feat: improve reading progress with validation and auto-mark

- Add autoMarkAsReadOnCompletion setting (opt-in, default: false)
- Implement auto-mark as read when reaching 95%+ completion
- Add validation for progress bounds (0-1) per NIP-39802 spec
- Align completion threshold to 95% to match filter behavior
- Skip invalid progress events with warning log

Improvements ensure consistency between completion detection and
filtering, while adding safety validation per the NIP spec.

src/components/ContentPanel.tsx

@@ -189,9 +189,10 @@ const ContentPanel: React.FC<ContentPanelProps> = ({
     syncEnabled: settings?.syncReadingPosition,
     onSave: handleSavePosition,
     onReadingComplete: () => {
-      // Optional: Auto-mark as read when reading is complete
-      if (activeAccount && !isMarkedAsRead) {
-        // Could trigger auto-mark as read here if desired
+      // Auto-mark as read when reading is complete (if enabled in settings)
+      if (activeAccount && !isMarkedAsRead && settings?.autoMarkAsReadOnCompletion) {
+        console.log('📖 [ContentPanel] Auto-marking as read on completion')
+        handleMarkAsRead()
       }
     }
   })

src/hooks/useReadingPosition.ts

@@ -4,7 +4,7 @@ interface UseReadingPositionOptions {
   enabled?: boolean
   onPositionChange?: (position: number) => void
   onReadingComplete?: () => void
-  readingCompleteThreshold?: number // Default 0.9 (90%)
+  readingCompleteThreshold?: number // Default 0.95 (95%) - matches filter threshold
   syncEnabled?: boolean // Whether to sync positions to Nostr
   onSave?: (position: number) => void // Callback for saving position
   autoSaveInterval?: number // Auto-save interval in ms (default 5000)
@@ -14,7 +14,7 @@ export const useReadingPosition = ({
   enabled = true,
   onPositionChange,
   onReadingComplete,
-  readingCompleteThreshold = 0.9,
+  readingCompleteThreshold = 0.95, // Match filter threshold for consistency
   syncEnabled = false,
   onSave,
   autoSaveInterval = 5000

src/services/readingDataProcessor.ts

@@ -36,6 +36,13 @@ export function processReadingProgress(
     try {
       const content = JSON.parse(event.content)
       const position = content.progress || 0
+      
+      // Validate progress is between 0 and 1 (NIP-39802 requirement)
+      if (position < 0 || position > 1) {
+        console.warn('Invalid progress value (must be 0-1):', position, 'event:', event.id.slice(0, 8))
+        continue
+      }
+      
       // Use event.created_at as authoritative timestamp (NIP-39802 spec)
       const timestamp = event.created_at
 

src/services/settingsService.ts

@@ -60,6 +60,7 @@ export interface UserSettings {
   paragraphAlignment?: 'left' | 'justify' // default: justify
   // Reading position sync
   syncReadingPosition?: boolean // default: false (opt-in)
+  autoMarkAsReadOnCompletion?: boolean // default: false (opt-in)
 }
 
 export async function loadSettings(