diff --git a/web/src/lib/tinode/topics.ts b/web/src/lib/tinode/topics.ts
index 3e491212..67ca97e9 100644
--- a/web/src/lib/tinode/topics.ts
+++ b/web/src/lib/tinode/topics.ts
@@ -71,6 +71,24 @@ export function getP2PPeerUserId(topic: Topic, myUserId: string | null | undefin
 }
 
 const confirmedReadSeq = new Map<string, number>();
+// Tinode reserves this sequence and higher values for optimistic local messages.
+const LOCAL_SEQID = 0xfffffff;
+
+export function getConfirmedRead(topicName: string): number {
+  const seq = confirmedReadSeq.get(topicName) || 0;
+  return seq > 0 && seq < LOCAL_SEQID ? seq : 0;
+}
+
+/** Repair an SDK contact polluted by a local sequence before it reaches the list or sync snapshot. */
+export function repairContactReadState(contact: Pick<Contact, 'seq' | 'read' | 'recv' | 'unread'>): void {
+  const seq = contact.seq || 0;
+  const read = contact.read || 0;
+  const recv = contact.recv || 0;
+  if (read < LOCAL_SEQID && recv < LOCAL_SEQID && read <= seq && recv <= seq && (contact.unread || 0) >= 0) return;
+  contact.read = Math.min(Math.max(0, read), seq);
+  contact.recv = Math.min(Math.max(contact.read, recv), seq);
+  contact.unread = Math.max(0, seq - contact.read);
+}
 
 /**
  * This app's OWN independent record of "the user has genuinely seen up to `seq` in this topic" --
@@ -83,7 +101,8 @@ const confirmedReadSeq = new Map<string, number>();
  * actually visible.
  */
 export function markConfirmedRead(topicName: string, seq: number) {
-  const prev = confirmedReadSeq.get(topicName) || 0;
+  if (!Number.isInteger(seq) || seq <= 0 || seq >= LOCAL_SEQID) return;
+  const prev = getConfirmedRead(topicName);
   if (seq > prev) confirmedReadSeq.set(topicName, seq);
 }
 
@@ -438,7 +457,8 @@ export function subscribeMeTopic(): Promise<unknown> {
     // Cast for the same reason getChatListSnapshot does -- read/unread/seq are real fields the SDK
     // sets directly on the Topic instance at runtime, just not declared on this hand-maintained .d.ts.
     const topic = getTinode().getTopic(topicName) as unknown as Contact;
-    const correctRead = confirmedReadSeq.get(topicName) || 0;
+    repairContactReadState(topic);
+    const correctRead = getConfirmedRead(topicName);
     if ((topic.read || 0) > correctRead) {
       topic.read = correctRead;
       topic.unread = Math.max(0, (topic.seq || 0) - correctRead);
@@ -620,7 +640,10 @@ function isChatListTopicName(name: string): boolean {
  * subscribe (`subscribeMeTopic`'s `withLaterSub()`) and any direct `openConversation()` both populate.
  */
 export function getChatListSnapshot(): Contact[] {
-  if (chatListSnapshot) return chatListSnapshot;
+  if (chatListSnapshot) {
+    chatListSnapshot.forEach(repairContactReadState);
+    return chatListSnapshot;
+  }
   const byTopic = new Map<string, Contact>();
   getTinode().mapTopics((topic) => {
     if (!topic.name || !isChatListTopicName(topic.name) || goneTopicNames.has(topic.name)) return;
@@ -633,6 +656,7 @@ export function getChatListSnapshot(): Contact[] {
     // (not a clone) so prototype methods like `latestMessage()` survive.
     const contact = topic as unknown as Contact;
     contact.topic = topic.name;
+    repairContactReadState(contact);
     byTopic.set(topic.name, contact);
   });
   const rows = [...byTopic.values()];
@@ -780,7 +804,7 @@ function reconcileMeSubs() {
         // `read` to what THIS client already knows it has confirmed seeing, regardless of what the
         // fetch says -- a floor, never pushes `read` past the server's own value when the server is
         // genuinely ahead of this record (e.g. read from a different, already-synced device).
-        const confirmed = confirmedReadSeq.get(c.topic) || 0;
+        const confirmed = getConfirmedRead(c.topic);
         if (confirmed > (c.read || 0)) {
           c.read = confirmed;
           if ((c.recv || 0) < confirmed) c.recv = confirmed;
diff --git a/web/tests/unread-cursor.test.mjs b/web/tests/unread-cursor.test.mjs
new file mode 100644
index 00000000..26ac3094
--- /dev/null
+++ b/web/tests/unread-cursor.test.mjs
@@ -0,0 +1,35 @@
+import assert from 'node:assert/strict';
+import test from 'node:test';
+import { fileURLToPath } from 'node:url';
+
+import { createJiti } from 'jiti';
+
+globalThis.__APP_VERSION__ = 'test';
+globalThis.window = { addEventListener() {}, removeEventListener() {} };
+
+const jiti = createJiti(import.meta.url, { alias: { '@': fileURLToPath(new URL('../src', import.meta.url)) } });
+const { getConfirmedRead, markConfirmedRead, repairContactReadState } = await jiti.import('../src/lib/tinode/topics.ts');
+const LOCAL_SEQID = 0xfffffff;
+
+test('optimistic local sequence never advances the confirmed read cursor', () => {
+  markConfirmedRead('unread-cursor-test', 260);
+  markConfirmedRead('unread-cursor-test', LOCAL_SEQID);
+  assert.equal(getConfirmedRead('unread-cursor-test'), 260);
+  markConfirmedRead('unread-cursor-test', 267);
+  assert.equal(getConfirmedRead('unread-cursor-test'), 267);
+});
+
+test('repairs existing negative unread counts caused by local sequence IDs', () => {
+  for (const seq of [260, 267]) {
+    const contact = { seq, read: LOCAL_SEQID, recv: LOCAL_SEQID, unread: seq - LOCAL_SEQID };
+    assert.equal(contact.unread, seq === 260 ? -268435195 : -268435188);
+    repairContactReadState(contact);
+    assert.deepEqual(contact, { seq, read: seq, recv: seq, unread: 0 });
+  }
+});
+
+test('keeps valid read and unread state unchanged', () => {
+  const contact = { seq: 267, read: 260, recv: 265, unread: 7 };
+  repairContactReadState(contact);
+  assert.deepEqual(contact, { seq: 267, read: 260, recv: 265, unread: 7 });
+});