diff --git a/CHANGELOG.md b/CHANGELOG.md
index 5d39d0e..e200b1b 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -24,6 +24,7 @@
 
 ### Added
 
+- Added per-source sync difference previews, retry for individual failed jobs, and owner-only batch retry of failed jobs.
 - Added optional per-source attachment archive age: cached files are replaced with their original remote links after the configured period.
 - Added opt-in Discord/ntfy alerts for exhausted sync retries and stale signed webhooks, with per-event rate limiting.
 - Added safe signed Memos webhook rotation: create the replacement first, then remove the previous remote webhook before committing the new credentials.
diff --git a/app/api/sources/[id]/manage/route.ts b/app/api/sources/[id]/manage/route.ts
index d0cefb5..dc6fac1 100644
--- a/app/api/sources/[id]/manage/route.ts
+++ b/app/api/sources/[id]/manage/route.ts
@@ -38,6 +38,8 @@ export async function POST(req: Request, { params }: { params: Promise<{ id: str
         const name = identity.displayName || identity.nickname || identity.username || identity.name;
         db.prepare("UPDATE sources SET name=?,last_connection_at=CURRENT_TIMESTAMP,last_connection_error=NULL,remote_display_name=?,remote_avatar_url=? WHERE id=?").run(name, name, avatarUrl, id);
       } catch (connectionError) { const message = connectionError instanceof Error ? connectionError.message : "Connection failed"; db.prepare("UPDATE sources SET last_connection_error=? WHERE id=?").run(message, id); throw connectionError; }
+    } else if (action === "retry-failed-jobs") {
+      if (!owner) throw new Error("Only the owner can retry all failed jobs"); db.prepare("UPDATE sync_jobs SET status='queued',attempts=0,last_error=NULL,started_at=NULL,finished_at=NULL,run_after=CURRENT_TIMESTAMP WHERE source_id=? AND status='failed'").run(id);
     } else if (action === "leave") {
       if (owner) throw new Error("Transfer ownership or delete the source before leaving");
       db.prepare("DELETE FROM source_members WHERE source_id=? AND user_id=?").run(id, user.id);
diff --git a/app/api/sources/[id]/preview/route.ts b/app/api/sources/[id]/preview/route.ts
new file mode 100644
index 0000000..a7fd88b
--- /dev/null
+++ b/app/api/sources/[id]/preview/route.ts
@@ -0,0 +1,6 @@
+import { NextResponse } from "next/server";
+import { requireUser } from "@/lib/auth";
+import { decrypt } from "@/lib/crypto";
+import { db } from "@/lib/db";
+import { getMemosIdentity, listMemos } from "@/lib/memos";
+export async function GET(_request: Request, { params }: { params: Promise<{ id: string }> }) { try { const user = await requireUser(); const { id: rawId } = await params; const id = Number(rawId); const source = db.prepare("SELECT s.* FROM sources s JOIN source_members sm ON sm.source_id=s.id WHERE s.id=? AND sm.user_id=? AND s.integration_type='memos'").get(id, user.id) as any; if (!source) return NextResponse.json({ error: "Not found" }, { status: 404 }); const token = decrypt(source.token_encrypted); const identity = await getMemosIdentity(source.base_url, token); const rules = { creator: identity.name, tags: JSON.parse(source.sync_tags_json || "[]"), from: source.sync_from, to: source.sync_to, attachmentMode: source.sync_attachment_mode }; const remote = await listMemos(source.base_url, token, rules, { pageSize: 100 }); const local = new Set((db.prepare("SELECT remote_memo_name FROM posts WHERE source_id=? AND origin='memos'").all(id) as { remote_memo_name: string }[]).map((row) => row.remote_memo_name)); const added = remote.memos.filter((memo) => !local.has(memo.name)).length; return NextResponse.json({ inspected: remote.memos.length, added, existing: remote.memos.length - added, hasMore: Boolean(remote.nextPageToken) }); } catch (error) { return NextResponse.json({ error: error instanceof Error ? error.message : "preview" }, { status: 400 }); } }
diff --git a/app/api/sync/jobs/[id]/retry/route.ts b/app/api/sync/jobs/[id]/retry/route.ts
new file mode 100644
index 0000000..bcf1a02
--- /dev/null
+++ b/app/api/sync/jobs/[id]/retry/route.ts
@@ -0,0 +1,6 @@
+import { NextResponse } from "next/server";
+import { requireUser } from "@/lib/auth";
+import { db } from "@/lib/db";
+import { externalUrl } from "@/lib/http";
+import { requireSameOrigin } from "@/lib/security";
+export async function POST(request: Request, { params }: { params: Promise<{ id: string }> }) { try { requireSameOrigin(request); const user = await requireUser(); const { id: rawId } = await params; const id = Number(rawId); const job = db.prepare("SELECT j.id FROM sync_jobs j JOIN source_members sm ON sm.source_id=j.source_id WHERE j.id=? AND sm.user_id=? AND j.status='failed'").get(id, user.id); if (!job) throw new Error("Failed job not found"); db.prepare("UPDATE sync_jobs SET status='queued',attempts=0,last_error=NULL,started_at=NULL,finished_at=NULL,run_after=CURRENT_TIMESTAMP WHERE id=?").run(id); return NextResponse.redirect(externalUrl(request, "/dashboard?sync=queued")); } catch (error) { return NextResponse.redirect(externalUrl(request, "/dashboard?error=" + encodeURIComponent(error instanceof Error ? error.message : "retry"))); } }
diff --git a/app/dashboard/page.tsx b/app/dashboard/page.tsx
index 8af3e12..c1d7e9d 100644
--- a/app/dashboard/page.tsx
+++ b/app/dashboard/page.tsx
@@ -4,6 +4,7 @@ import { db } from "@/lib/db";
 import { PublishForm } from "./publish-form";
 import { WebhookControl } from "./webhook-control";
 import { InviteControl } from "./invite-control";
+import { SyncPreview } from "./sync-preview";
 
 type Source = { id: number; name: string; base_url: string; integration_type: "memos" | "rss"; rss_feed_url: string | null; sync_status: string; last_synced_at: string | null; last_error: string | null; webhook_secret_hash: string | null; webhook_mode: string; last_webhook_at: string | null; owner_id: number; membership_role: "owner" | "editor" | "viewer"; is_enabled: number; disabled_at: string | null; sync_tags_json: string; sync_from: string | null; sync_to: string | null; sync_attachment_mode: "all" | "images" | "none"; sync_batch_size: number; sync_max_posts: number | null; sync_cursor: string | null; sync_imported_count: number; attachment_storage_mode: "remote" | "images" | "all"; attachment_cache_limit_bytes: number; attachment_archive_after_days: number | null; attachment_cache_error: string | null; remote_display_name: string | null; remote_avatar_url: string | null; last_connection_at: string | null; last_connection_error: string | null };
 type Job = { id: number; kind: string; trigger: string | null; status: string; attempts: number; last_error: string | null; created_at: string; finished_at: string | null };
@@ -28,12 +29,14 @@ export default async function Dashboard({ searchParams }: { searchParams: Promis
       <p className="meta">來源 ID：{source.id}<br />{source.integration_type === "rss" ? source.rss_feed_url : source.base_url}{source.remote_display_name && <><br />Memos 帳號：{source.remote_avatar_url && <img className="avatar" src={source.remote_avatar_url} alt="" />} {source.remote_display_name}</>}<br />成員：{source.members.map((member) => `${member.username}${member.role === "owner" ? "（建立者）" : ""}`).join("、")}<br />上次同步：{source.last_synced_at || "尚未完成"}{source.sync_cursor && <>（批次匯入中：{source.sync_imported_count} 篇）</>}<br />{source.integration_type === "memos" && <>附件保存：{source.attachment_storage_mode === "remote" ? "遠端連結" : source.attachment_storage_mode === "images" ? "只快取圖片" : "完整備份"}（配額 {Math.round(source.attachment_cache_limit_bytes / 1024 / 1024)} MiB）<br />連線：{source.last_connection_at ? `最近成功：${new Date(source.last_connection_at + "Z").toLocaleString("zh-TW")}` : "尚未測試"}<br />Webhook：{source.webhook_secret_hash ? (source.last_webhook_at ? (Date.now() - new Date(source.last_webhook_at + "Z").getTime() > 7 * 24 * 60 * 60 * 1000 ? `警示：超過 7 天未收到（最近：${new Date(source.last_webhook_at + "Z").toLocaleString("zh-TW")}）` : `健康（最近收到：${new Date(source.last_webhook_at + "Z").toLocaleString("zh-TW")}）`) : "已建立 URL，尚未收到呼叫") : "尚未建立 URL"}</>}{!source.is_enabled && <><br />已停用：{source.disabled_at ? new Date(source.disabled_at + "Z").toLocaleString("zh-TW") : "是"}</>}{source.last_error && <><br /><span className="error">同步：{source.last_error}</span></>}{source.last_connection_error && <><br /><span className="error">連線：{source.last_connection_error}</span></>}{source.attachment_cache_error && <><br /><span className="error">附件快取：{source.attachment_cache_error}</span></>}</p>
       {source.owner_id === user.id ? <>
         {source.integration_type === "memos" && <WebhookControl sourceId={source.id} configured={Boolean(source.webhook_secret_hash)} automatic={source.webhook_mode === "signed"} />}
+        {source.integration_type === "memos" && <SyncPreview sourceId={source.id} />}
         <InviteControl sourceId={source.id} />
+        <form action={`/api/sources/${source.id}/manage`} method="post"><input type="hidden" name="action" value="retry-failed-jobs" /><button>批次重試失敗同步</button></form>
         <form action={`/api/sources/${source.id}/manage`} method="post"><input type="hidden" name="action" value="set-attachment-storage" /><label>附件保存策略<select name="mode" defaultValue={source.attachment_storage_mode}><option value="remote">遠端連結（不佔 Hub 空間）</option><option value="images">只快取圖片</option><option value="all">完整備份附件</option></select></label><label>快取配額（MiB）<input name="quotaMiB" type="number" min="10" max="10240" defaultValue={Math.round(source.attachment_cache_limit_bytes / 1024 / 1024)} /></label><label>快取封存天數（0 為不封存）<input name="archiveAfterDays" type="number" min="0" max="3650" defaultValue={source.attachment_archive_after_days || 0} /></label><button>儲存附件策略並同步</button></form>
         <details><summary>來源管理</summary><form action={`/api/sources/${source.id}/manage`} method="post"><input type="hidden" name="action" value="rename" /><label>顯示名稱<input name="name" defaultValue={source.name} required maxLength={80} /></label><button>儲存名稱</button></form><form action={`/api/sources/${source.id}/manage`} method="post"><input type="hidden" name="action" value="set-sync-rules" /><label>只同步標籤（逗號分隔，留白為全部）<input name="tags" defaultValue={source.syncTags.join(", ")} placeholder="旅行, 技術" /></label><div className="row"><label>開始日期<input name="from" type="date" defaultValue={source.sync_from || ""} /></label><label>結束日期<input name="to" type="date" defaultValue={source.sync_to || ""} /></label></div><label>附件<select name="attachmentMode" defaultValue={source.sync_attachment_mode}><option value="all">同步全部附件</option><option value="images">僅同步圖片</option><option value="none">不同步附件</option></select></label><div className="row"><label>每批貼文數<input name="batchSize" type="number" min="10" max="100" defaultValue={source.sync_batch_size} /></label><label>首次匯入上限（0 為不限）<input name="maxPosts" type="number" min="0" max="100000" defaultValue={source.sync_max_posts || 0} /></label></div><button>儲存同步規則並從頭批次同步</button></form><form action={`/api/sources/${source.id}/manage`} method="post"><input type="hidden" name="action" value="test-connection" /><button>測試 Memos 連線</button></form><form action={`/api/sources/${source.id}/manage`} method="post"><input type="hidden" name="action" value="set-enabled" /><input type="hidden" name="enabled" value={source.is_enabled ? "0" : "1"} /><button className={source.is_enabled ? "danger" : ""}>{source.is_enabled ? "停用來源" : "啟用來源"}</button></form>{source.members.length > 1 && <form action={`/api/sources/${source.id}/manage`} method="post"><input type="hidden" name="action" value="transfer" /><label>轉移建立者<select name="username" required defaultValue=""> <option value="" disabled>選擇成員</option>{source.members.filter((member) => member.id !== user.id).map((member) => <option key={member.id} value={member.username}>{member.username}</option>)}</select></label><button>轉移所有權</button></form>}<form action={`/api/sources/${source.id}/manage`} method="post"><input type="hidden" name="action" value="delete" /><button className="danger">刪除來源與遠端鏡像貼文</button></form></details>
       </> : <form action={`/api/sources/${source.id}/manage`} method="post"><input type="hidden" name="action" value="leave" /><button className="danger">離開共享來源</button></form>}
       <form action="/api/sync" method="post"><input type="hidden" name="sourceId" value={source.id} /><button disabled={!source.is_enabled}>{source.is_enabled ? "立即同步" : "來源已停用"}</button></form>
-      <details><summary>最近同步工作</summary>{source.jobs.length ? <ul className="job-list">{source.jobs.map((job) => <li key={job.id}><strong>{job.kind}</strong> · {job.trigger || "legacy"} · <span className="tag">{job.status}</span> · 嘗試 {job.attempts} 次<br /><span className="meta">建立：{new Date(job.created_at + "Z").toLocaleString("zh-TW")}{job.finished_at && `；完成：${new Date(job.finished_at + "Z").toLocaleString("zh-TW")}`}</span>{job.last_error && <><br /><span className="error">{job.last_error}</span></>}</li>)}</ul> : <p className="muted">尚無同步工作。</p>}</details>
+      <details><summary>最近同步工作</summary>{source.jobs.length ? <ul className="job-list">{source.jobs.map((job) => <li key={job.id}><strong>{job.kind}</strong> · {job.trigger || "legacy"} · <span className="tag">{job.status}</span> · 嘗試 {job.attempts} 次<br /><span className="meta">建立：{new Date(job.created_at + "Z").toLocaleString("zh-TW")}{job.finished_at && `；完成：${new Date(job.finished_at + "Z").toLocaleString("zh-TW")}`}</span>{job.last_error && <><br /><span className="error">{job.last_error}</span></>}{job.status === "failed" && <form action={`/api/sync/jobs/${job.id}/retry`} method="post"><button>重試此工作</button></form>}</li>)}</ul> : <p className="muted">尚無同步工作。</p>}</details>
     </article>)}</section>
   </>;
 }
diff --git a/app/dashboard/sync-preview.tsx b/app/dashboard/sync-preview.tsx
new file mode 100644
index 0000000..f3f12ae
--- /dev/null
+++ b/app/dashboard/sync-preview.tsx
@@ -0,0 +1,3 @@
+"use client";
+import { useState } from "react";
+export function SyncPreview({ sourceId }: { sourceId: number }) { const [text, setText] = useState(""); async function preview() { setText("讀取中…"); const response = await fetch(`/api/sources/${sourceId}/preview`); const body = await response.json(); setText(response.ok ? `本頁預覽：新增 ${body.added}、已存在 ${body.existing}，共檢查 ${body.inspected} 篇${body.hasMore ? "（來源尚有更多頁）" : ""}` : body.error || "無法預覽"); } return <div><button type="button" onClick={preview}>預覽同步差異</button>{text && <p className="meta">{text}</p>}</div>; }