Publishing the roster tags retries until the relay agrees

Same fault the iPhone had. The dirty flag was cleared before the attempt, so a
refusal was lost for good: the token was already stored, nothing asked again,
and that contact would never have seen a presence.

The set is compared against what the relay last accepted instead, and
republished until the two agree. The route replaces rather than merges, so
repeating a set that already landed changes nothing, which is what makes
retrying free.

Verified on the live relay: both accounts publish their own digest, and the
digests differ, because a token is per pair.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

app/src/main/kotlin/io/flamenet/messenger/app/Session.kt

@@ -2130,6 +2130,14 @@ class Session(
         }
     }
 
+    /**
+     * §8.9c. What the relay last accepted, so a refusal is retried and a set
+     * that already landed is not sent every pass. In memory on purpose: after
+     * a restart, publishing once more costs a request and settles any
+     * disagreement, where a persisted claim could be wrong and never tested.
+     */
+    private var publishedDigests: List<String> = emptyList()
+
     /**
      * §8.9c. Presence for the contacts this account holds a token for.
      *
@@ -2139,9 +2147,18 @@ class Session(
      */
     private fun presenceFromTokens(): Map<Long, String> {
         val held = conversations.presenceTokensHeld()
-        if (conversations.rosterTagsDirty) {
-            conversations.rosterTagsDirty = false
-            runCatching { api.publishRosterTags(conversations.rosterTagDigests()) }
+        // Compared against what the relay last ACCEPTED, not driven by a flag
+        // cleared before the attempt. The flag version lost a refusal for
+        // good: the token was already stored, so nothing asked again and that
+        // contact never saw a presence. The route replaces rather than merges,
+        // so repeating a set that already landed changes nothing.
+        val digests = conversations.rosterTagDigests()
+        if (digests.isNotEmpty() && digests != publishedDigests) {
+            runCatching { api.publishRosterTags(digests) }
+                .onSuccess {
+                    publishedDigests = digests
+                    conversations.rosterTagsDirty = false
+                }
         }
         if (held.isEmpty()) return emptyMap()
         val answers = runCatching { api.presenceByToken(held.keys.toList()) }