diff --git a/.beads/interactions.jsonl b/.beads/interactions.jsonl
index c4b3204..f9982b1 100644
--- a/.beads/interactions.jsonl
+++ b/.beads/interactions.jsonl
@@ -24,3 +24,5 @@
 {"id":"int-7ec422ecc24735e12910a965567f32fe","kind":"field_change","created_at":"2026-09-10T12:17:38.573656548Z","actor":"Shinuwa","issue_id":"sokko-g-531","extra":{"field":"status","new_value":"closed","old_value":"in_progress","reason":"Concurrent image batches merge current data after compression; calendar selection handlers update drafts outside state updaters. Behavioral image test and reverse week/month selection E2E pass; npm run check passes."}}
 {"id":"int-1668982a1dda5d8304440ae699a32d40","kind":"field_change","created_at":"2026-09-10T12:22:11.969660039Z","actor":"Shinuwa","issue_id":"sokko-g-5u5","extra":{"field":"status","new_value":"closed","old_value":"in_progress","reason":"Recursive cache enabled for completed evaluations. Before: 131054 reads for 16 cells; after: 50 reads for 50 cells. Regression test failed before fix and passes after; npm run check and table persistence E2E pass."}}
 {"id":"int-903a25fde459880bbbadc2764da920a2","kind":"field_change","created_at":"2026-09-10T16:58:56.754421196Z","actor":"Shinuwa","issue_id":"sokko-g-hf6","extra":{"field":"status","new_value":"closed","old_value":"in_progress","reason":"Unified confirmed-state queue for all writes; imports use current-state updaters; atomic creation/link/deletion and synchronous transaction abort. Removed obsolete checkpoints. Deterministic concurrency/failure tests and real IndexedDB abort E2E pass; full suite 15/15 and npm run check pass."}}
+{"id":"int-16ba759581961e395e133df1c6019895","kind":"field_change","created_at":"2026-09-10T17:21:13.173981957Z","actor":"Shinuwa","issue_id":"sokko-g-ra9","extra":{"field":"status","new_value":"closed","old_value":"in_progress","reason":"Implemented quota coalescing and shared helpers. npm run check and all 15 E2E tests with --workers=2 pass; default concurrency timeouts tracked separately."}}
+{"id":"int-df984435537f78d51a7a309feda1109c","kind":"field_change","created_at":"2026-09-10T17:21:18.79044889Z","actor":"Shinuwa","issue_id":"sokko-g-ckq","extra":{"field":"status","new_value":"closed","old_value":"in_progress","reason":"Implemented quota coalescing and shared helpers. npm run check and all 15 E2E tests with --workers=2 pass; default concurrency timeouts tracked separately."}}
diff --git a/README.md b/README.md
index dfdaa27..f2cd7ea 100644
--- a/README.md
+++ b/README.md
@@ -35,7 +35,9 @@ Le build est généré dans `website/dist`.
 
 ## Configuration
 
-Le serveur lit automatiquement un fichier `.env` à la racine du projet.
+Le serveur et Vite lisent automatiquement un fichier `.env` facultatif à la racine
+du projet, avec le parseur natif de Node. Les variables déjà définies dans le
+processus sont prioritaires, y compris lorsqu'elles sont vides.
 
 ```bash
 cp .env.example .env
diff --git a/docs/STORAGE_SCHEMA.md b/docs/STORAGE_SCHEMA.md
index b5d64f7..86524e9 100644
--- a/docs/STORAGE_SCHEMA.md
+++ b/docs/STORAGE_SCHEMA.md
@@ -52,6 +52,12 @@ sur sa clé et ne réécrivent pas les images des autres outils.
 Cette coordination est locale à l'instance React ; elle ne synchronise pas
 l'édition entre plusieurs onglets.
 
+Les estimations de quota demandées après sauvegarde sont regroupées sur une
+fenêtre de 250 ms, avec une seule estimation active. Une écriture intervenant
+pendant le calcul déclenche une nouvelle estimation. Les sauvegardes ne sont
+pas retardées ; en cas d'estimation indisponible, le dernier quota connu est
+conservé.
+
 Les toolboxes sont stockées dans `kv/toolboxes`.
 
 ```json
diff --git a/scripts/load-project-env.mjs b/scripts/load-project-env.mjs
new file mode 100644
index 0000000..e6e2d12
--- /dev/null
+++ b/scripts/load-project-env.mjs
@@ -0,0 +1,10 @@
+// Rôle : charge le fichier .env facultatif avec le parseur natif de Node.
+import { loadEnvFile } from "node:process";
+
+export function loadProjectEnv(file = ".env") {
+  try {
+    loadEnvFile(file);
+  } catch (error) {
+    if (error.code !== "ENOENT") throw error;
+  }
+}
diff --git a/server.mjs b/server.mjs
index 4ce822f..001525b 100644
--- a/server.mjs
+++ b/server.mjs
@@ -1,5 +1,6 @@
 // Rôle : sert l'application Vite construite ou les sources publiques en local.
-import { createReadStream, existsSync, readFileSync, statSync } from "node:fs";
+import { createReadStream, existsSync, statSync } from "node:fs";
+import { loadProjectEnv } from "./scripts/load-project-env.mjs";
 import { createServer } from "node:http";
 import { extname, join, relative, resolve } from "node:path";
 import { fileURLToPath } from "node:url";
@@ -10,24 +11,7 @@ const distRoot = join(websiteRoot, "dist");
 const root = existsSync(distRoot) ? distRoot : websiteRoot;
 const publicRoot = existsSync(distRoot) ? distRoot : join(websiteRoot, "public");
 
-function loadEnvFile(file = ".env") {
-  if (!existsSync(file)) return;
-
-  const lines = readFileSync(file, "utf8").split(/\r?\n/);
-  lines.forEach((line) => {
-    const trimmed = line.trim();
-    if (!trimmed || trimmed.startsWith("#")) return;
-
-    const separatorIndex = trimmed.indexOf("=");
-    if (separatorIndex < 1) return;
-
-    const key = trimmed.slice(0, separatorIndex).trim();
-    const value = trimmed.slice(separatorIndex + 1).trim().replace(/^["']|["']$/g, "");
-    if (!process.env[key]) process.env[key] = value;
-  });
-}
-
-loadEnvFile();
+loadProjectEnv();
 
 const port = Number(process.env.PORT || 5173);
 
diff --git a/tests/fixtures/project-env.txt b/tests/fixtures/project-env.txt
new file mode 100644
index 0000000..f1e7da9
--- /dev/null
+++ b/tests/fixtures/project-env.txt
@@ -0,0 +1,4 @@
+# Rôle : fournit des variables non sensibles pour tester le chargement .env.
+SOKKOG_ENV_FIXTURE_PORT=4321
+SOKKOG_ENV_FIXTURE_QUOTED="value # inside"
+SOKKOG_ENV_FIXTURE_COMMENT=value # outside
diff --git a/tests/project-env.test.mjs b/tests/project-env.test.mjs
new file mode 100644
index 0000000..3fef838
--- /dev/null
+++ b/tests/project-env.test.mjs
@@ -0,0 +1,20 @@
+// Rôle : vérifie le parsing .env, la priorité du processus et les fichiers facultatifs.
+import { test } from "node:test";
+import assert from "node:assert/strict";
+import { loadProjectEnv } from "../scripts/load-project-env.mjs";
+
+for (const existing of ["9999", ""]) {
+  test(`project env preserves an existing ${existing ? "nonempty" : "empty"} value`, (t) => {
+    const keys = ["SOKKOG_ENV_FIXTURE_PORT", "SOKKOG_ENV_FIXTURE_QUOTED", "SOKKOG_ENV_FIXTURE_COMMENT"];
+    const previous = keys.map((key) => process.env[key]);
+    t.after(() => keys.forEach((key, index) => {
+      if (previous[index] === undefined) delete process.env[key];
+      else process.env[key] = previous[index];
+    }));
+    keys.forEach((key) => { delete process.env[key]; });
+    process.env.SOKKOG_ENV_FIXTURE_PORT = existing;
+    loadProjectEnv("tests/fixtures/project-env.txt");
+    loadProjectEnv("tests/fixtures/missing-env-file");
+    assert.deepEqual(keys.map((key) => process.env[key]), [existing, "value # inside", "value"]);
+  });
+}
diff --git a/tests/quota-refresh.test.mjs b/tests/quota-refresh.test.mjs
new file mode 100644
index 0000000..80c085e
--- /dev/null
+++ b/tests/quota-refresh.test.mjs
@@ -0,0 +1,90 @@
+// Rôle : teste les rafales d'estimations, la concurrence et le nettoyage du quota.
+import { test } from "node:test";
+import assert from "node:assert/strict";
+import { createQuotaRefresh } from "../website/src/features/toolboxes/storage/quotaRefresh.js";
+
+function setup(estimate) {
+  const timers = new Map();
+  const results = [];
+  let id = 0;
+  const refresh = createQuotaRefresh({
+    estimate,
+    onResult: (result) => results.push(result),
+    schedule: (callback) => { timers.set(++id, callback); return id; },
+    cancel: (key) => timers.delete(key)
+  });
+  function tick() {
+    assert.equal(timers.size, 1);
+    const [key, callback] = timers.entries().next().value;
+    timers.delete(key);
+    return callback();
+  }
+  return { ...refresh, timers, results, tick };
+}
+
+test("one hundred refresh requests trigger one estimate", async () => {
+  let calls = 0;
+  const refresh = setup(async () => { calls++; return { usage: 12 }; });
+  for (let i = 0; i < 100; i++) refresh.request();
+  await refresh.tick();
+  assert.equal(calls, 1);
+  assert.deepEqual(refresh.results, [{ usage: 12 }]);
+  assert.equal(refresh.timers.size, 0);
+});
+
+test("writes during estimation schedule one follow-up and discard the stale result", async () => {
+  let finish;
+  let calls = 0;
+  const refresh = setup(() => {
+    calls++;
+    return new Promise((resolve) => { finish = resolve; });
+  });
+  refresh.request();
+  const first = refresh.tick();
+  for (let i = 0; i < 100; i++) refresh.request();
+  assert.equal(calls, 1);
+  assert.equal(refresh.timers.size, 0);
+  finish({ usage: 1 });
+  await first;
+  assert.deepEqual(refresh.results, []);
+  const second = refresh.tick();
+  finish({ usage: 2 });
+  await second;
+  assert.equal(calls, 2);
+  assert.deepEqual(refresh.results, [{ usage: 2 }]);
+});
+
+test("dispose cancels scheduled work and ignores in-flight results", async () => {
+  let finish;
+  const refresh = setup(() => new Promise((resolve) => { finish = resolve; }));
+  refresh.request();
+  refresh.dispose();
+  refresh.request();
+  assert.equal(refresh.timers.size, 0);
+  const active = setup(() => new Promise((resolve) => { finish = resolve; }));
+  active.request();
+  const task = active.tick();
+  active.dispose();
+  finish({ usage: 5 });
+  await task;
+  assert.deepEqual(active.results, []);
+  assert.equal(active.timers.size, 0);
+});
+
+test("a failed estimate preserves the last result and allows recovery", async () => {
+  let fail = false;
+  const refresh = setup(async () => {
+    if (fail) throw new Error("unavailable");
+    return { usage: 3 };
+  });
+  refresh.request();
+  await refresh.tick();
+  fail = true;
+  refresh.request();
+  await refresh.tick();
+  assert.deepEqual(refresh.results, [{ usage: 3 }]);
+  fail = false;
+  refresh.request();
+  await refresh.tick();
+  assert.equal(refresh.results.length, 2);
+});
diff --git a/tests/static-app.test.mjs b/tests/static-app.test.mjs
index 346af9f..f7bafbb 100644
--- a/tests/static-app.test.mjs
+++ b/tests/static-app.test.mjs
@@ -113,9 +113,9 @@ test("server and vite support local env configuration", async () => {
   const viteConfig = await readFile("vite.config.js", "utf8");
   const envExample = await readFile(".env.example", "utf8");
 
-  assert.match(server, /function loadEnvFile/);
+  assert.match(server, /load-project-env\.mjs/);
   assert.match(server, /process\.env\.PORT/);
-  assert.match(viteConfig, /function loadEnvFile/);
+  assert.match(viteConfig, /load-project-env\.mjs/);
   assert.match(viteConfig, /process\.env\.PORT/);
   assert.match(envExample, /PORT=5173/);
 });
diff --git a/vite.config.js b/vite.config.js
index c850759..74a61c9 100644
--- a/vite.config.js
+++ b/vite.config.js
@@ -1,24 +1,9 @@
+// Rôle : configure Vite et charge les variables locales communes au serveur.
 import { defineConfig } from "vite";
 import react from "@vitejs/plugin-react";
-import { existsSync, readFileSync } from "node:fs";
+import { loadProjectEnv } from "./scripts/load-project-env.mjs";
 
-function loadEnvFile(file = ".env") {
-  if (!existsSync(file)) return;
-
-  readFileSync(file, "utf8").split(/\r?\n/).forEach((line) => {
-    const trimmed = line.trim();
-    if (!trimmed || trimmed.startsWith("#")) return;
-
-    const separatorIndex = trimmed.indexOf("=");
-    if (separatorIndex < 1) return;
-
-    const key = trimmed.slice(0, separatorIndex).trim();
-    const value = trimmed.slice(separatorIndex + 1).trim().replace(/^["']|["']$/g, "");
-    if (!process.env[key]) process.env[key] = value;
-  });
-}
-
-loadEnvFile();
+loadProjectEnv();
 
 export default defineConfig({
   root: "website",
diff --git a/website/src/components/ImageViewer.jsx b/website/src/components/ImageViewer.jsx
index 30167d9..5b33b84 100644
--- a/website/src/components/ImageViewer.jsx
+++ b/website/src/components/ImageViewer.jsx
@@ -3,12 +3,10 @@ import { useEffect, useRef, useState } from "react";
 import { DrawingControls } from "../features/toolboxes/modules/DrawingControls.jsx";
 import { DrawingOverlay } from "../features/toolboxes/modules/DrawingOverlay.jsx";
 import { lockBodyScroll } from "../utils/bodyScrollLock.js";
+import { DRAWING_COLORS, DRAWING_WIDTHS } from "../utils/drawingOptions.js";
 import { Icon } from "./Icon.jsx";
 import { Tooltip } from "./Tooltip.jsx";
 
-const DRAWING_COLORS = ["#f5f7ff", "#b4bdd3", "#f6c453", "#22d3ee", "#8b5cf6", "#d946ef"];
-const DRAWING_WIDTHS = [2, 4, 8, 12];
-
 function clampPercent(value) {
   const parsed = Number(value);
   if (!Number.isFinite(parsed)) return 0;
diff --git a/website/src/features/toolboxes/modules/CombosModule.jsx b/website/src/features/toolboxes/modules/CombosModule.jsx
index 008e381..774b2b1 100644
--- a/website/src/features/toolboxes/modules/CombosModule.jsx
+++ b/website/src/features/toolboxes/modules/CombosModule.jsx
@@ -1,4 +1,5 @@
 // Rôle : fournit l'outil Combos avec palettes d'inputs, rendu visuel et échange texte.
+import { toggleListValue } from "../../../utils/collectionUtils.js";
 import { getGroupedEntries } from "../../../hooks/useGroupedReorder.js";
 import { TextExchangeActions } from "./TextExchangeActions.jsx";
 import { CombosEditor } from "./CombosEditor.jsx";
@@ -40,9 +41,7 @@ export function CombosModule({ toolboxId, moduleId, context, editing, textExchan
   }
 
   function toggleCategoryCollapsed(category) {
-    const collapsedCategories = data.collapsedCategories.includes(category)
-      ? data.collapsedCategories.filter((item) => item !== category)
-      : [...data.collapsedCategories, category];
+    const collapsedCategories = toggleListValue(data.collapsedCategories, category);
     save({ ...data, collapsedCategories });
   }
 
diff --git a/website/src/features/toolboxes/modules/LinksModule.jsx b/website/src/features/toolboxes/modules/LinksModule.jsx
index 7a69ebe..edffa7b 100644
--- a/website/src/features/toolboxes/modules/LinksModule.jsx
+++ b/website/src/features/toolboxes/modules/LinksModule.jsx
@@ -1,4 +1,5 @@
 // Rôle : fournit l'outil liens avec ajout manuel et échange texte.
+import { toggleListValue } from "../../../utils/collectionUtils.js";
 import { useState } from "react";
 import { CategoryAutocompleteInput } from "../../../components/CategoryAutocompleteInput.jsx";
 import { Icon } from "../../../components/Icon.jsx";
@@ -143,9 +144,7 @@ export function LinksModule({ toolboxId, moduleId, context, editing, textExchang
   }
 
   function toggleCategoryCollapsed(category) {
-    const collapsedCategories = data.collapsedCategories.includes(category)
-      ? data.collapsedCategories.filter((item) => item !== category)
-      : [...data.collapsedCategories, category];
+    const collapsedCategories = toggleListValue(data.collapsedCategories, category);
     save({ ...data, collapsedCategories });
   }
 
diff --git a/website/src/features/toolboxes/modules/TaskPlannerModule.jsx b/website/src/features/toolboxes/modules/TaskPlannerModule.jsx
index 8016f6e..6444499 100644
--- a/website/src/features/toolboxes/modules/TaskPlannerModule.jsx
+++ b/website/src/features/toolboxes/modules/TaskPlannerModule.jsx
@@ -1,4 +1,5 @@
 // Rôle : fournit l'outil task planner avec tâches récurrentes, parents, pré requis et échange texte.
+import { toggleListValue } from "../../../utils/collectionUtils.js";
 import { useEffect, useMemo, useRef, useState } from "react";
 import { useDraftForm } from "../../../hooks/useDraftForm.js";
 import { TaskPlannerBranch } from "./TaskPlannerBranch.jsx";
@@ -131,9 +132,7 @@ export function TaskPlannerModule({ toolboxId, moduleId, context, editing, textE
   }
 
   function toggleCategoryCollapsed(category) {
-    const collapsedCategories = data.collapsedCategories.includes(category)
-      ? data.collapsedCategories.filter((item) => item !== category)
-      : [...data.collapsedCategories, category];
+    const collapsedCategories = toggleListValue(data.collapsedCategories, category);
     save({ ...data, collapsedCategories });
   }
 
diff --git a/website/src/features/toolboxes/modules/notepadUtils.js b/website/src/features/toolboxes/modules/notepadUtils.js
index 3cf103f..6143afb 100644
--- a/website/src/features/toolboxes/modules/notepadUtils.js
+++ b/website/src/features/toolboxes/modules/notepadUtils.js
@@ -1,7 +1,6 @@
 // Rôle : regroupe les constantes et helpers DOM du Bloc Note riche.
-export const TEXT_COLORS = ["#f5f7ff", "#b4bdd3", "#f6c453", "#22d3ee", "#8b5cf6", "#d946ef"];
+export { DRAWING_COLORS as TEXT_COLORS, DRAWING_WIDTHS } from "../../../utils/drawingOptions.js";
 export const HIGHLIGHT_COLORS = ["#f6c453", "#22d3ee", "#8b5cf6", "#d946ef", "#202745"];
-export const DRAWING_WIDTHS = [2, 4, 8, 12];
 
 export function getPlainText(element) {
   return (element?.innerText || "").replace(/\n{3,}/g, "\n\n").trim();
diff --git a/website/src/features/toolboxes/storage/quotaRefresh.js b/website/src/features/toolboxes/storage/quotaRefresh.js
new file mode 100644
index 0000000..2808043
--- /dev/null
+++ b/website/src/features/toolboxes/storage/quotaRefresh.js
@@ -0,0 +1,38 @@
+// Rôle : regroupe les estimations de quota et ignore les résultats devenus obsolètes.
+export function createQuotaRefresh({ estimate, onResult, delay = 250, schedule = setTimeout, cancel = clearTimeout }) {
+  let timer = null;
+  let running = false;
+  let dirty = false;
+  let disposed = false;
+
+  function request() {
+    if (disposed) return;
+    dirty = true;
+    if (!running && timer === null) timer = schedule(run, delay);
+  }
+
+  async function run() {
+    timer = null;
+    if (disposed) return;
+    dirty = false;
+    running = true;
+    try {
+      const result = await estimate();
+      if (!disposed && !dirty) onResult(result);
+    } catch {
+      // Une estimation indisponible ne remet pas à zéro le dernier quota connu.
+    } finally {
+      running = false;
+      if (!disposed && dirty) request();
+    }
+  }
+
+  return {
+    request,
+    dispose() {
+      disposed = true;
+      if (timer !== null) cancel(timer);
+      timer = null;
+    }
+  };
+}
diff --git a/website/src/features/toolboxes/storage/useIndexedToolboxes.js b/website/src/features/toolboxes/storage/useIndexedToolboxes.js
index 05594a5..f723188 100644
--- a/website/src/features/toolboxes/storage/useIndexedToolboxes.js
+++ b/website/src/features/toolboxes/storage/useIndexedToolboxes.js
@@ -1,5 +1,5 @@
 // Rôle : synchronise l'état optimiste des toolboxes avec une file d'écritures IndexedDB.
-import { useCallback, useEffect, useState } from "react";
+import { useCallback, useEffect, useRef, useState } from "react";
 import {
   getAllModuleData as dbGetAllModuleData,
   getLinks as dbGetLinks,
@@ -22,6 +22,7 @@ import {
 } from "./toolboxStorage.js";
 import { applyModuleDataValue, removeModuleDataKeys } from "./optimisticModuleData.js";
 import { createPersistenceQueue } from "./persistenceQueue.js";
+import { createQuotaRefresh } from "./quotaRefresh.js";
 
 function normalizeToolboxes(toolboxes) {
   return compactToolboxesForStorage(toolboxes).map(normalizeToolbox).filter(Boolean);
@@ -32,20 +33,29 @@ export function useIndexedToolboxes(onError) {
   const [state, setState] = useState({ toolboxes: [], links: {}, moduleData: {}, toastPosition: "right" });
   const [queue] = useState(() => createPersistenceQueue(state, setState));
   const [storageUsage, setStorageUsage] = useState({ used: 0, limit: 0, ratio: 0 });
+  const quotaRefreshRef = useRef(null);
   const reportStorageError = useCallback((error) => {
     onError(error?.message || "Erreur de stockage IndexedDB.");
   }, [onError]);
 
-  const refreshQuota = useCallback(async () => {
-    try {
-      const estimate = await getStorageEstimate();
-      const used = estimate.usage || 0;
-      const limit = estimate.quota || 0;
-      setStorageUsage({ used, limit, ratio: limit ? Math.min(1, used / limit) : 0 });
-    } catch {
-      setStorageUsage({ used: 0, limit: 0, ratio: 0 });
-    }
+  useEffect(() => {
+    const refresh = createQuotaRefresh({
+      estimate: getStorageEstimate,
+      onResult: (estimate) => {
+        const used = estimate.usage || 0;
+        const limit = estimate.quota || 0;
+        setStorageUsage((current) => current.used === used && current.limit === limit
+          ? current
+          : { used, limit, ratio: limit ? Math.min(1, used / limit) : 0 });
+      }
+    });
+    quotaRefreshRef.current = refresh;
+    return () => {
+      refresh.dispose();
+      quotaRefreshRef.current = null;
+    };
   }, []);
+  const refreshQuota = useCallback(() => quotaRefreshRef.current?.request(), []);
 
   useEffect(() => {
     let cancelled = false;
diff --git a/website/src/utils/collectionUtils.js b/website/src/utils/collectionUtils.js
new file mode 100644
index 0000000..b536afc
--- /dev/null
+++ b/website/src/utils/collectionUtils.js
@@ -0,0 +1,4 @@
+// Rôle : fournit les modifications immuables communes aux listes de valeurs.
+export function toggleListValue(values, value) {
+  return values.includes(value) ? values.filter((item) => item !== value) : [...values, value];
+}
diff --git a/website/src/utils/drawingOptions.js b/website/src/utils/drawingOptions.js
new file mode 100644
index 0000000..31961b6
--- /dev/null
+++ b/website/src/utils/drawingOptions.js
@@ -0,0 +1,3 @@
+// Rôle : partage les couleurs et épaisseurs des outils de dessin.
+export const DRAWING_COLORS = ["#f5f7ff", "#b4bdd3", "#f6c453", "#22d3ee", "#8b5cf6", "#d946ef"];
+export const DRAWING_WIDTHS = [2, 4, 8, 12];