Revert the timeline optimistic and pagination rework (#2596)

* Add npm release track invariant and beta dist-tag procedure

* Revert "Keep older chat history and image previews stable (#2490)"

The timeline optimistic/pagination rework needs more work than main releases can wait for. Reverted together with #2484; both are reapplied on integration/timeline-optimistic-rework.

* Revert "Stop completed turns from appearing stuck (#2484)"

See the #2490 revert. #2490 built on this submission-authority change, so the two revert and reapply as a pair.

packages/app/src/panels/agent-panel.tsx

@@ -25,7 +25,6 @@ import { FileDropZone } from "@/components/file-drop/file-drop-zone";
 import { useRetainedPanelActive } from "@/components/retained-panel";
 import { SidebarCallout } from "@/components/sidebar-callout";
 import { Composer } from "@/composer";
-import { getActiveMessageSubmissions } from "@/composer/submission/model";
 import { RewindComposerRestoreProvider } from "@/components/rewind/composer-restore";
 import { getProviderIcon } from "@/components/provider-icons";
 import {
@@ -72,7 +71,7 @@ import { WorkspaceDraftAgentTab } from "@/composer/draft/workspace-tab";
 import { useCreateFlowStore } from "@/stores/create-flow-store";
 import { buildDraftStoreKey, generateDraftId } from "@/stores/draft-keys";
 import { usePanelStore } from "@/stores/panel-store";
-import { selectAgentTimelineState, type Agent, useSessionStore } from "@/stores/session-store";
+import { type Agent, useSessionStore } from "@/stores/session-store";
 import { useWorkspaceLayoutStore } from "@/stores/workspace-layout-store";
 import { buildWorkspaceTabPersistenceKey } from "@/workspace-tabs/model";
 import type { Theme } from "@/styles/theme";
@@ -443,7 +442,6 @@ export function useDraftPanelDescriptor(
 }
 
 const EMPTY_STREAM_ITEMS: StreamItem[] = [];
-const EMPTY_MESSAGE_SUBMISSIONS = [] as const;
 const EMPTY_PENDING_PERMISSIONS = new Map<string, PendingPermission>();
 const EMPTY_PENDING_PERMISSION_LIST: PendingPermission[] = [];
 
@@ -792,12 +790,11 @@ function ChatAgentContent({
   const historySyncGeneration = useSessionStore(
     (state) => state.sessions[serverId]?.historySyncGeneration ?? 0,
   );
-  const replicaTimelineStatus = useSessionStore((state) =>
+  const hasAppliedAuthoritativeHistory = useSessionStore((state) =>
     agentId
-      ? selectAgentTimelineState(state.sessions[serverId], agentId).status
-      : ("cold" as const),
+      ? state.sessions[serverId]?.agentAuthoritativeHistoryApplied?.get(agentId) === true
+      : false,
   );
-  const hasAppliedAuthoritativeHistory = replicaTimelineStatus === "synced";
   const agentHistorySyncGeneration = useSessionStore((state) =>
     agentId ? (state.sessions[serverId]?.agentHistorySyncGeneration?.get(agentId) ?? -1) : -1,
   );
@@ -833,8 +830,7 @@ function ChatAgentContent({
     kind: "idle",
   });
 
-  const hasHydratedHistoryBefore =
-    hasAppliedAuthoritativeHistory || replicaTimelineStatus === "painted";
+  const hasHydratedHistoryBefore = hasAppliedAuthoritativeHistory;
 
   const attentionController = useAgentAttentionClear({
     agentId,
@@ -1292,11 +1288,6 @@ const AgentStreamSection = memo(function AgentStreamSection({
   const streamItemsRaw = useSessionStore((state) =>
     agentId ? state.sessions[serverId]?.agentStreamTail?.get(agentId) : undefined,
   );
-  const pendingMessageSubmissions = useSessionStore((state) =>
-    agentId
-      ? getActiveMessageSubmissions(state.sessions[serverId]?.messageSubmissions.get(agentId))
-      : EMPTY_MESSAGE_SUBMISSIONS,
-  );
   const streamItems = streamItemsRaw ?? EMPTY_STREAM_ITEMS;
   const pendingPermissionList = useStoreWithEqualityFn(
     useSessionStore,
@@ -1336,7 +1327,6 @@ const AgentStreamSection = memo(function AgentStreamSection({
       routeBottomAnchorRequest={routeBottomAnchorRequest}
       isAuthoritativeHistoryReady={hasAppliedAuthoritativeHistory}
       toast={toast}
-      pendingMessageSubmissions={pendingMessageSubmissions}
       onOpenWorkspaceFile={onOpenWorkspaceFile}
     />
   );

packages/app/src/panels/provider-subagent-panel.tsx

@@ -104,12 +104,10 @@ function ProviderSubagentPanel() {
       .catch(() => undefined);
   }, [client, serverId, supported, target.parentAgentId, target.subagentId]);
 
-  const loadOlder = useCallback((): boolean => {
-    if (!client || !supported || isLoadingOlder || !timeline?.hasOlder || !timeline.epoch) {
-      return false;
-    }
+  const loadOlder = useCallback(() => {
+    if (!client || !supported || isLoadingOlder || !timeline?.hasOlder || !timeline.epoch) return;
     const firstSeq = timeline.rows.size ? Math.min(...timeline.rows.keys()) : null;
-    if (firstSeq === null) return false;
+    if (firstSeq === null) return;
     setIsLoadingOlder(true);
     void client
       .fetchProviderSubagentTimeline(target.parentAgentId, target.subagentId, {
@@ -123,7 +121,6 @@ function ProviderSubagentPanel() {
       })
       .catch(() => undefined)
       .finally(() => setIsLoadingOlder(false));
-    return true;
   }, [
     client,
     isLoadingOlder,