diff --git a/frontend/src/api/sites.ts b/frontend/src/api/sites.ts
index 5682b81f..cf99c9e6 100644
--- a/frontend/src/api/sites.ts
+++ b/frontend/src/api/sites.ts
@@ -1,5 +1,5 @@
 import { apiGet } from "./axios";
 import type { ApiListResponse } from "../types/api";
 
-export const fetchSites = (studyId: string) =>
-  apiGet<ApiListResponse<any>>(`/api/v1/studies/${studyId}/sites/`);
+export const fetchSites = (studyId: string, params?: Record<string, any>) =>
+  apiGet<ApiListResponse<any>>(`/api/v1/studies/${studyId}/sites/`, { params });
diff --git a/frontend/src/api/users.ts b/frontend/src/api/users.ts
new file mode 100644
index 00000000..ffbd1aba
--- /dev/null
+++ b/frontend/src/api/users.ts
@@ -0,0 +1,5 @@
+import { apiGet } from "./axios";
+import type { ApiListResponse } from "../types/api";
+
+export const fetchUsers = (params?: Record<string, any>) =>
+  apiGet<ApiListResponse<any>>("/api/v1/users", { params });
diff --git a/frontend/src/components/AeForm.vue b/frontend/src/components/AeForm.vue
index 37106730..dbb71d1b 100644
--- a/frontend/src/components/AeForm.vue
+++ b/frontend/src/components/AeForm.vue
@@ -2,14 +2,7 @@
   <el-dialog :title="isEdit ? '编辑 AE' : '新增 AE'" v-model="visible" width="600px" @close="onClose">
     <el-form ref="formRef" :model="form" :rules="rules" label-width="120px">
       <el-form-item label="受试者" prop="subject_id">
-        <el-select v-model="form.subject_id" placeholder="可留空" clearable filterable>
-          <el-option
-            v-for="s in subjects || []"
-            :key="s.id"
-            :label="s.subject_no || s.id"
-            :value="s.id"
-          />
-        </el-select>
+        <SubjectSelect v-model="form.subject_id" :study-id="study.currentStudy?.id || null" placeholder="可留空" />
       </el-form-item>
       <el-form-item label="事件描述" prop="term">
         <el-input v-model="form.term" />
@@ -45,14 +38,13 @@ import type { FormInstance, FormRules } from "element-plus";
 import { ElMessage } from "element-plus";
 import { createAe, updateAe } from "../api/aes";
 import { useStudyStore } from "../store/study";
+import SubjectSelect from "./selectors/SubjectSelect.vue";
 
-interface Props {
+const props = defineProps<{
   modelValue: boolean;
   ae?: Record<string, any>;
   subjects?: any[];
-}
-
-const props = defineProps<Props>();
+}>();
 const emit = defineEmits(["update:modelValue", "success"]);
 
 const visible = computed({
@@ -125,16 +117,11 @@ const onSubmit = async () => {
     submitting.value = true;
     try {
       const payload: Record<string, any> = {};
-      const uuidLike = /^[0-9a-fA-F-]{36}$/;
       Object.entries(form).forEach(([k, v]) => {
         if (v !== "" && v !== null && v !== undefined) {
           payload[k] = v;
         }
       });
-      if (payload.subject_id && !uuidLike.test(String(payload.subject_id))) {
-        ElMessage.warning("受试者ID格式不正确，已忽略");
-        delete payload.subject_id;
-      }
       if (isEdit.value && props.ae) {
         await updateAe(study.currentStudy.id, props.ae.id, payload);
       } else {
diff --git a/frontend/src/components/DataQueryForm.vue b/frontend/src/components/DataQueryForm.vue
index 9e011b5d..a4e31ea8 100644
--- a/frontend/src/components/DataQueryForm.vue
+++ b/frontend/src/components/DataQueryForm.vue
@@ -5,9 +5,7 @@
         <el-input v-model="form.title" />
       </el-form-item>
       <el-form-item label="受试者" prop="subject_id">
-        <el-select v-model="form.subject_id" placeholder="可留空" clearable filterable>
-          <el-option v-for="s in subjects || []" :key="s.id" :label="s.subject_no || s.id" :value="s.id" />
-        </el-select>
+        <SubjectSelect v-model="form.subject_id" :study-id="study.currentStudy?.id || null" placeholder="可选" />
       </el-form-item>
       <el-form-item label="类别" prop="category">
         <el-select v-model="form.category" placeholder="请选择">
@@ -25,7 +23,7 @@
         </el-select>
       </el-form-item>
       <el-form-item label="指派给" prop="assigned_to">
-        <el-input v-model="form.assigned_to" placeholder="用户ID，可留空" />
+        <UserSelect v-model="form.assigned_to" placeholder="可选" />
       </el-form-item>
       <el-form-item label="截止日期" prop="due_date">
         <el-date-picker v-model="form.due_date" type="date" value-format="YYYY-MM-DD" />
@@ -47,14 +45,13 @@ import type { FormInstance, FormRules } from "element-plus";
 import { ElMessage } from "element-plus";
 import { createDataQuery, updateDataQuery } from "../api/dataQueries";
 import { useStudyStore } from "../store/study";
+import SubjectSelect from "./selectors/SubjectSelect.vue";
+import UserSelect from "./selectors/UserSelect.vue";
 
-interface Props {
+const props = defineProps<{
   modelValue: boolean;
   query?: Record<string, any>;
-  subjects?: any[];
-}
-
-const props = defineProps<Props>();
+}>();
 const emit = defineEmits(["update:modelValue", "success"]);
 
 const visible = computed({
diff --git a/frontend/src/components/FinanceForm.vue b/frontend/src/components/FinanceForm.vue
index ff14a1e0..4c196353 100644
--- a/frontend/src/components/FinanceForm.vue
+++ b/frontend/src/components/FinanceForm.vue
@@ -21,11 +21,11 @@
       <el-form-item label="发生日期" prop="occur_date">
         <el-date-picker v-model="form.occur_date" type="date" value-format="YYYY-MM-DD" />
       </el-form-item>
-      <el-form-item label="中心ID">
-        <el-input v-model="form.site_id" placeholder="可选" />
+      <el-form-item label="中心">
+        <SiteSelect v-model="form.site_id" :study-id="study.currentStudy?.id || null" placeholder="可选" />
       </el-form-item>
-      <el-form-item label="受试者ID">
-        <el-input v-model="form.subject_id" placeholder="可选" />
+      <el-form-item label="受试者">
+        <SubjectSelect v-model="form.subject_id" :study-id="study.currentStudy?.id || null" placeholder="可选" />
       </el-form-item>
     </el-form>
     <template #footer>
@@ -40,6 +40,8 @@ import { computed, reactive, ref, watch } from "vue";
 import { ElMessage, ElMessageBox, FormInstance, FormRules } from "element-plus";
 import { useStudyStore } from "../store/study";
 import { createFinanceItem, updateFinanceItem } from "../api/finance";
+import SiteSelect from "./selectors/SiteSelect.vue";
+import SubjectSelect from "./selectors/SubjectSelect.vue";
 
 const props = defineProps<{ modelValue: boolean; item?: any }>();
 const emit = defineEmits(["update:modelValue", "success"]);
diff --git a/frontend/src/components/ImpTransactionForm.vue b/frontend/src/components/ImpTransactionForm.vue
index 612be9bd..aa0fb765 100644
--- a/frontend/src/components/ImpTransactionForm.vue
+++ b/frontend/src/components/ImpTransactionForm.vue
@@ -2,7 +2,7 @@
   <el-dialog :model-value="modelValue" title="新增交易" width="560px" @close="close">
     <el-form ref="formRef" :model="form" :rules="rules" label-width="120px">
       <el-form-item label="中心" prop="site_id">
-        <el-input v-model="form.site_id" placeholder="Site ID" />
+        <SiteSelect v-model="form.site_id" :study-id="study.currentStudy?.id || null" />
       </el-form-item>
       <el-form-item label="批次" prop="batch_id">
         <el-select v-model="form.batch_id" placeholder="请选择批次">
@@ -17,8 +17,12 @@
       <el-form-item label="数量" prop="quantity">
         <el-input-number v-model="form.quantity" :min="1" :step="1" />
       </el-form-item>
-      <el-form-item label="受试者ID" :required="form.tx_type === 'DISPENSE'">
-        <el-input v-model="form.subject_id" placeholder="DISPENSE 时必填" />
+      <el-form-item label="受试者" :required="form.tx_type === 'DISPENSE'">
+        <SubjectSelect
+          v-model="form.subject_id"
+          :study-id="study.currentStudy?.id || null"
+          placeholder="DISPENSE 时必填"
+        />
       </el-form-item>
       <el-form-item label="日期" prop="tx_date">
         <el-date-picker v-model="form.tx_date" type="date" value-format="YYYY-MM-DD" />
@@ -42,6 +46,8 @@ import { computed, reactive, ref, watch } from "vue";
 import { ElMessage, FormInstance, FormRules } from "element-plus";
 import { useStudyStore } from "../store/study";
 import { createImpTransaction } from "../api/impTransactions";
+import SiteSelect from "./selectors/SiteSelect.vue";
+import SubjectSelect from "./selectors/SubjectSelect.vue";
 
 const props = defineProps<{ modelValue: boolean; batches: any[] }>();
 const emit = defineEmits(["update:modelValue", "success"]);
@@ -91,7 +97,12 @@ const onSubmit = async () => {
   }
   submitting.value = true;
   try {
-    await createImpTransaction(study.currentStudy.id, form);
+    const payload = {
+      ...form,
+      site_id: form.site_id || null,
+      subject_id: form.subject_id || null,
+    };
+    await createImpTransaction(study.currentStudy.id, payload);
     ElMessage.success("创建成功");
     emit("success");
     close();
diff --git a/frontend/src/components/IssueForm.vue b/frontend/src/components/IssueForm.vue
index 64b8c35f..6e8d33b0 100644
--- a/frontend/src/components/IssueForm.vue
+++ b/frontend/src/components/IssueForm.vue
@@ -4,6 +4,9 @@
       <el-form-item label="标题" prop="title">
         <el-input v-model="form.title" />
       </el-form-item>
+      <el-form-item label="受试者">
+        <SubjectSelect v-model="form.subject_id" :study-id="study.currentStudy?.id || null" placeholder="可选" />
+      </el-form-item>
       <el-form-item label="类别" prop="category">
         <el-select v-model="form.category" placeholder="请选择">
           <el-option v-for="c in categories" :key="c" :label="c" :value="c" />
@@ -34,6 +37,7 @@ import type { FormInstance, FormRules } from "element-plus";
 import { ElMessage } from "element-plus";
 import { createIssue, updateIssue } from "../api/issues";
 import { useStudyStore } from "../store/study";
+import SubjectSelect from "./selectors/SubjectSelect.vue";
 
 interface Props {
   modelValue: boolean;
@@ -57,6 +61,7 @@ const levels = ["LOW", "MEDIUM", "HIGH", "CRITICAL"];
 
 const form = reactive({
   title: "",
+  subject_id: "",
   category: "ISSUE",
   level: "MEDIUM",
   due_date: "",
@@ -77,6 +82,7 @@ watch(
     if (val) {
       Object.assign(form, {
         title: val.title || "",
+        subject_id: val.subject_id || "",
         category: val.category || "ISSUE",
         level: val.level || "MEDIUM",
         due_date: val.due_date || "",
@@ -85,6 +91,7 @@ watch(
     } else {
       Object.assign(form, {
         title: "",
+        subject_id: "",
         category: "ISSUE",
         level: "MEDIUM",
         due_date: "",
diff --git a/frontend/src/components/TaskForm.vue b/frontend/src/components/TaskForm.vue
index adf665c1..bf3272ea 100644
--- a/frontend/src/components/TaskForm.vue
+++ b/frontend/src/components/TaskForm.vue
@@ -13,7 +13,7 @@
         </el-select>
       </el-form-item>
       <el-form-item label="负责人" prop="assignee_id">
-        <el-input v-model="form.assignee_id" placeholder="用户ID" />
+        <UserSelect v-model="form.assignee_id" placeholder="选择负责人" />
       </el-form-item>
       <el-form-item label="优先级" prop="priority">
         <el-select v-model="form.priority" placeholder="请选择">
@@ -42,6 +42,7 @@ import type { FormInstance, FormRules } from "element-plus";
 import { ElMessage } from "element-plus";
 import { createTask, updateTask } from "../api/tasks";
 import { useStudyStore } from "../store/study";
+import UserSelect from "./selectors/UserSelect.vue";
 
 interface Props {
   modelValue: boolean;
@@ -120,20 +121,11 @@ const onSubmit = async () => {
     submitting.value = true;
     try {
     const payload: Record<string, any> = {};
-    const uuidLike = /^[0-9a-fA-F-]{36}$/;
     Object.entries(form).forEach(([k, v]) => {
       if (v !== "" && v !== null && v !== undefined) {
         payload[k] = v;
       }
     });
-    if (payload.assignee_id && !uuidLike.test(String(payload.assignee_id))) {
-      ElMessage.warning("负责人ID 需为有效用户ID，已忽略该字段");
-      delete payload.assignee_id;
-    }
-    if (payload.milestone_id && !uuidLike.test(String(payload.milestone_id))) {
-      ElMessage.warning("里程碑无效，已忽略该字段");
-      delete payload.milestone_id;
-    }
       if (isEdit.value && props.task) {
         await updateTask(study.currentStudy.id, props.task.id, payload);
       } else {
diff --git a/frontend/src/components/selectors/SiteSelect.vue b/frontend/src/components/selectors/SiteSelect.vue
new file mode 100644
index 00000000..dfc0252a
--- /dev/null
+++ b/frontend/src/components/selectors/SiteSelect.vue
@@ -0,0 +1,90 @@
+<template>
+  <el-select
+    :model-value="modelValue"
+    filterable
+    remote
+    clearable
+    :remote-method="onSearch"
+    :loading="loading"
+    :placeholder="placeholder || '请选择中心'"
+    style="width: 100%"
+    :disabled="disabled || !studyId"
+    @update:model-value="(val) => emit('update:modelValue', val)"
+  >
+    <el-option v-for="s in options" :key="s.id" :label="formatSite(s)" :value="s.id" />
+    <template #empty>
+      <div class="empty">{{ loading ? "加载中..." : "无匹配结果" }}</div>
+    </template>
+  </el-select>
+</template>
+
+<script setup lang="ts">
+import { ElMessage } from "element-plus";
+import { computed, ref, watch } from "vue";
+import { fetchSites } from "../../api/sites";
+
+interface Props {
+  modelValue: string | null;
+  studyId: string | null;
+  placeholder?: string;
+  disabled?: boolean;
+}
+
+const props = defineProps<Props>();
+const emit = defineEmits(["update:modelValue"]);
+
+const options = ref<any[]>([]);
+const loading = ref(false);
+let timer: number | undefined;
+const disabled = computed(() => props.disabled ?? false);
+
+const formatSite = (s: any) => {
+  if (!s) return "";
+  return s.city ? `${s.name} (${s.city})` : s.name;
+};
+
+const load = async (keyword = "") => {
+  if (!props.studyId) {
+    options.value = [];
+    return;
+  }
+  loading.value = true;
+  try {
+    const { data } = await fetchSites(props.studyId, { keyword, limit: 20 });
+    options.value = data.items || data || [];
+  } catch (e: any) {
+    ElMessage.error(e?.response?.data?.message || "中心加载失败");
+  } finally {
+    loading.value = false;
+  }
+};
+
+const onSearch = (keyword: string) => {
+  if (timer) window.clearTimeout(timer);
+  timer = window.setTimeout(() => load(keyword), 300);
+};
+
+watch(
+  () => props.studyId,
+  () => {
+    load("");
+  },
+  { immediate: true }
+);
+
+watch(
+  () => props.modelValue,
+  (val) => {
+    if (val && options.value.length === 0) {
+      load("");
+    }
+  }
+);
+</script>
+
+<style scoped>
+.empty {
+  padding: 8px;
+  color: #999;
+}
+</style>
diff --git a/frontend/src/components/selectors/SubjectSelect.vue b/frontend/src/components/selectors/SubjectSelect.vue
new file mode 100644
index 00000000..50ea3203
--- /dev/null
+++ b/frontend/src/components/selectors/SubjectSelect.vue
@@ -0,0 +1,98 @@
+<template>
+  <el-select
+    :model-value="modelValue"
+    filterable
+    remote
+    clearable
+    :remote-method="onSearch"
+    :loading="loading"
+    :placeholder="placeholder || '请选择受试者'"
+    style="width: 100%"
+    :disabled="disabled || !studyId"
+    @update:model-value="(val) => emit('update:modelValue', val)"
+  >
+    <el-option
+      v-for="s in options"
+      :key="s.id"
+      :label="formatSubject(s)"
+      :value="s.id"
+    />
+    <template #empty>
+      <div class="empty">{{ loading ? "加载中..." : "无匹配结果" }}</div>
+    </template>
+  </el-select>
+</template>
+
+<script setup lang="ts">
+import { ElMessage } from "element-plus";
+import { computed, ref, watch } from "vue";
+import { fetchSubjects } from "../../api/subjects";
+
+interface Props {
+  modelValue: string | null;
+  studyId: string | null;
+  placeholder?: string;
+  status?: string;
+  disabled?: boolean;
+}
+
+const props = defineProps<Props>();
+const emit = defineEmits(["update:modelValue"]);
+
+const options = ref<any[]>([]);
+const loading = ref(false);
+let timer: number | undefined;
+const disabled = computed(() => props.disabled ?? false);
+
+const formatSubject = (s: any) => {
+  if (!s) return "";
+  return s.status ? `${s.subject_no || s.id} (${s.status})` : s.subject_no || s.id;
+};
+
+const load = async (keyword = "") => {
+  if (!props.studyId) {
+    options.value = [];
+    return;
+  }
+  loading.value = true;
+  try {
+    const params: Record<string, any> = { keyword, limit: 20 };
+    if (props.status) params.status = props.status;
+    const { data } = await fetchSubjects(props.studyId, params);
+    options.value = data.items || data || [];
+  } catch (e: any) {
+    ElMessage.error(e?.response?.data?.message || "受试者加载失败");
+  } finally {
+    loading.value = false;
+  }
+};
+
+const onSearch = (keyword: string) => {
+  if (timer) window.clearTimeout(timer);
+  timer = window.setTimeout(() => load(keyword), 300);
+};
+
+watch(
+  () => props.studyId,
+  () => {
+    load("");
+  },
+  { immediate: true }
+);
+
+watch(
+  () => props.modelValue,
+  (val) => {
+    if (val && options.value.length === 0) {
+      load("");
+    }
+  }
+);
+</script>
+
+<style scoped>
+.empty {
+  padding: 8px;
+  color: #999;
+}
+</style>
diff --git a/frontend/src/components/selectors/UserSelect.vue b/frontend/src/components/selectors/UserSelect.vue
new file mode 100644
index 00000000..0aea2bc2
--- /dev/null
+++ b/frontend/src/components/selectors/UserSelect.vue
@@ -0,0 +1,81 @@
+<template>
+  <el-select
+    :model-value="modelValue"
+    :multiple="multiple"
+    filterable
+    remote
+    clearable
+    :remote-method="onSearch"
+    :loading="loading"
+    :placeholder="placeholder || '请选择用户'"
+    :disabled="disabled"
+    style="width: 100%"
+    @update:model-value="(val) => emit('update:modelValue', val)"
+  >
+    <el-option
+      v-for="u in options"
+      :key="u.id"
+      :label="`${u.username}${u.role ? ' (' + u.role + ')' : ''}`"
+      :value="u.id"
+    />
+    <template #empty>
+      <div class="empty">{{ loading ? "加载中..." : "无匹配结果" }}</div>
+    </template>
+  </el-select>
+</template>
+
+<script setup lang="ts">
+import { ElMessage } from "element-plus";
+import { computed, ref, watch } from "vue";
+import { fetchUsers } from "../../api/users";
+
+interface Props {
+  modelValue: string | string[] | null;
+  placeholder?: string;
+  multiple?: boolean;
+  disabled?: boolean;
+}
+
+const props = defineProps<Props>();
+const emit = defineEmits(["update:modelValue"]);
+
+const options = ref<any[]>([]);
+const loading = ref(false);
+let timer: number | undefined;
+const disabled = computed(() => props.disabled ?? false);
+
+const load = async (keyword = "") => {
+  loading.value = true;
+  try {
+    const { data } = await fetchUsers({ keyword, limit: 20 });
+    options.value = data.items || data || [];
+  } catch (e: any) {
+    ElMessage.error(e?.response?.data?.message || "用户加载失败");
+  } finally {
+    loading.value = false;
+  }
+};
+
+const onSearch = (keyword: string) => {
+  if (timer) window.clearTimeout(timer);
+  timer = window.setTimeout(() => load(keyword), 300);
+};
+
+watch(
+  () => props.modelValue,
+  (val) => {
+    // 初次渲染时拉一版数据，确保已选项有 label
+    if (val && options.value.length === 0) {
+      load("");
+    }
+  },
+  { immediate: true }
+);
+</script>
+
+<style scoped>
+.empty {
+  padding: 8px;
+  color: #999;
+}
+</style>
diff --git a/frontend/src/views/Verification.vue b/frontend/src/views/Verification.vue
index 11472318..cd8e2fdd 100644
--- a/frontend/src/views/Verification.vue
+++ b/frontend/src/views/Verification.vue
@@ -6,7 +6,13 @@
           <el-option label="SDV" value="SDV" />
           <el-option label="SDR" value="SDR" />
         </el-select>
-        <el-input v-model="filters.site_id" placeholder="中心ID" style="width: 180px" @change="load" />
+        <SiteSelect
+          v-model="filters.site_id"
+          :study-id="study.currentStudy?.id || null"
+          placeholder="中心"
+          style="width: 220px"
+          @change="load"
+        />
         <div class="spacer" />
         <el-button v-if="canEdit" type="primary" @click="openCreate">新增进度</el-button>
       </div>
@@ -16,11 +22,15 @@
 
     <el-dialog :title="editForm.id ? '更新进度' : '新增进度'" v-model="showEdit" width="520px">
       <el-form :model="editForm" label-width="120px">
-        <el-form-item label="受试者ID">
-          <el-input v-model="editForm.subject_id" :disabled="!!editForm.id" />
+        <el-form-item label="受试者">
+          <SubjectSelect
+            v-model="editForm.subject_id"
+            :study-id="study.currentStudy?.id || null"
+            :disabled="!!editForm.id"
+          />
         </el-form-item>
-        <el-form-item label="中心ID">
-          <el-input v-model="editForm.site_id" />
+        <el-form-item label="中心">
+          <SiteSelect v-model="editForm.site_id" :study-id="study.currentStudy?.id || null" />
         </el-form-item>
         <el-form-item label="类型">
           <el-select v-model="editForm.level" placeholder="请选择">
@@ -53,6 +63,8 @@ import { fetchVerifications, upsertVerification } from "../api/verifications";
 import { useStudyStore } from "../store/study";
 import { useAuthStore } from "../store/auth";
 import VerificationTable from "../components/VerificationTable.vue";
+import SiteSelect from "../components/selectors/SiteSelect.vue";
+import SubjectSelect from "../components/selectors/SubjectSelect.vue";
 
 const study = useStudyStore();
 const auth = useAuthStore();
@@ -115,7 +127,7 @@ const submitEdit = async () => {
   try {
     await upsertVerification(study.currentStudy.id, {
       subject_id: editForm.value.subject_id,
-      site_id: editForm.value.site_id,
+      site_id: editForm.value.site_id || null,
       level: editForm.value.level,
       percent: editForm.value.percent,
       last_verified_at: editForm.value.last_verified_at,
diff --git a/pg_data/pg_wal/000000010000000000000001 b/pg_data/pg_wal/000000010000000000000001
index 619a7624..2bfff9e8 100644
Binary files a/pg_data/pg_wal/000000010000000000000001 and b/pg_data/pg_wal/000000010000000000000001 differ