diff --git a/scripts/yunohost_sync.py b/scripts/yunohost_sync.py
new file mode 100644
index 0000000..9be3685
--- /dev/null
+++ b/scripts/yunohost_sync.py
@@ -0,0 +1,119 @@
+"""Logique partagee entre sync-apps.py (CLI) et preview.py (endpoint /__catalog)
+pour recuperer et normaliser la liste des apps installees sur le serveur
+YunoHost via /etc/yunohost/portal/<domaine>.json.
+"""
+import json
+import subprocess
+from pathlib import Path
+
+PROJECT_ROOT = Path(__file__).resolve().parent.parent
+CONFIG_PATH = PROJECT_ROOT / "src" / "config.json"
+ENV_PATH = PROJECT_ROOT / ".env"
+
+PALETTE = [
+    "#1db9c3", "#ff5a1f", "#2094f3", "#ffc230", "#00a651", "#e6721a",
+    "#b71c1c", "#f39c12", "#0d3b66", "#3b8a8c", "#568d34", "#609926",
+    "#d24939", "#0066cc", "#8e44ad", "#16a085", "#c0392b", "#2c3e50",
+]
+
+
+def load_env():
+    env = {}
+    if not ENV_PATH.exists():
+        return env
+    for line in ENV_PATH.read_text(encoding="utf-8").splitlines():
+        line = line.strip()
+        if not line or line.startswith("#") or "=" not in line:
+            continue
+        key, value = line.split("=", 1)
+        env[key.strip()] = value.strip()
+    return env
+
+
+def sync_target(env, arg_target=None, arg_domain=None):
+    """Determine (ssh_target, domain, self_app_id) depuis .env ou arguments CLI."""
+    sync_ssh_user = env.get("SYNC_SSH_USER", "root")
+    sync_ssh_host = env.get("SYNC_SSH_HOST") or env.get("REMOTE_HOST")
+    portal_domain = env.get("PORTAL_DOMAIN", "")
+    self_app_id = env.get("REMOTE_USER", "")
+
+    ssh_target = arg_target or (f"{sync_ssh_user}@{sync_ssh_host}" if sync_ssh_host else None)
+    domain = arg_domain or portal_domain
+    return ssh_target, domain, self_app_id
+
+
+def color_of(name):
+    h = 0
+    for ch in name:
+        h = (h * 31 + ord(ch)) & 0xFFFFFFFF
+    return PALETTE[h % len(PALETTE)]
+
+
+def initials_of(name):
+    words = name.strip().split()
+    if len(words) == 1:
+        return words[0][:2].upper()
+    return (words[0][0] + words[1][0]).upper()
+
+
+def normalize_url(url):
+    return url.replace("https://", "").replace("http://", "").rstrip("/").lower()
+
+
+def known_urls(config):
+    urls = set()
+    for app in config.get("pinned", []):
+        urls.add(normalize_url(app["url"]))
+    for group in config.get("groups", []):
+        for app in group["apps"]:
+            urls.add(normalize_url(app["url"]))
+    for app in config.get("ungrouped", []):
+        urls.add(normalize_url(app["url"]))
+    return urls
+
+
+def fetch_remote_apps(ssh_target, domain):
+    cmd = ["ssh", "-o", "BatchMode=yes", "-o", "ConnectTimeout=5", ssh_target, f"cat /etc/yunohost/portal/{domain}.json"]
+    result = subprocess.run(cmd, capture_output=True, text=True)
+    if result.returncode != 0:
+        raise RuntimeError(result.stderr.strip() or "echec SSH")
+    return json.loads(result.stdout)
+
+
+def build_app_list(remote, domain, self_app_id, exclude_urls=frozenset()):
+    """Transforme la reponse brute YunoHost en liste d'apps normalisees
+    (id/name/url/color/initials/icon), triee par nom, en excluant l'app
+    elle-meme et celles dont l'URL est deja connue (exclude_urls)."""
+    remote_apps = remote.get("apps", {})
+    apps = []
+    for perm_key, info in remote_apps.items():
+        if not perm_key.endswith(".main"):
+            continue
+        app_id = perm_key[: -len(".main")]
+        if app_id == self_app_id:
+            continue
+
+        url = info["url"]
+        if not url.startswith("http"):
+            url = "https://" + url
+        if not url.endswith("/"):
+            url += "/"
+
+        if normalize_url(url) in exclude_urls:
+            continue
+
+        name = info.get("label", app_id)
+        app = {
+            "id": app_id,
+            "name": name,
+            "url": url,
+            "color": color_of(name),
+            "initials": initials_of(name),
+        }
+        logo = info.get("logo")
+        if logo:
+            app["icon"] = f"https://{domain}{logo}"
+        apps.append(app)
+
+    apps.sort(key=lambda a: a["name"].lower())
+    return apps