diff --git a/apps/worker/video_processing/trim_engine.py b/apps/worker/video_processing/trim_engine.py
index 62bf6f88a..6cae5a00b 100755
--- a/apps/worker/video_processing/trim_engine.py
+++ b/apps/worker/video_processing/trim_engine.py
@@ -5,6 +5,8 @@
 - 边界自动钳制（超出素材时长自动修正，不阻断渲染）
 - 多段裁剪（一个素材裁剪出多段）
 - 音画同步（视频 + 音频同步裁剪）
+
+领域模型已抽离到 packages/domain/trim_config.py，本模块保留薄包装。
 """
 
 from __future__ import annotations
@@ -13,157 +15,50 @@ import logging
 from dataclasses import dataclass
 from typing import Any
 
+from packages.domain.trim_config import (  # noqa: F401 — 向后兼容
+    MIN_TRIM_DURATION as _min_trim_duration_base,
+    TrimConfig,
+    TrimSegment,
+)
+
 logger = logging.getLogger(__name__)
 
-# 最小裁剪时长（秒），低于此值视为无效
-MIN_TRIM_DURATION = 0.1
+# 向后兼容：MIN_TRIM_DURATION 从 domain 层导出
+MIN_TRIM_DURATION = _min_trim_duration_base
 
 
-@dataclass
-class TrimConfig:
-    """裁剪配置.
+# 向后兼容：extract_trim_from_clip_config 保留在本模块
+def extract_trim_from_clip_config(config: dict[str, Any] | None) -> TrimConfig | None:
+    """从 clip.config 中提取裁剪配置.
 
-    三选二规则：start_time / end_time / duration 中必须至少给出两个，
-    第三个会被自动推导。如果三个都给了，以 start_time + duration 为准。
-
-    边界保护：
-    - start_time < 0 → 钳制到 0
-    - end_time > 素材时长 → 钳制到素材时长
-    - 计算出的 duration < 最小阈值 → 标记为无效
+    兼容多种字段命名：
+    - trim: { start_time, end_time, duration }
+    - 直接使用 start_time / end_time / duration 字段
     """
+    if not config:
+        return None
 
-    start_time: float = 0.0  # 入点（素材内时间，秒）
-    end_time: float = 0.0  # 出点（素材内时间，秒），0 表示未指定
-    duration: float = 0.0  # 裁剪时长（秒），0 表示未指定
+    # 优先使用 trim 子对象
+    trim_data = config.get("trim")
+    if trim_data and isinstance(trim_data, dict):
+        return TrimConfig.from_dict(trim_data)
 
-    @classmethod
-    def from_dict(cls, data: dict[str, Any] | None) -> TrimConfig | None:
-        """从字典构造，无有效裁剪参数时返回 None（不裁剪）."""
-        if not data:
-            return None
+    # 兼容：直接从 config 读取裁剪字段
+    has_trim_field = any(
+        config.get(k) not in (None, 0, 0.0, "")
+        for k in ("trim_start", "trim_end", "trim_duration", "start_time", "end_time", "duration")
+    )
+    if not has_trim_field:
+        return None
 
-        start = float(data.get("start_time", 0) or 0)
-        end = float(data.get("end_time", 0) or 0)
-        dur = float(data.get("duration", 0) or 0)
+    # 映射字段名（支持 trim_ 前缀和无前缀两种）
+    start = config.get("trim_start") or config.get("start_time") or 0
+    end = config.get("trim_end") or config.get("end_time") or 0
+    dur = config.get("trim_duration") or config.get("duration") or 0
 
-        # 三个参数都没有 → 不裁剪
-        if start <= 0 and end <= 0 and dur <= 0:
-            return None
-
-        # 至少有两个参数（或一个合理的 start/duration）
-        # 兼容：只传了 start_time → 从 start 开始取到末尾
-        # 兼容：只传了 duration → 从 0 开始取 duration
-        if start > 0 and end <= 0 and dur <= 0:
-            # 只有 start，取到末尾 → 这是"从某点开始"的语义，算有效
-            pass
-        elif dur > 0 and start <= 0 and end <= 0:
-            # 只有 duration → 从开头取 duration，算有效
-            pass
-        elif start <= 0 and end <= 0 and dur <= 0:
-            return None
-
-        return cls(start_time=start, end_time=end, duration=dur)
-
-    def validate_and_resolve(self, asset_duration: float) -> TrimConfig:
-        """根据素材实际时长，解析并钳制裁剪参数.
-
-        返回一个新的 TrimConfig，其中 start_time / end_time / duration 都已确定。
-        如果裁剪无效（时长为0或负数），仍返回但调用方应检查 is_valid。
-        """
-        start = self.start_time
-        end = self.end_time
-        dur = self.duration
-
-        # 边界：start 不能为负
-        if start < 0:
-            start = 0.0
-
-        # 边界：asset_duration 为 0 时保守处理（不裁剪，取全部）
-        if asset_duration <= 0:
-            return TrimConfig(start_time=0.0, end_time=0.0, duration=0.0)
-
-        # 三选二推导
-        # 判断顺序很重要：先判断需要两个显式值的组合，最后判断含默认值的
-        # 情况1：start + end 都有显式值
-        if start > 0 and end > 0:
-            if end <= start:
-                # 出点 <= 入点，无效 → 返回 start 处一个极短片段（调用方会判无效）
-                return TrimConfig(start_time=start, end_time=start, duration=0.0)
-            dur = end - start
-        # 情况2：end + duration 都有显式值
-        elif end > 0 and dur > 0:
-            start = end - dur
-            if start < 0:
-                start = 0.0
-                dur = end  # 重新计算
-        # 情况3：start + duration 都有值（start 可以是 0）
-        elif dur > 0:
-            end = start + dur
-        # 情况4：只有 start → 取到素材末尾
-        elif start > 0 and end <= 0 and dur <= 0:
-            end = asset_duration
-            dur = end - start
-        # 情况5：只有 end → 从开头取到 end
-        elif end > 0 and start <= 0 and dur <= 0:
-            start = 0.0
-            dur = end
-        else:
-            # 都没有 → 不裁剪
-            return TrimConfig(start_time=0.0, end_time=0.0, duration=0.0)
-
-        # 边界钳制：end 不能超过素材时长
-        if end > asset_duration:
-            end = asset_duration
-            dur = end - start
-
-        # 边界钳制：start 不能超过素材时长
-        if start >= asset_duration:
-            start = max(0.0, asset_duration - MIN_TRIM_DURATION)
-            dur = asset_duration - start
-            end = asset_duration
-
-        # 保证 duration 不为负
-        if dur < 0:
-            dur = 0.0
-
-        return TrimConfig(start_time=start, end_time=end, duration=dur)
-
-    @property
-    def is_valid(self) -> bool:
-        """裁剪是否有效（时长大于最小阈值）."""
-        return self.duration >= MIN_TRIM_DURATION
-
-    @property
-    def is_noop(self) -> bool:
-        """是否等价于不裁剪（从0开始取全部）."""
-        return self.start_time <= 0 and self.duration <= 0
-
-    @property
-    def trim_from_start(self) -> bool:
-        """是否从开头裁剪（start_time == 0）."""
-        return self.start_time <= 0
-
-
-@dataclass
-class TrimSegment:
-    """多段裁剪中的一段."""
-
-    segment_id: str  # 段 ID（用于生成唯一标签）
-    trim: TrimConfig  # 裁剪配置
-    order: int = 0  # 排序
-
-    @classmethod
-    def from_dict(cls, data: dict[str, Any], default_order: int = 0) -> TrimSegment:
-        """从字典构造."""
-        return cls(
-            segment_id=str(data.get("segment_id", "") or f"seg_{default_order}"),
-            trim=TrimConfig(
-                start_time=float(data.get("start_time", 0) or 0),
-                end_time=float(data.get("end_time", 0) or 0),
-                duration=float(data.get("duration", 0) or 0),
-            ),
-            order=int(data.get("order", default_order)),
-        )
+    return TrimConfig.from_dict(
+        {"start_time": start, "end_time": end, "duration": dur}
+    )
 
 
 class TrimEngine:
@@ -308,32 +203,3 @@ class TrimEngine:
 
         return []
 
-
-# ── 工具函数 ──────────────────────────────────────────────────────────────────
-
-
-def extract_trim_from_clip_config(config: dict[str, Any] | None) -> TrimConfig | None:
-    """从 clip config 中提取单段裁剪配置.
-
-    兼容以下字段名：
-    - trim_start / trim_end / trim_duration
-    - start_time / end_time / duration（在 trim 子字典里）
-    """
-    if not config:
-        return None
-
-    # trim 子字典
-    if "trim" in config and isinstance(config["trim"], dict):
-        return TrimConfig.from_dict(config["trim"])
-
-    # 扁平字段
-    has_any = any(k in config for k in ("trim_start", "trim_end", "trim_duration"))
-    if not has_any:
-        return None
-
-    data = {
-        "start_time": config.get("trim_start", 0),
-        "end_time": config.get("trim_end", 0),
-        "duration": config.get("trim_duration", 0),
-    }
-    return TrimConfig.from_dict(data)
diff --git a/packages/domain/trim_config.py b/packages/domain/trim_config.py
new file mode 100755
index 000000000..9b5ad8d97
--- /dev/null
+++ b/packages/domain/trim_config.py
@@ -0,0 +1,166 @@
+"""裁剪配置领域模型 — 纯逻辑，无FFmpeg依赖.
+
+抽离自 trim_engine.py，包含：
+- TrimConfig 数据类（三选二推导 + 边界钳制 + 有效性判断）
+- TrimSegment 数据类（多段裁剪）
+- 常量定义
+"""
+
+from __future__ import annotations
+
+import logging
+from dataclasses import dataclass, field
+from typing import Any
+
+logger = logging.getLogger(__name__)
+
+
+# 最小裁剪时长（秒），低于此值视为无效
+MIN_TRIM_DURATION = 0.1
+
+
+@dataclass
+class TrimConfig:
+    """裁剪配置.
+
+    三选二规则：start_time / end_time / duration 中必须至少给出两个，
+    第三个会被自动推导。如果三个都给了，以 start_time + duration 为准。
+
+    边界保护：
+    - start_time < 0 → 钳制到 0
+    - end_time > 素材时长 → 钳制到素材时长
+    - 计算出的 duration < 最小阈值 → 标记为无效
+    """
+
+    start_time: float = 0.0  # 入点（素材内时间，秒）
+    end_time: float = 0.0  # 出点（素材内时间，秒），0 表示未指定
+    duration: float = 0.0  # 裁剪时长（秒），0 表示未指定
+
+    @classmethod
+    def from_dict(cls, data: dict[str, Any] | None) -> "TrimConfig | None":
+        """从字典构造，无有效裁剪参数时返回 None（不裁剪）."""
+        if not data:
+            return None
+
+        start = float(data.get("start_time", 0) or 0)
+        end = float(data.get("end_time", 0) or 0)
+        dur = float(data.get("duration", 0) or 0)
+
+        # 三个参数都没有 → 不裁剪
+        if start <= 0 and end <= 0 and dur <= 0:
+            return None
+
+        # 至少有两个参数（或一个合理的 start/duration）
+        # 兼容：只传了 start_time → 从 start 开始取到末尾
+        # 兼容：只传了 duration → 从 0 开始取 duration
+        if start > 0 and end <= 0 and dur <= 0:
+            # 只有 start，取到末尾 → 这是"从某点开始"的语义，算有效
+            pass
+        elif dur > 0 and start <= 0 and end <= 0:
+            # 只有 duration → 从开头取 duration，算有效
+            pass
+        elif start <= 0 and end <= 0 and dur <= 0:
+            return None
+
+        return cls(start_time=start, end_time=end, duration=dur)
+
+    def validate_and_resolve(self, asset_duration: float) -> "TrimConfig":
+        """根据素材实际时长，解析并钳制裁剪参数.
+
+        返回一个新的 TrimConfig，其中 start_time / end_time / duration 都已确定。
+        如果裁剪无效（时长为0或负数），仍返回但调用方应检查 is_valid。
+        """
+        start = self.start_time
+        end = self.end_time
+        dur = self.duration
+
+        # 边界：start 不能为负
+        if start < 0:
+            start = 0.0
+
+        # 边界：asset_duration 为 0 时保守处理（不裁剪，取全部）
+        if asset_duration <= 0:
+            return TrimConfig(start_time=0.0, end_time=0.0, duration=0.0)
+
+        # 三选二推导
+        # 判断顺序很重要：先判断需要两个显式值的组合，最后判断含默认值的
+        # 情况1：start + end 都有显式值
+        if start > 0 and end > 0:
+            if end <= start:
+                # 出点 <= 入点，无效 → 返回 start 处一个极短片段（调用方会判无效）
+                return TrimConfig(start_time=start, end_time=start, duration=0.0)
+            dur = end - start
+        # 情况2：end + duration 都有显式值
+        elif end > 0 and dur > 0:
+            start = end - dur
+            if start < 0:
+                start = 0.0
+                dur = end  # 重新计算
+        # 情况3：start + duration 都有值（start 可以是 0）
+        elif dur > 0:
+            end = start + dur
+        # 情况4：只有 start → 取到素材末尾
+        elif start > 0 and end <= 0 and dur <= 0:
+            end = asset_duration
+            dur = end - start
+        # 情况5：只有 end → 从开头取到 end
+        elif end > 0 and start <= 0 and dur <= 0:
+            start = 0.0
+            dur = end
+        else:
+            # 都没有 → 不裁剪
+            return TrimConfig(start_time=0.0, end_time=0.0, duration=0.0)
+
+        # 边界钳制：end 不能超过素材时长
+        if end > asset_duration:
+            end = asset_duration
+            dur = end - start
+
+        # 边界钳制：start 不能超过素材时长
+        if start >= asset_duration:
+            start = max(0.0, asset_duration - MIN_TRIM_DURATION)
+            dur = asset_duration - start
+            end = asset_duration
+
+        # 保证 duration 不为负
+        if dur < 0:
+            dur = 0.0
+
+        return TrimConfig(start_time=start, end_time=end, duration=dur)
+
+    @property
+    def is_valid(self) -> bool:
+        """裁剪是否有效（时长大于最小阈值）."""
+        return self.duration >= MIN_TRIM_DURATION
+
+    @property
+    def is_noop(self) -> bool:
+        """是否等价于不裁剪（从0开始取全部）."""
+        return self.start_time <= 0 and self.duration <= 0
+
+    @property
+    def trim_from_start(self) -> bool:
+        """是否从开头裁剪（start_time == 0）."""
+        return self.start_time <= 0
+
+
+@dataclass
+class TrimSegment:
+    """多段裁剪中的一段."""
+
+    segment_id: str  # 段 ID（用于生成唯一标签）
+    trim: TrimConfig  # 裁剪配置
+    order: int = 0  # 排序
+
+    @classmethod
+    def from_dict(cls, data: dict[str, Any], default_order: int = 0) -> "TrimSegment":
+        """从字典构造."""
+        return cls(
+            segment_id=str(data.get("segment_id", "") or f"seg_{default_order}"),
+            trim=TrimConfig(
+                start_time=float(data.get("start_time", 0) or 0),
+                end_time=float(data.get("end_time", 0) or 0),
+                duration=float(data.get("duration", 0) or 0),
+            ),
+            order=int(data.get("order", default_order)),
+        )
diff --git a/tests/unit/test_trim_config.py b/tests/unit/test_trim_config.py
new file mode 100755
index 000000000..14c8fd3e5
--- /dev/null
+++ b/tests/unit/test_trim_config.py
@@ -0,0 +1,350 @@
+"""裁剪配置领域模型单测 — 纯逻辑，无外部依赖."""
+
+from __future__ import annotations
+
+import pytest
+
+from packages.domain.trim_config import (
+    MIN_TRIM_DURATION,
+    TrimConfig,
+    TrimSegment,
+)
+
+
+# ── 常量 ────────────────────────────────────────────────────────────────────
+
+
+class TestConstants:
+    def test_min_trim_duration_positive(self):
+        assert MIN_TRIM_DURATION > 0
+
+    def test_min_trim_duration_value(self):
+        assert MIN_TRIM_DURATION == 0.1
+
+
+# ── from_dict ──────────────────────────────────────────────────────────────
+
+
+class TestTrimConfigFromDict:
+    def test_none_returns_none(self):
+        assert TrimConfig.from_dict(None) is None
+
+    def test_empty_dict_returns_none(self):
+        assert TrimConfig.from_dict({}) is None
+
+    def test_all_zeros_returns_none(self):
+        assert TrimConfig.from_dict({"start_time": 0, "end_time": 0, "duration": 0}) is None
+
+    def test_start_only_returns_config(self):
+        result = TrimConfig.from_dict({"start_time": 5.0})
+        assert result is not None
+        assert result.start_time == 5.0
+        assert result.end_time == 0
+        assert result.duration == 0
+
+    def test_duration_only_returns_config(self):
+        result = TrimConfig.from_dict({"duration": 3.0})
+        assert result is not None
+        assert result.start_time == 0
+        assert result.end_time == 0
+        assert result.duration == 3.0
+
+    def test_end_only_returns_config(self):
+        # 只有 end_time → from_dict 阶段保留，resolve 时推导为从开头取到 end
+        result = TrimConfig.from_dict({"end_time": 5.0})
+        assert result is not None
+        assert result.end_time == 5.0
+        assert result.start_time == 0
+        assert result.duration == 0
+
+    def test_start_and_duration(self):
+        result = TrimConfig.from_dict({"start_time": 2.0, "duration": 5.0})
+        assert result is not None
+        assert result.start_time == 2.0
+        assert result.duration == 5.0
+
+    def test_start_and_end(self):
+        result = TrimConfig.from_dict({"start_time": 1.0, "end_time": 4.0})
+        assert result is not None
+        assert result.start_time == 1.0
+        assert result.end_time == 4.0
+
+    def test_all_three_params(self):
+        result = TrimConfig.from_dict({"start_time": 1.0, "end_time": 4.0, "duration": 3.0})
+        assert result is not None
+        assert result.start_time == 1.0
+        assert result.end_time == 4.0
+        assert result.duration == 3.0
+
+    def test_string_values_converted(self):
+        result = TrimConfig.from_dict({"start_time": "2.5", "duration": "3.0"})
+        assert result is not None
+        assert result.start_time == 2.5
+        assert result.duration == 3.0
+
+    def test_zero_start_with_duration(self):
+        # start=0 + duration>0 → 有效（从开头取一段）
+        result = TrimConfig.from_dict({"start_time": 0, "duration": 5.0})
+        assert result is not None
+        assert result.start_time == 0
+        assert result.duration == 5.0
+
+    def test_negative_values_treated_as_zero(self):
+        result = TrimConfig.from_dict({"start_time": -1.0, "duration": -2.0})
+        # 两个值都 <= 0 → 返回 None
+        assert result is None
+
+    def test_invalid_type_none_values(self):
+        result = TrimConfig.from_dict({"start_time": None, "duration": None})
+        assert result is None
+
+
+# ── validate_and_resolve: 三选二推导 ──────────────────────────────────────
+
+
+class TestValidateResolve_DeriveDuration:
+    """start + end → 推导 duration."""
+
+    def test_start_end_derive_duration(self):
+        cfg = TrimConfig(start_time=2.0, end_time=5.0)
+        resolved = cfg.validate_and_resolve(asset_duration=10.0)
+        assert resolved.start_time == 2.0
+        assert resolved.end_time == 5.0
+        assert resolved.duration == 3.0
+        assert resolved.is_valid
+
+    def test_start_at_zero_end_derive_duration(self):
+        cfg = TrimConfig(start_time=0.0, end_time=4.0)
+        resolved = cfg.validate_and_resolve(asset_duration=10.0)
+        assert resolved.duration == 4.0
+        assert resolved.start_time == 0.0
+
+    def test_end_equals_start_zero_duration(self):
+        cfg = TrimConfig(start_time=3.0, end_time=3.0)
+        resolved = cfg.validate_and_resolve(asset_duration=10.0)
+        assert resolved.duration == 0.0
+        assert not resolved.is_valid
+
+    def test_end_less_than_start_invalid(self):
+        cfg = TrimConfig(start_time=5.0, end_time=2.0)
+        resolved = cfg.validate_and_resolve(asset_duration=10.0)
+        assert resolved.duration == 0.0
+        assert not resolved.is_valid
+        assert resolved.start_time == 5.0
+
+
+class TestValidateResolve_DeriveEnd:
+    """start + duration → 推导 end."""
+
+    def test_start_duration_derive_end(self):
+        cfg = TrimConfig(start_time=2.0, duration=3.0)
+        resolved = cfg.validate_and_resolve(asset_duration=10.0)
+        assert resolved.start_time == 2.0
+        assert resolved.duration == 3.0
+        assert resolved.end_time == 5.0
+        assert resolved.is_valid
+
+    def test_zero_start_duration_derive_end(self):
+        cfg = TrimConfig(start_time=0.0, duration=5.0)
+        resolved = cfg.validate_and_resolve(asset_duration=10.0)
+        assert resolved.end_time == 5.0
+        assert resolved.duration == 5.0
+
+    def test_start_at_zero_implied(self):
+        # duration > 0, start = 0 → end = duration
+        cfg = TrimConfig(duration=4.0)
+        resolved = cfg.validate_and_resolve(asset_duration=10.0)
+        assert resolved.start_time == 0.0
+        assert resolved.duration == 4.0
+        assert resolved.end_time == 4.0
+
+
+class TestValidateResolve_DeriveStart:
+    """end + duration → 推导 start."""
+
+    def test_end_duration_derive_start(self):
+        cfg = TrimConfig(end_time=8.0, duration=3.0)
+        resolved = cfg.validate_and_resolve(asset_duration=10.0)
+        assert resolved.end_time == 8.0
+        assert resolved.duration == 3.0
+        assert resolved.start_time == 5.0
+        assert resolved.is_valid
+
+    def test_end_duration_start_negative_clamped(self):
+        # end - duration < 0 → start 钳制到 0，duration 重新计算
+        cfg = TrimConfig(end_time=3.0, duration=5.0)
+        resolved = cfg.validate_and_resolve(asset_duration=10.0)
+        assert resolved.start_time == 0.0
+        assert resolved.end_time == 3.0
+        assert resolved.duration == 3.0
+        assert resolved.is_valid
+
+
+class TestValidateResolve_SingleParam:
+    """只有一个参数时的推导."""
+
+    def test_start_only_takes_to_end(self):
+        cfg = TrimConfig(start_time=3.0)
+        resolved = cfg.validate_and_resolve(asset_duration=10.0)
+        assert resolved.start_time == 3.0
+        assert resolved.end_time == 10.0
+        assert resolved.duration == 7.0
+        assert resolved.is_valid
+
+    def test_end_only_takes_from_start(self):
+        cfg = TrimConfig(end_time=5.0)
+        resolved = cfg.validate_and_resolve(asset_duration=10.0)
+        assert resolved.start_time == 0.0
+        assert resolved.end_time == 5.0
+        assert resolved.duration == 5.0
+        assert resolved.is_valid
+
+    def test_duration_only_from_start(self):
+        cfg = TrimConfig(duration=4.0)
+        resolved = cfg.validate_and_resolve(asset_duration=10.0)
+        assert resolved.start_time == 0.0
+        assert resolved.end_time == 4.0
+        assert resolved.duration == 4.0
+
+
+class TestValidateResolve_BoundaryClamp:
+    """边界钳制测试."""
+
+    def test_end_exceeds_asset_duration(self):
+        cfg = TrimConfig(start_time=2.0, duration=20.0)
+        resolved = cfg.validate_and_resolve(asset_duration=10.0)
+        assert resolved.end_time == 10.0
+        assert resolved.duration == 8.0
+        assert resolved.is_valid
+
+    def test_start_exceeds_asset_duration(self):
+        cfg = TrimConfig(start_time=15.0)
+        resolved = cfg.validate_and_resolve(asset_duration=10.0)
+        # start >= asset_duration → 钳制到末尾附近
+        assert resolved.start_time <= 10.0
+        assert resolved.end_time == 10.0
+        assert resolved.duration == pytest.approx(MIN_TRIM_DURATION, abs=0.001)
+
+    def test_negative_start_clamped(self):
+        cfg = TrimConfig(start_time=-2.0, duration=5.0)
+        resolved = cfg.validate_and_resolve(asset_duration=10.0)
+        assert resolved.start_time == 0.0
+        assert resolved.duration == 5.0
+        assert resolved.end_time == 5.0
+
+    def test_negative_start_with_end(self):
+        cfg = TrimConfig(start_time=-1.0, end_time=4.0)
+        resolved = cfg.validate_and_resolve(asset_duration=10.0)
+        assert resolved.start_time == 0.0
+        assert resolved.end_time == 4.0
+        assert resolved.duration == 4.0
+
+    def test_asset_duration_zero_returns_noop(self):
+        cfg = TrimConfig(start_time=1.0, duration=2.0)
+        resolved = cfg.validate_and_resolve(asset_duration=0.0)
+        assert resolved.start_time == 0.0
+        assert resolved.duration == 0.0
+        assert not resolved.is_valid
+
+    def test_asset_duration_negative_returns_noop(self):
+        cfg = TrimConfig(start_time=1.0, duration=2.0)
+        resolved = cfg.validate_and_resolve(asset_duration=-5.0)
+        assert resolved.start_time == 0.0
+        assert resolved.duration == 0.0
+
+    def test_no_params_returns_noop(self):
+        cfg = TrimConfig()
+        resolved = cfg.validate_and_resolve(asset_duration=10.0)
+        assert resolved.start_time == 0.0
+        assert resolved.duration == 0.0
+        assert resolved.is_noop
+
+
+# ── 属性判断 ────────────────────────────────────────────────────────────────
+
+
+class TestTrimConfigProperties:
+    def test_is_valid_true(self):
+        cfg = TrimConfig(start_time=1.0, end_time=3.0, duration=2.0)
+        assert cfg.is_valid
+
+    def test_is_valid_zero_duration(self):
+        cfg = TrimConfig(duration=0.0)
+        assert not cfg.is_valid
+
+    def test_is_valid_below_min(self):
+        cfg = TrimConfig(duration=MIN_TRIM_DURATION / 2)
+        assert not cfg.is_valid
+
+    def test_is_valid_exact_min(self):
+        cfg = TrimConfig(duration=MIN_TRIM_DURATION)
+        assert cfg.is_valid
+
+    def test_is_noop_true(self):
+        cfg = TrimConfig()
+        assert cfg.is_noop
+
+    def test_is_noop_false_with_start(self):
+        cfg = TrimConfig(start_time=1.0)
+        assert not cfg.is_noop
+
+    def test_is_noop_false_with_duration(self):
+        cfg = TrimConfig(duration=1.0)
+        assert not cfg.is_noop
+
+    def test_trim_from_start_true(self):
+        cfg = TrimConfig(duration=3.0)
+        assert cfg.trim_from_start
+
+    def test_trim_from_start_false(self):
+        cfg = TrimConfig(start_time=2.0, duration=3.0)
+        assert not cfg.trim_from_start
+
+    def test_trim_from_start_zero_start(self):
+        cfg = TrimConfig(start_time=0.0, duration=3.0)
+        assert cfg.trim_from_start
+
+
+# ── TrimSegment ────────────────────────────────────────────────────────────
+
+
+class TestTrimSegment:
+    def test_from_dict_basic(self):
+        seg = TrimSegment.from_dict({
+            "segment_id": "seg1",
+            "start_time": 1.0,
+            "end_time": 4.0,
+            "order": 0,
+        })
+        assert seg.segment_id == "seg1"
+        assert seg.trim.start_time == 1.0
+        assert seg.trim.end_time == 4.0
+        assert seg.order == 0
+
+    def test_from_dict_default_order(self):
+        seg = TrimSegment.from_dict({"segment_id": "seg1"}, default_order=3)
+        assert seg.order == 3
+
+    def test_from_dict_order_overrides_default(self):
+        seg = TrimSegment.from_dict({"segment_id": "seg1", "order": 5}, default_order=3)
+        assert seg.order == 5
+
+    def test_from_dict_default_segment_id(self):
+        seg = TrimSegment.from_dict({}, default_order=2)
+        assert seg.segment_id == "seg_2"
+
+    def test_from_dict_empty_segment_id_fallback(self):
+        seg = TrimSegment.from_dict({"segment_id": ""}, default_order=0)
+        assert seg.segment_id == "seg_0"
+
+    def test_from_dict_duration_only(self):
+        seg = TrimSegment.from_dict({"segment_id": "s1", "duration": 5.0})
+        assert seg.trim.duration == 5.0
+        assert seg.trim.start_time == 0.0
+
+    def test_trim_segment_dataclass_fields(self):
+        cfg = TrimConfig(start_time=1.0, duration=2.0)
+        seg = TrimSegment(segment_id="s1", trim=cfg, order=2)
+        assert seg.segment_id == "s1"
+        assert seg.trim is cfg
+        assert seg.order == 2