add speaker notes for slides

frontend/src/components/editor/renderers/slides-layout/slides-layout.tsx

@@ -3,6 +3,7 @@ import React, { useMemo, useState } from "react";
 import { useAtomValue } from "jotai";
 import { numColumnsAtom } from "@/core/cells/cells";
 import type { CellId } from "@/core/cells/ids";
+import { kioskModeAtom } from "@/core/mode";
 import type { ICellRendererProps } from "../types";
 import type { SlidesLayout } from "./types";
 import { computeSlideCellsInfo } from "./compute-slide-cells";
@@ -21,7 +22,10 @@ export const SlidesLayoutRenderer: React.FC<Props> = ({
   cells,
   mode,
 }) => {
-  const isReading = mode === "read";
+  // Kiosk clients (e.g. reveal.js's speaker-view iframes) are read-only and
+  // shouldn't show authoring chrome, so we collapse to the read-mode layout.
+  const kioskMode = useAtomValue(kioskModeAtom);
+  const isReading = mode === "read" || kioskMode;
   const numColumns = useAtomValue(numColumnsAtom);
   const isMultiColumn = numColumns > 1;
   const [activeCellId, setActiveCellId] = useState<CellId | null>(null);
@@ -52,8 +56,8 @@ export const SlidesLayoutRenderer: React.FC<Props> = ({
       activeIndex={resolvedIndex}
       onSlideChange={handleSlideChange}
       configWidth={300}
-      mode={mode}
-      isEditable={mode !== "read"}
+      mode={isReading ? "read" : mode}
+      isEditable={!isReading}
     />
   );
 

frontend/src/components/editor/renderers/slides-layout/types.ts

@@ -27,6 +27,7 @@ export interface SlidesLayout extends Omit<
 export type SlideType = "slide" | "sub-slide" | "fragment" | "skip";
 export interface SlideConfig {
   type?: SlideType;
+  speakerNotes?: string;
 }
 
 export type DeckTransition =

frontend/src/components/slides/__tests__/slide-notes.test.ts

@@ -0,0 +1,130 @@
+/* Copyright 2026 Marimo. All rights reserved. */
+
+import { describe, expect, it } from "vitest";
+import type {
+  SlideConfig,
+  SlideType,
+} from "@/components/editor/renderers/slides-layout/types";
+import type { CellId } from "@/core/cells/ids";
+import { composeSlides } from "../compose-slides";
+import { buildSubslideNotes, collectBlockNotes } from "../slide-notes";
+
+interface Cell {
+  id: CellId;
+  type?: SlideType;
+}
+
+const cell = (id: string, type?: SlideType): Cell => ({
+  id: id as CellId,
+  type,
+});
+
+const configs = (
+  notes: Record<string, string>,
+): ReadonlyMap<CellId, SlideConfig> =>
+  new Map(
+    Object.entries(notes).map(([id, speakerNotes]) => [
+      id as CellId,
+      { speakerNotes } satisfies SlideConfig,
+    ]),
+  );
+
+const firstSubslide = (cells: Cell[]) =>
+  composeSlides({ cells, getType: (c) => c.type ?? "slide" }).stacks[0]
+    .subslides[0];
+
+describe("collectBlockNotes", () => {
+  it("concatenates non-empty notes with paragraph spacing", () => {
+    const result = collectBlockNotes(
+      [cell("a"), cell("b"), cell("c")],
+      configs({ a: "first", b: "", c: "third" }),
+    );
+    expect(result).toBe("first\n\nthird");
+  });
+
+  it("returns an empty string when no cell has notes", () => {
+    expect(collectBlockNotes([cell("a")], configs({}))).toBe("");
+  });
+
+  it("ignores whitespace-only notes", () => {
+    expect(
+      collectBlockNotes([cell("a"), cell("b")], configs({ a: "   ", b: "x" })),
+    ).toBe("x");
+  });
+});
+
+describe("buildSubslideNotes", () => {
+  it("returns empty notes when no cell has any", () => {
+    const subslide = firstSubslide([cell("a"), cell("b", "fragment")]);
+    expect(buildSubslideNotes(subslide, configs({}))).toEqual({
+      slideLevel: "",
+      cumulativeByBlock: new Map(),
+    });
+  });
+
+  it("returns only slide-level notes when there are no fragments", () => {
+    const subslide = firstSubslide([cell("a")]);
+    expect(buildSubslideNotes(subslide, configs({ a: "intro" }))).toEqual({
+      slideLevel: "intro",
+      cumulativeByBlock: new Map(),
+    });
+  });
+
+  it("accumulates fragments below the slide-level notes with a divider", () => {
+    const subslide = firstSubslide([
+      cell("a"),
+      cell("b", "fragment"),
+      cell("c", "fragment"),
+    ]);
+    const { slideLevel, cumulativeByBlock } = buildSubslideNotes(
+      subslide,
+      configs({ a: "intro", b: "step one", c: "step two" }),
+    );
+    expect(slideLevel).toBe("intro");
+    expect(cumulativeByBlock.get(1)).toBe("intro\n\n---\n\nstep one");
+    expect(cumulativeByBlock.get(2)).toBe(
+      "intro\n\n---\n\nstep one\n\n---\n\nstep two",
+    );
+  });
+
+  it("accumulates fragments with no slide-level notes", () => {
+    const subslide = firstSubslide([
+      cell("a"),
+      cell("b", "fragment"),
+      cell("c", "fragment"),
+    ]);
+    const { slideLevel, cumulativeByBlock } = buildSubslideNotes(
+      subslide,
+      configs({ b: "first reveal", c: "second reveal" }),
+    );
+    expect(slideLevel).toBe("");
+    expect(cumulativeByBlock.get(1)).toBe("first reveal");
+    expect(cumulativeByBlock.get(2)).toBe(
+      "first reveal\n\n---\n\nsecond reveal",
+    );
+  });
+
+  it("skips empty fragments without leaving dangling dividers", () => {
+    const subslide = firstSubslide([
+      cell("a"),
+      cell("b", "fragment"),
+      cell("c", "fragment"),
+    ]);
+    const { cumulativeByBlock } = buildSubslideNotes(
+      subslide,
+      configs({ a: "intro", c: "third" }),
+    );
+    expect(cumulativeByBlock.get(1)).toBe("intro");
+    expect(cumulativeByBlock.get(2)).toBe("intro\n\n---\n\nthird");
+  });
+
+  it("returns no cumulative entries when fragments and slide have no notes", () => {
+    const subslide = firstSubslide([
+      cell("a"),
+      cell("b", "fragment"),
+      cell("c", "fragment"),
+    ]);
+    const { cumulativeByBlock } = buildSubslideNotes(subslide, configs({}));
+    expect(cumulativeByBlock.size).toBe(0);
+  });
+});