From 019dde09e1ef80dbc48b928c6f05547547f9965d Mon Sep 17 00:00:00 2001
From: jpirnay <jens@pirnay.com>
Date: Wed, 8 Apr 2026 14:54:26 +0200
Subject: [PATCH] Deal with empty responses

---
 lib/KOReaderSync/KOReaderSyncClient.cpp | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/lib/KOReaderSync/KOReaderSyncClient.cpp b/lib/KOReaderSync/KOReaderSyncClient.cpp
index 7253416f..e0cd2eeb 100644
--- a/lib/KOReaderSync/KOReaderSyncClient.cpp
+++ b/lib/KOReaderSync/KOReaderSyncClient.cpp
@@ -441,6 +441,14 @@ KOReaderSyncClient::Error KOReaderSyncClient::getProgress(const std::string& doc
       return JSON_ERROR;
     }
 
+    // kosync convention: no stored progress for the document is signalled by
+    // HTTP 200 with an empty body ("{}"), not by 404. Detect that here so the
+    // caller doesn't apply a zeroed-out position as if it were real progress.
+    if (doc["document"].isNull() || doc["progress"].isNull()) {
+      LOG_DBG("KOSync", "Empty progress payload — treating as not found");
+      return NOT_FOUND;
+    }
+
     outProgress.document = documentHash;
     outProgress.progress = doc["progress"].as<std::string>();
     outProgress.percentage = doc["percentage"].as<float>();