diff --git a/docs/changelog/2026-06-12-server-agent-action-hint.md b/docs/changelog/2026-06-12-server-agent-action-hint.md
new file mode 100644
index 00000000..0653d6cd
--- /dev/null
+++ b/docs/changelog/2026-06-12-server-agent-action-hint.md
@@ -0,0 +1,33 @@
+# 2026-06-12 新服务器 Agent 安装/升级提示
+
+## 摘要
+
+新添加的服务器不再因预生成 `agent_api_key` 误显示「离线」；列表与展开详情明确提示需安装或升级 Agent，并提供一键操作。
+
+## 动机
+
+用户添加服务器后 CPU/内存/心跳为空，界面无指引。根因：仅有 DB 中的 API Key 被当作「已装 Agent」，实际从未安装。
+
+## 涉及文件
+
+- `server/utils/agent_version.py` — `agent_is_installed`、`compute_agent_guidance`
+- `server/api/servers.py` — 列表/详情返回 `agent_action*`；状态判定修正
+- `frontend/src/components/servers/ServerAgentHint.vue` — 提示条（新增）
+- `frontend/src/components/servers/ServerInlineDetail.vue` — 展开详情提示
+- `frontend/src/pages/ServersPage.vue` — 列表「需安装/需升级」芯片、单台安装/升级
+- `frontend/src/composables/servers/useServerFormDialog.ts` — 创建后 toast
+- `frontend/src/types/api.ts` — 类型
+- `tests/test_agent_version.py` — 单测
+
+## 迁移 / 重启
+
+需重启 API；前端构建部署。
+
+## 验证
+
+```bash
+.venv/bin/pytest tests/test_agent_version.py -q
+cd frontend && npm run type-check
+```
+
+添加服务器 → 状态应为「未知」→ 展开行见「尚未安装 Agent」→ 点「安装 Agent」。
diff --git a/frontend/src/components/servers/ServerAgentHint.vue b/frontend/src/components/servers/ServerAgentHint.vue
new file mode 100644
index 00000000..da616654
--- /dev/null
+++ b/frontend/src/components/servers/ServerAgentHint.vue
@@ -0,0 +1,68 @@
+<script setup lang="ts">
+import type { ServerAgentAction } from '@/types/api'
+
+const props = defineProps<{
+  action?: ServerAgentAction | null
+  message?: string | null
+  compact?: boolean
+  loading?: boolean
+}>()
+
+defineEmits<{
+  install: []
+  upgrade: []
+  diagnose: []
+}>()
+
+function alertType(action: ServerAgentAction | null | undefined): 'info' | 'warning' | 'error' {
+  if (action === 'install') return 'info'
+  if (action === 'upgrade') return 'warning'
+  if (action === 'offline') return 'error'
+  return 'info'
+}
+</script>
+
+<template>
+  <v-alert
+    v-if="props.action && props.action !== 'ok' && props.message"
+    :type="alertType(props.action)"
+    variant="tonal"
+    :density="props.compact ? 'compact' : 'default'"
+    class="mb-0"
+  >
+    <div class="d-flex flex-wrap align-center ga-2">
+      <span class="text-body-2">{{ props.message }}</span>
+      <v-spacer v-if="!props.compact" />
+      <div class="d-flex ga-1 flex-shrink-0">
+        <v-btn
+          v-if="props.action === 'install'"
+          size="small"
+          variant="flat"
+          color="primary"
+          :loading="props.loading"
+          @click="$emit('install')"
+        >
+          安装 Agent
+        </v-btn>
+        <v-btn
+          v-if="props.action === 'upgrade'"
+          size="small"
+          variant="flat"
+          color="warning"
+          :loading="props.loading"
+          @click="$emit('upgrade')"
+        >
+          升级 Agent
+        </v-btn>
+        <v-btn
+          v-if="props.action === 'offline'"
+          size="small"
+          variant="text"
+          @click="$emit('diagnose')"
+        >
+          诊断
+        </v-btn>
+      </div>
+    </div>
+  </v-alert>
+</template>
diff --git a/frontend/src/components/servers/ServerInlineDetail.vue b/frontend/src/components/servers/ServerInlineDetail.vue
index ddc82f98..c800d0a3 100644
--- a/frontend/src/components/servers/ServerInlineDetail.vue
+++ b/frontend/src/components/servers/ServerInlineDetail.vue
@@ -1,5 +1,15 @@
 <template>
   <div class="server-inline-detail pa-3 rounded-b-lg">
+    <ServerAgentHint
+      class="mb-3"
+      :action="displayServer.agent_action"
+      :message="displayServer.agent_action_message"
+      :loading="props.agentActionLoading"
+      @install="$emit('install-agent')"
+      @upgrade="$emit('upgrade-agent')"
+      @diagnose="$emit('diagnose-agent')"
+    />
+
     <div class="d-flex flex-wrap align-center ga-2 mb-3">
       <v-chip
         :color="statusChipColor(displayServer.status)"
@@ -111,14 +121,19 @@ import type {
 } from '@/types/api'
 import { formatDateTimeBeijing } from '@/utils/datetime'
 import ServerMetricSparklines from '@/components/servers/ServerMetricSparklines.vue'
+import ServerAgentHint from '@/components/servers/ServerAgentHint.vue'
 
 const props = defineProps<{
   server: ServerApiItem
   active?: boolean
+  agentActionLoading?: boolean
 }>()
 
 defineEmits<{
   'edit-path': []
+  'install-agent': []
+  'upgrade-agent': []
+  'diagnose-agent': []
 }>()
 
 const detail = ref<ServerApiItem | null>(null)
diff --git a/frontend/src/composables/servers/useServerFormDialog.ts b/frontend/src/composables/servers/useServerFormDialog.ts
index e4b76685..10499140 100644
--- a/frontend/src/composables/servers/useServerFormDialog.ts
+++ b/frontend/src/composables/servers/useServerFormDialog.ts
@@ -246,6 +246,11 @@ export function useServerFormDialog(onSaved: () => void) {
           )
           showScriptSubmitToast('新服务器初始化已在后台执行（sudo + 路径探测）')
         }
+        if (created.agent_action === 'install') {
+          showScriptSubmitToast(
+            created.agent_action_message || '请展开服务器行并点击「安装 Agent」以采集 CPU/内存等指标',
+          )
+        }
       }
       close()
       onSaved()
diff --git a/frontend/src/pages/ServersPage.vue b/frontend/src/pages/ServersPage.vue
index 96759edf..53829d85 100644
--- a/frontend/src/pages/ServersPage.vue
+++ b/frontend/src/pages/ServersPage.vue
@@ -236,7 +236,29 @@
         </template>
 
         <template #item.agent_version="{ item }">
-          <span class="text-medium-emphasis">{{ item.agent_version || '—' }}</span>
+          <div>
+            <span class="text-medium-emphasis">{{ item.agent_version || '—' }}</span>
+            <v-chip
+              v-if="item.agent_action === 'install'"
+              size="x-small"
+              color="info"
+              variant="tonal"
+              label
+              class="mt-1"
+            >
+              需安装
+            </v-chip>
+            <v-chip
+              v-else-if="item.agent_action === 'upgrade'"
+              size="x-small"
+              color="warning"
+              variant="tonal"
+              label
+              class="mt-1"
+            >
+              需升级
+            </v-chip>
+          </div>
         </template>
 
         <template #item.last_heartbeat="{ item }">
@@ -278,7 +300,11 @@
               <ServerInlineDetail
                 :server="item"
                 :active="expandedMainIds.includes(item.id)"
+                :agent-action-loading="agentActionLoadingId === item.id"
                 @edit-path="startEditPath(item)"
+                @install-agent="installAgentOne(item)"
+                @upgrade-agent="upgradeAgentOne(item)"
+                @diagnose-agent="openAgentDiagnose(item)"
               />
             </td>
           </tr>
@@ -1528,6 +1554,7 @@ function openFiles(item: ServerApiItem) {
 const showAgentDiagnose = ref(false)
 const agentDiagnoseLoading = ref(false)
 const agentDiagnoseLoadingId = ref<number | null>(null)
+const agentActionLoadingId = ref<number | null>(null)
 const agentDiagnoseResult = ref<AgentDiagnoseResult | null>(null)
 const agentDiagnoseTarget = ref<ServerApiItem | null>(null)
 
@@ -1548,6 +1575,31 @@ async function openAgentDiagnose(item: ServerApiItem) {
   }
 }
 
+async function installAgentOne(item: ServerApiItem) {
+  agentActionLoadingId.value = item.id
+  try {
+    await http.post(`/servers/${item.id}/install-agent`, {})
+    snackbar(`Agent 安装完成：${item.name}`, 'success')
+    await _load()
+  } catch (e: unknown) {
+    snackbar(formatApiError(e, '安装 Agent 失败'), 'error')
+  } finally {
+    agentActionLoadingId.value = null
+  }
+}
+
+async function upgradeAgentOne(item: ServerApiItem) {
+  agentActionLoadingId.value = item.id
+  try {
+    await submitServerBatchJob('upgrade-agent', [item.id])
+    snackbar(`已提交 Agent 升级：${item.name}`, 'success')
+  } catch (e: unknown) {
+    snackbar(formatApiError(e, '提交升级失败'), 'error')
+  } finally {
+    agentActionLoadingId.value = null
+  }
+}
+
 function editServer(item: ServerApiItem) {
   void openEditServerDialog(item)
 }
diff --git a/frontend/src/types/api.ts b/frontend/src/types/api.ts
index 845ad5a8..b97e6e39 100644
--- a/frontend/src/types/api.ts
+++ b/frontend/src/types/api.ts
@@ -149,6 +149,8 @@ export interface FilesCapabilityResult {
 }
 
 /** Server item from /api/servers/ */
+export type ServerAgentAction = 'install' | 'upgrade' | 'offline' | 'ok'
+
 export interface ServerApiItem {
   id: number
   name: string
@@ -175,6 +177,9 @@ export interface ServerApiItem {
   last_heartbeat: string | null
   agent_version: string | null
   status: string
+  agent_action?: ServerAgentAction
+  agent_action_message?: string | null
+  central_agent_version?: string | null
   created_at: string | null
   updated_at: string | null
   system_info?: {
diff --git a/server/api/servers.py b/server/api/servers.py
index 278a5ef1..c7d9e7f5 100644
--- a/server/api/servers.py
+++ b/server/api/servers.py
@@ -63,8 +63,21 @@ async def _schedule_server_onboarding(server_ids: list[int], operator: str) -> i
 
 
 def _server_has_agent_monitoring(server: Server) -> bool:
-    """True when this server is expected to run Nexus Agent (key or version on file)."""
-    return bool((server.agent_api_key or "").strip() or (server.agent_version or "").strip())
+    """True when Agent has actually reported in (version/heartbeat), not key-only."""
+    from server.utils.agent_version import agent_is_installed
+
+    return agent_is_installed(agent_version_db=server.agent_version, heartbeat=None)
+
+
+def _apply_agent_guidance(server_data: dict, server: Server, heartbeat: dict | None) -> None:
+    from server.utils.agent_version import compute_agent_guidance
+
+    server_data.update(
+        compute_agent_guidance(
+            agent_version_db=server.agent_version,
+            heartbeat=heartbeat,
+        )
+    )
 
 # ── CRUD ──
 
@@ -2123,7 +2136,9 @@ def _derive_server_status(is_online: bool | None, agent_version: str | None, *,
 
 def _apply_heartbeat_overlay(server_data: dict, server: Server, heartbeat: dict | None) -> None:
     """Overlay Redis heartbeat onto server_data and refresh derived status."""
-    has_agent = _server_has_agent_monitoring(server)
+    from server.utils.agent_version import agent_is_installed
+
+    installed = agent_is_installed(agent_version_db=server.agent_version, heartbeat=heartbeat)
     if heartbeat:
         server_data["is_online"] = heartbeat.get("is_online") == "True"
         if heartbeat.get("system_info"):
@@ -2143,21 +2158,22 @@ def _apply_heartbeat_overlay(server_data: dict, server: Server, heartbeat: dict
             server_data["time_drift_seconds"] = 0.0
         server_data["drift_level"] = heartbeat.get("drift_level", "ok")
         server_data["_source"] = "redis"
-    elif has_agent:
+    elif installed:
         server_data["is_online"] = False
         server_data["_source"] = "redis_miss"
     server_data["status"] = _derive_server_status(
         server_data.get("is_online"),
         server_data.get("agent_version") or server.agent_version,
-        has_agent=has_agent,
+        has_agent=installed,
     )
+    _apply_agent_guidance(server_data, server, heartbeat)
 
 
 def _server_to_dict(server: Server) -> dict:
     """Convert Server model to API response dict (hide sensitive fields)"""
     from server.utils.files_elevation import get_files_elevation
 
-    return {
+    data = {
         "id": server.id,
         "name": server.name,
         "domain": server.domain,
@@ -2196,6 +2212,8 @@ def _server_to_dict(server: Server) -> dict:
         "created_at": str(server.created_at) if server.created_at else None,
         "updated_at": str(server.updated_at) if server.updated_at else None,
     }
+    _apply_agent_guidance(data, server, None)
+    return data
 
 
 def _sync_log_to_dict(log, server_name: str = None) -> dict:
diff --git a/server/utils/agent_version.py b/server/utils/agent_version.py
index bba32c66..dddee1a2 100644
--- a/server/utils/agent_version.py
+++ b/server/utils/agent_version.py
@@ -54,3 +54,71 @@ def is_version_at_least(remote: str, central: str) -> bool:
     if not central_t:
         return bool(remote_t)
     return remote_t >= central_t
+
+
+def agent_is_installed(
+    *,
+    agent_version_db: str | None,
+    heartbeat: dict[str, str] | None = None,
+) -> bool:
+    """True when Agent has reported a version or heartbeat (not merely a DB API key)."""
+    if heartbeat:
+        if (heartbeat.get("agent_version") or "").strip():
+            return True
+        if heartbeat.get("last_heartbeat"):
+            return True
+    return bool((agent_version_db or "").strip())
+
+
+def compute_agent_guidance(
+    *,
+    agent_version_db: str | None,
+    heartbeat: dict[str, str] | None = None,
+    central: str | None = None,
+) -> dict[str, str | None]:
+    """UI hints: install / upgrade / offline / ok."""
+    central_v = central or get_central_agent_version()
+    live_ver = ""
+    if heartbeat:
+        live_ver = (heartbeat.get("agent_version") or "").strip()
+    if not live_ver:
+        live_ver = (agent_version_db or "").strip()
+
+    has_heartbeat = bool(heartbeat and heartbeat.get("last_heartbeat"))
+    installed = agent_is_installed(agent_version_db=agent_version_db, heartbeat=heartbeat)
+
+    base: dict[str, str | None] = {
+        "central_agent_version": central_v,
+        "agent_action": "ok",
+        "agent_action_message": None,
+    }
+
+    if not installed:
+        return {
+            **base,
+            "agent_action": "install",
+            "agent_action_message": (
+                f"尚未安装 Agent（主站版本 {central_v}）。"
+                "安装后可自动上报 CPU/内存/磁盘与在线状态；未安装时仅能通过 SSH 手动探活。"
+            ),
+        }
+
+    if live_ver and is_version_lower(live_ver, central_v):
+        return {
+            **base,
+            "agent_action": "upgrade",
+            "agent_action_message": (
+                f"当前 Agent {live_ver}，低于主站 {central_v}，建议升级以获取最新心跳与探针能力。"
+            ),
+        }
+
+    if not has_heartbeat:
+        return {
+            **base,
+            "agent_action": "offline",
+            "agent_action_message": (
+                "Agent 已登记但暂无心跳，请检查子机 nexus-agent 服务或点击「诊断」。"
+            ),
+        }
+
+    return base
diff --git a/tests/test_agent_version.py b/tests/test_agent_version.py
index 236aed13..2b4af2a9 100644
--- a/tests/test_agent_version.py
+++ b/tests/test_agent_version.py
@@ -7,6 +7,8 @@ import pytest
 from server.application.server_batch_common import agent_install_skip_result
 from server.domain.models import Server
 from server.utils.agent_version import (
+    agent_is_installed,
+    compute_agent_guidance,
     get_central_agent_version,
     is_version_at_least,
     is_version_lower,
@@ -36,6 +38,40 @@ def test_central_agent_version_matches_agent_py():
     assert get_central_agent_version() == "2.0.0"
 
 
+def test_agent_is_installed():
+    assert agent_is_installed(agent_version_db=None, heartbeat=None) is False
+    assert agent_is_installed(agent_version_db="2.0.0", heartbeat=None) is True
+    assert agent_is_installed(
+        agent_version_db=None,
+        heartbeat={"agent_version": "2.0.0", "last_heartbeat": "2026-01-01"},
+    ) is True
+    assert agent_is_installed(agent_version_db=None, heartbeat={"last_heartbeat": "x"}) is True
+
+
+def test_compute_agent_guidance_install():
+    g = compute_agent_guidance(agent_version_db=None, heartbeat=None, central="2.0.0")
+    assert g["agent_action"] == "install"
+    assert "尚未安装" in (g["agent_action_message"] or "")
+
+
+def test_compute_agent_guidance_upgrade():
+    g = compute_agent_guidance(
+        agent_version_db="1.0.0",
+        heartbeat={"agent_version": "1.0.0", "last_heartbeat": "t"},
+        central="2.0.0",
+    )
+    assert g["agent_action"] == "upgrade"
+
+
+def test_compute_agent_guidance_ok():
+    g = compute_agent_guidance(
+        agent_version_db="2.0.0",
+        heartbeat={"agent_version": "2.0.0", "last_heartbeat": "t", "is_online": "True"},
+        central="2.0.0",
+    )
+    assert g["agent_action"] == "ok"
+
+
 @pytest.mark.asyncio
 async def test_agent_install_skip_when_version_current():
     server = Server(id=1, name="A", agent_api_key="nxs-k", agent_version="2.0.0")