diff --git a/app.py b/app.py
index f3413e5..6e0a2d7 100644
--- a/app.py
+++ b/app.py
@@ -122,6 +122,11 @@ class CreateEnrollmentSessionRequest(BaseModel):
     expires_at: str
 
 
+class RechargeEnrollmentSessionRequest(BaseModel):
+    additional_devices: int = 0
+    expires_at: str | None = None
+
+
 class CreateIsoBuildRequest(BaseModel):
     activation_code: str
     wifi_ssid: str | None = None
@@ -773,6 +778,20 @@ def fetch_organizations():
                 for org_id, name, created_at in cur.fetchall()
             ]
 
+def fetch_organization(organization_id: str):
+    with get_database_connection() as conn:
+        with conn.cursor() as cur:
+            cur.execute(
+                "SELECT id, name, created_at FROM organizations WHERE id = %s",
+                (organization_id,),
+            )
+            row = cur.fetchone()
+
+    if row is None:
+        return None
+
+    return {"id": str(row[0]), "name": row[1], "created_at": row[2].isoformat()}
+
 def create_organization(name: str):
     organization_id = uuid4()
 
@@ -1132,6 +1151,31 @@ def revoke_enrollment_session(session_id: str):
             )
             return cur.fetchone() is not None
 
+def recharge_enrollment_session(session_id: str, additional_devices: int, expires_at: str | None):
+    """
+    Phase 5 (Kundenplattform-Selfservice): eine bereits ausgeteilte,
+    personalisierte Kunden-ISO bettet die Enrollment-Session-Id fest als
+    Aktivierungscode ein (siehe build_customer_iso.sh) - Kontingent/
+    Gueltigkeit dieser Session zu erhoehen macht die ISO weiter nutzbar,
+    ohne dass eine neue gebaut/neu verteilt werden muss. additional_devices
+    wird auf max_devices addiert (nicht ersetzt - "aufladen", nicht
+    "neu setzen"), expires_at ersetzt den bisherigen Wert, wenn angegeben.
+    """
+
+    with get_database_connection() as conn:
+        with conn.cursor() as cur:
+            cur.execute(
+                """
+                UPDATE enrollment_sessions
+                SET max_devices = max_devices + %s,
+                    expires_at = COALESCE(%s, expires_at)
+                WHERE id = %s AND revoked_at IS NULL
+                RETURNING id
+                """,
+                (additional_devices, expires_at, session_id),
+            )
+            return cur.fetchone() is not None
+
 def iso_build_row_to_dict(row) -> dict:
     (build_id, organization_id, status, output_filename, error_message,
      created_at, started_at, finished_at) = row
@@ -1659,6 +1703,19 @@ def create_organization_endpoint(
     return {"success": True, "organization": create_organization(payload.name)}
 
 
+@app.get("/api/v1/organizations/{organization_id}")
+def get_organization_endpoint(organization_id: str, authorization: str | None = Header(default=None)):
+    if not require_service_token(authorization):
+        return {"success": False, "error": "unauthorized", "message": "Fehlendes oder ungültiges Service-Token."}
+
+    organization = fetch_organization(organization_id)
+
+    if organization is None:
+        return {"success": False, "error": "organization_not_found", "message": "Die Organisation wurde nicht gefunden."}
+
+    return {"success": True, "organization": organization}
+
+
 @app.patch("/api/v1/organizations/{organization_id}")
 def update_organization_endpoint(
     organization_id: str,
@@ -1887,6 +1944,26 @@ def revoke_enrollment_session_endpoint(session_id: str, authorization: str | Non
     return {"success": True}
 
 
+@app.patch("/api/v1/enrollment-sessions/{session_id}")
+def recharge_enrollment_session_endpoint(
+    session_id: str,
+    payload: RechargeEnrollmentSessionRequest,
+    authorization: str | None = Header(default=None),
+):
+    if not require_service_token(authorization):
+        return {"success": False, "error": "unauthorized", "message": "Fehlendes oder ungültiges Service-Token."}
+
+    if payload.additional_devices < 0:
+        return {"success": False, "error": "invalid_request", "message": "additional_devices darf nicht negativ sein."}
+
+    recharged = recharge_enrollment_session(session_id, payload.additional_devices, payload.expires_at)
+
+    if not recharged:
+        return {"success": False, "error": "not_found", "message": "Enrollment Session wurde nicht gefunden oder ist widerrufen."}
+
+    return {"success": True}
+
+
 @app.get("/api/v1/organizations/{organization_id}/iso-builds")
 def list_iso_builds(organization_id: str, authorization: str | None = Header(default=None)):
     if not require_service_token(authorization):