diff --git a/prisma/seed.ts b/prisma/seed.ts
index 63e843d..a35ffb7 100644
--- a/prisma/seed.ts
+++ b/prisma/seed.ts
@@ -428,90 +428,105 @@ async function main() {
     });
   }
 
-  // Bootstrap demo data uniquement si la DB est vide
-  const evalCount = await prisma.evaluation.count();
-  if (evalCount === 0) {
-    const template = await prisma.template.findUnique({
-      where: { id: "full-15" },
-    });
-    if (!template) throw new Error("Template not found");
+  // Upsert répondants (candidates) par nom : create si absent, update si existant. Ne vide pas les évaluations.
+  const template = await prisma.template.findUnique({
+    where: { id: "full-15" },
+  });
+  if (!template) throw new Error("Template not found");
 
-    await prisma.user.upsert({
-      where: { email: "admin@cars-front.local" },
-      create: {
-        email: "admin@cars-front.local",
-        name: "Admin User",
-        role: "admin",
+  await prisma.user.upsert({
+    where: { email: "admin@cars-front.local" },
+    create: {
+      email: "admin@cars-front.local",
+      name: "Admin User",
+      role: "admin",
+    },
+    update: {},
+  });
+
+  const dims = await prisma.templateDimension.findMany({
+    where: { templateId: template.id },
+    orderBy: { orderIndex: "asc" },
+  });
+
+  const repondants = [
+    {
+      name: "Alice Chen",
+      role: "Senior ML Engineer",
+      team: "Cars Front",
+      evaluator: "Jean Dupont",
+    },
+    {
+      name: "Bob Martin",
+      role: "Data Scientist",
+      team: "Cars Front",
+      evaluator: "Marie Curie",
+    },
+    {
+      name: "Carol White",
+      role: "AI Product Manager",
+      team: "Cars Data",
+      evaluator: "Jean Dupont",
+    },
+  ];
+
+  for (let i = 0; i < repondants.length; i++) {
+    const r = repondants[i];
+    const existing = await prisma.evaluation.findFirst({
+      where: {
+        candidateName: r.name,
+        evaluatorName: r.evaluator,
       },
-      update: {},
+      orderBy: { evaluationDate: "desc" },
     });
 
-    const dims = await prisma.templateDimension.findMany({
-      where: { templateId: template.id },
-      orderBy: { orderIndex: "asc" },
-    });
+    const evalData = {
+      candidateName: r.name,
+      candidateRole: r.role,
+      candidateTeam: r.team,
+      evaluatorName: r.evaluator,
+      evaluationDate: new Date(2025, 1, 15 + i),
+      templateId: template.id,
+      status: i === 0 ? "submitted" : "draft",
+      findings:
+        i === 0
+          ? "Bonne maîtrise des outils et des prompts. Conception et exploration à renforcer. Alignement NFR correct."
+          : null,
+      recommendations:
+        i === 0
+          ? "Encourager le mode plan avant implémentation. Veille sur les workflows IA."
+          : null,
+    };
 
-    const candidates = [
-      {
-        name: "Alice Chen",
-        role: "Senior ML Engineer",
-        team: "Cars Front",
-        evaluator: "Jean Dupont",
-      },
-      {
-        name: "Bob Martin",
-        role: "Data Scientist",
-        team: "Cars Front",
-        evaluator: "Marie Curie",
-      },
-      {
-        name: "Carol White",
-        role: "AI Product Manager",
-        team: "Cars Data",
-        evaluator: "Jean Dupont",
-      },
-    ];
+    let evaluation;
+    if (existing) {
+      evaluation = await prisma.evaluation.update({
+        where: { id: existing.id },
+        data: evalData,
+      });
+      await prisma.dimensionScore.deleteMany({ where: { evaluationId: existing.id } });
+    } else {
+      evaluation = await prisma.evaluation.create({
+        data: evalData,
+      });
+    }
 
-    for (let i = 0; i < candidates.length; i++) {
-      const c = candidates[i];
-      const evaluation = await prisma.evaluation.create({
+    for (const d of dims) {
+      const score = 2 + Math.floor(Math.random() * 3);
+      const { justification, examplesObserved } = getDemoResponse(d.slug, score);
+      await prisma.dimensionScore.create({
         data: {
-          candidateName: c.name,
-          candidateRole: c.role,
-          candidateTeam: c.team,
-          evaluatorName: c.evaluator,
-          evaluationDate: new Date(2025, 1, 15 + i),
-          templateId: template.id,
-          status: i === 0 ? "submitted" : "draft",
-          findings:
-            i === 0
-              ? "Bonne maîtrise des outils et des prompts. Conception et exploration à renforcer. Alignement NFR correct."
-              : null,
-          recommendations:
-            i === 0
-              ? "Encourager le mode plan avant implémentation. Veille sur les workflows IA."
-              : null,
+          evaluationId: evaluation.id,
+          dimensionId: d.id,
+          score,
+          justification,
+          examplesObserved,
+          confidence: ["low", "med", "high"][Math.floor(Math.random() * 3)],
         },
       });
-      for (const d of dims) {
-        const score = 2 + Math.floor(Math.random() * 3);
-        const { justification, examplesObserved } = getDemoResponse(d.slug, score);
-        await prisma.dimensionScore.create({
-          data: {
-            evaluationId: evaluation.id,
-            dimensionId: d.id,
-            score,
-            justification,
-            examplesObserved,
-            confidence: ["low", "med", "high"][Math.floor(Math.random() * 3)],
-          },
-        });
-      }
     }
-    console.log("Seed complete: templates synced, demo evaluations created");
-  } else {
-    console.log("Seed complete: templates synced, evaluations preserved");
   }
+  console.log("Seed complete: templates synced, répondants upserted (évaluations non vidées)");
 }
 
 main()