From 7cd27b77a530f4daa291165d817d3961af8d70f6 Mon Sep 17 00:00:00 2001
From: Guillermo Serrahima <dev@vylion.com>
Date: Sat, 21 Mar 2026 16:20:13 +0100
Subject: Fixing thread deduplication

---
 backend/notes/note.go | 17 ++++++++---------
 1 file changed, 8 insertions(+), 9 deletions(-)

diff --git a/backend/notes/note.go b/backend/notes/note.go
index c427a8f..8a73b70 100644
--- a/backend/notes/note.go
+++ b/backend/notes/note.go
@@ -35,23 +35,22 @@ func MissingNote(uri string) *Note {
 	}
 }
 
-func isChainContained(smallChain, bigChain []Note) bool {
-	if len(smallChain) > len(bigChain) {
+func isChainContained(smallChainPost, bigChainPost Note) bool {
+	if len(smallChainPost.Parents) > len(bigChainPost.Parents) {
 		return false
 	}
 
-	// check if smallChain is a suffix of bigChain
-	offset := len(bigChain) - len(smallChain)
-	for i, note := range smallChain {
-		if bigChain[offset+i].URI != note.URI {
+	// check if parents of smallChainPost are included in bigChainPost
+	offset := len(bigChainPost.Parents) - len(smallChainPost.Parents)
+	for i, note := range smallChainPost.Parents {
+		if bigChainPost.Parents[offset+i].URI != note.URI {
 			return false
 		}
 	}
-	return true
+	return smallChainPost.URI == bigChainPost.Parents[offset-1].URI
 }
 
 func DeduplicateThreads(posts []Note) []Note {
-	// sort by parent chain length (longest first)
 	sort.Slice(posts, func(i, j int) bool {
 		return len(posts[i].Parents) > len(posts[j].Parents)
 	})
@@ -61,7 +60,7 @@ func DeduplicateThreads(posts []Note) []Note {
 		isRedundant := false
 		for _, kept := range filtered {
 			// check if this post's chain is contained in any kept post
-			if isChainContained(post.Parents, kept.Parents) && post.URI == kept.URI {
+			if isChainContained(post, kept) {
 				isRedundant = true
 				break
 			}
-- 
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