diff --git a/Client/tauri-client/src/lib/dispatcher.ts b/Client/tauri-client/src/lib/dispatcher.ts
index b39d9bd0..c4558451 100644
--- a/Client/tauri-client/src/lib/dispatcher.ts
+++ b/Client/tauri-client/src/lib/dispatcher.ts
@@ -31,6 +31,7 @@ import {
   invalidateLoadedMessageWindows,
   setChannelLoading,
   setChannelLoadError,
+  isWindowDetached,
 } from "@stores/messages.store";
 import {
   setMembers,
@@ -65,7 +66,12 @@ import {
   updateDmParticipant,
 } from "@stores/dm.store";
 import type { DmChannel } from "@stores/dm.store";
-import { setBlockedByMe, setUserBlockedByThem, clearBlockedByThem } from "@stores/blocks.store";
+import {
+  blocksStore,
+  setBlockedByMe,
+  setUserBlockedByThem,
+  clearBlockedByThem,
+} from "@stores/blocks.store";
 import { setCustomEmoji } from "@stores/emoji.store";
 import type { DmChannelPayload } from "./types";
 import { isTextLikeChannel } from "./types";
@@ -267,6 +273,16 @@ export function wireDispatcher(
 
   unsubs.push(
     ws.on(S.READY, (payload) => {
+      // OC-0201: snapshot the current voice channel's peer roster BEFORE the
+      // wholesale replace below, so the reconciliation branch further down
+      // can tell who left while the socket was down. Must run before
+      // setVoiceStates() overwrites voiceUsers with the fresh payload.
+      const prevVoiceChannelId = voiceStore.getState().currentChannelId;
+      const prevVoicePeerIds =
+        prevVoiceChannelId !== null
+          ? new Set(voiceStore.getState().voiceUsers.get(prevVoiceChannelId)?.keys() ?? [])
+          : new Set<number>();
+
       setChannels(payload.channels);
       setRoles(payload.roles ?? []);
       setMembers(payload.members);
@@ -303,6 +319,31 @@ export function wireDispatcher(
           selfVoiceState.server_muted === true,
           selfVoiceState.server_deafened === true,
         );
+
+        // OC-0201: same gap, for E2EE. A full resync never replays the
+        // voice_leave for anyone who departed our voice channel during the
+        // outage — handleParticipantLeft (the only path that prunes a
+        // departed peer's key, rotates for membership forward secrecy, and
+        // re-runs the lowest-uid key-holder election) is otherwise only ever
+        // driven by a live voice_leave frame. Without this, a departed peer
+        // keeps a working room key indefinitely, and a client the server
+        // just elected key holder on reconnect (Server/ws hub.go
+        // registerNow -> updateKeyHolder) never self-elects. Only reconcile
+        // when the resync's self voice state is for the SAME channel the
+        // snapshot above was taken from — a channel change is out of scope
+        // here and comparing rosters across two different channels would
+        // misfire.
+        if (prevVoiceChannelId === selfVoiceState.channel_id) {
+          const currentVoicePeerIds = new Set(
+            payload.voice_states
+              .filter((vs) => vs.channel_id === selfVoiceState.channel_id)
+              .map((vs) => vs.user_id),
+          );
+          for (const uid of prevVoicePeerIds) {
+            if (uid === currentUserId || currentVoicePeerIds.has(uid)) continue;
+            void livekitSession().then(({ handleParticipantLeft }) => handleParticipantLeft(uid));
+          }
+        }
       }
 
       // F3: publish our long-term identity public key so peers can pin+verify
@@ -463,9 +504,17 @@ export function wireDispatcher(
       // clear it and re-fetch our own outgoing blocks authoritatively.
       clearBlockedByThem();
       if (api !== undefined) {
+        // OC-0218: snapshot the revision blocksStore was at right before
+        // issuing this fetch. If the user blocks/unblocks someone (via
+        // SidebarMemberSection's onToggleBlock -> setUserBlockedByMe) while
+        // this GET is in flight, that per-user delta bumps the revision;
+        // setBlockedByMe then sees the mismatch and skips applying this
+        // reply instead of clobbering the fresher local truth with a stale
+        // full-set snapshot.
+        const blockedByMeRevAtFetch = blocksStore.getState().blockedByMeRev ?? 0;
         api
           .listBlocks()
-          .then((r) => setBlockedByMe(r.blocked_user_ids))
+          .then((r) => setBlockedByMe(r.blocked_user_ids, blockedByMeRevAtFetch))
           .catch((err) => log.warn("Failed to load block list", { error: String(err) }));
       }
 
@@ -566,30 +615,46 @@ export function wireDispatcher(
       const currentUserId = authStore.getState().user?.id ?? null;
       const isOwnMessage = currentUserId !== null && payload.user.id === currentUserId;
 
-      // Increment channel-level unread for non-active, non-own-message channels.
-      // Replayed frames increment unread counts like live ones — the burst
-      // is exactly the messages missed while away (a full-ready resume sends
-      // no burst at all; ready's unread_count values are authoritative
-      // there). DM channel IDs are not in channelsStore (they use dmStore),
-      // so incrementUnread is a no-op for DMs, but the own-message guard is
-      // applied here for defence-in-depth.
+      // Increment channel-level unread for non-active, non-own-message
+      // channels — OR for the active channel when its loaded window is
+      // detached from the live tail (OC-0204). "Active" normally means "the
+      // user is watching the live tail", which is why it is otherwise
+      // excluded here, but a jump to an old permalink/reply/search hit can
+      // leave the active channel showing a detached around-window
+      // (messages.store's detachedChannels) — addMessage already refuses to
+      // append a live broadcast onto that window, so without this a message
+      // (an @mention included) that arrives while the user reads
+      // back-history leaves no row AND no badge, with nothing to tell them
+      // it ever arrived. Replayed frames increment unread counts like live
+      // ones — the burst is exactly the messages missed while away (a
+      // full-ready resume sends no burst at all; ready's unread_count values
+      // are authoritative there). DM channel IDs are not in channelsStore
+      // (they use dmStore), so incrementUnread is a no-op for DMs, but the
+      // own-message guard is applied here for defence-in-depth.
       const isMention = highlightsCurrentUser(payload.content, {
         mentions: payload.mentions,
         mentionsEveryone: payload.mentions_everyone,
       });
+      const isDetached = isWindowDetached(payload.channel_id);
 
-      if (payload.channel_id !== activeId && !isOwnMessage) {
-        incrementUnread(payload.channel_id);
+      if ((payload.channel_id !== activeId || isDetached) && !isOwnMessage) {
+        // incrementUnread/incrementMention skip the active channel by
+        // default — evenIfActive (isDetached here) is a no-op for a
+        // genuinely non-active channel, since their internal guard only
+        // fires when channelId IS the active one.
+        incrementUnread(payload.channel_id, isDetached);
         // A mention is an unread too — the mention badge just outranks it.
         if (isMention) {
-          incrementMention(payload.channel_id);
+          incrementMention(payload.channel_id, isDetached);
         }
       }
 
       // Update DM store last message if this message belongs to a DM channel.
-      // Skip unread increment for own messages and the currently focused DM.
+      // Skip unread increment for own messages and the currently focused DM
+      // — unless that DM's window is detached from the live tail (OC-0204),
+      // the same exception the channel-level increment above makes.
       if (isDm) {
-        const isDmActive = payload.channel_id === activeId;
+        const isDmActive = payload.channel_id === activeId && !isDetached;
         if (isOwnMessage || isDmActive) {
           // Update last message preview but don't increment unread count.
           updateDmLastMessagePreview(
@@ -1111,10 +1176,22 @@ export function wireDispatcher(
       // that voice_leave's channel no longer matches the already-updated
       // currentChannelId, so it must not tear down the NEW channel's
       // optimistic state either), so voiceStatus is still "joining" when
-      // this error lands and the guard clears it here instead. An
-      // already-established session is never in "joining", so this never
-      // touches a live voice call.
+      // this error lands and the guard clears it here instead. A plain
+      // store rollback is safe for an already-established session (never
+      // "joining") and for a first-time join refusal (no prior session to
+      // tear down) — but a channel *switch* refused at precheck (RATE_LIMITED,
+      // FORBIDDEN, NOT_FOUND, archived-channel BAD_REQUEST) never reaches
+      // voiceJoinLeaveCurrent server-side, so no voice_leave is broadcast and
+      // the OLD channel's LiveKit room is still connected (mic still
+      // published) while the store already points at the NEW channel
+      // (OC-0193). isVoiceConnected() distinguishes that live-session case
+      // from the first-time-join refusal; tearing it down here also sends
+      // voice_leave so the server/SFU state for the OLD channel matches the
+      // now-cleared store.
       if (voiceStore.getState().voiceStatus === "joining") {
+        void livekitSession().then(({ isVoiceConnected, leaveVoice }) => {
+          if (isVoiceConnected()) leaveVoice(true);
+        });
         leaveVoiceChannel();
       }
       // Voice capacity refusals. The server owns the limits (voice_max_users /
diff --git a/Client/tauri-client/src/lib/notifications.ts b/Client/tauri-client/src/lib/notifications.ts
index fdb082c8..7fdd001d 100644
--- a/Client/tauri-client/src/lib/notifications.ts
+++ b/Client/tauri-client/src/lib/notifications.ts
@@ -9,6 +9,7 @@ import { loadUserStatus } from "./userStatus";
 import { authStore } from "@stores/auth.store";
 import { channelsStore } from "@stores/channels.store";
 import { dmStore, dmDisplayName } from "@stores/dm.store";
+import { isWindowDetached } from "@stores/messages.store";
 import type { ChatMessagePayload } from "./types";
 import { mentionsCurrentUser } from "./mentions";
 import { createLogger } from "./logger";
@@ -53,9 +54,22 @@ export function notifyIncomingMessage(payload: ChatMessagePayload): void {
   // Don't notify for own messages
   if (currentUser !== null && payload.user.id === currentUser.id) return;
 
-  // Don't notify if the window is focused AND the message is in the active channel
+  // Don't notify if the window is focused AND the message is in the active
+  // channel — UNLESS that channel is showing a detached around-window
+  // (OC-0204). "Active" only means this is the channel on screen; a jump to
+  // an old permalink/reply/search hit can leave it detached from the live
+  // tail (messages.store's detachedChannels), in which case the user is
+  // reading back-history and cannot see the new message at all — addMessage
+  // silently refuses to append it. Without this check that combination
+  // suppresses the one thing that would have told the user anything arrived.
   const activeChannelId = channelsStore.getState().activeChannelId;
-  if (isWindowFocused() && payload.channel_id === activeChannelId) return;
+  if (
+    isWindowFocused() &&
+    payload.channel_id === activeChannelId &&
+    !isWindowDetached(payload.channel_id)
+  ) {
+    return;
+  }
 
   const mentionInfo = {
     mentions: payload.mentions,
diff --git a/Client/tauri-client/src/pages/main-page/ChannelController.ts b/Client/tauri-client/src/pages/main-page/ChannelController.ts
index 28284b6d..4413d999 100644
--- a/Client/tauri-client/src/pages/main-page/ChannelController.ts
+++ b/Client/tauri-client/src/pages/main-page/ChannelController.ts
@@ -223,6 +223,13 @@ export function createChannelController(opts: ChannelControllerOptions): Channel
       // onJumpToPresent — reattach clears "loaded" so the tail is refetched.
       if (isWindowDetached(channelId)) {
         reattachToPresent(channelId);
+        // OC-0204: while detached, this (already-active) channel could have
+        // picked up an unread/mention badge for messages that arrived below
+        // the gap (dispatcher.ts's evenIfActive path) — nothing else clears
+        // it, since incrementUnread's usual "active channel" skip is exactly
+        // what a detached window opts out of. Jumping to present is reading
+        // it, so mark it read the same way leaving a channel does.
+        markChannelRead(channelId);
         if (channelAbort !== null) {
           void msgCtrl.loadMessages(channelId, channelAbort.signal);
         }
@@ -288,6 +295,11 @@ export function createChannelController(opts: ChannelControllerOptions): Channel
         // Dropping the detached flag also clears "loaded", so loadMessages
         // refetches the live tail instead of short-circuiting.
         reattachToPresent(channelId);
+        // OC-0204: see performSend's identical call above — a detached
+        // active channel's badge (from dispatcher.ts's evenIfActive path)
+        // must be cleared here too, or it lingers after the user has jumped
+        // back to present and is looking straight at the live tail.
+        markChannelRead(channelId);
         if (channelAbort !== null) {
           void msgCtrl.loadMessages(channelId, channelAbort.signal);
         }
diff --git a/Client/tauri-client/src/stores/blocks.store.ts b/Client/tauri-client/src/stores/blocks.store.ts
index fec91125..ac12a302 100644
--- a/Client/tauri-client/src/stores/blocks.store.ts
+++ b/Client/tauri-client/src/stores/blocks.store.ts
@@ -21,18 +21,43 @@ export const BLOCKED_BY_THEM_REASON = "You can't message this user right now.";
 export interface BlocksState {
   readonly blockedByMe: ReadonlySet<number>;
   readonly blockedByThem: ReadonlySet<number>;
+  /**
+   * Bumped by every accepted setUserBlockedByMe delta (OC-0218). Optional —
+   * absent/undefined reads as revision 0 — so state literals that predate
+   * this field (tests, a full setState replace) do not need updating.
+   *
+   * Lets a ready-time GET /blocks snapshot the revision it observed just
+   * before issuing the request and pass it back to setBlockedByMe: if a
+   * setUserBlockedByMe delta landed (bumping the revision) while that fetch
+   * was in flight, the fetch's reply is answering a question that is no
+   * longer current and must not clobber the fresher local truth.
+   */
+  readonly blockedByMeRev?: number;
 }
 
 const INITIAL: BlocksState = {
   blockedByMe: new Set(),
   blockedByThem: new Set(),
+  blockedByMeRev: 0,
 };
 
 export const blocksStore = createStore<BlocksState>(INITIAL);
 
-/** Replace the blocked-by-me set (from GET /blocks). */
-export function setBlockedByMe(userIds: readonly number[]): void {
-  blocksStore.setState((prev) => ({ ...prev, blockedByMe: new Set(userIds) }));
+/**
+ * Replace the blocked-by-me set (from GET /blocks).
+ *
+ * `rev`, when given, must match the store's current blockedByMeRev — the
+ * revision the caller observed right before starting the fetch this reply
+ * answers (OC-0218). A mismatch means a fresher setUserBlockedByMe delta
+ * landed after the fetch was issued, so this reply is stale and is skipped
+ * rather than reverting that delta. Omit `rev` to always apply (existing
+ * direct callers, tests).
+ */
+export function setBlockedByMe(userIds: readonly number[], rev?: number): void {
+  blocksStore.setState((prev) => {
+    if (rev !== undefined && rev !== (prev.blockedByMeRev ?? 0)) return prev;
+    return { ...prev, blockedByMe: new Set(userIds) };
+  });
 }
 
 /** Mark (or unmark) a user as blocked by the local user (after PUT/DELETE /blocks). */
@@ -42,7 +67,7 @@ export function setUserBlockedByMe(userId: number, blocked: boolean): void {
     const next = new Set(prev.blockedByMe);
     if (blocked) next.add(userId);
     else next.delete(userId);
-    return { ...prev, blockedByMe: next };
+    return { ...prev, blockedByMe: next, blockedByMeRev: (prev.blockedByMeRev ?? 0) + 1 };
   });
 }
 
diff --git a/Client/tauri-client/src/stores/channels.store.ts b/Client/tauri-client/src/stores/channels.store.ts
index f8b9b536..d9001da7 100644
--- a/Client/tauri-client/src/stores/channels.store.ts
+++ b/Client/tauri-client/src/stores/channels.store.ts
@@ -333,10 +333,19 @@ export function getChannelsByCategory(): Map<string | null, Channel[]> {
   });
 }
 
-/** Increment unread count for a channel, unless it is the active channel. */
-export function incrementUnread(channelId: number): void {
+/**
+ * Increment unread count for a channel, unless it is the active channel.
+ *
+ * `evenIfActive` (OC-0204) opts out of that skip: "active" normally means
+ * "the user is watching the live tail" — the reason a badge would be
+ * redundant there — but the active channel's loaded window can be detached
+ * from the live tail (a jump to an old permalink/reply/search hit), in which
+ * case the message is genuinely unseen and must still count. Callers own
+ * deciding when that applies; this still always skips an unknown channel id.
+ */
+export function incrementUnread(channelId: number, evenIfActive = false): void {
   channelsStore.setState((prev) => {
-    if (prev.activeChannelId === channelId) {
+    if (prev.activeChannelId === channelId && !evenIfActive) {
       return prev;
     }
     const existing = prev.channels.get(channelId);
@@ -357,10 +366,12 @@ export function incrementUnread(channelId: number): void {
  * Increment the mention count for a channel, unless it is the active channel.
  * Callers also call incrementUnread — a mention is always an unread too, and
  * the two counters are kept independent so the badge can outrank.
+ *
+ * `evenIfActive` mirrors incrementUnread's escape hatch — see its doc for why.
  */
-export function incrementMention(channelId: number): void {
+export function incrementMention(channelId: number, evenIfActive = false): void {
   channelsStore.setState((prev) => {
-    if (prev.activeChannelId === channelId) {
+    if (prev.activeChannelId === channelId && !evenIfActive) {
       return prev;
     }
     const existing = prev.channels.get(channelId);
diff --git a/Client/tauri-client/tests/unit/blocks-store.test.ts b/Client/tauri-client/tests/unit/blocks-store.test.ts
index 4fd32e66..f1ee9977 100644
--- a/Client/tauri-client/tests/unit/blocks-store.test.ts
+++ b/Client/tauri-client/tests/unit/blocks-store.test.ts
@@ -2,6 +2,7 @@ import { describe, it, expect, beforeEach } from "vitest";
 import {
   blocksStore,
   setBlockedByMe,
+  setUserBlockedByMe,
   setUserBlockedByThem,
   clearBlockedByThem,
   dmComposerBlockReason,
@@ -80,4 +81,46 @@ describe("blocksStore", () => {
       expect(blocksStore.getState()).toBe(before);
     });
   });
+
+  // OC-0218: a ready-time GET /blocks and a user-initiated block/unblock can
+  // race. The GET is issued before the user's own action but its reply can
+  // land after — a stale full-set reply must not clobber a fresher per-user
+  // delta.
+  describe("setBlockedByMe staleness guard (OC-0218)", () => {
+    it("applies when no revision is given (direct/legacy caller)", () => {
+      setBlockedByMe([5]);
+      expect(dmComposerBlockReason(blocksStore.getState(), 5)).toBe(BLOCKED_BY_ME_REASON);
+    });
+
+    it("a reply carrying the revision observed before a fresher local delta must not re-add it", () => {
+      // Local user 42 starts blocked (seeded, as if from a previous ready).
+      setBlockedByMe([42]);
+      // A reconnect fires a fresh GET /blocks — the caller snapshots the
+      // revision it observed right before issuing the request. Real callers
+      // (dispatcher.ts) default the optional field to 0, exactly like
+      // setBlockedByMe's own internal comparison does.
+      const revBeforeFetch = blocksStore.getState().blockedByMeRev ?? 0;
+
+      // While that GET is in flight, the user clicks "Unblock" — this is the
+      // fresher, authoritative local truth.
+      setUserBlockedByMe(42, false);
+      expect(dmComposerBlockReason(blocksStore.getState(), 42)).toBeNull();
+
+      // The GET's reply lands late, still carrying the stale pre-unblock
+      // snapshot and the revision observed before the unblock. It must be
+      // ignored, not re-add 42.
+      setBlockedByMe([42], revBeforeFetch);
+
+      expect(dmComposerBlockReason(blocksStore.getState(), 42)).toBeNull();
+    });
+
+    it("a reply carrying the current revision still applies", () => {
+      setBlockedByMe([1]);
+      const rev = blocksStore.getState().blockedByMeRev;
+      // No local delta happened since — the snapshot is still current.
+      setBlockedByMe([1, 2], rev);
+      expect(dmComposerBlockReason(blocksStore.getState(), 1)).toBe(BLOCKED_BY_ME_REASON);
+      expect(dmComposerBlockReason(blocksStore.getState(), 2)).toBe(BLOCKED_BY_ME_REASON);
+    });
+  });
 });
diff --git a/Client/tauri-client/tests/unit/channel-controller.test.ts b/Client/tauri-client/tests/unit/channel-controller.test.ts
index 257634f7..d6734b6b 100644
--- a/Client/tauri-client/tests/unit/channel-controller.test.ts
+++ b/Client/tauri-client/tests/unit/channel-controller.test.ts
@@ -518,6 +518,7 @@ describe("createChannelController", () => {
       // After a jump into history the composer stays enabled; sending must
       // land the optimistic row in the live tail, not mid-history.
       mockIsWindowDetached.mockReturnValueOnce(true);
+      mockMarkChannelRead.mockClear();
       const opts = makeOpts();
       const ctrl = createChannelController(opts);
       ctrl.mountChannel(42, "general");
@@ -530,6 +531,10 @@ describe("createChannelController", () => {
       expect(opts.msgCtrl.loadMessages).toHaveBeenCalledWith(42, expect.any(AbortSignal));
       // The send itself still goes out.
       expect(opts.ws.send).toHaveBeenCalledWith(expect.objectContaining({ type: "chat_send" }));
+      // OC-0204: a detached-but-active channel can carry an unread/mention
+      // badge dispatcher.ts left behind for messages missed below the gap —
+      // jumping to present (which sending here implies) must clear it.
+      expect(mockMarkChannelRead).toHaveBeenCalledWith(42);
     });
 
     it("onSend while disconnected records a failed optimistic row (no silent drop)", () => {
@@ -582,6 +587,7 @@ describe("createChannelController", () => {
     });
 
     it("onJumpToPresent reattaches the channel and refetches the live tail", () => {
+      mockMarkChannelRead.mockClear();
       const opts = makeOpts();
       const ctrl = createChannelController(opts);
       ctrl.mountChannel(42, "general");
@@ -596,6 +602,10 @@ describe("createChannelController", () => {
       expect(mockReattachToPresent.mock.invocationCallOrder[0]).toBeLessThan(
         (opts.msgCtrl.loadMessages as ReturnType<typeof vi.fn>).mock.invocationCallOrder[0]!,
       );
+      // OC-0204: clicking "Jump to Present" is reading whatever arrived
+      // below the gap — clear the badge it may have left, the same way
+      // leaving a channel does.
+      expect(mockMarkChannelRead).toHaveBeenCalledWith(42);
     });
 
     it("onRetry re-sends the failed draft with a fresh correlation id", () => {
diff --git a/Client/tauri-client/tests/unit/dispatcher.test.ts b/Client/tauri-client/tests/unit/dispatcher.test.ts
index 354e31d9..e9e38df5 100644
--- a/Client/tauri-client/tests/unit/dispatcher.test.ts
+++ b/Client/tauri-client/tests/unit/dispatcher.test.ts
@@ -20,7 +20,7 @@ import {
 import { membersStore } from "../../src/stores/members.store";
 import { voiceStore } from "../../src/stores/voice.store";
 import { dmStore } from "../../src/stores/dm.store";
-import { blocksStore } from "../../src/stores/blocks.store";
+import { blocksStore, setUserBlockedByMe } from "../../src/stores/blocks.store";
 import {
   emojiStore,
   setCustomEmoji,
@@ -85,6 +85,8 @@ import {
   leaveVoice as mockLeaveVoice,
   disableCamera as mockDisableCamera,
   disableScreenshare as mockDisableScreenshare,
+  isVoiceConnected as mockIsVoiceConnected,
+  handleParticipantLeft as mockHandleParticipantLeft,
 } from "@lib/livekitSession";
 import { rollbackPendingVideo as mockRollbackPendingVideo } from "@lib/screenShare";
 
@@ -376,6 +378,53 @@ describe("WS Dispatcher", () => {
     expect(ch?.unreadCount).toBe(1);
   });
 
+  // OC-0204: "active channel" normally means "the user is watching the live
+  // tail", so skipping the unread bump there is correct — until a jump to an
+  // old permalink/reply/search hit leaves the SAME active channel showing a
+  // detached around-window (messages.store's detachedChannels). addMessage
+  // already refuses to append a live broadcast onto a detached window, so
+  // without also bumping the badge here, a message arriving while the user
+  // reads back-history leaves no row AND no badge — nothing records it ever
+  // arrived.
+  it("wires chat_message to increment unread for the active channel when its window is detached", () => {
+    channelsStore.setState((prev) => {
+      const ch = new Map(prev.channels);
+      ch.set(5, {
+        id: 5,
+        name: "general",
+        type: "text" as const,
+        category: null,
+        position: 0,
+        unreadCount: 0,
+        mentionCount: 0,
+        lastMessageId: null,
+        canSend: true,
+        topic: "",
+        slowMode: 0,
+        nsfw: false,
+        voiceMaxUsers: 0,
+        voiceMaxVideo: 0,
+      });
+      return { ...prev, channels: ch, activeChannelId: 5 }; // channel 5 IS active...
+    });
+    // ...but its loaded window is detached from the live tail (viewing
+    // back-history via a jump).
+    messagesStore.setState((prev) => ({ ...prev, detachedChannels: new Set([5]) }));
+
+    mock.dispatch("chat_message", {
+      id: 200,
+      channel_id: 5,
+      user: { id: 2, username: "bob", avatar: null },
+      content: "ping",
+      reply_to: null,
+      attachments: [],
+      timestamp: "2026-03-15T10:00:00Z",
+    });
+
+    const ch = channelsStore.getState().channels.get(5);
+    expect(ch?.unreadCount).toBe(1);
+  });
+
   describe("chat_message notifications during a reconnect replay burst", () => {
     // The server writes auth_ok before the replay burst, so by the time
     // replayed chat_message frames arrive the client is already "connected"
@@ -2980,6 +3029,44 @@ describe("WS Dispatcher", () => {
     expect([...blocksStore.getState().blockedByMe]).toEqual([11, 22]);
   });
 
+  // OC-0218: the ready-time GET /blocks and a user-initiated block/unblock
+  // (SidebarMemberSection's onToggleBlock -> setUserBlockedByMe, after its
+  // own await api.blockUser/unblockUser) can race. The GET is issued first
+  // but its reply can land after the user's own fresher action — applying it
+  // unconditionally reverts what the user just did.
+  it("does not let a slow-to-resolve ready-time listBlocks revert a fresher local unblock", async () => {
+    cleanup(); // tear down the no-api dispatcher wired in beforeEach
+    let resolveListBlocks!: (v: { blocked_user_ids: number[] }) => void;
+    const listBlocks = vi.fn(
+      () =>
+        new Promise<{ blocked_user_ids: number[] }>((resolve) => {
+          resolveListBlocks = resolve;
+        }),
+    );
+    cleanup = wireDispatcher(mock.ws, { listBlocks });
+
+    // Local user 42 is blocked from a previous session.
+    blocksStore.setState(() => ({ blockedByMe: new Set([42]), blockedByThem: new Set() }));
+
+    // Reconnect: ready fires the GET, which does not resolve yet.
+    mock.dispatch("ready", { channels: [], members: [], voice_states: [], roles: [] });
+    expect(listBlocks).toHaveBeenCalled();
+
+    // While it's in flight, the user clicks "Unblock" on 42 — the same
+    // sequence SidebarMemberSection's onToggleBlock performs once its own
+    // await api.unblockUser resolves.
+    setUserBlockedByMe(42, false);
+    expect([...blocksStore.getState().blockedByMe]).toEqual([]);
+
+    // The GET finally resolves with the stale pre-unblock snapshot.
+    resolveListBlocks({ blocked_user_ids: [42] });
+    await Promise.resolve();
+    await Promise.resolve();
+
+    // The user's unblock must win — 42 must not be silently re-added.
+    expect([...blocksStore.getState().blockedByMe]).toEqual([]);
+  });
+
   it("wires a local transport send failure to mark the pending row failed", () => {
     uiStore.setState((prev) => ({ ...prev, transientError: null }));
 
@@ -3138,6 +3225,34 @@ describe("WS Dispatcher", () => {
       expect(dm?.unreadCount).toBe(0);
     });
 
+    // OC-0204's DM-path sibling: the same "active means watching the live
+    // tail" assumption governs isDmActive here, and breaks the same way when
+    // the active DM's loaded window is detached (a jump to an old permalink/
+    // search hit inside the conversation).
+    it("updates DM last message WITH unread when the active DM's window is detached", () => {
+      channelsStore.setState((prev) => ({ ...prev, activeChannelId: 50 }));
+      authStore.setState((prev) => ({
+        ...prev,
+        user: { id: 5, username: "me", avatar: null, role: "member" },
+      }));
+      messagesStore.setState((prev) => ({ ...prev, detachedChannels: new Set([50]) }));
+
+      mock.dispatch("chat_message", {
+        id: 503,
+        channel_id: 50,
+        user: { id: 10, username: "bob", avatar: "" },
+        content: "arrived while reading back-history",
+        reply_to: null,
+        attachments: [],
+        timestamp: "2026-03-15T10:00:00Z",
+      });
+
+      const dms = dmStore.getState().channels;
+      const dm = dms.find((c) => c.channelId === 50);
+      expect(dm?.lastMessage).toBe("arrived while reading back-history");
+      expect(dm?.unreadCount).toBe(1);
+    });
+
     it("increments the DM mention badge for an incoming @mention", () => {
       channelsStore.setState((prev) => ({ ...prev, activeChannelId: 1 }));
       authStore.setState((prev) => ({
@@ -3676,6 +3791,83 @@ describe("WS Dispatcher", () => {
     expect(voiceLeaveSent).toBe(false);
   });
 
+  // OC-0201: a full-ready resync that preserves a live voice session (the
+  // LiveKit room outlived a WS drop) never replays voice_leave for anyone
+  // who departed the channel while the socket was down — `ready` rebuilds
+  // voiceUsers wholesale and stops. Without reconciliation, a departed peer
+  // keeps a working room key forever (no rotation ever runs for them) and a
+  // client newly elected key holder by the server-side re-registration never
+  // self-elects, since only handleParticipantLeft runs the election.
+  it("reconciles E2EE state for peers who left during a full-ready resync with a live voice session", async () => {
+    vi.mocked(mockHandleParticipantLeft).mockClear();
+
+    authStore.setState(() => ({
+      token: "test-token",
+      user: { id: 42, username: "me", avatar: null, role: "member" },
+      serverName: "Test",
+      motd: "",
+      isAuthenticated: true,
+    }));
+
+    // Before the resync: self (42) and peer (7) are both in channel 10 — the
+    // live LiveKit session survived the WS drop.
+    voiceStore.setState((prev) => ({
+      ...prev,
+      voiceStatus: "connected",
+      currentChannelId: 10,
+      voiceUsers: new Map([
+        [
+          10,
+          new Map([
+            [
+              42,
+              {
+                userId: 42,
+                username: "me",
+                muted: false,
+                deafened: false,
+                speaking: false,
+                camera: false,
+                screenshare: false,
+                serverMuted: false,
+                serverDeafened: false,
+              },
+            ],
+            [
+              7,
+              {
+                userId: 7,
+                username: "departed",
+                muted: false,
+                deafened: false,
+                speaking: false,
+                camera: false,
+                screenshare: false,
+                serverMuted: false,
+                serverDeafened: false,
+              },
+            ],
+          ]),
+        ],
+      ]),
+    }));
+
+    // The full resync's voice_states shows peer 7 has left channel 10 while
+    // we were disconnected — only self remains.
+    mock.dispatch("ready", {
+      channels: [{ id: 1, name: "general", type: "text", category: "", position: 0 }],
+      members: [],
+      voice_states: [{ user_id: 42, channel_id: 10, muted: false, deafened: false }],
+      roles: [],
+      dm_channels: [],
+    });
+    await vi.runAllTimersAsync();
+
+    expect(mockHandleParticipantLeft).toHaveBeenCalledWith(7);
+    // Must never be called for ourselves.
+    expect(mockHandleParticipantLeft).not.toHaveBeenCalledWith(42);
+  });
+
   it("unknown event type does not throw", () => {
     expect(() => {
       mock.dispatch("totally_unknown_server_event", { some: "data" });
@@ -3803,6 +3995,31 @@ describe("WS Dispatcher", () => {
       expect(voiceStore.getState().currentChannelId).toBeNull();
       expect(voiceStore.getState().voiceStatus).toBe("idle");
     });
+
+    // OC-0193: a channel *switch* refusal (precheck FORBIDDEN/BAD_REQUEST/
+    // RATE_LIMITED — anything that lands before the server's self voice_leave
+    // for the OLD channel) optimistically moved currentChannelId to the NEW
+    // channel and voiceStatus to "joining", but the LiveKit room from the OLD
+    // channel is still live — connected, mic published. The store-only
+    // leaveVoiceChannel() rollback used to leave that session dangling: the
+    // widget disappears (currentChannelId null hides it entirely) while audio
+    // keeps flowing and the server still lists us in the old channel. The
+    // rollback must also tear down the live LiveKit session so the media
+    // state and the store agree.
+    it("tears down a still-live LiveKit session when a channel-switch join is refused", async () => {
+      vi.mocked(mockLeaveVoice).mockClear();
+      vi.mocked(mockIsVoiceConnected).mockReturnValue(true);
+      voiceStore.setState((prev) => ({ ...prev, currentChannelId: 7, voiceStatus: "joining" }));
+
+      mock.dispatch("error", { code: "FORBIDDEN", message: "missing CONNECT_VOICE permission" });
+      await vi.runAllTimersAsync();
+
+      expect(mockLeaveVoice).toHaveBeenCalledWith(true);
+      expect(voiceStore.getState().currentChannelId).toBeNull();
+      expect(voiceStore.getState().voiceStatus).toBe("idle");
+
+      vi.mocked(mockIsVoiceConnected).mockReturnValue(false);
+    });
   });
 
   // A server refusal of voice_camera/voice_screenshare (FORBIDDEN,
diff --git a/Client/tauri-client/tests/unit/notifications.test.ts b/Client/tauri-client/tests/unit/notifications.test.ts
index 3ff8dc78..89c8e990 100644
--- a/Client/tauri-client/tests/unit/notifications.test.ts
+++ b/Client/tauri-client/tests/unit/notifications.test.ts
@@ -5,6 +5,7 @@ import { channelsStore } from "../../src/stores/channels.store";
 import { dmStore } from "../../src/stores/dm.store";
 import type { DmChannel } from "../../src/stores/dm.store";
 import { membersStore } from "../../src/stores/members.store";
+import { messagesStore } from "../../src/stores/messages.store";
 import type { ChatMessagePayload } from "../../src/lib/types";
 
 // vi.hoisted ensures testPrefs is available when vi.mock factory runs
@@ -152,6 +153,11 @@ describe("notifyIncomingMessage", () => {
       roleRevision: 0,
     }));
 
+    // A channel marked detached by one test (viewing a back-history
+    // around-window) must not leak into another that expects the plain
+    // active-channel suppression.
+    messagesStore.setState((prev) => ({ ...prev, detachedChannels: new Set() }));
+
     // Ensure document.hasFocus returns false (simulating unfocused window)
     vi.spyOn(document, "hasFocus").mockReturnValue(false);
   });
@@ -1179,6 +1185,34 @@ describe("notifyIncomingMessage", () => {
         expect(sendNotification).toHaveBeenCalled();
       });
     });
+
+    // OC-0204: "active channel" is not the same thing as "the user is
+    // watching the live tail". A jump to an old permalink/reply/search hit
+    // in the active channel opens a detached around-window (messages.store's
+    // detachedChannels) — addMessage refuses to append a live broadcast onto
+    // it, and dispatcher.ts skips the unread bump because the channel is
+    // "active". If this guard also suppresses the notification, an @mention
+    // that arrives while the user reads back-history reaches them through
+    // literally nothing — not even a popup — even though the window is
+    // focused and they are looking at #general.
+    it("proceeds when window focused AND channel matches BUT the window is detached (reading back-history)", async () => {
+      const { sendNotification } = await import("@tauri-apps/plugin-notification");
+      (sendNotification as ReturnType<typeof vi.fn>).mockClear();
+
+      vi.spyOn(document, "hasFocus").mockReturnValue(true);
+      channelsStore.setState((prev) => ({ ...prev, activeChannelId: 1 }));
+      messagesStore.setState((prev) => ({ ...prev, detachedChannels: new Set([1]) }));
+
+      testPrefs.set("desktopNotifications", true);
+      testPrefs.set("flashTaskbar", false);
+      testPrefs.set("notificationSounds", false);
+
+      notifyIncomingMessage(makePayload({ channel_id: 1 }));
+
+      await vi.waitFor(() => {
+        expect(sendNotification).toHaveBeenCalled();
+      });
+    });
   });
 
   describe("notification toggles independently control each action", () => {