From a304cc34c423cee06db1a05d855b83a0d783d79e Mon Sep 17 00:00:00 2001
From: Niels Mokkenstorm <niels@mokkenstorm.dev>
Date: Tue, 11 Aug 2026 10:42:06 +0200
Subject: [PATCH] fix: dedupe the unpaged follow reads so they agree with the
 paged ones

---
 server/src/crate_server/follow_index.gleam | 16 ++++++++--------
 server/test/follow_index_test.gleam        |  5 ++++-
 2 files changed, 12 insertions(+), 9 deletions(-)

diff --git a/server/src/crate_server/follow_index.gleam b/server/src/crate_server/follow_index.gleam
index 636d4c0..14e1845 100644
--- a/server/src/crate_server/follow_index.gleam
+++ b/server/src/crate_server/follow_index.gleam
@@ -168,10 +168,10 @@ fn handle(state: State, msg: Msg) -> actor.Next(State, Msg) {
     Following(did, reply) -> {
       process.send(
         reply,
-        dict.values(state.follows)
-          |> list.filter(fn(f) { f.did == did })
-          |> list.map(fn(f) { f.subject })
-          |> list.sort(string.compare),
+        state.follows
+          |> matching_values(fn(follow) { follow.did == did }, fn(follow) {
+            follow.subject
+          }),
       )
       actor.continue(state)
     }
@@ -189,10 +189,10 @@ fn handle(state: State, msg: Msg) -> actor.Next(State, Msg) {
     Followers(did, reply) -> {
       process.send(
         reply,
-        dict.values(state.follows)
-          |> list.filter(fn(f) { f.subject == did })
-          |> list.map(fn(f) { f.did })
-          |> list.sort(string.compare),
+        state.follows
+          |> matching_values(fn(follow) { follow.subject == did }, fn(follow) {
+            follow.did
+          }),
       )
       actor.continue(state)
     }
diff --git a/server/test/follow_index_test.gleam b/server/test/follow_index_test.gleam
index bd72181..997e3d6 100644
--- a/server/test/follow_index_test.gleam
+++ b/server/test/follow_index_test.gleam
@@ -38,9 +38,12 @@ pub fn duplicate_records_are_preserved_until_their_uri_is_deleted_test() {
   let assert Ok(store) = follow_index.start()
   store.edges.upsert(follow("did:a", "did:b", "f1"))
   store.edges.upsert(follow("did:a", "did:b", "f2"))
-  assert store.edges.following("did:a") == ["did:b", "did:b"]
+  // One subject however many records point at it, matching the paged read.
+  assert store.edges.following("did:a") == ["did:b"]
   store.edges.delete("at://did:a/dev.mokkenstorm.crate.graph.follow/f1")
   assert store.edges.following("did:a") == ["did:b"]
+  store.edges.delete("at://did:a/dev.mokkenstorm.crate.graph.follow/f2")
+  assert store.edges.following("did:a") == []
 }
 
 pub fn following_is_empty_until_a_did_is_seen_test() {
-- 
2.51.2