diff --git a/src/app/api/ai/context/route.ts b/src/app/api/ai/context/route.ts
index f637122..e9df5fb 100644
--- a/src/app/api/ai/context/route.ts
+++ b/src/app/api/ai/context/route.ts
@@ -2,6 +2,42 @@ import { NextResponse } from "next/server";
 import { db } from "@/db";
 import { aiSupplierContext } from "@/db/schema";
 import { eq } from "drizzle-orm";
+import fs from "fs";
+import path from "path";
+
+// File system fallback for environments without PostgreSQL
+const DATA_DIR = path.join(process.cwd(), "data");
+const FALLBACK_FILE_PATH = path.join(DATA_DIR, "ai-context.json");
+
+function ensureFallbackFileExists() {
+    if (!fs.existsSync(DATA_DIR)) {
+        fs.mkdirSync(DATA_DIR, { recursive: true });
+    }
+    if (!fs.existsSync(FALLBACK_FILE_PATH)) {
+        fs.writeFileSync(FALLBACK_FILE_PATH, JSON.stringify({}), "utf-8");
+    }
+}
+
+function getFallbackContext(codeFournisseur: string): string {
+    ensureFallbackFileExists();
+    try {
+        const data = JSON.parse(fs.readFileSync(FALLBACK_FILE_PATH, "utf-8"));
+        return data[codeFournisseur] || "";
+    } catch {
+        return "";
+    }
+}
+
+function saveFallbackContext(codeFournisseur: string, contextText: string) {
+    ensureFallbackFileExists();
+    try {
+        const data = JSON.parse(fs.readFileSync(FALLBACK_FILE_PATH, "utf-8"));
+        data[codeFournisseur] = contextText;
+        fs.writeFileSync(FALLBACK_FILE_PATH, JSON.stringify(data, null, 2), "utf-8");
+    } catch (err) {
+        console.error("Error saving fallback context:", err);
+    }
+}
 
 export async function GET(request: Request) {
     const { searchParams } = new URL(request.url);
@@ -19,9 +55,8 @@ export async function GET(request: Request) {
 
         return NextResponse.json({ context: result[0]?.context || "" });
     } catch (error) {
-        console.error("Error fetching AI context:", error);
-        // Fallback en cas d'erreur de BDD ou si la table n'est pas encore créée
-        return NextResponse.json({ context: "" });
+        console.warn("DB fetch failed, using fallback JSON for AI context.");
+        return NextResponse.json({ context: getFallbackContext(codeFournisseur) });
     }
 }
 
@@ -34,23 +69,28 @@ export async function POST(request: Request) {
             return NextResponse.json({ error: "Fournisseur manquant" }, { status: 400 });
         }
 
-        await db.insert(aiSupplierContext)
-            .values({
-                codeFournisseur,
-                context: context || "",
-                updatedAt: new Date()
-            })
-            .onConflictDoUpdate({
-                target: aiSupplierContext.codeFournisseur,
-                set: {
+        try {
+            await db.insert(aiSupplierContext)
+                .values({
+                    codeFournisseur,
                     context: context || "",
                     updatedAt: new Date()
-                }
-            });
+                })
+                .onConflictDoUpdate({
+                    target: aiSupplierContext.codeFournisseur,
+                    set: {
+                        context: context || "",
+                        updatedAt: new Date()
+                    }
+                });
+        } catch (dbError) {
+            console.warn("DB insert failed, saving to fallback JSON.", dbError);
+            saveFallbackContext(codeFournisseur, context || "");
+        }
 
         return NextResponse.json({ success: true });
     } catch (error) {
-        console.error("Error saving AI context:", error);
+        console.error("Error in AI context API:", error);
         return NextResponse.json({ error: "Erreur lors de la sauvegarde" }, { status: 500 });
     }
 }
diff --git a/src/app/globals.css b/src/app/globals.css
index 3e5528a..28d20c6 100644
--- a/src/app/globals.css
+++ b/src/app/globals.css
@@ -6,17 +6,26 @@
 
 /* ── Dark Mode (default) ── */
 :root {
-  /* Apple macOS dark exact values */
-  --bg-base: #000000;
-  --bg-surface: #111111;
-  --bg-elevated: #1c1c1e;
-  --bg-overlay: rgba(28, 28, 30, 0.85);
-  --border: rgba(255, 255, 255, 0.08);
-  --border-strong: rgba(255, 255, 255, 0.12);
+  /* Apple macOS dark aligned to Slate palette as per UX Spec */
+  --bg-base: #020617;
+  /* Slate 950 */
+  --bg-surface: #0f172a;
+  /* Slate 900 */
+  --bg-elevated: #1e293b;
+  /* Slate 800 */
+  --bg-overlay: rgba(15, 23, 42, 0.85);
+  /* Slate 900 with opacity */
+  --border: #334155;
+  /* Slate 700 */
+  --border-strong: #475569;
+  /* Slate 600 */
 
-  --text-primary: #f5f5f7;
-  --text-secondary: #a1a1a6;
-  --text-muted: #86868b;
+  --text-primary: #e2e8f0;
+  /* Slate 200 */
+  --text-secondary: #94a3b8;
+  /* Slate 400 */
+  --text-muted: #64748b;
+  /* Slate 500 */
 
   --accent: #2dd4bf;
   /* emerald-ish, Apple-tuned */
@@ -127,8 +136,13 @@
 }
 
 /* ── Surfaces & containers ── */
-.surface { background: var(--bg-surface); }
-.elevated { background: var(--bg-elevated); }
+.surface {
+  background: var(--bg-surface);
+}
+
+.elevated {
+  background: var(--bg-elevated);
+}
 
 .apple-card {
   background: var(--bg-surface);
@@ -206,33 +220,35 @@
 }
 
 .heatmap-low {
-  background: rgba(45, 212, 191, 0.08);
-  color: rgba(45, 212, 191, 0.70);
+  background: rgba(14, 165, 233, 0.08);
+  /* sky-500 */
+  color: rgba(14, 165, 233, 0.70);
 }
 
 .heatmap-mid {
-  background: rgba(45, 212, 191, 0.15);
-  color: rgba(45, 212, 191, 0.90);
+  background: rgba(14, 165, 233, 0.15);
+  color: rgba(14, 165, 233, 0.90);
 }
 
 .heatmap-high {
-  background: rgba(45, 212, 191, 0.25);
-  color: #2dd4bf;
+  background: rgba(14, 165, 233, 0.25);
+  color: #0ea5e9;
 }
 
 .light .heatmap-low {
-  background: rgba(13, 148, 136, 0.08);
-  color: #0f766e;
+  background: rgba(2, 132, 199, 0.08);
+  /* sky-600 */
+  color: #0369a1;
 }
 
 .light .heatmap-mid {
-  background: rgba(13, 148, 136, 0.14);
-  color: #0d9488;
+  background: rgba(2, 132, 199, 0.14);
+  color: #0284c7;
 }
 
 .light .heatmap-high {
-  background: rgba(13, 148, 136, 0.22);
-  color: #0f766e;
+  background: rgba(2, 132, 199, 0.22);
+  color: #0369a1;
 }
 
 /* ── Apple-style input ── */
@@ -263,7 +279,7 @@
   align-items: center;
   gap: 6px;
   padding: 8px 18px;
-  background: var(--accent);
+  background: var(--brand-solid);
   color: #fff;
   font-size: 13px;
   font-weight: 600;
diff --git a/src/features/grid/components/heatmap-cell.tsx b/src/features/grid/components/heatmap-cell.tsx
index 1e865bb..7b9f7f3 100644
--- a/src/features/grid/components/heatmap-cell.tsx
+++ b/src/features/grid/components/heatmap-cell.tsx
@@ -4,25 +4,22 @@ interface HeatmapCellProps {
     value: number | null;
 }
 
-function getHeatmapStyle(value: number | null): { background: string; color: string } {
-    if (value === null || value === 0) {
-        return { background: "var(--bg-elevated)", color: "var(--text-muted)" };
-    }
+function getHeatmapClass(value: number | null): string {
+    if (value === null || value === 0) return "heatmap-zero";
     const abs = Math.abs(value);
-    if (abs > 100) return { background: "rgba(45,212,191,0.22)", color: "var(--accent)" };
-    if (abs > 30) return { background: "rgba(45,212,191,0.14)", color: "var(--accent)" };
-    if (abs > 10) return { background: "rgba(45,212,191,0.08)", color: "var(--accent)" };
-    return { background: "var(--bg-elevated)", color: "var(--text-secondary)" };
+    if (abs > 100) return "heatmap-high";
+    if (abs > 30) return "heatmap-mid";
+    if (abs > 10) return "heatmap-low";
+    return "heatmap-zero";
 }
 
 export function HeatmapCell({ value }: HeatmapCellProps) {
-    const style = getHeatmapStyle(value);
+    const heatClass = getHeatmapClass(value);
     const display = value === null || value === 0 ? "—" : Math.round(Math.abs(value)).toString();
 
     return (
         <div
-            className="rounded text-center text-[12px] tabular-nums px-0.5 py-0.5 font-bold tracking-tighter transition-colors min-h-[24px] flex items-center justify-center font-mono-nums"
-            style={style}
+            className={`rounded text-center text-[12px] tabular-nums px-0.5 py-0.5 font-bold tracking-tighter transition-colors min-h-[24px] flex items-center justify-center font-mono-nums ${heatClass}`}
             title={value !== null ? `${Math.abs(value).toLocaleString("fr-FR")} unités` : "Aucune vente"}
         >
             {display}