diff --git a/backend/app/api/knowledge.py b/backend/app/api/knowledge.py
index 3911abfc..b5dd711c 100644
--- a/backend/app/api/knowledge.py
+++ b/backend/app/api/knowledge.py
@@ -2,11 +2,14 @@ from __future__ import annotations
 
 from typing import Any
 
-from fastapi import APIRouter, Depends, File, HTTPException, Query, UploadFile
+from fastapi import (
+    APIRouter, BackgroundTasks, Depends, File, HTTPException, Query, UploadFile,
+)
 from pydantic import BaseModel, Field
 from sqlalchemy import select
 from sqlalchemy.ext.asyncio import AsyncSession
 
+from app.core.config import settings
 from app.db.base import get_session
 from app.db.models import Document, MemoryItem, Skill
 from app.memory import inverted, kb, store
@@ -105,6 +108,10 @@ class DocumentOut(BaseModel):
     source: str
     mime: str
     chunk_count: int
+    #: ready | processing | failed。前端据此显示"处理中 3200/7914 段"
+    status: str = "ready"
+    error: str = ""
+    meta: dict[str, Any] = Field(default_factory=dict)
     created_at: Any = None
 
     model_config = {"from_attributes": True}
@@ -146,13 +153,23 @@ async def ingest(payload: IngestIn, session: AsyncSession = Depends(get_session)
 
 @kb_router.post("/upload", response_model=DocumentOut, status_code=201)
 async def upload(
+    background: BackgroundTasks,
     file: UploadFile = File(...),
     collection: str = "default",
     session: AsyncSession = Depends(get_session),
 ) -> Document:
-    raw = await file.read()
-    if len(raw) > 10 * 1024 * 1024:
-        raise HTTPException(413, "文件超过 10MB")
+    # 边读边数，超了立刻停——原来是 raw = await file.read() 读完再判断，
+    # 传个 1GB 的文件，内存在报 413 之前就已经吃掉了。那个检查拦的是"入库"，
+    # 不是"占内存"
+    limit = settings.max_upload_mb * 1024 * 1024
+    chunks: list[bytes] = []
+    total = 0
+    while piece := await file.read(1024 * 1024):
+        total += len(piece)
+        if total > limit:
+            raise HTTPException(413, f"文件超过 {settings.max_upload_mb}MB")
+        chunks.append(piece)
+    raw = b"".join(chunks)
 
     from app.memory.parsing import UnsupportedDocument, extract
 
@@ -161,14 +178,41 @@ async def upload(
     except UnsupportedDocument as e:
         # 原样交回：里面写的是"装哪个包"或"这是扫描件"，都能照着做
         raise HTTPException(415, str(e)) from None
-    return await kb.ingest_document(
+    doc = await kb.create_document(
         session,
         collection=collection,
         title=file.filename or "上传文档",
         content=content,
         source=file.filename or "",
         mime=file.content_type or "text/plain",
+        status="processing",
     )
+    # 立刻返回，切块和算向量在后台跑。实测一个 10MB 文档用本地哈希要两分半，
+    # 换成远端 embedding 是几十分钟——压在请求里必然超时，而后端其实还在跑，
+    # 界面显示失败、数据其实成功，比直接拒绝还糟
+    background.add_task(_process_in_background, doc.id)
+    return doc
+
+
+async def _process_in_background(doc_id: str) -> None:
+    """后台切块。进度写回文档行，失败也写回——不然它会永远停在"处理中"。"""
+    from app.db.base import SessionLocal
+
+    async with SessionLocal() as session:
+        doc = await session.get(Document, doc_id)
+        if not doc:
+            return
+        try:
+            # 进度由 process_document 自己按批提交——它就在主事务里，
+            # 不会和另一个 session 抢 SQLite 的写锁
+            await kb.process_document(session, doc)
+        except Exception as e:  # noqa: BLE001
+            await session.rollback()
+            doc = await session.get(Document, doc_id)
+            if doc:
+                doc.status = "failed"
+                doc.error = f"{type(e).__name__}: {e}"[:500]
+                await session.commit()
 
 
 @kb_router.get("/search")
diff --git a/backend/app/core/config.py b/backend/app/core/config.py
index 781c89be..bbfdb269 100644
--- a/backend/app/core/config.py
+++ b/backend/app/core/config.py
@@ -66,6 +66,9 @@ class Settings(BaseSettings):
     max_run_seconds: int = 600
     max_graph_steps: int = 200
     max_agent_steps: int = 25
+    #: 上传文件的大小上限（MB）。原来写死 10，而且是读完整个文件才检查——
+    #: 传一个 1GB 的文件，内存在报 413 之前就吃掉了
+    max_upload_mb: int = 50
     max_concurrent_runs: int = 20
 
     # --- 工具 ---
diff --git a/backend/app/db/base.py b/backend/app/db/base.py
index 83e5d130..81d1ab80 100644
--- a/backend/app/db/base.py
+++ b/backend/app/db/base.py
@@ -82,6 +82,8 @@ _COLUMN_MIGRATIONS: list[tuple[str, str, str]] = [
     ("memories", "embed_model", "VARCHAR(100) DEFAULT ''"),
     ("memories", "embed_dim", "INTEGER DEFAULT 0"),
     ("chunks", "token_len", "INTEGER DEFAULT 0"),
+    ("documents", "status", "TEXT DEFAULT 'ready'"),
+    ("documents", "error", "TEXT DEFAULT ''"),
 ]
 
 
diff --git a/backend/app/db/models.py b/backend/app/db/models.py
index 7529327b..e6616aa2 100644
--- a/backend/app/db/models.py
+++ b/backend/app/db/models.py
@@ -279,6 +279,11 @@ class Document(Base, TimestampMixin):
     content: Mapped[str] = mapped_column(Text, default="")
     meta: Mapped[dict[str, Any]] = mapped_column(default=dict)
     chunk_count: Mapped[int] = mapped_column(Integer, default=0)
+    # 切块+算向量是在后台跑的：一个 10MB 文档配上远端 embedding 要几十分钟，
+    # 压在 HTTP 请求里必然超时——而后端其实还在跑，界面显示失败、数据其实成功，
+    # 比直接拒绝还糟。ready | processing | failed
+    status: Mapped[str] = mapped_column(String(20), default="ready")
+    error: Mapped[str] = mapped_column(Text, default="")
 
     chunks: Mapped[list["Chunk"]] = relationship(
         back_populates="document", cascade="all, delete-orphan"
diff --git a/backend/app/main.py b/backend/app/main.py
index b5a8e3b3..5fe5b524 100644
--- a/backend/app/main.py
+++ b/backend/app/main.py
@@ -43,6 +43,19 @@ async def lifespan(_: FastAPI) -> AsyncIterator[None]:
         except Exception as e:  # noqa: BLE001 - key 没了不该拦住整个服务起不来
             logger.warning("embedding 配置没能生效，暂用本地向量：%s", e)
 
+    # 上次被强杀时留下的"处理中"文档。后台任务不会自己回来，留着它只会在
+    # 界面上永远转圈——和 runner 对 running 的 run 是同一个道理
+    from sqlalchemy import update as _update
+
+    from app.db.models import Document as _Doc
+
+    async with SessionLocal() as _s:
+        await _s.execute(
+            _update(_Doc).where(_Doc.status == "processing")
+            .values(status="failed", error="服务重启，这份文档没有处理完，请重新上传")
+        )
+        await _s.commit()
+
     await run_manager.setup()
     from app.sandbox.manager import sandbox_manager as _sbm
 
diff --git a/backend/app/memory/kb.py b/backend/app/memory/kb.py
index 4f3ed72b..77d4d5e5 100644
--- a/backend/app/memory/kb.py
+++ b/backend/app/memory/kb.py
@@ -15,6 +15,9 @@ from app.memory.embeddings import (
 
 _TARGET = 800
 _OVERLAP = 120
+#: 每批送多少段去算向量。远端接口单次批量有上限（OpenAI 是 2048），而且
+#: 一次把上万段全发出去，要么超时要么被限流，中途失败还没有断点
+_EMBED_BATCH = 64
 
 
 def chunk_text(text: str, target: int = _TARGET, overlap: int = _OVERLAP) -> list[str]:
@@ -119,7 +122,32 @@ async def ingest_document(
     source: str = "",
     mime: str = "text/plain",
     meta: dict[str, Any] | None = None,
+    on_progress: Any = None,
 ) -> Document:
+    doc = await create_document(
+        session, collection=collection, title=title, content=content,
+        source=source, mime=mime, meta=meta, status="ready",
+    )
+    await process_document(session, doc, on_progress=on_progress)
+    return doc
+
+
+async def create_document(
+    session: AsyncSession,
+    *,
+    collection: str,
+    title: str,
+    content: str,
+    source: str = "",
+    mime: str = "text/plain",
+    meta: dict[str, Any] | None = None,
+    status: str = "ready",
+) -> Document:
+    """只建文档行，不切块不算向量。
+
+    拆出来是为了让上传能立刻返回：切块 + 算向量在后台跑，一个 10MB 文档配上
+    远端 embedding 要几十分钟，压在 HTTP 请求里必然超时。
+    """
     doc = Document(
         collection=collection,
         title=title or source or "未命名文档",
@@ -127,32 +155,66 @@ async def ingest_document(
         mime=mime,
         content=content,
         meta=meta or {},
+        status=status,
     )
     session.add(doc)
-    await session.flush()
+    await session.commit()
+    await session.refresh(doc)
+    return doc
 
+
+async def process_document(
+    session: AsyncSession, doc: Document, *, on_progress: Any = None
+) -> Document:
+    """切块、算向量、建倒排。可以对着一个已存在的文档行反复跑（会先清掉旧的）。"""
+    from sqlalchemy import delete as sa_delete
+
+    old_ids = list((await session.execute(
+        select(Chunk.id).where(Chunk.document_id == doc.id))).scalars())
+    if old_ids:
+        await inverted.drop_chunk_terms(session, old_ids)
+        await session.execute(sa_delete(Chunk).where(Chunk.document_id == doc.id))
+
+    collection, content = doc.collection, doc.content
     pieces = chunk_text(content)
-    made: list[Chunk] = []
-    if pieces:
-        vectors = await embed_texts(pieces)
-        for i, (piece, vec) in enumerate(zip(pieces, vectors)):
+    model_id, dim = embedder_id(), embedder_dim()
+
+    # 一批算完就落盘。分批本身是必须的——原来 embed_texts(pieces) 一次全发，
+    # 本地哈希只是慢，换成远端模型就是必挂（一个 10MB 文档近八千段，塞不下）。
+    #
+    # 每批都 commit 还有第二个好处：进度能被别人看见。试过用另一个 session
+    # 单独写进度，但 SQLite 只允许一个写者，主事务开着的时候那次写会被堵住，
+    # 界面上整个过程都是空的、只在结束时闪一下。
+    for i in range(0, len(pieces), _EMBED_BATCH):
+        part = pieces[i:i + _EMBED_BATCH]
+        vectors = await embed_texts(part)
+        made: list[Chunk] = []
+        for offset, (piece, vec) in enumerate(zip(part, vectors)):
             chunk = Chunk(
                 document_id=doc.id,
                 collection=collection,
-                ordinal=i,
+                ordinal=i + offset,
                 content=piece,
                 embedding=to_blob(vec),
-                embed_model=embedder_id(),
-                embed_dim=embedder_dim(),
+                embed_model=model_id,
+                embed_dim=dim,
                 meta={"title": doc.title},
             )
             session.add(chunk)
             made.append(chunk)
-        # 先 flush 拿到 chunk.id，倒排行要引用它
-        await session.flush()
+        await session.flush()          # 先拿到 chunk.id，倒排行要引用它
         for chunk in made:
             await inverted.index_chunk(session, chunk)
+
+        done = min(i + _EMBED_BATCH, len(pieces))
+        doc.meta = {**(doc.meta or {}), "progress": {"done": done, "total": len(pieces)}}
+        await session.commit()
+        if on_progress:
+            on_progress(done, len(pieces))
+
     doc.chunk_count = len(pieces)
+    doc.status = "ready"
+    doc.error = ""
     await session.commit()
     await session.refresh(doc)
     return doc
@@ -278,7 +340,7 @@ async def reindex(session: AsyncSession, collection: str | None = None) -> dict[
         return {"collection": collection, "reindexed": 0, "embedder": embedder_id()}
 
     model_id, dim = embedder_id(), embedder_dim()
-    batch = 64
+    batch = _EMBED_BATCH
     for i in range(0, len(rows), batch):
         part = rows[i:i + batch]
         vectors = await embed_texts([r.content for r in part])
diff --git a/backend/app/memory/store.py b/backend/app/memory/store.py
index 4a20ccde..30920e6a 100644
--- a/backend/app/memory/store.py
+++ b/backend/app/memory/store.py
@@ -210,7 +210,9 @@ async def reindex(session: AsyncSession, scope: str | None = None) -> int:
         return 0
 
     model_id, dim = embedder_id(), embedder_dim()
-    batch = 64   # 和 kb.reindex 一样按批：一次几千条全发给远端接口必被限流
+    from app.memory.kb import _EMBED_BATCH
+
+    batch = _EMBED_BATCH   # 和 kb 那边统一：一次几千条全发给远端接口必被限流
     for i in range(0, len(rows), batch):
         part = rows[i:i + batch]
         vectors = await embed_texts([r.content for r in part])
diff --git a/backend/tests/test_kb.py b/backend/tests/test_kb.py
index abaab43c..7cb67eb3 100644
--- a/backend/tests/test_kb.py
+++ b/backend/tests/test_kb.py
@@ -30,6 +30,17 @@ def _local_embedder():
     emb.configure("local")
 
 
+@pytest.fixture
+async def client():
+    from httpx import ASGITransport, AsyncClient
+
+    from app.main import app
+
+    transport = ASGITransport(app=app)
+    async with AsyncClient(transport=transport, base_url="http://test") as c:
+        yield c
+
+
 # --------------------------------------------------------------------------
 # 切块
 # --------------------------------------------------------------------------
@@ -588,3 +599,105 @@ async def test_the_endpoint_is_remembered_across_restarts(client=None) -> None:
     async with SessionLocal() as session:
         row = await session.get(Setting, e.EMBEDDING_SETTING_KEY)
     assert row is not None and "base_url" in row.value
+
+
+# --------------------------------------------------------------------------
+# 大文件：分批、后台、大小防护
+# --------------------------------------------------------------------------
+
+
+async def test_embedding_is_batched_not_one_giant_call(monkeypatch) -> None:
+    """原来是 embed_texts(pieces) 一次全发。
+
+    本地哈希只是慢，换成远端模型就是必挂：一个 10MB 文档切出近八千段，
+    远端接口单次批量有上限（OpenAI 是 2048），一次请求塞不下。
+    reindex 那边早就分批了，ingest 这条一直漏着。
+    """
+    from app.memory import kb as kb_mod
+
+    sizes: list[int] = []
+    real = kb_mod.embed_texts
+
+    async def spy(texts):
+        sizes.append(len(texts))
+        return await real(texts)
+
+    monkeypatch.setattr(kb_mod, "embed_texts", spy)
+
+    text = "\n\n".join(f"第{i}段内容，讲了一些东西。" * 12 for i in range(400))
+    async with SessionLocal() as session:
+        await kb.ingest_document(session, collection="batch_test", title="大文档", content=text)
+
+    assert len(sizes) > 1, f"只调了 {len(sizes)} 次，没有分批"
+    assert max(sizes) <= kb_mod._EMBED_BATCH, f"有一批 {max(sizes)} 条，超过了上限"
+
+
+async def test_progress_lands_in_the_db_while_it_runs() -> None:
+    """进度要能被别人看见。
+
+    试过用另一个 session 单独写，但 SQLite 只允许一个写者——主事务开着的时候
+    那次写会被堵住，整个过程界面上都是空的、只在结束时闪一下。改成主事务
+    自己按批提交。
+    """
+    from app.db.models import Document
+
+    seen: list[tuple[int, int]] = []
+    # 要切出多于一批（_EMBED_BATCH=64）的片段，否则只会有一次进度回调
+    text = "\n\n".join(f"第{i}段内容，这里要写得长一些才切得够多。" * 30 for i in range(300))
+
+    async with SessionLocal() as session:
+        doc = await kb.create_document(
+            session, collection="prog_test", title="进度", content=text, status="processing")
+        await kb.process_document(session, doc, on_progress=lambda d, t: seen.append((d, t)))
+
+    assert len(seen) > 1, "一次就跑完了，测不到进度"
+    assert seen[-1][0] == seen[-1][1], "最后一次进度不是满的"
+
+    # 关键：中途的进度确实落了库，不是只在内存里
+    async with SessionLocal() as session:
+        row = await session.get(Document, doc.id)
+    assert (row.meta or {}).get("progress", {}).get("total") == seen[-1][1]
+    assert row.status == "ready"
+
+
+async def test_a_failed_document_does_not_stay_processing_forever(client) -> None:
+    """失败了要写回 failed。不写的话它永远停在"处理中"，界面上一直转圈。"""
+    from app.db.models import Document
+    from app.api.knowledge import _process_in_background
+
+    async with SessionLocal() as session:
+        doc = await kb.create_document(
+            session, collection="fail_test", title="会失败的", content="一些内容",
+            status="processing")
+
+    import app.memory.kb as kb_mod
+
+    async def boom(*a, **kw):
+        raise RuntimeError("向量服务挂了")
+
+    orig = kb_mod.process_document
+    kb_mod.process_document = boom
+    try:
+        await _process_in_background(doc.id)
+    finally:
+        kb_mod.process_document = orig
+
+    async with SessionLocal() as session:
+        row = await session.get(Document, doc.id)
+    assert row.status == "failed"
+    assert "向量服务挂了" in row.error
+
+
+async def test_oversized_uploads_are_rejected_before_being_read(client) -> None:
+    """原来是 raw = await file.read() 读完再判断大小。
+
+    传个 1GB 的文件，内存在报 413 之前就已经吃掉了——那个检查拦的是"入库"，
+    不是"占内存"。
+    """
+    from app.core.config import settings
+
+    too_big = b"x" * ((settings.max_upload_mb + 1) * 1024 * 1024)
+    r = await client.post("/api/kb/upload", params={"collection": "big"},
+                          files={"file": ("big.txt", too_big, "text/plain")})
+    assert r.status_code == 413
+    assert str(settings.max_upload_mb) in r.json()["detail"]
diff --git a/frontend/src/pages/KnowledgePage.tsx b/frontend/src/pages/KnowledgePage.tsx
index 4b63f866..e38998a6 100644
--- a/frontend/src/pages/KnowledgePage.tsx
+++ b/frontend/src/pages/KnowledgePage.tsx
@@ -215,6 +215,14 @@ function KbTab() {
   }
   useEffect(() => { void load() }, [collection])
 
+  // 有文档还在切块就接着轮询。一个 10MB 文档配上远端 embedding 要几十分钟，
+  // 不轮询的话界面会一直停在"处理中"，人以为卡死了
+  useEffect(() => {
+    if (!docs.some((d) => d.status === 'processing')) return
+    const timer = setInterval(() => { void load() }, 2000)
+    return () => clearInterval(timer)
+  }, [docs, collection])
+
   const search = async () => {
     if (!query.trim()) { setHits(null); return }
     const res = await api.kb.search(query, collection, alpha)
@@ -310,8 +318,20 @@ function KbTab() {
         {docs.map((doc) => (
           <div key={doc.id} className="flex items-center gap-3 rounded-lg border bg-panel px-3 py-2">
             <div className="min-w-0 flex-1">
-              <div className="truncate text-[12px]">{doc.title}</div>
-              <div className="truncate text-[10.5px] text-faint">{doc.source} · {doc.chunk_count} 个片段</div>
+              <div className="flex items-center gap-1.5">
+                {doc.status === 'processing' && <Spinner size={11} />}
+                <span className="truncate text-[12px]">{doc.title}</span>
+              </div>
+              <div className="truncate text-[10.5px] text-faint">
+                {doc.status === 'processing'
+                  ? (doc.meta?.progress
+                      ? `正在切块并算向量… ${doc.meta.progress.done}/${doc.meta.progress.total} 段`
+                      : '正在切块并算向量…')
+                  : doc.status === 'failed'
+                    // 失败原因要写出来："这是扫描件"和"本地服务没起"是两件事
+                    ? <span style={{ color: 'var(--err)' }}>处理失败：{doc.error}</span>
+                    : `${doc.source} · ${doc.chunk_count} 个片段`}
+              </div>
             </div>
             <button className="btn btn-sm btn-ghost" onClick={async () => {
               if (!confirm(`删除「${doc.title}」？`)) return
diff --git a/frontend/src/types.ts b/frontend/src/types.ts
index 754f1eb6..e93569d9 100644
--- a/frontend/src/types.ts
+++ b/frontend/src/types.ts
@@ -136,6 +136,10 @@ export interface KbDocument {
   source: string
   mime: string
   chunk_count: number
+  /** ready | processing | failed。大文件的切块和算向量在后台跑 */
+  status?: string
+  error?: string
+  meta?: { progress?: { done: number; total: number } }
   created_at?: string
 }