diff --git a/apps/client/src/stylesheets/theme-next/shell.css b/apps/client/src/stylesheets/theme-next/shell.css
index 5920ef0e95..3fa23b05a9 100644
--- a/apps/client/src/stylesheets/theme-next/shell.css
+++ b/apps/client/src/stylesheets/theme-next/shell.css
@@ -1259,6 +1259,12 @@ body.layout-horizontal #rest-pane > .classic-toolbar-widget {
 #center-pane .note-split {
     padding-top: 2px;
     background-color: var(--note-split-background-color, var(--main-background-color));
+    transition: border-color 250ms ease-in;
+    border: 1px solid transparent;
+
+    &.active {
+        border-color: var(--link-selection-outline-color);
+    }
 }
 
 body:not(.background-effects) #center-pane .note-split {
diff --git a/apps/client/src/types-pdfjs.d.ts b/apps/client/src/types-pdfjs.d.ts
new file mode 100644
index 0000000000..54a440f162
--- /dev/null
+++ b/apps/client/src/types-pdfjs.d.ts
@@ -0,0 +1,3 @@
+interface Window {
+    TRILIUM_VIEW_HISTORY_STORE?: object;
+}
diff --git a/apps/client/src/widgets/collections/NoteList.tsx b/apps/client/src/widgets/collections/NoteList.tsx
index 5626cc33cf..ec80e6b197 100644
--- a/apps/client/src/widgets/collections/NoteList.tsx
+++ b/apps/client/src/widgets/collections/NoteList.tsx
@@ -11,7 +11,8 @@ import froca from "../../services/froca";
 import { subscribeToMessages, unsubscribeToMessage as unsubscribeFromMessage } from "../../services/ws";
 import { useNoteContext, useNoteLabel, useNoteLabelBoolean, useNoteProperty, useTriliumEvent } from "../react/hooks";
 import { allViewTypes, ViewModeMedia, ViewModeProps, ViewTypeOptions } from "./interface";
-import ViewModeStorage from "./view_mode_storage";
+import ViewModeStorage, { type ViewModeStorageType } from "./view_mode_storage";
+
 interface NoteListProps {
     note: FNote | null | undefined;
     notePath: string | null | undefined;
@@ -215,7 +216,7 @@ export function useNoteIds(note: FNote | null | undefined, viewType: ViewTypeOpt
     return noteIds;
 }
 
-export function useViewModeConfig<T extends object>(note: FNote | null | undefined, viewType: ViewTypeOptions | undefined) {
+export function useViewModeConfig<T extends object>(note: FNote | null | undefined, viewType: ViewModeStorageType | undefined) {
     const [ viewConfig, setViewConfig ] = useState<{
         config: T | undefined;
         storeFn: (data: T) => void;
diff --git a/apps/client/src/widgets/collections/view_mode_storage.ts b/apps/client/src/widgets/collections/view_mode_storage.ts
index 95c3ff8004..b8c3b94f25 100644
--- a/apps/client/src/widgets/collections/view_mode_storage.ts
+++ b/apps/client/src/widgets/collections/view_mode_storage.ts
@@ -4,14 +4,16 @@ import { ViewTypeOptions } from "../collections/interface";
 
 const ATTACHMENT_ROLE = "viewConfig";
 
+export type ViewModeStorageType = ViewTypeOptions | "pdfHistory";
+
 export default class ViewModeStorage<T extends object> {
 
     private note: FNote;
     private attachmentName: string;
 
-    constructor(note: FNote, viewType: ViewTypeOptions) {
+    constructor(note: FNote, viewType: ViewModeStorageType) {
         this.note = note;
-        this.attachmentName = viewType + ".json";
+        this.attachmentName = `${viewType}.json`;
     }
 
     async store(data: T) {
diff --git a/apps/client/src/widgets/containers/split_note_container.ts b/apps/client/src/widgets/containers/split_note_container.ts
index 1cee46b73b..c006775a4e 100644
--- a/apps/client/src/widgets/containers/split_note_container.ts
+++ b/apps/client/src/widgets/containers/split_note_container.ts
@@ -1,10 +1,11 @@
-import FlexContainer from "./flex_container.js";
 import appContext, { type CommandData, type CommandListenerData, type EventData, type EventNames, type NoteSwitchedContext } from "../../components/app_context.js";
-import type BasicWidget from "../basic_widget.js";
 import Component from "../../components/component.js";
+import NoteContext from "../../components/note_context.js";
 import splitService from "../../services/resizer.js";
 import { isMobile } from "../../services/utils.js";
-import NoteContext from "../../components/note_context.js";
+import type BasicWidget from "../basic_widget.js";
+import NoteContextAwareWidget from "../note_context_aware_widget.js";
+import FlexContainer from "./flex_container.js";
 
 interface SplitNoteWidget extends BasicWidget {
     hasBeenAlreadyShown?: boolean;
@@ -74,7 +75,7 @@ export default class SplitNoteContainer extends FlexContainer<SplitNoteWidget> {
 
 
         const subContexts = activeContext.getSubContexts();
-        let noteContext: NoteContext | undefined = undefined;
+        let noteContext: NoteContext | undefined;
         if (isMobile() && subContexts.length > 1) {
             noteContext = subContexts.find(s => s.ntxId !== ntxId);
         }
@@ -201,6 +202,11 @@ export default class SplitNoteContainer extends FlexContainer<SplitNoteWidget> {
 
     async refresh() {
         this.toggleExt(true);
+
+        // Mark the active note context.
+        for (const child of this.children as NoteContextAwareWidget[]) {
+            child.$widget.toggleClass("active", !!child.noteContext?.isActive());
+        }
     }
 
     toggleInt(show: boolean) {} // not needed
@@ -239,16 +245,16 @@ export default class SplitNoteContainer extends FlexContainer<SplitNoteWidget> {
                 widget.hasBeenAlreadyShown = true;
 
                 return [widget.handleEvent("noteSwitched", noteSwitchedContext), this.refreshNotShown(noteSwitchedContext)];
-            } else {
-                return Promise.resolve();
             }
+            return Promise.resolve();
+
         }
 
         if (name === "activeContextChanged") {
             return this.refreshNotShown(data as EventData<"activeContextChanged">);
-        } else {
-            return super.handleEventInChildren(name, data);
         }
+        return super.handleEventInChildren(name, data);
+
     }
 
     refreshNotShown(data: NoteSwitchedContext | EventData<"activeContextChanged">) {
diff --git a/apps/client/src/widgets/type_widgets/File.tsx b/apps/client/src/widgets/type_widgets/File.tsx
index 1871b96c52..0d5b038608 100644
--- a/apps/client/src/widgets/type_widgets/File.tsx
+++ b/apps/client/src/widgets/type_widgets/File.tsx
@@ -16,7 +16,7 @@ export default function FileTypeWidget({ note, parentComponent, noteContext }: T
     if (blob?.content) {
         return <TextPreview content={blob.content} />;
     } else if (note.mime === "application/pdf") {
-        return <PdfPreview blob={blob} note={note} componentId={parentComponent?.componentId} noteContext={noteContext} />;
+        return noteContext && <PdfPreview blob={blob} note={note} componentId={parentComponent?.componentId} noteContext={noteContext} />;
     } else if (note.mime.startsWith("video/")) {
         return <VideoPreview note={note} />;
     } else if (note.mime.startsWith("audio/")) {
diff --git a/apps/client/src/widgets/type_widgets/file/Pdf.tsx b/apps/client/src/widgets/type_widgets/file/Pdf.tsx
index 7b784865f5..e46d64717a 100644
--- a/apps/client/src/widgets/type_widgets/file/Pdf.tsx
+++ b/apps/client/src/widgets/type_widgets/file/Pdf.tsx
@@ -1,6 +1,7 @@
 import { RefObject } from "preact";
 import { useCallback, useEffect, useRef } from "preact/hooks";
 
+import appContext from "../../../components/app_context";
 import type NoteContext from "../../../components/note_context";
 import FBlob from "../../../entities/fblob";
 import FNote from "../../../entities/fnote";
@@ -16,9 +17,9 @@ const VARIABLE_WHITELIST = new Set([
 ]);
 
 export default function PdfPreview({ note, blob, componentId, noteContext }: {
-    note: FNote,
-    noteContext: NoteContext
-    blob: FBlob | null | undefined,
+    note: FNote;
+    noteContext: NoteContext;
+    blob: FBlob | null | undefined;
     componentId: string | undefined;
 }) {
     const iframeRef = useRef<HTMLIFrameElement>(null);
@@ -150,9 +151,28 @@ export default function PdfPreview({ note, blob, componentId, noteContext }: {
         }
     }, [ blob ]);
 
+    // Trigger focus when iframe content is clicked (iframe focus doesn't bubble)
+    useEffect(() => {
+        const iframe = iframeRef.current;
+        if (!iframe) return;
+
+        const handleIframeClick = () => {
+            if (noteContext.ntxId) {
+                appContext.tabManager.activateNoteContext(noteContext.ntxId);
+            }
+        };
+
+        // Listen for clicks on the iframe's content window
+        const iframeDoc = iframe.contentWindow?.document;
+        if (iframeDoc) {
+            iframeDoc.addEventListener('click', handleIframeClick);
+            return () => iframeDoc.removeEventListener('click', handleIframeClick);
+        }
+    }, [ iframeRef.current?.contentWindow, noteContext ]);
 
     return (historyConfig &&
         <iframe
+            tabIndex={300}
             ref={iframeRef}
             class="pdf-preview"
             src={`pdfjs/web/viewer.html?file=../../api/notes/${note.noteId}/open&lang=${locale}&sidebar=${newLayout ? "0" : "1"}`}
@@ -201,7 +221,7 @@ function useStyleInjection(iframeRef: RefObject<HTMLIFrameElement>) {
 
 function getRootCssVariables() {
     const styles = getComputedStyle(document.documentElement);
-    const vars = {};
+    const vars: Record<string, string> = {};
 
     for (let i = 0; i < styles.length; i++) {
         const prop = styles[i];
@@ -213,7 +233,7 @@ function getRootCssVariables() {
     return vars;
 }
 
-function cssVarsToString(vars) {
+function cssVarsToString(vars: Record<string, string>) {
     return `:root {\n${Object.entries(vars)
         .map(([k, v]) => `  ${k}: ${v};`)
         .join('\n')}\n}`;
diff --git a/packages/pdfjs-viewer/src/custom.ts b/packages/pdfjs-viewer/src/custom.ts
index 4f7adbcd7f..919a03d621 100644
--- a/packages/pdfjs-viewer/src/custom.ts
+++ b/packages/pdfjs-viewer/src/custom.ts
@@ -4,8 +4,6 @@ import { setupPdfPages } from "./pages";
 import { setupPdfAttachments } from "./attachments";
 import { setupPdfLayers } from "./layers";
 
-const LOG_EVENT_BUS = false;
-
 async function main() {
     const urlParams = new URLSearchParams(window.location.search);
     if (urlParams.get("sidebar") === "0") {
@@ -20,9 +18,6 @@ async function main() {
     }
     const app = window.PDFViewerApplication;
 
-    if (LOG_EVENT_BUS) {
-        patchEventBus();
-    }
     app.eventBus.on("documentloaded", () => {
         manageSave();
         extractAndSendToc();
@@ -74,7 +69,7 @@ function manageSave() {
             window.parent.postMessage({
                 type: "pdfjs-viewer-document-modified",
                 data: data
-            }, "*");
+            }, window.location.origin);
             storage.resetModified();
             timeout = null;
         }, 2_000);
@@ -93,15 +88,4 @@ function manageSave() {
     });
 }
 
-function patchEventBus() {
-    const eventBus = window.PDFViewerApplication.eventBus;
-    const originalDispatch = eventBus.dispatch.bind(eventBus);
-
-    eventBus.dispatch = (type: string, data?: any) => {
-        console.log("PDF.js event:", type, data);
-        return originalDispatch(type, data);
-    };
-}
-
 main();
-console.log("Custom script loaded");
diff --git a/packages/pdfjs-viewer/src/persistence.ts b/packages/pdfjs-viewer/src/persistence.ts
index 965b5a54b1..7f0110799d 100644
--- a/packages/pdfjs-viewer/src/persistence.ts
+++ b/packages/pdfjs-viewer/src/persistence.ts
@@ -1,4 +1,6 @@
 export default function interceptViewHistory(customOptions?: object) {
+    // We need to monkey-patch the localStorage used by PDF.js to store view history.
+    // Other attempts to intercept the history saving/loading (like overriding methods on PDFViewerApplication) have failed.
     const originalSetItem = Storage.prototype.setItem;
     Storage.prototype.setItem = function (key: string, value: string) {
         if (key === "pdfjs.history") {
@@ -40,7 +42,7 @@ function saveHistory(value: string) {
         window.parent.postMessage({
             type: "pdfjs-viewer-save-view-history",
             data: JSON.stringify(history)
-        }, "*");
+        }, window.location.origin);
         saveTimeout = null;
     }, 2_000);
 }
diff --git a/packages/pdfjs-viewer/tsconfig.app.json b/packages/pdfjs-viewer/tsconfig.app.json
index f6d82c11bd..efdd8ceeac 100644
--- a/packages/pdfjs-viewer/tsconfig.app.json
+++ b/packages/pdfjs-viewer/tsconfig.app.json
@@ -14,7 +14,8 @@
     "tsBuildInfoFile": "dist/tsconfig.app.tsbuildinfo"
   },
   "include": [
-    "src/**/*.ts"
+    "src/**/*.ts",
+    "../../apps/client/src/types-pdfjs.d.ts"
   ],
   "exclude": [
     "eslint.config.js",
@@ -23,7 +24,7 @@
   ],
   "references": [
     {
-      "path": "../commons/tsconfig.app.json"
+      "path": "../commons/tsconfig.lib.json"
     }
   ]
 }
diff --git a/tsconfig.json b/tsconfig.json
index d937096fbc..fb9d2774aa 100644
--- a/tsconfig.json
+++ b/tsconfig.json
@@ -63,6 +63,9 @@
     {
       "path": "./packages/share-theme"
     },
+    {
+      "path": "./packages/pdfjs-viewer"
+    },
     {
       "path": "./scripts"
     }