diff --git a/.beads/interactions.jsonl b/.beads/interactions.jsonl
index ac6b95f..adcb02a 100644
--- a/.beads/interactions.jsonl
+++ b/.beads/interactions.jsonl
@@ -30,3 +30,4 @@
 {"id":"int-a54950bb4a7dbb177188a5ec02e9d9fd","kind":"field_change","created_at":"2026-09-11T06:50:28.175047619Z","actor":"Shinuwa","issue_id":"sokko-g-328","extra":{"field":"status","new_value":"closed","old_value":"in_progress","reason":"Default E2E concurrency capped at two workers with failure traces; compact calendar titles kept in flow and sm padding corrected. Desktop/mobile geometry and editing regressions added. npm run check:full passed; second full E2E run passed all 17 tests without retries."}}
 {"id":"int-147c4573ce40577c21afec08775c2811","kind":"field_change","created_at":"2026-09-11T07:16:09.749977471Z","actor":"Shinuwa","issue_id":"sokko-g-55a","extra":{"field":"status","new_value":"closed","old_value":"in_progress","reason":"Restored recommended purity lint; initialized alert clock in effect; removed post-commit draft synchronization from shared inline editing and reused it in Randomizer. 100 Node tests, lint, production build and all 19 E2E pass. StrictMode hook tests cover input/contentEditable, source updates, commit and Escape; broader C10 tracked in sokko-g-8po."}}
 {"id":"int-f9e84a155b896c7f68c83ee2454f904d","kind":"field_change","created_at":"2026-09-11T11:56:43.680278965Z","actor":"Shinuwa","issue_id":"sokko-g-sc7","extra":{"field":"status","new_value":"closed","old_value":"in_progress","reason":"Reproduced memo draft loss on notification, isolated per-memo drafts using useInlineEdit, preserved multiline/trim/delete behavior. Goal Tree reconciles selection and valid tabs before DOM commit with StrictMode regressions. npm run check:full passed: 100 Node tests and 21 E2E."}}
+{"id":"int-4b64d68baf132fa99cb3244d8487034c","kind":"field_change","created_at":"2026-09-11T12:05:04.580370366Z","actor":"Shinuwa","issue_id":"sokko-g-kqo","extra":{"field":"status","new_value":"closed","old_value":"in_progress","reason":"Shared keyed state initializes Notepad/ImageAnnotation temporary drawings and RNG history before DOM commit; ignores setters bound to a different active key. Storage keys and write/error paths preserved. npm run check:full passed: 100 Node tests and 23 E2E including StrictMode key switches and real Notepad canvas/page/reload checks."}}
diff --git a/docs/FEATURE_CHECKLIST.md b/docs/FEATURE_CHECKLIST.md
index d6c6bc5..2925eb7 100644
--- a/docs/FEATURE_CHECKLIST.md
+++ b/docs/FEATURE_CHECKLIST.md
@@ -18,6 +18,7 @@ Checklist à suivre lors de l'ajout ou de la modification d'un outil, d'une page
 - Vérifier l'affichage dans la page toolbox complète.
 - Vérifier l'affichage dans le panneau latéral.
 - Pour le Bloc Note, vérifier la sélection, l'ajout, le renommage et la suppression de pages en page complète, panneau latéral et mobile.
+- Pour les dessins temporaires et l'historique du simulateur de chance, vérifier l'isolation par clé de session lors des changements de page/outil et après rechargement ; une navigation seule ne doit pas écraser les données de l'autre clé.
 - Pour Mémos, vérifier l'édition courte, les couleurs, la réorganisation et la bande déroulante.
 - Vérifier qu'une notification ou une mise à jour sans rapport ne remplace pas un brouillon Mémos avant sa validation au blur.
 - Pour l'arbre d'objectifs, vérifier la sélection après suppression/import et le retour à Base quand le nœud sélectionné devient une étape sans onglet Contenu.
diff --git a/e2e/fixtures/keyed-state-probe.js b/e2e/fixtures/keyed-state-probe.js
new file mode 100644
index 0000000..d300276
--- /dev/null
+++ b/e2e/fixtures/keyed-state-probe.js
@@ -0,0 +1,38 @@
+// Rôle : observe les valeurs validées et les setters différés d'un état lié à une clé.
+/* global sessionStorage */
+import { createElement, StrictMode, useLayoutEffect } from "react";
+import { createRoot } from "react-dom/client";
+import { flushSync } from "react-dom";
+import { useKeyedState } from "../../website/src/hooks/useKeyedState.js";
+
+export function mountKeyedStateProbe(element) {
+  const root = createRoot(element);
+  const snapshots = [];
+  const setters = new Map();
+  let reads = 0;
+
+  function Probe({ identity }) {
+    const [value, setValue] = useKeyedState(identity, (key) => {
+      reads++;
+      return JSON.parse(sessionStorage.getItem(`keyed-probe:${key}`) || "[]");
+    });
+    useLayoutEffect(() => {
+      snapshots.push({ key: identity, value });
+      setters.set(identity, setValue);
+    });
+    return createElement("output", null, JSON.stringify(value));
+  }
+
+  function update(identity) {
+    snapshots.length = 0;
+    flushSync(() => root.render(createElement(StrictMode, null, createElement(Probe, { identity }))));
+  }
+  update("a");
+  return {
+    update,
+    snapshots,
+    get reads() { return reads; },
+    append: (key, value) => flushSync(() => setters.get(key)((current) => [...current, value])),
+    unmount: () => root.unmount()
+  };
+}
diff --git a/e2e/session-state.spec.js b/e2e/session-state.spec.js
new file mode 100644
index 0000000..58a35c8
--- /dev/null
+++ b/e2e/session-state.spec.js
@@ -0,0 +1,92 @@
+// Rôle : vérifie l'isolation de l'état de session et des dessins entre pages du Bloc Note.
+/* global window, document, sessionStorage */
+import { test, expect } from "@playwright/test";
+import { fileURLToPath, URL } from "node:url";
+import { resetSokkoStorage } from "./helpers/storage.js";
+
+const probeUrl = `/@fs/${fileURLToPath(new URL("./fixtures/keyed-state-probe.js", import.meta.url))}`;
+
+test("keyed state never commits another key's value under StrictMode", async ({ page }) => {
+  const errors = [];
+  page.on("pageerror", (error) => errors.push(error.message));
+  await page.goto("/");
+  await page.evaluate(async (url) => {
+    sessionStorage.setItem("keyed-probe:a", '["A"]');
+    sessionStorage.setItem("keyed-probe:b", '["B"]');
+    const { mountKeyedStateProbe } = await import(url);
+    const element = document.createElement("div");
+    document.body.prepend(element);
+    window.keyedProbe = mountKeyedStateProbe(element);
+  }, probeUrl);
+  await page.evaluate(() => window.keyedProbe.append("a", "edit"));
+  const reads = await page.evaluate(() => window.keyedProbe.reads);
+  await page.evaluate(() => window.keyedProbe.update("a"));
+  expect(await page.evaluate(() => window.keyedProbe.reads)).toBe(reads);
+  expect(await page.evaluate(() => window.keyedProbe.snapshots.at(-1).value)).toEqual(["A", "edit"]);
+
+  await page.evaluate(() => window.keyedProbe.update("b"));
+  const snapshots = await page.evaluate(() => window.keyedProbe.snapshots);
+  expect(snapshots.length).toBeGreaterThan(0);
+  for (const snapshot of snapshots) expect(snapshot).toEqual({ key: "b", value: ["B"] });
+  await page.evaluate(() => window.keyedProbe.append("a", "stale"));
+  await page.evaluate(() => window.keyedProbe.append("b", "current"));
+  expect(await page.evaluate(() => window.keyedProbe.snapshots.at(-1).value)).toEqual(["B", "current"]);
+  await page.evaluate(() => window.keyedProbe.update("a"));
+  expect(await page.evaluate(() => window.keyedProbe.snapshots.at(-1).value)).toEqual(["A"]);
+  await page.evaluate(() => window.keyedProbe.unmount());
+  expect(errors).toEqual([]);
+});
+
+test("notepad temporary drawings stay on their own pages and survive reload", async ({ page }) => {
+  const errors = [];
+  page.on("pageerror", (error) => errors.push(error.message));
+  await resetSokkoStorage(page);
+  await page.evaluate(async () => {
+    const db = await import("/src/utils/indexedDbStorage.js");
+    await db.setToolboxSnapshot([{
+      id: "session-notes", name: "Session notes", modules: [{ id: "note", type: "notepad" }]
+    }], {}, {
+      "session-notes:note": {
+        activePageId: "a",
+        pages: ["a", "b", "c"].map((id) => ({
+          id, title: `Page ${id}`, html: `<p>Content ${id}</p>`, drawingMode: "temporary"
+        }))
+      }
+    });
+    for (const [id, y, color] of [["a", 20, "#f6c453"], ["b", 40, "#22d3ee"]]) {
+      sessionStorage.setItem(`sokkog:notepad-drawings:session-notes:note:${id}`, JSON.stringify([
+        { id, color, width: 4, points: [{ x: 20, y }, { x: 100, y }] }
+      ]));
+    }
+    sessionStorage.setItem("sokkog:notepad-drawings:session-notes:note:c", "invalid json");
+  });
+  await page.goto("/#/toolbox/session-notes");
+  await page.reload();
+  const notepad = page.locator('[data-module-type="notepad"]');
+  const canvas = notepad.locator("canvas");
+  const alphaAt = (y) => canvas.evaluate((element, y) => {
+    const ratio = element.width / element.clientWidth;
+    return element.getContext("2d").getImageData(Math.round(50 * ratio), Math.round(y * ratio), 1, 1).data[3];
+  }, y);
+  async function selectPage(id) {
+    await notepad.getByRole("button", { name: "Afficher les pages du Bloc Note", exact: true }).click();
+    await page.getByRole("button", { name: `Page ${id}`, exact: true }).click();
+    await expect(notepad.locator(".notepad-editor")).toHaveText(`Content ${id}`);
+  }
+  await expect(canvas).toBeVisible();
+  await expect.poll(() => alphaAt(20)).toBeGreaterThan(0);
+  await selectPage("b");
+  await expect.poll(() => alphaAt(40)).toBeGreaterThan(0);
+  await expect.poll(() => alphaAt(20)).toBe(0);
+  await notepad.getByRole("button", { name: "Dessiner", exact: true }).click();
+  await notepad.getByRole("button", { name: "Effacer les dessins", exact: true }).click();
+  await expect.poll(() => page.evaluate(() => JSON.parse(sessionStorage.getItem("sokkog:notepad-drawings:session-notes:note:b")))).toEqual([]);
+  await selectPage("a");
+  await expect.poll(() => alphaAt(20)).toBeGreaterThan(0);
+  await selectPage("c");
+  await expect.poll(() => alphaAt(20)).toBe(0);
+  await selectPage("a");
+  await page.reload();
+  await expect.poll(() => alphaAt(20)).toBeGreaterThan(0);
+  expect(errors).toEqual([]);
+});
diff --git a/website/src/features/toolboxes/modules/ImageAnnotationModule.jsx b/website/src/features/toolboxes/modules/ImageAnnotationModule.jsx
index 79696ff..1c8d0f7 100644
--- a/website/src/features/toolboxes/modules/ImageAnnotationModule.jsx
+++ b/website/src/features/toolboxes/modules/ImageAnnotationModule.jsx
@@ -4,6 +4,16 @@ import { Icon } from "../../../components/Icon.jsx";
 import { Tooltip } from "../../../components/Tooltip.jsx";
 import { DrawingOverlay } from "./DrawingOverlay.jsx";
 import { TextExchangeActions } from "./TextExchangeActions.jsx";
+import { useKeyedState } from "../../../hooks/useKeyedState.js";
+
+function readTemporaryDrawings(sessionKey) {
+  try {
+    const stored = JSON.parse(sessionStorage.getItem(sessionKey) || "null");
+    return Array.isArray(stored?.strokes) ? stored : { strokes: [] };
+  } catch {
+    return { strokes: [] };
+  }
+}
 
 function markerLabel(index, marker, textContent) {
   return marker.label || `${textContent.markerPrefix || "Marqueur"} ${index + 1}`;
@@ -19,7 +29,7 @@ export function ImageAnnotationModule({ toolboxId, moduleId, context, editing, t
   const sessionKey = `sokkog:image-annotation-drawings:${toolboxId}:${moduleId}`;
   const [dragOver, setDragOver] = useState(false);
   const [drawingMode, setDrawingMode] = useState("permanent");
-  const [temporaryDrawings, setTemporaryDrawings] = useState({ strokes: [] });
+  const [temporaryDrawings, setTemporaryDrawings] = useKeyedState(sessionKey, readTemporaryDrawings);
   const markers = data.markers;
   const drawings = drawingMode === "permanent" ? data.drawings || { strokes: [] } : temporaryDrawings;
   const pastePlaceholder = textContent.pastePlaceholder || "Coller une image ici";
@@ -31,12 +41,6 @@ export function ImageAnnotationModule({ toolboxId, moduleId, context, editing, t
   useEffect(() => {
     temporaryDrawingsDirtyRef.current = false;
     sessionStorageFailureRef.current = "";
-    try {
-      const stored = JSON.parse(sessionStorage.getItem(sessionKey) || "{\"strokes\":[]}");
-      setTemporaryDrawings(stored?.strokes ? stored : { strokes: [] });
-    } catch {
-      setTemporaryDrawings({ strokes: [] });
-    }
   }, [sessionKey]);
 
   useEffect(() => {
diff --git a/website/src/features/toolboxes/modules/NotepadModule.jsx b/website/src/features/toolboxes/modules/NotepadModule.jsx
index adc8d57..a62ca8d 100644
--- a/website/src/features/toolboxes/modules/NotepadModule.jsx
+++ b/website/src/features/toolboxes/modules/NotepadModule.jsx
@@ -7,6 +7,7 @@ import { DrawingOverlay } from "./DrawingOverlay.jsx";
 import { NotepadToolbar } from "./NotepadToolbar.jsx";
 import { TextExchangeActions } from "./TextExchangeActions.jsx";
 import { normalizeNotepadData } from "../storage/toolboxStorage.js";
+import { useKeyedState } from "../../../hooks/useKeyedState.js";
 import {
   DRAWING_WIDTHS,
   HIGHLIGHT_COLORS,
@@ -22,6 +23,15 @@ import {
 
 const EMPTY_NOTEPAD_DATA = { text: "" };
 
+function readTemporaryStrokes(sessionKey) {
+  try {
+    const stored = JSON.parse(sessionStorage.getItem(sessionKey) || "[]");
+    return Array.isArray(stored) ? stored : [];
+  } catch {
+    return [];
+  }
+}
+
 export function NotepadModule({ toolboxId, moduleId, context, textExchangeOpen }) {
   const storedData = context.getModuleData(toolboxId, moduleId, EMPTY_NOTEPAD_DATA);
   const normalizedData = useMemo(() => normalizeNotepadData(storedData), [storedData]);
@@ -58,7 +68,7 @@ export function NotepadModule({ toolboxId, moduleId, context, textExchangeOpen }
     numberList: false
   });
   const sessionKey = `sokkog:notepad-drawings:${toolboxId}:${moduleId}:${activePage.id}`;
-  const [temporaryStrokes, setTemporaryStrokes] = useState([]);
+  const [temporaryStrokes, setTemporaryStrokes] = useKeyedState(sessionKey, readTemporaryStrokes);
 
   useEffect(() => {
     notepadDataRef.current = normalizedData;
@@ -122,12 +132,6 @@ export function NotepadModule({ toolboxId, moduleId, context, textExchangeOpen }
   useEffect(() => {
     temporaryStrokesDirtyRef.current = false;
     sessionStorageFailureRef.current = "";
-    try {
-      const stored = JSON.parse(sessionStorage.getItem(sessionKey) || "[]");
-      setTemporaryStrokes(Array.isArray(stored) ? stored : []);
-    } catch {
-      setTemporaryStrokes([]);
-    }
   }, [sessionKey]);
 
   useEffect(() => {
diff --git a/website/src/features/toolboxes/modules/RngSimulatorModule.jsx b/website/src/features/toolboxes/modules/RngSimulatorModule.jsx
index 918acb2..2515ea6 100644
--- a/website/src/features/toolboxes/modules/RngSimulatorModule.jsx
+++ b/website/src/features/toolboxes/modules/RngSimulatorModule.jsx
@@ -3,6 +3,7 @@ import { useEffect, useMemo, useRef, useState } from "react";
 import { Icon } from "../../../components/Icon.jsx";
 import { Tabs } from "../../../components/Tabs.jsx";
 import { useDraftForm } from "../../../hooks/useDraftForm.js";
+import { useKeyedState } from "../../../hooks/useKeyedState.js";
 import { TextExchangeActions } from "./TextExchangeActions.jsx";
 import {
   RNG_SIMULATOR_DEFAULT_RATE,
@@ -156,7 +157,7 @@ export function RngSimulatorModule({ toolboxId, moduleId, context, editing = fal
   ], [textContent.forecastsTabLabel, textContent.simulationTabLabel, textContent.trackingTabLabel]);
   const historyStorageKey = `rng-simulator:${toolboxId}:${moduleId}:history`;
   const [activeTab, setActiveTab] = useState("tracking");
-  const [history, setHistory] = useState(() => readSimulationHistory(historyStorageKey));
+  const [history, setHistory] = useKeyedState(historyStorageKey, readSimulationHistory);
   const [editingRateId, setEditingRateId] = useState("");
   const [multiplierDraft, setMultiplierDraft] = useState(null);
   const [costDraft, setCostDraft] = useState(null);
@@ -196,10 +197,6 @@ export function RngSimulatorModule({ toolboxId, moduleId, context, editing = fal
   const averageExceededDraws = Math.max(0, Math.round(averageDrawsDelta));
   const averageDrawsTone = realDrawsSummary?.averageExceeded ? (averageExceededDraws > 0 ? "negative" : "") : "positive";
 
-  useEffect(() => {
-    setHistory(readSimulationHistory(historyStorageKey));
-  }, [historyStorageKey]);
-
   useEffect(() => {
     const wasEditing = previousEditingRef.current;
     if (wasEditing && !editing) setEditingRateId("");
diff --git a/website/src/hooks/useKeyedState.js b/website/src/hooks/useKeyedState.js
new file mode 100644
index 0000000..bb02142
--- /dev/null
+++ b/website/src/hooks/useKeyedState.js
@@ -0,0 +1,21 @@
+// Rôle : initialise un état local par clé et ignore les setters d'une identité remplacée.
+import { useCallback, useState } from "react";
+
+export function useKeyedState(key, initialize) {
+  const [state, setState] = useState(() => ({ key, value: initialize(key) }));
+  let current = state;
+  if (!Object.is(state.key, key)) {
+    current = { key, value: initialize(key) };
+    setState(current);
+  }
+
+  const setValue = useCallback((value) => {
+    setState((previous) => {
+      if (!Object.is(previous.key, key)) return previous;
+      const next = typeof value === "function" ? value(previous.value) : value;
+      return Object.is(previous.value, next) ? previous : { key, value: next };
+    });
+  }, [key]);
+
+  return [current.value, setValue];
+}