feat(backend): 无界列表端点加分页——projects/templates 支持 limit/offset

GET /projects 与 GET /templates 原一次返回全部 owner 行，行数随数据线性增长。
新增可复用分页依赖 ww_api.pagination.get_page（limit∈[1,200] 默认 50、offset≥0，
越界 → 422），两端点接入，Repository.list_for_owner 加 keyword-only limit/offset
把 LIMIT/OFFSET 下推 DB。向后兼容：不传参返回第一页。补 projects 分页 + 边界 422 测试。

apps/api/tests/fakes_projects.py

@@ -63,8 +63,13 @@ class FakeProjectRepo:
         self.rows[pid] = (owner_id, view)
         return view
 
-    async def list_for_owner(self, owner_id: uuid.UUID) -> list[ProjectView]:
-        return [v for (o, v) in self.rows.values() if o == owner_id]
+    async def list_for_owner(
+        self, owner_id: uuid.UUID, *, limit: int | None = None, offset: int = 0
+    ) -> list[ProjectView]:
+        views = [v for (o, v) in self.rows.values() if o == owner_id]
+        if limit is None:
+            return views
+        return views[offset : offset + limit]
 
     async def get(self, owner_id: uuid.UUID, project_id: uuid.UUID) -> ProjectView | None:
         entry = self.rows.get(project_id)

apps/api/tests/test_projects.py

@@ -222,6 +222,33 @@ async def test_list_projects() -> None:
     assert all(p["pending_review_count"] == 0 for p in projects)
 
 
+@pytest.mark.asyncio
+async def test_list_projects_paginates_with_limit_and_offset() -> None:
+    client, _, _, _ = _make_client()
+    async with client:
+        for t in ("甲", "乙", "丙"):
+            await client.post("/projects", json={"title": t})
+        page1 = await client.get("/projects?limit=2")
+        page2 = await client.get("/projects?limit=2&offset=2")
+    assert page1.status_code == 200
+    assert [p["title"] for p in page1.json()["projects"]] == ["甲", "乙"]
+    assert page2.status_code == 200
+    assert [p["title"] for p in page2.json()["projects"]] == ["丙"]
+
+
+@pytest.mark.asyncio
+async def test_list_projects_rejects_out_of_range_pagination() -> None:
+    client, _, _, _ = _make_client()
+    async with client:
+        too_small = await client.get("/projects?limit=0")
+        too_large = await client.get("/projects?limit=201")
+        neg_offset = await client.get("/projects?offset=-1")
+    # 边界越界 → FastAPI 422（limit∈[1,200]、offset≥0）。
+    assert too_small.status_code == 422
+    assert too_large.status_code == 422
+    assert neg_offset.status_code == 422
+
+
 @pytest.mark.asyncio
 async def test_get_project_detail() -> None:
     client, _, _, _ = _make_client()

apps/api/tests/test_templates.py

@@ -33,8 +33,13 @@ class _FakeTemplateRepo:
         self.rows[view.id] = view
         return view
 
-    async def list_for_owner(self, owner_id: uuid.UUID) -> list[TemplateView]:
-        return list(self.rows.values())
+    async def list_for_owner(
+        self, owner_id: uuid.UUID, *, limit: int | None = None, offset: int = 0
+    ) -> list[TemplateView]:
+        views = list(self.rows.values())
+        if limit is None:
+            return views
+        return views[offset : offset + limit]
 
     async def delete(self, owner_id: uuid.UUID, template_id: uuid.UUID) -> bool:
         if template_id in self.rows:

apps/api/ww_api/pagination.py

@@ -0,0 +1,37 @@
+"""列表端点的分页参数（`limit`/`offset`，边界校验 + 合理默认）。
+
+无界列表端点（owner 维度：projects / templates）原来一次返回全部行，行数随用户
+数据线性增长。这里提供一个可复用的 FastAPI 依赖 `get_page`，把 `limit`/`offset`
+在边界处校验（越界 → 422）后交端点。默认返回第一页（`offset=0` + `DEFAULT_PAGE_LIMIT`），
+不传参的老客户端行为不破坏；`limit` 有上限（`MAX_PAGE_LIMIT`）防一次性拉爆。
+"""
+
+from __future__ import annotations
+
+from dataclasses import dataclass
+from typing import Annotated
+
+from fastapi import Depends, Query
+
+# 合理默认 + 上限（单用户原型：默认页足够覆盖常见数据量；上限防一次拉全表）。
+DEFAULT_PAGE_LIMIT = 50
+MAX_PAGE_LIMIT = 200
+
+
+@dataclass(frozen=True)
+class Page:
+    """一页的边界（不可变）：`limit` 条数上限、`offset` 起始偏移。"""
+
+    limit: int
+    offset: int
+
+
+def get_page(
+    limit: Annotated[int, Query(ge=1, le=MAX_PAGE_LIMIT)] = DEFAULT_PAGE_LIMIT,
+    offset: Annotated[int, Query(ge=0)] = 0,
+) -> Page:
+    """校验并封装分页参数（`limit∈[1,MAX]`、`offset≥0`；越界 FastAPI 返 422）。"""
+    return Page(limit=limit, offset=offset)
+
+
+PageDep = Annotated[Page, Depends(get_page)]

apps/api/ww_api/routers/projects.py

@@ -46,6 +46,7 @@ from ww_llm_gateway import Gateway
 from ww_shared import AppError, ErrorCode, ErrorEnvelope
 
 from ww_api.logging_config import get_logger
+from ww_api.pagination import PageDep
 from ww_api.schemas.injection import (
     InjectionEntity,
     InjectionEntityRef,
@@ -144,8 +145,9 @@ async def create_project(body: ProjectCreateRequest, repo: ProjectRepoDep) -> Pr
 
 
 @router.get("")
-async def list_projects(repo: ProjectRepoDep) -> ProjectListResponse:
-    views = await repo.list_for_owner(STUB_OWNER_ID)
+async def list_projects(repo: ProjectRepoDep, page: PageDep) -> ProjectListResponse:
+    """作品列表（按 created_at 升序，分页）。`?limit=&offset=`，默认第一页。"""
+    views = await repo.list_for_owner(STUB_OWNER_ID, limit=page.limit, offset=page.offset)
     return ProjectListResponse(projects=[_to_response(v) for v in views])
 
 

apps/api/ww_api/routers/templates.py

@@ -23,6 +23,7 @@ from ww_db import get_session
 from ww_shared import AppError, ErrorCode
 
 from ww_api.logging_config import get_logger
+from ww_api.pagination import PageDep
 from ww_api.schemas.templates import TemplateCreateRequest, TemplateResponse
 from ww_api.services.credentials import STUB_OWNER_ID
 from ww_api.services.project_deps import get_template_repo
@@ -36,9 +37,9 @@ SessionDep = Annotated[AsyncSession, Depends(get_session)]
 
 
 @router.get("")
-async def list_templates(repo: TemplateRepoDep) -> list[TemplateResponse]:
-    """列出当前用户（stub）的模板。"""
-    views = await repo.list_for_owner(STUB_OWNER_ID)
+async def list_templates(repo: TemplateRepoDep, page: PageDep) -> list[TemplateResponse]:
+    """列出当前用户（stub）的模板（分页；`?limit=&offset=`，默认第一页）。"""
+    views = await repo.list_for_owner(STUB_OWNER_ID, limit=page.limit, offset=page.offset)
     return [
         TemplateResponse(
             id=v.id, title=v.title, body=v.body, category=v.category, tool_key=v.tool_key