fix: Eliminate content page flickering from layout shifts and double invalidation

- Reserve fixed height for "Saving..." indicator instead of conditionally
  rendering it, preventing layout shift on every auto-save cycle
- Remove getPage from updatePage mutation cache invalidation — useAutoSave
  already handles optimistic updates, and SSE events cover external changes.
  This eliminates double-invalidation (mutation + SSE) refetch storms.
- Memoize TiptapEditor extensions array to avoid recreating extensions and
  pageLinkDeletionDetector on every render
- Memoize useLiveUpdates rules array in initiative detail page

apps/web/src/components/editor/ContentTab.tsx

@@ -253,13 +253,13 @@ export function ContentTab({ initiativeId, initiativeName }: ContentTabProps) {
 
           {resolvedActivePageId && (
             <>
-              {(isSaving || updateInitiativeMutation.isPending) && (
-                <div className="flex justify-end mb-2">
+              <div className="flex justify-end mb-2 h-4">
+                {(isSaving || updateInitiativeMutation.isPending) && (
                   <span className="text-xs text-muted-foreground">
                     Saving...
                   </span>
-                </div>
-              )}
+                )}
+              </div>
               {activePageQuery.isSuccess && (
                 <input
                   value={pageTitle}

apps/web/src/components/editor/TiptapEditor.tsx

@@ -1,4 +1,4 @@
-import { useEffect, useRef, useCallback } from "react";
+import { useEffect, useRef, useCallback, useMemo } from "react";
 import { useEditor, EditorContent } from "@tiptap/react";
 import type { Editor } from "@tiptap/react";
 import StarterKit from "@tiptap/starter-kit";
@@ -36,33 +36,33 @@ export function TiptapEditor({
   const onPageLinkDeletedRef = useRef(onPageLinkDeleted);
   onPageLinkDeletedRef.current = onPageLinkDeleted;
 
-  const pageLinkDeletionDetector = createPageLinkDeletionDetector(onPageLinkDeletedRef);
-
-  const baseExtensions = [
-    StarterKit,
-    Table.configure({ resizable: true, cellMinWidth: 50 }),
-    TableRow,
-    TableCell,
-    TableHeader,
-    Placeholder.configure({
-      includeChildren: true,
-      placeholder: ({ node }) => {
-        if (node.type.name === 'heading') {
-          return `Heading ${node.attrs.level}`;
-        }
-        return "Type '/' for commands...";
-      },
-    }),
-    Link.configure({
-      openOnClick: false,
-    }),
-    SlashCommands,
-    BlockSelectionExtension,
-  ];
-
-  const extensions = enablePageLinks
-    ? [...baseExtensions, PageLinkExtension, pageLinkDeletionDetector]
-    : baseExtensions;
+  const extensions = useMemo(() => {
+    const detector = createPageLinkDeletionDetector(onPageLinkDeletedRef);
+    const base = [
+      StarterKit,
+      Table.configure({ resizable: true, cellMinWidth: 50 }),
+      TableRow,
+      TableCell,
+      TableHeader,
+      Placeholder.configure({
+        includeChildren: true,
+        placeholder: ({ node }) => {
+          if (node.type.name === 'heading') {
+            return `Heading ${node.attrs.level}`;
+          }
+          return "Type '/' for commands...";
+        },
+      }),
+      Link.configure({
+        openOnClick: false,
+      }),
+      SlashCommands,
+      BlockSelectionExtension,
+    ];
+    return enablePageLinks
+      ? [...base, PageLinkExtension, detector]
+      : base;
+  }, [enablePageLinks]);
 
   const editor = useEditor(
     {

apps/web/src/lib/invalidation.ts

@@ -71,7 +71,11 @@ const INVALIDATION_MAP: Partial<Record<MutationName, QueryName[]>> = {
   revertChangeSet: ["listPhases", "listPhaseTasks", "listInitiativeTasks", "listPages", "getPage", "listChangeSets", "getRootPage", "getChangeSet"],
 
   // --- Pages ---
-  updatePage: ["listPages", "getPage", "getRootPage"],
+  // NOTE: getPage omitted — useAutoSave handles optimistic updates for the
+  // active page, and SSE `page:updated` events cover external changes.
+  // Including getPage here caused double-invalidation (mutation + SSE) and
+  // refetch storms that flickered the editor.
+  updatePage: ["listPages", "getRootPage"],
   createPage: ["listPages", "getRootPage"],
   deletePage: ["listPages", "getRootPage"],
 

apps/web/src/routes/initiatives/$id.tsx

@@ -1,3 +1,4 @@
+import { useMemo } from "react";
 import { createFileRoute, useNavigate } from "@tanstack/react-router";
 import { motion } from "motion/react";
 import { AlertCircle } from "lucide-react";
@@ -11,6 +12,7 @@ import { ExecutionTab } from "@/components/ExecutionTab";
 import { ReviewTab } from "@/components/review";
 import { PipelineTab } from "@/components/pipeline";
 import { useLiveUpdates } from "@/hooks";
+import type { LiveUpdateRule } from "@/hooks/useLiveUpdates";
 
 type Tab = "content" | "plan" | "execution" | "review";
 const TABS: Tab[] = ["content", "plan", "execution", "review"];
@@ -27,15 +29,16 @@ function InitiativeDetailPage() {
   const { tab: activeTab } = Route.useSearch();
   const navigate = useNavigate();
 
-  // Single SSE stream for all live updates
-  useLiveUpdates([
+  // Single SSE stream for all live updates — memoized to avoid re-subscribe on render
+  const liveUpdateRules = useMemo<LiveUpdateRule[]>(() => [
     { prefix: 'task:',      invalidate: ['listPhases', 'listTasks', 'listInitiativeTasks', 'getPhaseDependencies', 'listPhaseTaskDependencies'] },
     { prefix: 'phase:',     invalidate: ['listPhases', 'listTasks', 'listInitiativePhaseDependencies', 'getPhaseDependencies'] },
     { prefix: 'agent:',     invalidate: ['listAgents', 'getActiveRefineAgent'] },
     { prefix: 'page:',      invalidate: ['listPages', 'getPage', 'getRootPage'] },
     { prefix: 'changeset:', invalidate: ['getChangeSet', 'listChangeSets'] },
     { prefix: 'preview:',   invalidate: ['listPreviews', 'getPreviewStatus'] },
-  ]);
+  ], []);
+  useLiveUpdates(liveUpdateRules);
 
   // tRPC queries
   const initiativeQuery = trpc.getInitiative.useQuery({ id });