diff --git a/common/data_source/rss_connector.py b/common/data_source/rss_connector.py
index 8000eaddfd..6fad756d73 100644
--- a/common/data_source/rss_connector.py
+++ b/common/data_source/rss_connector.py
@@ -10,14 +10,20 @@ import feedparser
 import requests
 
 from common.data_source.config import INDEX_BATCH_SIZE, REQUEST_TIMEOUT_SECONDS, DocumentSource
-from common.data_source.interfaces import LoadConnector, PollConnector
-from common.data_source.models import Document, GenerateDocumentsOutput, SecondsSinceUnixEpoch
+from common.data_source.interfaces import LoadConnector, PollConnector, SlimConnectorWithPermSync
+from common.data_source.models import (
+    Document,
+    GenerateDocumentsOutput,
+    GenerateSlimDocumentOutput,
+    SecondsSinceUnixEpoch,
+    SlimDocument,
+)
 from common.ssrf_guard import assert_url_is_safe, pin_dns as _pin_dns
 
 _MAX_REDIRECTS = 10
 
 
-class RSSConnector(LoadConnector, PollConnector):
+class RSSConnector(LoadConnector, PollConnector, SlimConnectorWithPermSync):
     def __init__(self, feed_url: str, batch_size: int = INDEX_BATCH_SIZE) -> None:
         self.feed_url = feed_url.strip()
         self.batch_size = batch_size
@@ -40,6 +46,25 @@ class RSSConnector(LoadConnector, PollConnector):
     def poll_source(self, start: SecondsSinceUnixEpoch, end: SecondsSinceUnixEpoch) -> GenerateDocumentsOutput:
         yield from self._load_entries(start=start, end=end)
 
+    def retrieve_all_slim_docs_perm_sync(
+        self,
+        callback: Any = None,
+    ) -> GenerateSlimDocumentOutput:
+        del callback
+
+        feed = self._read_feed(require_entries=False)
+        batch: list[SlimDocument] = []
+
+        for entry in feed.entries:
+            batch.append(SlimDocument(id=self._build_document_id(entry)))
+
+            if len(batch) >= self.batch_size:
+                yield batch
+                batch = []
+
+        if batch:
+            yield batch
+
     def _load_entries(
         self,
         start: SecondsSinceUnixEpoch | None = None,
@@ -130,7 +155,7 @@ class RSSConnector(LoadConnector, PollConnector):
     def _build_document(self, entry: Any, updated_at: datetime) -> Document:
         link = (entry.get("link") or "").strip()
         title = (entry.get("title") or "").strip()
-        stable_key = (entry.get("id") or link or title or self.feed_url).strip()
+        stable_key = self._resolve_stable_key(entry)
         semantic_identifier = title or link or stable_key
         content = self._build_content(entry, semantic_identifier)
         blob = content.encode("utf-8")
@@ -152,7 +177,7 @@ class RSSConnector(LoadConnector, PollConnector):
             metadata["categories"] = categories
 
         return Document(
-            id=f"rss:{hashlib.md5(stable_key.encode('utf-8')).hexdigest()}",
+            id=self._build_document_id(entry),
             source=DocumentSource.RSS,
             semantic_identifier=semantic_identifier,
             extension=".txt",
@@ -180,6 +205,15 @@ class RSSConnector(LoadConnector, PollConnector):
 
         return "\n\n".join(part for part in parts if part).strip()
 
+    def _build_document_id(self, entry: Any) -> str:
+        stable_key = self._resolve_stable_key(entry)
+        return f"rss:{hashlib.md5(stable_key.encode('utf-8')).hexdigest()}"
+
+    def _resolve_stable_key(self, entry: Any) -> str:
+        link = (entry.get("link") or "").strip()
+        title = (entry.get("title") or "").strip()
+        return (entry.get("id") or link or title or self.feed_url).strip()
+
     def _resolve_entry_time(self, entry: Any) -> datetime:
         for field in ("updated_parsed", "published_parsed"):
             value = entry.get(field)
diff --git a/rag/svr/sync_data_source.py b/rag/svr/sync_data_source.py
index 481d973d4e..1a516c2591 100644
--- a/rag/svr/sync_data_source.py
+++ b/rag/svr/sync_data_source.py
@@ -390,10 +390,30 @@ class RSS(SyncBase):
         if task["reindex"] == "1" or not task["poll_range_start"]:
             return self.connector.load_from_state()
 
-        return self.connector.poll_source(
+        end_time = datetime.now(timezone.utc).timestamp()
+        file_list = None
+        if self.conf.get("sync_deleted_files"):
+            logging.info(
+                "[RSS] Syncing deleted files via slim snapshot (connector_id=%s)",
+                task["connector_id"],
+            )
+            snapshot_start = time.perf_counter()
+            file_list = []
+            for slim_batch in self.connector.retrieve_all_slim_docs_perm_sync():
+                file_list.extend(slim_batch)
+            logging.info(
+                "[RSS] Slim snapshot fetched %d docs in %.2f seconds",
+                len(file_list),
+                time.perf_counter() - snapshot_start,
+            )
+
+        document_generator = self.connector.poll_source(
             task["poll_range_start"].timestamp(),
-            datetime.now(timezone.utc).timestamp(),
+            end_time,
         )
+        if file_list is not None:
+            return document_generator, file_list
+        return document_generator
 
 
 class Confluence(SyncBase):
diff --git a/web/src/pages/user-setting/data-source/constant/index.tsx b/web/src/pages/user-setting/data-source/constant/index.tsx
index 2371eb6f97..803d8ca9b8 100644
--- a/web/src/pages/user-setting/data-source/constant/index.tsx
+++ b/web/src/pages/user-setting/data-source/constant/index.tsx
@@ -117,6 +117,9 @@ export const DataSourceFeatureVisibilityMap: Partial<
   [DataSourceKey.ASANA]: {
     syncDeletedFiles: true,
   },
+  [DataSourceKey.RSS]: {
+    syncDeletedFiles: true,
+  },
 };
 
 const isDataSourceFeatureVisible = (