feat(title): 标题自由位置拖拽后端支持——pos_x/pos_y 注入 \\pos 定位

工单 #1405 方案 B：前端支持用户在预览画面自由拖拽标题位置，
后端烧录 ASS 时按坐标定位。只动 Title，Subtitle 逻辑不变。

- title_config 新增可选字段 pos_x、pos_y（PlayRes 像素整数，
  PlayResX/Y = video_width/video_height）
- 两字段同时存在、为 int（bool/float/字符串拒绝）、且落在
  [0,video_width]×[0,video_height] 闭区间内时：
  - TitleStyle Alignment 固定 5（\an5 中对齐，\pos 锚点为文本块中心）
  - Dialogue 文本前注入 {\pos(x,y)} override tag
- 字段缺失/非法/越界一律回退 position → alignment 三档逻辑，
  现有 top/center/bottom 输出一字节不变
- 新增 9 个单测：合法坐标注入、边界值、无坐标回归、越界回退、
  非法类型回退（含 bool/float/None/字符串）、单字段回退、
  三档对齐不变、pos 覆盖 position、subtitle 不受影响

.gitea/workflows/ci-pipeline.yml

@@ -150,6 +150,7 @@ jobs:
       run: bash scripts/ci/step_timer_start.sh
     - name: Cache pip dependencies
       uses: actions/cache@v4
+      continue-on-error: true
       with:
         path: /root/.cache/pip
         key: ${{ runner.os }}-pip-style-${{ hashFiles('requirements*.txt') }}
@@ -252,6 +253,7 @@ jobs:
       run: bash scripts/ci/step_timer_start.sh
     - name: Cache pip dependencies
       uses: actions/cache@v4
+      continue-on-error: true
       with:
         path: /root/.cache/pip
         key: ${{ runner.os }}-pip-security-${{ hashFiles('requirements*.txt') }}
@@ -352,6 +354,7 @@ jobs:
       run: bash scripts/ci/step_timer_start.sh
     - name: Cache pip dependencies
       uses: actions/cache@v4
+      continue-on-error: true
       with:
         path: /root/.cache/pip
         key: ${{ runner.os }}-pip-python-${{ hashFiles('requirements*.txt') }}
@@ -456,6 +459,7 @@ jobs:
       run: bash scripts/ci/step_install_ffmpeg.sh
     - name: Cache pip dependencies
       uses: actions/cache@v4
+      continue-on-error: true
       with:
         path: /root/.cache/pip
         key: ${{ runner.os }}-pip-unittests-${{ hashFiles('requirements*.txt') }}
@@ -664,6 +668,7 @@ jobs:
       run: bash scripts/ci/step_timer_start.sh
     - name: Cache npm dependencies
       uses: actions/cache@v4
+      continue-on-error: true
       with:
         path: /root/.npm
         key: ${{ runner.os }}-npm-vitest-${{ hashFiles('apps/web/package-lock.json') }}

apps/api/app/api/routes/assets.py

@@ -579,39 +579,45 @@ def smart_match_assets(
         filtered_assets = asset_repository.find_by_library(request.library_id, status=["ready"], limit=10000)
     total_candidates = len(filtered_assets)
 
-    # 调用统一智能选素材算法（kind 已在 DB 层过滤，无需重复过滤）
-    results = smart_select_assets(
-        filtered_assets,
-        limit=request.limit,
-        kind=None,
-    )
+    # ── 过滤前置：余量 + 高频使用，过滤在评分/截取 limit 之前完成 ──────────
+    # 旧实现先 smart_select_assets(limit=N) 再对这 N 条做过滤，过滤后不回补，
+    # 当排名靠前的素材恰好都被排除时返回空 items（前端回退全选，smart-match 名存实亡）。
+    # 现在先过滤全量候选，每级过滤后为空/不足则回退上一级，最后才评分截取。
 
-    # 结果层过滤：usable=false（零重复可切区间耗尽且历史区间均达复用上限）的素材
-    # 不返回给前端；不动 smart_select_assets 评分逻辑本身
-    filtered_results = []
-    for r in results:
+    # 1) 余量过滤：usable=False（零重复可切区间耗尽且历史区间均达复用上限）的素材排除
+    usable_assets = []
+    exhausted_assets = []
+    for a in filtered_assets:
         try:
-            avail = compute_asset_availability(r.asset)
+            avail = compute_asset_availability(a)
         except Exception:
             logger.warning(
                 "smart-match 余量计算失败，按可用处理: asset_id=%s",
-                getattr(r.asset, "id", "?"),
+                getattr(a, "id", "?"),
                 exc_info=True,
             )
             avail = None
         if avail is not None and not avail["usable"]:
-            logger.info(
-                "smart-match 排除已用尽素材: asset_id=%s name=%s",
-                getattr(r.asset, "id", "?"),
-                getattr(r.asset, "name", ""),
-            )
-            continue
-        filtered_results.append(r)
+            exhausted_assets.append(a)
+        else:
+            usable_assets.append(a)
 
-    # 高频使用排除：同一素材在最近 5 个视频中出现超过 3 次则排除
+    if exhausted_assets:
+        logger.info(
+            "smart-match 余量过滤: 候选 %d，可切区间耗尽 %d",
+            len(filtered_assets), len(exhausted_assets),
+        )
+
+    # 回退策略：余量过滤后为空（全部耗尽）时，保留全部候选，不返回空结果。
+    # 宁可让用户在已耗尽素材上复用，也比 smart-match 空结果回退全选更可控
+    # （全选同样会选到这些素材，且不经过评分排序）。
+    pool = usable_assets if usable_assets else filtered_assets
+
+    # 2) 高频使用排除：同一素材在最近 5 个视频中出现超过 3 次则排除
     MAX_RECENT_USE_COUNT = 3
-    if filtered_results:
-        asset_ids = [getattr(r.asset, "id", "") for r in filtered_results if getattr(r.asset, "id", "")]
+    high_freq_assets = set()
+    if pool:
+        asset_ids = [getattr(a, "id", "") for a in pool if getattr(a, "id", "")]
         if asset_ids:
             try:
                 use_counts = get_asset_recent_use_counts(
@@ -619,27 +625,35 @@ def smart_match_assets(
                     asset_ids=asset_ids,
                     recent_video_count=5,
                 )
-                high_use_excluded = set()
-                for r in filtered_results:
-                    aid = getattr(r.asset, "id", "")
+                for a in pool:
+                    aid = getattr(a, "id", "")
                     count = use_counts.get(aid, 0)
                     if count > MAX_RECENT_USE_COUNT:
+                        high_freq_assets.add(aid)
                         logger.info(
                             "smart-match 排除高频使用素材: asset_id=%s use_count=%d limit=%d",
                             aid, count, MAX_RECENT_USE_COUNT,
                         )
-                        high_use_excluded.add(id(r))
+                # 回退策略：排除后剩余素材不足（为空或不够 limit）时，
+                # 不再全部排除，保留全部可用素材
+                if high_freq_assets:
+                    remaining_count = len(pool) - len(high_freq_assets)
+                    enough = request.limit is None or remaining_count >= request.limit
+                    if remaining_count > 0 and enough:
+                        pool = [a for a in pool if getattr(a, "id", "") not in high_freq_assets]
                     else:
-                        pass
-                # 如果排除后不够 limit，放宽到不限制
-                remaining = [r for r in filtered_results if id(r) not in high_use_excluded]
-                if len(remaining) >= request.limit:
-                    filtered_results = remaining
-                else:
-                    logger.info("smart-match 高频排除后素材不足(%d<%d)，保留全部", len(remaining), request.limit)
+                        logger.info(
+                            "smart-match 高频排除后素材不足(%d<%s)，保留全部 %d 条",
+                            remaining_count,
+                            request.limit if request.limit is not None else "不限",
+                            len(pool),
+                        )
             except Exception:
                 logger.warning("smart-match 高频使用查询失败，跳过排除", exc_info=True)
 
+    # 3) 调用统一智能选素材算法（kind 已在 DB 层过滤，无需重复过滤）
+    results = smart_select_assets(pool, limit=request.limit, kind=None)
+
     # 扁平结构：SmartMatchItem 继承 AssetResponse，素材字段直接在条目顶层，
     # 前端无需解析 item.asset 包装层，item.id / item.usable / 余量字段直接可读
     items = [
@@ -648,7 +662,7 @@ def smart_match_assets(
             score=r.score,
             breakdown=r.breakdown,
         )
-        for r in filtered_results
+        for r in results
     ]
 
     return SmartMatchResponse(items=items, total_candidates=total_candidates)

apps/web/src/pages/generate/components/material/MaterialModeTabs.tsx

@@ -23,7 +23,7 @@ const MaterialModeTabs: React.FC<MaterialModeTabsProps> = ({ mode, onModeChange
         onClick={() => onModeChange("auto")}
         type="button"
       >
-        选择视频库自动匹配
+        AI智能匹配
       </button>
     </div>
   )

apps/web/src/pages/products/components/ProductCard.tsx

@@ -11,7 +11,7 @@ import {
 } from "@ant-design/icons"
 import type { ProductItem } from "../types"
 import { statusConfig, reviewStatusConfig } from "../constants"
-import { formatTime } from "../utils"
+import { formatTime, formatSize } from "../utils"
 
 interface ProductCardProps {
   product: ProductItem
@@ -210,11 +210,20 @@ export const ProductCard: React.FC<ProductCardProps> = ({
           <span className={`xx-product-status ${st.className}`}>{st.text}</span>
           <span className="xx-product-date">{product.date}</span>
         </div>
-        {product.duplicateRate > 0 && (
-          <span className={`xx-product-dup-rate ${dupClass}`}>
-            查重率：{product.duplicateRate.toFixed(1)}%
+        <div className="xx-product-meta-grid">
+          <span className="xx-product-meta-item">分辨率：{product.resolution || "-"}</span>
+          <span className="xx-product-meta-item">
+            时长：{product.duration > 0 ? formatTime(product.duration) : "-"}
           </span>
-        )}
+          <span className="xx-product-meta-item">大小：{formatSize(product.fileSize)}</span>
+          <span
+            className={`xx-product-meta-item xx-product-dup-rate${
+              product.duplicateRate > 0 ? ` ${dupClass}` : ""
+            }`}
+          >
+            查重率：{product.duplicateRate > 0 ? `${product.duplicateRate.toFixed(1)}%` : "-"}
+          </span>
+        </div>
       </div>
 
       {/* 操作按钮 */}

apps/web/src/pages/products/products.css

@@ -276,11 +276,11 @@
   background-position: center;
 }
 
-/* 内联视频播放器 */
+/* 内联视频播放器（cover 填满容器，竖屏视频不留左右空白） */
 .xx-product-thumb-video {
   width: 100%;
   height: 100%;
-  object-fit: contain;
+  object-fit: cover;
   display: block;
 }
 
@@ -347,6 +347,21 @@
   gap: var(--space-xs);
 }
 
+/* 卡片信息网格：分辨率/时长 一行，大小/查重率 一行 */
+.xx-product-meta-grid {
+  display: grid;
+  grid-template-columns: 1fr 1fr;
+  gap: 4px var(--space-sm);
+}
+
+.xx-product-meta-item {
+  font-size: var(--font-size-xs);
+  color: var(--text-secondary);
+  white-space: nowrap;
+  overflow: hidden;
+  text-overflow: ellipsis;
+}
+
 /* 状态标签 */
 .xx-product-status {
   padding: 2px 10px;

infra/docker/ci.Dockerfile

@@ -30,6 +30,14 @@ RUN apt-get update \
     && apt-get install -y --no-install-recommends docker-ce-cli docker-buildx-plugin \
     && rm -rf /var/lib/apt/lists/*
 
+# Pre-bake ffmpeg: unit-tests run in fresh containers each time; installing ffmpeg
+# on every job cost ~24 min (apt update + hundreds of codec deps). Bake it into the
+# image so step_install_ffmpeg.sh detects it and exits instantly.
+RUN apt-get update \
+    && apt-get install -y --no-install-recommends ffmpeg \
+    && ffmpeg -version | head -1 \
+    && rm -rf /var/lib/apt/lists/*
+
 # Pre-install base deps (layer cache)
 COPY requirements-base.txt ./
 RUN python -m venv "$VIRTUAL_ENV" \

packages/domain/ass_subtitle_builder.py

@@ -256,6 +256,42 @@ def _wrap_title_text(
     return "\\N".join(wrapped_segments)
 
 
+def _parse_title_position(
+    title_config: dict[str, Any],
+    video_width: int,
+    video_height: int,
+) -> tuple[int, int] | None:
+    """解析标题自由拖拽坐标 pos_x/pos_y（PlayRes 像素坐标系）。
+
+    要求两个字段同时存在、可转 int，且落在 [0, video_width] × [0, video_height]
+    闭区间内。任一条件不满足返回 None，调用方回退 position 三档逻辑。
+
+    Args:
+        title_config: 标题配置 dict
+        video_width: PlayResX（视频宽度像素）
+        video_height: PlayResY（视频高度像素）
+
+    Returns:
+        (x, y) 整数坐标，或 None 表示不使用自由位置
+    """
+    if "pos_x" not in title_config or "pos_y" not in title_config:
+        return None
+    raw_x = title_config["pos_x"]
+    raw_y = title_config["pos_y"]
+    # 坐标必须是 PlayRes 像素整数：bool 是 int 子类（isinstance(True,int)=True）
+    # 但 True/False 作坐标无意义；float 静默截断会造成拖拽位置偏差，一律按非法回退
+    if isinstance(raw_x, bool) or isinstance(raw_y, bool):
+        return None
+    if not isinstance(raw_x, int) or not isinstance(raw_y, int):
+        return None
+    x, y = raw_x, raw_y
+    if video_width <= 0 or video_height <= 0:
+        return None
+    if not (0 <= x <= video_width and 0 <= y <= video_height):
+        return None
+    return (x, y)
+
+
 def build_ass_content(
     *,
     video_width: int,
@@ -343,7 +379,16 @@ def build_ass_content(
             title_shadow.get("offset_y", 2) if title_shadow.get("enabled", False) else 0,
         )
 
-        title_alignment = position_to_ass_alignment(title_config.get("position", "top"))
+        # ── 自由位置拖拽（工单 #1405 方案 B）────────────────────────────
+        # pos_x/pos_y 为 PlayRes 坐标系像素整数（PlayResX/Y = video_width/height）。
+        # 合法时：TitleStyle Alignment 固定 5（\an5 中对齐，使 \pos 锚点为文本块中心），
+        # Dialogue 文本前注入 {\pos(x,y)}。字段缺失/非法/越界时一律回退
+        # position → alignment 三档逻辑，现有输出保持一字节不变。
+        title_pos = _parse_title_position(title_config, video_width, video_height)
+
+        title_alignment = 5 if title_pos is not None else position_to_ass_alignment(
+            title_config.get("position", "top")
+        )
 
         styles.append(
             build_ass_style(
@@ -370,6 +415,10 @@ def build_ass_content(
         safe_title_text_raw = escape_ass_text(title_text)
         safe_title_text = _wrap_title_text(safe_title_text_raw, video_width, title_font_size)
 
+        # 自由位置：在文本前注入 \pos override tag（锚点为文本块中心，配合 \an5）
+        if title_pos is not None:
+            safe_title_text = f"{{\\pos({title_pos[0]},{title_pos[1]})}}{safe_title_text}"
+
         events.append(
             "Dialogue: 0,0:00:00.00," f"{format_ass_time(video_duration)}," "TitleStyle,,0,0,0,," f"{safe_title_text}"
         )

tests/unit/test_ass_subtitle_builder.py

@@ -602,3 +602,148 @@ class TestFontsizeCompensation:
         result = build_ass_style("S", font_size=0)
         parts = result.split(",")
         assert int(parts[2]) >= 1
+
+
+# ── 标题自由位置拖拽（工单 #1405 方案 B）──────────────────────────────────────
+
+
+def _title_style_line(content: str) -> str:
+    return [line for line in content.splitlines() if line.startswith("Style: TitleStyle")][0]
+
+
+def _title_dialogue_line(content: str) -> str:
+    return [line for line in content.splitlines() if line.startswith("Dialogue:") and "TitleStyle" in line][0]
+
+
+class TestTitleFreePosition:
+    """pos_x/pos_y 合法时注入 \\pos 且 Alignment=5；非法/缺失时回退原逻辑。"""
+
+    def _base_kwargs(self):
+        return dict(
+            video_width=1080,
+            video_height=1920,
+            video_duration=8.0,
+            title_text="测试标题",
+        )
+
+    def test_valid_position_injects_pos_tag_and_alignment_5(self):
+        content = build_ass_content(
+            **self._base_kwargs(),
+            title_config={"position": "top", "size": 36, "pos_x": 540, "pos_y": 300},
+        )
+        # Dialogue 文本前注入 {\pos(540,300)}
+        dialogue = _title_dialogue_line(content)
+        assert "{\\pos(540,300)}" in dialogue
+        # TitleStyle Alignment 固定 5（\an5 中对齐，\pos 锚点为文本块中心）
+        fields = [f.strip() for f in _title_style_line(content).split(",")]
+        assert fields[18] == "5"
+
+    def test_boundary_coordinates_zero_and_max_accepted(self):
+        """边界值 0 和 video_width/video_height 合法（闭区间）。"""
+        content = build_ass_content(
+            **self._base_kwargs(),
+            title_config={"pos_x": 0, "pos_y": 1920},
+        )
+        assert "{\\pos(0,1920)}" in _title_dialogue_line(content)
+
+        content2 = build_ass_content(
+            **self._base_kwargs(),
+            title_config={"pos_x": 1080, "pos_y": 0},
+        )
+        assert "{\\pos(1080,0)}" in _title_dialogue_line(content2)
+
+    def test_no_coords_output_identical_to_before(self):
+        """不传坐标 → 输出与现有断言完全一致（回归保护）。"""
+        content = build_ass_content(
+            **self._base_kwargs(),
+            title_config={"position": "top", "size": 36},
+        )
+        # 无 \pos 注入
+        assert "\\pos(" not in content
+        # Alignment 走 position 映射（top → 8）
+        fields = [f.strip() for f in _title_style_line(content).split(",")]
+        assert fields[18] == "8"
+
+    def test_out_of_bounds_falls_back(self):
+        """越界坐标 → 回退 position 三档逻辑，输出与无坐标一致。"""
+        base = build_ass_content(
+            **self._base_kwargs(),
+            title_config={"position": "top", "size": 36},
+        )
+        for pos_x, pos_y in [(-1, 300), (540, -1), (1081, 300), (540, 1921), (99999, 99999)]:
+            content = build_ass_content(
+                **self._base_kwargs(),
+                title_config={"position": "top", "size": 36, "pos_x": pos_x, "pos_y": pos_y},
+            )
+            assert "\\pos(" not in content, f"({pos_x},{pos_y}) should be rejected"
+            assert content == base, f"({pos_x},{pos_y}) output differs from fallback"
+
+    def test_invalid_coords_falls_back(self):
+        """非法类型坐标 → 回退原逻辑。"""
+        base = build_ass_content(
+            **self._base_kwargs(),
+            title_config={"position": "top", "size": 36},
+        )
+        for pos_x, pos_y in [("abc", 300), (540, None), (None, None), (True, 300), (540, False), (540.5, 300.9)]:
+            content = build_ass_content(
+                **self._base_kwargs(),
+                title_config={"position": "top", "size": 36, "pos_x": pos_x, "pos_y": pos_y},
+            )
+            assert "\\pos(" not in content, f"({pos_x!r},{pos_y!r}) should be rejected"
+            assert content == base, f"({pos_x!r},{pos_y!r}) output differs from fallback"
+
+    def test_only_one_coord_falls_back(self):
+        """只传 pos_x 或 pos_y → 回退原逻辑。"""
+        base = build_ass_content(
+            **self._base_kwargs(),
+            title_config={"position": "center", "size": 36},
+        )
+        content_x = build_ass_content(
+            **self._base_kwargs(),
+            title_config={"position": "center", "size": 36, "pos_x": 540},
+        )
+        content_y = build_ass_content(
+            **self._base_kwargs(),
+            title_config={"position": "center", "size": 36, "pos_y": 300},
+        )
+        assert content_x == base
+        assert content_y == base
+        assert "\\pos(" not in content_x
+        assert "\\pos(" not in content_y
+
+    def test_position_three_levels_unchanged_without_coords(self):
+        """无坐标时 top/center/bottom 三档 Alignment 输出不变。"""
+        for position, expected_align in [("top", "8"), ("center", "5"), ("bottom", "2")]:
+            content = build_ass_content(
+                **self._base_kwargs(),
+                title_config={"position": position, "size": 36},
+            )
+            fields = [f.strip() for f in _title_style_line(content).split(",")]
+            assert fields[18] == expected_align
+
+    def test_pos_overrides_position_alignment(self):
+        """有合法坐标时，无论 position 是什么，Alignment 都固定为 5。"""
+        for position in ["top", "center", "bottom"]:
+            content = build_ass_content(
+                **self._base_kwargs(),
+                title_config={"position": position, "size": 36, "pos_x": 100, "pos_y": 200},
+            )
+            fields = [f.strip() for f in _title_style_line(content).split(",")]
+            assert fields[18] == "5"
+            assert "{\\pos(100,200)}" in _title_dialogue_line(content)
+
+    def test_subtitle_not_affected_by_pos(self):
+        """pos_x/pos_y 只影响 Title，Subtitle 输出不变。"""
+        content = build_ass_content(
+            **self._base_kwargs(),
+            title_config={"pos_x": 540, "pos_y": 300},
+            subtitle_text="配音字幕",
+            subtitle_config={"position": "bottom", "size": 24},
+        )
+        sub_style = [line for line in content.splitlines() if line.startswith("Style: SubtitleStyle")][0]
+        sub_fields = [f.strip() for f in sub_style.split(",")]
+        assert sub_fields[18] == "2"  # bottom
+        sub_dialogue = [
+            line for line in content.splitlines() if line.startswith("Dialogue:") and "SubtitleStyle" in line
+        ][0]
+        assert "\\pos(" not in sub_dialogue

tests/unit/test_asset_availability.py

@@ -395,11 +395,13 @@ class TestSmartMatchFiltersExhausted:
         # 返回的素材全部 usable=True
         assert all(item.usable for item in resp.items)
 
-    def test_all_exhausted_returns_empty(self):
-        """全部素材已用尽时返回空列表（不报错，前端显示空结果）。"""
+    def test_all_exhausted_falls_back_to_all(self):
+        """全部素材已用尽时回退保留全部（不返回空——空结果会让前端回退全选，
+        反而绕过评分排序；耗尽素材仍可走复用区间）。"""
         assets = [_exhausted_asset("a-ex-1"), _exhausted_asset("a-ex-2")]
         resp = self._call(assets)
-        assert resp.items == []
+        returned_ids = {item.id for item in resp.items}
+        assert returned_ids == {"a-ex-1", "a-ex-2"}
         assert resp.total_candidates == 2
 
     def test_fresh_assets_all_returned(self):

tests/unit/test_smart_match_fallback.py

@@ -0,0 +1,258 @@
+"""smart-match 过滤回退策略测试：余量过滤/高频排除导致结果集为空时必须回退。
+
+线上事故：路由旧实现先 smart_select_assets(limit=N) 截取，再对这 N 条做
+usable / 高频过滤，过滤后不回补——排名靠前素材全部被排除时返回空 items，
+前端回退全选。修复后过滤全部前置，且每级过滤后为空/不足时回退保留。
+"""
+
+import json
+import os
+import sys
+from pathlib import Path
+from unittest.mock import MagicMock
+
+os.environ.setdefault("JWT_SECRET_KEY", "unit-test-secret-key-for-testing")
+os.environ.setdefault("DATABASE_URL", "sqlite:///test.db")
+
+import pytest
+from fastapi import FastAPI
+from fastapi.testclient import TestClient
+
+ROOT = Path(__file__).resolve().parents[2]
+sys.path.insert(0, str(ROOT / "apps" / "api"))
+sys.path.insert(0, str(ROOT / "packages"))
+
+from app.api.routes.assets import router
+from app.auth import AuthenticatedUser, get_current_user
+from app.core.storage import get_storage_service
+from app.dependencies import (
+    get_asset_library_repository,
+    get_asset_repository,
+    get_project_repository,
+)
+
+from packages.domain import (
+    Asset,
+    AssetLibrary,
+    AssetLibraryKind,
+    AssetStatus,
+    Project,
+    User,
+)
+
+
+class _StubProjectRepo:
+    def __init__(self, projects):
+        self._projects = projects
+
+    def find_by_id(self, pid):
+        return self._projects.get(pid)
+
+
+class _StubAssetLibraryRepo:
+    def __init__(self, libraries):
+        self._libraries = libraries
+
+    def get(self, lid):
+        return self._libraries.get(lid)
+
+
+class _StubAssetRepo:
+    """模拟仓储；session 属性供 get_asset_recent_use_counts 使用（测试中会被 patch）。"""
+
+    def __init__(self, assets):
+        self._assets = assets
+        self.session = MagicMock(name="stub-session")
+
+    def find_by_library(self, lid, skip=0, limit=100, status=None):
+        result = [a for a in self._assets if a.library_id == lid]
+        if status:
+            result = [a for a in result if (a.status.value if hasattr(a.status, "value") else a.status) in status]
+        return result[skip : skip + limit]
+
+    def find_by_library_and_file_type(self, lid, file_type, skip=0, limit=100, status=None):
+        result = [a for a in self._assets if a.library_id == lid and a.file_type == file_type]
+        if status:
+            result = [a for a in result if (a.status.value if hasattr(a.status, "value") else a.status) in status]
+        return result[skip : skip + limit]
+
+
+def _make_app(asset_repo, lib_repo, proj_repo):
+    app = FastAPI()
+    app.include_router(router, prefix="/assets")
+    fake_user = MagicMock()
+    fake_user.user = User(id="user-1", email="test@test.com", display_name="Test")
+    app.dependency_overrides[get_current_user] = lambda: AuthenticatedUser(user=fake_user.user)
+    app.dependency_overrides[get_asset_repository] = lambda: asset_repo
+    app.dependency_overrides[get_asset_library_repository] = lambda: lib_repo
+    app.dependency_overrides[get_project_repository] = lambda: proj_repo
+    app.dependency_overrides[get_storage_service] = lambda: MagicMock()
+    return app
+
+
+def _library():
+    return AssetLibrary(id="lib-1", project_id="proj-1", name="Videos", kind=AssetLibraryKind.VIDEO)
+
+
+def _exhausted_ranges(duration=15.0):
+    """构造 used_time_ranges：整片覆盖 + 每区间 use_count 达上限 3 → usable=False。"""
+    return [
+        {"start": 0.0, "end": duration, "use_count": 3, "plan_id": "p1"},
+    ]
+
+
+def _video_asset(name, duration=15.0, quality=90, used_ranges=None):
+    meta = {"used_time_ranges": used_ranges} if used_ranges is not None else {}
+    return Asset.create(
+        project_id="proj-1",
+        library_id="lib-1",
+        name=name,
+        storage_key=f"key-{name}",
+        mime_type="video/mp4",
+        metadata=meta,
+        quality_score=quality,
+        duration=duration,
+        status=AssetStatus.READY,
+    )
+
+
+class TestSmartMatchAvailabilityFallback:
+    """余量过滤回退：全部素材 usable=False 时不返回空。"""
+
+    def test_all_exhausted_returns_assets_instead_of_empty(self):
+        project = Project(id="proj-1", name="Test", owner_user_id="user-1")
+        assets = [
+            _video_asset("v1.mp4", used_ranges=_exhausted_ranges(15)),
+            _video_asset("v2.mp4", used_ranges=_exhausted_ranges(25)),
+        ]
+        repo = _StubAssetRepo(assets)
+        app = _make_app(repo, _StubAssetLibraryRepo({"lib-1": _library()}), _StubProjectRepo({"proj-1": project}))
+        with TestClient(app) as client:
+            resp = client.post("/assets/smart-match", json={"library_id": "lib-1"})
+        assert resp.status_code == 200, resp.text
+        data = resp.json()
+        # 回退：保留全部候选，不返回空
+        assert len(data["items"]) == 2
+        assert data["total_candidates"] == 2
+
+    def test_mixed_exhausted_and_fresh_excludes_exhausted(self):
+        project = Project(id="proj-1", name="Test", owner_user_id="user-1")
+        assets = [
+            _video_asset("exhausted.mp4", quality=99, used_ranges=_exhausted_ranges(15)),
+            _video_asset("fresh.mp4", quality=50, used_ranges=None),
+        ]
+        repo = _StubAssetRepo(assets)
+        app = _make_app(repo, _StubAssetLibraryRepo({"lib-1": _library()}), _StubProjectRepo({"proj-1": project}))
+        with TestClient(app) as client:
+            resp = client.post("/assets/smart-match", json={"library_id": "lib-1"})
+        assert resp.status_code == 200, resp.text
+        names = [item["name"] for item in resp.json()["items"]]
+        assert "fresh.mp4" in names
+        assert "exhausted.mp4" not in names
+
+    def test_limit_backfills_from_lower_ranked_when_top_exhausted(self):
+        """limit=1 且排名第一的素材耗尽时，必须回补排名靠后的可用素材，不返回空。"""
+        project = Project(id="proj-1", name="Test", owner_user_id="user-1")
+        assets = [
+            _video_asset("top-exhausted.mp4", quality=100, used_ranges=_exhausted_ranges(15)),
+            _video_asset("second-fresh.mp4", quality=40, used_ranges=None),
+            _video_asset("third-fresh.mp4", quality=30, used_ranges=None),
+        ]
+        repo = _StubAssetRepo(assets)
+        app = _make_app(repo, _StubAssetLibraryRepo({"lib-1": _library()}), _StubProjectRepo({"proj-1": project}))
+        with TestClient(app) as client:
+            resp = client.post("/assets/smart-match", json={"library_id": "lib-1", "limit": 1})
+        assert resp.status_code == 200, resp.text
+        data = resp.json()
+        assert len(data["items"]) == 1
+        # 不能是空，也不能是耗尽的高分素材
+        assert data["items"][0]["name"] == "second-fresh.mp4"
+
+
+class TestSmartMatchHighFreqFallback:
+    """高频排除回退：排除后为空/不足 limit 时保留全部可用素材。"""
+
+    def test_all_high_freq_keeps_all(self, monkeypatch):
+        import app.api.routes.assets as routes_mod
+
+        project = Project(id="proj-1", name="Test", owner_user_id="user-1")
+        assets = [_video_asset("v1.mp4", quality=90), _video_asset("v2.mp4", quality=80)]
+        repo = _StubAssetRepo(assets)
+
+        # 全部素材在最近 5 个视频中使用 5 次（> 3）
+        fake_counts = {assets[0].id: 5, assets[1].id: 5}
+        monkeypatch.setattr(
+            routes_mod, "get_asset_recent_use_counts", lambda db, asset_ids, recent_video_count=5: fake_counts
+        )
+
+        app = _make_app(repo, _StubAssetLibraryRepo({"lib-1": _library()}), _StubProjectRepo({"proj-1": project}))
+        with TestClient(app) as client:
+            resp = client.post("/assets/smart-match", json={"library_id": "lib-1"})
+        assert resp.status_code == 200, resp.text
+        data = resp.json()
+        # 全部高频 → 回退保留全部
+        assert len(data["items"]) == 2
+
+    def test_high_freq_partial_exclusion_with_enough_remaining(self, monkeypatch):
+        import app.api.routes.assets as routes_mod
+
+        project = Project(id="proj-1", name="Test", owner_user_id="user-1")
+        assets = [
+            _video_asset("hot.mp4", quality=99),
+            _video_asset("cool1.mp4", quality=80),
+            _video_asset("cool2.mp4", quality=70),
+        ]
+        repo = _StubAssetRepo(assets)
+        fake_counts = {assets[0].id: 9, assets[1].id: 1, assets[2].id: 0}
+        monkeypatch.setattr(
+            routes_mod, "get_asset_recent_use_counts", lambda db, asset_ids, recent_video_count=5: fake_counts
+        )
+
+        app = _make_app(repo, _StubAssetLibraryRepo({"lib-1": _library()}), _StubProjectRepo({"proj-1": project}))
+        with TestClient(app) as client:
+            resp = client.post("/assets/smart-match", json={"library_id": "lib-1"})
+        assert resp.status_code == 200, resp.text
+        names = [item["name"] for item in resp.json()["items"]]
+        assert "hot.mp4" not in names
+        assert set(names) == {"cool1.mp4", "cool2.mp4"}
+
+    def test_high_freq_insufficient_for_limit_keeps_all(self, monkeypatch):
+        """3 个素材、limit=5、2 个高频 → 剩余 1 < limit → 保留全部。"""
+        import app.api.routes.assets as routes_mod
+
+        project = Project(id="proj-1", name="Test", owner_user_id="user-1")
+        assets = [
+            _video_asset("hot1.mp4", quality=99),
+            _video_asset("hot2.mp4", quality=98),
+            _video_asset("cool.mp4", quality=50),
+        ]
+        repo = _StubAssetRepo(assets)
+        fake_counts = {assets[0].id: 8, assets[1].id: 7, assets[2].id: 0}
+        monkeypatch.setattr(
+            routes_mod, "get_asset_recent_use_counts", lambda db, asset_ids, recent_video_count=5: fake_counts
+        )
+
+        app = _make_app(repo, _StubAssetLibraryRepo({"lib-1": _library()}), _StubProjectRepo({"proj-1": project}))
+        with TestClient(app) as client:
+            resp = client.post("/assets/smart-match", json={"library_id": "lib-1", "limit": 5})
+        assert resp.status_code == 200, resp.text
+        names = [item["name"] for item in resp.json()["items"]]
+        # 剩余 1 < limit=5 → 回退保留全部 3 条
+        assert set(names) == {"hot1.mp4", "hot2.mp4", "cool.mp4"}
+
+    def test_high_freq_query_failure_skips_exclusion(self, monkeypatch):
+        import app.api.routes.assets as routes_mod
+
+        def _boom(db, asset_ids, recent_video_count=5):
+            raise RuntimeError("DB down")
+
+        project = Project(id="proj-1", name="Test", owner_user_id="user-1")
+        assets = [_video_asset("v1.mp4", quality=90), _video_asset("v2.mp4", quality=80)]
+        repo = _StubAssetRepo(assets)
+        monkeypatch.setattr(routes_mod, "get_asset_recent_use_counts", _boom)
+
+        app = _make_app(repo, _StubAssetLibraryRepo({"lib-1": _library()}), _StubProjectRepo({"proj-1": project}))
+        with TestClient(app) as client:
+            resp = client.post("/assets/smart-match", json={"library_id": "lib-1"})
+        assert resp.status_code == 200, resp.text
+        assert len(resp.json()["items"]) == 2