diff --git a/Sources/RDReaderView/EPUBUI/ReaderController/RDEPUBPageMapReconciliationCoordinator.swift b/Sources/RDReaderView/EPUBUI/ReaderController/RDEPUBPageMapReconciliationCoordinator.swift
index 8ca00cc..03b85e8 100644
--- a/Sources/RDReaderView/EPUBUI/ReaderController/RDEPUBPageMapReconciliationCoordinator.swift
+++ b/Sources/RDReaderView/EPUBUI/ReaderController/RDEPUBPageMapReconciliationCoordinator.swift
@@ -52,6 +52,10 @@ final class RDEPUBPageMapReconciliationCoordinator {
                     let coverageRatio = Double(protectedIndices.intersection(candidateIndices).count) /
                                        Double(protectedIndices.count)
                     if coverageRatio < 0.8 {
+                        RDEPUBBackgroundTrace.log(
+                            "Reconciliation",
+                            "evaluateTakeover: keepCurrentWindow — jumpSession coverageRatio=\(String(format: "%.2f", coverageRatio)) protected=\(protectedIndices.count) candidateChapters=\(candidateIndices.count)"
+                        )
                         return .keepCurrentWindow
                     }
                 }
@@ -66,6 +70,10 @@ final class RDEPUBPageMapReconciliationCoordinator {
                     let hasPrev = candidateSegment.contains(spineIndex: currentSpineIndex - 1)
                     let hasNext = candidateSegment.contains(spineIndex: currentSpineIndex + 1)
                     if !hasPrev || !hasNext {
+                        RDEPUBBackgroundTrace.log(
+                            "Reconciliation",
+                            "evaluateTakeover: keepCurrentWindow — adjacentCoverage missing hasPrev=\(hasPrev) hasNext=\(hasNext) currentSpine=\(currentSpineIndex)"
+                        )
                         return .keepCurrentWindow
                     }
                 }
@@ -75,6 +83,10 @@ final class RDEPUBPageMapReconciliationCoordinator {
         if let candidateSegment {
             let currentRenderSignature = context.currentRenderSignature()
             if candidateSegment.renderSignature != currentRenderSignature {
+                RDEPUBBackgroundTrace.log(
+                    "Reconciliation",
+                    "evaluateTakeover: keepCurrentWindow — renderSignature mismatch segment=\(candidateSegment.renderSignature) current=\(currentRenderSignature)"
+                )
                 return .keepCurrentWindow
             }
         }
@@ -156,6 +168,10 @@ final class RDEPUBPageMapReconciliationCoordinator {
 
         if let currentSpineIndex {
             if !candidateIndices.contains(currentSpineIndex) {
+                RDEPUBBackgroundTrace.log(
+                    "Reconciliation",
+                    "evaluateFullPageMapTakeover: keepCurrentWindow — currentSpine=\(currentSpineIndex) not in candidate chapters=\(candidateIndices.count)"
+                )
                 return .keepCurrentWindow
             }
         }
@@ -165,6 +181,10 @@ final class RDEPUBPageMapReconciliationCoordinator {
             let hasNext = candidateIndices.contains(currentSpineIndex + 1) ||
                 currentSpineIndex == lastBuildableSpineIndex
             if !hasPrev || !hasNext {
+                RDEPUBBackgroundTrace.log(
+                    "Reconciliation",
+                    "evaluateFullPageMapTakeover: keepCurrentWindow — adjacentCoverage missing hasPrev=\(hasPrev) hasNext=\(hasNext) currentSpine=\(currentSpineIndex)"
+                )
                 return .keepCurrentWindow
             }
         }
diff --git a/Sources/RDReaderView/EPUBUI/ReaderController/RDEPUBPresentationRuntime.swift b/Sources/RDReaderView/EPUBUI/ReaderController/RDEPUBPresentationRuntime.swift
index 215fd22..668cb78 100644
--- a/Sources/RDReaderView/EPUBUI/ReaderController/RDEPUBPresentationRuntime.swift
+++ b/Sources/RDReaderView/EPUBUI/ReaderController/RDEPUBPresentationRuntime.swift
@@ -56,6 +56,10 @@ final class RDEPUBPresentationRuntime {
 
     func refreshBookPageMapInPlace(_ bookPageMap: RDEPUBBookPageMap) {
         navigationStateMachine.transition(to: .reconcilingFullMap)
+        RDEPUBBackgroundTrace.log(
+            "Reconciliation",
+            "refreshBookPageMapInPlace: enqueued reconcileFullMap chapters=\(bookPageMap.totalChapters) pages=\(bookPageMap.totalPages)"
+        )
         enqueuePendingPageMapUpdate(
             RDEPUBPendingPageMapUpdate(
                 pageMap: bookPageMap,
@@ -225,6 +229,10 @@ final class RDEPUBPresentationRuntime {
 
             switch decision {
             case .keepCurrentWindow:
+                RDEPUBBackgroundTrace.log(
+                    "Reconciliation",
+                    "commitPendingPageMapUpdate: keepCurrentWindow — removed pending update, totalPages=\(update.pageMap.totalPages)"
+                )
                 removePendingPageMapUpdate(at: index)
                 return false
 
@@ -238,7 +246,7 @@ final class RDEPUBPresentationRuntime {
                 return false
             }
 
-        case .extendPartial(let currentPageNumber, let currentLocation):
+        case .extendPartial(_, let currentLocation):
             removePendingPageMapUpdate(at: index)
             applyPageMapToLiveModel(update.pageMap, source: update.source)
             if let currentLocation,