 'Wert nach UVP' : 'Aktueller Wert',
+      value: formatEuro(stats.currentValueCents),
+    },
     { icon: PackageSearch, label: 'Fehlt noch', value: formatNumber(missing) },
   ] as const;
 
@@ -56,9 +69,18 @@ export default async function SammlungPage({ searchParams }: { searchParams: Sea
     <div className="space-y-5">
       <div>
         <h1 className="text-2xl font-semibold tracking-tight">Sammlung</h1>
-        <p className="text-sm text-muted-foreground">Alles, was tatsächlich da ist.</p>
+        <p className="text-sm text-muted-foreground">
+          {activeCollector
+            ? `Alles, was ${activeCollector.name} tatsächlich hat.`
+            : 'Alles, was tatsächlich da ist.'}
+        </p>
       </div>
 
+      <CollectorFilter
+        collectors={collectors.map((row) => ({ id: row.id, name: row.name, color: row.color }))}
+        allLabel="Alle zusammen"
+      />
+
       <div className="grid grid-cols-2 gap-3 sm:grid-cols-4">
         {tiles.map((tile) => (
           <Card key={tile.label}>
@@ -134,6 +156,11 @@ export default async function SammlungPage({ searchParams }: { searchParams: Sea
                       {item.completeness !== 'unknown' ? (
                         <Badge variant="secondary">{completenessLabel(item.completeness)}</Badge>
                       ) : null}
+                      {collectors.length > 1 && item.collectorName ? (
+                        <Badge className={collectorBadgeClass(item.collectorColor)}>
+                          {item.collectorName}
+                        </Badge>
+                      ) : null}
                       {openParts.get(item.id) ? (
                         <Badge variant="outline">{openParts.get(item.id)} Fehlteile</Badge>
                       ) : null}

src/app/(app)/verwaltung/erinnerungen/actions.ts

@@ -0,0 +1,51 @@
+'use server';
+
+import { revalidatePath } from 'next/cache';
+import { actionData, actionError, type ActionResult } from '@/lib/action-result';
+import { env } from '@/env';
+import { sendMail, verifyMailConnection } from '@/lib/mailer';
+import { runReminderJob, type ReminderRun } from '@/lib/reminder-job';
+import { requireAdmin } from '@/lib/session';
+
+export async function testMailConnection(): Promise<ActionResult> {
+  await requireAdmin();
+
+  const result = await verifyMailConnection();
+  return result.ok ? { ok: true } : actionError(result.error);
+}
+
+export async function sendTestMail(): Promise<ActionResult> {
+  const admin = await requireAdmin();
+
+  if (!env.isMailConfigured) {
+    return actionError('Es ist kein SMTP-Server konfiguriert.');
+  }
+
+  const result = await sendMail({
+    to: admin.email,
+    subject: 'Bricktrack: Testnachricht',
+    text: [
+      'Das hat geklappt.',
+      '',
+      'Wenn diese Nachricht ankommt, funktionieren auch die Erinnerungen zu',
+      'Wunschlisten-Terminen.',
+      '',
+      env.BASE_URL,
+    ].join('\n'),
+  });
+
+  return result.ok ? { ok: true } : actionError(result.error);
+}
+
+/** Runs the check immediately instead of waiting for the next hour. */
+export async function runRemindersNow(): Promise<ActionResult<ReminderRun>> {
+  await requireAdmin();
+
+  if (!env.isMailConfigured) {
+    return actionError('Es ist kein SMTP-Server konfiguriert.');
+  }
+
+  const run = await runReminderJob();
+  revalidatePath('/verwaltung/erinnerungen');
+  return actionData(run);
+}

src/app/(app)/verwaltung/erinnerungen/page.tsx

@@ -0,0 +1,51 @@
+import type { Metadata } from 'next';
+import { eq, sql } from 'drizzle-orm';
+import { db } from '@/db';
+import { wishlist } from '@/db/schema';
+import { env } from '@/env';
+import {
+  ReminderSettings,
+  type ReminderListRow,
+} from '@/components/verwaltung/reminder-settings';
+import { daysUntil } from '@/lib/reminders';
+import { requireAdmin } from '@/lib/session';
+
+export const metadata: Metadata = { title: 'Erinnerungen' };
+
+export default async function ErinnerungenPage() {
+  const admin = await requireAdmin();
+
+  const openItems = sql<number>`(
+    select count(*) from wishlist_item wi
+    where wi.wishlist_id = ${wishlist.id}
+      and wi.reserved_at is null
+      and wi.fulfilled_at is null
+  )`.mapWith(Number);
+
+  const now = new Date();
+  const lists: ReminderListRow[] = db
+    .select({
+      id: wishlist.id,
+      title: wishlist.title,
+      eventDate: wishlist.eventDate,
+      lastReminderAt: wishlist.lastReminderAt,
+      openItemCount: openItems,
+    })
+    .from(wishlist)
+    .where(eq(wishlist.ownerUserId, admin.id))
+    .all()
+    .filter((row) => row.eventDate !== null)
+    .map((row) => ({
+      ...row,
+      daysLeft: row.eventDate ? daysUntil(row.eventDate, now) : null,
+    }))
+    .sort((a, b) => (a.daysLeft ?? 0) - (b.daysLeft ?? 0));
+
+  return (
+    <ReminderSettings
+      configured={env.isMailConfigured}
+      daysBefore={env.REMINDER_DAYS_BEFORE}
+      lists={lists}
+    />
+  );
+}

src/app/(app)/verwaltung/sammler/actions.ts

@@ -0,0 +1,160 @@
+'use server';
+
+import { revalidatePath } from 'next/cache';
+import { asc, eq, sql } from 'drizzle-orm';
+import { db } from '@/db';
+import { collectionItem, collector, wishlist } from '@/db/schema';
+import { actionError, actionOk, parseForm, type ActionResult } from '@/lib/action-result';
+import { requireUser } from '@/lib/session';
+import { collectorSchema } from '@/lib/validation';
+
+function now() {
+  return new Date();
+}
+
+function revalidateEverything() {
+  // A collector shows up in the catalog, the collection and the wishlists.
+  revalidatePath('/', 'layout');
+}
+
+export async function createCollector(input: unknown): Promise<ActionResult> {
+  await requireUser();
+
+  const parsed = parseForm(collectorSchema, input);
+  if (!parsed.ok) return parsed;
+
+  const [row] = db
+    .select({ next: sql<number>`coalesce(max(${collector.sortOrder}), -1) + 1`.mapWith(Number) })
+    .from(collector)
+    .all();
+
+  db.insert(collector)
+    .values({
+      id: crypto.randomUUID(),
+      name: parsed.data.name,
+      color: parsed.data.color,
+      birthday: parsed.data.birthday,
+      notes: parsed.data.notes,
+      sortOrder: row?.next ?? 0,
+      createdAt: now(),
+      updatedAt: now(),
+    })
+    .run();
+
+  revalidateEverything();
+  return actionOk();
+}
+
+export async function updateCollector(id: string, input: unknown): Promise<ActionResult> {
+  await requireUser();
+
+  const parsed = parseForm(collectorSchema, input);
+  if (!parsed.ok) return parsed;
+
+  db.update(collector)
+    .set({
+      name: parsed.data.name,
+      color: parsed.data.color,
+      birthday: parsed.data.birthday,
+      notes: parsed.data.notes,
+      updatedAt: now(),
+    })
+    .where(eq(collector.id, id))
+    .run();
+
+  revalidateEverything();
+  return actionOk();
+}
+
+/**
+ * Deleting a collector would take their whole collection with it, so it is
+ * only allowed while nothing is attached - and never for the last one.
+ */
+export async function deleteCollector(id: string): Promise<ActionResult> {
+  await requireUser();
+
+  const remaining = db.select({ id: collector.id }).from(collector).all();
+  if (remaining.length <= 1) {
+    return actionError('Der letzte Sammler kann nicht gelöscht werden.');
+  }
+
+  const owned = db
+    .select({ id: collectionItem.id })
+    .from(collectionItem)
+    .where(eq(collectionItem.collectorId, id))
+    .get();
+  if (owned) {
+    return actionError(
+      'Diesem Sammler sind noch Sets zugeordnet. Ordne sie erst jemand anderem zu, dann lässt er sich löschen.',
+    );
+  }
+
+  const lists = db
+    .select({ id: wishlist.id })
+    .from(wishlist)
+    .where(eq(wishlist.collectorId, id))
+    .get();
+  if (lists) {
+    return actionError(
+      'Zu diesem Sammler gibt es noch Wunschlisten. Ordne sie erst um oder lösch sie.',
+    );
+  }
+
+  db.delete(collector).where(eq(collector.id, id)).run();
+
+  revalidateEverything();
+  return actionOk();
+}
+
+/** Moves every owned copy of one collector over to another. */
+export async function reassignCollectionItems(
+  fromCollectorId: string,
+  toCollectorId: string,
+): Promise<ActionResult> {
+  await requireUser();
+
+  if (fromCollectorId === toCollectorId) return actionOk();
+
+  const target = db
+    .select({ id: collector.id })
+    .from(collector)
+    .where(eq(collector.id, toCollectorId))
+    .get();
+  if (!target) return actionError('Diesen Sammler gibt es nicht.');
+
+  db.update(collectionItem)
+    .set({ collectorId: toCollectorId, updatedAt: now() })
+    .where(eq(collectionItem.collectorId, fromCollectorId))
+    .run();
+
+  revalidateEverything();
+  return actionOk();
+}
+
+/** Reorders the collectors; the first one is the default for new entries. */
+export async function reorderCollectors(orderedIds: string[]): Promise<ActionResult> {
+  await requireUser();
+
+  db.transaction((tx) => {
+    orderedIds.forEach((id, index) => {
+      tx.update(collector)
+        .set({ sortOrder: index, updatedAt: now() })
+        .where(eq(collector.id, id))
+        .run();
+    });
+  });
+
+  revalidateEverything();
+  return actionOk();
+}
+
+/** Every collector, ordered - for the selects in the forms. */
+export async function listCollectorOptions(): Promise<Array<{ id: string; name: string }>> {
+  await requireUser();
+
+  return db
+    .select({ id: collector.id, name: collector.name })
+    .from(collector)
+    .orderBy(asc(collector.sortOrder), asc(collector.name))
+    .all();
+}

src/app/(app)/verwaltung/sammler/page.tsx

@@ -0,0 +1,40 @@
+import type { Metadata } from 'next';
+import { CollectorList, type CollectorRowItem } from '@/components/verwaltung/collector-list';
+import { formatDate, pluralize } from '@/lib/format';
+import { COLLECTOR_COLOR_LABELS } from '@/lib/collector-colors';
+import { listCollectors } from '@/lib/queries/collectors';
+import { requireUser } from '@/lib/session';
+
+export const metadata: Metadata = { title: 'Sammler' };
+
+export default async function SammlerPage() {
+  await requireUser();
+
+  const collectors = listCollectors();
+  const rows: CollectorRowItem[] = collectors.map((row) => ({
+    id: row.id,
+    title: row.name,
+    subtitle: [
+      pluralize(row.itemCount, 'Set', 'Sets'),
+      COLLECTOR_COLOR_LABELS[row.color],
+      row.birthday ? `geboren am ${formatDate(row.birthday)}` : null,
+    ]
+      .filter(Boolean)
+      .join(' · '),
+    color: row.color,
+    birthday: row.birthday,
+    notes: row.notes,
+    itemCount: row.itemCount,
+  }));
+
+  return (
+    <div className="space-y-4">
+      <p className="rounded-lg border border-dashed border-border p-4 text-sm text-muted-foreground">
+        Der Katalog ist gemeinsam: Ein Set existiert einmal, unabhängig davon, wer es hat.
+        Sammlung und Wunschlisten gehören dagegen je einem Sammler. Solange es nur einen gibt,
+        taucht die Unterscheidung nirgends in der App auf – sie erscheint erst mit dem zweiten.
+      </p>
+      <CollectorList collectors={rows} />
+    </div>
+  );
+}

src/app/(app)/wunschlisten/[id]/page.tsx

@@ -8,10 +8,12 @@ import { WishlistHeaderActions } from '@/components/wunschlisten/wishlist-header
 import { WishlistItems } from '@/components/wunschlisten/wishlist-items';
 import { Badge } from '@/components/ui/badge';
 import { Card, CardContent, CardDescription, CardHeader, CardTitle } from '@/components/ui/card';
+import { collectorBadgeClass } from '@/lib/collector-colors';
 import { formatDate, pluralize } from '@/lib/format';
 import { occasionLabel } from '@/lib/labels';
 import { CATALOG_PAGE_SIZE, listSets, listSetYears } from '@/lib/queries/catalog';
 import { listManufacturers, listThemes } from '@/lib/queries/master-data';
+import { listCollectors } from '@/lib/queries/collectors';
 import { getWishlist, listWishlistItems } from '@/lib/queries/wishlists';
 import { requireUser } from '@/lib/session';
 
@@ -39,7 +41,9 @@ export default async function WunschlisteDetailPage({ params, searchParams }: Pr
   const list = getWishlist(id);
   if (!list || list.ownerUserId !== user.id) notFound();
 
-  const items = listWishlistItems(list.id);
+  const collectors = listCollectors();
+  const activeCollector = collectors.find((row) => row.id === list.collectorId) ?? null;
+  const items = listWishlistItems(list.id, list.collectorId);
 
   // The embedded picker: missing sets that are not on this list yet. It shares
   // the URL parameters with the catalog, so the filters behave identically.
@@ -52,6 +56,7 @@ export default async function WunschlisteDetailPage({ params, searchParams }: Pr
     year: yearParam ? Number(yearParam) : undefined,
     ownership: 'fehlt',
     excludeWishlistId: list.id,
+    collectorId: list.collectorId ?? undefined,
     page,
   });
 
@@ -63,6 +68,11 @@ export default async function WunschlisteDetailPage({ params, searchParams }: Pr
             <Badge variant="secondary">{occasionLabel(list.occasion)}</Badge>
             {list.eventDate ? <Badge variant="outline">{formatDate(list.eventDate)}</Badge> : null}
             {list.surpriseMode ? <Badge variant="outline">Überraschungsmodus</Badge> : null}
+            {collectors.length > 1 && activeCollector ? (
+              <Badge className={collectorBadgeClass(activeCollector.color)}>
+                für {activeCollector.name}
+              </Badge>
+            ) : null}
           </div>
           <h1 className="mt-2 truncate text-2xl font-semibold tracking-tight">{list.title}</h1>
           <p className="text-sm text-muted-foreground">
@@ -70,8 +80,10 @@ export default async function WunschlisteDetailPage({ params, searchParams }: Pr
           </p>
         </div>
         <WishlistHeaderActions
+          collectors={collectors.map((row) => ({ id: row.id, name: row.name }))}
           wishlist={{
             id: list.id,
+            collectorId: list.collectorId,
             title: list.title,
             occasion: list.occasion,
             eventDate: list.eventDate,
@@ -99,7 +111,9 @@ export default async function WunschlisteDetailPage({ params, searchParams }: Pr
         <CardHeader>
           <CardTitle>Aus fehlenden Sets hinzufügen</CardTitle>
           <CardDescription>
-            Nur Sets, die noch nicht in der Sammlung und noch nicht auf dieser Liste sind. Kachel
+            {activeCollector
+              ? `Nur Sets, die ${activeCollector.name} noch nicht hat und die noch nicht auf dieser Liste stehen.`
+              : 'Nur Sets, die noch nicht in der Sammlung und noch nicht auf dieser Liste sind.'}{' '} Kachel
             lange drücken oder „Auswählen“ tippen, dann mehrere auf einmal übernehmen.
           </CardDescription>
         </CardHeader>
@@ -124,6 +138,7 @@ export default async function WunschlisteDetailPage({ params, searchParams }: Pr
             sets={missing.rows}
             wishlists={[{ id: list.id, title: list.title }]}
             defaultWishlistId={list.id}
+            collectorId={list.collectorId ?? undefined}
             emptyState="Es fehlt gerade nichts, was noch nicht auf dieser Liste steht."
           />
 

src/app/(app)/wunschlisten/actions.ts

@@ -12,6 +12,7 @@ import {
   type ActionResult,
 } from '@/lib/action-result';
 import { ownedCopiesSql } from '@/lib/ownership';
+import { defaultCollectorId } from '@/lib/queries/collectors';
 import {
   findExistingWishlistSetIds,
   getWishlist,
@@ -58,6 +59,7 @@ export async function createWishlist(input: unknown): Promise<ActionResult<{ id:
     .values({
       id,
       ownerUserId: user.id,
+      collectorId: parsed.data.collectorId ?? defaultCollectorId(),
       title: parsed.data.title,
       occasion: parsed.data.occasion,
       eventDate: parsed.data.eventDate,
@@ -83,6 +85,7 @@ export async function updateWishlist(id: string, input: unknown): Promise<Action
 
   db.update(wishlist)
     .set({
+      collectorId: parsed.data.collectorId,
       title: parsed.data.title,
       occasion: parsed.data.occasion,
       eventDate: parsed.data.eventDate,
@@ -153,7 +156,7 @@ export async function addSetsToWishlist(
       id: set.id,
       name: set.name,
       setNumber: set.setNumber,
-      ownedCopies: ownedCopiesSql(set.id).mapWith(Number),
+      ownedCopies: ownedCopiesSql(set.id, list.collectorId).mapWith(Number),
     })
     .from(set)
     .where(inArray(set.id, setIds))

src/app/(app)/wunschlisten/page.tsx

@@ -4,8 +4,10 @@ import { CalendarDays, Gift, Link2Off } from 'lucide-react';
 import { NewWishlistButton } from '@/components/wunschlisten/wishlist-form-dialog';
 import { Badge } from '@/components/ui/badge';
 import { Card, CardContent, CardDescription, CardHeader, CardTitle } from '@/components/ui/card';
+import { collectorBadgeClass } from '@/lib/collector-colors';
 import { formatDate, pluralize } from '@/lib/format';
 import { occasionLabel } from '@/lib/labels';
+import { listCollectors } from '@/lib/queries/collectors';
 import { listWishlists } from '@/lib/queries/wishlists';
 import { requireUser } from '@/lib/session';
 
@@ -14,6 +16,7 @@ export const metadata: Metadata = { title: 'Wunschlisten' };
 export default async function WunschlistenPage() {
   const user = await requireUser();
   const lists = listWishlists(user.id);
+  const collectors = listCollectors();
 
   return (
     <div className="space-y-5">
@@ -24,7 +27,9 @@ export default async function WunschlistenPage() {
             Zum Teilen mit Familie und Freunden – ganz ohne Konto für die anderen.
           </p>
         </div>
-        <NewWishlistButton />
+        <NewWishlistButton
+          collectors={collectors.map((row) => ({ id: row.id, name: row.name }))}
+        />
       </div>
 
       {lists.length === 0 ? (
@@ -54,6 +59,11 @@ export default async function WunschlistenPage() {
                     </CardDescription>
                   </CardHeader>
                   <CardContent className="flex flex-wrap items-center gap-2 text-xs">
+                    {collectors.length > 1 && list.collectorName ? (
+                      <Badge className={collectorBadgeClass(list.collectorColor)}>
+                        {list.collectorName}
+                      </Badge>
+                    ) : null}
                     <Badge variant="secondary">{pluralize(list.itemCount, 'Wunsch', 'Wünsche')}</Badge>
                     {list.openCount > 0 ? (
                       <Badge variant="outline">{list.openCount} noch offen</Badge>

src/app/api/health/route.ts

@@ -1,6 +1,7 @@
 import { sql } from 'drizzle-orm';
 import { NextResponse } from 'next/server';
 import { db } from '@/db';
+import { ensureReminderScheduler } from '@/lib/reminder-job';
 
 export const dynamic = 'force-dynamic';
 
@@ -9,6 +10,10 @@ export const dynamic = 'force-dynamic';
  * file is readable - a healthy Node process on a broken volume is not healthy.
  */
 export function GET() {
+  // The container polls this every 30s, which makes it the earliest reliable
+  // moment to have the reminder scheduler running. Repeat calls are free.
+  ensureReminderScheduler();
+
   try {
     db.get(sql`select 1`);
     return NextResponse.json({ status: 'ok', time: new Date().toISOString() });

src/app/w/[shareToken]/page.tsx

@@ -27,7 +27,7 @@ export default async function PublicWishlistPage({ params }: Props) {
   const list = getWishlistByShareToken(shareToken);
   if (!list || !list.isPublic) notFound();
 
-  const rows = listWishlistItems(list.id);
+  const rows = listWishlistItems(list.id, list.collectorId);
 
   // Fulfilled wishes are gone from the public view: the present is already
   // under the tree, no reason to let someone buy it twice.

src/components/katalog/catalog-grid.tsx

@@ -33,6 +33,8 @@ type Props = {
   wishlists: WishlistTarget[];
   /** Preselected target, used by the embedded view on a wishlist page. */
   defaultWishlistId?: string;
+  /** A list created from a filtered view belongs to that collector. */
+  collectorId?: string;
   emptyState?: React.ReactNode;
 };
 
@@ -43,7 +45,13 @@ type Props = {
  * On a desktop the "Auswählen" button does the same job. Sets that are already
  * in the collection cannot be selected - they do not belong on a wishlist.
  */
-export function CatalogGrid({ sets, wishlists, defaultWishlistId, emptyState }: Props) {
+export function CatalogGrid({
+  sets,
+  wishlists,
+  defaultWishlistId,
+  collectorId,
+  emptyState,
+}: Props) {
   const router = useRouter();
   const [selecting, setSelecting] = useState(false);
   const [selected, setSelected] = useState<Set<string>>(new Set());
@@ -102,6 +110,7 @@ export function CatalogGrid({ sets, wishlists, defaultWishlistId, emptyState }:
           title: newTitle,
           occasion: 'other',
           isPublic: 'on',
+          collectorId: collectorId ?? '',
         });
         if (!created.ok) {
           toast.error(created.error);
@@ -199,6 +208,7 @@ export function CatalogGrid({ sets, wishlists, defaultWishlistId, emptyState }:
             <button
               key={item.id}
               type="button"
+              data-set-card
               disabled={owned}
               aria-pressed={isSelected}
               onClick={() => toggle(item.id)}

src/components/katalog/price-section.tsx

@@ -0,0 +1,206 @@
+'use client';
+
+import { useRouter } from 'next/navigation';
+import { useState, useTransition } from 'react';
+import { Loader2, Plus, TrendingDown, TrendingUp, Trash2 } from 'lucide-react';
+import { toast } from 'sonner';
+import { addPricePoint, deletePricePoint } from '@/app/(app)/katalog/price-actions';
+import { formatDate, toDateInputValue } from '@/lib/format';
+import { formatEuro } from '@/lib/money';
+import { priceTrend, type PriceObservation } from '@/lib/prices';
+import type { PricePointRow } from '@/lib/queries/catalog';
+import { Badge } from '@/components/ui/badge';
+import { Button } from '@/components/ui/button';
+import { Field } from '@/components/ui/field';
+import { Input } from '@/components/ui/input';
+import { NativeSelect } from '@/components/ui/native-select';
+
+const CONDITION_LABELS: Record<string, string> = {
+  new: 'Neu',
+  used: 'Gebraucht',
+};
+
+/**
+ * Observed prices for one set.
+ *
+ * The point is not the single current price but the development: what a set
+ * did since it was bought. Everything here is maintained by hand - no price
+ * service is queried, and nothing leaves the server.
+ */
+export function PriceSection({
+  setId,
+  prices,
+  retailPriceCents,
+}: {
+  setId: string;
+  prices: PricePointRow[];
+  retailPriceCents: number | null;
+}) {
+  const router = useRouter();
+  const [pending, startTransition] = useTransition();
+  const [open, setOpen] = useState(false);
+
+  const observations: PriceObservation[] = prices.map((price) => ({
+    priceCents: price.priceCents,
+    condition: price.condition,
+    observedAt: price.observedAt,
+  }));
+  const trend = priceTrend(observations, retailPriceCents);
+  const gained = (trend.changeCents ?? 0) > 0;
+
+  function submit(event: React.FormEvent<HTMLFormElement>) {
+    event.preventDefault();
+    const form = event.currentTarget;
+    const input = Object.fromEntries(new FormData(form).entries());
+
+    startTransition(async () => {
+      const result = await addPricePoint(setId, input);
+      if (!result.ok) {
+        toast.error(result.error);
+        return;
+      }
+      form.reset();
+      setOpen(false);
+      toast.success('Preis notiert.');
+      router.refresh();
+    });
+  }
+
+  function remove(id: string) {
+    startTransition(async () => {
+      const result = await deletePricePoint(id);
+      if (!result.ok) {
+        toast.error(result.error);
+        return;
+      }
+      toast.success('Eintrag gelöscht.');
+      router.refresh();
+    });
+  }
+
+  return (
+    <div className="space-y-4">
+      <dl className="grid grid-cols-3 gap-3 text-sm">
+        <div>
+          <dt className="text-xs text-muted-foreground">Ursprünglich</dt>
+          <dd className="font-medium">{formatEuro(trend.baseCents)}</dd>
+        </div>
+        <div>
+          <dt className="text-xs text-muted-foreground">Aktuell</dt>
+          <dd className="font-medium">{formatEuro(trend.currentCents)}</dd>
+        </div>
+        <div>
+          <dt className="text-xs text-muted-foreground">Entwicklung</dt>
+          <dd>
+            {trend.changePercent === null ? (
+              <span className="text-muted-foreground">–</span>
+            ) : (
+              <span
+                className={`flex items-center gap-1 font-medium ${
+                  gained ? 'text-emerald-600' : 'text-muted-foreground'
+                }`}
+              >
+                {gained ? (
+                  <TrendingUp className="size-4" aria-hidden />
+                ) : (
+                  <TrendingDown className="size-4" aria-hidden />
+                )}
+                {trend.changePercent > 0 ? '+' : ''}
+                {trend.changePercent.toLocaleString('de-DE')} %
+              </span>
+            )}
+          </dd>
+        </div>
+      </dl>
+
+      {prices.length > 0 ? (
+        <ul className="divide-y divide-border rounded-lg border border-border">
+          {prices.map((price) => (
+            <li key={price.id} className="flex items-center gap-3 p-3">
+              <div className="min-w-0 flex-1">
+                <p className="text-sm font-medium">
+                  {formatEuro(price.priceCents)}{' '}
+                  <Badge variant="secondary">{CONDITION_LABELS[price.condition]}</Badge>
+                </p>
+                <p className="truncate text-xs text-muted-foreground">
+                  {[formatDate(price.observedAt), price.source, price.note]
+                    .filter(Boolean)
+                    .join(' · ')}
+                </p>
+              </div>
+              <Button
+                variant="ghost"
+                size="icon-sm"
+                aria-label="Preis löschen"
+                onClick={() => remove(price.id)}
+                disabled={pending}
+              >
+                <Trash2 className="text-destructive" />
+              </Button>
+            </li>
+          ))}
+        </ul>
+      ) : (
+        <p className="text-sm text-muted-foreground">
+          Noch kein Preis notiert. Der Ausgangswert ist die UVP des Sets.
+        </p>
+      )}
+
+      {open ? (
+        <form onSubmit={submit} className="space-y-3 rounded-lg border border-border p-3">
+          <p className="text-sm font-medium">Preis notieren</p>
+
+          <div className="grid gap-3 sm:grid-cols-3">
+            <Field label="Preis" htmlFor="priceCents" required hint="In Euro.">
+              <Input
+                id="priceCents"
+                name="priceCents"
+                inputMode="decimal"
+                required
+                placeholder="79,99"
+              />
+            </Field>
+            <Field label="Zustand" htmlFor="condition">
+              <NativeSelect id="condition" name="condition" defaultValue="new">
+                <option value="new">Neu</option>
+                <option value="used">Gebraucht</option>
+              </NativeSelect>
+            </Field>
+            <Field label="Gesehen am" htmlFor="observedAt" hint="Leer = heute.">
+              <Input
+                id="observedAt"
+                name="observedAt"
+                type="date"
+                defaultValue={toDateInputValue(new Date())}
+              />
+            </Field>
+          </div>
+
+          <div className="grid gap-3 sm:grid-cols-2">
+            <Field label="Wo" htmlFor="source">
+              <Input id="source" name="source" maxLength={80} placeholder="Amazon, Flohmarkt …" />
+            </Field>
+            <Field label="Notiz" htmlFor="price-note">
+              <Input id="price-note" name="note" maxLength={200} />
+            </Field>
+          </div>
+
+          <div className="flex gap-2">
+            <Button type="submit" disabled={pending}>
+              {pending ? <Loader2 className="animate-spin" /> : <Plus />}
+              Speichern
+            </Button>
+            <Button type="button" variant="outline" onClick={() => setOpen(false)}>
+              Abbrechen
+            </Button>
+          </div>
+        </form>
+      ) : (
+        <Button variant="outline" onClick={() => setOpen(true)}>
+          <Plus />
+          Preis notieren
+        </Button>
+      )}
+    </div>
+  );
+}

src/components/katalog/set-actions.tsx

@@ -38,32 +38,47 @@ export function SetActions({
   setName,
   owned,
   wishlists,
+  collectors,
 }: {
   setId: string;
   setName: string;
   owned: boolean;
   wishlists: Array<{ id: string; title: string }>;
+  /** More than one turns "Zur Sammlung" into a question of "for whom". */
+  collectors: Array<{ id: string; name: string }>;
 }) {
   const router = useRouter();
   const [pending, startTransition] = useTransition();
   const [wishlistOpen, setWishlistOpen] = useState(false);
   const [deleteOpen, setDeleteOpen] = useState(false);
   const [targetId, setTargetId] = useState(wishlists[0]?.id ?? NEW_LIST);
+  const [collectorOpen, setCollectorOpen] = useState(false);
+  const [collectorId, setCollectorId] = useState(collectors[0]?.id ?? '');
   const [newTitle, setNewTitle] = useState('');
   const [priority, setPriority] = useState('2');
 
-  function addToCollection() {
+  function addToCollection(forCollectorId?: string) {
     startTransition(async () => {
-      const result = await addSetToCollection(setId);
+      const result = await addSetToCollection(setId, forCollectorId);
       if (!result.ok) {
         toast.error(result.error);
         return;
       }
-      toast.success('Zur Sammlung hinzugefügt.');
+      const owner = collectors.find((entry) => entry.id === forCollectorId);
+      toast.success(
+        owner ? `Zur Sammlung von ${owner.name} hinzugefügt.` : 'Zur Sammlung hinzugefügt.',
+      );
+      setCollectorOpen(false);
       router.refresh();
     });
   }
 
+  // With a single collector there is nothing to ask.
+  function onAddClick() {
+    if (collectors.length > 1) setCollectorOpen(true);
+    else addToCollection();
+  }
+
   function addToWishlist() {
     startTransition(async () => {
       let wishlistId = targetId;
@@ -111,7 +126,7 @@ export function SetActions({
 
   return (
     <div className="flex flex-wrap gap-2">
-      <Button size="lg" onClick={addToCollection} disabled={pending}>
+      <Button size="lg" onClick={onAddClick} disabled={pending}>
         {pending ? <Loader2 className="animate-spin" /> : <Plus />}
         Zur Sammlung hinzufügen
       </Button>
@@ -138,6 +153,39 @@ export function SetActions({
         </p>
       ) : null}
 
+      <Dialog open={collectorOpen} onOpenChange={setCollectorOpen}>
+        <DialogContent>
+          <DialogHeader>
+            <DialogTitle>Wer bekommt das Set?</DialogTitle>
+            <DialogDescription>{setName}</DialogDescription>
+          </DialogHeader>
+
+          <Field label="Sammler" htmlFor="add-collector" required>
+            <NativeSelect
+              id="add-collector"
+              value={collectorId}
+              onChange={(event) => setCollectorId(event.target.value)}
+            >
+              {collectors.map((entry) => (
+                <option key={entry.id} value={entry.id}>
+                  {entry.name}
+                </option>
+              ))}
+            </NativeSelect>
+          </Field>
+
+          <DialogFooter>
+            <Button variant="outline" onClick={() => setCollectorOpen(false)} disabled={pending}>
+              Abbrechen
+            </Button>
+            <Button onClick={() => addToCollection(collectorId)} disabled={pending}>
+              {pending ? <Loader2 className="animate-spin" /> : <Plus />}
+              Hinzufügen
+            </Button>
+          </DialogFooter>
+        </DialogContent>
+      </Dialog>
+
       <Dialog open={wishlistOpen} onOpenChange={setWishlistOpen}>
         <DialogContent>
           <DialogHeader>

src/components/katalog/set-form.tsx

@@ -1,13 +1,28 @@
 'use client';
 
 import { useRouter } from 'next/navigation';
-import { useState, useTransition } from 'react';
+import { useRef, useState, useTransition } from 'react';
+import Link from 'next/link';
 import { Loader2, Save } from 'lucide-react';
 import { toast } from 'sonner';
 import { createSet, updateSet } from '@/app/(app)/katalog/actions';
+import {
+  findDuplicateCandidates,
+  type DuplicateCandidate,
+} from '@/app/(app)/katalog/duplicate-actions';
 import { centsToInput } from '@/lib/money';
 import { setImageSrc } from '@/lib/images';
 import { Button } from '@/components/ui/button';
+import {
+  AlertDialog,
+  AlertDialogAction,
+  AlertDialogCancel,
+  AlertDialogContent,
+  AlertDialogDescription,
+  AlertDialogFooter,
+  AlertDialogHeader,
+  AlertDialogTitle,
+} from '@/components/ui/alert-dialog';
 import { Checkbox } from '@/components/ui/checkbox';
 import { Field } from '@/components/ui/field';
 import { Input } from '@/components/ui/input';
@@ -46,6 +61,8 @@ export function SetForm({ manufacturers, themes, set, defaultEan }: Props) {
   const [manufacturerId, setManufacturerId] = useState(
     set?.manufacturerId ?? manufacturers[0]?.id ?? '',
   );
+  const [duplicates, setDuplicates] = useState<DuplicateCandidate[] | null>(null);
+  const pendingForm = useRef<FormData | null>(null);
 
   const existingImage = set ? setImageSrc(set) : null;
   const availableThemes = themes.filter((theme) => theme.manufacturerId === manufacturerId);
@@ -54,31 +71,69 @@ export function SetForm({ manufacturers, themes, set, defaultEan }: Props) {
     event.preventDefault();
     const formData = new FormData(event.currentTarget);
 
+    // Ask before creating something that already exists. Editing skips this:
+    // there the entry is the one we would be warning about.
+    if (!set) {
+      startTransition(async () => {
+        const check = await findDuplicateCandidates({
+          manufacturerId: String(formData.get('manufacturerId') ?? ''),
+          setNumber: String(formData.get('setNumber') ?? ''),
+          name: String(formData.get('name') ?? ''),
+        });
+
+        if (check.ok && check.data.candidates.length > 0) {
+          pendingForm.current = formData;
+          setDuplicates(check.data.candidates);
+          return;
+        }
+
+        await save(formData);
+      });
+      return;
+    }
+
+    startTransition(() => save(formData));
+  }
+
+  async function save(formData: FormData) {
+    return new Promise<void>((resolve) => {
       startTransition(async () => {
         if (set) {
           const result = await updateSet(set.id, formData);
           if (!result.ok) {
             toast.error(result.error);
+            resolve();
             return;
           }
           toast.success('Set gespeichert.');
           router.push(`/katalog/${set.id}`);
           router.refresh();
+          resolve();
           return;
         }
 
         const result = await createSet(formData);
         if (!result.ok) {
           toast.error(result.error);
+          resolve();
           return;
         }
         toast.success('Set angelegt.');
         router.push(`/katalog/${result.data.id}`);
         router.refresh();
+        resolve();
+      });
     });
   }
 
+  const REASON_LABELS: Record<DuplicateCandidate['reason'], string> = {
+    'same-number': 'Gleiche Setnummer beim gleichen Hersteller',
+    'similar-name': 'Sehr ähnlicher Name',
+    'number-elsewhere': 'Gleiche Setnummer bei einem anderen Hersteller',
+  };
+
   return (
+    <>
       <form onSubmit={onSubmit} className="space-y-6">
       <div className="grid gap-4 sm:grid-cols-2">
         <Field label="Hersteller" htmlFor="manufacturerId" required>
@@ -244,5 +299,56 @@ export function SetForm({ manufacturers, themes, set, defaultEan }: Props) {
         </Button>
       </div>
       </form>
+
+      <AlertDialog
+        open={duplicates !== null}
+        onOpenChange={(open) => {
+          if (!open) {
+            setDuplicates(null);
+            pendingForm.current = null;
+          }
+        }}
+      >
+        <AlertDialogContent>
+          <AlertDialogHeader>
+            <AlertDialogTitle>Gibt es das vielleicht schon?</AlertDialogTitle>
+            <AlertDialogDescription>
+              Diese Einträge sehen ähnlich aus. Schau kurz nach, bevor der Katalog zwei Mal
+              dasselbe Set enthält.
+            </AlertDialogDescription>
+          </AlertDialogHeader>
+
+          <ul className="divide-y divide-border rounded-lg border border-border">
+            {(duplicates ?? []).map((candidate) => (
+              <li key={candidate.id} className="p-3">
+                <Link
+                  href={`/katalog/${candidate.id}`}
+                  className="text-sm font-medium hover:underline"
+                >
+                  {candidate.setNumber} · {candidate.name}
+                </Link>
+                <p className="text-xs text-muted-foreground">
+                  {candidate.manufacturerName} — {REASON_LABELS[candidate.reason]}
+                </p>
+              </li>
+            ))}
+          </ul>
+
+          <AlertDialogFooter>
+            <AlertDialogCancel>Zurück zum Formular</AlertDialogCancel>
+            <AlertDialogAction
+              onClick={() => {
+                const formData = pendingForm.current;
+                setDuplicates(null);
+                pendingForm.current = null;
+                if (formData) void save(formData);
+              }}
+            >
+              Trotzdem anlegen
+            </AlertDialogAction>
+          </AlertDialogFooter>
+        </AlertDialogContent>
+      </AlertDialog>
+    </>
   );
 }

src/components/layout/collector-filter.tsx

@@ -0,0 +1,78 @@
+'use client';
+
+import { usePathname, useRouter, useSearchParams } from 'next/navigation';
+import { useTransition } from 'react';
+import { cn } from 'cn';
+import { collectorDotClass } from '@/lib/collector-colors';
+
+export type CollectorOption = { id: string; name: string; color: string };
+
+/**
+ * Switches the view between collectors.
+ *
+ * Rendered only when there is more than one - with a single collector the
+ * whole question does not exist, and the app should not ask it. The choice
+ * lives in the URL (`?sammler=`), so a filtered view stays shareable and the
+ * back button behaves.
+ */
+export function CollectorFilter({
+  collectors,
+  allLabel = 'Alle',
+}: {
+  collectors: CollectorOption[];
+  allLabel?: string;
+}) {
+  const router = useRouter();
+  const pathname = usePathname();
+  const searchParams = useSearchParams();
+  const [, startTransition] = useTransition();
+
+  if (collectors.length < 2) return null;
+
+  const current = searchParams.get('sammler') ?? '';
+
+  function select(id: string) {
+    const params = new URLSearchParams(searchParams.toString());
+    if (id) params.set('sammler', id);
+    else params.delete('sammler');
+    params.delete('seite');
+
+    const query = params.toString();
+    startTransition(() => router.push(query ? `${pathname}?${query}` : pathname));
+  }
+
+  const options = [{ id: '', name: allLabel, color: 'slate' }, ...collectors];
+
+  return (
+    <nav
+      aria-label="Sammler"
+      className="flex gap-1 overflow-x-auto rounded-lg bg-muted p-1"
+    >
+      {options.map((option) => {
+        const active = current === option.id;
+        return (
+          <button
+            key={option.id || 'alle'}
+            type="button"
+            aria-pressed={active}
+            onClick={() => select(option.id)}
+            className={cn(
+              'flex flex-1 items-center justify-center gap-2 rounded-md px-3 py-2 text-sm font-medium whitespace-nowrap transition-colors',
+              active
+                ? 'bg-background text-foreground shadow-sm'
+                : 'text-muted-foreground hover:text-foreground',
+            )}
+          >
+            {option.id ? (
+              <span
+                className={cn('size-2 rounded-full', collectorDotClass(option.color))}
+                aria-hidden
+              />
+            ) : null}
+            {option.name}
+          </button>
+        );
+      })}
+    </nav>
+  );
+}

src/components/sammlung/collection-items-section.tsx

@@ -8,6 +8,7 @@ import { deleteCollectionItem, updateCollectionItem } from '@/app/(app)/sammlung
 import type { MissingPartRow } from '@/lib/queries/collection';
 import { MissingPartsDialog } from './missing-parts-dialog';
 import type { CollectionStatus, Completeness, Condition } from '@/db/types';
+import { collectorBadgeClass } from '@/lib/collector-colors';
 import { formatDate, toDateInputValue } from '@/lib/format';
 import {
   COMPLETENESS_LABELS,
@@ -58,14 +59,19 @@ export type CollectionItemRow = {
   notes: string | null;
   setName: string;
   missingParts: MissingPartRow[];
+  collectorId: string | null;
+  collectorName: string | null;
+  collectorColor: string | null;
 };
 
 export function CollectionItemsSection({
   items,
   locations,
+  collectors,
 }: {
   items: CollectionItemRow[];
   locations: Array<{ id: string; name: string }>;
+  collectors: Array<{ id: string; name: string }>;
 }) {
   const router = useRouter();
   const [pending, startTransition] = useTransition();
@@ -126,6 +132,11 @@ export function CollectionItemsSection({
           <li key={item.id} className="flex items-start gap-3 p-3">
             <div className="min-w-0 flex-1 space-y-1">
               <div className="flex flex-wrap items-center gap-2">
+                {collectors.length > 1 && item.collectorName ? (
+                  <Badge className={collectorBadgeClass(item.collectorColor)}>
+                    {item.collectorName}
+                  </Badge>
+                ) : null}
                 <Badge variant={item.status === 'sold' ? 'outline' : 'default'}>
                   {statusLabel(item.status)}
                 </Badge>
@@ -194,6 +205,22 @@ export function CollectionItemsSection({
 
           <form id="collection-item-form" onSubmit={submit} className="space-y-4">
             <div className="grid gap-4 sm:grid-cols-2">
+              {collectors.length > 1 ? (
+                <Field label="Sammler" htmlFor="collectorId" className="sm:col-span-2">
+                  <NativeSelect
+                    id="collectorId"
+                    name="collectorId"
+                    defaultValue={editing?.collectorId ?? collectors[0]?.id ?? 'none'}
+                  >
+                    {collectors.map((entry) => (
+                      <option key={entry.id} value={entry.id}>
+                        {entry.name}
+                      </option>
+                    ))}
+                  </NativeSelect>
+                </Field>
+              ) : null}
+
               <Field label="Status" htmlFor="status">
                 <NativeSelect id="status" name="status" defaultValue={editing?.status ?? 'owned'}>
                   {Object.entries(STATUS_LABELS).map(([value, label]) => (

src/components/verwaltung/collector-list.tsx

@@ -0,0 +1,87 @@
+'use client';
+
+import {
+  createCollector,
+  deleteCollector,
+  updateCollector,
+} from '@/app/(app)/verwaltung/sammler/actions';
+import { COLLECTOR_COLOR_LABELS } from '@/lib/collector-colors';
+import { toDateInputValue } from '@/lib/format';
+import { CrudSection, type CrudItem } from './crud-section';
+import { Field } from '@/components/ui/field';
+import { Input } from '@/components/ui/input';
+import { NativeSelect } from '@/components/ui/native-select';
+import { Textarea } from '@/components/ui/textarea';
+
+export type CollectorRowItem = CrudItem & {
+  color: string;
+  birthday: Date | null;
+  notes: string | null;
+  itemCount: number;
+};
+
+export function CollectorList({ collectors }: { collectors: CollectorRowItem[] }) {
+  return (
+    <CrudSection<CollectorRowItem>
+      items={collectors}
+      emptyText="Noch kein Sammler angelegt."
+      createLabel="Sammler anlegen"
+      dialogTitle={(item) => (item ? 'Sammler bearbeiten' : 'Neuer Sammler')}
+      dialogDescription="Der Katalog bleibt gemeinsam – Sammlung und Wunschlisten gehören je einem Sammler."
+      onCreate={createCollector}
+      onUpdate={updateCollector}
+      onDelete={deleteCollector}
+      deleteWarning={(item) =>
+        item.itemCount > 0
+          ? `„${item.title}“ hat ${item.itemCount} Sets in der Sammlung. Ordne sie erst jemand anderem zu – erst dann lässt sich der Sammler löschen.`
+          : `„${item.title}“ wird gelöscht. Der Katalog bleibt unverändert.`
+      }
+      renderFields={(item) => (
+        <>
+          <Field label="Name" htmlFor="name" required>
+            <Input
+              id="name"
+              name="name"
+              defaultValue={item?.title ?? ''}
+              required
+              maxLength={60}
+              placeholder="Max"
+            />
+          </Field>
+
+          <Field
+            label="Farbe"
+            htmlFor="color"
+            hint="Nur zur Unterscheidung auf einen Blick."
+          >
+            <NativeSelect id="color" name="color" defaultValue={item?.color ?? 'blue'}>
+              {Object.entries(COLLECTOR_COLOR_LABELS).map(([value, label]) => (
+                <option key={value} value={value}>
+                  {label}
+                </option>
+              ))}
+            </NativeSelect>
+          </Field>
+
+          <Field label="Geburtstag" htmlFor="birthday" hint="Optional.">
+            <Input
+              id="birthday"
+              name="birthday"
+              type="date"
+              defaultValue={toDateInputValue(item?.birthday)}
+            />
+          </Field>
+
+          <Field label="Notizen" htmlFor="collector-notes">
+            <Textarea
+              id="collector-notes"
+              name="notes"
+              defaultValue={item?.notes ?? ''}
+              rows={3}
+            />
+          </Field>
+        </>
+      )}
+    />
+  );
+}

src/components/verwaltung/reminder-settings.tsx

@@ -0,0 +1,166 @@
+'use client';
+
+import { useState, useTransition } from 'react';
+import { BellRing, Loader2, Mail, PlugZap } from 'lucide-react';
+import { toast } from 'sonner';
+import {
+  runRemindersNow,
+  sendTestMail,
+  testMailConnection,
+} from '@/app/(app)/verwaltung/erinnerungen/actions';
+import { formatDate } from '@/lib/format';
+import { Badge } from '@/components/ui/badge';
+import { Button } from '@/components/ui/button';
+import { Card, CardContent, CardDescription, CardHeader, CardTitle } from '@/components/ui/card';
+
+export type ReminderListRow = {
+  id: string;
+  title: string;
+  eventDate: Date | null;
+  openItemCount: number;
+  lastReminderAt: Date | null;
+  daysLeft: number | null;
+};
+
+export function ReminderSettings({
+  configured,
+  daysBefore,
+  lists,
+}: {
+  configured: boolean;
+  daysBefore: number;
+  lists: ReminderListRow[];
+}) {
+  const [pending, startTransition] = useTransition();
+  const [busy, setBusy] = useState<'verify' | 'test' | 'run' | null>(null);
+
+  function run(kind: 'verify' | 'test' | 'run') {
+    setBusy(kind);
+    startTransition(async () => {
+      if (kind === 'verify') {
+        const result = await testMailConnection();
+        if (result.ok) toast.success('Der SMTP-Server antwortet.');
+        else toast.error(result.error);
+      }
+
+      if (kind === 'test') {
+        const result = await sendTestMail();
+        if (result.ok) toast.success('Testnachricht verschickt. Schau in dein Postfach.');
+        else toast.error(result.error);
+      }
+
+      if (kind === 'run') {
+        const result = await runRemindersNow();
+        if (!result.ok) {
+          toast.error(result.error);
+        } else if (result.data.sent === 0 && result.data.failures.length === 0) {
+          toast.info('Nichts zu tun – gerade steht keine Erinnerung an.');
+        } else {
+          toast.success(
+            `${result.data.sent} Erinnerung(en) verschickt, ${result.data.failures.length} fehlgeschlagen.`,
+          );
+        }
+      }
+
+      setBusy(null);
+    });
+  }
+
+  return (
+    <div className="space-y-6">
+      <Card>
+        <CardHeader>
+          <CardTitle className="flex items-center gap-2">
+            <BellRing className="size-5 text-primary" aria-hidden />
+            Erinnerungen
+          </CardTitle>
+          <CardDescription>
+            Rückt der Termin einer Wunschliste näher und stehen noch Wünsche offen, geht eine
+            Nachricht an dich raus – {daysBefore} Tage vorher, höchstens einmal pro Woche je Liste.
+          </CardDescription>
+        </CardHeader>
+        <CardContent className="space-y-4">
+          {configured ? (
+            <div className="flex flex-wrap gap-2">
+              <Button variant="outline" onClick={() => run('verify')} disabled={pending}>
+                {busy === 'verify' ? <Loader2 className="animate-spin" /> : <PlugZap />}
+                Verbindung prüfen
+              </Button>
+              <Button variant="outline" onClick={() => run('test')} disabled={pending}>
+                {busy === 'test' ? <Loader2 className="animate-spin" /> : <Mail />}
+                Testnachricht an mich
+              </Button>
+              <Button onClick={() => run('run')} disabled={pending}>
+                {busy === 'run' ? <Loader2 className="animate-spin" /> : <BellRing />}
+                Jetzt prüfen
+              </Button>
+            </div>
+          ) : (
+            <div className="space-y-2 rounded-lg border border-dashed border-border p-4 text-sm text-muted-foreground">
+              <p>
+                Es ist kein Mailversand eingerichtet – Erinnerungen sind damit aus, alles andere
+                funktioniert unverändert.
+              </p>
+              <p>Zum Aktivieren in die .env eintragen und den Container neu starten:</p>
+              <pre className="overflow-x-auto rounded-md bg-muted p-3 font-mono text-xs">
+{`SMTP_HOST=mail.example.de
+SMTP_PORT=587
+SMTP_USER=bricktrack@example.de
+SMTP_PASSWORD=…
+SMTP_FROM=Bricktrack <bricktrack@example.de>`}
+              </pre>
+            </div>
+          )}
+        </CardContent>
+      </Card>
+
+      <Card>
+        <CardHeader>
+          <CardTitle>Wunschlisten mit Termin</CardTitle>
+          <CardDescription>
+            Nur Listen mit Termin können erinnert werden. Ist alles reserviert, bleibt es still.
+          </CardDescription>
+        </CardHeader>
+        <CardContent>
+          {lists.length === 0 ? (
+            <p className="text-sm text-muted-foreground">
+              Keine Wunschliste hat bisher einen Termin.
+            </p>
+          ) : (
+            <ul className="divide-y divide-border rounded-lg border border-border">
+              {lists.map((list) => (
+                <li key={list.id} className="flex items-center gap-3 p-3">
+                  <div className="min-w-0 flex-1">
+                    <p className="truncate text-sm font-medium">{list.title}</p>
+                    <p className="text-xs text-muted-foreground">
+                      {list.eventDate ? formatDate(list.eventDate) : 'ohne Termin'}
+                      {list.lastReminderAt
+                        ? ` · zuletzt erinnert am ${formatDate(list.lastReminderAt)}`
+                        : ''}
+                    </p>
+                  </div>
+
+                  {list.openItemCount > 0 ? (
+                    <Badge variant="outline">{list.openItemCount} offen</Badge>
+                  ) : (
+                    <Badge className="bg-emerald-600 text-white hover:bg-emerald-600">
+                      Alles vergeben
+                    </Badge>
+                  )}
+
+                  {list.daysLeft !== null && list.daysLeft >= 0 ? (
+                    <Badge variant="secondary">
+                      {list.daysLeft === 0 ? 'heute' : `in ${list.daysLeft} Tagen`}
+                    </Badge>
+                  ) : (
+                    <Badge variant="outline">vorbei</Badge>
+                  )}
+                </li>
+              ))}
+            </ul>
+          )}
+        </CardContent>
+      </Card>
+    </div>
+  );
+}

src/components/verwaltung/verwaltung-nav.tsx

@@ -5,10 +5,12 @@ import { usePathname } from 'next/navigation';
 import { cn } from 'cn';
 
 const tabs = [
+  { href: '/verwaltung/sammler', label: 'Sammler', adminOnly: false },
   { href: '/verwaltung/hersteller', label: 'Hersteller', adminOnly: false },
   { href: '/verwaltung/themen', label: 'Themen', adminOnly: false },
   { href: '/verwaltung/standorte', label: 'Standorte', adminOnly: false },
   { href: '/verwaltung/einladungen', label: 'Einladungen', adminOnly: true },
+  { href: '/verwaltung/erinnerungen', label: 'Erinnerungen', adminOnly: true },
   { href: '/verwaltung/daten', label: 'Daten', adminOnly: true },
 ] as const;
 

src/components/wunschlisten/wishlist-form-dialog.tsx

@@ -26,6 +26,7 @@ import { Textarea } from '@/components/ui/textarea';
 
 export type WishlistFormValues = {
   id: string;
+  collectorId: string | null;
   title: string;
   occasion: Occasion;
   eventDate: Date | null;
@@ -36,10 +37,13 @@ export type WishlistFormValues = {
 
 export function WishlistFormDialog({
   wishlist,
+  collectors = [],
   open,
   onOpenChange,
 }: {
   wishlist?: WishlistFormValues;
+  /** Only asked about when there is more than one. */
+  collectors?: Array<{ id: string; name: string }>;
   open: boolean;
   onOpenChange: (open: boolean) => void;
 }) {
@@ -99,6 +103,27 @@ export function WishlistFormDialog({
               />
             </Field>
 
+            {collectors.length > 1 ? (
+              <Field
+                label="Für wen"
+                htmlFor="collectorId"
+                hint="Bestimmt, wessen Sammlung als „hat er schon“ zählt."
+              >
+                <NativeSelect
+                  id="collectorId"
+                  name="collectorId"
+                  defaultValue={wishlist?.collectorId ?? 'none'}
+                >
+                  <option value="none">– alle zusammen –</option>
+                  {collectors.map((entry) => (
+                    <option key={entry.id} value={entry.id}>
+                      {entry.name}
+                    </option>
+                  ))}
+                </NativeSelect>
+              </Field>
+            ) : null}
+
             <div className="grid gap-4 sm:grid-cols-2">
               <Field label="Anlass" htmlFor="occasion">
                 <NativeSelect
@@ -180,7 +205,11 @@ export function WishlistFormDialog({
 }
 
 /** Button plus dialog, for the wishlist overview page. */
-export function NewWishlistButton() {
+export function NewWishlistButton({
+  collectors = [],
+}: {
+  collectors?: Array<{ id: string; name: string }>;
+}) {
   const [open, setOpen] = useState(false);
 
   return (
@@ -189,7 +218,7 @@ export function NewWishlistButton() {
         <Plus />
         Neue Wunschliste
       </Button>
-      <WishlistFormDialog open={open} onOpenChange={setOpen} />
+      <WishlistFormDialog collectors={collectors} open={open} onOpenChange={setOpen} />
     </>
   );
 }

src/components/wunschlisten/wishlist-header-actions.tsx

@@ -18,7 +18,13 @@ import {
   AlertDialogTitle,
 } from '@/components/ui/alert-dialog';
 
-export function WishlistHeaderActions({ wishlist }: { wishlist: WishlistFormValues }) {
+export function WishlistHeaderActions({
+  wishlist,
+  collectors = [],
+}: {
+  wishlist: WishlistFormValues;
+  collectors?: Array<{ id: string; name: string }>;
+}) {
   const router = useRouter();
   const [editOpen, setEditOpen] = useState(false);
   const [deleteOpen, setDeleteOpen] = useState(false);
@@ -52,7 +58,12 @@ export function WishlistHeaderActions({ wishlist }: { wishlist: WishlistFormValu
         <Trash2 className="text-destructive" />
       </Button>
 
-      <WishlistFormDialog wishlist={wishlist} open={editOpen} onOpenChange={setEditOpen} />
+      <WishlistFormDialog
+        wishlist={wishlist}
+        collectors={collectors}
+        open={editOpen}
+        onOpenChange={setEditOpen}
+      />
 
       <AlertDialog open={deleteOpen} onOpenChange={setDeleteOpen}>
         <AlertDialogContent>

src/db/schema/collection.ts

@@ -8,6 +8,7 @@ import {
   text,
 } from 'drizzle-orm/sqlite-core';
 import { set } from './catalog';
+import { collector } from './collector';
 
 export const location = sqliteTable('location', {
   id: text('id').primaryKey(),
@@ -31,6 +32,12 @@ export const collectionItem = sqliteTable(
     setId: text('set_id')
       .notNull()
       .references(() => set.id, { onDelete: 'cascade' }),
+    /**
+     * Who owns this copy. Nullable only for the sake of the migration path -
+     * the app always sets it, and the migration assigned every existing row to
+     * the first collector.
+     */
+    collectorId: text('collector_id').references(() => collector.id, { onDelete: 'cascade' }),
     status: text('status', {
       enum: ['owned', 'built', 'disassembled', 'lent_out', 'sold'],
     })
@@ -54,6 +61,7 @@ export const collectionItem = sqliteTable(
   },
   (t) => [
     index('collection_item_set_idx').on(t.setId),
+    index('collection_item_collector_idx').on(t.collectorId),
     index('collection_item_status_idx').on(t.status),
     index('collection_item_location_idx').on(t.locationId),
   ],

src/db/schema/collector.ts

@@ -0,0 +1,29 @@
+import { index, integer, sqliteTable, text } from 'drizzle-orm/sqlite-core';
+
+/**
+ * A collector - in practice: a child.
+ *
+ * The catalog is shared (a set exists once, no matter who owns it), while
+ * ownership and wishlists belong to one collector. With a single collector the
+ * whole concept stays invisible in the UI; it only appears once a second one
+ * exists, so a one-child household never pays for the feature.
+ */
+export const collector = sqliteTable(
+  'collector',
+  {
+    id: text('id').primaryKey(),
+    name: text('name').notNull(),
+    /** For telling two collectors apart at a glance. */
+    color: text('color', {
+      enum: ['blue', 'green', 'amber', 'rose', 'violet', 'slate'],
+    })
+      .notNull()
+      .default('blue'),
+    birthday: integer('birthday', { mode: 'timestamp' }),
+    notes: text('notes'),
+    sortOrder: integer('sort_order').notNull().default(0),
+    createdAt: integer('created_at', { mode: 'timestamp' }).notNull(),
+    updatedAt: integer('updated_at', { mode: 'timestamp' }).notNull(),
+  },
+  (t) => [index('collector_sort_idx').on(t.sortOrder, t.name)],
+);

src/db/schema/index.ts

@@ -1,5 +1,7 @@
 export * from './auth';
 export * from './catalog';
+export * from './collector';
+export * from './prices';
 export * from './collection';
 export * from './wishlist';
 export * from './relations';

src/db/schema/prices.ts

@@ -0,0 +1,35 @@
+import { check, index, integer, sqliteTable, text } from 'drizzle-orm/sqlite-core';
+import { sql } from 'drizzle-orm';
+import { set } from './catalog';
+
+/**
+ * An observed price for a set at a point in time.
+ *
+ * Kept as a series rather than a single field, because the interesting
+ * question is not "what does it cost" but "what has it done since we bought
+ * it". Entries are maintained by hand - the UVP from the set itself is the
+ * starting point, everything after that is what you actually saw somewhere.
+ */
+export const pricePoint = sqliteTable(
+  'price_point',
+  {
+    id: text('id').primaryKey(),
+    setId: text('set_id')
+      .notNull()
+      .references(() => set.id, { onDelete: 'cascade' }),
+    /** EUR in cents, like every other amount in this app. */
+    priceCents: integer('price_cents').notNull(),
+    condition: text('condition', { enum: ['new', 'used'] })
+      .notNull()
+      .default('new'),
+    /** Where the price was seen, e.g. "Amazon", "Flohmarkt", "BrickLink". */
+    source: text('source'),
+    observedAt: integer('observed_at', { mode: 'timestamp' }).notNull(),
+    note: text('note'),
+    createdAt: integer('created_at', { mode: 'timestamp' }).notNull(),
+  },
+  (t) => [
+    index('price_point_set_idx').on(t.setId, t.observedAt),
+    check('price_point_positive', sql`${t.priceCents} >= 0`),
+  ],
+);

src/db/schema/relations.ts

@@ -2,6 +2,8 @@ import { relations } from 'drizzle-orm';
 import { passkey, session, user } from './auth';
 import { instruction, manufacturer, set, setTag, tag, theme } from './catalog';
 import { collectionItem, location, missingPart, photo } from './collection';
+import { collector } from './collector';
+import { pricePoint } from './prices';
 import { wishlist, wishlistItem } from './wishlist';
 
 export const userRelations = relations(user, ({ many }) => ({
@@ -48,6 +50,11 @@ export const setRelations = relations(set, ({ one, many }) => ({
   photos: many(photo),
   setTags: many(setTag),
   wishlistItems: many(wishlistItem),
+  pricePoints: many(pricePoint),
+}));
+
+export const pricePointRelations = relations(pricePoint, ({ one }) => ({
+  set: one(set, { fields: [pricePoint.setId], references: [set.id] }),
 }));
 
 export const tagRelations = relations(tag, ({ many }) => ({
@@ -73,8 +80,17 @@ export const locationRelations = relations(location, ({ one, many }) => ({
   collectionItems: many(collectionItem),
 }));
 
+export const collectorRelations = relations(collector, ({ many }) => ({
+  collectionItems: many(collectionItem),
+  wishlists: many(wishlist),
+}));
+
 export const collectionItemRelations = relations(collectionItem, ({ one, many }) => ({
   set: one(set, { fields: [collectionItem.setId], references: [set.id] }),
+  collector: one(collector, {
+    fields: [collectionItem.collectorId],
+    references: [collector.id],
+  }),
   location: one(location, {
     fields: [collectionItem.locationId],
     references: [location.id],
@@ -100,6 +116,10 @@ export const photoRelations = relations(photo, ({ one }) => ({
 
 export const wishlistRelations = relations(wishlist, ({ one, many }) => ({
   owner: one(user, { fields: [wishlist.ownerUserId], references: [user.id] }),
+  collector: one(collector, {
+    fields: [wishlist.collectorId],
+    references: [collector.id],
+  }),
   items: many(wishlistItem),
 }));
 

src/db/schema/wishlist.ts

@@ -2,6 +2,7 @@ import { sql } from 'drizzle-orm';
 import { check, index, integer, sqliteTable, text, uniqueIndex } from 'drizzle-orm/sqlite-core';
 import { user } from './auth';
 import { set } from './catalog';
+import { collector } from './collector';
 
 export const wishlist = sqliteTable(
   'wishlist',
@@ -10,6 +11,11 @@ export const wishlist = sqliteTable(
     ownerUserId: text('owner_user_id')
       .notNull()
       .references(() => user.id, { onDelete: 'cascade' }),
+    /**
+     * Whose list this is. Null means "not tied to one collector" - useful
+     * while there is only one, and for a shared list.
+     */
+    collectorId: text('collector_id').references(() => collector.id, { onDelete: 'set null' }),
     /** e.g. "Weihnachten 2026". */
     title: text('title').notNull(),
     occasion: text('occasion', { enum: ['christmas', 'birthday', 'easter', 'other'] })
@@ -23,6 +29,8 @@ export const wishlist = sqliteTable(
     surpriseMode: integer('surprise_mode', { mode: 'boolean' }).notNull().default(false),
     /** Message shown to the gift givers, e.g. "Bitte keine Doppelungen". */
     note: text('note'),
+    /** When the owner was last reminded - keeps a nag from becoming a flood. */
+    lastReminderAt: integer('last_reminder_at', { mode: 'timestamp' }),
     createdAt: integer('created_at', { mode: 'timestamp' }).notNull(),
     updatedAt: integer('updated_at', { mode: 'timestamp' }).notNull(),
   },

src/env.ts

@@ -27,8 +27,26 @@ const schema = z.object({
   /** Upload size limit per file, in megabytes. */
   MAX_UPLOAD_MB: z.coerce.number().int().positive().max(200).default(25),
 
-  /** Optional, phase 2: Rebrickable set import. Import stays disabled without it. */
+  /** Optional: Rebrickable set import. Import stays disabled without it. */
   REBRICKABLE_API_KEY: z.string().min(1).optional(),
+
+  /**
+   * Optional: outgoing mail for wishlist reminders. Without SMTP_HOST the
+   * whole reminder feature stays switched off - nothing is scheduled, nothing
+   * is sent.
+   */
+  SMTP_HOST: z.string().min(1).optional(),
+  SMTP_PORT: z.coerce.number().int().min(1).max(65535).default(587),
+  SMTP_SECURE: z
+    .enum(['true', 'false'])
+    .default('false')
+    .transform((value) => value === 'true'),
+  SMTP_USER: z.string().min(1).optional(),
+  SMTP_PASSWORD: z.string().min(1).optional(),
+  SMTP_FROM: z.string().min(1).optional(),
+
+  /** How many days before the event a reminder goes out. */
+  REMINDER_DAYS_BEFORE: z.coerce.number().int().min(1).max(90).default(14),
 });
 
 /**
@@ -82,6 +100,9 @@ export const env = {
   MAX_UPLOAD_BYTES: raw.MAX_UPLOAD_MB * 1024 * 1024,
 
   isProduction: raw.NODE_ENV === 'production',
+
+  /** Reminders need a host and a sender; everything else has a default. */
+  isMailConfigured: Boolean(raw.SMTP_HOST && raw.SMTP_FROM),
 } as const;
 
 export type Env = typeof env;

src/lib/collector-colors.ts

@@ -0,0 +1,40 @@
+/**
+ * The small colour palette that tells collectors apart.
+ *
+ * Fixed classes rather than computed ones, because Tailwind only ships the
+ * classes it can see in the source.
+ */
+export const COLLECTOR_COLOR_LABELS: Record<string, string> = {
+  blue: 'Blau',
+  green: 'Grün',
+  amber: 'Gelb',
+  rose: 'Rot',
+  violet: 'Violett',
+  slate: 'Grau',
+};
+
+const BADGE_CLASSES: Record<string, string> = {
+  blue: 'bg-blue-100 text-blue-900 dark:bg-blue-950 dark:text-blue-200',
+  green: 'bg-emerald-100 text-emerald-900 dark:bg-emerald-950 dark:text-emerald-200',
+  amber: 'bg-amber-100 text-amber-900 dark:bg-amber-950 dark:text-amber-200',
+  rose: 'bg-rose-100 text-rose-900 dark:bg-rose-950 dark:text-rose-200',
+  violet: 'bg-violet-100 text-violet-900 dark:bg-violet-950 dark:text-violet-200',
+  slate: 'bg-slate-200 text-slate-900 dark:bg-slate-800 dark:text-slate-100',
+};
+
+export function collectorBadgeClass(color: string | null | undefined): string {
+  return BADGE_CLASSES[color ?? 'blue'] ?? BADGE_CLASSES.blue!;
+}
+
+const DOT_CLASSES: Record<string, string> = {
+  blue: 'bg-blue-500',
+  green: 'bg-emerald-500',
+  amber: 'bg-amber-500',
+  rose: 'bg-rose-500',
+  violet: 'bg-violet-500',
+  slate: 'bg-slate-500',
+};
+
+export function collectorDotClass(color: string | null | undefined): string {
+  return DOT_CLASSES[color ?? 'blue'] ?? DOT_CLASSES.blue!;
+}

src/lib/mailer.ts

@@ -0,0 +1,77 @@
+import 'server-only';
+import nodemailer, { type Transporter } from 'nodemailer';
+import { env } from '@/env';
+
+/**
+ * Outgoing mail.
+ *
+ * Entirely optional: without SMTP_HOST and SMTP_FROM nothing is scheduled and
+ * nothing is sent. The app never depends on mail working.
+ */
+
+let transporter: Transporter | null = null;
+
+function getTransporter(): Transporter | null {
+  if (!env.isMailConfigured) return null;
+  if (transporter) return transporter;
+
+  transporter = nodemailer.createTransport({
+    host: env.SMTP_HOST,
+    port: env.SMTP_PORT,
+    // Implicit TLS on 465, STARTTLS on 587 - the usual pair.
+    secure: env.SMTP_SECURE || env.SMTP_PORT === 465,
+    auth:
+      env.SMTP_USER && env.SMTP_PASSWORD
+        ? { user: env.SMTP_USER, pass: env.SMTP_PASSWORD }
+        : undefined,
+  });
+
+  return transporter;
+}
+
+export type MailResult = { ok: true } | { ok: false; error: string };
+
+export async function sendMail(input: {
+  to: string;
+  subject: string;
+  text: string;
+}): Promise<MailResult> {
+  const transport = getTransporter();
+  if (!transport) {
+    return { ok: false, error: 'Es ist kein SMTP-Server konfiguriert.' };
+  }
+
+  try {
+    await transport.sendMail({
+      from: env.SMTP_FROM,
+      to: input.to,
+      subject: input.subject,
+      text: input.text,
+    });
+    return { ok: true };
+  } catch (error) {
+    console.error('[mail] Versand fehlgeschlagen', error);
+    return {
+      ok: false,
+      error: error instanceof Error ? error.message : 'Der Versand ist fehlgeschlagen.',
+    };
+  }
+}
+
+/** Checks the connection without sending anything. */
+export async function verifyMailConnection(): Promise<MailResult> {
+  const transport = getTransporter();
+  if (!transport) {
+    return { ok: false, error: 'Es ist kein SMTP-Server konfiguriert.' };
+  }
+
+  try {
+    await transport.verify();
+    return { ok: true };
+  } catch (error) {
+    return {
+      ok: false,
+      error: error instanceof Error ? error.message : 'Der Server antwortet nicht.',
+    };
+  }
+}

src/lib/ownership.ts

@@ -8,8 +8,9 @@ import type { CollectionStatus } from '@/db/types';
  * status is anything but `sold`. A sold copy is history, not ownership - so a
  * set that was sold shows up under "fehlt" again and can go back on a wishlist.
  *
- * Every query that asks about ownership goes through this module. If the rule
- * ever changes, it changes here.
+ * With more than one collector the question gains a "for whom": the catalog is
+ * shared, ownership is not. Every query that asks about ownership goes through
+ * this module, optionally scoped to one collector.
  */
 
 export const OWNED_STATUSES = ['owned', 'built', 'disassembled', 'lent_out'] as const;
@@ -18,6 +19,12 @@ export const SOLD_STATUS: CollectionStatus = 'sold';
 
 export type OwnedStatus = (typeof OWNED_STATUSES)[number];
 
+/** One owned copy, as far as ownership is concerned. */
+export type OwnableCopy = {
+  status: CollectionStatus;
+  collectorId?: string | null;
+};
+
 /** Does a single collection item count towards ownership? */
 export function isOwningStatus(status: CollectionStatus): status is OwnedStatus {
   return status !== SOLD_STATUS;
@@ -37,25 +44,75 @@ export function countOwnedCopies(statuses: readonly CollectionStatus[]): number
 }
 
 /**
- * SQL counterpart of `countOwnedCopies`, as a correlated subquery.
+ * Ownership from the point of view of one collector.
+ *
+ * Without a collector the question is "does anyone here have it", which is
+ * what a single-collector household asks anyway.
+ */
+export function countOwnedCopiesFor(
+  copies: readonly OwnableCopy[],
+  collectorId?: string | null,
+): number {
+  return copies.filter(
+    (copy) =>
+      isOwningStatus(copy.status) &&
+      (collectorId === undefined || collectorId === null || copy.collectorId === collectorId),
+  ).length;
+}
+
+export function isSetOwnedBy(
+  copies: readonly OwnableCopy[],
+  collectorId?: string | null,
+): boolean {
+  return countOwnedCopiesFor(copies, collectorId) > 0;
+}
+
+/**
+ * SQL counterpart of `countOwnedCopiesFor`, as a correlated subquery.
  *
  * A subquery instead of a join, because a set owned twice must not appear
  * twice in the catalog list.
  */
-export function ownedCopiesSql(setIdColumn: SQL | unknown): SQL<number> {
+export function ownedCopiesSql(
+  setIdColumn: SQL | unknown,
+  collectorId?: string | null,
+): SQL<number> {
+  if (!collectorId) {
     return sql<number>`(
       select count(*) from collection_item ci
       where ci.set_id = ${setIdColumn} and ci.status <> ${SOLD_STATUS}
     )`;
   }
 
-/** How many wishlists this set is currently on. */
-export function wishlistCountSql(setIdColumn: SQL | unknown): SQL<number> {
+  return sql<number>`(
+    select count(*) from collection_item ci
+    where ci.set_id = ${setIdColumn}
+      and ci.status <> ${SOLD_STATUS}
+      and ci.collector_id = ${collectorId}
+  )`;
+}
+
+/**
+ * How many wishlists this set is on. Scoped to a collector where one is
+ * selected - a set on the other child's list is not "already wished for" here.
+ */
+export function wishlistCountSql(
+  setIdColumn: SQL | unknown,
+  collectorId?: string | null,
+): SQL<number> {
+  if (!collectorId) {
     return sql<number>`(
       select count(*) from wishlist_item wi where wi.set_id = ${setIdColumn}
     )`;
   }
 
+  return sql<number>`(
+    select count(*) from wishlist_item wi
+    join wishlist w on w.id = wi.wishlist_id
+    where wi.set_id = ${setIdColumn} and w.collector_id = ${collectorId}
+  )`;
+}
+
 /** The four states the catalog filter offers, as they appear in the URL. */
 export const OWNERSHIP_FILTERS = ['alle', 'sammlung', 'fehlt', 'wunschliste'] as const;
 

src/lib/prices.ts

@@ -0,0 +1,77 @@
+/**
+ * Value development of a set.
+ *
+ * Pure functions: the interesting logic is "which number counts as the current
+ * value" and "what has changed since", and that should be testable without a
+ * database.
+ */
+
+export type PriceObservation = {
+  priceCents: number;
+  condition: 'new' | 'used';
+  observedAt: Date;
+};
+
+/**
+ * The current value: the most recent observation. Where two land on the same
+ * day, the one for a new set wins - that is the number you would pay to
+ * replace it.
+ */
+export function currentPrice(
+  observations: readonly PriceObservation[],
+  retailPriceCents?: number | null,
+): number | null {
+  if (observations.length === 0) return retailPriceCents ?? null;
+
+  const sorted = [...observations].sort((a, b) => {
+    const byDate = b.observedAt.getTime() - a.observedAt.getTime();
+    if (byDate !== 0) return byDate;
+    return a.condition === 'new' ? -1 : 1;
+  });
+
+  return sorted[0]!.priceCents;
+}
+
+export type PriceTrend = {
+  /** What it cost originally - the UVP, or the oldest observation. */
+  baseCents: number | null;
+  currentCents: number | null;
+  changeCents: number | null;
+  /** Rounded to one decimal, positive means it gained value. */
+  changePercent: number | null;
+};
+
+export function priceTrend(
+  observations: readonly PriceObservation[],
+  retailPriceCents?: number | null,
+): PriceTrend {
+  const current = currentPrice(observations, retailPriceCents);
+
+  const oldest = [...observations].sort(
+    (a, b) => a.observedAt.getTime() - b.observedAt.getTime(),
+  )[0];
+  // The recommended retail price is the honest baseline; only without one do
+  // we fall back to the earliest thing we saw.
+  const base = retailPriceCents ?? oldest?.priceCents ?? null;
+
+  if (base === null || current === null || base === 0) {
+    return { baseCents: base, currentCents: current, changeCents: null, changePercent: null };
+  }
+
+  const changeCents = current - base;
+  return {
+    baseCents: base,
+    currentCents: current,
+    changeCents,
+    changePercent: Math.round((changeCents / base) * 1000) / 10,
+  };
+}
+
+/** Sum of the current value of many sets, ignoring the ones without a price. */
+export function totalValueCents(
+  entries: readonly { observations: readonly PriceObservation[]; retailPriceCents?: number | null }[],
+): number {
+  return entries.reduce((total, entry) => {
+    return total + (currentPrice(entry.observations, entry.retailPriceCents) ?? 0);
+  }, 0);
+}

src/lib/queries/catalog.ts

@@ -1,7 +1,15 @@
 import 'server-only';
 import { and, asc, desc, eq, like, not, or, sql, type SQL } from 'drizzle-orm';
 import { db } from '@/db';
-import { collectionItem, instruction, manufacturer, photo, set, theme } from '@/db/schema';
+import {
+  collectionItem,
+  instruction,
+  manufacturer,
+  photo,
+  pricePoint,
+  set,
+  theme,
+} from '@/db/schema';
 import { ownedCopiesSql, wishlistCountSql, type OwnershipFilter } from '@/lib/ownership';
 
 export const CATALOG_PAGE_SIZE = 48;
@@ -14,6 +22,8 @@ export type CatalogFilters = {
   ownership?: OwnershipFilter;
   /** Hides sets that are already on this wishlist (for "aus fehlenden Sets hinzufügen"). */
   excludeWishlistId?: string;
+  /** Scopes "owned" and "on a wishlist" to one collector. */
+  collectorId?: string;
   page?: number;
 };
 
@@ -52,7 +62,7 @@ function buildWhere(filters: CatalogFilters): SQL | undefined {
   if (filters.themeId) conditions.push(eq(set.themeId, filters.themeId));
   if (filters.year !== undefined) conditions.push(eq(set.year, filters.year));
 
-  const owned = ownedCopiesSql(set.id);
+  const owned = ownedCopiesSql(set.id, filters.collectorId);
   switch (filters.ownership) {
     case 'sammlung':
       conditions.push(sql`${owned} > 0`);
@@ -61,7 +71,7 @@ function buildWhere(filters: CatalogFilters): SQL | undefined {
       conditions.push(sql`${owned} = 0`);
       break;
     case 'wunschliste':
-      conditions.push(sql`${wishlistCountSql(set.id)} > 0`);
+      conditions.push(sql`${wishlistCountSql(set.id, filters.collectorId)} > 0`);
       break;
     default:
       break;
@@ -95,8 +105,8 @@ export function listSets(filters: CatalogFilters): { rows: CatalogRow[]; total:
       retailPriceCents: set.retailPriceCents,
       manufacturerName: manufacturer.name,
       themeName: theme.name,
-      ownedCopies: ownedCopiesSql(set.id).mapWith(Number),
-      wishlistCount: wishlistCountSql(set.id).mapWith(Number),
+      ownedCopies: ownedCopiesSql(set.id, filters.collectorId).mapWith(Number),
+      wishlistCount: wishlistCountSql(set.id, filters.collectorId).mapWith(Number),
     })
     .from(set)
     .innerJoin(manufacturer, eq(manufacturer.id, set.manufacturerId))
@@ -126,7 +136,7 @@ export function listSetIds(filters: CatalogFilters): string[] {
     .map((row) => row.id);
 }
 
-export function getSetById(id: string) {
+export function getSetById(id: string, collectorId?: string) {
   const row = db
     .select({
       id: set.id,
@@ -148,8 +158,8 @@ export function getSetById(id: string) {
       notes: set.notes,
       createdAt: set.createdAt,
       updatedAt: set.updatedAt,
-      ownedCopies: ownedCopiesSql(set.id).mapWith(Number),
-      wishlistCount: wishlistCountSql(set.id).mapWith(Number),
+      ownedCopies: ownedCopiesSql(set.id, collectorId).mapWith(Number),
+      wishlistCount: wishlistCountSql(set.id, collectorId).mapWith(Number),
     })
     .from(set)
     .innerJoin(manufacturer, eq(manufacturer.id, set.manufacturerId))
@@ -225,3 +235,28 @@ export function listSetYears(): number[] {
     .all()
     .flatMap((row) => (row.year === null ? [] : [row.year]));
 }
+
+export type PricePointRow = {
+  id: string;
+  priceCents: number;
+  condition: 'new' | 'used';
+  source: string | null;
+  observedAt: Date;
+  note: string | null;
+};
+
+export function listPricePoints(setId: string): PricePointRow[] {
+  return db
+    .select({
+      id: pricePoint.id,
+      priceCents: pricePoint.priceCents,
+      condition: pricePoint.condition,
+      source: pricePoint.source,
+      observedAt: pricePoint.observedAt,
+      note: pricePoint.note,
+    })
+    .from(pricePoint)
+    .where(eq(pricePoint.setId, setId))
+    .orderBy(desc(pricePoint.observedAt))
+    .all();
+}

src/lib/queries/collection.ts

@@ -1,8 +1,16 @@
 import 'server-only';
 import { and, asc, countDistinct, eq, inArray, sql, type SQL } from 'drizzle-orm';
 import { db } from '@/db';
-import { collectionItem, location, manufacturer, missingPart, set, theme } from '@/db/schema';
-import { SOLD_STATUS } from '@/lib/ownership';
+import {
+  collectionItem,
+  collector,
+  location,
+  manufacturer,
+  missingPart,
+  set,
+  theme,
+} from '@/db/schema';
+import { ownedCopiesSql, SOLD_STATUS } from '@/lib/ownership';
 import type { CollectionStatus, Completeness, Condition } from '@/db/types';
 
 export type CollectionFilters = {
@@ -11,6 +19,7 @@ export type CollectionFilters = {
   completeness?: Completeness;
   locationId?: string;
   manufacturerId?: string;
+  collectorId?: string;
 };
 
 export type CollectionRow = {
@@ -21,6 +30,9 @@ export type CollectionRow = {
   condition: Condition | null;
   locationId: string | null;
   locationName: string | null;
+  collectorId: string | null;
+  collectorName: string | null;
+  collectorColor: string | null;
   acquiredAt: Date | null;
   acquiredPriceCents: number | null;
   acquiredFrom: string | null;
@@ -51,6 +63,7 @@ function buildWhere(filters: CollectionFilters): SQL | undefined {
   if (filters.completeness) conditions.push(eq(collectionItem.completeness, filters.completeness));
   if (filters.locationId) conditions.push(eq(collectionItem.locationId, filters.locationId));
   if (filters.manufacturerId) conditions.push(eq(set.manufacturerId, filters.manufacturerId));
+  if (filters.collectorId) conditions.push(eq(collectionItem.collectorId, filters.collectorId));
 
   return conditions.length > 0 ? and(...conditions) : undefined;
 }
@@ -65,6 +78,9 @@ export function listCollectionItems(filters: CollectionFilters): CollectionRow[]
       condition: collectionItem.condition,
       locationId: collectionItem.locationId,
       locationName: location.name,
+      collectorId: collectionItem.collectorId,
+      collectorName: collector.name,
+      collectorColor: collector.color,
       acquiredAt: collectionItem.acquiredAt,
       acquiredPriceCents: collectionItem.acquiredPriceCents,
       acquiredFrom: collectionItem.acquiredFrom,
@@ -86,6 +102,7 @@ export function listCollectionItems(filters: CollectionFilters): CollectionRow[]
     .innerJoin(manufacturer, eq(manufacturer.id, set.manufacturerId))
     .leftJoin(theme, eq(theme.id, set.themeId))
     .leftJoin(location, eq(location.id, collectionItem.locationId))
+    .leftJoin(collector, eq(collector.id, collectionItem.collectorId))
     .where(buildWhere(filters))
     .orderBy(asc(manufacturer.name), asc(set.setNumber))
     .all();
@@ -96,6 +113,8 @@ export type CollectionStats = {
   itemCount: number;
   pieceCount: number;
   retailValueCents: number;
+  /** Latest observed price where there is one, UVP otherwise. */
+  currentValueCents: number;
   paidCents: number;
   byManufacturer: Array<{ name: string; count: number }>;
 };
@@ -104,8 +123,13 @@ export type CollectionStats = {
  * The numbers on top of the collection page. Sold copies are history and do
  * not count anywhere - same rule as everywhere else in the app.
  */
-export function getCollectionStats(): CollectionStats {
-  const active = sql`${collectionItem.status} <> ${SOLD_STATUS}`;
+export function getCollectionStats(collectorId?: string): CollectionStats {
+  const active = collectorId
+    ? and(
+        sql`${collectionItem.status} <> ${SOLD_STATUS}`,
+        eq(collectionItem.collectorId, collectorId),
+      )
+    : sql`${collectionItem.status} <> ${SOLD_STATUS}`;
 
   const [totals] = db
     .select({
@@ -133,27 +157,39 @@ export function getCollectionStats(): CollectionStats {
     .orderBy(asc(manufacturer.name))
     .all();
 
+  // Current value per copy: the newest observed price, falling back to the
+  // recommended retail price of the set.
+  const [current] = db
+    .select({
+      total: sql<number>`coalesce(sum(coalesce((
+        select p.price_cents from price_point p
+        where p.set_id = ${set.id}
+        order by p.observed_at desc, p.created_at desc
+        limit 1
+      ), ${set.retailPriceCents}, 0)), 0)`.mapWith(Number),
+    })
+    .from(collectionItem)
+    .innerJoin(set, eq(set.id, collectionItem.setId))
+    .where(active)
+    .all();
+
   return {
     setCount: totals?.setCount ?? 0,
     itemCount: totals?.itemCount ?? 0,
     pieceCount: totals?.pieceCount ?? 0,
     retailValueCents: totals?.retailValueCents ?? 0,
+    currentValueCents: current?.total ?? 0,
     paidCents: totals?.paidCents ?? 0,
     byManufacturer,
   };
 }
 
 /** Number of catalog sets that are not in the collection - the "fehlt" count. */
-export function countMissingSets(): number {
+export function countMissingSets(collectorId?: string): number {
   const [row] = db
     .select({ total: sql<number>`count(*)`.mapWith(Number) })
     .from(set)
-    .where(
-      sql`not exists (
-        select 1 from collection_item ci
-        where ci.set_id = ${set.id} and ci.status <> ${SOLD_STATUS}
-      )`,
-    )
+    .where(sql`${ownedCopiesSql(set.id, collectorId)} = 0`)
     .all();
 
   return row?.total ?? 0;

src/lib/queries/collectors.ts

@@ -0,0 +1,89 @@
+import 'server-only';
+import { asc, eq, sql } from 'drizzle-orm';
+import { db } from '@/db';
+import { collectionItem, collector } from '@/db/schema';
+import { SOLD_STATUS } from '@/lib/ownership';
+
+export type CollectorRow = {
+  id: string;
+  name: string;
+  color: string;
+  birthday: Date | null;
+  notes: string | null;
+  sortOrder: number;
+  itemCount: number;
+};
+
+export function listCollectors(): CollectorRow[] {
+  const itemCount = sql<number>`(
+    select count(*) from collection_item ci
+    where ci.collector_id = ${collector.id} and ci.status <> ${SOLD_STATUS}
+  )`.mapWith(Number);
+
+  return db
+    .select({
+      id: collector.id,
+      name: collector.name,
+      color: collector.color,
+      birthday: collector.birthday,
+      notes: collector.notes,
+      sortOrder: collector.sortOrder,
+      itemCount,
+    })
+    .from(collector)
+    .orderBy(asc(collector.sortOrder), asc(collector.name))
+    .all();
+}
+
+export function getCollector(id: string) {
+  return db.select().from(collector).where(eq(collector.id, id)).get() ?? null;
+}
+
+/**
+ * The collector a new collection item belongs to when the user did not pick
+ * one - which is every time there is only a single collector.
+ */
+export function defaultCollectorId(): string | null {
+  const row = db
+    .select({ id: collector.id })
+    .from(collector)
+    .orderBy(asc(collector.sortOrder), asc(collector.name))
+    .get();
+  return row?.id ?? null;
+}
+
+/**
+ * The whole multi-collector idea only becomes visible once a second collector
+ * exists. Until then the UI stays exactly as simple as it was.
+ */
+export function hasMultipleCollectors(): boolean {
+  const [row] = db
+    .select({ total: sql<number>`count(*)`.mapWith(Number) })
+    .from(collector)
+    .all();
+  return (row?.total ?? 0) > 1;
+}
+
+/** Reads the collector from a URL parameter, ignoring anything unknown. */
+export function resolveCollectorId(value: string | undefined | null): string | undefined {
+  if (!value) return undefined;
+  const row = db.select({ id: collector.id }).from(collector).where(eq(collector.id, value)).get();
+  return row?.id;
+}
+
+/** Owned copies per collector - used by the collector management page. */
+export function countItemsPerCollector(): Map<string, number> {
+  const rows = db
+    .select({
+      collectorId: collectionItem.collectorId,
+      total: sql<number>`count(*)`.mapWith(Number),
+    })
+    .from(collectionItem)
+    .where(sql`${collectionItem.status} <> ${SOLD_STATUS}`)
+    .groupBy(collectionItem.collectorId)
+    .all();
+
+  return new Map(
+    rows.flatMap((row) => (row.collectorId ? [[row.collectorId, row.total] as const] : [])),
+  );
+}

src/lib/queries/wishlists.ts

@@ -1,8 +1,8 @@
 import 'server-only';
 import { and, asc, count, eq, inArray, isNotNull, isNull, sql } from 'drizzle-orm';
 import { db } from '@/db';
-import { manufacturer, set, theme, wishlist, wishlistItem } from '@/db/schema';
-import { ownedCopiesSql } from '@/lib/ownership';
+import { collector, manufacturer, set, theme, wishlist, wishlistItem } from '@/db/schema';
+import { ownedCopiesSql, SOLD_STATUS } from '@/lib/ownership';
 
 /** Short list for the "auf welche Wunschliste?" dialogs. */
 export function listWishlistTargets() {
@@ -34,12 +34,16 @@ export function listWishlists(ownerUserId: string) {
       isPublic: wishlist.isPublic,
       surpriseMode: wishlist.surpriseMode,
       shareToken: wishlist.shareToken,
+      collectorId: wishlist.collectorId,
+      collectorName: collector.name,
+      collectorColor: collector.color,
       createdAt: wishlist.createdAt,
       itemCount: count(wishlistItem.id),
       openCount: openItems,
     })
     .from(wishlist)
     .leftJoin(wishlistItem, eq(wishlistItem.wishlistId, wishlist.id))
+    .leftJoin(collector, eq(collector.id, wishlist.collectorId))
     .where(eq(wishlist.ownerUserId, ownerUserId))
     .groupBy(wishlist.id)
     .orderBy(asc(wishlist.title))
@@ -76,7 +80,10 @@ export type WishlistItemRow = {
   ownedCopies: number;
 };
 
-export function listWishlistItems(wishlistId: string): WishlistItemRow[] {
+export function listWishlistItems(
+  wishlistId: string,
+  collectorId?: string | null,
+): WishlistItemRow[] {
   return db
     .select({
       id: wishlistItem.id,
@@ -97,7 +104,7 @@ export function listWishlistItems(wishlistId: string): WishlistItemRow[] {
       manufacturerName: manufacturer.name,
       manufacturerWebsite: manufacturer.website,
       themeName: theme.name,
-      ownedCopies: ownedCopiesSql(set.id).mapWith(Number),
+      ownedCopies: ownedCopiesSql(set.id, collectorId).mapWith(Number),
     })
     .from(wishlistItem)
     .innerJoin(set, eq(set.id, wishlistItem.setId))
@@ -145,17 +152,28 @@ export function listWishlistsForSet(setId: string) {
  * Marks wishlist entries as fulfilled once the set is in the collection, and
  * clears the flag again if the copy was sold. Called after every change to the
  * collection, so the lists stay honest without a background job.
+ *
+ * With several collectors the question is per list: a wish on Max's list is
+ * fulfilled when *Max* owns the set, not when his sister does. A list without
+ * a collector falls back to "anyone here owns it".
  */
 export function reconcileFulfilledWishlistItems(): void {
-  const owned = ownedCopiesSql(wishlistItem.setId);
+  const ownedForThisList = sql`exists (
+    select 1
+    from collection_item ci
+    join wishlist w on w.id = ${wishlistItem.wishlistId}
+    where ci.set_id = ${wishlistItem.setId}
+      and ci.status <> ${SOLD_STATUS}
+      and (w.collector_id is null or ci.collector_id = w.collector_id)
+  )`;
 
   db.update(wishlistItem)
     .set({ fulfilledAt: new Date() })
-    .where(and(isNull(wishlistItem.fulfilledAt), sql`${owned} > 0`))
+    .where(and(isNull(wishlistItem.fulfilledAt), ownedForThisList))
     .run();
 
   db.update(wishlistItem)
     .set({ fulfilledAt: null })
-    .where(and(isNotNull(wishlistItem.fulfilledAt), sql`${owned} = 0`))
+    .where(and(isNotNull(wishlistItem.fulfilledAt), sql`not ${ownedForThisList}`))
     .run();
 }

src/lib/reminder-job.ts

@@ -0,0 +1,156 @@
+import 'server-only';
+import { eq, sql } from 'drizzle-orm';
+import { db } from '@/db';
+import { user, wishlist } from '@/db/schema';
+import { env } from '@/env';
+import { sendMail } from './mailer';
+import {
+  reminderSubject,
+  reminderText,
+  shouldRemind,
+  type RemindableWishlist,
+} from './reminders';
+
+/**
+ * Sends the due wishlist reminders.
+ *
+ * Run from the hourly scheduler and from the "jetzt prüfen" button. Sending is
+ * recorded on the list, so a second run within the week stays quiet.
+ */
+
+export type ReminderRun = {
+  checked: number;
+  sent: number;
+  skipped: number;
+  failures: Array<{ title: string; error: string }>;
+};
+
+type Candidate = RemindableWishlist & {
+  ownerEmail: string;
+  ownerName: string;
+  shareToken: string;
+  isPublic: boolean;
+};
+
+function loadCandidates(): Candidate[] {
+  const openItems = sql<number>`(
+    select count(*) from wishlist_item wi
+    where wi.wishlist_id = ${wishlist.id}
+      and wi.reserved_at is null
+      and wi.fulfilled_at is null
+  )`.mapWith(Number);
+
+  return db
+    .select({
+      id: wishlist.id,
+      title: wishlist.title,
+      eventDate: wishlist.eventDate,
+      lastReminderAt: wishlist.lastReminderAt,
+      shareToken: wishlist.shareToken,
+      isPublic: wishlist.isPublic,
+      ownerEmail: user.email,
+      ownerName: user.name,
+      openItemCount: openItems,
+    })
+    .from(wishlist)
+    .innerJoin(user, eq(user.id, wishlist.ownerUserId))
+    .all();
+}
+
+export async function runReminderJob(now = new Date()): Promise<ReminderRun> {
+  const result: ReminderRun = { checked: 0, sent: 0, skipped: 0, failures: [] };
+  if (!env.isMailConfigured) return result;
+
+  const candidates = loadCandidates();
+  result.checked = candidates.length;
+
+  for (const candidate of candidates) {
+    const decision = shouldRemind(candidate, {
+      now,
+      daysBefore: env.REMINDER_DAYS_BEFORE,
+    });
+
+    if (!decision.remind) {
+      result.skipped += 1;
+      continue;
+    }
+
+    const mail = await sendMail({
+      to: candidate.ownerEmail,
+      subject: reminderSubject(candidate, decision.daysLeft),
+      text: reminderText({
+        title: candidate.title,
+        daysLeft: decision.daysLeft,
+        openItemCount: candidate.openItemCount,
+        shareUrl: candidate.isPublic
+          ? `${env.BASE_URL}/w/${candidate.shareToken}`
+          : '(Teilen ist für diese Liste ausgeschaltet)',
+        appUrl: `${env.BASE_URL}/wunschlisten/${candidate.id}`,
+      }),
+    });
+
+    if (!mail.ok) {
+      result.failures.push({ title: candidate.title, error: mail.error });
+      continue;
+    }
+
+    // Only after a successful send - a failed attempt must be retried.
+    db.update(wishlist)
+      .set({ lastReminderAt: now })
+      .where(eq(wishlist.id, candidate.id))
+      .run();
+    result.sent += 1;
+  }
+
+  return result;
+}
+
+const HOUR_MS = 60 * 60 * 1000;
+
+/**
+ * Started lazily from the first server render or healthcheck rather than from
+ * Next's instrumentation hook: that hook is compiled for the edge runtime too,
+ * and pulling the native SQLite driver into that bundle breaks the build.
+ * Cached on globalThis so the dev server's module reloading cannot stack up
+ * several schedulers.
+ */
+const globalForScheduler = globalThis as unknown as { bricktrackReminders?: boolean };
+
+export function ensureReminderScheduler(): void {
+  if (globalForScheduler.bricktrackReminders) return;
+  globalForScheduler.bricktrackReminders = true;
+  startReminderScheduler();
+}
+
+/**
+ * Starts the hourly check.
+ *
+ * Hourly rather than daily so a restart cannot skip a day, and the per-list
+ * cooldown keeps that from turning into repeated mail.
+ */
+export function startReminderScheduler(): void {
+  if (!env.isMailConfigured) {
+    console.log('[reminders] Kein SMTP konfiguriert - Erinnerungen sind aus.');
+    return;
+  }
+
+  console.log(
+    `[reminders] Aktiv: Erinnerung ${env.REMINDER_DAYS_BEFORE} Tage vor dem Termin, stuendliche Pruefung.`,
+  );
+
+  const tick = () => {
+    void runReminderJob()
+      .then((run) => {
+        if (run.sent > 0 || run.failures.length > 0) {
+          console.log(
+            `[reminders] ${run.sent} verschickt, ${run.failures.length} fehlgeschlagen.`,
+          );
+        }
+      })
+      .catch((error) => console.error('[reminders] Durchlauf fehlgeschlagen', error));
+  };
+
+  // A short delay so the first check does not compete with the app's start-up.
+  setTimeout(tick, 60_000).unref?.();
+  setInterval(tick, HOUR_MS).unref?.();
+}

src/lib/reminders.ts

@@ -0,0 +1,91 @@
+/**
+ * When to remind someone about a wishlist.
+ *
+ * Pure rules, no database and no mail: a reminder that arrives at the wrong
+ * moment is worse than none, so this is the part that gets tested.
+ */
+
+export type RemindableWishlist = {
+  id: string;
+  title: string;
+  eventDate: Date | null;
+  openItemCount: number;
+  lastReminderAt: Date | null;
+};
+
+export type ReminderDecision =
+  | { remind: true; daysLeft: number }
+  | { remind: false; reason: 'no-date' | 'too-early' | 'past' | 'nothing-open' | 'already-sent' };
+
+/** Whole days between two points, ignoring the time of day. */
+export function daysUntil(target: Date, now: Date): number {
+  const startOfTarget = Date.UTC(target.getFullYear(), target.getMonth(), target.getDate());
+  const startOfNow = Date.UTC(now.getFullYear(), now.getMonth(), now.getDate());
+  return Math.round((startOfTarget - startOfNow) / 86_400_000);
+}
+
+/**
+ * A reminder goes out when the date is close, something is still unclaimed,
+ * and we have not just written about it.
+ */
+export function shouldRemind(
+  list: RemindableWishlist,
+  options: { now: Date; daysBefore: number; minDaysBetween?: number },
+): ReminderDecision {
+  const minDaysBetween = options.minDaysBetween ?? 7;
+
+  if (!list.eventDate) return { remind: false, reason: 'no-date' };
+
+  const daysLeft = daysUntil(list.eventDate, options.now);
+  // The day itself still counts - a morning reminder can save the afternoon.
+  if (daysLeft < 0) return { remind: false, reason: 'past' };
+  if (daysLeft > options.daysBefore) return { remind: false, reason: 'too-early' };
+
+  // Nothing open means everything is taken care of; silence is the right answer.
+  if (list.openItemCount <= 0) return { remind: false, reason: 'nothing-open' };
+
+  if (list.lastReminderAt) {
+    // daysUntil(now, lastReminderAt) reads as "days from the last reminder
+    // until now", which is exactly the age of that reminder.
+    const daysSinceLast = daysUntil(options.now, list.lastReminderAt);
+    if (daysSinceLast < minDaysBetween) return { remind: false, reason: 'already-sent' };
+  }
+
+  return { remind: true, daysLeft };
+}
+
+/** German subject line, because that is what lands in the inbox. */
+export function reminderSubject(list: RemindableWishlist, daysLeft: number): string {
+  if (daysLeft === 0) return `Heute: ${list.title}`;
+  if (daysLeft === 1) return `Morgen: ${list.title}`;
+  return `In ${daysLeft} Tagen: ${list.title}`;
+}
+
+export function reminderText(input: {
+  title: string;
+  daysLeft: number;
+  openItemCount: number;
+  shareUrl: string;
+  appUrl: string;
+}): string {
+  const when =
+    input.daysLeft === 0
+      ? 'ist heute'
+      : input.daysLeft === 1
+        ? 'ist morgen'
+        : `ist in ${input.daysLeft} Tagen`;
+
+  const open =
+    input.openItemCount === 1
+      ? 'steht noch 1 Wunsch offen'
+      : `stehen noch ${input.openItemCount} Wünsche offen`;
+
+  return [
+    `Der Termin für „${input.title}" ${when}, und auf der Liste ${open}.`,
+    '',
+    `Liste ansehen:  ${input.appUrl}`,
+    `Zum Teilen:     ${input.shareUrl}`,
+    '',
+    'Diese Erinnerung kommt von deinem eigenen Bricktrack.',
+  ].join('\n');
+}

src/lib/similarity.ts

@@ -0,0 +1,77 @@
+/**
+ * Name comparison for the duplicate check when a set is created.
+ *
+ * Pure and free of server imports so it can be unit tested - and it needs to
+ * be, because "similar enough" is a judgement call that is easy to get wrong
+ * in both directions.
+ */
+
+/**
+ * Lowercases, strips punctuation and collapses whitespace, so that
+ * "Feuerwehr-Auto" and "feuerwehr auto" are the same string.
+ */
+export function normalizeName(value: string): string {
+  return value
+    .toLowerCase()
+    .replace(/ä/g, 'ae')
+    .replace(/ö/g, 'oe')
+    .replace(/ü/g, 'ue')
+    .replace(/ß/g, 'ss')
+    .replace(/[^a-z0-9]+/g, ' ')
+    .trim();
+}
+
+/** Classic Levenshtein distance, iterative with a single row. */
+export function levenshtein(a: string, b: string): number {
+  if (a === b) return 0;
+  if (a.length === 0) return b.length;
+  if (b.length === 0) return a.length;
+
+  let previous = Array.from({ length: b.length + 1 }, (_, index) => index);
+
+  for (let i = 1; i <= a.length; i += 1) {
+    const current = [i];
+    for (let j = 1; j <= b.length; j += 1) {
+      const cost = a[i - 1] === b[j - 1] ? 0 : 1;
+      current[j] = Math.min(
+        current[j - 1]! + 1, // insertion
+        previous[j]! + 1, // deletion
+        previous[j - 1]! + cost, // substitution
+      );
+    }
+    previous = current;
+  }
+
+  return previous[b.length]!;
+}
+
+/** 1 means identical, 0 means nothing in common. */
+export function similarity(a: string, b: string): number {
+  const left = normalizeName(a);
+  const right = normalizeName(b);
+  if (left === right) return 1;
+  if (left.length === 0 || right.length === 0) return 0;
+
+  const longest = Math.max(left.length, right.length);
+  return 1 - levenshtein(left, right) / longest;
+}
+
+/**
+ * Above this, two names are close enough to be worth asking about. Chosen so
+ * that a typo or a different spelling triggers, while two genuinely different
+ * sets of the same theme do not.
+ */
+export const SIMILAR_NAME_THRESHOLD = 0.82;
+
+export function isSimilarName(a: string, b: string): boolean {
+  const left = normalizeName(a);
+  const right = normalizeName(b);
+
+  // One name fully contained in the other ("Feuerwehrauto" vs "Feuerwehrauto
+  // mit Leiter") is a strong hint even when the length differs a lot.
+  if (left.length >= 6 && right.length >= 6 && (left.includes(right) || right.includes(left))) {
+    return true;
+  }
+
+  return similarity(a, b) >= SIMILAR_NAME_THRESHOLD;
+}

src/lib/validation.ts

@@ -88,6 +88,22 @@ export const locationSchema = z.object({
   parentLocationId: optionalId,
 });
 
+export const collectorColorEnum = z.enum([
+  'blue',
+  'green',
+  'amber',
+  'rose',
+  'violet',
+  'slate',
+]);
+
+export const collectorSchema = z.object({
+  name: z.string().trim().min(1, 'Bitte einen Namen angeben.').max(60),
+  color: collectorColorEnum.default('blue'),
+  birthday: optionalDate,
+  notes: optionalText(500),
+});
+
 // ---------------------------------------------------------------------------
 // Catalog
 // ---------------------------------------------------------------------------
@@ -127,6 +143,7 @@ export const conditionEnum = z.enum(['new_sealed', 'like_new', 'good', 'used', '
 
 export const collectionItemSchema = z.object({
   setId: z.string().trim().min(1),
+  collectorId: optionalId,
   status: collectionStatusEnum.default('owned'),
   completeness: completenessEnum.default('unknown'),
   condition: z
@@ -171,6 +188,7 @@ export const occasionEnum = z.enum(['christmas', 'birthday', 'easter', 'other'])
 
 export const wishlistSchema = z.object({
   title: z.string().trim().min(1, 'Bitte einen Titel angeben.').max(80),
+  collectorId: optionalId,
   occasion: occasionEnum.default('other'),
   eventDate: optionalDate,
   note: optionalText(1000),
@@ -205,3 +223,4 @@ export type LocationInput = z.infer<typeof locationSchema>;
 export type SetInput = z.infer<typeof setSchema>;
 export type CollectionItemInput = z.infer<typeof collectionItemSchema>;
 export type WishlistInput = z.infer<typeof wishlistSchema>;
+export type CollectorInput = z.infer<typeof collectorSchema>;

tests/unit/ownership.test.ts

@@ -2,8 +2,10 @@ import { describe, expect, it } from 'vitest';
 import type { CollectionStatus } from '@/db/types';
 import {
   countOwnedCopies,
+  countOwnedCopiesFor,
   isOwningStatus,
   isSetOwned,
+  isSetOwnedBy,
   OWNED_STATUSES,
   parseOwnershipFilter,
 } from '@/lib/ownership';
@@ -59,3 +61,47 @@ describe('Besitz-Filter aus der URL', () => {
     expect(parseOwnershipFilter('')).toBe('alle');
   });
 });
+
+describe('Besitz je Sammler', () => {
+  const copies = [
+    { status: 'built' as const, collectorId: 'max' },
+    { status: 'owned' as const, collectorId: 'mia' },
+    { status: 'sold' as const, collectorId: 'max' },
+  ];
+
+  it('zaehlt ohne Sammler alles, was irgendjemand hier hat', () => {
+    expect(countOwnedCopiesFor(copies)).toBe(2);
+    expect(isSetOwnedBy(copies)).toBe(true);
+  });
+
+  it('zaehlt mit Sammler nur dessen Exemplare', () => {
+    expect(countOwnedCopiesFor(copies, 'max')).toBe(1);
+    expect(countOwnedCopiesFor(copies, 'mia')).toBe(1);
+  });
+
+  it('sieht ein Set als fehlend, wenn nur das Geschwisterkind es hat', () => {
+    const onlyMia = [{ status: 'built' as const, collectorId: 'mia' }];
+
+    expect(isSetOwnedBy(onlyMia, 'mia')).toBe(true);
+    // Genau der Fall, fuer den es mehrere Sammler gibt.
+    expect(isSetOwnedBy(onlyMia, 'max')).toBe(false);
+  });
+
+  it('ignoriert verkaufte Exemplare auch je Sammler', () => {
+    const sold = [{ status: 'sold' as const, collectorId: 'max' }];
+
+    expect(isSetOwnedBy(sold, 'max')).toBe(false);
+    expect(isSetOwnedBy(sold)).toBe(false);
+  });
+
+  it('behandelt einen unbekannten Sammler als "hat nichts"', () => {
+    expect(countOwnedCopiesFor(copies, 'niemand')).toBe(0);
+  });
+
+  it('kommt mit Exemplaren ohne Sammler klar', () => {
+    const unassigned = [{ status: 'owned' as const, collectorId: null }];
+
+    expect(isSetOwnedBy(unassigned)).toBe(true);
+    expect(isSetOwnedBy(unassigned, 'max')).toBe(false);
+  });
+});

tests/unit/prices.test.ts

@@ -0,0 +1,127 @@
+import { describe, expect, it } from 'vitest';
+import { currentPrice, priceTrend, totalValueCents } from '@/lib/prices';
+
+const on = (iso: string) => new Date(`${iso}T12:00:00.000Z`);
+
+describe('Aktueller Wert', () => {
+  it('faellt ohne Beobachtung auf die UVP zurueck', () => {
+    expect(currentPrice([], 4999)).toBe(4999);
+  });
+
+  it('ist null, wenn es weder Beobachtung noch UVP gibt', () => {
+    expect(currentPrice([], null)).toBeNull();
+    expect(currentPrice([])).toBeNull();
+  });
+
+  it('nimmt die neueste Beobachtung, nicht die hoechste', () => {
+    const value = currentPrice(
+      [
+        { priceCents: 9900, condition: 'new', observedAt: on('2026-01-01') },
+        { priceCents: 6900, condition: 'new', observedAt: on('2026-06-01') },
+      ],
+      4999,
+    );
+
+    expect(value).toBe(6900);
+  });
+
+  it('bevorzugt am selben Tag den Neupreis', () => {
+    const value = currentPrice([
+      { priceCents: 4000, condition: 'used', observedAt: on('2026-06-01') },
+      { priceCents: 8000, condition: 'new', observedAt: on('2026-06-01') },
+    ]);
+
+    expect(value).toBe(8000);
+  });
+
+  it('schlaegt die UVP, sobald es eine Beobachtung gibt', () => {
+    const value = currentPrice(
+      [{ priceCents: 12000, condition: 'new', observedAt: on('2026-06-01') }],
+      4999,
+    );
+
+    expect(value).toBe(12000);
+  });
+});
+
+describe('Wertentwicklung', () => {
+  it('misst gegen die UVP', () => {
+    const trend = priceTrend(
+      [{ priceCents: 9998, condition: 'new', observedAt: on('2026-06-01') }],
+      4999,
+    );
+
+    expect(trend.baseCents).toBe(4999);
+    expect(trend.currentCents).toBe(9998);
+    expect(trend.changeCents).toBe(4999);
+    expect(trend.changePercent).toBe(100);
+  });
+
+  it('zeigt auch Verluste', () => {
+    const trend = priceTrend(
+      [{ priceCents: 2500, condition: 'used', observedAt: on('2026-06-01') }],
+      5000,
+    );
+
+    expect(trend.changeCents).toBe(-2500);
+    expect(trend.changePercent).toBe(-50);
+  });
+
+  it('nimmt ohne UVP die aelteste Beobachtung als Basis', () => {
+    const trend = priceTrend([
+      { priceCents: 1000, condition: 'new', observedAt: on('2026-01-01') },
+      { priceCents: 1500, condition: 'new', observedAt: on('2026-06-01') },
+    ]);
+
+    expect(trend.baseCents).toBe(1000);
+    expect(trend.changePercent).toBe(50);
+  });
+
+  it('rechnet nicht, wenn es nichts zu vergleichen gibt', () => {
+    const trend = priceTrend([], null);
+
+    expect(trend.changeCents).toBeNull();
+    expect(trend.changePercent).toBeNull();
+  });
+
+  it('teilt nicht durch null', () => {
+    const trend = priceTrend(
+      [{ priceCents: 1000, condition: 'new', observedAt: on('2026-06-01') }],
+      0,
+    );
+
+    expect(trend.changePercent).toBeNull();
+  });
+
+  it('rundet den Prozentwert auf eine Nachkommastelle', () => {
+    const trend = priceTrend(
+      [{ priceCents: 3333, condition: 'new', observedAt: on('2026-06-01') }],
+      10000,
+    );
+
+    expect(trend.changePercent).toBe(-66.7);
+  });
+});
+
+describe('Gesamtwert', () => {
+  it('summiert die aktuellen Werte', () => {
+    const total = totalValueCents([
+      {
+        observations: [{ priceCents: 6900, condition: 'new', observedAt: on('2026-06-01') }],
+        retailPriceCents: 4999,
+      },
+      { observations: [], retailPriceCents: 2999 },
+    ]);
+
+    expect(total).toBe(9899);
+  });
+
+  it('ignoriert Sets ohne jeden Preis', () => {
+    const total = totalValueCents([
+      { observations: [], retailPriceCents: null },
+      { observations: [], retailPriceCents: 1000 },
+    ]);
+
+    expect(total).toBe(1000);
+  });
+});

tests/unit/reminders.test.ts

@@ -0,0 +1,131 @@
+import { describe, expect, it } from 'vitest';
+import {
+  daysUntil,
+  reminderSubject,
+  reminderText,
+  shouldRemind,
+  type RemindableWishlist,
+} from '@/lib/reminders';
+
+const now = new Date('2026-12-10T09:00:00');
+const on = (iso: string) => new Date(`${iso}T00:00:00`);
+
+function list(overrides: Partial<RemindableWishlist> = {}): RemindableWishlist {
+  return {
+    id: 'w-1',
+    title: 'Weihnachten 2026',
+    eventDate: on('2026-12-24'),
+    openItemCount: 3,
+    lastReminderAt: null,
+    ...overrides,
+  };
+}
+
+describe('Tage bis zum Termin', () => {
+  it('zaehlt ganze Tage, unabhaengig von der Uhrzeit', () => {
+    expect(daysUntil(on('2026-12-24'), now)).toBe(14);
+    expect(daysUntil(on('2026-12-10'), now)).toBe(0);
+    expect(daysUntil(on('2026-12-09'), now)).toBe(-1);
+  });
+});
+
+describe('Wann erinnert wird', () => {
+  it('erinnert, wenn der Termin im Fenster liegt und etwas offen ist', () => {
+    const decision = shouldRemind(list(), { now, daysBefore: 14 });
+
+    expect(decision).toEqual({ remind: true, daysLeft: 14 });
+  });
+
+  it('schweigt, solange der Termin weit weg ist', () => {
+    const decision = shouldRemind(list({ eventDate: on('2027-06-01') }), {
+      now,
+      daysBefore: 14,
+    });
+
+    expect(decision).toEqual({ remind: false, reason: 'too-early' });
+  });
+
+  it('erinnert am Tag selbst noch', () => {
+    const decision = shouldRemind(list({ eventDate: on('2026-12-10') }), {
+      now,
+      daysBefore: 14,
+    });
+
+    expect(decision).toEqual({ remind: true, daysLeft: 0 });
+  });
+
+  it('schweigt, wenn der Termin vorbei ist', () => {
+    const decision = shouldRemind(list({ eventDate: on('2026-12-01') }), {
+      now,
+      daysBefore: 14,
+    });
+
+    expect(decision).toEqual({ remind: false, reason: 'past' });
+  });
+
+  it('schweigt ohne Termin', () => {
+    const decision = shouldRemind(list({ eventDate: null }), { now, daysBefore: 14 });
+
+    expect(decision).toEqual({ remind: false, reason: 'no-date' });
+  });
+
+  it('schweigt, wenn alles reserviert ist', () => {
+    const decision = shouldRemind(list({ openItemCount: 0 }), { now, daysBefore: 14 });
+
+    expect(decision).toEqual({ remind: false, reason: 'nothing-open' });
+  });
+
+  it('wiederholt sich nicht innerhalb einer Woche', () => {
+    const decision = shouldRemind(list({ lastReminderAt: on('2026-12-08') }), {
+      now,
+      daysBefore: 14,
+    });
+
+    expect(decision).toEqual({ remind: false, reason: 'already-sent' });
+  });
+
+  it('erinnert wieder, wenn die Sperrfrist vorbei ist', () => {
+    const decision = shouldRemind(list({ lastReminderAt: on('2026-12-01') }), {
+      now,
+      daysBefore: 14,
+    });
+
+    expect(decision).toMatchObject({ remind: true });
+  });
+});
+
+describe('Betreff und Text', () => {
+  it('formuliert die Naehe im Betreff', () => {
+    expect(reminderSubject(list(), 0)).toBe('Heute: Weihnachten 2026');
+    expect(reminderSubject(list(), 1)).toBe('Morgen: Weihnachten 2026');
+    expect(reminderSubject(list(), 5)).toBe('In 5 Tagen: Weihnachten 2026');
+  });
+
+  it('nennt Termin, offene Wuensche und beide Links', () => {
+    const text = reminderText({
+      title: 'Weihnachten 2026',
+      daysLeft: 3,
+      openItemCount: 2,
+      shareUrl: 'https://bricktrack.example.de/w/abc',
+      appUrl: 'https://bricktrack.example.de/wunschlisten/w-1',
+    });
+
+    expect(text).toContain('ist in 3 Tagen');
+    expect(text).toContain('stehen noch 2 Wünsche offen');
+    expect(text).toContain('https://bricktrack.example.de/w/abc');
+    expect(text).toContain('https://bricktrack.example.de/wunschlisten/w-1');
+  });
+
+  it('bleibt im Singular, wenn nur ein Wunsch offen ist', () => {
+    const text = reminderText({
+      title: 'Geburtstag',
+      daysLeft: 1,
+      openItemCount: 1,
+      shareUrl: 'x',
+      appUrl: 'y',
+    });
+
+    expect(text).toContain('ist morgen');
+    expect(text).toContain('steht noch 1 Wunsch offen');
+  });
+});

tests/unit/similarity.test.ts

@@ -0,0 +1,59 @@
+import { describe, expect, it } from 'vitest';
+import { isSimilarName, levenshtein, normalizeName, similarity } from '@/lib/similarity';
+
+describe('Namen normalisieren', () => {
+  it('schreibt Umlaute aus und wirft Satzzeichen weg', () => {
+    expect(normalizeName('Feuerwehr-Auto')).toBe('feuerwehr auto');
+    expect(normalizeName('Grüne Kiste!')).toBe('gruene kiste');
+    expect(normalizeName('Straßenbahn')).toBe('strassenbahn');
+  });
+
+  it('macht aus mehreren Leerzeichen eines', () => {
+    expect(normalizeName('  Lego   City  ')).toBe('lego city');
+  });
+});
+
+describe('Levenshtein', () => {
+  it('ist null bei identischen Strings', () => {
+    expect(levenshtein('haus', 'haus')).toBe(0);
+  });
+
+  it('zaehlt einzelne Aenderungen', () => {
+    expect(levenshtein('haus', 'maus')).toBe(1);
+    expect(levenshtein('haus', 'hausen')).toBe(2);
+    expect(levenshtein('', 'haus')).toBe(4);
+  });
+});
+
+describe('Aehnlichkeit', () => {
+  it('erkennt identische Namen', () => {
+    expect(similarity('Feuerwehrauto', 'feuerwehrauto')).toBe(1);
+  });
+
+  it('sinkt mit dem Unterschied', () => {
+    expect(similarity('Feuerwehrauto', 'Polizeiauto')).toBeLessThan(0.7);
+  });
+});
+
+describe('Dublettenverdacht', () => {
+  it('schlaegt bei Tippfehlern an', () => {
+    expect(isSimilarName('Familienhaus und Elektroauto', 'Familienhaus und Elektroauo')).toBe(true);
+    expect(isSimilarName('Feuerwehreinsatz', 'Feuerwehr-Einsatz')).toBe(true);
+  });
+
+  it('schlaegt an, wenn ein Name im anderen steckt', () => {
+    expect(isSimilarName('Feuerwehrauto', 'Feuerwehrauto mit Leiter')).toBe(true);
+  });
+
+  it('schlaegt nicht bei verschiedenen Sets desselben Themas an', () => {
+    expect(isSimilarName('Feuerwehreinsatz', 'Polizeistation')).toBe(false);
+    expect(isSimilarName('Kipplaster', 'McLaren P1')).toBe(false);
+    // Zwei echte, unterschiedliche City-Sets.
+    expect(isSimilarName('Familienhaus und Elektroauto', 'Feuerwehreinsatz')).toBe(false);
+  });
+
+  it('laesst sich von kurzen Namen nicht zu Unsinn verleiten', () => {
+    // Ohne die Mindestlaenge wuerde "Bus" in "Autobus" jede Dublette melden.
+    expect(isSimilarName('Bus', 'Autobus')).toBe(false);
+  });
+});