Serialize Flatpak repo publishes to prevent non-fast-forward push failures (#88)

* Initial plan

* Serialize Flatpak repo publish jobs

Co-authored-by: Rsclub22 <37273508+Rsclub22@users.noreply.github.com>

---------

Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>
Co-authored-by: Rsclub22 <37273508+Rsclub22@users.noreply.github.com>

.github/workflows/nightly-artifacts.yml

@@ -551,6 +551,9 @@ jobs:
     name: Publish Flatpak OSTree Repo (nightly)
     runs-on: ubuntu-latest
     needs: build-flatpak
+    concurrency:
+      group: flatpak-repo-publish
+      cancel-in-progress: false
 
     steps:
       - name: Install Flatpak tooling

.github/workflows/tagged-release.yml

@@ -646,6 +646,9 @@ jobs:
     name: Publish Flatpak OSTree Repo (${{ github.ref_name }})
     runs-on: ubuntu-latest
     needs: build-flatpak
+    concurrency:
+      group: flatpak-repo-publish
+      cancel-in-progress: false
 
     steps:
       - name: Install Flatpak tooling

docs/PROJECT_CONTEXT.md

@@ -101,6 +101,16 @@ CR/LF framing, XML framing, ports/transports, callsign normalization and frequen
 - External logger threads do not read or mutate the JavaFX user-list projection. `ChatController` applies global and per-band Worked state to every active variant of the base callsign on the JavaFX Application Thread before evaluating a band-upgrade notice.
 - The established Win-Test handling for 24, 47 and 76 GHz remains unchanged. Their Worked flags are retained, while only frequencies represented by the project `Band` model can create worked-grid state.
 
+### Win-Test log recovery
+
+- Win-Test only broadcasts new QSOs. A listener started later never sees the earlier ones, so KST4Contest pulls them with the Win-Test `IHAVE` / `NEEDQSO` protocol, ported from the wtKST `WtLogSync` implementation. The answers are ordinary `ADDQSO` packets and reuse the established Worked path; the recovery itself never touches database or UI.
+- The recovery is not configurable. It is bound to the existing Win-Test network listener, runs automatically once a station is detected through `HELLO` or `STATUS`, and stays active so gaps caused by lost broadcasts are refetched.
+- The station-name filter remains a QRG-sync setting. Log recovery covers every station in the network, because each band station of a multi-station setup keeps its own log and contributes per-band Worked state.
+- A QSO is identified by `StationName@LogUniqueID` plus the Win-Test QSO number. That identity deduplicates the answers of overlapping requests, so a recovered log is written once instead of once per resend.
+- Win-Test framing must be resolved on the raw datagram bytes: the checksum byte is not valid ASCII and would otherwise corrupt the trailing fields, which carry the log ID of `ADDQSO` and the run-length inventory of `IHAVE`. A broken checksum discards `IHAVE` only; the established handling of the other message types is unchanged and still does not verify checksums.
+- Win-Test answers broadcasts only; an identical unicast request to the same station stays unanswered (verified against Win-Test). Outgoing Win-Test packets therefore derive their broadcast address from the source address of received Win-Test packets, with the configured address as fallback for a station behind a router. A configured address pointing at a non-existent network raises no send error, so it silently disabled both log recovery and SKED handover before. Only genuine Win-Test message types update that address; internal control packets such as the poison pill must not redirect outgoing traffic.
+- `IHAVE` inventories are run-length encoded and may be split, so the announced first row is honoured instead of assuming that an inventory starts at QSO number one. A station that never sends a usable inventory is served by a blind block fallback starting at QSO number one.
+
 ### Terrain data providers
 
 - The active terrain profile provider is Open-Meteo using Copernicus GLO-90 data.
@@ -162,6 +172,10 @@ The repository contains the KST4Contest website under `website/`, published sepa
 
 Current website/deployment scripts and update-feed behaviour must be inspected before changes; do not rely on historical assumptions.
 
+- `APPLICATION_CURRENT_VERSION` is the user-visible semantic version and must use the dotted `major.minor.patch` form. `APPLICATION_CURRENTVERSIONNUMBER` is retained only for older feeds and encodes patch releases by appending the patch digit, for example `1.43.1` as `1.431`.
+- The tagged-release workflow creates the GitHub Release before building the website update feed. This ordering is required because `versionInfo.js` reads the published release body through the GitHub Releases API.
+- After publication, the workflow tests and builds the website, validates the expected Stable version, attaches `kst4ContestVersionInfo.xml` to the release and uploads the complete website build as a workflow artifact.
+
 ## Important Decisions and Workarounds
 
 - Preserve full callsign/category identity while applying base-call normalisation only to specifically defined features.

github_docs/de-Changelog.md

@@ -8,6 +8,72 @@ Die veröffentlichten Stable-Versionen und ihre Programmpakete stehen unter [Git
 
 ---
 
+## v1.43.1 (2026-09-03)
+
+**Korrigierte Versionsmetadaten**
+
+v1.43.1 enthält dieselben funktionalen Änderungen wie v1.43.0. Korrigiert wurden die Anwendungs- und Build-Metadaten für Anzeige, ON4KST-Kennung und Update-Vergleich. Ein Teil der Metadaten des ersten v1.43.0-Pakets wies den Build noch als Version 1.42 aus.
+
+### Behoben
+
+- **Einheitliche semantische Version:** Die sichtbare Anwendungsversion verwendet jetzt vollständig `1.43.1`. Der kompakte Wert `1.431` bleibt ausschließlich im veralteten numerischen Feld für die Kompatibilität mit älteren Update-Feeds erhalten.
+
+- **Update-Feed im Tagged-Release-Workflow:** Website-Build, Prüfung des Versionsfeeds und Upload der Artefakte laufen jetzt tatsächlich nach der Veröffentlichung des GitHub Releases. Diese Schritte waren zuvor versehentlich in die Artefaktliste der Release-Action eingerückt und wurden deshalb übersprungen.
+
+Wer v1.43.0 installiert hat, sollte v1.43.1 verwenden. Die Funktionen bleiben unverändert; korrigiert werden nur die Versionsmetadaten und der Release-Workflow.
+
+Die korrigierte Version ist als [Release v1.43.1](https://github.com/praktimarc/kst4contest/releases/tag/v1.43.1) verfügbar.
+
+---
+
+## v1.43.0 (2026-09-03)
+
+**Zuverlässigere Log-Synchronisation, gespeicherte Tabellenlayouts und bessere DX-Cluster-Kompatibilität**
+
+v1.43 konzentriert sich auf die zuverlässige Verarbeitung externer Logdaten und den stabilen Betrieb während längerer Conteste. Hinzu kommen praktische Einstellmöglichkeiten für Tabellenlayouts und die Stationsgruppierung auf der Karte.
+
+### Neu
+
+- **Optionale Kartencluster:** **Group nearby stations** schaltet die räumliche Gruppierung bei niedrigen Zoomstufen unmittelbar ein oder aus. Die gespeicherte Auswahl verändert weder Kartenausschnitt noch Stationsauswahl; die Zusammenfassung aktiver Varianten desselben Basisrufzeichens bleibt davon unabhängig. Damit ist [Issue #79](https://github.com/praktimarc/kst4contest/issues/79) umgesetzt.
+
+- **Tabellenlayout automatisch gesichert:** Tabellen erhalten beim ersten brauchbaren Inhalt sinnvolle Breiten. Manuell geänderte Spaltenbreiten, Fenstergrößen und relevante Divider werden nach kurzer Verzögerung in `preferences.xml` geschrieben. Haupt- und Monitorfenster behalten getrennte Layouts für DXCluster und QSO of the other.
+
+- **Tooltips für gekürzte Tabellenwerte:** Normale Tabellenzellen zeigen ihren vollständigen Inhalt, wenn die sichtbare Spalte zu schmal ist. Funktionale Tooltips und anklickbare Links bleiben davon unberührt.
+
+- **Hinweis bei neu angelegtem Simplelogfile:** Fehlt die ausgewählte Datei, legt KST4Contest sie an und zeigt einen Hinweis mit Dateipfad, konkretem Testablauf und Link zum passenden Abschnitt des Handbuchs.
+
+### Geändert
+
+- **Robuste Simplelogfile-Auswertung:** Die ausgewählte Datei wird einmal pro Minute ausgewertet und nach jedem Durchlauf geschlossen, damit das Logprogramm sie ersetzen oder rotieren kann. Erkannte Rufzeichen setzen den globalen Worked-Status für alle aktiven Suffixvarianten des Basisrufzeichens. Bei deaktivierter Funktion findet kein Dateizugriff statt; Lese- oder Erstellungsfehler beenden die periodische Aufgabe nicht mehr.
+
+- **Einheitliche Bandwerte externer Logger:** UCXLog-kompatible Pakete und Win-Test-Ereignisse verwenden eine gemeinsame Bandnormalisierung. Numerische Werte, Meter- und Zentimeterangaben sowie die vorhandenen Win-Test-IDs setzen damit dieselben Worked-Markierungen und Worked-Großfelder. Insbesondere `2320`, `5760` und `10368` werden zuverlässig verarbeitet; bei fehlendem oder unbekanntem Band wird nur der globale Worked-Status gesetzt.
+
+- **Kompakte vollständige Frequenzen erkannt:** Vollständige Frequenzangaben ohne Dezimaltrenner werden auf allen unterstützten Bändern akzeptiert; die letzten drei Ziffern bilden den kHz-Anteil. Nackte dreistellige Zahlen benötigen weiterhin einen erkennbaren Frequenzkontext, damit Signalrapporte und andere Zahlen nicht als QRG behandelt werden.
+
+- **DXSpider-kompatibles Spotformat:** Lokale DX-Cluster-Spots verwenden eine feste 75-Zeichen-Nutzzeile mit dem DX-Rufzeichen ab Spalte 27, einem 30 Zeichen breiten Kommentarfeld und der UTC-Zeit ab Spalte 71. Das Format bleibt bis 24 GHz stabil. Überlange DX-Rufzeichen werden verworfen und protokolliert, statt unbemerkt abgeschnitten zu werden. Damit ist [Issue #86](https://github.com/praktimarc/kst4contest/issues/86) behoben.
+
+- **Aktive ON4KST-Verbindungsprüfung:** Ein ruhiger Chatserver wird mit einer expliziten, sitzungsweiten Abfrage geprüft, bevor die Verbindung als unterbrochen gilt. Heartbeat und Prüftelegramme behalten das erforderliche CR/LF-Framing.
+
+- **Zuverlässige Altersmarkierung privater Nachrichten:** Eingehende Privatnachrichten verwenden bis zu fünf Minuten lang die definierten grünen Altersstufen. Eigene Nachrichten behalten ihre separate Darstellung; leere oder wiederverwendete Tabellenzeilen kehren zum normalen Design zurück und behalten keine veraltete Hervorhebung.
+
+### Behoben
+
+- **Worked-Status nach dem Login:** Persistierte SQLite-Informationen werden vor der Veröffentlichung jeder initialen ON4KST-Benutzerliste geladen und angewendet. Erneute Verbindungen, beide Kategorien und alle aktiven Varianten eines Basisrufzeichens starten dadurch mit dem richtigen Status. Damit ist [Issue #85](https://github.com/praktimarc/kst4contest/issues/85) behoben.
+
+- **Fehlerhafte Trennung bei ruhigem Server:** Eine gültige ON4KST-Verbindung wird nicht mehr beendet, nur weil der Server gerade keine Aktivitätszeilen überträgt.
+
+### Dokumentation und Auslieferung
+
+- Das deutsche und englische Handbuch wurden mit der Implementierung abgeglichen und überarbeitet. Ein neues Kapitel zum Contest-Workflow verbindet die einzelnen Funktionen zu einem praktischen Betriebsablauf; außerdem wurden die Abschnitte zu Dual Chat, Privatnachrichten, QRG-Synchronisation, Simplelogfile-Auswertung und Konfiguration präzisiert.
+
+- Die Website beschreibt Band- und Richtungsgelegenheiten, Stationskarte, QRG-Verarbeitung, Filter, globale Nachrichtenansichten, Privatnachrichten und Log-Synchronisation jetzt ausführlicher.
+
+- Die AUR-Paketdefinitionen wurden auf v1.43.0 aktualisiert.
+
+Die vollständige Funktionalität von v1.43.0 steht im [Release v1.43.0](https://github.com/praktimarc/kst4contest/releases/tag/v1.43.0) bereit. Wegen der inkonsistenten eingebetteten Versionsmetadaten ist v1.43.1 der empfohlene Paketstand.
+
+---
+
 ## v1.42.0 (2026-08-22)
 
 **Gemeinsamer Bandkontext, sitzungsbasierte ON4KST-Verbindung und signierte macOS-Pakete**
@@ -38,21 +104,17 @@ v1.42 führt mehrere bisher getrennte Auswertungen zusammen. Bandinformationen,
 
 - **Filter zurücksetzen:** Ein eigener Reset-Button entfernt die aktiven Filterprädikate der Benutzerliste zuverlässig.
 
-- **Optionale Kartencluster:** **Group nearby stations** schaltet die räumliche Gruppierung bei niedrigen Zoomstufen unmittelbar ein oder aus. Die automatisch gespeicherte Auswahl verändert weder Kartenausschnitt noch Stationsauswahl; die Zusammenfassung aktiver Varianten desselben Basisrufzeichens bleibt davon unabhängig. Damit ist [Issue #79](https://github.com/praktimarc/kst4contest/issues/79) umgesetzt.
+- **Kartencluster:** Räumlich dicht beieinanderliegende Stationen werden bei niedrigen Zoomstufen zusammengefasst. Die ausgewählte Station und relevante Richtungsgelegenheiten bleiben einzeln sichtbar.
 
 - **Ausblendbare Streckenanalyse:** Geländeprofil und Analysebereich der Stationskarte können vollständig ausgeblendet werden. Die Auswahl wird gespeichert und beim nächsten Programmstart wiederhergestellt.
 
 ### Geändert
 
-- **Tabellenlayout automatisch gesichert:** Tabellen werden beim ersten brauchbaren Inhalt sinnvoll dimensioniert. Manuell geänderte Spaltenbreiten, Fenstergrößen und relevante Divider werden verzögert in `preferences.xml` gespeichert; Haupt- und Monitorfenster behalten für DXCluster und QSO of the other getrennte Layouts. Gekürzte normale Zellwerte zeigen ihren Volltext im Tooltip, ohne funktionale Tooltips oder anklickbare Links zu verdrängen.
-
-- **DX-Cluster-Zeilenformat vereinheitlicht:** Lokale Spots verwenden jetzt eine feste, DXSpider-kompatible 75-Zeichen-Nutzzeile mit dem DX-Rufzeichen ab Spalte 27, einem 30 Zeichen breiten Kommentarfeld und der UTC-Zeit ab Spalte 71. Das Format bleibt auch bei Mikrowellenfrequenzen bis 24 GHz stabil. Überlange DX-Rufzeichen werden verworfen und protokolliert, statt still abgeschnitten zu werden; AirScout- und Testkommentare sind entsprechend kompakter.
-
 - **Sessionbezogene ON4KST-Verbindungssteuerung:** Socket, Reader, Writer, Messagebus und Warteschlangen gehören jetzt zu einer eindeutig identifizierten Verbindungssession. Veraltete Threads einer abgelösten Verbindung können dadurch keine Daten mehr verarbeiten oder die neue Verbindung schließen. `ONLINE` wird erst nach bestätigtem Login und vollständig empfangenen Benutzerlisten gemeldet. Verbindungsaufbau, Login und Synchronisation besitzen feste Zeitlimits; Heartbeats, ausbleibende Eingangsdaten, EOF sowie Lese- und Schreibfehler werden überwacht und lösen bei Bedarf einen kontrollierten Neuaufbau mit Backoff aus.
 
 - **ON4KST-Protokollbefehle abgesichert:** Ausgehende Befehle werden zentral aufgebaut und auf gültige Kategorien, Locatoren und unerlaubte Frame-Trennzeichen geprüft. Da ON4KST pro TCP-Session nur einen Locator verwaltet, wird für beide Chat-Kategorien der Hauptlocator verwendet und eine abweichende zweite Konfiguration protokolliert, statt widersprüchliche Befehle an den Server zu senden.
 
-- **QRG-Erkennung präzisiert:** Vollständige Frequenzangaben werden auch ohne Dezimaltrenner erkannt; die letzten drei Ziffern bilden dabei den kHz-Anteil. Relative Frequenzen bleiben unverändert, und nackte dreistellige Zahlen gelten weiterhin nur bei erkennbarem Frequenzkontext als QRG. Signalrapporte, Bandangaben und andere Zahlen erzeugen dadurch seltener falsche Frequenzen.
+- **QRG-Erkennung präzisiert:** Vollständige und relative Frequenzangaben werden weiterhin erkannt. Nackte dreistellige Zahlen gelten nur noch bei erkennbarem Frequenzkontext als QRG. Signalrapporte, Bandangaben und andere Zahlen erzeugen dadurch seltener falsche Frequenzen.
 
 - **Stationsbezogener Frequenzkontext:** Bei relativen QRGs verwendet KST4Contest zuerst einen höchstens 30 Minuten alten Bandkontext derselben Station. Erst wenn dieser fehlt, wird das global konfigurierte Fallback-Band verwendet.
 
@@ -86,10 +148,6 @@ v1.42 führt mehrere bisher getrennte Auswertungen zusammen. Bandinformationen,
 
 - **DXLog-Gesamtlog übernommen:** Der UCXLog-kompatible UDP-Listener verarbeitet neben `contactinfo` auch `contactreplace`. Dadurch kann ein von DXLog.net als vollständiges Log ausgesendeter Datenbestand eingelesen werden.
 
-- **Logger-Bandwerte vereinheitlicht:** Numerische sowie Meter- und Zentimeterangaben aus UCXLog-kompatiblen QSO-Paketen und die Band-IDs von Win-Test werden einmal normalisiert und danach einheitlich für Worked-Markierungen und Worked-Großfelder verwendet. Dadurch setzen insbesondere `2320`, `5760` und `10368` zuverlässig ihre vorhandenen Bandmarkierungen. Bei einem fehlenden oder unbekannten Band bleibt es beim globalen Worked-Status.
-
-- **Simplelogfile-Verhalten präzisiert:** Die ausgewählte Textdatei wird einmal pro Minute mit einem festen Rufzeichenmuster ausgewertet. Treffer setzen den globalen Worked-Status aller aktiven Varianten des Basisrufzeichens, werden aber nicht in SQLite persistiert. Eine fehlende Datei wird angelegt; Lese- und Erstellungsfehler beenden die periodische Auswertung nicht. Ein Datenbank-Reset verändert die Datei nicht, sodass enthaltene Rufzeichen bei der nächsten Auswertung erneut als gearbeitet markiert werden.
-
 - **Automatische QRG-Übernahme abgesichert:** `MYQRG` wird nur von einer aktivierten Schnittstelle aktualisiert, die tatsächlich gültige `RadioInfo`- beziehungsweise Win-Test-`STATUS`-Pakete liefert. Eine aktivierte, aber nicht liefernde Quelle ersetzt die notwendige Funktionsprüfung oder manuelle QRG-Pflege nicht.
 
 - **Versionserkennung verbessert:** Versionsnummern werden semantisch verglichen, damit beispielsweise Patch-Versionen und Nightly-Stände nicht mehr durch eine einfache Fließkommazahl falsch eingeordnet werden.
@@ -98,8 +156,6 @@ v1.42 führt mehrere bisher getrennte Auswertungen zusammen. Bandinformationen,
 
 - **Zuverlässige Benutzerliste beim Login:** Ungültige oder unvollständige `UA0`-Teilnehmerdatensätze werden einzeln verworfen und protokolliert, ohne die Verarbeitung der alphabetisch folgenden Teilnehmer abzubrechen. Die gültigen Einträge werden zunächst pro Kategorie gesammelt und erst mit dem ersten zugehörigen `UE`-Abschlussframe vollständig veröffentlicht.
 
-- **Persistierter Worked-Status beim Listenaufbau:** Beim Abschluss jeder initialen ON4KST-Benutzerliste wird der SQLite-Zustand einmal geladen und vor der Veröffentlichung auf die neuen Chatmember angewendet. Das gilt für beide Kategorien, erneute Verbindungen und alle aktiven Varianten eines Basisrufzeichens.
-
 - **Benutzerliste verschwindet nach dem Login:** ON4KST kann nach Namens-, Status- oder anderen Live-Änderungen weitere `UE`-Frames für dieselbe Kategorie senden. Wiederholte Abschlussframes werden jetzt erkannt und ignoriert, damit eine bereits gefüllte Benutzerliste nicht durch eine leere Momentaufnahme ersetzt wird.
 
 - **Fehlgeschlagener Erstaufbau und Verbindungsverlust:** Wenn beim Programmstart keine Verbindung zum Server hergestellt werden kann, läuft KST4Contest nicht mehr in eine Endlos- oder Busy-Wait-Schleife. Die Oberfläche bleibt bedienbar und weitere Versuche erfolgen mit begrenztem Backoff. Auch ein vom Server geschlossener oder über längere Zeit stummer Socket wird zuverlässig erkannt.

github_docs/de-Log-Synchronisation.md

@@ -102,6 +102,24 @@ Die Band-IDs für 50 und 70 MHz werden ebenso verarbeitet wie die VHF-, UHF- und
 
 Die Daten werden in derselben internen Datenbank abgelegt wie Worked-Informationen aus den übrigen QSO-UDP-Schnittstellen und nach einem Neustart wiederhergestellt.
 
+#### Bereits geloggte QSOs nachladen
+
+Win-Test sendet jedes neue QSO als Broadcast. QSOs, die vor dem Start von KST4Contest geloggt wurden, sind darin nicht enthalten. KST4Contest fordert diese QSOs deshalb selbst an, sobald der Win-Test-Netzwerk-Listener eine Win-Test-Station im Netzwerk erkennt.
+
+Der Abgleich benötigt keine eigene Einstellung und keinen Bedienschritt:
+
+- Win-Test meldet mit `IHAVE`, welche QSO-Nummern welches Logs es führt.
+- KST4Contest fordert die fehlenden Bereiche mit `NEEDQSO` an, höchstens 50 QSOs pro Anfrage.
+- Win-Test beantwortet die Anfrage mit gewöhnlichen `ADDQSO`-Paketen. Sie werden genauso ausgewertet wie ein live geloggtes QSO.
+
+Bereits gearbeitete Stationen erscheinen dadurch auch dann als gearbeitet, wenn KST4Contest erst während des Contests gestartet wird. Der Abgleich bleibt anschließend aktiv und holt auch einzelne Pakete nach, die im laufenden Betrieb verloren gegangen sind. Bereits bekannte QSOs werden erkannt und nicht erneut gespeichert.
+
+Sind mehrere Win-Test-Stationen im Netzwerk aktiv, wird jedes Log abgeglichen. Damit sind die bandbezogenen Worked-Markierungen aller Bandstationen vollständig. Der Stationsnamensfilter wirkt weiterhin nur auf die QRG-Synchronisation und schränkt den Logabgleich nicht ein.
+
+Meldet eine erkannte Station kein auswertbares `IHAVE`, etwa bei einer älteren Win-Test-Version, fordert KST4Contest die QSOs blockweise ab QSO-Nummer 1 an, bis ein Block unbeantwortet bleibt.
+
+Voraussetzung ist ein aktiviertes Win-Test-Netzwerk. Ist das Win-Test-Netzwerk oder der Listener in KST4Contest deaktiviert, findet kein Abgleich statt.
+
 #### Skeds an Win-Test übergeben
 
 Mit **Create sked** wird zunächst ein interner KST4Contest-Sked angelegt. Ist der Win-Test-Netzwerk-Listener aktiviert, versucht KST4Contest anschließend automatisch, den Sked als `ADDSKED` an das Win-Test-Netzwerk zu übertragen.
@@ -154,7 +172,11 @@ Im Reiter **TRX sync**:
 - `Use pass frequency from Win-Test STATUS`
 - `Win-Test station name filter`
 
-Das Win-Test-Netzwerk muss in Win-Test aktiviert sein. Bei mehreren Computern muss die Broadcast-Adresse das betreffende lokale Netzwerk erreichen. Der Stationsname sollte die sendende KST4Contest-Instanz innerhalb des Win-Test-Netzwerks eindeutig erkennen lassen.
+Das Win-Test-Netzwerk muss in Win-Test aktiviert sein. Der Stationsname sollte die sendende KST4Contest-Instanz innerhalb des Win-Test-Netzwerks eindeutig erkennen lassen.
+
+Die Broadcast-Adresse ermittelt KST4Contest selbst: Aus der Absenderadresse der empfangenen Win-Test-Pakete wird das passende lokale Netzwerk bestimmt und dessen Broadcast-Adresse verwendet. Die eingetragene Adresse dient als Rückfallebene, wenn kein lokales Netzwerk zur Win-Test-Station passt, etwa wenn Win-Test hinter einem Router liegt.
+
+Das ist wichtig, weil Win-Test ausschließlich auf Broadcasts reagiert und eine Adresse in einem nicht vorhandenen Netzwerk keinen Fehler auslöst: Das Paket wird ohne Meldung weggeroutet. Eine veraltete Eintragung, etwa aus einem anderen Netzwerk, machte dadurch früher sowohl die Sked-Übergabe als auch den Logabgleich wirkungslos.
 
 Ausführliche Beschreibung der Einstellungen: [Win-Test-Netzwerk-Listener](de-Konfiguration#win-test-netzwerk-listener-ab-v131)
 

github_docs/en-Changelog.md

@@ -8,6 +8,72 @@ Published Stable versions and their application packages are available under [Gi
 
 ---
 
+## v1.43.1 (2026-09-03)
+
+**Corrected version metadata**
+
+v1.43.1 contains the same functional changes as v1.43.0. It corrects the application and build metadata used for display, ON4KST identification and update comparison. Some metadata in the first v1.43.0 package set still identified the build as version 1.42.
+
+### Fixed
+
+- **Consistent semantic version:** The user-visible application version now uses the complete `1.43.1` form. The compact value `1.431` remains only in the deprecated numeric field required for compatibility with older update feeds.
+
+- **Tagged-release update feed:** The website build, version-feed validation and artifact upload now run as actual workflow steps after the GitHub Release has been published. They were previously indented into the release action's artifact list and therefore skipped.
+
+Users of v1.43.0 should install v1.43.1. The functionality is unchanged; the update only corrects the version metadata and release workflow.
+
+The corrected version is available as [Release v1.43.1](https://github.com/praktimarc/kst4contest/releases/tag/v1.43.1).
+
+---
+
+## v1.43.0 (2026-09-03)
+
+**More reliable log synchronisation, persistent layouts and better DX Cluster compatibility**
+
+v1.43 concentrates on reliability around external log data and long-running contest operation. It also adds practical control over table layouts and station grouping on the map.
+
+### Added
+
+- **Optional map clustering:** **Group nearby stations** immediately enables or disables spatial grouping at lower zoom levels. The stored setting changes neither the viewport nor the selected station; aggregation of active variants sharing one base callsign remains independent. This implements [Issue #79](https://github.com/praktimarc/kst4contest/issues/79).
+
+- **Automatic table-layout persistence:** Tables receive useful widths when their first meaningful contents arrive. Manually changed column widths, window sizes and relevant dividers are written to `preferences.xml` after a short delay. The main and monitor windows keep separate DXCluster and QSO-of-the-other layouts.
+
+- **Tooltips for truncated table values:** Normal table cells expose their complete text when the visible column is too narrow, without replacing functional tooltips or clickable links.
+
+- **Simplelogfile creation notice:** When the selected file does not exist, KST4Contest creates it and displays a notice with the file path, a concrete test procedure and a link to the relevant manual section.
+
+### Changed
+
+- **Robust Simplelogfile evaluation:** The selected file is evaluated once per minute and closed after every pass so that the logging application can replace or rotate it. Detected callsigns apply the global Worked state to every active suffix variant of the base callsign. Disabling the function prevents any file access, while read or creation errors no longer terminate the periodic task.
+
+- **Consistent external logger bands:** UCXLog-compatible packets and Win-Test events use one shared band normalisation. Numeric values, metre and centimetre designators and the existing Win-Test IDs now set the same Worked flags and worked grid squares. Values including `2320`, `5760` and `10368` are handled reliably; a missing or unknown band sets only the global Worked state.
+
+- **Compact full-frequency recognition:** Complete frequencies without a decimal separator are accepted across the supported bands, with the final three digits interpreted as the kHz part. Bare three-digit numbers still require recognisable frequency context so that signal reports and unrelated numbers are not treated as QRGs.
+
+- **DXSpider-compatible spot format:** Local DX Cluster spots use a fixed 75-character payload line with the DX callsign in column 27, a 30-character comment field and UTC time in column 71. The format remains stable up to 24 GHz. Overlong DX callsigns are rejected and logged instead of being silently truncated. This resolves [Issue #86](https://github.com/praktimarc/kst4contest/issues/86).
+
+- **Active ON4KST connection probe:** A quiet chat server is checked with an explicit session-wide probe before the connection is treated as dead. Heartbeats and probe frames retain the required CR/LF framing.
+
+- **Reliable private-message age highlighting:** Incoming private messages use the defined green age levels for up to five minutes. Locally sent messages retain their separate style, and empty or reused table rows return to the normal design instead of keeping an obsolete highlight.
+
+### Fixed
+
+- **Worked state after login:** Persisted SQLite Worked information is loaded and applied before each initial ON4KST user list is published. Reconnects, both categories and all active variants of a base callsign therefore start with the correct state. This resolves [Issue #85](https://github.com/praktimarc/kst4contest/issues/85).
+
+- **False disconnect during quiet periods:** A valid ON4KST connection is no longer closed merely because the server currently has no activity lines to send.
+
+### Documentation and packaging
+
+- The German and English manuals were revised against the implementation. A new contest-workflow chapter connects the individual functions into a practical operating sequence, while the sections on dual chat, private-message handling, QRG synchronisation, Simplelogfile evaluation and configuration were clarified.
+
+- The website feature pages now describe band and direction opportunities, the station map, QRG handling, filters, global message views, private-message handling and logger synchronisation in more detail.
+
+- The AUR package definitions were updated for v1.43.0.
+
+The complete v1.43.0 functionality is available in [Release v1.43.0](https://github.com/praktimarc/kst4contest/releases/tag/v1.43.0). Because its embedded version metadata is inconsistent, v1.43.1 is the recommended package set.
+
+---
+
 ## v1.42.0 (2026-08-22)
 
 **Shared band context, session-based ON4KST connection and signed macOS packages**
@@ -38,21 +104,17 @@ v1.42 brings several previously separate calculations together. Band information
 
 - **Filter reset:** A dedicated reset button reliably removes the active user-list filter predicates.
 
-- **Optional map clustering:** **Group nearby stations** immediately enables or disables spatial grouping at lower zoom levels. The automatically stored setting changes neither the viewport nor the selected station; aggregation of active variants sharing one base callsign remains independent. This implements [Issue #79](https://github.com/praktimarc/kst4contest/issues/79).
+- **Map clustering:** Stations close to each other are grouped at lower zoom levels. The selected station and relevant direction opportunities remain individually visible.
 
 - **Hideable path analysis:** The terrain profile and analysis section of the station map can be hidden completely. The selected state is stored and restored at the next application start.
 
 ### Changed
 
-- **Automatic table-layout persistence:** Tables receive useful widths when their first meaningful contents arrive. Manually changed column widths, window sizes and relevant dividers are written to `preferences.xml` after a short delay; the main and monitor windows keep separate DXCluster and QSO-of-the-other layouts. Truncated normal cell values expose their full text in a tooltip without replacing functional tooltips or clickable links.
-
-- **Unified DX Cluster line format:** Local spots now use a fixed, DXSpider-compatible 75-character payload line with the DX callsign in column 27, a 30-character comment field and UTC time in column 71. The layout remains stable for microwave frequencies up to 24 GHz. Overlong DX callsigns are rejected and logged instead of being silently truncated; AirScout and test comments are correspondingly more compact.
-
 - **Session-based ON4KST connection lifecycle:** Each socket, reader, writer, message bus and queue now belongs to an explicitly identified connection session. Delayed threads from an obsolete connection can therefore no longer process data or close its replacement. `ONLINE` is reported only after the login has been accepted and all requested user lists have been received. Connection setup, login and synchronisation use bounded timeouts, while heartbeats, missing inbound traffic, EOF and read or write failures trigger controlled reconnect attempts with backoff where appropriate.
 
 - **Validated ON4KST protocol commands:** Outgoing frames are built centrally and checked for valid categories, locators and prohibited frame delimiters. Because ON4KST maintains one locator per TCP session, the main locator is used for both chat categories and a conflicting secondary configuration is logged instead of sending contradictory commands to the server.
 
-- **More precise QRG recognition:** Complete frequencies are also recognised without a decimal separator, with the final three digits interpreted as the kHz part. Relative frequencies remain unchanged, and bare three-digit numbers still require recognisable frequency context. Signal reports, band designators and unrelated numbers therefore produce fewer false frequencies.
+- **More precise QRG recognition:** Complete and relative frequency references continue to be recognised. Bare three-digit numbers are treated as QRGs only when a frequency context is available. Signal reports, band designators and unrelated numbers therefore produce fewer false frequencies.
 
 - **Station-specific frequency context:** For relative QRGs, KST4Contest first uses a band context for the same station which is no more than 30 minutes old. The globally configured fallback band is used only when this context is unavailable.
 
@@ -86,10 +148,6 @@ v1.42 brings several previously separate calculations together. Band information
 
 - **DXLog full-log import:** In addition to `contactinfo`, the UCXLog-compatible UDP listener processes `contactreplace`. This allows a complete log broadcast by DXLog.net to be imported.
 
-- **Consistent logger band values:** Numeric, metre and centimetre values from UCXLog-compatible QSO packets and Win-Test band IDs are normalised once and then used consistently for Worked marks and worked grid squares. In particular, `2320`, `5760` and `10368` now reliably set their existing band marks. A missing or unknown band continues to set only the global Worked status.
-
-- **Defined Simplelogfile behaviour:** The selected text file is evaluated once per minute using a fixed callsign pattern. Matches set the global Worked status for all active variants of the base callsign but are not persisted in SQLite. A missing file is created, and read or creation errors do not terminate the periodic task. A database reset does not change the file, so callsigns contained in it are marked as worked again during the next evaluation.
-
 - **Guarded automatic QRG updates:** `MYQRG` is updated only by an enabled interface which actually supplies valid `RadioInfo` or Win-Test `STATUS` packets. An enabled source which provides no data does not remove the need for a functional check or manual QRG maintenance.
 
 - **Improved version comparison:** Versions are compared semantically so that patch releases and Nightly versions are not misclassified by conversion to a floating-point number.
@@ -98,8 +156,6 @@ v1.42 brings several previously separate calculations together. Band information
 
 - **Reliable initial user list:** Invalid or incomplete `UA0` member records are rejected and logged individually without preventing alphabetically following members from being processed. Valid entries are staged per category and published as one complete snapshot when the first corresponding `UE` end marker is received.
 
-- **Persisted Worked state during initial-list setup:** At the end of each initial ON4KST user list, the SQLite state is loaded once and applied to the new chat members before publication. This covers both categories, reconnects and every active variant of a base callsign.
-
 - **User list disappearing after login:** ON4KST may send additional `UE` frames for the same category after name, state or other live updates. Repeated end markers are now detected and ignored so that an already populated user list cannot be replaced by an empty snapshot.
 
 - **Failed initial connection and lost sockets:** An unavailable server during startup no longer sends KST4Contest into an endless or busy-wait loop. The user interface remains responsive and further attempts use bounded reconnect backoff. Sockets closed by the server, or connections without inbound traffic for an excessive period, are also detected reliably.

github_docs/en-Log-Sync.md

@@ -102,6 +102,24 @@ Band IDs for 50 and 70 MHz are processed in the same way as the VHF, UHF and SHF
 
 The information is written to the same internal database as Worked data received through the other QSO UDP interfaces and is restored after a restart.
 
+#### Recovering QSOs logged earlier
+
+Win-Test broadcasts every new QSO. QSOs logged before KST4Contest was started are not part of those broadcasts. KST4Contest therefore requests them itself as soon as the Win-Test network listener detects a Win-Test station on the network.
+
+The recovery needs no dedicated setting and no operating step:
+
+- Win-Test announces with `IHAVE` which QSO numbers of which log it holds.
+- KST4Contest requests the missing ranges with `NEEDQSO`, at most 50 QSOs per request.
+- Win-Test answers with ordinary `ADDQSO` packets. They are processed exactly like a QSO logged live.
+
+Stations already worked therefore appear as worked even when KST4Contest is started during the contest. The recovery stays active afterwards and also picks up individual packets lost during operation. Known QSOs are recognised and not stored again.
+
+When several Win-Test stations are active on the network, every log is recovered. The per-band Worked marks of all band stations are then complete. The station name filter still applies to the QRG synchronisation only and does not restrict the log recovery.
+
+If a detected station sends no usable `IHAVE`, for example an older Win-Test version, KST4Contest requests the QSOs in blocks starting at QSO number 1 until a block remains unanswered.
+
+The Win-Test network must be enabled. No recovery takes place while the Win-Test network or the listener in KST4Contest is disabled.
+
 #### Handing skeds over to Win-Test
 
 Pressing **Create sked** first creates an internal KST4Contest sked. If the Win-Test network listener is enabled, KST4Contest then automatically attempts to send the sked to the Win-Test network as an `ADDSKED` packet.
@@ -154,7 +172,11 @@ In the **TRX sync** tab:
 - `Use pass frequency from Win-Test STATUS`
 - `Win-Test station name filter`
 
-The Win-Test network must be enabled in Win-Test. When several computers are used, the broadcast address must reach the relevant local network. The station name should identify the sending KST4Contest instance unambiguously within the Win-Test network.
+The Win-Test network must be enabled in Win-Test. The station name should identify the sending KST4Contest instance unambiguously within the Win-Test network.
+
+KST4Contest determines the broadcast address itself: the source address of the received Win-Test packets identifies the matching local network, and the broadcast address of that network is used. The configured address serves as the fallback when no local network matches the Win-Test station, for example when Win-Test is located behind a router.
+
+This matters because Win-Test only reacts to broadcasts, and an address in a network that does not exist raises no error: the packet is routed away silently. An outdated entry, for instance from a different network, therefore used to disable both the sked handover and the log recovery.
 
 Detailed settings: [Win-Test Network Listener](en-Configuration#win-test-network-listener-from-v131)
 

packaging/aur/kst4contest-bin/.SRCINFO

@@ -1,6 +1,6 @@
 pkgbase = kst4contest-bin
 	pkgdesc = ON4KST Chat Client for VHF/UHF contest operation (pre-built)
-	pkgver = 1.42.0
+	pkgver = 1.43.1
 	pkgrel = 1
 	url = https://github.com/praktimarc/kst4contest
 	arch = x86_64
@@ -10,7 +10,7 @@ pkgbase = kst4contest-bin
 	provides = kst4contest
 	conflicts = kst4contest
 	conflicts = kst4contest-git
-	source = KST4Contest-v1.42.0-archlinux-x86_64.pkg.tar.zst::https://github.com/praktimarc/kst4contest/releases/download/v1.42.0/KST4Contest-v1.42.0-archlinux-x86_64.pkg.tar.zst
+	source = KST4Contest-v1.43.1-archlinux-x86_64.pkg.tar.zst::https://github.com/praktimarc/kst4contest/releases/download/v1.43.1/KST4Contest-v1.43.1-archlinux-x86_64.pkg.tar.zst
-	sha256sums = 3d8ac19c9f9d3ab0bdaf0ea621de0aa18c64f442c8776d28bfad607522aaf02b
+	sha256sums = 99cff343005b2e14c240928552a3cc98e1115014a80b1b8b41cbc86a082eb10c
 
 pkgname = kst4contest-bin

packaging/aur/kst4contest-bin/PKGBUILD

@@ -1,6 +1,6 @@
 # Maintainer: Philipp Wagner <philipp@wagnersnetz.de>
 pkgname=kst4contest-bin
-pkgver=1.42.0
+pkgver=1.43.1
 pkgrel=1
 pkgdesc="ON4KST Chat Client for VHF/UHF contest operation (pre-built)"
 arch=('x86_64')
@@ -10,7 +10,7 @@ depends=('gst-plugins-base' 'gst-plugins-good')
 provides=('kst4contest')
 conflicts=('kst4contest' 'kst4contest-git')
 source=("KST4Contest-v${pkgver}-archlinux-${CARCH}.pkg.tar.zst::https://github.com/praktimarc/kst4contest/releases/download/v${pkgver}/KST4Contest-v${pkgver}-archlinux-${CARCH}.pkg.tar.zst")
-sha256sums=('3d8ac19c9f9d3ab0bdaf0ea621de0aa18c64f442c8776d28bfad607522aaf02b')
+sha256sums=('99cff343005b2e14c240928552a3cc98e1115014a80b1b8b41cbc86a082eb10c')
 
 package() {
     cp -a "${srcdir}/usr" "${pkgdir}/"

packaging/aur/kst4contest-git/.SRCINFO

@@ -1,6 +1,6 @@
 pkgbase = kst4contest-git
 	pkgdesc = ON4KST Chat Client for VHF/UHF contest operation (git)
-	pkgver = 1.42.0.r256.g8aadbb9
+	pkgver = 1.43.1.r294.g7ee50267
 	pkgrel = 1
 	url = https://github.com/praktimarc/kst4contest
 	arch = x86_64

packaging/aur/kst4contest-git/PKGBUILD

@@ -1,6 +1,6 @@
 # Maintainer: Philipp Wagner <philipp@wagnersnetz.de>
 pkgname=kst4contest-git
-pkgver=1.42.0.r256.g8aadbb9
+pkgver=1.43.1.r294.g7ee50267
 pkgrel=1
 pkgdesc="ON4KST Chat Client for VHF/UHF contest operation (git)"
 arch=('x86_64')

packaging/aur/kst4contest/.SRCINFO

@@ -1,6 +1,6 @@
 pkgbase = kst4contest
 	pkgdesc = ON4KST Chat Client for VHF/UHF contest operation
-	pkgver = 1.42.0
+	pkgver = 1.43.1
 	pkgrel = 1
 	url = https://github.com/praktimarc/kst4contest
 	arch = x86_64
@@ -12,7 +12,7 @@ pkgbase = kst4contest
 	provides = kst4contest
 	conflicts = kst4contest-bin
 	conflicts = kst4contest-git
-	source = kst4contest-1.42.0.tar.gz::https://github.com/praktimarc/kst4contest/archive/refs/tags/v1.42.0.tar.gz
+	source = kst4contest-1.43.1.tar.gz::https://github.com/praktimarc/kst4contest/archive/refs/tags/v1.43.1.tar.gz
-	sha256sums = bd396387b8de41aac706458d5ebf64140ab3e83b8a7c710b66aa802bd48e804e
+	sha256sums = 15045996af3ec2dd5008e35d90fe2882bcbe4043b42614365bf2c2aa7696f817
 
 pkgname = kst4contest

packaging/aur/kst4contest/PKGBUILD

@@ -1,6 +1,6 @@
 # Maintainer: Philipp Wagner <philipp@wagnersnetz.de>
 pkgname=kst4contest
-pkgver=1.42.0
+pkgver=1.43.1
 pkgrel=1
 pkgdesc="ON4KST Chat Client for VHF/UHF contest operation"
 arch=('x86_64')
@@ -11,7 +11,7 @@ makedepends=('java-environment=21' 'maven')
 provides=('kst4contest')
 conflicts=('kst4contest-bin' 'kst4contest-git')
 source=("${pkgname}-${pkgver}.tar.gz::https://github.com/praktimarc/kst4contest/archive/refs/tags/v${pkgver}.tar.gz")
-sha256sums=('bd396387b8de41aac706458d5ebf64140ab3e83b8a7c710b66aa802bd48e804e')
+sha256sums=('15045996af3ec2dd5008e35d90fe2882bcbe4043b42614365bf2c2aa7696f817')
 
 build() {
     cd "${srcdir}/kst4contest-${pkgver}"

pom.xml

@@ -6,7 +6,7 @@
 
     <groupId>de.x08</groupId>
     <artifactId>praktiKST</artifactId>
-    <version>1.42.0-nightly</version>
+    <version>1.44.0-nightly</version>
 
     <name>praktiKST</name>
 

src/main/java/kst4contest/ApplicationConstants.java

@@ -20,14 +20,14 @@ public class ApplicationConstants {
     /**
      * Version shown to the user and used for semantic version comparison.
      */
-    public static final String APPLICATION_CURRENT_VERSION = "1.43";
+    public static final String APPLICATION_CURRENT_VERSION = "1.44.0";
 
     /**
      * Legacy numeric representation used only while older update feeds and
      * application versions still exist.
      */
     @Deprecated
-    public static final double APPLICATION_CURRENTVERSIONNUMBER = 1.42;
+    public static final double APPLICATION_CURRENTVERSIONNUMBER = 1.44;
 
     public static final String VERSIONINFOURLFORUPDATES_KST4CONTEST = "https://kst4contest.hamradioonline.de/kst4ContestVersionInfo.xml";
     public static final String VERSIONINFDOWNLOADEDLOCALFILE  = "kst4ContestVersionInfo.xml";

src/main/java/kst4contest/controller/ChatController.java

@@ -1204,7 +1204,8 @@ public class ChatController implements ThreadStatusCallback, PstRotatorEventList
 					return;
 				}
 
-				InetAddress broadcastAddress = InetAddress.getByName(
+				InetAddress broadcastAddress =
+						winTestAddressResolver.resolveBroadcastAddress(
 								chatPreferences
 										.getLogsynch_wintestNetworkBroadcastAddress()
 						);
@@ -1642,11 +1643,26 @@ public class ChatController implements ThreadStatusCallback, PstRotatorEventList
 //	private String hostname = "109.90.0.130";
     private String hostname;
 //	private String praktiKSTVersion = "praktiKST 1.0";
-	private String praktiKSTVersionInfo = "2022-10 - 2022-12\ndeveloped by DO5AMF, Marc\nContact: praktimarc@gmail.com\nDonations via paypal are welcome";
+	private String praktiKSTVersionInfo = "2022-10 - 2022-12\ndeveloped by DO5AMF, Marc and DN9APW, Philipp Wagner\nContact: praktimarc@gmail.com\nDonations via paypal are welcome";
 
 	private int port = 23001; // kst4contest.test 4 23001 //TODO: auslagern in Chatprefs
 	private ReadUDPbyUCXMessageThread readUDPbyUCXThread;
     private ReadUDPByWintestThread readUDPByWintestThread;
+
+	/**
+	 * Shared resolver for the Win-Test broadcast address. Win-Test only reacts
+	 * to broadcasts, so both the log synchronization and the SKED handover have
+	 * to reach the network the station was actually heard on.
+	 */
+	private final WinTestNetworkAddressResolver winTestAddressResolver =
+			new WinTestNetworkAddressResolver();
+
+	/**
+	 * @return resolver for outgoing Win-Test packets
+	 */
+	public WinTestNetworkAddressResolver getWinTestAddressResolver() {
+		return winTestAddressResolver;
+	}
 	private WriteThread writeThread;
 	private ReadThread readThread;
 	private InputReaderThread consoleReader;

src/main/java/kst4contest/controller/ReadUDPByWintestThread.java

@@ -13,8 +13,9 @@ import java.net.*;
 import java.nio.charset.StandardCharsets;
 import java.util.ArrayList;
 import java.util.Arrays;
+import java.util.HashMap;
+import java.util.List;
 import java.util.Map;
-import java.util.concurrent.ConcurrentHashMap;
 import java.util.regex.Matcher;
 import java.util.regex.Pattern;
 
@@ -31,18 +32,40 @@ public class ReadUDPByWintestThread extends Thread {
 
     private static final int BUFFER_SIZE = 4096;
 
-    private final Map<Integer, String> receivedQsos = new ConcurrentHashMap<>();
     private long lastPacketTime = 0;
 
     private String myStation = "DO5AMF";
 
     private String targetStation = "";
     private String stationID = "";
-    private int lastKnownQso = 0;
 
     private ThreadStatusCallback callBackToController;
     private String ThreadNickName = "Wintest-msg";
 
+    /**
+     * Number of fields of a complete ADDQSO packet, including message type,
+     * source and destination.
+     */
+    private static final int ADDQSO_FIELD_COUNT = 24;
+
+    /** Field position of the Win-Test QSO number inside an ADDQSO packet. */
+    private static final int ADDQSO_QSO_NUMBER_INDEX = 11;
+
+    /** Field position of the logging station name inside an ADDQSO packet. */
+    private static final int ADDQSO_STATION_NAME_INDEX = 3;
+
+    private final WinTestLogSyncService logSyncService;
+
+    private WinTestLogSyncService.SyncState lastReportedSyncState;
+
+    /**
+     * Last IHAVE payload seen per station. Win-Test repeats the inventory
+     * periodically, so tracing only the changes keeps the output readable.
+     */
+    private final Map<String, String> lastTracedIhaveByStation = new HashMap<>();
+
+    private final WinTestNetworkAddressResolver addressResolver;
+
 
     public ReadUDPByWintestThread(ChatController client, ThreadStatusCallback callback) {
 
@@ -51,6 +74,21 @@ public class ReadUDPByWintestThread extends Thread {
         this.myStation = client.getChatPreferences().getStn_loginCallSignRaw(); //callsign of the logging stn
         this.PORT =  client.getChatPreferences().getLogsynch_wintestNetworkPort();
 
+        WinTestNetworkAddressResolver sharedAddressResolver =
+                client.getWinTestAddressResolver();
+        this.addressResolver = sharedAddressResolver != null
+                ? sharedAddressResolver
+                : new WinTestNetworkAddressResolver();
+
+        /*
+         * Preferences are read late on purpose: station name, port and broadcast
+         * address can be changed while the listener is running.
+         */
+        this.logSyncService = new WinTestLogSyncService(
+                this::sendNeedQso,
+                this::resolveOwnWinTestStationName
+        );
+
     }
 
     @Override
@@ -85,35 +123,113 @@ public class ReadUDPByWintestThread extends Thread {
 
         while (running) {
             try {
+                /*
+                 * DatagramPacket keeps the length of the previous datagram, so
+                 * without resetting it a long packet would be truncated after a
+                 * short one. A truncated packet loses its trailing fields and
+                 * its checksum.
+                 */
+                packet.setLength(buffer.length);
                 socket.receive(packet);
-                String msg = new String(packet.getData(), 0, packet.getLength(), StandardCharsets.US_ASCII).trim();
+                processWinTestDatagram(
-                processWinTestMessage(msg);
+                        packet.getData(), packet.getLength(), packet.getAddress());
             } catch (SocketTimeoutException e) {
-//                checkForMissingQsos();
+                logSyncService.tick();
+                reportSyncStateIfChanged();
             } catch (IOException e) {
                 //TODO: here is something to catch
             }
         }
     }
 
+    /**
+     * Resolves the Win-Test framing of a received datagram and processes it.
+     *
+     * <p>The checksum byte and the NUL terminator are removed on the raw bytes
+     * before any text parsing, so the trailing fields of the packet stay
+     * readable. Afterwards the log synchronization gets its chance to request
+     * QSOs that were logged before this listener was started.</p>
+     *
+     * @param datagram raw datagram buffer
+     * @param length number of valid bytes in the buffer
+     */
+    void processWinTestDatagram(byte[] datagram, int length, InetAddress source) {
+        if (datagram == null || length <= 0) {
+            return;
+        }
+
+        WinTestPacket packet = WinTestPacket.fromDatagram(datagram, length);
+
+        if (packet != null && isWinTestStationMessage(packet.getMessageType())) {
+            /*
+             * Win-Test only answers broadcasts. Remembering where its packets
+             * come from keeps outgoing requests on the network the station
+             * actually lives in, even when the configured broadcast address
+             * belongs to a different or no longer existing network.
+             */
+            addressResolver.rememberStationAddress(source);
+        }
+
+        if (packet == null) {
+            /*
+             * The datagram does not follow the Win-Test framing. It still
+             * reaches the established text handling, which also recognizes the
+             * poison pill that stops this listener.
+             */
+            processWinTestPacket(
+                    null,
+                    new String(datagram, 0, length, StandardCharsets.US_ASCII).trim()
+            );
+            return;
+        }
+
+        processWinTestPacket(packet, packet.getMessageText());
+
+        logSyncService.tick();
+        reportSyncStateIfChanged();
+    }
+
     void processWinTestMessage(String msg) {
+        processWinTestPacket(WinTestPacket.fromMessageText(msg), msg);
+    }
+
+    /**
+     * Processes one Win-Test message.
+     *
+     * @param packet parsed packet, or {@code null} when the message does not
+     *               follow the Win-Test framing
+     * @param msg complete message text
+     */
+    private void processWinTestPacket(WinTestPacket packet, String msg) {
 //        System.out.println("Wintest-Message received: " + msg);
 
+        if (msg == null) {
+            return;
+        }
+
         lastPacketTime = System.currentTimeMillis();
 
         if (msg.startsWith("HELLO:")) { //Client Signon of wintest
             parseHello(msg);
-            try {
-//                send_needqso();
-            }catch (Exception e) {
-                System.out.println("Error: ");
-                e.printStackTrace();
-            }
 
+            if (packet != null) {
+                System.out.println("[WinTest RX] HELLO from " + packet.getSource());
+                logSyncService.onStationSeen(packet.getSource());
+            }
 
         } else if (msg.startsWith("ADDQSO:")) { //adding qso to wintest log
             try {
 
+                if (packet != null && !packet.getDestination().isEmpty()) {
+                    /*
+                     * A directed ADDQSO is the answer to one of our NEEDQSO
+                     * requests. Tracing it separates a missing answer from a
+                     * failing evaluation of the answer.
+                     */
+                    System.out.println("[WinTest RX] ADDQSO answer from "
+                            + packet.getSource() + " to " + packet.getDestination());
+                }
+
                 parseAddQso(msg);
             } catch (Exception e) {
                 ThreadStateMessage threadStateMessage = new ThreadStateMessage(this.ThreadNickName, true, "Parsing ERROR: " + Arrays.toString(e.getStackTrace()), true);
@@ -123,8 +239,19 @@ public class ReadUDPByWintestThread extends Thread {
         } else if (msg.startsWith("STATUS")) {
             parseStatus(msg);
 
+            /*
+             * HELLO is only sent when a log is opened, so a listener that was
+             * started later learns about a station from its periodic STATUS.
+             * The configured station-name filter stays a QRG-sync setting: in a
+             * multi-station setup every band station keeps its own log, and all
+             * of them contribute Worked state.
+             */
+            if (packet != null) {
+                logSyncService.onStationSeen(packet.getSource());
+            }
+
         } else if (msg.startsWith("IHAVE:")) { //periodical message of wintest, which qsos are in the log
-//            parseIHave(msg); //TODO
+            parseIHave(packet);
         }
 
         else if (msg.contains(ApplicationConstants.DISCONNECT_RDR_POISONPILL)) {
@@ -138,6 +265,130 @@ public class ReadUDPByWintestThread extends Thread {
         callBackToController.onThreadStatus(ThreadNickName,threadStateMessage);
     }
 
+    /**
+     * Hands the periodic Win-Test log inventory to the log synchronization.
+     *
+     * <p>A packet with a broken checksum is discarded here. The run-length
+     * inventory is the last field of an IHAVE packet, so a corrupted packet
+     * would announce QSO ranges that do not exist. The established handling of
+     * the other message types is deliberately left unchanged, because it never
+     * verified the checksum.</p>
+     *
+     * @param packet received IHAVE packet
+     */
+    private void parseIHave(WinTestPacket packet) {
+        if (packet == null) {
+            return;
+        }
+
+        if (packet.isChecksumPresent() && !packet.isChecksumValid()) {
+            System.out.println("[WinTest] IHAVE with invalid checksum ignored");
+            return;
+        }
+
+        String tracedPayload = String.join(" ", packet.getDataTokens());
+        if (!tracedPayload.equals(lastTracedIhaveByStation.put(packet.getSource(), tracedPayload))) {
+            System.out.println("[WinTest RX] IHAVE from " + packet.getSource()
+                    + " to '" + packet.getDestination() + "': " + tracedPayload
+                    + (WinTestIhaveInventory.fromPacket(packet).isEmpty()
+                            ? "  <-- not usable as inventory" : ""));
+        }
+
+        logSyncService.onIhaveReceived(packet);
+    }
+
+    /**
+     * Reports a change of the log-synchronization progress to the controller.
+     */
+    private void reportSyncStateIfChanged() {
+        WinTestLogSyncService.SyncState currentSyncState = logSyncService.getState();
+
+        if (currentSyncState == lastReportedSyncState) {
+            return;
+        }
+
+        lastReportedSyncState = currentSyncState;
+
+        ThreadStateMessage threadStateMessage = new ThreadStateMessage(
+                this.ThreadNickName, true, "log sync: " + currentSyncState, false);
+        callBackToController.onThreadStatus(ThreadNickName, threadStateMessage);
+    }
+
+    /**
+     * Sends a NEEDQSO request as a UDP broadcast.
+     *
+     * <p>The framing follows the wtKST implementation exactly, including the
+     * leading blank of the data part:</p>
+     *
+     * <pre>
+     *   NEEDQSO: "KST4Contest" "STN1"  "STN1@44510" 1 50{checksum}\0
+     * </pre>
+     *
+     * @param targetStation Win-Test station the request is addressed to
+     * @param logId log identity in the form {@code StationName@LogUniqueID}
+     * @param countFrom first requested QSO number
+     * @param countTo last requested QSO number
+     */
+    private void sendNeedQso(String targetStation, String logId, long countFrom, long countTo) {
+        String data = " \"" + logId + "\" " + countFrom + " " + countTo;
+
+        WinTestMessage needQsoMessage = new WinTestMessage(
+                WinTestMessage.MessageType.NEEDQSO,
+                resolveOwnWinTestStationName(),
+                targetStation,
+                data
+        );
+
+        try (DatagramSocket sendSocket = new DatagramSocket()) {
+            sendSocket.setBroadcast(true);
+            sendSocket.setReuseAddress(true);
+
+            byte[] messageBytes = needQsoMessage.toBytes();
+            InetAddress broadcastAddress = addressResolver.resolveBroadcastAddress(
+                    client.getChatPreferences().getLogsynch_wintestNetworkBroadcastAddress());
+            int targetPort = client.getChatPreferences().getLogsynch_wintestNetworkPort();
+
+            sendSocket.send(new DatagramPacket(
+                    messageBytes, messageBytes.length, broadcastAddress, targetPort));
+
+            System.out.println("[WinTest LogSync] NEEDQSO to " + targetStation
+                    + " for " + logId + " " + countFrom + "-" + countTo);
+        } catch (IOException | RuntimeException exception) {
+            System.out.println("[WinTest LogSync] NEEDQSO could not be sent: "
+                    + exception.getMessage());
+        }
+    }
+
+    /**
+     * @return own station name in the Win-Test network, never blank
+     */
+    private String resolveOwnWinTestStationName() {
+        String configuredStationName =
+                client.getChatPreferences().getLogsynch_wintestNetworkStationNameOfKST();
+
+        if (configuredStationName == null || configuredStationName.isBlank()) {
+            return "KST4Contest";
+        }
+
+        return configuredStationName.trim();
+    }
+
+    /**
+     * Checks whether a message type identifies a genuine Win-Test station.
+     *
+     * <p>Internal control messages such as the poison pill must not influence
+     * the address of outgoing Win-Test packets.</p>
+     *
+     * @param messageType message type of a received packet
+     * @return {@code true} for a Win-Test station message
+     */
+    private static boolean isWinTestStationMessage(String messageType) {
+        return "HELLO".equals(messageType)
+                || "STATUS".equals(messageType)
+                || "IHAVE".equals(messageType)
+                || "ADDQSO".equals(messageType);
+    }
+
     /**
      * parsing of the hello message of wintest:
      * "HELLO: "STN1" "" 6667 130 "SLAVE" 1 0 1762201985"
@@ -346,15 +597,6 @@ public class ReadUDPByWintestThread extends Thread {
         }
     }
 
-//    private void send_needqso() throws IOException {
-//        String payload = String.format("NEEDQSO:\"%s\" \"%s\" \"%s\" %d %d?\0",
-//                "DO5AMF", "STN1", stationID, 1, 9999);
-//        InetAddress broadcast = InetAddress.getByName("255.255.255.255");
-//        byte[] bytes = payload.getBytes(StandardCharsets.US_ASCII);
-//        bytes[bytes.length - 2] = util_calculateChecksum((bytes));
-//        socket.send(new DatagramPacket(bytes, bytes.length, broadcast, 9871));
-//    }
-
 //    private void send_hello() throws IOException {
 //        String payload = String.format("HELLO:\"%s\" \"%s\" \"%s\" %d %d?\0",
 //                "DO5AMF", "", stationID, "SLAVE", 1, 14);
@@ -390,6 +632,61 @@ public class ReadUDPByWintestThread extends Thread {
         return packetFields.length > 3 ? packetFields[3] : "";
     }
 
+    /**
+     * Builds the log identity of an ADDQSO packet.
+     *
+     * <p>Win-Test numbers the QSOs of every log continuously, so a QSO is only
+     * identified by the combination of the logging station, the unique log ID
+     * and the QSO number. The log ID is the last field of the packet.</p>
+     *
+     * @param packetFields fields of the ADDQSO packet
+     * @return identity in the form {@code StationName@LogUniqueID}, or
+     *         {@code null} when the packet does not carry both values
+     */
+    static String extractLogIdFromWinTestAddQso(List<String> packetFields) {
+        if (packetFields == null || packetFields.size() < ADDQSO_FIELD_COUNT) {
+            return null;
+        }
+
+        String stationName = packetFields.get(ADDQSO_STATION_NAME_INDEX);
+        String logUniqueId = packetFields.get(packetFields.size() - 1);
+
+        if (stationName == null || stationName.isBlank()
+                || logUniqueId == null || logUniqueId.isBlank()) {
+            return null;
+        }
+
+        return stationName.trim() + "@" + logUniqueId.trim();
+    }
+
+    /**
+     * Extracts the Win-Test QSO number of an ADDQSO packet.
+     *
+     * <p>Win-Test sends {@code 0} instead of {@code 1} for the first QSO of a
+     * log in some situations. wtKST corrects that the same way.</p>
+     *
+     * @param packetFields fields of the ADDQSO packet
+     * @return QSO number, or {@code 0} when the packet carries no usable value
+     */
+    static long extractQsoNumberFromWinTestAddQso(List<String> packetFields) {
+        if (packetFields == null || packetFields.size() < ADDQSO_FIELD_COUNT) {
+            return 0L;
+        }
+
+        String rawQsoNumber = packetFields.get(ADDQSO_QSO_NUMBER_INDEX);
+
+        if (rawQsoNumber == null) {
+            return 0L;
+        }
+
+        try {
+            long qsoNumber = Long.parseLong(rawQsoNumber.trim());
+            return qsoNumber <= 0L ? 1L : qsoNumber;
+        } catch (NumberFormatException exception) {
+            return 0L;
+        }
+    }
+
     /**
      * Extracts the locator from a Win-Test ADDQSO packet.
      *
@@ -443,6 +740,17 @@ public class ReadUDPByWintestThread extends Thread {
      */
     private void parseAddQso(String msg) {
         try {
+            List<String> packetFields = WinTestPacket.tokenize(msg);
+            String logId = extractLogIdFromWinTestAddQso(packetFields);
+            long qsoNumber = extractQsoNumberFromWinTestAddQso(packetFields);
+
+            /*
+             * The QSO number is registered before any validation. Otherwise the
+             * log synchronization would request a QSO with unusable content
+             * over and over again.
+             */
+            boolean isUnknownQso = logSyncService.registerReceivedQso(logId, qsoNumber);
+
             String[] quotedParts = msg == null ? new String[0] : msg.split("\"");
             String callSign = quotedParts.length > 7 ? quotedParts[7] : "";
             String rawBandId = extractBandIdFromWinTestAddQso(msg);
@@ -455,6 +763,16 @@ public class ReadUDPByWintestThread extends Thread {
                 return;
             }
 
+            if (!isUnknownQso) {
+                /*
+                 * Win-Test resends known QSOs when a NEEDQSO request overlaps
+                 * with QSOs that already arrived as a broadcast. Worked state
+                 * and database entry exist in that case, so repeating the write
+                 * would only cost time during the initial log recovery.
+                 */
+                return;
+            }
+
             if (loggedBand == null && !rawBandId.isEmpty()) {
                 System.out.println("[WinTestUDPRcvr: warning] Unknown band ID: " + rawBandId);
             }

src/main/java/kst4contest/controller/WinTestIhaveInventory.java

@@ -0,0 +1,217 @@
+package kst4contest.controller;
+
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.List;
+import java.util.Optional;
+
+/**
+ * Inventory of one Win-Test log, transported in an {@code IHAVE} packet.
+ *
+ * <p>Win-Test announces which QSO numbers of a log a station currently holds.
+ * To keep the packet short the inventory is run-length encoded:</p>
+ *
+ * <pre>
+ *   IHAVE: "Shack" "" "Shack@9" E 1 1 911-1-117
+ *                     ^logId    ^  ^ ^ ^run lengths
+ *                            origin | initial state
+ *                                   first row
+ * </pre>
+ *
+ * <p>The run lengths alternate between present and missing QSOs, starting with
+ * the state given by {@code InitialState} at QSO number {@code FirstRow}. The
+ * example above therefore means: QSOs 1 to 911 are present, QSO 912 is missing
+ * and QSOs 913 to 1029 are present again.</p>
+ *
+ * <p>Unlike the wtKST implementation this parser honours {@code FirstRow}
+ * instead of assuming that every inventory starts at QSO number one. Win-Test
+ * splits long inventories into several packets, and a split inventory starts at
+ * a higher first row.</p>
+ */
+public final class WinTestIhaveInventory {
+
+	/** Where the sending station got the log from. */
+	public enum Origin {
+		/** The station owns the log or the operator is logged on there. */
+		OWNER,
+		/** The station only mirrors a log owned by somebody else. */
+		LOGGED_ELSE
+	}
+
+	/** Protects against endless loops caused by a corrupted run-length chain. */
+	private static final int MAX_SEGMENTS = 512;
+
+	private static final int EXPECTED_FIELD_COUNT = 5;
+
+	private final String logId;
+	private final Origin origin;
+	private final List<WinTestLogSegment> segments;
+
+	private WinTestIhaveInventory(String logId, Origin origin, List<WinTestLogSegment> segments) {
+		this.logId = logId;
+		this.origin = origin;
+		this.segments = segments;
+	}
+
+	/**
+	 * Parses an {@code IHAVE} packet.
+	 *
+	 * @param packet received packet
+	 * @return inventory, or an empty value when the packet is not a usable
+	 *         {@code IHAVE} announcement
+	 */
+	public static Optional<WinTestIhaveInventory> fromPacket(WinTestPacket packet) {
+		if (packet == null || !"IHAVE".equals(packet.getMessageType())) {
+			return Optional.empty();
+		}
+
+		List<String> fields = packet.getDataTokens();
+		if (fields.size() != EXPECTED_FIELD_COUNT) {
+			/*
+			 * Win-Test versions before 1.29 use a shorter IHAVE format without
+			 * run-length encoding. It carries no usable range information, so
+			 * the blind fallback of the sync service has to take over.
+			 */
+			return Optional.empty();
+		}
+
+		String parsedLogId = fields.get(0) == null ? "" : fields.get(0).trim();
+		if (parsedLogId.isEmpty()) {
+			return Optional.empty();
+		}
+
+		Origin parsedOrigin = parseOrigin(fields.get(1));
+
+		long firstRow = parseUnsignedValue(fields.get(2));
+		long initialState = parseUnsignedValue(fields.get(3));
+
+		if (firstRow < 1L || initialState < 0L || initialState > 1L) {
+			return Optional.empty();
+		}
+
+		List<WinTestLogSegment> parsedSegments =
+				parseRunLengths(fields.get(4), firstRow, initialState == 1L);
+
+		if (parsedSegments == null) {
+			return Optional.empty();
+		}
+
+		return Optional.of(new WinTestIhaveInventory(parsedLogId, parsedOrigin, parsedSegments));
+	}
+
+	private static Origin parseOrigin(String rawOrigin) {
+		if (rawOrigin == null) {
+			return Origin.OWNER;
+		}
+
+		String normalizedOrigin = rawOrigin.trim().toUpperCase(java.util.Locale.ROOT);
+		if ("E".equals(normalizedOrigin) || "LOGGEDELSE".equals(normalizedOrigin)) {
+			return Origin.LOGGED_ELSE;
+		}
+		return Origin.OWNER;
+	}
+
+	/**
+	 * Expands the hyphen-separated run lengths into ranges.
+	 *
+	 * @param rawRunLengths run-length chain such as {@code 911-1-117}
+	 * @param firstRow QSO number the first run starts at
+	 * @param startsPresent {@code true} when the first run describes present QSOs
+	 * @return ranges of present QSOs, or {@code null} for an unusable chain
+	 */
+	private static List<WinTestLogSegment> parseRunLengths(
+			String rawRunLengths,
+			long firstRow,
+			boolean startsPresent
+	) {
+		if (rawRunLengths == null || rawRunLengths.isBlank()) {
+			return null;
+		}
+
+		String[] runLengths = rawRunLengths.trim().split("-");
+
+		/*
+		 * A chain that starts with present QSOs has to end with a present run,
+		 * so its length is odd. A chain that starts with missing QSOs needs an
+		 * even length for the same reason.
+		 */
+		if (startsPresent) {
+			if (runLengths.length % 2 == 0) {
+				return null;
+			}
+		} else if (runLengths.length % 2 == 1 || runLengths.length < 2) {
+			return null;
+		}
+
+		List<WinTestLogSegment> parsedSegments = new ArrayList<>();
+		long cursor = firstRow;
+		boolean present = startsPresent;
+
+		for (String runLength : runLengths) {
+			long count = parseUnsignedValue(runLength);
+			if (count < 0L) {
+				return null;
+			}
+
+			if (present && count > 0L) {
+				if (parsedSegments.size() >= MAX_SEGMENTS) {
+					return null;
+				}
+				parsedSegments.add(new WinTestLogSegment(cursor, cursor + count - 1L));
+			}
+
+			cursor += count;
+			present = !present;
+		}
+
+		return parsedSegments;
+	}
+
+	private static long parseUnsignedValue(String rawValue) {
+		if (rawValue == null) {
+			return -1L;
+		}
+
+		try {
+			return Long.parseLong(rawValue.trim());
+		} catch (NumberFormatException exception) {
+			return -1L;
+		}
+	}
+
+	/**
+	 * @return log identity in the form {@code StationName@LogUniqueID}
+	 */
+	public String getLogId() {
+		return logId;
+	}
+
+	public Origin getOrigin() {
+		return origin;
+	}
+
+	/**
+	 * @return ranges of QSO numbers the announcing station holds
+	 */
+	public List<WinTestLogSegment> getSegments() {
+		return Collections.unmodifiableList(segments);
+	}
+
+	/**
+	 * @return highest announced QSO number, or {@code 0} for an empty inventory
+	 */
+	public long getHighestQsoNumber() {
+		long highestQsoNumber = 0L;
+		for (WinTestLogSegment segment : segments) {
+			if (segment.getCountTo() > highestQsoNumber) {
+				highestQsoNumber = segment.getCountTo();
+			}
+		}
+		return highestQsoNumber;
+	}
+
+	@Override
+	public String toString() {
+		return logId + " " + origin + " " + segments;
+	}
+}

src/main/java/kst4contest/controller/WinTestLogSegment.java

@@ -0,0 +1,60 @@
+package kst4contest.controller;
+
+/**
+ * Consecutive range of Win-Test QSO numbers inside one log.
+ *
+ * <p>Win-Test numbers the QSOs of every log continuously. The {@code IHAVE}
+ * inventory of a log is therefore expressed as a list of ranges that are
+ * present in that log. A range is inclusive on both ends.</p>
+ */
+public final class WinTestLogSegment {
+
+	private final long countFrom;
+	private final long countTo;
+
+	/**
+	 * @param countFrom first QSO number of the range
+	 * @param countTo last QSO number of the range
+	 */
+	public WinTestLogSegment(long countFrom, long countTo) {
+		this.countFrom = countFrom;
+		this.countTo = countTo;
+	}
+
+	public long getCountFrom() {
+		return countFrom;
+	}
+
+	public long getCountTo() {
+		return countTo;
+	}
+
+	/**
+	 * @return number of QSOs covered by this range, never negative
+	 */
+	public long getCount() {
+		return countTo < countFrom ? 0L : countTo - countFrom + 1L;
+	}
+
+	@Override
+	public boolean equals(Object other) {
+		if (this == other) {
+			return true;
+		}
+		if (!(other instanceof WinTestLogSegment)) {
+			return false;
+		}
+		WinTestLogSegment otherSegment = (WinTestLogSegment) other;
+		return countFrom == otherSegment.countFrom && countTo == otherSegment.countTo;
+	}
+
+	@Override
+	public int hashCode() {
+		return Long.hashCode(countFrom) * 31 + Long.hashCode(countTo);
+	}
+
+	@Override
+	public String toString() {
+		return countFrom + "-" + countTo;
+	}
+}

src/main/java/kst4contest/controller/WinTestLogSyncService.java

@@ -0,0 +1,611 @@
+package kst4contest.controller;
+
+import java.util.ArrayList;
+import java.util.HashMap;
+import java.util.LinkedHashMap;
+import java.util.List;
+import java.util.Map;
+import java.util.NavigableSet;
+import java.util.Optional;
+import java.util.TreeSet;
+import java.util.function.LongSupplier;
+import java.util.function.Supplier;
+
+/**
+ * Recovers the part of a Win-Test log that was written before KST4Contest was
+ * started.
+ *
+ * <p>Win-Test broadcasts every new QSO as an {@code ADDQSO} packet. A client
+ * that joins the network later never sees the QSOs logged before it started, so
+ * stations already worked would still be shown as not worked. Win-Test also
+ * offers a pull mechanism for exactly this situation, and this service is the
+ * port of the wtKST {@code WtLogSync} implementation of it:</p>
+ *
+ * <ol>
+ *     <li>a Win-Test station announces itself with {@code HELLO} or, if its log
+ *         was opened before we started listening, with its periodic
+ *         {@code STATUS};</li>
+ *     <li>its periodic {@code IHAVE} packets announce which QSO numbers of
+ *         which log it holds;</li>
+ *     <li>missing ranges are requested with {@code NEEDQSO}, at most
+ *         {@value #MAX_QSOS_PER_REQUEST} QSOs per request;</li>
+ *     <li>Win-Test answers with ordinary {@code ADDQSO} packets that are
+ *         addressed to us instead of being broadcast.</li>
+ * </ol>
+ *
+ * <p>Because the answers are ordinary {@code ADDQSO} packets, the recovered
+ * QSOs run through the same Worked handling as live QSOs. This service only
+ * decides what still has to be requested; it neither touches the database nor
+ * the user interface.</p>
+ *
+ * <p>If a station is known but no usable {@code IHAVE} inventory arrives within
+ * {@value #INVENTORY_GRACE_PERIOD_MS} ms, a blind fallback requests fixed
+ * blocks starting at QSO number one until a block stays unanswered. That covers
+ * Win-Test versions whose {@code IHAVE} format carries no run lengths.</p>
+ *
+ * <p>Deviation from wtKST: wtKST discards its whole QSO table whenever a
+ * {@code HELLO} arrives, because it displays that table. KST4Contest only
+ * accumulates Worked state, where a stale entry is harmless while a discarded
+ * one would cause the complete log to be requested and written again. The log
+ * identity {@code StationName@LogUniqueID} already changes when Win-Test opens
+ * a different log, so nothing is cleared here.</p>
+ */
+public class WinTestLogSyncService {
+
+	/** Win-Test answers at most this many QSOs for one NEEDQSO request. */
+	static final int MAX_QSOS_PER_REQUEST = 50;
+
+	/** Time after which an unanswered request is retried elsewhere. */
+	static final long REQUEST_TIMEOUT_MS = 5000L;
+
+	/** Shortest distance between two evaluations without a pending trigger. */
+	static final long TICK_INTERVAL_MS = 2000L;
+
+	/** Waiting time for a usable IHAVE before the blind fallback starts. */
+	static final long INVENTORY_GRACE_PERIOD_MS = 15000L;
+
+	/** Upper bound for the blind fallback, equals 10000 QSOs. */
+	static final int MAX_BLIND_BLOCKS = 200;
+
+	/** Guards the gap search against a corrupted inventory. */
+	private static final long MAX_SCANNED_QSO_NUMBERS = 200000L;
+
+	/**
+	 * Sends a NEEDQSO request to a Win-Test station.
+	 */
+	@FunctionalInterface
+	public interface NeedQsoSender {
+
+		/**
+		 * @param targetStation Win-Test station name the request is sent to
+		 * @param logId log identity in the form {@code StationName@LogUniqueID}
+		 * @param countFrom first requested QSO number
+		 * @param countTo last requested QSO number
+		 */
+		void sendNeedQso(String targetStation, String logId, long countFrom, long countTo);
+	}
+
+	/** Progress of the log recovery, used for status reporting. */
+	public enum SyncState {
+		/** No Win-Test station seen yet. */
+		IDLE,
+		/** A station is known, but nothing has been requested yet. */
+		STATION_DETECTED,
+		/** QSOs are being requested. */
+		SYNCING,
+		/** Everything announced by the known stations has been received. */
+		IN_SYNC
+	}
+
+	private final NeedQsoSender needQsoSender;
+	private final Supplier<String> ownStationNameSupplier;
+	private final LongSupplier clock;
+
+	/** Inventories per Win-Test station, keyed by log identity. */
+	private final Map<String, Map<String, WinTestIhaveInventory>> inventoriesByStation =
+			new LinkedHashMap<>();
+
+	/** QSO numbers already received, keyed by log identity. */
+	private final Map<String, NavigableSet<Long>> receivedQsoNumbersByLogId = new HashMap<>();
+
+	/** State of the blind fallback, keyed by log identity. */
+	private final Map<String, BlindScan> blindScansByLogId = new LinkedHashMap<>();
+
+	private PendingRequest pendingRequest;
+	private long firstStationSeenAtMs;
+	private boolean usableInventorySeen;
+	private long lastTickMs;
+	private boolean tickDueImmediately;
+	private SyncState state = SyncState.IDLE;
+
+	/**
+	 * @param needQsoSender transport used for NEEDQSO requests
+	 * @param ownStationNameSupplier own Win-Test station name, read late because
+	 *                               it can be changed in the settings at runtime
+	 */
+	public WinTestLogSyncService(
+			NeedQsoSender needQsoSender,
+			Supplier<String> ownStationNameSupplier
+	) {
+		this(needQsoSender, ownStationNameSupplier, System::currentTimeMillis);
+	}
+
+	/**
+	 * @param needQsoSender transport used for NEEDQSO requests
+	 * @param ownStationNameSupplier own Win-Test station name
+	 * @param clock time source in milliseconds
+	 */
+	WinTestLogSyncService(
+			NeedQsoSender needQsoSender,
+			Supplier<String> ownStationNameSupplier,
+			LongSupplier clock
+	) {
+		this.needQsoSender = needQsoSender;
+		this.ownStationNameSupplier = ownStationNameSupplier;
+		this.clock = clock;
+	}
+
+	/**
+	 * Registers a Win-Test station seen in a HELLO or STATUS packet.
+	 *
+	 * @param stationName Win-Test station name
+	 */
+	public synchronized void onStationSeen(String stationName) {
+		if (stationName == null || stationName.isBlank()) {
+			return;
+		}
+
+		String normalizedStationName = stationName.trim();
+		if (normalizedStationName.equalsIgnoreCase(resolveOwnStationName())) {
+			// our own packets, nothing to synchronize from
+			return;
+		}
+
+		if (inventoriesByStation.putIfAbsent(normalizedStationName, new LinkedHashMap<>()) == null) {
+			tickDueImmediately = true;
+		}
+
+		if (firstStationSeenAtMs == 0L) {
+			firstStationSeenAtMs = clock.getAsLong();
+		}
+
+		if (state == SyncState.IDLE) {
+			state = SyncState.STATION_DETECTED;
+		}
+	}
+
+	/**
+	 * Takes over the inventory of an IHAVE packet.
+	 *
+	 * @param packet received IHAVE packet
+	 */
+	public synchronized void onIhaveReceived(WinTestPacket packet) {
+		if (packet == null || !packet.isAddressedTo(resolveOwnStationName())) {
+			return;
+		}
+
+		Optional<WinTestIhaveInventory> parsedInventory = WinTestIhaveInventory.fromPacket(packet);
+		if (parsedInventory.isEmpty()) {
+			return;
+		}
+
+		WinTestIhaveInventory inventory = parsedInventory.get();
+		onStationSeen(packet.getSource());
+
+		Map<String, WinTestIhaveInventory> stationInventories =
+				inventoriesByStation.get(packet.getSource() == null ? "" : packet.getSource().trim());
+
+		if (stationInventories == null) {
+			return;
+		}
+
+		WinTestIhaveInventory previousInventory =
+				stationInventories.put(inventory.getLogId(), inventory);
+
+		if (previousInventory == null
+				|| !previousInventory.getSegments().equals(inventory.getSegments())) {
+			System.out.println("[WinTest LogSync] inventory of " + inventory.getLogId()
+					+ " from " + packet.getSource()
+					+ " (" + inventory.getOrigin() + "): " + inventory.getSegments());
+		}
+
+		usableInventorySeen = true;
+		blindScansByLogId.remove(inventory.getLogId());
+		tickDueImmediately = true;
+	}
+
+	/**
+	 * Registers a QSO received in an ADDQSO packet.
+	 *
+	 * @param logId log identity in the form {@code StationName@LogUniqueID}
+	 * @param qsoNumber Win-Test QSO number inside that log
+	 * @return {@code true} when this QSO was not known before, and therefore
+	 *         still has to be applied to Worked state and database
+	 */
+	public synchronized boolean registerReceivedQso(String logId, long qsoNumber) {
+		if (logId == null || logId.isBlank() || qsoNumber <= 0L) {
+			// without a usable identity the QSO cannot be deduplicated
+			return true;
+		}
+
+		NavigableSet<Long> receivedQsoNumbers =
+				receivedQsoNumbersByLogId.computeIfAbsent(logId.trim(), key -> new TreeSet<>());
+		boolean isNewQso = receivedQsoNumbers.add(qsoNumber);
+
+		if (pendingRequest != null
+				&& pendingRequest.logId.equals(logId.trim())
+				&& qsoNumber >= pendingRequest.countFrom
+				&& qsoNumber <= pendingRequest.countTo) {
+
+			pendingRequest.answeredQsoCount++;
+
+			if (qsoNumber == pendingRequest.countTo
+					|| pendingRequest.answeredQsoCount >= pendingRequest.getRequestedQsoCount()) {
+				PendingRequest completedRequest = pendingRequest;
+				pendingRequest = null;
+				if (completedRequest.blind) {
+					finishBlindBlock(completedRequest);
+				}
+				tickDueImmediately = true;
+			}
+		}
+
+		return isNewQso;
+	}
+
+	/**
+	 * Advances the recovery. Called after every received packet and on every
+	 * receive timeout of the listener; an internal interval keeps the actual
+	 * work rare while a satisfied request triggers the next one immediately.
+	 */
+	public synchronized void tick() {
+		long now = clock.getAsLong();
+
+		if (!tickDueImmediately && now - lastTickMs < TICK_INTERVAL_MS) {
+			return;
+		}
+
+		lastTickMs = now;
+		tickDueImmediately = false;
+
+		if (pendingRequest != null) {
+			if (now - pendingRequest.sentAtMs < REQUEST_TIMEOUT_MS) {
+				return;
+			}
+			handlePendingTimeout();
+			return;
+		}
+
+		if (requestNextMissingRange(now)) {
+			return;
+		}
+
+		if (requestNextBlindBlock(now)) {
+			return;
+		}
+
+		if (state == SyncState.SYNCING) {
+			state = SyncState.IN_SYNC;
+		}
+	}
+
+	/**
+	 * @return current progress of the recovery
+	 */
+	public synchronized SyncState getState() {
+		return state;
+	}
+
+	/**
+	 * @return number of QSO numbers known for the given log
+	 */
+	synchronized int getKnownQsoCount(String logId) {
+		NavigableSet<Long> receivedQsoNumbers = receivedQsoNumbersByLogId.get(logId);
+		return receivedQsoNumbers == null ? 0 : receivedQsoNumbers.size();
+	}
+
+	private void handlePendingTimeout() {
+		PendingRequest timedOutRequest = pendingRequest;
+		pendingRequest = null;
+
+		if (timedOutRequest.blind) {
+			finishBlindBlock(timedOutRequest);
+			return;
+		}
+
+		String alternativeStation =
+				findAlternativeStation(timedOutRequest.logId, timedOutRequest.targetStation);
+
+		System.out.println("[WinTest LogSync] no answer from " + timedOutRequest.targetStation
+				+ " for " + timedOutRequest.logId + " "
+				+ timedOutRequest.countFrom + "-" + timedOutRequest.countTo);
+
+		if (alternativeStation != null) {
+			sendRequest(
+					alternativeStation,
+					timedOutRequest.logId,
+					timedOutRequest.countFrom,
+					timedOutRequest.countTo,
+					false,
+					clock.getAsLong()
+			);
+			return;
+		}
+
+		/*
+		 * Nobody else holds this log. The silent station is dropped and returns
+		 * with its next STATUS or IHAVE packet.
+		 */
+		System.out.println("[WinTest LogSync] dropping silent station "
+				+ timedOutRequest.targetStation + ", waiting for its next STATUS or IHAVE");
+		inventoriesByStation.remove(timedOutRequest.targetStation);
+		tickDueImmediately = true;
+	}
+
+	private String findAlternativeStation(String logId, String excludedStation) {
+		for (Map.Entry<String, Map<String, WinTestIhaveInventory>> station
+				: inventoriesByStation.entrySet()) {
+
+			if (station.getKey().equals(excludedStation)) {
+				continue;
+			}
+			if (station.getValue().containsKey(logId)) {
+				return station.getKey();
+			}
+		}
+		return null;
+	}
+
+	/**
+	 * Looks for the first announced QSO range that is still missing and
+	 * requests it. Stations that own a log are preferred over stations that
+	 * only mirror it.
+	 *
+	 * @param now current time in milliseconds
+	 * @return {@code true} when a request was sent
+	 */
+	private boolean requestNextMissingRange(long now) {
+		for (int pass = 0; pass < 2; pass++) {
+			boolean preferOwner = pass == 0;
+
+			for (Map.Entry<String, Map<String, WinTestIhaveInventory>> station
+					: new ArrayList<>(inventoriesByStation.entrySet())) {
+
+				for (WinTestIhaveInventory inventory : new ArrayList<>(station.getValue().values())) {
+					boolean isOwner = inventory.getOrigin() == WinTestIhaveInventory.Origin.OWNER;
+					if (preferOwner != isOwner) {
+						continue;
+					}
+
+					long[] missingRange = findMissingRange(
+							inventory.getSegments(),
+							receivedQsoNumbersByLogId.get(inventory.getLogId())
+					);
+
+					if (missingRange == null) {
+						continue;
+					}
+
+					sendRequest(
+							station.getKey(),
+							inventory.getLogId(),
+							missingRange[0],
+							missingRange[1],
+							false,
+							now
+					);
+					return true;
+				}
+			}
+		}
+		return false;
+	}
+
+	/**
+	 * Determines the next missing QSO range of one log.
+	 *
+	 * <p>wtKST compares its own segment list against the announced one and
+	 * derives the request bounds from the segment indices. Searching the gap
+	 * directly produces the same ranges for the ordinary cases, cannot run past
+	 * the end of either list, and never asks for QSO numbers that are already
+	 * known.</p>
+	 *
+	 * @param segments ranges announced by the station
+	 * @param receivedQsoNumbers QSO numbers already received for this log
+	 * @return first missing range as {@code {countFrom, countTo}}, or
+	 *         {@code null} when nothing is missing
+	 */
+	static long[] findMissingRange(
+			List<WinTestLogSegment> segments,
+			NavigableSet<Long> receivedQsoNumbers
+	) {
+		if (segments == null) {
+			return null;
+		}
+
+		long remainingScanBudget = MAX_SCANNED_QSO_NUMBERS;
+
+		for (WinTestLogSegment segment : segments) {
+			for (long qsoNumber = segment.getCountFrom();
+					qsoNumber <= segment.getCountTo();
+					qsoNumber++) {
+
+				remainingScanBudget--;
+				if (remainingScanBudget < 0L) {
+					return null;
+				}
+
+				if (receivedQsoNumbers != null && receivedQsoNumbers.contains(qsoNumber)) {
+					continue;
+				}
+
+				long countFrom = qsoNumber;
+				long countTo = countFrom;
+
+				while (countTo < segment.getCountTo()
+						&& countTo - countFrom + 1L < MAX_QSOS_PER_REQUEST
+						&& (receivedQsoNumbers == null || !receivedQsoNumbers.contains(countTo + 1L))) {
+					countTo++;
+				}
+
+				return new long[] { countFrom, countTo };
+			}
+		}
+
+		return null;
+	}
+
+	/**
+	 * Requests the next fixed block of a log whose station never sent a usable
+	 * inventory.
+	 *
+	 * @param now current time in milliseconds
+	 * @return {@code true} when a request was sent
+	 */
+	private boolean requestNextBlindBlock(long now) {
+		if (usableInventorySeen || firstStationSeenAtMs == 0L) {
+			return false;
+		}
+		if (now - firstStationSeenAtMs < INVENTORY_GRACE_PERIOD_MS) {
+			return false;
+		}
+
+		for (String logId : new ArrayList<>(receivedQsoNumbersByLogId.keySet())) {
+			BlindScan blindScan = blindScansByLogId.computeIfAbsent(logId, key -> new BlindScan());
+
+			if (blindScan.completed || blindScan.requestedBlockCount >= MAX_BLIND_BLOCKS) {
+				continue;
+			}
+
+			String targetStation = resolveStationForLogId(logId);
+			if (targetStation == null) {
+				continue;
+			}
+
+			blindScan.requestedBlockCount++;
+			sendRequest(
+					targetStation,
+					logId,
+					blindScan.nextCountFrom,
+					blindScan.nextCountFrom + MAX_QSOS_PER_REQUEST - 1L,
+					true,
+					now
+			);
+			return true;
+		}
+
+		return false;
+	}
+
+	private void finishBlindBlock(PendingRequest finishedRequest) {
+		BlindScan blindScan = blindScansByLogId.get(finishedRequest.logId);
+		if (blindScan == null) {
+			return;
+		}
+
+		System.out.println("[WinTest LogSync] blind block " + finishedRequest.countFrom
+				+ "-" + finishedRequest.countTo + " of " + finishedRequest.logId
+				+ " answered with " + finishedRequest.answeredQsoCount + " QSOs");
+
+		if (finishedRequest.answeredQsoCount == 0) {
+			// the log ends before this block, nothing left to fetch
+			blindScan.completed = true;
+		} else {
+			blindScan.nextCountFrom = finishedRequest.countTo + 1L;
+		}
+
+		tickDueImmediately = true;
+	}
+
+	/**
+	 * Resolves the Win-Test station a log belongs to. The log identity carries
+	 * the owning station name in front of the {@code @} separator.
+	 *
+	 * @param logId log identity
+	 * @return station name to ask, or {@code null} when none is known
+	 */
+	private String resolveStationForLogId(String logId) {
+		int separatorIndex = logId.indexOf('@');
+		String ownerStationName = separatorIndex > 0 ? logId.substring(0, separatorIndex) : logId;
+
+		for (String stationName : inventoriesByStation.keySet()) {
+			if (stationName.equalsIgnoreCase(ownerStationName)) {
+				return stationName;
+			}
+		}
+
+		return ownerStationName.isBlank() ? null : ownerStationName;
+	}
+
+	private void sendRequest(
+			String targetStation,
+			String logId,
+			long countFrom,
+			long countTo,
+			boolean blind,
+			long now
+	) {
+		pendingRequest = new PendingRequest(targetStation, logId, countFrom, countTo, blind, now);
+		state = SyncState.SYNCING;
+
+		try {
+			needQsoSender.sendNeedQso(targetStation, logId, countFrom, countTo);
+		} catch (RuntimeException exception) {
+			/*
+			 * A failed transmission must not stop the receive loop. The pending
+			 * request runs into its timeout and is retried from there.
+			 */
+			System.out.println(
+					"[WinTest LogSync] NEEDQSO could not be sent: " + exception.getMessage()
+			);
+		}
+	}
+
+	private String resolveOwnStationName() {
+		if (ownStationNameSupplier == null) {
+			return "";
+		}
+
+		String ownStationName = ownStationNameSupplier.get();
+		return ownStationName == null ? "" : ownStationName.trim();
+	}
+
+	/** Request that is waiting for its answer. */
+	private static final class PendingRequest {
+
+		private final String targetStation;
+		private final String logId;
+		private final long countFrom;
+		private final long countTo;
+		private final boolean blind;
+		private final long sentAtMs;
+		private int answeredQsoCount;
+
+		private PendingRequest(
+				String targetStation,
+				String logId,
+				long countFrom,
+				long countTo,
+				boolean blind,
+				long sentAtMs
+		) {
+			this.targetStation = targetStation;
+			this.logId = logId;
+			this.countFrom = countFrom;
+			this.countTo = countTo;
+			this.blind = blind;
+			this.sentAtMs = sentAtMs;
+		}
+
+		private long getRequestedQsoCount() {
+			return countTo - countFrom + 1L;
+		}
+	}
+
+	/** Progress of the blind fallback for one log. */
+	private static final class BlindScan {
+		private long nextCountFrom = 1L;
+		private int requestedBlockCount;
+		private boolean completed;
+	}
+}

src/main/java/kst4contest/controller/WinTestMessage.java

@@ -17,8 +17,10 @@ import java.nio.charset.StandardCharsets;
  */
 public class WinTestMessage {
 
-    /** Win-Test message types relevant for SKED management. */
+    /** Win-Test message types sent by KST4Contest. */
     public enum MessageType {
+        /** Requests a range of QSOs of one Win-Test log for log synchronization. */
+        NEEDQSO,
         LOCKSKED,
         UNLOCKSKED,
         ADDSKED,

src/main/java/kst4contest/controller/WinTestNetworkAddressResolver.java

@@ -0,0 +1,227 @@
+package kst4contest.controller;
+
+import java.net.Inet4Address;
+import java.net.InetAddress;
+import java.net.InterfaceAddress;
+import java.net.NetworkInterface;
+import java.net.SocketException;
+import java.net.UnknownHostException;
+import java.util.Enumeration;
+
+/**
+ * Determines the broadcast address used to talk to the Win-Test network.
+ *
+ * <p>Win-Test only reacts to broadcast packets; a unicast request to the same
+ * station stays unanswered. The configured broadcast address is therefore the
+ * one setting that silently disables every outgoing Win-Test feature when it is
+ * wrong: sending to an address outside the local networks succeeds without an
+ * error and the packet is routed away.</p>
+ *
+ * <p>Incoming Win-Test packets carry the information that is actually needed.
+ * The source address of a received packet identifies the network the station
+ * lives in, so the broadcast address of the matching local interface reaches it
+ * reliably. The configured address remains the fallback and keeps working for a
+ * station behind a router, where no local interface matches.</p>
+ */
+public class WinTestNetworkAddressResolver {
+
+	/** Last resort when neither a station nor a usable setting is available. */
+	private static final String LIMITED_BROADCAST_ADDRESS = "255.255.255.255";
+
+	/**
+	 * Resolves the local broadcast address for a remote address.
+	 */
+	@FunctionalInterface
+	public interface LocalBroadcastLookup {
+
+		/**
+		 * @param remoteAddress address a Win-Test packet was received from
+		 * @return broadcast address of the matching local interface, or
+		 *         {@code null} when no local interface serves that network
+		 */
+		InetAddress findBroadcastFor(InetAddress remoteAddress);
+	}
+
+	private final LocalBroadcastLookup localBroadcastLookup;
+
+	private volatile InetAddress lastStationAddress;
+
+	private volatile String lastReportedBroadcastAddress;
+
+	public WinTestNetworkAddressResolver() {
+		this(WinTestNetworkAddressResolver::findLocalBroadcastAddress);
+	}
+
+	/**
+	 * @param localBroadcastLookup interface lookup, replaceable for tests
+	 */
+	WinTestNetworkAddressResolver(LocalBroadcastLookup localBroadcastLookup) {
+		this.localBroadcastLookup = localBroadcastLookup;
+	}
+
+	/**
+	 * Remembers where Win-Test packets come from.
+	 *
+	 * <p>Only addresses of real Win-Test stations may be passed in. Loopback and
+	 * wildcard addresses are ignored, so an internal control packet cannot
+	 * redirect outgoing Win-Test traffic.</p>
+	 *
+	 * @param stationAddress source address of a received Win-Test packet
+	 */
+	public void rememberStationAddress(InetAddress stationAddress) {
+		if (stationAddress == null
+				|| stationAddress.isLoopbackAddress()
+				|| stationAddress.isAnyLocalAddress()
+				|| !(stationAddress instanceof Inet4Address)) {
+			return;
+		}
+
+		this.lastStationAddress = stationAddress;
+	}
+
+	/**
+	 * Determines the broadcast address for outgoing Win-Test packets.
+	 *
+	 * <p>Order of preference: the broadcast address of the local interface that
+	 * serves the last seen Win-Test station, then the configured address, then
+	 * the limited broadcast address.</p>
+	 *
+	 * @param configuredBroadcastAddress address from the settings, may be blank
+	 * @return address to send Win-Test packets to
+	 * @throws UnknownHostException if the configured address cannot be resolved
+	 *                              and the limited broadcast address fails too
+	 */
+	public InetAddress resolveBroadcastAddress(String configuredBroadcastAddress)
+			throws UnknownHostException {
+
+		InetAddress stationAddress = this.lastStationAddress;
+
+		if (stationAddress != null) {
+			InetAddress derivedBroadcastAddress =
+					localBroadcastLookup.findBroadcastFor(stationAddress);
+
+			if (derivedBroadcastAddress != null) {
+				reportDerivedAddress(derivedBroadcastAddress, configuredBroadcastAddress);
+				return derivedBroadcastAddress;
+			}
+		}
+
+		if (configuredBroadcastAddress != null && !configuredBroadcastAddress.isBlank()) {
+			return InetAddress.getByName(configuredBroadcastAddress.trim());
+		}
+
+		return InetAddress.getByName(LIMITED_BROADCAST_ADDRESS);
+	}
+
+	/**
+	 * Logs a derived address once as long as it stays the same, and points out
+	 * a configured address that does not match the Win-Test network.
+	 */
+	private void reportDerivedAddress(
+			InetAddress derivedBroadcastAddress,
+			String configuredBroadcastAddress
+	) {
+		String derivedHostAddress = derivedBroadcastAddress.getHostAddress();
+
+		if (derivedHostAddress.equals(lastReportedBroadcastAddress)) {
+			return;
+		}
+
+		lastReportedBroadcastAddress = derivedHostAddress;
+
+		String configuredHostAddress = configuredBroadcastAddress == null
+				? "" : configuredBroadcastAddress.trim();
+
+		if (derivedHostAddress.equals(configuredHostAddress)) {
+			return;
+		}
+
+		System.out.println("[WinTest] using broadcast address " + derivedHostAddress
+				+ " of the network Win-Test was heard on, configured is '"
+				+ configuredHostAddress + "'");
+	}
+
+	/**
+	 * Searches the local interfaces for the network a remote address belongs to.
+	 *
+	 * @param remoteAddress address of a Win-Test station
+	 * @return broadcast address of the matching interface, or {@code null}
+	 */
+	static InetAddress findLocalBroadcastAddress(InetAddress remoteAddress) {
+		if (!(remoteAddress instanceof Inet4Address)) {
+			return null;
+		}
+
+		try {
+			Enumeration<NetworkInterface> networkInterfaces =
+					NetworkInterface.getNetworkInterfaces();
+
+			while (networkInterfaces != null && networkInterfaces.hasMoreElements()) {
+				NetworkInterface networkInterface = networkInterfaces.nextElement();
+
+				for (InterfaceAddress interfaceAddress : networkInterface.getInterfaceAddresses()) {
+					InetAddress broadcastAddress = interfaceAddress.getBroadcast();
+
+					if (broadcastAddress == null
+							|| !(interfaceAddress.getAddress() instanceof Inet4Address)) {
+						continue;
+					}
+
+					if (isInSameSubnet(
+							interfaceAddress.getAddress(),
+							remoteAddress,
+							interfaceAddress.getNetworkPrefixLength())) {
+						return broadcastAddress;
+					}
+				}
+			}
+		} catch (SocketException exception) {
+			System.out.println("[WinTest] could not inspect local interfaces: "
+					+ exception.getMessage());
+		}
+
+		return null;
+	}
+
+	/**
+	 * Compares two IPv4 addresses up to the given network prefix length.
+	 *
+	 * @param localAddress address of a local interface
+	 * @param remoteAddress address of the Win-Test station
+	 * @param networkPrefixLength prefix length of the local interface
+	 * @return {@code true} when both addresses share the same network
+	 */
+	static boolean isInSameSubnet(
+			InetAddress localAddress,
+			InetAddress remoteAddress,
+			int networkPrefixLength
+	) {
+		if (localAddress == null || remoteAddress == null) {
+			return false;
+		}
+
+		byte[] localBytes = localAddress.getAddress();
+		byte[] remoteBytes = remoteAddress.getAddress();
+
+		if (localBytes.length != remoteBytes.length
+				|| networkPrefixLength < 0
+				|| networkPrefixLength > localBytes.length * 8) {
+			return false;
+		}
+
+		int remainingPrefixBits = networkPrefixLength;
+
+		for (int byteIndex = 0; byteIndex < localBytes.length && remainingPrefixBits > 0; byteIndex++) {
+			int comparedBits = Math.min(8, remainingPrefixBits);
+			int mask = (0xFF << (8 - comparedBits)) & 0xFF;
+
+			if ((localBytes[byteIndex] & mask) != (remoteBytes[byteIndex] & mask)) {
+				return false;
+			}
+
+			remainingPrefixBits -= comparedBits;
+		}
+
+		return true;
+	}
+}

src/main/java/kst4contest/controller/WinTestPacket.java

@@ -0,0 +1,238 @@
+package kst4contest.controller;
+
+import java.nio.charset.StandardCharsets;
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.List;
+import java.util.regex.Matcher;
+import java.util.regex.Pattern;
+
+/**
+ * Win-Test network packet received over UDP.
+ *
+ * <p>This is the receiving counterpart of {@link WinTestMessage} and follows the
+ * same framing:</p>
+ *
+ * <pre>
+ *   MESSAGETYPE: "src" "dst" data{checksum}\0
+ * </pre>
+ *
+ * <p>The checksum byte always has bit 7 set and is therefore not valid ASCII.
+ * Decoding the datagram as text before removing it turns the byte into a
+ * replacement character that sticks to the last data field. That is harmless
+ * for fields KST4Contest never reads, but the log synchronization needs exactly
+ * those trailing fields: the log ID of an {@code ADDQSO} packet and the
+ * run-length inventory of an {@code IHAVE} packet. The framing is therefore
+ * resolved on the raw bytes here, once, before any text parsing.</p>
+ */
+public final class WinTestPacket {
+
+	/** Quoted values stay one token, unquoted values are split at whitespace. */
+	private static final Pattern TOKEN_PATTERN = Pattern.compile("\"([^\"]*)\"|(\\S+)");
+
+	private final String messageType;
+	private final String source;
+	private final String destination;
+	private final String messageText;
+	private final List<String> dataTokens;
+	private final boolean checksumPresent;
+	private final boolean checksumValid;
+
+	private WinTestPacket(
+			String messageType,
+			String source,
+			String destination,
+			String messageText,
+			List<String> dataTokens,
+			boolean checksumPresent,
+			boolean checksumValid
+	) {
+		this.messageType = messageType;
+		this.source = source;
+		this.destination = destination;
+		this.messageText = messageText;
+		this.dataTokens = dataTokens;
+		this.checksumPresent = checksumPresent;
+		this.checksumValid = checksumValid;
+	}
+
+	/**
+	 * Builds a packet from a received datagram.
+	 *
+	 * <p>Trailing NUL bytes are removed first. If the resulting last byte has
+	 * bit 7 set it is the Win-Test checksum: it is verified against the sum of
+	 * all preceding bytes and removed before the message text is decoded.</p>
+	 *
+	 * @param datagram raw datagram buffer
+	 * @param length number of valid bytes in the buffer
+	 * @return parsed packet, or {@code null} when the datagram carries no message
+	 */
+	public static WinTestPacket fromDatagram(byte[] datagram, int length) {
+		if (datagram == null || length <= 0 || length > datagram.length) {
+			return null;
+		}
+
+		int endIndex = length;
+		while (endIndex > 0 && datagram[endIndex - 1] == 0) {
+			endIndex--;
+		}
+
+		if (endIndex == 0) {
+			return null;
+		}
+
+		boolean hasChecksum = (datagram[endIndex - 1] & 0x80) != 0;
+		boolean isChecksumValid = false;
+		int textEndIndex = endIndex;
+
+		if (hasChecksum) {
+			int sum = 0;
+			for (int index = 0; index < endIndex - 1; index++) {
+				sum += datagram[index] & 0xFF;
+			}
+			byte expectedChecksum = (byte) ((sum | 0x80) & 0xFF);
+			isChecksumValid = expectedChecksum == datagram[endIndex - 1];
+			textEndIndex = endIndex - 1;
+		}
+
+		String text = new String(datagram, 0, textEndIndex, StandardCharsets.US_ASCII);
+		return fromMessageText(text, hasChecksum, isChecksumValid);
+	}
+
+	/**
+	 * Builds a packet from an already decoded message text without checksum
+	 * information. Used for messages that reach the listener as text.
+	 *
+	 * @param messageText complete message text
+	 * @return parsed packet, or {@code null} for an unusable message
+	 */
+	public static WinTestPacket fromMessageText(String messageText) {
+		return fromMessageText(messageText, false, false);
+	}
+
+	private static WinTestPacket fromMessageText(
+			String rawMessageText,
+			boolean checksumPresent,
+			boolean checksumValid
+	) {
+		if (rawMessageText == null) {
+			return null;
+		}
+
+		String text = rawMessageText.trim();
+		int typeEndIndex = text.indexOf(": ");
+		if (typeEndIndex <= 0) {
+			return null;
+		}
+
+		String type = text.substring(0, typeEndIndex);
+		List<String> tokens = tokenize(text.substring(typeEndIndex + 2));
+
+		String packetSource = tokens.isEmpty() ? "" : tokens.get(0);
+		String packetDestination = tokens.size() > 1 ? tokens.get(1) : "";
+		List<String> data = tokens.size() > 2
+				? new ArrayList<>(tokens.subList(2, tokens.size()))
+				: new ArrayList<>();
+
+		return new WinTestPacket(
+				type,
+				packetSource,
+				packetDestination,
+				text,
+				data,
+				checksumPresent,
+				checksumValid
+		);
+	}
+
+	/**
+	 * Splits Win-Test payload text into fields. Quoted values are kept together
+	 * and empty quoted values are preserved, so field positions stay stable.
+	 *
+	 * @param text payload text
+	 * @return field values without their surrounding quotes
+	 */
+	static List<String> tokenize(String text) {
+		List<String> tokens = new ArrayList<>();
+		if (text == null) {
+			return tokens;
+		}
+
+		Matcher matcher = TOKEN_PATTERN.matcher(text);
+		while (matcher.find()) {
+			tokens.add(matcher.group(1) != null ? matcher.group(1) : matcher.group(2));
+		}
+		return tokens;
+	}
+
+	/**
+	 * @return message type such as {@code ADDQSO}, never {@code null}
+	 */
+	public String getMessageType() {
+		return messageType;
+	}
+
+	/**
+	 * @return Win-Test station that sent the packet
+	 */
+	public String getSource() {
+		return source;
+	}
+
+	/**
+	 * @return addressed Win-Test station, empty for a broadcast
+	 */
+	public String getDestination() {
+		return destination;
+	}
+
+	/**
+	 * @return complete message text without checksum byte and NUL terminator
+	 */
+	public String getMessageText() {
+		return messageText;
+	}
+
+	/**
+	 * @return payload fields following source and destination
+	 */
+	public List<String> getDataTokens() {
+		return Collections.unmodifiableList(dataTokens);
+	}
+
+	/**
+	 * @param index payload field position
+	 * @return field value, or {@code null} when the field is missing
+	 */
+	public String getDataToken(int index) {
+		return index >= 0 && index < dataTokens.size() ? dataTokens.get(index) : null;
+	}
+
+	public boolean isChecksumPresent() {
+		return checksumPresent;
+	}
+
+	public boolean isChecksumValid() {
+		return checksumValid;
+	}
+
+	/**
+	 * Checks whether this packet is meant for us.
+	 *
+	 * @param ownStationName own Win-Test station name
+	 * @return {@code true} for a broadcast or for a packet addressed to us
+	 */
+	public boolean isAddressedTo(String ownStationName) {
+		if (destination == null || destination.isEmpty()) {
+			return true;
+		}
+		return ownStationName != null && destination.equalsIgnoreCase(ownStationName.trim());
+	}
+
+	@Override
+	public String toString() {
+		return messageType + ": src=" + source + " dst=" + destination
+				+ " fields=" + dataTokens.size()
+				+ (checksumPresent ? (checksumValid ? " checksum=ok" : " checksum=bad") : " checksum=none");
+	}
+}

src/main/java/kst4contest/model/ChatPreferences.java

@@ -148,7 +148,7 @@ public class ChatPreferences {
 	 *
 	 */
 
-	String programVersion = "Chat is powered by ON4KST \n\nUsage is free. You are welcome to support: \n\n- my project (donations, bugreports, good ideas are welcome), \n- ON4KST Servers, \n- AirScout developers and \n- OV3T (best AS-data provider of the world). \n\n73 de DO5AMF, Marc (DM5M / DARC X08)";
+	String programVersion = "Chat is powered by ON4KST \n\nUsage is free. You are welcome to support: \n\n- my project (donations, bugreports, good ideas are welcome), \n- ON4KST Servers, \n- AirScout developers and \n- OV3T (best AS-data provider of the world). \n\n73 de DO5AMF, Marc (DM5M / DARC X08)\nand DN9APW, Philipp Wagner";
 	String logsynch_storeWorkedCallSignsFileNameUDPMessageBackup = "udpReaderBackup.txt";
 	String storeAndRestorePreferencesFileName = ApplicationFileUtils.getFilePath(ApplicationConstants.APPLICATION_NAME, PREFERENCES_FILE);
 	String chatState; // working variable only for use by primarystage (title bar)

src/main/java/kst4contest/view/Kst4ContestApplication.java

@@ -5753,7 +5753,8 @@ public class Kst4ContestApplication extends Application implements StatusUpdateL
 				Alert a = new Alert(AlertType.INFORMATION);
 
 				a.setTitle("About kst4contest");
-				a.setHeaderText("kst4Contest " + ApplicationConstants.APPLICATION_CURRENT_VERSION + ": ON4KST Chatclient by DO5AMF");
+				a.setHeaderText("kst4Contest " + ApplicationConstants.APPLICATION_CURRENT_VERSION
+						+ ": ON4KST Chatclient by DO5AMF and DN9APW");
 				a.setContentText(chatcontroller.getChatPreferences().getProgramVersion());
 				a.show();
 			}

src/test/java/kst4contest/controller/WinTestIhaveInventoryTest.java

@@ -0,0 +1,71 @@
+package kst4contest.controller;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+
+import java.util.List;
+import java.util.Optional;
+
+import org.junit.jupiter.api.Test;
+
+class WinTestIhaveInventoryTest {
+
+	private static Optional<WinTestIhaveInventory> parse(String messageText) {
+		return WinTestIhaveInventory.fromPacket(WinTestPacket.fromMessageText(messageText));
+	}
+
+	@Test
+	void inventoryStartingWithPresentQsosIsExpanded() {
+		Optional<WinTestIhaveInventory> inventory =
+				parse("IHAVE: \"STN1\" \"\" \"STN1@9\" E 1 1 911-1-117");
+
+		assertTrue(inventory.isPresent());
+		assertEquals("STN1@9", inventory.get().getLogId());
+		assertEquals(WinTestIhaveInventory.Origin.LOGGED_ELSE, inventory.get().getOrigin());
+		assertEquals(
+				List.of(new WinTestLogSegment(1L, 911L), new WinTestLogSegment(913L, 1029L)),
+				inventory.get().getSegments());
+		assertEquals(1029L, inventory.get().getHighestQsoNumber());
+	}
+
+	@Test
+	void inventoryStartingWithMissingQsosIsExpanded() {
+		Optional<WinTestIhaveInventory> inventory =
+				parse("IHAVE: \"STN1\" \"\" \"STN1@9\" O 1 0 30-5");
+
+		assertTrue(inventory.isPresent());
+		assertEquals(WinTestIhaveInventory.Origin.OWNER, inventory.get().getOrigin());
+		assertEquals(List.of(new WinTestLogSegment(31L, 35L)), inventory.get().getSegments());
+	}
+
+	@Test
+	void splitInventoryStartsAtItsFirstRow() {
+		/*
+		 * Win-Test splits long inventories. The documented example "100 1 10-5-5"
+		 * means: ten QSOs from 100, five missing, five present again.
+		 */
+		Optional<WinTestIhaveInventory> inventory =
+				parse("IHAVE: \"STN1\" \"\" \"STN1@9\" O 100 1 10-5-5");
+
+		assertTrue(inventory.isPresent());
+		assertEquals(
+				List.of(new WinTestLogSegment(100L, 109L), new WinTestLogSegment(115L, 119L)),
+				inventory.get().getSegments());
+	}
+
+	@Test
+	void runLengthChainWithWrongParityIsRejected() {
+		assertTrue(parse("IHAVE: \"STN1\" \"\" \"STN1@9\" O 1 1 10-5").isEmpty());
+		assertTrue(parse("IHAVE: \"STN1\" \"\" \"STN1@9\" O 1 0 10-5-5").isEmpty());
+	}
+
+	@Test
+	void legacyInventoryWithoutRunLengthsIsRejected() {
+		assertTrue(parse("IHAVE: \"STN1\" \"\" \"STN1@169\" \"OWNER\" 2").isEmpty());
+	}
+
+	@Test
+	void otherMessageTypesAreRejected() {
+		assertTrue(parse("STATUS: \"STN1\" \"\" 0 12 0 0 0 1443210 0").isEmpty());
+	}
+}

src/test/java/kst4contest/controller/WinTestLogSyncServiceTest.java

@@ -0,0 +1,171 @@
+package kst4contest.controller;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertFalse;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+
+import java.util.ArrayList;
+import java.util.List;
+
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+
+class WinTestLogSyncServiceTest {
+
+	private static final String LOG_ID = "STN1@44510";
+
+	private final List<String> sentRequests = new ArrayList<>();
+
+	private long currentTimeMs = 1_000_000L;
+
+	private WinTestLogSyncService service;
+
+	@BeforeEach
+	void createService() {
+		sentRequests.clear();
+		service = new WinTestLogSyncService(
+				(targetStation, logId, countFrom, countTo) ->
+						sentRequests.add(targetStation + " " + logId + " " + countFrom + "-" + countTo),
+				() -> "KST4Contest",
+				() -> currentTimeMs
+		);
+	}
+
+	private void receiveIhave(String messageText) {
+		service.onIhaveReceived(WinTestPacket.fromMessageText(messageText));
+	}
+
+	private void receiveQsos(long countFrom, long countTo) {
+		for (long qsoNumber = countFrom; qsoNumber <= countTo; qsoNumber++) {
+			service.registerReceivedQso(LOG_ID, qsoNumber);
+		}
+	}
+
+	@Test
+	void firstBlockOfAnAnnouncedLogIsRequested() {
+		receiveIhave("IHAVE: \"STN1\" \"\" \"" + LOG_ID + "\" O 1 1 120");
+
+		service.tick();
+
+		assertEquals(List.of("STN1 " + LOG_ID + " 1-50"), sentRequests);
+		assertEquals(WinTestLogSyncService.SyncState.SYNCING, service.getState());
+	}
+
+	@Test
+	void answeredBlockTriggersTheNextBlockUntilTheLogIsComplete() {
+		receiveIhave("IHAVE: \"STN1\" \"\" \"" + LOG_ID + "\" O 1 1 120");
+
+		service.tick();
+		receiveQsos(1L, 50L);
+		service.tick();
+		receiveQsos(51L, 100L);
+		service.tick();
+		receiveQsos(101L, 120L);
+		service.tick();
+
+		assertEquals(
+				List.of(
+						"STN1 " + LOG_ID + " 1-50",
+						"STN1 " + LOG_ID + " 51-100",
+						"STN1 " + LOG_ID + " 101-120"
+				),
+				sentRequests);
+		assertEquals(WinTestLogSyncService.SyncState.IN_SYNC, service.getState());
+	}
+
+	@Test
+	void onlyMissingQsoNumbersAreRequested() {
+		receiveQsos(1L, 10L);
+		receiveQsos(21L, 30L);
+		receiveIhave("IHAVE: \"STN1\" \"\" \"" + LOG_ID + "\" O 1 1 30");
+
+		service.tick();
+
+		assertEquals(List.of("STN1 " + LOG_ID + " 11-20"), sentRequests);
+	}
+
+	@Test
+	void alreadyKnownQsoIsReportedAsKnown() {
+		assertTrue(service.registerReceivedQso(LOG_ID, 5L));
+		assertFalse(service.registerReceivedQso(LOG_ID, 5L));
+	}
+
+	@Test
+	void qsoWithoutUsableIdentityIsAlwaysTreatedAsNew() {
+		assertTrue(service.registerReceivedQso(null, 5L));
+		assertTrue(service.registerReceivedQso("", 5L));
+		assertTrue(service.registerReceivedQso(LOG_ID, 0L));
+	}
+
+	@Test
+	void unansweredRequestIsRepeatedAtAnotherStationHoldingTheSameLog() {
+		receiveIhave("IHAVE: \"STN1\" \"\" \"" + LOG_ID + "\" O 1 1 120");
+		receiveIhave("IHAVE: \"STN2\" \"\" \"" + LOG_ID + "\" E 1 1 120");
+
+		service.tick();
+		currentTimeMs += WinTestLogSyncService.REQUEST_TIMEOUT_MS;
+		service.tick();
+
+		assertEquals(
+				List.of("STN1 " + LOG_ID + " 1-50", "STN2 " + LOG_ID + " 1-50"),
+				sentRequests);
+	}
+
+	@Test
+	void silentStationIsDroppedWhenNobodyElseHoldsTheLog() {
+		receiveIhave("IHAVE: \"STN1\" \"\" \"" + LOG_ID + "\" O 1 1 120");
+
+		service.tick();
+		currentTimeMs += WinTestLogSyncService.REQUEST_TIMEOUT_MS;
+		service.tick();
+		currentTimeMs += WinTestLogSyncService.REQUEST_TIMEOUT_MS;
+		service.tick();
+
+		assertEquals(List.of("STN1 " + LOG_ID + " 1-50"), sentRequests);
+	}
+
+	@Test
+	void blindFallbackRequestsFixedBlocksWithoutInventory() {
+		service.onStationSeen("STN1");
+		service.registerReceivedQso(LOG_ID, 7L);
+
+		service.tick();
+		assertEquals(List.of(), sentRequests);
+
+		currentTimeMs += WinTestLogSyncService.INVENTORY_GRACE_PERIOD_MS;
+		service.tick();
+		receiveQsos(1L, 50L);
+		service.tick();
+
+		currentTimeMs += WinTestLogSyncService.REQUEST_TIMEOUT_MS;
+		service.tick();
+		currentTimeMs += WinTestLogSyncService.REQUEST_TIMEOUT_MS;
+		service.tick();
+
+		assertEquals(
+				List.of("STN1 " + LOG_ID + " 1-50", "STN1 " + LOG_ID + " 51-100"),
+				sentRequests);
+	}
+
+	@Test
+	void inventoryStopsTheBlindFallback() {
+		service.onStationSeen("STN1");
+		service.registerReceivedQso(LOG_ID, 7L);
+		currentTimeMs += WinTestLogSyncService.INVENTORY_GRACE_PERIOD_MS;
+
+		receiveIhave("IHAVE: \"STN1\" \"\" \"" + LOG_ID + "\" O 1 1 10");
+		service.tick();
+
+		assertEquals(List.of("STN1 " + LOG_ID + " 1-6"), sentRequests);
+	}
+
+	@Test
+	void ownPacketsDoNotStartASynchronization() {
+		service.onStationSeen("KST4Contest");
+
+		service.tick();
+
+		assertEquals(List.of(), sentRequests);
+		assertEquals(WinTestLogSyncService.SyncState.IDLE, service.getState());
+	}
+}

src/test/java/kst4contest/controller/WinTestNetworkAddressResolverTest.java

@@ -0,0 +1,85 @@
+package kst4contest.controller;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertFalse;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+
+import java.net.InetAddress;
+import java.net.UnknownHostException;
+
+import org.junit.jupiter.api.Test;
+
+class WinTestNetworkAddressResolverTest {
+
+	private static InetAddress address(String hostAddress) throws UnknownHostException {
+		return InetAddress.getByName(hostAddress);
+	}
+
+	@Test
+	void stationNetworkWinsOverConfiguredAddress() throws UnknownHostException {
+		WinTestNetworkAddressResolver resolver = new WinTestNetworkAddressResolver(
+				remoteAddress -> {
+					try {
+						return address("192.168.122.255");
+					} catch (UnknownHostException exception) {
+						return null;
+					}
+				});
+
+		resolver.rememberStationAddress(address("192.168.122.1"));
+
+		assertEquals(address("192.168.122.255"),
+				resolver.resolveBroadcastAddress("192.168.101.255"));
+	}
+
+	@Test
+	void configuredAddressIsUsedWhenNoLocalInterfaceServesTheStation()
+			throws UnknownHostException {
+		WinTestNetworkAddressResolver resolver =
+				new WinTestNetworkAddressResolver(remoteAddress -> null);
+
+		resolver.rememberStationAddress(address("10.9.8.7"));
+
+		assertEquals(address("192.168.101.255"),
+				resolver.resolveBroadcastAddress("192.168.101.255"));
+	}
+
+	@Test
+	void limitedBroadcastIsUsedWithoutStationAndWithoutSetting()
+			throws UnknownHostException {
+		WinTestNetworkAddressResolver resolver =
+				new WinTestNetworkAddressResolver(remoteAddress -> null);
+
+		assertEquals(address("255.255.255.255"), resolver.resolveBroadcastAddress("  "));
+		assertEquals(address("255.255.255.255"), resolver.resolveBroadcastAddress(null));
+	}
+
+	@Test
+	void loopbackAndWildcardSourcesAreIgnored() throws UnknownHostException {
+		WinTestNetworkAddressResolver resolver = new WinTestNetworkAddressResolver(
+				remoteAddress -> {
+					throw new IllegalStateException("must not be asked for " + remoteAddress);
+				});
+
+		resolver.rememberStationAddress(address("127.0.0.1"));
+		resolver.rememberStationAddress(address("0.0.0.0"));
+		resolver.rememberStationAddress(null);
+
+		assertEquals(address("192.168.101.255"),
+				resolver.resolveBroadcastAddress("192.168.101.255"));
+	}
+
+	@Test
+	void subnetComparisonHonoursThePrefixLength() throws UnknownHostException {
+		assertTrue(WinTestNetworkAddressResolver.isInSameSubnet(
+				address("192.168.122.1"), address("192.168.122.203"), 24));
+		assertFalse(WinTestNetworkAddressResolver.isInSameSubnet(
+				address("192.168.101.5"), address("192.168.122.1"), 24));
+		assertTrue(WinTestNetworkAddressResolver.isInSameSubnet(
+				address("172.19.0.1"), address("172.19.240.9"), 16));
+		assertFalse(WinTestNetworkAddressResolver.isInSameSubnet(
+				address("10.244.22.73"), address("10.244.23.1"), 24));
+		assertTrue(WinTestNetworkAddressResolver.isInSameSubnet(
+				address("10.244.22.73"), address("10.244.23.1"), 16));
+	}
+}

src/test/java/kst4contest/controller/WinTestPacketTest.java

@@ -0,0 +1,111 @@
+package kst4contest.controller;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertFalse;
+import static org.junit.jupiter.api.Assertions.assertNull;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+
+import java.nio.charset.StandardCharsets;
+import java.util.List;
+
+import org.junit.jupiter.api.Test;
+
+class WinTestPacketTest {
+
+	private static final String ADDQSO_MESSAGE =
+			"ADDQSO: \"STN1\" \"\" \"STN1\" 1762202297 1440000 0 12 0 0 0 2 2 "
+					+ "\"DM2RN\" \"599\" \"599001\" \"JO51UM\" \"\" \"\" 0 \"\" \"\" \"\" 44510";
+
+	/**
+	 * Builds a datagram exactly like Win-Test does: message text, checksum byte
+	 * replacing the placeholder, NUL terminator.
+	 */
+	private static byte[] toDatagram(String messageText) {
+		byte[] datagram = (messageText + "?\0").getBytes(StandardCharsets.US_ASCII);
+
+		int sum = 0;
+		for (int index = 0; index < datagram.length - 2; index++) {
+			sum += datagram[index] & 0xFF;
+		}
+
+		datagram[datagram.length - 2] = (byte) ((sum | 0x80) & 0xFF);
+		return datagram;
+	}
+
+	@Test
+	void checksumByteAndTerminatorAreRemovedFromMessageText() {
+		byte[] datagram = toDatagram(ADDQSO_MESSAGE);
+
+		WinTestPacket packet = WinTestPacket.fromDatagram(datagram, datagram.length);
+
+		assertEquals(ADDQSO_MESSAGE, packet.getMessageText());
+		assertTrue(packet.isChecksumPresent());
+		assertTrue(packet.isChecksumValid());
+	}
+
+	@Test
+	void trailingLogIdStaysReadableAfterFramingIsResolved() {
+		byte[] datagram = toDatagram(ADDQSO_MESSAGE);
+
+		WinTestPacket packet = WinTestPacket.fromDatagram(datagram, datagram.length);
+		List<String> packetFields = WinTestPacket.tokenize(packet.getMessageText());
+
+		assertEquals("STN1@44510",
+				ReadUDPByWintestThread.extractLogIdFromWinTestAddQso(packetFields));
+		assertEquals(2L,
+				ReadUDPByWintestThread.extractQsoNumberFromWinTestAddQso(packetFields));
+	}
+
+	@Test
+	void manipulatedChecksumIsDetected() {
+		byte[] datagram = toDatagram(ADDQSO_MESSAGE);
+		datagram[datagram.length - 2] = (byte) 0xFF;
+
+		WinTestPacket packet = WinTestPacket.fromDatagram(datagram, datagram.length);
+
+		assertTrue(packet.isChecksumPresent());
+		assertFalse(packet.isChecksumValid());
+	}
+
+	@Test
+	void sourceAndDestinationAreSeparatedFromPayload() {
+		byte[] datagram = toDatagram(
+				"IHAVE: \"STN1\" \"KST4Contest\" \"STN1@44510\" O 1 1 120");
+
+		WinTestPacket packet = WinTestPacket.fromDatagram(datagram, datagram.length);
+
+		assertEquals("IHAVE", packet.getMessageType());
+		assertEquals("STN1", packet.getSource());
+		assertEquals("KST4Contest", packet.getDestination());
+		assertEquals(List.of("STN1@44510", "O", "1", "1", "120"), packet.getDataTokens());
+		assertTrue(packet.isAddressedTo("KST4Contest"));
+		assertFalse(packet.isAddressedTo("STN2"));
+	}
+
+	@Test
+	void emptyQuotedFieldsKeepFieldPositions() {
+		List<String> packetFields = WinTestPacket.tokenize(ADDQSO_MESSAGE);
+
+		assertEquals("ADDQSO:", packetFields.get(0));
+		assertEquals("STN1", packetFields.get(1));
+		assertEquals("", packetFields.get(2));
+		assertEquals("12", packetFields.get(7));
+		assertEquals("DM2RN", packetFields.get(13));
+		assertEquals(24, packetFields.size());
+	}
+
+	@Test
+	void messageWithoutWinTestFramingIsRejected() {
+		assertNull(WinTestPacket.fromMessageText("no win-test message"));
+		assertNull(WinTestPacket.fromDatagram(new byte[] { 0 }, 1));
+		assertNull(WinTestPacket.fromDatagram(null, 0));
+	}
+
+	@Test
+	void broadcastPacketIsAcceptedForEveryStationName() {
+		WinTestPacket packet = WinTestPacket.fromMessageText(ADDQSO_MESSAGE);
+
+		assertTrue(packet.isAddressedTo("KST4Contest"));
+		assertFalse(packet.isChecksumPresent());
+	}
+}

udpReaderBackup.txt

@@ -2392,3 +2392,14 @@ SM6VTZ;Chris .135;JO58UJ;StringProperty [value: 432.135]; wkd true; wkd144 true;
 LA0BY;Stefan @ hilltop;JO59IX;StringProperty [value: 144.062]; wkd true; wkd144 true; wkd432false; wkd1240false; wkd2300false; wkd3400false; wkd5600false; wkd10Gfalse ; 2: 144/432 MHz
 LA0BY;null;JO49ML;StringProperty [value: null]; wkd true; wkd144 false; wkd432true; wkd1240false; wkd2300false; wkd3400false; wkd5600false; wkd10Gfalse ; null
 OV3T;null;JO46CM;StringProperty [value: null]; wkd true; wkd144 true; wkd432false; wkd1240false; wkd2300false; wkd3400false; wkd5600false; wkd10Gfalse ; null
+DK0TR;null;JO40QL;StringProperty [value: null]; wkd true; wkd144 true; wkd432false; wkd1240false; wkd2300false; wkd3400false; wkd5600false; wkd10Gfalse ; null
+DD0VF;null;JO61TB;StringProperty [value: null]; wkd true; wkd144 true; wkd432false; wkd1240false; wkd2300false; wkd3400false; wkd5600false; wkd10Gfalse ; null
+F5DYD;null;JN03KG;StringProperty [value: null]; wkd true; wkd144 true; wkd432false; wkd1240false; wkd2300false; wkd3400false; wkd5600false; wkd10Gfalse ; null
+F6DRO;null;JN03TJ;StringProperty [value: null]; wkd true; wkd144 true; wkd432false; wkd1240false; wkd2300false; wkd3400false; wkd5600false; wkd10Gfalse ; null
+F4VRB;null;IN98PT;StringProperty [value: null]; wkd true; wkd144 true; wkd432false; wkd1240false; wkd2300false; wkd3400false; wkd5600false; wkd10Gfalse ; null
+DK0TR;null;JO40QL;StringProperty [value: null]; wkd true; wkd144 true; wkd432false; wkd1240false; wkd2300false; wkd3400false; wkd5600false; wkd10Gfalse ; null
+DD0VF;null;JO61TB;StringProperty [value: null]; wkd true; wkd144 true; wkd432false; wkd1240false; wkd2300false; wkd3400false; wkd5600false; wkd10Gfalse ; null
+F5DYD;null;JN03KG;StringProperty [value: null]; wkd true; wkd144 true; wkd432false; wkd1240false; wkd2300false; wkd3400false; wkd5600false; wkd10Gfalse ; null
+F6DRO;null;JN03TJ;StringProperty [value: null]; wkd true; wkd144 true; wkd432false; wkd1240false; wkd2300false; wkd3400false; wkd5600false; wkd10Gfalse ; null
+F4VRB;null;IN98PT;StringProperty [value: null]; wkd true; wkd144 true; wkd432false; wkd1240false; wkd2300false; wkd3400false; wkd5600false; wkd10Gfalse ; null
+DK5KMA;null;JO50IK;StringProperty [value: null]; wkd true; wkd144 true; wkd432false; wkd1240false; wkd2300false; wkd3400false; wkd5600false; wkd10Gfalse ; null

website/src/features/log-sync.md

@@ -49,6 +49,8 @@ The general UDP listener processes packets from UCXLog, N1MM+, QARTest and DXLog
 
 Win-Test uses a separate listener for its native network protocol. KST4Contest resolves the Win-Test band ID, including 50 and 70 MHz, and stores the resulting Worked information in the same internal database.
 
+QSOs logged before KST4Contest was started are recovered from Win-Test as well. As soon as a Win-Test station is detected, the missing part of its log is requested over the native protocol, so stations already worked are marked as worked even when the client joins the contest late. The recovery needs no setting, keeps running to close gaps caused by lost packets, and covers every log in a multi-station network.
+
 STATUS packets can also update the local QRG when QRG synchronisation is enabled and valid packets actually arrive. Enabling the source alone does not supply a frequency. In multi-operator networks, a station-name filter prevents STATUS packets from another operating position from replacing the frequency of the intended radio.
 
 Win-Test can additionally receive skeds created in KST4Contest. The handover only takes place when a QRG matching the selected band can be determined. No fixed fallback frequency is inserted merely to make the packet technically valid.

website/src/news/2026-09-03-version-1-43.md

@@ -0,0 +1,29 @@
+---
+title: Version 1.43.1 released
+summary: Reliable log synchronisation, persistent layouts and better DX Cluster compatibility
+date: 2026-09-03
+---
+
+## Version 1.43.1
+
+Version 1.43 focuses on the parts of KST4Contest that have to keep working during a long contest: ON4KST connection monitoring, log synchronisation, Worked information and the data sent to external logging software.
+
+The first v1.43.0 packages already contained all functional changes described below, but some embedded version metadata still identified the build as version 1.42. v1.43.1 corrects this. If you already downloaded v1.43.0, use v1.43.1 instead.
+
+### What changed
+
+- **More reliable log synchronisation:** The Simplelogfile parser now closes the selected file after every pass, handles suffix variants by their base callsign and reports when a missing file has been created. UCXLog-compatible packets and Win-Test events share the same band normalisation, including the existing microwave bands.
+- **Correct Worked state after login:** Persisted Worked information is applied before the initial ON4KST user list becomes visible. Reconnects and both chat categories therefore start with the correct state.
+- **No false disconnect on a quiet server:** KST4Contest actively checks a quiet ON4KST session before treating it as dead. A period without new activity lines no longer causes an unnecessary reconnect.
+- **DX Cluster compatibility:** Local spots now use a fixed, DXSpider-compatible 75-character line format that is also accepted reliably by DXLog. Frequencies up to 24 GHz keep the required column positions.
+- **Layouts that stay where you put them:** Table column widths, window sizes and relevant dividers are saved automatically. Truncated table values expose their full text in a tooltip.
+- **Controllable map grouping:** **Group nearby stations** switches map clustering on or off without changing the current viewport or selected station.
+- **Smaller corrections:** Complete QRGs without a decimal separator are recognised across the supported bands, and private-message age highlighting no longer remains attached to reused table rows.
+
+The complete technical list is available in the [changelog](/manual/en/changelog/) and the [GitHub release notes](https://github.com/praktimarc/kst4contest/releases/tag/v1.43.1).
+
+### Getting it
+
+Packages for Windows, Linux and macOS are available on the [download page](/download/) and in the [GitHub release](https://github.com/praktimarc/kst4contest/releases/tag/v1.43.1). The AUR packages are updated through their normal release workflow.
+
+The German and English manuals have also been revised. The new contest-workflow chapter connects the individual functions into a practical operating sequence instead of describing them only in isolation. 73