diff --git a/.github/copilot-instructions.md b/.github/copilot-instructions.md
index 8f87f6a166..fad12709d3 100644
--- a/.github/copilot-instructions.md
+++ b/.github/copilot-instructions.md
@@ -338,6 +338,16 @@ Trilium provides powerful user scripting capabilities:
 - **Server-side**: `import { t } from "i18next"` with keys in `apps/server/src/assets/translations/en/server.json`
 - **Interpolation**: Use `{{variable}}` for normal interpolation; use `{{- variable}}` (with hyphen) for **unescaped** interpolation when the value contains special characters like quotes that shouldn't be HTML-escaped
 
+### Storing User Preferences
+- **Do not use `localStorage`** for user preferences — Trilium has a synced options system that persists across devices
+- To add a new user preference:
+  1. Add the option type to `OptionDefinitions` in `packages/commons/src/lib/options_interface.ts`
+  2. Add a default value in `apps/server/src/services/options_init.ts` in the `defaultOptions` array
+  3. **Whitelist the option** in `apps/server/src/routes/api/options.ts` by adding it to `ALLOWED_OPTIONS` (required for client updates)
+  4. Use `useTriliumOption("optionName")` hook in React components to read/write the option
+- Available hooks: `useTriliumOption` (string), `useTriliumOptionBool`, `useTriliumOptionInt`, `useTriliumOptionJson`
+- See `docs/Developer Guide/Developer Guide/Concepts/Options/Creating a new option.md` for detailed documentation
+
 ## Testing Conventions
 
 - **Write concise tests**: Group related assertions together in a single test case rather than creating many one-shot tests
diff --git a/CLAUDE.md b/CLAUDE.md
index ab6067e058..1b90b02881 100644
--- a/CLAUDE.md
+++ b/CLAUDE.md
@@ -157,6 +157,16 @@ Trilium provides powerful user scripting capabilities:
 - **Do not use `crypto.randomUUID()`** or other Web Crypto APIs that require secure contexts - Trilium can run over HTTP, not just HTTPS
 - Use `randomString()` from `apps/client/src/services/utils.ts` for generating IDs instead
 
+### Storing User Preferences
+- **Do not use `localStorage`** for user preferences — Trilium has a synced options system that persists across devices
+- To add a new user preference:
+  1. Add the option type to `OptionDefinitions` in `packages/commons/src/lib/options_interface.ts`
+  2. Add a default value in `apps/server/src/services/options_init.ts` in the `defaultOptions` array
+  3. **Whitelist the option** in `apps/server/src/routes/api/options.ts` by adding it to `ALLOWED_OPTIONS` (required for client updates)
+  4. Use `useTriliumOption("optionName")` hook in React components to read/write the option
+- Available hooks: `useTriliumOption` (string), `useTriliumOptionBool`, `useTriliumOptionInt`, `useTriliumOptionJson`
+- See `docs/Developer Guide/Developer Guide/Concepts/Options/Creating a new option.md` for detailed documentation
+
 ### Shared Types Policy
 - Types shared between client and server belong in `@triliumnext/commons` (`packages/commons/src/lib/`)
 - Import shared types directly from `@triliumnext/commons` - do not re-export them from app-specific modules
diff --git a/apps/client/src/widgets/dialogs/include_note.tsx b/apps/client/src/widgets/dialogs/include_note.tsx
index c8f818302d..74d41da6be 100644
--- a/apps/client/src/widgets/dialogs/include_note.tsx
+++ b/apps/client/src/widgets/dialogs/include_note.tsx
@@ -8,7 +8,7 @@ import Button from "../react/Button";
 import { Suggestion, triggerRecentNotes } from "../../services/note_autocomplete";
 import tree from "../../services/tree";
 import froca from "../../services/froca";
-import { useTriliumEvent } from "../react/hooks";
+import { useTriliumEvent, useTriliumOption } from "../react/hooks";
 import { type BoxSize, CKEditorApi } from "../type_widgets/text/CKEditorWithWatchdog";
 
 export interface IncludeNoteOpts {
@@ -18,11 +18,13 @@ export interface IncludeNoteOpts {
 export default function IncludeNoteDialog() {
     const editorApiRef = useRef<CKEditorApi>(null);
     const [suggestion, setSuggestion] = useState<Suggestion | null>(null);
-    const [boxSize, setBoxSize] = useState<string>("medium");
+    const [defaultBoxSize, setDefaultBoxSize] = useTriliumOption("includeNoteDefaultBoxSize");
+    const [boxSize, setBoxSize] = useState<string>(defaultBoxSize);
     const [shown, setShown] = useState(false);
 
     useTriliumEvent("showIncludeNoteDialog", ({ editorApi }) => {
         editorApiRef.current = editorApi;
+        setBoxSize(defaultBoxSize); // Reset to default when opening dialog
         setShown(true);
     });
 
@@ -35,10 +37,14 @@ export default function IncludeNoteDialog() {
             size="lg"
             onShown={() => triggerRecentNotes(autoCompleteRef.current)}
             onHidden={() => setShown(false)}
-            onSubmit={() => {
+            onSubmit={async () => {
                 if (!suggestion?.notePath || !editorApiRef.current) return;
                 setShown(false);
-                includeNote(suggestion.notePath, editorApiRef.current, boxSize as BoxSize);
+                await includeNote(suggestion.notePath, editorApiRef.current, boxSize as BoxSize);
+                // Save the selected box size as the new default
+                if (boxSize !== defaultBoxSize) {
+                    setDefaultBoxSize(boxSize);
+                }
             }}
             footer={<Button text={t("include_note.button_include")} keyboardShortcut="Enter" />}
             show={shown}
diff --git a/apps/server/src/routes/api/options.ts b/apps/server/src/routes/api/options.ts
index 912fef055e..e39cf7dc7f 100644
--- a/apps/server/src/routes/api/options.ts
+++ b/apps/server/src/routes/api/options.ts
@@ -95,6 +95,7 @@ const ALLOWED_OPTIONS = new Set<OptionNames>([
     "textNoteEmojiCompletionEnabled",
     "textNoteCompletionEnabled",
     "textNoteSlashCommandsEnabled",
+    "includeNoteDefaultBoxSize",
     "layoutOrientation",
     "backgroundEffects",
     "allowedHtmlTags",
diff --git a/apps/server/src/services/options_init.ts b/apps/server/src/services/options_init.ts
index 22c39fbe2a..e15e26ad00 100644
--- a/apps/server/src/services/options_init.ts
+++ b/apps/server/src/services/options_init.ts
@@ -223,6 +223,7 @@ const defaultOptions: DefaultOption[] = [
     { name: "textNoteEmojiCompletionEnabled", value: "true", isSynced: true },
     { name: "textNoteCompletionEnabled", value: "true", isSynced: true },
     { name: "textNoteSlashCommandsEnabled", value: "true", isSynced: true },
+    { name: "includeNoteDefaultBoxSize", value: "medium", isSynced: true },
 
     // HTML import configuration
     { name: "layoutOrientation", value: "vertical", isSynced: false },
diff --git a/packages/commons/src/lib/options_interface.ts b/packages/commons/src/lib/options_interface.ts
index 08ab1ea45f..da6d9b7f01 100644
--- a/packages/commons/src/lib/options_interface.ts
+++ b/packages/commons/src/lib/options_interface.ts
@@ -142,6 +142,9 @@ export interface OptionDefinitions extends KeyboardShortcutsOptions<KeyboardActi
     seenCallToActions: string;
     experimentalFeatures: string;
 
+    // Include note settings
+    includeNoteDefaultBoxSize: "small" | "medium" | "full" | "expandable";
+
     // AI / LLM
     /** JSON array of configured LLM providers with their API keys */
     llmProviders: string;