diff --git a/services/api/app/main.py b/services/api/app/main.py
index 9de701a..0e3a505 100644
--- a/services/api/app/main.py
+++ b/services/api/app/main.py
@@ -6,6 +6,7 @@ import psycopg
 from fastapi import Depends, FastAPI, HTTPException, Request, Response, status
 from fastapi.responses import JSONResponse
 from psycopg import Connection
+from psycopg.types.json import Json
 
 from .config import settings
 from .db import get_connection
@@ -248,7 +249,7 @@ def admin_status(user_id: UUID, payload: StatusRequest, connection: Connection =
         if count <= 1:
             raise error("LAST_ADMIN_PROTECTED", "不能禁用最后一个可用管理员", 409)
     updated = connection.execute("UPDATE users SET status = %s, updated_at = now() WHERE id = %s RETURNING id, status", (payload.status, user_id)).fetchone()
-    connection.execute("INSERT INTO admin_audit_logs(actor_id, action, target_type, target_id, before_value, after_value, reason) VALUES (%s, 'user_status', 'user', %s, %s, %s, %s)", (actor["id"], user_id, {"status": target["status"]}, {"status": updated["status"]}, payload.reason))
+    connection.execute("INSERT INTO admin_audit_logs(actor_id, action, target_type, target_id, before_value, after_value, reason) VALUES (%s, 'user_status', 'user', %s, %s, %s, %s)", (actor["id"], user_id, Json({"status": target["status"]}), Json({"status": updated["status"]}), payload.reason))
     connection.commit()
     return updated
 
@@ -262,7 +263,7 @@ def admin_membership(user_id: UUID, payload: MembershipRequest, connection: Conn
     connection.execute("UPDATE membership_grants SET revoked_at = now() WHERE user_id = %s AND revoked_at IS NULL", (user_id,))
     grant = connection.execute("INSERT INTO membership_grants(user_id, plan, starts_at, expires_at, created_by, reason) VALUES (%s, %s, %s, %s, %s, %s) RETURNING id, plan, starts_at, expires_at", (user_id, payload.plan, starts_at, payload.expires_at, actor["id"], payload.reason)).fetchone()
     connection.execute("UPDATE users SET plan = %s, updated_at = now() WHERE id = %s", (payload.plan, user_id))
-    connection.execute("INSERT INTO admin_audit_logs(actor_id, action, target_type, target_id, before_value, after_value, reason) VALUES (%s, 'membership', 'user', %s, %s, %s, %s)", (actor["id"], user_id, {"plan": target["plan"]}, {"plan": payload.plan, "expires_at": payload.expires_at.isoformat() if payload.expires_at else None}, payload.reason))
+    connection.execute("INSERT INTO admin_audit_logs(actor_id, action, target_type, target_id, before_value, after_value, reason) VALUES (%s, 'membership', 'user', %s, %s, %s, %s)", (actor["id"], user_id, Json({"plan": target["plan"]}), Json({"plan": payload.plan, "expires_at": payload.expires_at.isoformat() if payload.expires_at else None}), payload.reason))
     connection.commit()
     return grant
 
@@ -278,6 +279,6 @@ def admin_quota(user_id: UUID, payload: QuotaAdjustmentRequest, connection: Conn
         raise error("IDEMPOTENCY_CONFLICT", "该调整已提交", 409)
     connection.execute("UPDATE quota_accounts SET adjustment = adjustment + %s, version = version + 1 WHERE id = %s", (payload.amount, quota["id"]))
     connection.execute("INSERT INTO usage_records(user_id, quota_account_id, type, amount, idempotency_key) VALUES (%s, %s, 'adjust', %s, %s)", (user_id, quota["id"], payload.amount, payload.idempotency_key))
-    connection.execute("INSERT INTO admin_audit_logs(actor_id, action, target_type, target_id, after_value, reason) VALUES (%s, 'quota_adjustment', 'user', %s, %s, %s)", (actor["id"], user_id, {"amount": payload.amount}, payload.reason))
+    connection.execute("INSERT INTO admin_audit_logs(actor_id, action, target_type, target_id, after_value, reason) VALUES (%s, 'quota_adjustment', 'user', %s, %s, %s)", (actor["id"], user_id, Json({"amount": payload.amount}), payload.reason))
     connection.commit()
     return {"status": "ok", "amount": payload.amount}