fix: properly filter Nostr article highlights in sidebar

- Extract article coordinate from nostr: URLs using nip19.decode
- Filter highlights by eventReference matching the article coordinate
- Fix issue where unrelated highlights were showing in sidebar
- Apply same filtering logic to both useFilteredHighlights and filterHighlightsByUrl

src/hooks/useFilteredHighlights.ts

@@ -3,6 +3,7 @@ import { Highlight } from '../types/highlights'
 import { HighlightVisibility } from '../components/HighlightsPanel'
 import { normalizeUrl } from '../utils/urlHelpers'
 import { classifyHighlights } from '../utils/highlightClassification'
+import { nip19 } from 'nostr-tools'
 
 interface UseFilteredHighlightsParams {
   highlights: Highlight[]
@@ -24,8 +25,29 @@ export const useFilteredHighlights = ({
     
     let urlFiltered = highlights
     
-    // For Nostr articles, we already fetched highlights specifically for this article
-    if (!selectedUrl.startsWith('nostr:')) {
+    // Filter highlights based on URL type
+    if (selectedUrl.startsWith('nostr:')) {
+      // For Nostr articles, extract the article coordinate and filter by eventReference
+      try {
+        const decoded = nip19.decode(selectedUrl.replace('nostr:', ''))
+        if (decoded.type === 'naddr') {
+          const ptr = decoded.data as { kind: number; pubkey: string; identifier: string }
+          const articleCoordinate = `${ptr.kind}:${ptr.pubkey}:${ptr.identifier}`
+          
+          urlFiltered = highlights.filter(h => {
+            // Keep highlights that match this article coordinate
+            return h.eventReference === articleCoordinate
+          })
+        } else {
+          // Not a valid naddr, clear all highlights
+          urlFiltered = []
+        }
+      } catch {
+        // Invalid naddr, clear all highlights
+        urlFiltered = []
+      }
+    } else {
+      // For web URLs, filter by URL matching
       const normalizedSelected = normalizeUrl(selectedUrl)
       
       urlFiltered = highlights.filter(h => {

src/utils/urlHelpers.ts

@@ -1,4 +1,5 @@
 import { Highlight } from '../types/highlights'
+import { nip19 } from 'nostr-tools'
 
 export function normalizeUrl(url: string): string {
   try {
@@ -15,10 +16,26 @@ export function filterHighlightsByUrl(highlights: Highlight[], selectedUrl: stri
   }
   
   
-  // For Nostr articles, we already fetched highlights specifically for this article
-  // So we don't need to filter them - they're all relevant
+  // For Nostr articles, filter by article coordinate
   if (selectedUrl.startsWith('nostr:')) {
-    return highlights
+    try {
+      const decoded = nip19.decode(selectedUrl.replace('nostr:', ''))
+      if (decoded.type === 'naddr') {
+        const ptr = decoded.data as { kind: number; pubkey: string; identifier: string }
+        const articleCoordinate = `${ptr.kind}:${ptr.pubkey}:${ptr.identifier}`
+        
+        return highlights.filter(h => {
+          // Keep highlights that match this article coordinate
+          return h.eventReference === articleCoordinate
+        })
+      } else {
+        // Not a valid naddr, return empty array
+        return []
+      }
+    } catch {
+      // Invalid naddr, return empty array
+      return []
+    }
   }
   
   // For web URLs, filter by URL matching