diff --git a/server/templates/aptReduce.test.ts b/server/templates/aptReduce.test.ts
new file mode 100644
index 0000000..759ba85
--- /dev/null
+++ b/server/templates/aptReduce.test.ts
@@ -0,0 +1,29 @@
+// server/templates/aptReduce.test.ts
+import { describe, it, expect } from "vitest";
+import { reduceAptLines } from "./aptReduce.js";
+
+describe("reduceAptLines", () => {
+  it("ne garde que les lignes utiles", () => {
+    const raw = [
+      "Reading package lists...",
+      "Building dependency tree...",
+      "Inst pve-manager [8.4-1] (8.4-3 Proxmox VE:8.x [amd64])",
+      "blabla inutile",
+      "Conf pve-manager (8.4-3 Proxmox VE:8.x [amd64])",
+      "E: Could not get lock",
+      "W: Some warning",
+      "dpkg: warning: x",
+    ].join("\n");
+    expect(reduceAptLines(raw)).toEqual([
+      "Inst pve-manager [8.4-1] (8.4-3 Proxmox VE:8.x [amd64])",
+      "Conf pve-manager (8.4-3 Proxmox VE:8.x [amd64])",
+      "E: Could not get lock",
+      "W: Some warning",
+      "dpkg: warning: x",
+    ]);
+  });
+
+  it("retourne un tableau vide si rien d'utile", () => {
+    expect(reduceAptLines("Reading package lists...\nDone")).toEqual([]);
+  });
+});
diff --git a/server/templates/aptReduce.ts b/server/templates/aptReduce.ts
new file mode 100644
index 0000000..544a410
--- /dev/null
+++ b/server/templates/aptReduce.ts
@@ -0,0 +1,11 @@
+// server/templates/aptReduce.ts
+const PREFIXES = ["Inst ", "Conf ", "Remv ", "Err ", "E:", "W:", "dpkg:"];
+const CONTAINS = ["reboot-required", "REBOOT_REQUIRED"];
+
+/** Garde uniquement les lignes informatives d'une sortie APT brute. */
+export function reduceAptLines(raw: string): string[] {
+  return raw
+    .split("\n")
+    .map((l) => l.trimEnd())
+    .filter((l) => PREFIXES.some((p) => l.startsWith(p)) || CONTAINS.some((c) => l.includes(c)));
+}