diff --git a/apps/web/src/lib/api.ts b/apps/web/src/lib/api.ts
index d064ecf..779ffd9 100644
--- a/apps/web/src/lib/api.ts
+++ b/apps/web/src/lib/api.ts
@@ -231,4 +231,45 @@ export const api = {
     const blob = await res.blob();
     return { blob, contentType: res.headers.get("content-type") ?? blob.type };
   },
+
+  /**
+   * POST avec body JSON et réponse binaire. Pendant inverse de `fetchBlob`,
+   * utilisé pour la preview PDF (POST /invoices/preview-pdf renvoie un PDF).
+   *
+   * Mêmes contraintes que fetchBlob : pas de silent refresh sur 401 (le
+   * caller debounced retry de toute façon à chaque keystroke). Le body est
+   * JSON-encoded ; pas de support FormData ici (cas spécifique aux preview).
+   */
+  postBlob: async (
+    path: string,
+    body: unknown,
+    signal?: AbortSignal,
+  ): Promise<Blob> => {
+    const url = path.startsWith("http") ? path : `${env.VITE_API_URL}${path}`;
+    const res = await fetch(url, {
+      method: "POST",
+      headers: {
+        "Content-Type": "application/json",
+        Accept: "application/pdf,application/octet-stream",
+        ...(authStore.token ? { Authorization: `Bearer ${authStore.token}` } : {}),
+      },
+      credentials: "include",
+      body: JSON.stringify(body),
+      signal,
+    });
+    if (!res.ok) {
+      // Le serveur peut renvoyer du JSON `{errors: [...]}` même sur un POST
+      // qui attendait un Blob — on tente de parser pour donner un message utile.
+      const text = await res.text().catch(() => null);
+      let message = `HTTP ${res.status} on ${path}`;
+      try {
+        const json = text ? JSON.parse(text) : null;
+        if (json?.errors?.[0]?.message) message = json.errors[0].message;
+      } catch {
+        // text non-JSON → on garde le message générique
+      }
+      throw new ApiError(res.status, "blob_post_failed", message);
+    }
+    return res.blob();
+  },
 };
diff --git a/apps/web/src/lib/invoices.ts b/apps/web/src/lib/invoices.ts
index d26ddf8..c530de9 100644
--- a/apps/web/src/lib/invoices.ts
+++ b/apps/web/src/lib/invoices.ts
@@ -1,3 +1,6 @@
+import { useMutation, useQueryClient } from "@tanstack/react-query";
+import type { CreateNativeInvoiceInput, Invoice, PreviewInvoiceInput } from "@rubis/shared";
+
 import { api } from "@/lib/api";
 
 export type ImportBatchResponse = {
@@ -12,3 +15,38 @@ export function uploadInvoiceFiles(files: File[]): Promise<ImportBatchResponse>
   }
   return api.post<ImportBatchResponse>("/api/v1/invoices/upload", formData);
 }
+
+/**
+ * POST /invoices/native — création depuis l'éditeur natif.
+ *
+ *  - Pas de `numero` : alloué côté serveur (séquence strict)
+ *  - Pas de `amountTtcCents` : recalculé depuis lines
+ *  - `draft: true` → la facture est créée mais ne consomme pas la séquence
+ *    (numero éphémère "BROUILLON-XXX")
+ */
+export function useCreateNativeInvoice() {
+  const qc = useQueryClient();
+  return useMutation({
+    mutationFn: (input: CreateNativeInvoiceInput) =>
+      api.post<Invoice>("/api/v1/invoices/native", input),
+    onSuccess: () => {
+      // Toute la liste / counts deviennent obsolètes.
+      qc.invalidateQueries({ queryKey: ["invoices"] });
+      qc.invalidateQueries({ queryKey: ["invoice-counts"] });
+    },
+  });
+}
+
+/**
+ * POST /invoices/preview-pdf — stream un PDF sans persister.
+ *
+ * Retourne un Blob à transformer en objectURL côté composant pour l'afficher
+ * dans un <iframe>. À débouncer côté caller (500ms typique) pour ne pas
+ * spammer le serveur pendant la saisie.
+ */
+export async function previewInvoicePdf(
+  input: PreviewInvoiceInput,
+  signal?: AbortSignal,
+): Promise<Blob> {
+  return api.postBlob("/api/v1/invoices/preview-pdf", input, signal);
+}
diff --git a/apps/web/src/routes/_app/factures.tsx b/apps/web/src/routes/_app/factures.tsx
index 98e6446..bb26c95 100644
--- a/apps/web/src/routes/_app/factures.tsx
+++ b/apps/web/src/routes/_app/factures.tsx
@@ -188,13 +188,21 @@ function FacturesPage() {
             pour voir la timeline.
           </p>
         </div>
-        <Button size="sm" asChild className="shrink-0">
-          <Link to="/factures/import">
-            <Plus size={14} aria-hidden="true" />
-            <span className="hidden sm:inline">Nouvelle facture</span>
-            <span className="sm:hidden">Nouvelle</span>
-          </Link>
-        </Button>
+        <div className="flex shrink-0 items-center gap-2">
+          <Button size="sm" variant="secondary" asChild>
+            <Link to="/factures/import">
+              <span className="hidden sm:inline">Importer</span>
+              <span className="sm:hidden">Import</span>
+            </Link>
+          </Button>
+          <Button size="sm" asChild>
+            <Link to="/factures/nouvelle">
+              <Plus size={14} aria-hidden="true" />
+              <span className="hidden sm:inline">Créer une facture</span>
+              <span className="sm:hidden">Créer</span>
+            </Link>
+          </Button>
+        </div>
       </div>
 
       <PlanLimitBanner />
diff --git a/apps/web/src/routes/_app/factures_.nouvelle.tsx b/apps/web/src/routes/_app/factures_.nouvelle.tsx
new file mode 100644
index 0000000..a78e50c
--- /dev/null
+++ b/apps/web/src/routes/_app/factures_.nouvelle.tsx
@@ -0,0 +1,599 @@
+import { useEffect, useMemo, useRef, useState } from "react";
+import { createFileRoute, Link, useNavigate } from "@tanstack/react-router";
+import { useQuery } from "@tanstack/react-query";
+import { addDays } from "date-fns";
+import {
+  ArrowLeft,
+  Check,
+  GripVertical,
+  Loader2,
+  Plus,
+  Save,
+  Send,
+  Trash2,
+} from "lucide-react";
+import type {
+  CreateNativeInvoiceInput,
+  InvoiceLineInput,
+  InvoiceThemeSlug,
+  Plan,
+} from "@rubis/shared";
+import { FRENCH_TVA_RATES } from "@rubis/shared";
+
+import { api } from "@/lib/api";
+import { useInvoiceSettings, useInvoiceThemes } from "@/lib/invoice-settings";
+import { previewInvoicePdf, useCreateNativeInvoice } from "@/lib/invoices";
+import { ApiError } from "@/lib/api";
+import { Button, Card, Eyebrow } from "@rubis/ui";
+import { Input } from "@/components/ui/Input";
+import { Textarea } from "@/components/ui/Textarea";
+import { Field } from "@/components/ui/Field";
+import { ClientCombobox } from "@/components/factures/ClientCombobox";
+import { cn } from "@/lib/utils";
+
+export const Route = createFileRoute("/_app/factures_/nouvelle")({
+  component: FacturesNouvellePage,
+});
+
+const newLine = (): InvoiceLineInput => ({
+  id: crypto.randomUUID(),
+  description: "",
+  quantity: 1,
+  unitPriceCents: 0,
+  tvaRate: 20,
+});
+
+function FacturesNouvellePage() {
+  const navigate = useNavigate();
+  const { data: settings } = useInvoiceSettings();
+  const { data: themes } = useInvoiceThemes();
+  const { data: plans } = useQuery({
+    queryKey: ["plans"],
+    queryFn: () => api.get<Plan[]>("/api/v1/plans"),
+  });
+
+  // ============== Form state ==============
+  const [clientName, setClientName] = useState("");
+  const [clientId, setClientId] = useState<string | null>(null);
+
+  const todayIso = useMemo(() => new Date().toISOString().slice(0, 10), []);
+  const [issueDate, setIssueDate] = useState(todayIso);
+  const [paymentTermsDays, setPaymentTermsDays] = useState(30);
+
+  const [planId, setPlanId] = useState<string | null>(null);
+  const [themeSlug, setThemeSlug] = useState<InvoiceThemeSlug>("classique");
+  const [accentColor, setAccentColor] = useState("#9F1239");
+
+  const [lines, setLines] = useState<InvoiceLineInput[]>([newLine()]);
+  const [footerNotes, setFooterNotes] = useState("");
+
+  // Initialize defaults from invoice-settings (one-shot, après load).
+  const settingsInitDone = useRef(false);
+  useEffect(() => {
+    if (settings?.resolved && !settingsInitDone.current) {
+      setThemeSlug(settings.resolved.themeSlug);
+      setAccentColor(settings.resolved.accentColor);
+      setPaymentTermsDays(settings.resolved.paymentTermsDays);
+      settingsInitDone.current = true;
+    }
+  }, [settings]);
+
+  const dueDateIso = useMemo(
+    () => addDays(new Date(issueDate), paymentTermsDays).toISOString().slice(0, 10),
+    [issueDate, paymentTermsDays],
+  );
+
+  // ============== Totals (côté client pour feedback instantané) ==============
+  const totals = useMemo(() => computeTotals(lines), [lines]);
+
+  // ============== Preview PDF debounced ==============
+  const { previewUrl, previewError, isRefreshing } = usePreview({
+    clientId,
+    issueDate,
+    paymentTermsDays,
+    themeSlug,
+    accentColor,
+    lines,
+    footerNotes,
+  });
+
+  // ============== Submit ==============
+  const create = useCreateNativeInvoice();
+  const [submitError, setSubmitError] = useState<string | null>(null);
+
+  const onSubmit = async (draft: boolean) => {
+    if (!clientId) {
+      setSubmitError("Sélectionnez un client.");
+      return;
+    }
+    setSubmitError(null);
+    const payload: CreateNativeInvoiceInput = {
+      clientId,
+      issueDate: new Date(issueDate).toISOString(),
+      dueDate: new Date(dueDateIso).toISOString(),
+      paymentTermsDays,
+      planId: planId ?? undefined,
+      themeSlug,
+      accentColor,
+      lines,
+      footerNotes: footerNotes.trim() === "" ? null : footerNotes,
+      draft,
+    };
+    try {
+      const invoice = await create.mutateAsync(payload);
+      navigate({ to: "/factures/$id", params: { id: invoice.id } });
+    } catch (err) {
+      setSubmitError(err instanceof Error ? err.message : "Erreur inconnue");
+    }
+  };
+
+  const canSubmit =
+    !!clientId &&
+    lines.length > 0 &&
+    lines.every((l) => l.description.trim() !== "" && l.unitPriceCents >= 0);
+
+  return (
+    <div className="flex flex-col gap-4">
+      <header>
+        <Button size="sm" variant="ghost" asChild className="mb-3 -ml-2">
+          <Link to="/factures">
+            <ArrowLeft size={14} aria-hidden="true" /> Retour aux factures
+          </Link>
+        </Button>
+        <h1 className="font-display text-[26px] font-bold tracking-[-0.022em] text-ink">
+          Nouvelle facture
+        </h1>
+        <p className="mt-1 text-[13.5px] text-ink-3">
+          Composez votre facture, l'aperçu se rafraîchit automatiquement.
+          L'émission alloue le prochain numéro de la séquence ; le brouillon
+          conserve un numéro éphémère.
+        </p>
+      </header>
+
+      <div className="grid gap-4 lg:grid-cols-[minmax(0,1fr)_minmax(0,1fr)]">
+        {/* ========== Édition ========== */}
+        <div className="flex flex-col gap-4">
+          <Card padding="md" className="flex flex-col gap-4">
+            <Eyebrow>Destinataire</Eyebrow>
+            <Field label="Client" hint="Recherchez ou créez à la volée">
+              <ClientCombobox
+                value={clientName}
+                selectedClientId={clientId}
+                onChange={({ value, clientId }) => {
+                  setClientName(value);
+                  setClientId(clientId);
+                }}
+              />
+            </Field>
+          </Card>
+
+          <Card padding="md" className="flex flex-col gap-4">
+            <Eyebrow>Dates & paiement</Eyebrow>
+            <div className="grid gap-4 sm:grid-cols-3">
+              <Field label="Émise le">
+                <Input
+                  type="date"
+                  value={issueDate}
+                  onChange={(e) => setIssueDate(e.target.value)}
+                />
+              </Field>
+              <Field label="Délai" hint="Jours">
+                <Input
+                  type="number"
+                  value={paymentTermsDays}
+                  onChange={(e) =>
+                    setPaymentTermsDays(Number(e.target.value) || 0)
+                  }
+                  min={0}
+                  max={365}
+                />
+              </Field>
+              <Field label="Échéance" hint="Calculée automatiquement">
+                <Input type="date" value={dueDateIso} readOnly className="bg-cream-2" />
+              </Field>
+            </div>
+            <Field
+              label="Plan de relance"
+              hint="Optionnel — si associé, Rubis programmera le check-in puis les relances à l'échéance."
+            >
+              <select
+                value={planId ?? ""}
+                onChange={(e) => setPlanId(e.target.value || null)}
+                className="block w-full rounded-default border border-line bg-white px-3.5 py-3 text-base lg:text-[15px] text-ink"
+              >
+                <option value="">Aucun plan (relances manuelles)</option>
+                {(plans ?? []).map((p) => (
+                  <option key={p.id} value={p.id}>
+                    {p.name}
+                  </option>
+                ))}
+              </select>
+            </Field>
+          </Card>
+
+          <Card padding="md" className="flex flex-col gap-4">
+            <div className="flex items-center justify-between">
+              <Eyebrow>Lignes</Eyebrow>
+              <Button
+                size="sm"
+                variant="ghost"
+                onClick={() => setLines((ls) => [...ls, newLine()])}
+              >
+                <Plus size={14} aria-hidden="true" /> Ajouter une ligne
+              </Button>
+            </div>
+
+            <LinesEditor lines={lines} setLines={setLines} />
+
+            <TotalsBlock totals={totals} />
+          </Card>
+
+          <Card padding="md" className="flex flex-col gap-4">
+            <Eyebrow>Thème & accent</Eyebrow>
+            <div className="grid gap-3 sm:grid-cols-4">
+              {(themes ?? []).map((t) => (
+                <button
+                  key={t.slug}
+                  type="button"
+                  onClick={() => setThemeSlug(t.slug)}
+                  className={cn(
+                    "rounded-default border bg-white px-3 py-2 text-left text-[13px] font-semibold transition-colors",
+                    themeSlug === t.slug
+                      ? "border-rubis ring-4 ring-rubis-glow text-ink"
+                      : "border-line text-ink-2 hover:border-rubis-light",
+                  )}
+                >
+                  <span className="flex items-center justify-between">
+                    {t.name}
+                    {themeSlug === t.slug ? (
+                      <Check size={14} className="text-rubis" aria-hidden="true" />
+                    ) : null}
+                  </span>
+                </button>
+              ))}
+            </div>
+            <Field label="Couleur d'accent" hint="Hex #RRGGBB">
+              <div className="flex items-center gap-3">
+                <input
+                  type="color"
+                  value={accentColor}
+                  onChange={(e) => setAccentColor(e.target.value)}
+                  className="h-11 w-16 cursor-pointer rounded-default border border-line bg-white p-1"
+                  aria-label="Choisir la couleur d'accent"
+                />
+                <Input
+                  value={accentColor}
+                  onChange={(e) => setAccentColor(e.target.value)}
+                  maxLength={7}
+                  className="font-mono lg:max-w-[160px]"
+                />
+              </div>
+            </Field>
+          </Card>
+
+          <Card padding="md">
+            <Eyebrow>Notes</Eyebrow>
+            <Textarea
+              value={footerNotes}
+              onChange={(e) => setFooterNotes(e.target.value)}
+              rows={3}
+              maxLength={1000}
+              placeholder="Notes affichées en pied de facture (références projet, conditions spécifiques…)"
+              className="mt-2"
+            />
+          </Card>
+        </div>
+
+        {/* ========== Preview ========== */}
+        <div className="lg:sticky lg:top-4 lg:self-start">
+          <Card padding="sm" className="flex h-[calc(100vh-160px)] flex-col gap-2">
+            <div className="flex items-center justify-between px-2">
+              <Eyebrow>Aperçu</Eyebrow>
+              {isRefreshing ? (
+                <span className="flex items-center gap-1 text-[11px] text-ink-3">
+                  <Loader2 size={11} className="animate-spin" /> Génération…
+                </span>
+              ) : null}
+            </div>
+            {previewError ? (
+              <div className="flex flex-1 items-center justify-center rounded-default border border-dashed border-line bg-cream-2 p-6 text-center text-[13px] text-ink-3">
+                {previewError}
+              </div>
+            ) : previewUrl ? (
+              <iframe
+                src={previewUrl}
+                title="Aperçu de la facture"
+                className="flex-1 w-full rounded-default border border-line bg-white"
+              />
+            ) : (
+              <div className="flex flex-1 items-center justify-center rounded-default border border-dashed border-line bg-cream-2 p-6 text-center text-[13px] text-ink-3">
+                Sélectionnez un client et au moins une ligne pour générer l'aperçu.
+              </div>
+            )}
+          </Card>
+        </div>
+      </div>
+
+      {/* ========== Footer actions ========== */}
+      <div className="sticky bottom-0 -mx-4 mt-2 border-t border-line bg-cream/95 px-4 py-3 backdrop-blur lg:-mx-6 lg:px-6">
+        <div className="flex items-center justify-end gap-3">
+          {submitError ? (
+            <p className="mr-auto text-[13px] font-medium text-rubis-deep">
+              {submitError}
+            </p>
+          ) : null}
+          <Button
+            variant="secondary"
+            size="md"
+            onClick={() => onSubmit(true)}
+            disabled={!canSubmit || create.isPending}
+          >
+            <Save size={14} aria-hidden="true" /> Enregistrer en brouillon
+          </Button>
+          <Button
+            size="md"
+            onClick={() => onSubmit(false)}
+            disabled={!canSubmit || create.isPending}
+          >
+            <Send size={14} aria-hidden="true" /> Émettre la facture
+          </Button>
+        </div>
+        <p className="mt-2 text-right text-[11.5px] text-ink-3">
+          Émettre = alloue le prochain numéro de la séquence (irréversible).
+          Brouillon = conserve un numéro éphémère, modifiable plus tard.
+        </p>
+      </div>
+    </div>
+  );
+}
+
+// ============================================================================
+// LinesEditor — table éditable avec add/remove (drag-and-drop = V2)
+// ============================================================================
+
+function LinesEditor({
+  lines,
+  setLines,
+}: {
+  lines: InvoiceLineInput[];
+  setLines: (next: InvoiceLineInput[] | ((prev: InvoiceLineInput[]) => InvoiceLineInput[])) => void;
+}) {
+  const update = (id: string, patch: Partial<InvoiceLineInput>) => {
+    setLines((ls) => ls.map((l) => (l.id === id ? { ...l, ...patch } : l)));
+  };
+  const remove = (id: string) => {
+    setLines((ls) => ls.filter((l) => l.id !== id));
+  };
+
+  return (
+    <div className="flex flex-col gap-2">
+      {/* Header */}
+      <div className="hidden grid-cols-[24px_1fr_80px_120px_80px_120px_28px] gap-2 px-2 text-[10.5px] uppercase tracking-[0.08em] text-ink-3 sm:grid">
+        <span aria-hidden="true" />
+        <span>Désignation</span>
+        <span className="text-right">Qté</span>
+        <span className="text-right">P.U. HT</span>
+        <span className="text-right">TVA</span>
+        <span className="text-right">Total HT</span>
+        <span aria-hidden="true" />
+      </div>
+      {lines.map((line) => {
+        const totalHt = Math.round(line.quantity * line.unitPriceCents);
+        return (
+          <div
+            key={line.id}
+            className="grid grid-cols-1 gap-2 rounded-default border border-line bg-white p-2 sm:grid-cols-[24px_1fr_80px_120px_80px_120px_28px] sm:items-center sm:p-1.5"
+          >
+            <span className="hidden text-ink-3 sm:flex sm:justify-center" aria-hidden="true">
+              <GripVertical size={14} />
+            </span>
+            <Input
+              value={line.description}
+              onChange={(e) => update(line.id, { description: e.target.value })}
+              placeholder="Désignation"
+              className="text-[14px]"
+            />
+            <Input
+              type="number"
+              value={line.quantity}
+              onChange={(e) => update(line.id, { quantity: Number(e.target.value) || 0 })}
+              step="0.5"
+              min={0}
+              className="text-right text-[14px]"
+            />
+            <Input
+              type="number"
+              value={(line.unitPriceCents / 100).toFixed(2)}
+              onChange={(e) =>
+                update(line.id, {
+                  unitPriceCents: Math.round((Number(e.target.value) || 0) * 100),
+                })
+              }
+              step="0.01"
+              min={0}
+              className="text-right text-[14px]"
+              placeholder="0,00"
+            />
+            <select
+              value={line.tvaRate}
+              onChange={(e) => update(line.id, { tvaRate: Number(e.target.value) })}
+              className="rounded-default border border-line bg-white px-2 py-2 text-[14px] text-ink"
+            >
+              {FRENCH_TVA_RATES.map((rate) => (
+                <option key={rate} value={rate}>
+                  {Number.isInteger(rate) ? `${rate} %` : `${rate.toString().replace(".", ",")} %`}
+                </option>
+              ))}
+            </select>
+            <div className="text-right font-mono text-[14px] tabular-nums text-ink">
+              {(totalHt / 100).toLocaleString("fr-FR", {
+                style: "currency",
+                currency: "EUR",
+              })}
+            </div>
+            <button
+              type="button"
+              onClick={() => remove(line.id)}
+              disabled={lines.length === 1}
+              className="text-ink-3 hover:text-rubis-deep disabled:opacity-30"
+              aria-label="Supprimer cette ligne"
+            >
+              <Trash2 size={14} />
+            </button>
+          </div>
+        );
+      })}
+    </div>
+  );
+}
+
+// ============================================================================
+// TotalsBlock — récapitulatif HT / TVA / TTC
+// ============================================================================
+
+function TotalsBlock({
+  totals,
+}: {
+  totals: {
+    amountHtCents: number;
+    amountTvaCents: number;
+    amountTtcCents: number;
+  };
+}) {
+  const fmt = (cents: number) =>
+    (cents / 100).toLocaleString("fr-FR", {
+      style: "currency",
+      currency: "EUR",
+    });
+  return (
+    <div className="flex flex-col gap-1 self-end rounded-default border border-line bg-cream-2 px-4 py-3 text-[14px] sm:min-w-[280px]">
+      <div className="flex justify-between text-ink-2">
+        <span>Total HT</span>
+        <span className="font-mono tabular-nums">{fmt(totals.amountHtCents)}</span>
+      </div>
+      <div className="flex justify-between text-ink-2">
+        <span>TVA</span>
+        <span className="font-mono tabular-nums">{fmt(totals.amountTvaCents)}</span>
+      </div>
+      <div className="mt-1 flex justify-between border-t border-line pt-2 font-display font-bold text-ink">
+        <span>Total TTC</span>
+        <span className="font-mono tabular-nums">{fmt(totals.amountTtcCents)}</span>
+      </div>
+    </div>
+  );
+}
+
+// ============================================================================
+// computeTotals — mêmes règles d'arrondi que le serveur (cf. invoice_totals.ts)
+// ============================================================================
+
+function computeTotals(lines: InvoiceLineInput[]) {
+  let amountHt = 0;
+  let amountTva = 0;
+  for (const line of lines) {
+    const htCents = Math.round(line.quantity * line.unitPriceCents);
+    const tvaCents = Math.round((htCents * line.tvaRate) / 100);
+    amountHt += htCents;
+    amountTva += tvaCents;
+  }
+  return {
+    amountHtCents: amountHt,
+    amountTvaCents: amountTva,
+    amountTtcCents: amountHt + amountTva,
+  };
+}
+
+// ============================================================================
+// usePreview — POST /invoices/preview-pdf debounced, objectURL pour iframe
+// ============================================================================
+
+function usePreview(fields: {
+  clientId: string | null;
+  issueDate: string;
+  paymentTermsDays: number;
+  themeSlug: InvoiceThemeSlug;
+  accentColor: string;
+  lines: InvoiceLineInput[];
+  footerNotes: string;
+}) {
+  const [previewUrl, setPreviewUrl] = useState<string | null>(null);
+  const [previewError, setPreviewError] = useState<string | null>(null);
+  const [isRefreshing, setIsRefreshing] = useState(false);
+  const previousUrlRef = useRef<string | null>(null);
+
+  // Debounce 500ms — on attend que la frappe ralentisse avant de POST.
+  const debounced = useDebouncedValue(fields, 500);
+
+  useEffect(() => {
+    // Pré-conditions : un client sélectionné et au moins une ligne non-vide.
+    const hasUsableLines = debounced.lines.some(
+      (l) => l.description.trim() !== "" && l.unitPriceCents > 0,
+    );
+    if (!debounced.clientId || !hasUsableLines) {
+      setPreviewUrl(null);
+      setPreviewError(null);
+      return;
+    }
+
+    const ctrl = new AbortController();
+    setIsRefreshing(true);
+    setPreviewError(null);
+
+    const dueDate = addDays(
+      new Date(debounced.issueDate),
+      debounced.paymentTermsDays,
+    ).toISOString();
+
+    previewInvoicePdf(
+      {
+        clientId: debounced.clientId,
+        issueDate: new Date(debounced.issueDate).toISOString(),
+        dueDate,
+        paymentTermsDays: debounced.paymentTermsDays,
+        themeSlug: debounced.themeSlug,
+        accentColor: debounced.accentColor,
+        lines: debounced.lines,
+        footerNotes:
+          debounced.footerNotes.trim() === "" ? null : debounced.footerNotes,
+      },
+      ctrl.signal,
+    )
+      .then((blob) => {
+        const url = URL.createObjectURL(blob);
+        if (previousUrlRef.current) URL.revokeObjectURL(previousUrlRef.current);
+        previousUrlRef.current = url;
+        setPreviewUrl(url);
+        setIsRefreshing(false);
+      })
+      .catch((err) => {
+        if (err?.name === "AbortError") return;
+        setIsRefreshing(false);
+        setPreviewError(
+          err instanceof ApiError
+            ? err.message
+            : "Aperçu indisponible — vérifiez les champs.",
+        );
+      });
+
+    return () => ctrl.abort();
+  }, [debounced]);
+
+  // Cleanup au démontage.
+  useEffect(() => {
+    return () => {
+      if (previousUrlRef.current) URL.revokeObjectURL(previousUrlRef.current);
+    };
+  }, []);
+
+  return { previewUrl, previewError, isRefreshing };
+}
+
+/** useDebouncedValue — version générique de debounce sur une valeur. */
+function useDebouncedValue<T>(value: T, delayMs: number): T {
+  const [debounced, setDebounced] = useState(value);
+  useEffect(() => {
+    const id = setTimeout(() => setDebounced(value), delayMs);
+    return () => clearTimeout(id);
+  }, [value, delayMs]);
+  return debounced;
+}