diff --git a/backend/agent/skills/cad-engine/SKILL.md b/backend/agent/skills/cad-engine/SKILL.md
index 9427d021..234460ee 100644
--- a/backend/agent/skills/cad-engine/SKILL.md
+++ b/backend/agent/skills/cad-engine/SKILL.md
@@ -51,3 +51,16 @@ Help an AI agent generate CAD models through the repository's CDSL engine.
   value shapes in `cdsl_schema.json`. In particular, hole positions must be
   objects such as `{"mm": [u_mm, v_mm, w_mm]}`, never bare coordinate arrays.
 - Preserve the original CDSL and write revisions as separate artifacts.
+
+## CADFS Engine Maintenance
+
+When changing CADFS lowering, the CDSL schema, runtime, geometry adapter,
+selector binding, or their tests, update
+`cadfs_to_cdsl/ENGINE_CAPABILITY_GAPS_PROGRESS.local.md` in the same change.
+
+- Record the end-to-end capability state, remaining semantic boundary, and
+  regression evidence. A successful rebuild is not geometric similarity.
+- Update a capability to completed only when lowering, contract, execution,
+  geometry, and regression coverage all exist.
+- The progress ledger is local development state and is intentionally ignored
+  by Git. Do not add it to a commit.
diff --git a/backend/agent/skills/cdsl-author-guidance/manifest.json b/backend/agent/skills/cdsl-author-guidance/manifest.json
index 74d07eff..f82f8911 100644
--- a/backend/agent/skills/cdsl-author-guidance/manifest.json
+++ b/backend/agent/skills/cdsl-author-guidance/manifest.json
@@ -15,12 +15,15 @@
     {"id": "10-repair-and-best-effort", "file": "10-repair-and-best-effort.md", "title": "10 Repair And Best Effort", "priority": 80, "mandatory": false},
     {"id": "op-extrude-add", "file": "op-extrude-add.md", "title": "Operation Appendix Extrude Add", "priority": 100, "mandatory": true},
     {"id": "op-extrude-cut", "file": "op-extrude-cut.md", "title": "Operation Appendix Extrude Cut", "priority": 100, "mandatory": true},
+    {"id": "op-loft", "file": "op-loft.md", "title": "Operation Appendix Loft", "priority": 100, "mandatory": true},
     {"id": "op-revolve", "file": "op-revolve.md", "title": "Operation Appendix Revolve", "priority": 100, "mandatory": true},
     {"id": "op-hole", "file": "op-hole.md", "title": "Operation Appendix Hole", "priority": 100, "mandatory": true},
     {"id": "op-reference", "file": "op-reference.md", "title": "Operation Appendix Reference", "priority": 100, "mandatory": true},
     {"id": "op-pattern", "file": "op-pattern.md", "title": "Operation Appendix Pattern", "priority": 100, "mandatory": true},
     {"id": "op-finish", "file": "op-finish.md", "title": "Operation Appendix Finish", "priority": 100, "mandatory": true},
-    {"id": "op-sphere", "file": "op-sphere.md", "title": "Operation Appendix Sphere", "priority": 100, "mandatory": true}
+    {"id": "op-sphere", "file": "op-sphere.md", "title": "Operation Appendix Sphere", "priority": 100, "mandatory": true},
+    {"id": "op-primitives", "file": "op-primitives.md", "title": "Operation Appendix Primitives", "priority": 100, "mandatory": true},
+    {"id": "op-thread", "file": "op-thread.md", "title": "Operation Appendix Thread", "priority": 100, "mandatory": true}
   ],
   "phase_sections": {
     "DEFAULT": ["00-author-contract", "03-coordinate-system-and-datums", "09-evidence-visual-review-and-validation"],
@@ -39,6 +42,9 @@
     "extrude_add_blind": ["op-extrude-add"],
     "extrude_add_two_sided": ["op-extrude-add"],
     "extrude_cut_blind": ["op-extrude-cut"],
+    "extrude_cut_two_sided": ["op-extrude-cut"],
+    "extrude_cut_through": ["op-extrude-cut"],
+    "loft_add": ["op-loft"],
     "revolve_add": ["op-revolve"],
     "revolve_cut": ["op-revolve"],
     "hole_blind": ["op-hole"],
@@ -49,8 +55,13 @@
     "reference_axis": ["op-reference"],
     "pattern_linear": ["op-pattern"],
     "pattern_mirror": ["op-pattern"],
+    "pattern_circular": ["op-pattern"],
     "fillet": ["op-finish"],
     "chamfer": ["op-finish"],
-    "sphere_add": ["op-sphere"]
+    "sphere_add": ["op-sphere"],
+    "box_add": ["op-primitives"],
+    "cylinder_add": ["op-primitives"],
+    "thread_add": ["op-thread"],
+    "thread_cut": ["op-thread"]
   }
 }
diff --git a/backend/agent/skills/cdsl-author-guidance/op-extrude-cut.md b/backend/agent/skills/cdsl-author-guidance/op-extrude-cut.md
index 960bca12..f88a19b2 100644
--- a/backend/agent/skills/cdsl-author-guidance/op-extrude-cut.md
+++ b/backend/agent/skills/cdsl-author-guidance/op-extrude-cut.md
@@ -1 +1 @@
-`extrude_cut_blind` 使用闭合草图、当前允许的正距离和正确宿主 frame。从实际材料面进入，方向由 workplane normal 与 contract 的 `reverse` 决定；深度应覆盖目标材料，不能刚好停在共面边界。切除失败时先检查轮廓、宿主、方向、深度和材料覆盖，而不是盲目加大距离。
+`extrude_cut_blind` 使用闭合草图、当前允许的正距离和正确宿主 frame。从实际材料面进入，方向由 workplane normal 与 contract 的 `reverse` 决定；深度应覆盖目标材料，不能刚好停在共面边界。`extrude_cut_two_sided` 必须分别提供正向和反向的距离与终止条件，不能以单侧深度近似双向切除。`extrude_cut_through` 只接受明确的 `end_condition`，由现有主体跨度决定穿透距离，不能伪造盲向深度。切除失败时先检查轮廓、宿主、方向、深度和材料覆盖，而不是盲目加大距离。
diff --git a/backend/agent/skills/cdsl-author-guidance/op-loft.md b/backend/agent/skills/cdsl-author-guidance/op-loft.md
new file mode 100644
index 00000000..99deb7c9
--- /dev/null
+++ b/backend/agent/skills/cdsl-author-guidance/op-loft.md
@@ -0,0 +1 @@
+`loft_add` 在 `params.profile_sketch_ids` 中按放样方向列出至少两条不同的闭合草图。每条截面必须解析为一条无孔外轮廓；截面拓扑和 workplane frame 必须稳定对应。不要以挤出替代放样，也不要把 selector 选中的实体面当作放样截面，除非 operation contract 明确支持。
diff --git a/backend/agent/skills/cdsl-author-guidance/op-primitives.md b/backend/agent/skills/cdsl-author-guidance/op-primitives.md
new file mode 100644
index 00000000..09e10d85
--- /dev/null
+++ b/backend/agent/skills/cdsl-author-guidance/op-primitives.md
@@ -0,0 +1 @@
+`box_add` 和 `cylinder_add` 是世界坐标原生图元。按 operation contract 提供正尺寸以及明确的 `center_mm` 或 axis。仅在目标确为长方体或圆柱体时使用；由轮廓驱动的几何保留草图、放样等历史表达。
diff --git a/backend/agent/skills/cdsl-author-guidance/op-thread.md b/backend/agent/skills/cdsl-author-guidance/op-thread.md
new file mode 100644
index 00000000..38e932da
--- /dev/null
+++ b/backend/agent/skills/cdsl-author-guidance/op-thread.md
@@ -0,0 +1 @@
+`thread_add` 和 `thread_cut` 需要明确的 axis、正的大小径、螺距和长度，且各参数必须物理一致。螺纹切除必须有已有宿主实体；需求为实体螺纹时，不能以光滑孔替代。
diff --git a/backend/engine/cdsl_engine/build123d_adapter.py b/backend/engine/cdsl_engine/build123d_adapter.py
index 105ba1b3..e555705e 100644
--- a/backend/engine/cdsl_engine/build123d_adapter.py
+++ b/backend/engine/cdsl_engine/build123d_adapter.py
@@ -65,9 +65,15 @@ class Build123dGeometryAdapter:
 
     @staticmethod
     def _wire(edges: list[dict[str, Any]]) -> Wire:
-        # 将边字典列表（直线/圆弧）组装成 build123d 的 Wire 线框。
+        # 将边字典列表（直线/圆弧/插值 B 样条）组装成 build123d 的 Wire 线框。
         built: list[Edge] = []
         for edge in edges:
+            if edge.get("type") == "bspline":
+                points = [_vector(point) for point in edge.get("points_mm") or []]
+                if len(points) < 3:
+                    raise ValueError("bspline contour edge needs at least 3 points")
+                built.append(Edge.make_spline(points, periodic=False))
+                continue
             start = _vector(edge["start_mm"])
             end = _vector(edge["end_mm"])
             if edge.get("type") == "arc" and edge.get("center_mm") is not None:
@@ -133,20 +139,38 @@ class Build123dGeometryAdapter:
             result: list[Face] = []
             for region in regions:
                 outer = region.get("outer") or []
-                if len(outer) < 2:
+                # 闭合插值样条仅有一条边；直线/圆弧轮廓通常由多条边组成。
+                if len(outer) < 1:
                     continue
                 face = Face(self._wire(outer))
-                holes = [self._wire(hole) for hole in region.get("holes") or [] if len(hole) >= 2]
+                holes = [self._wire(hole) for hole in region.get("holes") or [] if len(hole) >= 1]
                 result.append(face.make_holes(holes) if holes else face)
             return result
         # 2. 退化：仅有单组轮廓边时，直接作为外轮廓建面。
         edges = sketch.get("contour_edges_mm") or []
-        if len(edges) >= 2:
+        if len(edges) >= 1:
             return [Face(self._wire(edges))]
         # 3. 最终回退：由工作平面与实体圆生成面（圆环/孔洞处理见 _faces_from_circles）。
         plane = PlaneSpec.from_mapping(sketch.get("workplane") or {})
         return self._faces_from_circles(sketch.get("entities") or [], plane)
 
+    def loft(self, sketches: list[dict[str, Any]]) -> Solid:
+        """由多条简单闭合草图轮廓生成实体放样。"""
+        wires: list[Wire] = []
+        for index, sketch in enumerate(sketches):
+            # Solid.make_loft 接收 Wire；复用 faces_for_sketch 保持放样、
+            # 拉伸和回转的 profile resolver 一致。多区域/内环的截面对应关系
+            # 尚未由 CDSL 表达，必须显式拒绝而非猜测。
+            faces = self.faces_for_sketch(sketch)
+            if len(faces) != 1:
+                raise ValueError(f"loft profile {index} must resolve to exactly one closed region")
+            if faces[0].inner_wires():
+                raise ValueError(f"loft profile {index} must not contain inner loops")
+            wires.append(faces[0].outer_wire())
+        if len(wires) < 2:
+            raise ValueError("loft requires at least two profile sketches")
+        return Solid.make_loft(wires)
+
     @staticmethod
     def _coerce_single_or_compound(result: Any, *, empty_error: str | None = None) -> Any:
         """规整一次布尔结果：None/空视为失败（可选报错），多成员合并为 Compound。"""
@@ -188,14 +212,22 @@ class Build123dGeometryAdapter:
         """
         # 1. 采样点到目标的最远命中距离决定穿透余量；没有任何采样点命中
         #    说明 profile 与目标面无交叠，无法裁剪（保留 extent_target_not_reached）。
+        #    through_next 的 target 是当前主体，必须先从其面中选出实际命中的
+        #    下一终止面，不能把整个 body 当作待拉伸的 Face。
         unit = _vector(direction).normalized()
-        hits = [
-            Build123dGeometryAdapter._forward_intersection_distance(target, point, unit)
-            for point in Build123dGeometryAdapter.profile_sample_points(face)
-        ]
-        distances = [value for value in hits if value is not None]
-        if not distances:
+        points = Build123dGeometryAdapter.profile_sample_points(face)
+        targets = [target] if isinstance(target, Face) else list(target.faces())
+        candidates = []
+        for candidate in targets:
+            hits = [Build123dGeometryAdapter._forward_intersection_distance(candidate, point, unit) for point in points]
+            distances = [value for value in hits if value is not None]
+            if distances:
+                candidates.append((len(distances), min(distances), candidate, distances))
+        if not candidates:
             raise ValueError("extent target is not reached by the profile")
+        # 覆盖最多 profile 采样点的面就是本次实体的下一终止面；覆盖数相同
+        # 时取最近的正向交点，确保相邻面交界处的选择稳定。
+        _, _, target, distances = max(candidates, key=lambda item: (item[0], -item[1]))
         margin = max(distances) + 2.0
         # 2. 穿透拉伸 profile，同时把目标面向回推生成体层，二者求交即裁剪体。
         #    build123d 的布尔交方法名是 intersect（不是 OCC 的 common），
diff --git a/backend/engine/cdsl_engine/capabilities.py b/backend/engine/cdsl_engine/capabilities.py
index dd023cc7..6ad669aa 100644
--- a/backend/engine/cdsl_engine/capabilities.py
+++ b/backend/engine/cdsl_engine/capabilities.py
@@ -22,21 +22,22 @@ _SKETCH_ATOM_PREFIXES = ("extrude_", "revolve_")
 # 物理意义：仅 extrude 直切类原子支持；add/回转对开放轮廓会造出无意义的封块。
 _OPEN_PROFILE_ATOMICS = frozenset({"extrude_cut_blind", "extrude_cut_through"})
 _PRIMARY_ATOMICS = frozenset({
-    "extrude_add_blind", "extrude_add_two_sided", "extrude_cut_blind",
+    "extrude_add_blind", "extrude_add_two_sided", "extrude_cut_blind", "extrude_cut_two_sided",
     "extrude_cut_through",
     "revolve_add", "revolve_cut", "hole_blind", "hole_countersink",
     "hole_counterbore", "sphere_add", "box_add", "cylinder_add",
 })
 _HOLE_ATOMICS = frozenset({"hole_blind", "hole_countersink", "hole_counterbore", "hole_wizard"})
 _ACTIVE_BODY_REQUIRED = frozenset({
-    "extrude_cut_blind", "extrude_cut_through", "revolve_cut", *_HOLE_ATOMICS, "fillet", "chamfer",
+    "extrude_cut_blind", "extrude_cut_two_sided", "extrude_cut_through",
+    "revolve_cut", *_HOLE_ATOMICS, "fillet", "chamfer",
     # thread_cut 是 cut 型特征：必须在已有主体（宿主）上做布尔差，不能凭空
     # 造实体；无宿主时按 active_body 前置阻止而非让 executor 在 None 上崩溃。
     "thread_cut",
 })
 _BODY_MUTATING_ATOMICS = frozenset({
-    "extrude_add_blind", "extrude_add_two_sided", "extrude_cut_blind",
-    "extrude_cut_through",
+    "extrude_add_blind", "extrude_add_two_sided", "extrude_cut_blind", "extrude_cut_two_sided",
+    "extrude_cut_through", "loft_add",
     "revolve_add", "revolve_cut", "sphere_add", "box_add", "cylinder_add",
     "thread_add", "thread_cut", *_HOLE_ATOMICS, "fillet", "chamfer",
 })
@@ -148,27 +149,32 @@ def _schema_contract() -> dict[str, dict[str, Any]]:
 
 
 def sketch_ids_required_by_contract(cdsl: dict[str, Any]) -> frozenset[str]:
-    """Return only sketches consumed by a feature with a sketch contract.
+    """Return only sketches consumed by executable feature contracts.
 
     CAD documents commonly preserve construction or abandoned sketches whose
     contours are incomplete.  They are semantic data, but must not make an
-    otherwise independent feature history ineligible for execution.
+    otherwise independent feature history ineligible for execution.  Most
+    operations declare ``sketch_id``; loft declares its ordered section set
+    in ``params.profile_sketch_ids``.
     """
     contracts = _schema_contract()
-    return frozenset(
-        str(feature["sketch_id"])
-        for feature in cdsl.get("features") or ()
-        if feature.get("sketch_id") is not None
-        and (contracts.get(str(feature.get("atomic_id") or "")) or {}).get("requires_sketch")
-    )
+    required: set[str] = set()
+    for feature in cdsl.get("features") or ():
+        atomic_id = str(feature.get("atomic_id") or "")
+        if feature.get("sketch_id") is not None and (contracts.get(atomic_id) or {}).get("requires_sketch"):
+            required.add(str(feature["sketch_id"]))
+        if atomic_id == "loft_add":
+            for sketch_id in (feature.get("params") or {}).get("profile_sketch_ids") or ():
+                required.add(str(sketch_id))
+    return frozenset(required)
 
 
 def _has_closed_region(sketch: dict[str, Any]) -> bool:
     """Mirror the adapter's input contract without importing the geometry kernel."""
     regions = sketch.get("contour_regions_mm") or []
-    if any(len(region.get("outer") or []) >= 2 for region in regions if isinstance(region, dict)):
+    if any(len(region.get("outer") or []) >= 1 for region in regions if isinstance(region, dict)):
         return True
-    if len(sketch.get("contour_edges_mm") or []) >= 2:
+    if len(sketch.get("contour_edges_mm") or []) >= 1:
         return True
     return any(
         entity.get("type") == "circle" and not entity.get("construction")
@@ -178,6 +184,18 @@ def _has_closed_region(sketch: dict[str, Any]) -> bool:
     )
 
 
+def _has_single_loft_region(sketch: dict[str, Any]) -> bool:
+    """Whether a resolved profile maps exactly to one solid loft section."""
+    regions = sketch.get("contour_regions_mm") or []
+    if regions:
+        return len(regions) == 1 and not (regions[0].get("holes") or [])
+    circles = [
+        entity for entity in sketch.get("entities") or []
+        if isinstance(entity, dict) and entity.get("type") == "circle" and not entity.get("construction")
+    ]
+    return len(circles) == 1
+
+
 @dataclass(frozen=True)
 class CapabilityAnalysis:
     plan: tuple[FeaturePlanNode, ...]
@@ -295,6 +313,54 @@ class CapabilityAnalyzer:
                                 sketch_id=node.sketch_id,
                                 atomic_id=node.atomic_id,
                             ))
+                if node.atomic_id == "loft_add":
+                    profile_ids = params.get("profile_sketch_ids")
+                    if not isinstance(profile_ids, list) or len(profile_ids) < 2:
+                        blockers.append(self._blocker(
+                            node.feature_id, "invalid_loft_profiles",
+                            "Loft requires at least two profile sketch ids",
+                        ))
+                    elif len({str(sketch_id) for sketch_id in profile_ids}) != len(profile_ids):
+                        blockers.append(self._blocker(
+                            node.feature_id, "invalid_loft_profiles",
+                            "Loft profile sketch ids must be distinct",
+                        ))
+                    else:
+                        for sketch_id in profile_ids:
+                            sketch_id = str(sketch_id)
+                            profile = sketches.get(sketch_id)
+                            if profile is None:
+                                blockers.append(self._blocker(
+                                    node.feature_id, "missing_loft_profile",
+                                    "Loft profile sketch does not exist", sketch_id=sketch_id,
+                                ))
+                                continue
+                            profile_type = str((profile.get("profile") or {}).get("type") or "")
+                            required.append(f"loft_profile:{profile_type}")
+                            resolution_error = sketch_errors.get(sketch_id)
+                            if resolution_error:
+                                blockers.append(self._blocker(
+                                    node.feature_id, "profile_resolution_failed",
+                                    "A loft profile sketch could not be resolved into executable regions",
+                                    sketch_id=sketch_id, reason=resolution_error,
+                                ))
+                            elif profile_type not in self.profile_types:
+                                blockers.append(self._blocker(
+                                    node.feature_id, "unsupported_profile",
+                                    "The current runtime cannot resolve a loft profile",
+                                    sketch_id=sketch_id, profile_type=profile_type,
+                                ))
+                            elif not _has_closed_region(profile):
+                                blockers.append(self._blocker(
+                                    node.feature_id, "profile_no_closed_region",
+                                    "A loft profile contains no closed region", sketch_id=sketch_id,
+                                ))
+                            elif not _has_single_loft_region(profile):
+                                blockers.append(self._blocker(
+                                    node.feature_id, "unsupported_loft_profile_regions",
+                                    "Loft currently requires exactly one outer profile without holes",
+                                    sketch_id=sketch_id,
+                                ))
             if node.atomic_id.startswith(_SKETCH_ATOM_PREFIXES):
                 # #2 draft：extrudeParams.draft 在 cdsl_schema.json 中被允许，
                 # 但 runtime 的拉伸执行器（build123d Solid.extrude）没有锥形
@@ -332,7 +398,7 @@ class CapabilityAnalyzer:
                             node.feature_id, "missing_offset_distance",
                             "Offset-from-surface requires a non-zero captured offset distance",
                         ))
-                if node.atomic_id == "extrude_add_two_sided":
+                if node.atomic_id in {"extrude_add_two_sided", "extrude_cut_two_sided"}:
                     reverse_condition = params.get("reverse_end_condition") or {"type": "blind"}
                     reverse_type = reverse_condition.get("type")
                     required.append(f"extent:reverse:{reverse_type}")
@@ -463,7 +529,8 @@ class CapabilityAnalyzer:
                 if node.atomic_id in _BODY_MUTATING_ATOMICS:
                     body_available = True
         body_producers = {
-            "extrude_add_blind", "extrude_add_two_sided", "extrude_cut_blind",
+            "extrude_add_blind", "extrude_add_two_sided", "extrude_cut_blind", "extrude_cut_two_sided",
+            "extrude_cut_through", "loft_add",
             "revolve_add", "revolve_cut", "sphere_add", "box_add", "cylinder_add",
             "thread_add",
             # thread_cut 与 extrude_cut_blind/revolve_cut 一致：无宿主时由
diff --git a/backend/engine/cdsl_engine/cdsl_schema.json b/backend/engine/cdsl_engine/cdsl_schema.json
index 6f251c8e..c8774d56 100644
--- a/backend/engine/cdsl_engine/cdsl_schema.json
+++ b/backend/engine/cdsl_engine/cdsl_schema.json
@@ -108,6 +108,20 @@
       "required": ["end_condition"],
       "additionalProperties": false
     },
+    "loftParams": {
+      "type": "object",
+      "properties": {
+        "profile_sketch_ids": {
+          "type": "array",
+          "minItems": 2,
+          "maxItems": 16,
+          "uniqueItems": true,
+          "items": {"type": "string", "pattern": "^[A-Za-z0-9_-]{1,80}$"}
+        }
+      },
+      "required": ["profile_sketch_ids"],
+      "additionalProperties": false
+    },
     "revolveParams": {
       "type": "object",
       "properties": {"angle_deg": {"type": "number", "minimum": 0, "maximum": 360}, "axis": {"$ref": "#/$defs/axis"}, "reverse": {"type": "boolean"}, "end_condition": {"$ref": "#/$defs/endCondition"}},
@@ -335,18 +349,20 @@
     "analyticSegment": {
       "type": "object",
       "properties": {
-        "type": {"enum": ["line", "arc", "circle"]},
+        "type": {"enum": ["line", "arc", "circle", "bspline"]},
         "start": {"$ref": "#/$defs/point2"},
         "end": {"$ref": "#/$defs/point2"},
         "center": {"$ref": "#/$defs/point2"},
         "radius_mm": {"$ref": "#/$defs/positive"},
+        "points": {"type": "array", "minItems": 3, "items": {"$ref": "#/$defs/point2"}},
         "clockwise": {"type": "boolean"}
       },
       "required": ["type"],
       "allOf": [
         {"if": {"properties": {"type": {"const": "line"}}}, "then": {"required": ["start", "end"]}},
         {"if": {"properties": {"type": {"const": "arc"}}}, "then": {"required": ["start", "end", "center", "radius_mm"]}},
-        {"if": {"properties": {"type": {"const": "circle"}}}, "then": {"required": ["center", "radius_mm"]}}
+        {"if": {"properties": {"type": {"const": "circle"}}}, "then": {"required": ["center", "radius_mm"]}},
+        {"if": {"properties": {"type": {"const": "bspline"}}}, "then": {"required": ["start", "end", "points"]}}
       ],
       "additionalProperties": false
     },
@@ -389,7 +405,7 @@
       "required": ["type", "contours"],
       "additionalProperties": false
     },
-    "feature_atomic_ids": {"enum": ["extrude_add_blind", "extrude_add_two_sided", "extrude_cut_blind", "extrude_cut_through", "revolve_add", "revolve_cut", "hole_blind", "hole_countersink", "hole_counterbore", "sphere_add", "box_add", "cylinder_add", "thread_add", "thread_cut", "fillet", "chamfer", "pattern_linear", "pattern_mirror", "pattern_circular", "reference_plane", "reference_axis", "hole_wizard"]},
+    "feature_atomic_ids": {"enum": ["extrude_add_blind", "extrude_add_two_sided", "extrude_cut_blind", "extrude_cut_two_sided", "extrude_cut_through", "loft_add", "revolve_add", "revolve_cut", "hole_blind", "hole_countersink", "hole_counterbore", "sphere_add", "box_add", "cylinder_add", "thread_add", "thread_cut", "fillet", "chamfer", "pattern_linear", "pattern_mirror", "pattern_circular", "reference_plane", "reference_axis", "hole_wizard"]},
     "feature": {
       "type": "object",
       "properties": {
@@ -410,6 +426,8 @@
         {"if": {"properties": {"atomic_id": {"const": "extrude_add_two_sided"}}}, "then": {"properties": {"params": {"$ref": "#/$defs/extrudeParams"}}}},
         {"if": {"properties": {"atomic_id": {"const": "extrude_cut_blind"}}}, "then": {"properties": {"params": {"$ref": "#/$defs/extrudeParams"}}}},
         {"if": {"properties": {"atomic_id": {"const": "extrude_cut_through"}}}, "then": {"properties": {"params": {"$ref": "#/$defs/extrudeCutThroughParams"}}}},
+        {"if": {"properties": {"atomic_id": {"const": "extrude_cut_two_sided"}}}, "then": {"properties": {"params": {"$ref": "#/$defs/extrudeParams"}}}},
+        {"if": {"properties": {"atomic_id": {"const": "loft_add"}}}, "then": {"properties": {"params": {"$ref": "#/$defs/loftParams"}}}},
         {"if": {"properties": {"atomic_id": {"const": "revolve_add"}}}, "then": {"properties": {"params": {"$ref": "#/$defs/revolveParams"}}}},
         {"if": {"properties": {"atomic_id": {"const": "revolve_cut"}}}, "then": {"properties": {"params": {"$ref": "#/$defs/revolveParams"}}}},
         {"if": {"properties": {"atomic_id": {"const": "sphere_add"}}}, "then": {"properties": {"params": {"$ref": "#/$defs/sphereParams"}}}},
diff --git a/backend/engine/cdsl_engine/phase_pools.py b/backend/engine/cdsl_engine/phase_pools.py
index 7e274f06..83a5dd5c 100644
--- a/backend/engine/cdsl_engine/phase_pools.py
+++ b/backend/engine/cdsl_engine/phase_pools.py
@@ -18,7 +18,7 @@ from .sketch_solver import resolve_required_sketches
 
 P3_ATOMIC_IDS = frozenset({
     "reference_plane", "reference_axis", "extrude_add_blind", "extrude_add_two_sided",
-    "extrude_cut_blind", "revolve_add", "revolve_cut",
+    "extrude_cut_blind", "extrude_cut_two_sided", "revolve_add", "revolve_cut",
 })
 P4_ATOMIC_IDS = P3_ATOMIC_IDS | frozenset({"hole_wizard"})
 P6_ATOMIC_IDS = P4_ATOMIC_IDS | frozenset({"pattern_linear", "pattern_mirror"})
@@ -27,7 +27,7 @@ P3_PROFILE_TYPES = frozenset({"analytic_contours", "circle", "polygon"})
 # revolve history.  Whether a first cut has a preceding active body remains a
 # runtime preflight question, not a reason to erase it from the input pool.
 _P3_PRIMARY_ATOMICS = frozenset({
-    "extrude_add_blind", "extrude_add_two_sided", "extrude_cut_blind", "revolve_add", "revolve_cut",
+    "extrude_add_blind", "extrude_add_two_sided", "extrude_cut_blind", "extrude_cut_two_sided", "revolve_add", "revolve_cut",
 })
 
 
@@ -47,8 +47,8 @@ def _p3_profile_ready(cdsl: dict[str, Any]) -> bool:
         if profile.get("type") not in P3_PROFILE_TYPES:
             return False
         if not (
-            any(len(region.get("outer") or []) >= 2 for region in sketch.get("contour_regions_mm") or () if isinstance(region, dict))
-            or len(sketch.get("contour_edges_mm") or ()) >= 2
+            any(len(region.get("outer") or []) >= 1 for region in sketch.get("contour_regions_mm") or () if isinstance(region, dict))
+            or len(sketch.get("contour_edges_mm") or ()) >= 1
             or any(
                 entity.get("type") == "circle" and not entity.get("construction") and float(entity.get("radius_mm") or 0.0) > 0
                 for entity in sketch.get("entities") or ()
diff --git a/backend/engine/cdsl_engine/profile_schema.json b/backend/engine/cdsl_engine/profile_schema.json
index 4a38cba6..6afb7565 100644
--- a/backend/engine/cdsl_engine/profile_schema.json
+++ b/backend/engine/cdsl_engine/profile_schema.json
@@ -1,15 +1,17 @@
 {
   "schema": "cdsl.engine.schema.v1",
-  "schema_version": "1.3.1",
+  "schema_version": "1.3.2",
   "cdsl_json_schema_file": "cdsl_schema.json",
   "maintenance_rule": "The CDSL-only runtime contract is limited to direct generic profiles and runtime.py EXECUTORS. Legacy macro profiles are importer compatibility syntax and must be lowered by cdsl_importer.legacy_profile_adapter before generic runtime validation.",
   "coordinate_convention": "All profile dimensions use millimetres. Two-dimensional points are [u, v] in the sketch workplane.",
   "runtime_supported_profiles": ["circle", "polygon", "analytic_contours"],
   "operation_contracts": {
     "extrude_add_blind": {"atomic_id":"extrude_add_blind","contract_version":"3.0","fragment_shape":{"sketch":"required","params":"required_object","selector_tokens":"forbidden"},"author_params_schema":{"type":"object","properties":{"distance_mm":{"type":"number","exclusiveMinimum":0},"reverse":{"type":"boolean"}},"required":["distance_mm"],"additionalProperties":false},"selector_policy":{"slot":null,"token_kind":null,"min_items":0,"max_items":0,"snapshot_bound":false},"server_injected_paths":[],"reference_policy":{"mode":"none"},"semantic_preflight":["sketch_workplane","profile_non_self_intersecting"],"candidate_verifiers":["single_connected_body"]},
+    "loft_add": {"atomic_id":"loft_add","contract_version":"3.0","fragment_shape":{"sketch":"forbidden","params":"required_object","selector_tokens":"forbidden"},"author_params_schema":{"type":"object","properties":{"profile_sketch_ids":{"type":"array","items":{"type":"string","pattern":"^[A-Za-z0-9_-]{1,80}$"},"minItems":2,"maxItems":16,"uniqueItems":true}},"required":["profile_sketch_ids"],"additionalProperties":false},"selector_policy":{"slot":null,"token_kind":null,"min_items":0,"max_items":0,"snapshot_bound":false},"server_injected_paths":[],"reference_policy":{"mode":"none"},"semantic_preflight":["loft_profiles_exist","loft_profiles_closed","loft_profiles_single_region"],"candidate_verifiers":["single_connected_body"]},
     "extrude_add_two_sided": {"atomic_id":"extrude_add_two_sided","contract_version":"3.0","fragment_shape":{"sketch":"required","params":"required_object","selector_tokens":"forbidden"},"author_params_schema":{"type":"object","properties":{"distance_mm":{"type":"number","exclusiveMinimum":0},"reverse_distance_mm":{"type":"number","exclusiveMinimum":0},"reverse":{"type":"boolean"},"end_condition":{"type":"object","properties":{"type":{"type":"string","minLength":1,"maxLength":48},"solidworks_code":{"type":"integer"}},"required":["type","solidworks_code"],"additionalProperties":false},"reverse_end_condition":{"type":"object","properties":{"type":{"type":"string","minLength":1,"maxLength":48},"solidworks_code":{"type":"integer"}},"required":["type","solidworks_code"],"additionalProperties":false}},"required":["distance_mm","reverse_distance_mm"],"additionalProperties":false},"selector_policy":{"slot":null,"token_kind":null,"min_items":0,"max_items":0,"snapshot_bound":false},"server_injected_paths":[],"reference_policy":{"mode":"none"},"semantic_preflight":["sketch_workplane","profile_non_self_intersecting"],"candidate_verifiers":["single_connected_body"]},
     "extrude_cut_blind": {"atomic_id":"extrude_cut_blind","contract_version":"3.0","fragment_shape":{"sketch":"required","params":"required_object","selector_tokens":"forbidden"},"author_params_schema":{"type":"object","properties":{"distance_mm":{"type":"number","exclusiveMinimum":0},"reverse":{"type":"boolean"}},"required":["distance_mm"],"additionalProperties":false},"selector_policy":{"slot":null,"token_kind":null,"min_items":0,"max_items":0,"snapshot_bound":false},"server_injected_paths":[],"reference_policy":{"mode":"none"},"semantic_preflight":["requires_active_solid","sketch_workplane","profile_non_self_intersecting","cut_exit_distance"],"candidate_verifiers":["single_connected_body","volume_decreased"]},
     "extrude_cut_through": {"atomic_id":"extrude_cut_through","contract_version":"3.0","fragment_shape":{"sketch":"required","params":"required_object","selector_tokens":"forbidden"},"author_params_schema":{"type":"object","properties":{"reverse":{"type":"boolean"},"end_condition":{"type":"object","properties":{"type":{"type":"string","minLength":1,"maxLength":48},"solidworks_code":{"type":"integer"}},"required":["type","solidworks_code"],"additionalProperties":false}},"required":["end_condition"],"additionalProperties":false},"selector_policy":{"slot":null,"token_kind":null,"min_items":0,"max_items":0,"snapshot_bound":false},"server_injected_paths":[],"reference_policy":{"mode":"none"},"semantic_preflight":["requires_active_solid","sketch_workplane","profile_non_self_intersecting"],"candidate_verifiers":["single_connected_body","volume_decreased"]},
+    "extrude_cut_two_sided": {"atomic_id":"extrude_cut_two_sided","contract_version":"3.0","fragment_shape":{"sketch":"required","params":"required_object","selector_tokens":"forbidden"},"author_params_schema":{"type":"object","properties":{"distance_mm":{"type":"number","exclusiveMinimum":0},"reverse_distance_mm":{"type":"number","exclusiveMinimum":0},"reverse":{"type":"boolean"},"end_condition":{"type":"object","properties":{"type":{"type":"string","minLength":1,"maxLength":48},"solidworks_code":{"type":"integer"}},"required":["type","solidworks_code"],"additionalProperties":false},"reverse_end_condition":{"type":"object","properties":{"type":{"type":"string","minLength":1,"maxLength":48},"solidworks_code":{"type":"integer"}},"required":["type","solidworks_code"],"additionalProperties":false}},"required":["distance_mm","reverse_distance_mm"],"additionalProperties":false},"selector_policy":{"slot":null,"token_kind":null,"min_items":0,"max_items":0,"snapshot_bound":false},"server_injected_paths":[],"reference_policy":{"mode":"none"},"semantic_preflight":["requires_active_solid","sketch_workplane","profile_non_self_intersecting","cut_exit_distance"],"candidate_verifiers":["single_connected_body","volume_decreased"]},
     "revolve_add": {"atomic_id":"revolve_add","contract_version":"3.0","fragment_shape":{"sketch":"required","params":"required_object","selector_tokens":"forbidden"},"author_params_schema":{"type":"object","properties":{"angle_deg":{"type":"number","exclusiveMinimum":0,"maximum":360},"axis":{"type":"object","properties":{"origin_mm":{"type":"array","items":{"type":"number"},"minItems":3,"maxItems":3},"direction":{"type":"array","items":{"type":"number"},"minItems":3,"maxItems":3}},"required":["origin_mm","direction"],"additionalProperties":false},"reverse":{"type":"boolean"}},"required":["angle_deg","axis"],"additionalProperties":false},"selector_policy":{"slot":null,"token_kind":null,"min_items":0,"max_items":0,"snapshot_bound":false},"server_injected_paths":[],"reference_policy":{"mode":"none"},"semantic_preflight":["sketch_workplane","revolve_axis_on_sketch"],"candidate_verifiers":["single_connected_body"]},
     "revolve_cut": {"atomic_id":"revolve_cut","contract_version":"3.0","fragment_shape":{"sketch":"required","params":"required_object","selector_tokens":"forbidden"},"author_params_schema":{"type":"object","properties":{"angle_deg":{"type":"number","exclusiveMinimum":0,"maximum":360},"axis":{"type":"object","properties":{"origin_mm":{"type":"array","items":{"type":"number"},"minItems":3,"maxItems":3},"direction":{"type":"array","items":{"type":"number"},"minItems":3,"maxItems":3}},"required":["origin_mm","direction"],"additionalProperties":false},"reverse":{"type":"boolean"}},"required":["angle_deg","axis"],"additionalProperties":false},"selector_policy":{"slot":null,"token_kind":null,"min_items":0,"max_items":0,"snapshot_bound":false},"server_injected_paths":[],"reference_policy":{"mode":"none"},"semantic_preflight":["requires_active_solid","sketch_workplane","revolve_axis_on_sketch"],"candidate_verifiers":["single_connected_body","volume_decreased"]},
     "hole_blind": {"atomic_id":"hole_blind","contract_version":"3.0","fragment_shape":{"sketch":"forbidden","params":"required_object","selector_tokens":"required"},"author_params_schema":{"type":"object","properties":{"diameter_mm":{"type":"number","exclusiveMinimum":0},"depth_mm":{"type":"number","exclusiveMinimum":0},"positions":{"type":"array","minItems":1,"maxItems":64,"items":{"type":"object","properties":{"mm":{"type":"array","items":{"type":"number"},"minItems":3,"maxItems":3}},"required":["mm"],"additionalProperties":false}},"drill_angle_rad":{"type":"number","exclusiveMinimum":0,"maximum":3.141592653589793}},"required":["diameter_mm","depth_mm","positions"],"additionalProperties":false},"selector_policy":{"slot":"params.host_face","token_kind":"face","min_items":1,"max_items":1,"snapshot_bound":true},"server_injected_paths":["params.host_face"],"reference_policy":{"mode":"none"},"semantic_preflight":["host_face_exists","hole_positions_on_host_plane","cut_exit_distance"],"candidate_verifiers":["cylindrical_bore","through_cylindrical_bore"]},
@@ -71,7 +73,7 @@
       "constraints": ["vertices contains at least three [u, v] points"]
     },
     "analytic_contours": {
-      "summary": "Closed executable line, arc and circle contours. B-splines are unsupported in contours; imported construction B-splines are retained as non-executable audit geometry."
+      "summary": "Closed executable line, arc, circle and interpolation B-spline contours. Executable B-splines preserve ordered interpolation points and must be closed; imported construction B-splines remain non-executable audit geometry."
     }
   }
 }
diff --git a/backend/engine/cdsl_engine/runtime.py b/backend/engine/cdsl_engine/runtime.py
index d91d6a04..3118a5a6 100644
--- a/backend/engine/cdsl_engine/runtime.py
+++ b/backend/engine/cdsl_engine/runtime.py
@@ -20,8 +20,8 @@ from .sketch_solver import CORE_SHAPE_GENERATORS, resolve_required_sketches
 
 
 ALL_ATOMIC_IDS = frozenset({
-    "extrude_add_blind", "extrude_add_two_sided", "extrude_cut_blind",
-    "extrude_cut_through",
+    "extrude_add_blind", "extrude_add_two_sided", "extrude_cut_blind", "extrude_cut_two_sided",
+    "extrude_cut_through", "loft_add",
     "revolve_add", "revolve_cut", "hole_blind", "hole_countersink",
     "hole_counterbore", "sphere_add", "box_add", "cylinder_add",
     "reference_plane", "reference_axis",
@@ -82,6 +82,7 @@ class GeometryAdapter(Protocol):
     def body_solids(self, body: Any) -> list[Any]: ...
     def body_geometry(self, body: Any) -> dict[str, Any]: ...
     def faces_for_sketch(self, sketch: dict[str, Any]) -> list[Any]: ...
+    def loft(self, sketches: list[dict[str, Any]]) -> Any: ...
     def extrude(self, face: Any, direction: Vector3) -> Any: ...
     def extrude_trimmed(self, face: Any, target: Any, direction: Vector3) -> Any: ...
     def revolve(self, face: Any, angle_deg: float, axis: AxisSpec) -> Any: ...
@@ -236,7 +237,7 @@ def _targeted_extent_vector(
         except ValueError as error:
             message = str(error)
             code = "non_uniform_extent_target" if "non-uniform" in message else "extent_target_not_reached"
-            if condition == "up_to_surface":
+            if condition in {"up_to_surface", "through_next"}:
                 # #5 高级终止条件：profile 与目标面非均匀相交（部分采样点未
                 # 命中目标 → 悬空；或各点命中距离不一 → 斜目标面）时不再整体
                 # 拒绝，而是"裁剪"——只保留从 profile 到目标面之间的材料。
@@ -244,6 +245,7 @@ def _targeted_extent_vector(
                 # 目标的部分被切掉（CAD "拉伸到面"标准语义）。若全部采样点都
                 # 未命中（profile 与目标面无交叠），extrude_trimmed 内部仍抛
                 # "not reached"，保持显式拒绝。
+                # through_next 从当前主体中选取实际命中的下一张面；
                 # up_to_vertex/up_to_body/offset_from_surface 无 face 可构造
                 # 裁剪体层，仍保持显式拒绝。
                 return ExtentVector(vector_scale(direction, 1.0), trim_to=target)
@@ -271,7 +273,7 @@ def _side_extent_vectors(
 ) -> list[ExtentVector]:
     """Resolve one directional extent without borrowing the opposite side.
 
-    ``extrude_add_two_sided`` calls this once for each independently captured
+    ``extrude_add_two_sided`` and ``extrude_cut_two_sided`` call this once for each independently captured
     termination.  The regular one-sided executor also uses it for all simple
     termination modes, keeping the geometry adapter interface uniform.
     """
@@ -319,7 +321,7 @@ def _extent_vectors(
     end_condition = params.get("end_condition") or {"type": "blind"}
     condition = end_condition.get("type", "blind")
     distance = abs(float(params.get("distance_mm") or 0.0))
-    if node.atomic_id == "extrude_add_two_sided":
+    if node.atomic_id in {"extrude_add_two_sided", "extrude_cut_two_sided"}:
         reverse_condition = params.get("reverse_end_condition") or {"type": "blind"}
         reverse_distance = abs(float(params.get("reverse_distance_mm") or 0.0))
         if reverse_distance <= 0:
@@ -457,6 +459,21 @@ def _shape_from_primary(node: FeaturePlanNode, session: ExecutionSession, *, ske
     return session.result(node)
 
 
+def _execute_loft_add(node: FeaturePlanNode, session: ExecutionSession) -> FeatureResult:
+    # 放样截面不占用 feature.sketch_id；按有序 profile_sketch_ids 取已解析
+    # 草图，并由 adapter 统一校验单闭环、无内环等内核输入约束。
+    profile_ids = node.params.get("profile_sketch_ids") or []
+    profiles: list[dict[str, Any]] = []
+    for sketch_id in profile_ids:
+        sketch = session.sketches.get(str(sketch_id))
+        if sketch is None:
+            raise ValueError(f"loft profile sketch {sketch_id!r} is not resolved")
+        profiles.append(sketch)
+    solid = session.adapter.loft(profiles)
+    session.register_body(node.feature_id, session.adapter.fuse(session.body, solid), replay_node=node)
+    return session.result(node)
+
+
 def _execute_reference_plane(node: FeaturePlanNode, session: ExecutionSession) -> FeatureResult:
     # 基准面特征（reference_plane）执行入口：从参数解析平面并登记为拓扑上下文。
     
@@ -763,6 +780,11 @@ def _translated_sketch(sketch: dict[str, Any], offset: Vector3) -> dict[str, Any
                 for point_key in ("start_mm", "end_mm", "center_mm"):
                     if point_key in value:
                         value[point_key] = [float(value[point_key][index]) + components[index] for index in range(3)]
+                if "points_mm" in value:
+                    value["points_mm"] = [
+                        [float(point[index]) + components[index] for index in range(3)]
+                        for point in value["points_mm"]
+                    ]
                 for child in value.values():
                     translate(child)
             elif isinstance(value, list):
@@ -772,6 +794,30 @@ def _translated_sketch(sketch: dict[str, Any], offset: Vector3) -> dict[str, Any
     return output
 
 
+def _transformed_loft_profiles(
+    node: FeaturePlanNode,
+    params: dict[str, Any],
+    instance_id: str,
+    session: ExecutionSession,
+    transform: Callable[[dict[str, Any]], dict[str, Any]],
+) -> None:
+    """为 pattern replay 创建放样截面的变换副本。"""
+    if node.atomic_id != "loft_add":
+        return
+    profile_ids = params.get("profile_sketch_ids") or []
+    transformed_ids: list[str] = []
+    for index, sketch_id in enumerate(profile_ids):
+        source = session.sketches.get(str(sketch_id))
+        if source is None:
+            raise ValueError(f"loft profile sketch {sketch_id!r} has no replay definition")
+        transformed_id = f"{instance_id}.profile.{index}"
+        # 不复用原 profile：pattern 中的每个截面都必须与 source feature
+        # 使用相同的平移、镜像或旋转，才能保持放样的真实空间位置。
+        session.sketches[transformed_id] = transform(source)
+        transformed_ids.append(transformed_id)
+    params["profile_sketch_ids"] = transformed_ids
+
+
 def _owner_plane_frame(session: ExecutionSession, selector: dict[str, Any]) -> dict[str, Any] | None:
     """解析 selector 的 owner 特征（reference_plane）注册的显式平面 frame。
 
@@ -812,6 +858,10 @@ def _translated_node(node: FeaturePlanNode, instance_id: str, offset: Vector3, s
         # box_add/sphere_add 以世界坐标几何中心定位；平移重放必须随实例移动该中心，
         # 否则阵列副本会静默重合在原位置。
         params["center_mm"] = [float(center[index]) + components[index] for index in range(3)]
+    _transformed_loft_profiles(
+        node, params, instance_id, session,
+        lambda sketch: _translated_sketch(sketch, offset),
+    )
     mirror_plane = params.get("mirror_plane")
     if isinstance(mirror_plane, dict) and node.atomic_id == "pattern_mirror":
         # #6 pattern 引用重解析：镜像面是 reference_plane 引用，随实例平移
@@ -919,6 +969,12 @@ def _mirrored_sketch(sketch: dict[str, Any], plane: PlaneSpec) -> dict[str, Any]
                 point = value.get(point_key)
                 if isinstance(point, list) and len(point) == 2:
                     value[point_key] = [float(point[0]), -float(point[1])]
+            if isinstance(value.get("points"), list):
+                value["points"] = [
+                    [float(point[0]), -float(point[1])]
+                    for point in value["points"]
+                    if isinstance(point, list) and len(point) == 2
+                ]
             for child in value.values():
                 mirror_local_coordinates(child)
         elif isinstance(value, list):
@@ -935,6 +991,8 @@ def _mirrored_sketch(sketch: dict[str, Any], plane: PlaneSpec) -> dict[str, Any]
             for point_key in ("start_mm", "end_mm", "center_mm"):
                 if point_key in value:
                     value[point_key] = _reflect_point(value[point_key], plane)
+            if "points_mm" in value:
+                value["points_mm"] = [_reflect_point(point, plane) for point in value["points_mm"]]
             if value.get("normal"):
                 value["normal"] = _reflect_point(value["normal"], plane, vector=True)
             for child in value.values():
@@ -994,6 +1052,10 @@ def _mirrored_node(node: FeaturePlanNode, instance_id: str, plane: PlaneSpec, se
         # 世界轴对齐，跨坐标平面镜像后仍保持朝向（斜镜像面在 _execute_mirror_pattern
         # 中已被显式拒绝）。
         params["center_mm"] = _reflect_point(center, plane)
+    _transformed_loft_profiles(
+        node, params, instance_id, session,
+        lambda sketch: _mirrored_sketch(sketch, plane),
+    )
     mirror_plane = params.get("mirror_plane")
     if isinstance(mirror_plane, dict) and node.atomic_id == "pattern_mirror":
         # #6 pattern 引用重解析：镜像重放 mirror source 时，其镜像面引用
@@ -1102,7 +1164,7 @@ def _rotated_sketch(sketch: dict[str, Any], axis: AxisSpec, angle_rad: float) ->
     # 环形阵列实例的草图：工作平面 frame（原点为点、x/y/normal 为向量）绕轴旋转；
     # 2D 局部实体坐标不动（frame 旋转后由草图求解器映射到新世界位置）。与
     # _translated_sketch 对"世界坐标轮廓点"的处理对称，这里把 start/end/center
-    # 世界坐标点绕轴旋转。
+    # 世界坐标点和圆弧法向绕轴旋转。
     output = deepcopy(sketch)
     workplane = output.get("workplane") or {}
     if workplane.get("origin_mm"):
@@ -1117,6 +1179,10 @@ def _rotated_sketch(sketch: dict[str, Any], axis: AxisSpec, angle_rad: float) ->
             for point_key in ("start_mm", "end_mm", "center_mm"):
                 if point_key in value:
                     value[point_key] = _rotated_point(value[point_key], axis, angle_rad)
+            if "points_mm" in value:
+                value["points_mm"] = [_rotated_point(point, axis, angle_rad) for point in value["points_mm"]]
+            if "normal" in value:
+                value["normal"] = list(_rotated_vector(tuple(float(v) for v in value["normal"]), axis, angle_rad))
             for child in value.values():
                 rotate(child)
         elif isinstance(value, list):
@@ -1168,6 +1234,10 @@ def _rotated_node(node: FeaturePlanNode, instance_id: str, axis: AxisSpec, angle
     center = params.get("center_mm")
     if isinstance(center, list) and len(center) == 3:
         params["center_mm"] = _rotated_point(center, axis, angle_rad)
+    _transformed_loft_profiles(
+        node, params, instance_id, session,
+        lambda sketch: _rotated_sketch(sketch, axis, angle_rad),
+    )
     if node.atomic_id in {"pattern_mirror", "pattern_circular"}:
         # pattern 引用旋转重解析：镜像面 / 内层源随本实例一起旋转，否则嵌套
         # pattern 作为 circular source 时重放会退化成错误几何（见 _translated_node）。
@@ -1281,6 +1351,11 @@ def _primary_executor(node: FeaturePlanNode, session: ExecutionSession, sketch:
     return _shape_from_primary(node, session, sketch=sketch)
 
 
+def _loft_executor(node: FeaturePlanNode, session: ExecutionSession, sketch: dict[str, Any] | None) -> FeatureResult:
+    del sketch
+    return _execute_loft_add(node, session)
+
+
 def _reference_plane_executor(node: FeaturePlanNode, session: ExecutionSession, sketch: dict[str, Any] | None) -> FeatureResult:
     del sketch
     return _execute_reference_plane(node, session)
@@ -1347,7 +1422,9 @@ EXECUTORS: dict[str, ExecutorFunction] = {
     "extrude_add_blind": _primary_executor,
     "extrude_add_two_sided": _primary_executor,
     "extrude_cut_blind": _primary_executor,
+    "extrude_cut_two_sided": _primary_executor,
     "extrude_cut_through": _primary_executor,
+    "loft_add": _loft_executor,
     "revolve_add": _primary_executor,
     "revolve_cut": _primary_executor,
     "hole_blind": _hole_executor,
diff --git a/backend/engine/cdsl_engine/sketch_solver.py b/backend/engine/cdsl_engine/sketch_solver.py
index 8f1d3093..b9429afc 100644
--- a/backend/engine/cdsl_engine/sketch_solver.py
+++ b/backend/engine/cdsl_engine/sketch_solver.py
@@ -1,9 +1,9 @@
 """Core CDSL sketch resolver.
 
 The runtime accepts only direct geometric descriptions: circles, straight-edge
-polygons, and closed analytic line/arc/circle contours.  Semantic shapes and
-historical profile macros belong to the importer compatibility layer and must
-be lowered before this module is invoked.
+polygons, and closed analytic line/arc/circle/B-spline contours. Semantic
+shapes and historical profile macros belong to the importer compatibility
+layer and must be lowered before this module is invoked.
 """
 
 from __future__ import annotations
@@ -81,6 +81,11 @@ def _transform_contours(contours: list[_Ctx], workplane: _Ctx) -> list[_Ctx]:
         if edge["type"] == "arc":
             output["center_mm"] = _to_3d(workplane, edge["center_mm"][0], edge["center_mm"][1])
             output["normal"] = list(normal)
+        elif edge["type"] == "bspline":
+            output["points_mm"] = [
+                _to_3d(workplane, point[0], point[1])
+                for point in edge["points_mm"]
+            ]
         transformed.append(output)
     return transformed
 
@@ -118,6 +123,8 @@ def _reverse(edge: _Ctx) -> _Ctx:
     output["start_mm"], output["end_mm"] = output["end_mm"], output["start_mm"]
     if output.get("type") == "arc" and "clockwise" in output:
         output["clockwise"] = not bool(output["clockwise"])
+    if output.get("type") == "bspline":
+        output["points_mm"] = list(reversed(output["points_mm"]))
     return output
 
 
@@ -176,7 +183,16 @@ def _segment_edges(segment: _Ctx) -> list[_Ctx]:
     if kind == "circle":
         return _circle_edges(segment)
     if kind == "bspline":
-        raise ValueError("analytic_contours: bspline requires an explicit approximation capability")
+        points = segment.get("points") or []
+        if len(points) < 3:
+            raise ValueError("analytic_contours: bspline needs at least 3 interpolation points")
+        converted = [_point(point) for point in points]
+        return [{
+            "type": "bspline",
+            "start_mm": converted[0],
+            "end_mm": converted[-1],
+            "points_mm": converted,
+        }]
     raise ValueError(f"analytic_contours: unsupported segment type {kind!r}")
 
 
@@ -185,6 +201,9 @@ def _sample_loop(edges: list[_Ctx]) -> list[tuple[float, float]]:
     for edge in edges:
         start = edge["start_mm"]
         points.append((float(start[0]), float(start[1])))
+        if edge.get("type") == "bspline":
+            points.extend((float(point[0]), float(point[1])) for point in edge["points_mm"][1:-1])
+            continue
         if edge.get("type") != "arc":
             continue
         center, end = edge["center_mm"], edge["end_mm"]
diff --git a/backend/tests/test_author_guidance.py b/backend/tests/test_author_guidance.py
index 3ba6d541..54af4727 100644
--- a/backend/tests/test_author_guidance.py
+++ b/backend/tests/test_author_guidance.py
@@ -73,7 +73,7 @@ class AuthorGuidanceTests(unittest.TestCase):
             self.assertLessEqual(len(selection.content), 1_200)
             self.assertIn("世界坐标", selection.content)
             covered.update(section_id for section_id in selection.section_ids if section_id.startswith("op-"))
-        self.assertEqual(covered, {"op-extrude-add", "op-extrude-cut", "op-revolve", "op-hole", "op-reference", "op-pattern", "op-finish", "op-sphere"})
+        self.assertEqual(covered, {"op-extrude-add", "op-extrude-cut", "op-loft", "op-revolve", "op-hole", "op-reference", "op-pattern", "op-finish", "op-sphere", "op-primitives", "op-thread"})
 
     def test_phase_repair_and_budget_selection_are_stable(self) -> None:
         guidance = FileAuthorGuidance(GUIDANCE_ROOT, max_chars=3_600)
diff --git a/backend/tests/test_engine_loft_geometry.py b/backend/tests/test_engine_loft_geometry.py
new file mode 100644
index 00000000..b40b92e6
--- /dev/null
+++ b/backend/tests/test_engine_loft_geometry.py
@@ -0,0 +1,117 @@
+from __future__ import annotations
+
+import tempfile
+import unittest
+from pathlib import Path
+
+from engine.cdsl_engine.runtime import rebuild_cdsl
+
+
+def _spline_profile(sketch_id: str, z: float) -> dict:
+    return {
+        "id": sketch_id,
+        "workplane": {"origin_mm": [0, 0, z], "x_dir": [1, 0, 0], "normal": [0, 0, 1]},
+        "profile": {
+            "type": "analytic_contours",
+            "contours": [{
+                "role": "outer",
+                "closed": True,
+                "segments": [{
+                    "type": "bspline",
+                    "start": [0, 0],
+                    "end": [0, 0],
+                    "points": [[0, 0], [20, 0], [25, 10], [15, 18], [0, 10], [0, 0]],
+                }],
+            }],
+        },
+    }
+
+
+class LoftGeometryTests(unittest.TestCase):
+    def test_open_bspline_segment_can_close_with_other_contour_edges(self):
+        cdsl = {
+            "schema": "cad.cdsl.llm.v1",
+            "schema_version": "1.1.0",
+            "kind": "part",
+            "part_id": "open-bspline-contour",
+            "meta": {"unit": "mm"},
+            "geometry": {"sketches": [{
+                "id": "profile",
+                "workplane": {"origin_mm": [0, 0, 0], "x_dir": [1, 0, 0], "normal": [0, 0, 1]},
+                "profile": {"type": "analytic_contours", "contours": [{
+                    "role": "outer", "closed": True,
+                    "segments": [
+                        {"type": "line", "start": [0, 0], "end": [0, 10]},
+                        {
+                            "type": "bspline", "start": [0, 10], "end": [0, 0],
+                            "points": [[0, 10], [4, 10], [4, 0], [0, 0]],
+                        },
+                    ],
+                }]},
+            }]},
+            "features": [{
+                "id": "add", "atomic_id": "extrude_add_blind", "depends_on": [],
+                "sketch_id": "profile", "params": {"distance_mm": 5},
+            }],
+        }
+        with tempfile.TemporaryDirectory() as tmp:
+            rebuilt = rebuild_cdsl(cdsl, Path(tmp) / "open-bspline-contour.step")
+        self.assertGreater(rebuilt["volume_mm3"], 1.0)
+
+    def test_bspline_loft_and_mirror_replay_produce_step(self):
+        cdsl = {
+            "schema": "cad.cdsl.llm.v1",
+            "schema_version": "1.1.0",
+            "kind": "part",
+            "part_id": "bspline-loft-mirror",
+            "meta": {"unit": "mm"},
+            "geometry": {"sketches": [_spline_profile("lower", 0), _spline_profile("upper", 20)]},
+            "features": [
+                {
+                    "id": "mirror_plane",
+                    "atomic_id": "reference_plane",
+                    "depends_on": [],
+                    "params": {"plane": {"origin_mm": [35, 0, 0], "x_dir": [0, 1, 0], "normal": [1, 0, 0]}},
+                    "execution_status": "supported",
+                },
+                {
+                    "id": "loft",
+                    "atomic_id": "loft_add",
+                    "depends_on": [],
+                    "params": {"profile_sketch_ids": ["lower", "upper"]},
+                    "execution_status": "supported",
+                },
+                {
+                    "id": "mirror",
+                    "atomic_id": "pattern_mirror",
+                    "depends_on": ["mirror_plane", "loft"],
+                    "params": {
+                        "source_feature_ids": ["loft"],
+                        "mirror_plane": {
+                            "kind": "plane",
+                            "owner_feature_id": "mirror_plane",
+                            "stable_id": "mirror-plane",
+                            "source": "runtime_snapshot",
+                            "confidence": 1.0,
+                        },
+                    },
+                    "selectors": [{
+                        "kind": "plane",
+                        "owner_feature_id": "mirror_plane",
+                        "stable_id": "mirror-plane",
+                        "source": "runtime_snapshot",
+                        "confidence": 1.0,
+                    }],
+                    "execution_status": "supported",
+                },
+            ],
+        }
+        with tempfile.TemporaryDirectory() as tmp:
+            rebuilt = rebuild_cdsl(cdsl, Path(tmp) / "loft.step")
+            self.assertGreater(rebuilt["volume_mm3"], 1.0)
+            self.assertEqual(rebuilt["solid_count"], 2)
+            self.assertEqual([item["feature_id"] for item in rebuilt["feature_results"]], ["mirror_plane", "loft", "mirror.m.loft", "mirror"])
+
+
+if __name__ == "__main__":
+    unittest.main()
diff --git a/backend/tests/test_engine_pattern_transform_contract.py b/backend/tests/test_engine_pattern_transform_contract.py
index 2aba2e95..0c21b28f 100644
--- a/backend/tests/test_engine_pattern_transform_contract.py
+++ b/backend/tests/test_engine_pattern_transform_contract.py
@@ -316,6 +316,55 @@ class PatternTransformContractTests(unittest.TestCase):
 
         self.assertAlmostEqual(rebuilt["volume_mm3"], 1000 + 72 + 24, places=5)
 
+    def test_circular_pattern_rotates_analytic_arc_normals_with_the_sketch(self) -> None:
+        """倾斜圆草图的环形阵列必须保持每条圆弧处于旋转后的工作平面。
+
+        ``analytic_contours`` 在运行时会预先展开为世界坐标的圆弧边。环形阵列
+        不能只旋转边端点和圆心：Build123d 依据 edge.normal 计算三点圆弧中点，
+        法向遗留在源草图平面会让中点偏离 wire 平面，最终报
+        ``Cannot build face(s): wires not planar``。该 fixture 使用绕 Z 轴的
+        垂直圆草图，保证每个实例都实际变换该法向。
+        """
+        cdsl = {
+            "schema": "cad.cdsl.llm.v1", "schema_version": "1.1.0", "kind": "part",
+            "part_id": "circular-arc-normal", "meta": {"unit": "mm"},
+            "geometry": {"sketches": [
+                {
+                    "id": "base", "workplane": _workplane(origin=[0, 0, 0], normal=[0, 0, 1]),
+                    "profile": {"type": "circle", "center": [0, 0], "radius_mm": 10},
+                },
+                {
+                    "id": "boss", "workplane": _workplane(origin=[0, -10, 0], normal=[0, 1, 0]),
+                    "profile": {"type": "analytic_contours", "contours": [{
+                        "role": "outer", "closed": True,
+                        "segments": [{"type": "circle", "center": [0, -5], "radius_mm": 1}],
+                    }]},
+                },
+            ]},
+            "features": [
+                {
+                    "id": "base_add", "atomic_id": "extrude_add_blind", "depends_on": [],
+                    "sketch_id": "base", "params": {"distance_mm": 10},
+                },
+                {
+                    "id": "boss_add", "atomic_id": "extrude_add_blind", "depends_on": ["base_add"],
+                    "sketch_id": "boss", "params": {"distance_mm": 2},
+                },
+                {
+                    "id": "repeat", "atomic_id": "pattern_circular", "depends_on": ["boss_add"],
+                    "params": {
+                        "source_feature_ids": ["boss_add"],
+                        "axis": {"origin_mm": [0, 0, 0], "direction": [0, 0, 1]},
+                        "pattern_count": 4, "sweep_angle_deg": 360,
+                    },
+                },
+            ],
+        }
+        with tempfile.TemporaryDirectory() as directory:
+            rebuilt = rebuild_cdsl(cdsl, Path(directory) / "circular-arc-normal.step")
+        self.assertGreater(rebuilt["volume_mm3"], math.pi * 1000)
+        self.assertEqual(rebuilt["solid_count"], 1)
+
 
 if __name__ == "__main__":
     unittest.main()
diff --git a/backend/tests/test_engine_runtime_foundation.py b/backend/tests/test_engine_runtime_foundation.py
index 43565df2..d31ae60f 100644
--- a/backend/tests/test_engine_runtime_foundation.py
+++ b/backend/tests/test_engine_runtime_foundation.py
@@ -918,6 +918,25 @@ class EngineRuntimeFoundationTests(unittest.TestCase):
         analysis = analyze_cdsl(cdsl)
         self.assertIn("missing_parameter", [item.code for item in analysis.feature_results[0].blockers])
 
+    def test_two_sided_cut_uses_independent_forward_and_reverse_distances(self) -> None:
+        from cdsl_engine.runtime import rebuild_cdsl
+
+        cdsl = self._base_block()
+        cdsl["geometry"]["sketches"].append({
+            "id": "cut", "workplane": {**_workplane(), "origin_mm": [0, 0, 5]},
+            "profile": {"type": "circle", "center": [0, 0], "radius_mm": 1},
+        })
+        cdsl["features"].append({
+            "id": "cut_1", "atomic_id": "extrude_cut_two_sided", "depends_on": ["base_add"],
+            "params": {
+                "distance_mm": 3, "reverse_distance_mm": 5,
+                "end_condition": {"type": "blind"}, "reverse_end_condition": {"type": "blind"},
+            }, "sketch_id": "cut",
+        })
+        with tempfile.TemporaryDirectory() as directory:
+            result = rebuild_cdsl(cdsl, Path(directory) / "two-sided-cut.step")
+        self.assertAlmostEqual(result["volume_mm3"], 1000.0 - 8.0 * 3.141592653589793, places=5)
+
     def test_revolve_can_resolve_an_owner_qualified_reference_axis(self) -> None:
         from cdsl_engine.runtime import rebuild_cdsl
 
@@ -1038,6 +1057,22 @@ class EngineRuntimeFoundationTests(unittest.TestCase):
                 result = rebuild_cdsl(cdsl, root / f"{name}.step")
                 self.assertAlmostEqual(result["volume_mm3"], 1000 - expected_depth * 3.141592653589793, places=5)
 
+    def test_through_next_trims_a_partially_overlapping_profile_to_the_next_body_face(self) -> None:
+        from cdsl_engine.runtime import rebuild_cdsl
+
+        base = self._base_block()
+        base["geometry"]["sketches"].append({
+            "id": "partial", "workplane": {"origin_mm": [0, 0, 12], "x_dir": [1, 0, 0], "normal": [0, 0, -1]},
+            "profile": {"type": "polygon", "vertices": [[3, -3], [9, -3], [9, 3], [3, 3]]},
+        })
+        base["features"].append({
+            "id": "partial_add", "atomic_id": "extrude_add_blind", "depends_on": ["base_add"],
+            "sketch_id": "partial", "params": {"distance_mm": 0, "end_condition": {"type": "through_next"}},
+        })
+        with tempfile.TemporaryDirectory() as directory:
+            result = rebuild_cdsl(base, Path(directory) / "partial-through-next.step")
+        self.assertAlmostEqual(result["volume_mm3"], 1000 + 24, places=5)
+
     def test_up_to_body_extent_uses_a_uniquely_resolved_body_record(self) -> None:
         from cdsl_engine.runtime import rebuild_cdsl
 
diff --git a/cadfs_to_cdsl/ENGINE_CAPABILITY_GAPS_BASELINE.md b/cadfs_to_cdsl/ENGINE_CAPABILITY_GAPS_BASELINE.md
new file mode 100644
index 00000000..5b651567
--- /dev/null
+++ b/cadfs_to_cdsl/ENGINE_CAPABILITY_GAPS_BASELINE.md
@@ -0,0 +1,103 @@
+# CADFS 基线 Engine 能力缺口与补齐清单
+
+基于原始 `cadfs_to_cdsl/output` 全量报告。受影响样本数可重叠，不可相加。
+
+## P0：主体、草图与核心特征
+
+| 能力缺口 | 受影响样本 | 需要补足的能力 |
+| --- | ---: | --- |
+| B 样条草图 / `skFitSpline` | 未单独统计 | 控制点、闭合 wire、B-spline edge，以及供 extrude、loft、sweep 使用的 profile |
+| 复杂草图轮廓 | 未单独统计 | 直线、圆弧、圆、椭圆、样条、多 wire 和孔洞的稳定闭合与排序 |
+| `shell` | 696 | 移除面、壁厚、内/外方向、多实体和失败诊断 |
+| `sweep` | 326 | 截面、路径、导轨、实体/曲面模式、扭转和过渡策略 |
+| `loft` | 309 | 多 profile、闭合/开口 profile、导轨、实体/曲面模式和 profile 对齐 |
+| `booleanBodies` | 187 | union、subtract、intersect、目标/工具 body 和保留工具体策略 |
+| `circularPattern` | 232 | source feature 重放、旋转轴、数量、角度范围和嵌套 pattern |
+
+## P0：拉伸语义
+
+| 能力缺口 | 受影响样本 | 需要补足的能力 |
+| --- | ---: | --- |
+| `extrude_cut_through_all` | 303 | 按目标 body 实际交段执行穿透全部切除 |
+| `extrude_cut_two_sided` | 262 | 正反独立距离和终止条件的双向切除 |
+| `extrude_extent:up_to_surface` | 95 | 到面终止与非平面 profile 裁剪 |
+| `extrude_extent:up_to_next` | 49 | 到下一实体终止 |
+| `extrude_add_through_all` | 4 | 穿透全部加料拉伸 |
+| `extrude_extent:up_to_vertex` | 4 | 到顶点终止 |
+| `extrude_surface_or_mixed` | 4 | 曲面拉伸和 surface/solid 混合拓扑 |
+| `extrude_extent:up_to_body` | 2 | 到指定 body 终止 |
+
+## P1：selector 与基准面
+
+| 能力缺口 | 受影响样本 | 需要补足的能力 |
+| --- | ---: | --- |
+| `extrude_profile_topology:intersect` | 382 | 面/边交集 selector 与持久化 |
+| `extrude_profile_topology:cap_face` | 200 | 拉伸端盖面 selector |
+| `extrude_profile_topology:cap_edge` | 133 | 拉伸端盖边 selector |
+| `reference_plane:line_angle` | 123 | 线-角度基准面 |
+| `extrude_profile_topology:swept_face` | 99 | 侧壁面 selector |
+| `reference_plane:plane_point` | 47 | 平面-点基准面 |
+| `reference_plane:three_point` | 35 | 三点基准面 |
+| `reference_plane:mid_plane` | 25 | 两平面中面 |
+| `reference_plane:line_point` | 23 | 线-点基准面 |
+| `extrude_profile_topology:offset_face` | 18 | 偏移面 selector |
+| `extrude_profile_topology:swept_edge` | 16 | 侧壁边 selector |
+| `reference_plane:curve_point` | 13 | 曲线-点基准面 |
+| `extrude_profile_topology:mid_cap_edge` | 2 | 中性面端盖边 selector |
+
+## P1：已有特征的未覆盖语义
+
+| 特征 | 受影响样本 | 需要补足的能力 |
+| --- | ---: | --- |
+| `extrude` | 3,863 | 复杂 profile、拓扑引用和曲面/混合实体语义 |
+| `fillet` | 1,913 | 稳定边选择、切线传播、半径可行性 |
+| `revolve` | 742 | 轴选择、方向/角度、曲面模式和 profile 表达 |
+| `hole` | 623 | 孔型、螺纹、沉头/沉孔、终止条件和宿主面引用 |
+| `chamfer` | 588 | 距离-角度、双距离等参数及稳定边选择 |
+| `revolve_surface` | 367 | 曲面旋转及其与实体布尔的混合策略 |
+| `mirror` | 263 | source replay、镜像面引用和嵌套 pattern |
+| `cPlane` | 145 | 除 OFFSET 外的基准面构造和可重用 frame |
+
+## P2：未覆盖的 FeatureScript 操作
+
+| 能力缺口 | 需要补足的能力 |
+| --- | --- |
+| `draft` | 拔模面与中性面定义 |
+| `thicken` | 曲面加厚和方向控制 |
+| `split` | 面/实体分割与结果 body 管理 |
+| `moveFace` | 偏移、旋转、平移现有面 |
+| `deleteFace` | 删除面及修补策略 |
+| `replaceFace` | 面替换与拓扑更新 |
+| `derive` | 受控外部派生模型协议 |
+| `import` | 受控外部几何导入协议 |
+
+## 补齐清单
+
+### 第一阶段
+
+- [ ] 支持 B 样条草图和闭合 profile。
+- [ ] 新增 `loft_add`。
+- [ ] 新增 `shell`。
+- [ ] 新增 `sweep_add`。
+- [ ] 新增多 body boolean：union、subtract、intersect。
+- [ ] 为以上 FeatureScript 操作完成 lowering、schema、executor、adapter、selector 和端到端回归。
+
+### 第二阶段
+
+- [ ] 补齐 extrude 的 through-all、two-sided cut、up-to-surface、up-to-next、up-to-body、up-to-vertex。
+- [ ] 支持 `revolve_surface` 和 surface/solid 混合策略。
+- [ ] 补齐 `hole_wizard` 的 CADFS 孔型、螺纹和终止条件。
+- [ ] 补齐 `fillet`/`chamfer` 的参数变体、可行性预检查和稳定失败诊断。
+- [ ] 补齐 `circularPattern` 和 `mirror` 的 source replay、基准引用和嵌套 pattern。
+
+### 第三阶段
+
+- [ ] 补齐 CAP、SWEPT、OFFSET、INTERSECT、MID_CAP 等面/边 selector。
+- [ ] 补齐 line-angle、plane-point、three-point、mid-plane、line-point、curve-point 基准面。
+- [ ] 补齐 selector 的 owner、几何签名和歧义解析。
+
+### 第四阶段
+
+- [ ] 支持 `draft`、`thicken`、`split`。
+- [ ] 支持 `moveFace`、`deleteFace`、`replaceFace`。
+- [ ] 定义并实现 `derive`、`import` 的受控资产协议。
diff --git a/cadfs_to_cdsl/README.md b/cadfs_to_cdsl/README.md
index 7cdb1019..28f2a28f 100644
--- a/cadfs_to_cdsl/README.md
+++ b/cadfs_to_cdsl/README.md
@@ -14,3 +14,28 @@ PYTHONPATH=backend:. python -m cadfs_to_cdsl pipeline
 All stages are resumable. Use `--force` after changing converter behavior.
 The original CADFS directory is read-only; generated evidence is written under
 `cadfs_to_cdsl/output/samples/<sample_id>/`.
+
+## Representative regression pool
+
+Generate the checked-in representative manifest after a full corpus conversion:
+
+```bash
+PYTHONPATH=backend:. python -m cadfs_to_cdsl regression-select
+```
+
+The selector deterministically covers every observed FeatureScript modeling
+operation, sketch entity type, lowered CDSL atomic operation, unsupported
+operation, and unsupported engine-capability variant. It records which atomic
+operations have a successful engine baseline and which are diagnostic-only;
+the latter are never reported as passing builds. A normal engine change has a
+small, executable STEP regression command:
+
+```bash
+PYTHONPATH=backend:. python -m cadfs_to_cdsl regression --tier engine --stage rebuild
+```
+
+The command reruns by default; use `--resume` only to inspect cached results.
+Use `--tier conversion --stage convert` to verify feature lowering and
+diagnostics, or `--tier all --stage pipeline` for the complete representative
+conversion/rebuild/compare pass.  Unsupported CADFS features remain diagnostic
+coverage, not expected successful engine builds.
diff --git a/cadfs_to_cdsl/cli.py b/cadfs_to_cdsl/cli.py
index 9bcc1777..378449a1 100644
--- a/cadfs_to_cdsl/cli.py
+++ b/cadfs_to_cdsl/cli.py
@@ -4,6 +4,7 @@ import argparse, json
 from pathlib import Path
 from .describe import describe_samples
 from .pipeline import load_samples, run_stage, scan, select_samples
+from .regression import regression_sample_ids, summarize_regression, write_regression_manifest
 from .reports import generate_markdown_report, generate_reports, read_json
 
 DEFAULT_INPUT = Path("data/cadfs-sample/CADFS_test")
@@ -13,11 +14,21 @@ DEFAULT_OUTPUT = Path("cadfs_to_cdsl/output")
 def _parser() -> argparse.ArgumentParser:
     parser = argparse.ArgumentParser(description="Convert CADFS FeatureScript to CDSL and validate against STEP")
     commands = parser.add_subparsers(dest="command", required=True)
-    for name in ("scan", "convert", "rebuild", "compare", "report", "pipeline", "describe"):
+    for name in ("scan", "convert", "rebuild", "compare", "report", "pipeline", "describe", "regression-select", "regression"):
         command = commands.add_parser(name)
         command.add_argument("--input", type=Path, default=DEFAULT_INPUT)
         command.add_argument("--output", type=Path, default=DEFAULT_OUTPUT)
-        if name == "describe":
+        if name == "regression-select":
+            command.add_argument("--manifest", type=Path, default=Path("cadfs_to_cdsl/regression/manifest.json"))
+        elif name == "regression":
+            command.add_argument("--manifest", type=Path, default=Path("cadfs_to_cdsl/regression/manifest.json"))
+            command.add_argument("--tier", choices=("engine", "conversion", "all"), default="engine")
+            command.add_argument("--stage", choices=("convert", "rebuild", "compare", "pipeline"), default="rebuild")
+            command.add_argument("--workers", type=int, default=1)
+            command.add_argument("--compare-mode", choices=("rp", "strict"), default="rp")
+            command.add_argument("--timeout-seconds", type=float, default=30.0, help="per-model OCC timeout (default: 30)")
+            command.add_argument("--resume", action="store_true", help="reuse cached per-sample stage results instead of rerunning them")
+        elif name == "describe":
             command.add_argument("--shard", help="input shard directory to describe, for example 0005")
             command.add_argument("--sample-id", action="append")
             command.add_argument("--offset", type=int, default=0)
@@ -46,6 +57,16 @@ def main(argv: list[str] | None = None) -> int:
         args.output.mkdir(parents=True, exist_ok=True)
     if args.command == "scan":
         records = scan(args.input, args.output); result = {"sample_count": len(records), "output": str(args.output / "dataset_index.json")}
+    elif args.command == "regression-select":
+        manifest = write_regression_manifest(args.output, args.manifest)
+        result = {"manifest": str(args.manifest), "selected_sample_count": manifest["selected_sample_count"], "engine_sample_count": manifest["engine_sample_count"]}
+    elif args.command == "regression":
+        if not 1 <= args.workers <= 8: raise ValueError("--workers must be between 1 and 8")
+        if args.timeout_seconds <= 0: raise ValueError("--timeout-seconds must be positive")
+        sample_ids = regression_sample_ids(args.manifest, args.tier)
+        samples = select_samples(load_samples(args.input, args.output), sample_ids=sample_ids)
+        records = run_stage(args.stage, samples, args.output, force=not args.resume, compare_mode=args.compare_mode, timeout_seconds=args.timeout_seconds, workers=args.workers)
+        result = {"tier": args.tier, "stage": args.stage, "manifest": str(args.manifest), **summarize_regression(records)}
     elif args.command == "describe":
         records, result = describe_samples(
             args.input,
diff --git a/cadfs_to_cdsl/featurescript_parser.py b/cadfs_to_cdsl/featurescript_parser.py
index 3a360bd2..7dde2219 100644
--- a/cadfs_to_cdsl/featurescript_parser.py
+++ b/cadfs_to_cdsl/featurescript_parser.py
@@ -119,7 +119,7 @@ def parse_featurescript(source: str, sample_id: str = "unknown") -> ModelIR:
             if model.sketches:
                 args = _arg_map(call); eid = str(call.args[1]) if len(call.args) > 1 else f"E{len(model.sketches[-1].entities)}"
                 model.sketches[-1].entities.append(FeatureIR(eid, call.name, args, line_start=call.line, raw_source=call.name))
-        elif call.name in {"extrude", "revolve", "fillet", "chamfer", "hole", "linearPattern", "mirror", "cPlane", "referenceAxis", "shell", "loft", "sweep", "circularPattern", "booleanBodies"}:
+        elif call.name in {"extrude", "revolve", "fillet", "chamfer", "hole", "linearPattern", "mirror", "cPlane", "referenceAxis", "shell", "loft", "sweep", "circularPattern", "booleanBodies", "transform"}:
             fid = symbolic_string(call.args[1]) if len(call.args) > 1 else f"feature_{len(model.features)}"
             feature_ir = FeatureIR(fid, call.name, _arg_map(call), line_start=call.line, raw_source=call.name)
             model.features.append(feature_ir); model.steps.append(feature_ir)
diff --git a/cadfs_to_cdsl/lowering.py b/cadfs_to_cdsl/lowering.py
index 0d7fd0d8..ce37a358 100644
--- a/cadfs_to_cdsl/lowering.py
+++ b/cadfs_to_cdsl/lowering.py
@@ -8,7 +8,7 @@ from .ir import Call, FeatureIR, ModelIR, SketchIR
 from .query_parser import parse_query, walk_calls
 
 
-UNSUPPORTED = {"shell", "loft", "sweep", "draft", "thicken", "split", "booleanBodies", "circularPattern", "moveFace", "replaceFace", "deleteFace", "import", "derive"}
+UNSUPPORTED = {"shell", "sweep", "draft", "thicken", "split", "booleanBodies", "moveFace", "replaceFace", "deleteFace", "import", "derive"}
 PLANES = {
     "Top": {"origin_mm": [0., 0., 0.], "x_dir": [1., 0., 0.], "normal": [0., 0., 1.]},
     "Front": {"origin_mm": [0., 0., 0.], "x_dir": [1., 0., 0.], "normal": [0., -1., 0.]},
@@ -65,6 +65,43 @@ def _cross(a: list[float], b: list[float]) -> list[float]:
     return [a[1]*b[2]-a[2]*b[1], a[2]*b[0]-a[0]*b[2], a[0]*b[1]-a[1]*b[0]]
 
 
+def _dot(a: list[float], b: list[float]) -> float: return sum(left * right for left, right in zip(a, b))
+
+
+def _unit(value: list[float], message: str) -> list[float]:
+    length = math.sqrt(_dot(value, value))
+    if length <= 1e-9: raise ValueError(message)
+    return [component / length for component in value]
+
+
+def _sub(a: list[float], b: list[float]) -> list[float]: return [a[index] - b[index] for index in range(3)]
+
+
+def _rotate(value: list[float], axis: list[float], angle_rad: float) -> list[float]:
+    axis = _unit(axis, "rotation axis is degenerate")
+    cosine, sine = math.cos(angle_rad), math.sin(angle_rad)
+    cross = _cross(axis, value); projection = _dot(axis, value) * (1.0 - cosine)
+    return [value[index] * cosine + cross[index] * sine + axis[index] * projection for index in range(3)]
+
+
+def _translate_frame(frame: dict[str, Any], offset: list[float]) -> dict[str, Any]:
+    return {**frame, "origin_mm": [frame["origin_mm"][index] + offset[index] for index in range(3)]}
+
+
+def _rotate_point(point: list[float], axis: dict[str, list[float]], angle_rad: float) -> list[float]:
+    relative = _rotate(_sub(point, axis["origin_mm"]), axis["direction"], angle_rad)
+    return [axis["origin_mm"][index] + relative[index] for index in range(3)]
+
+
+def _rotate_frame(frame: dict[str, Any], axis: dict[str, list[float]], angle_rad: float) -> dict[str, Any]:
+    return {
+        **frame,
+        "origin_mm": _rotate_point(frame["origin_mm"], axis, angle_rad),
+        "x_dir": _rotate(frame["x_dir"], axis["direction"], angle_rad),
+        "normal": _rotate(frame["normal"], axis["direction"], angle_rad),
+    }
+
+
 def _y_dir(plane: dict[str, Any]) -> list[float]: return _cross(plane["normal"], plane["x_dir"])
 
 
@@ -81,6 +118,12 @@ def _oriented_plane(plane: dict[str, Any], normal_sign: float, distance: float =
     return {**shifted, "normal": [normal_sign * value for value in plane["normal"]]}
 
 
+def _frame(origin: list[float], x_dir: list[float], normal: list[float]) -> dict[str, list[float]]:
+    normal = _unit(normal, "reference plane normal is degenerate")
+    x_dir = _sub(x_dir, [normal[index] * _dot(x_dir, normal) for index in range(3)])
+    return {"origin_mm": origin, "x_dir": _unit(x_dir, "reference plane x direction is degenerate"), "normal": normal}
+
+
 def _plane_from_query(value: Any, feature_frames: dict[str, dict[str, Any]], sketch_by_source: dict[str, dict[str, Any]] | None = None) -> dict[str, Any]:
     for call in walk_calls(value):
         if call.name in {"makeId", "qCreatedBy"}:
@@ -107,6 +150,7 @@ def _end_condition(value: Any) -> dict[str, Any]:
     if name == "BLIND": return {"type": "blind", "solidworks_code": 0}
     if name == "SYMMETRIC": return {"type": "mid_plane", "solidworks_code": 8}
     if name == "THROUGH_ALL": return {"type": "through_all", "solidworks_code": 1}
+    if name == "UP_TO_NEXT": return {"type": "through_next", "solidworks_code": 4}
     raise UnsupportedCapability(f"extrude_extent:{name.lower()}", f"current CDSL atomic set has no exact extrusion operation for {name}")
 
 
@@ -137,12 +181,13 @@ def _contours(segments: list[dict[str, Any]]) -> tuple[list[dict[str, Any]], lis
             if _endpoint(item, True) == tail:
                 item["start"], item["end"] = item["end"], item["start"]
                 if item["type"] == "arc": item["clockwise"] = not item["clockwise"]
+                elif item["type"] == "bspline": item["points"] = list(reversed(item["points"]))
             contour.append(item); tail = _endpoint(item, True)
         if tail == first: contours.append({"role": "unknown", "closed": True, "segments": contour})
     return contours + circles, construction
 
 
-def _lower_sketch(sketch: SketchIR, plane: dict[str, Any]) -> tuple[dict[str, Any], dict[str, dict[str, Any]]]:
+def _lower_sketch(sketch: SketchIR, plane: dict[str, Any], allow_open: bool = False) -> tuple[dict[str, Any], dict[str, dict[str, Any]]]:
     segments: list[dict[str, Any]] = []; explicit_construction: list[dict[str, Any]] = []; entities: dict[str, dict[str, Any]] = {}; unsupported = []
     for entity in sketch.entities:
         p = entity.params
@@ -150,6 +195,10 @@ def _lower_sketch(sketch: SketchIR, plane: dict[str, Any]) -> tuple[dict[str, An
         if entity.operation == "skLineSegment": item = {"type": "line", "start": _point(p["start"]), "end": _point(p["end"])}
         elif entity.operation == "skCircle": item = {"type": "circle", "center": _point(p["center"]), "radius_mm": _number(p["radius"], True)}
         elif entity.operation == "skArc": item = _arc(_point(p["start"]), _point(p["mid"]), _point(p["end"]))
+        elif entity.operation == "skFitSpline":
+            points = [_point(point) for point in p.get("points") or []]
+            if len(points) < 3: raise ValueError("fit spline needs at least 3 points")
+            item = {"type": "bspline", "start": points[0], "end": points[-1], "points": points}
         else: unsupported.append(entity.operation); continue
         (explicit_construction if _bool(p.get("construction")) else segments).append(item); entities[entity.feature_id] = item
     if unsupported: raise ValueError("unsupported sketch entities: " + ",".join(sorted(set(unsupported))))
@@ -162,7 +211,9 @@ def _lower_sketch(sketch: SketchIR, plane: dict[str, Any]) -> tuple[dict[str, An
     else:
         contours, open_segments = _contours(segments)
         if open_segments:
-            raise ValueError(f"sketch has {len(open_segments)} open non-construction segment(s)")
+            if not allow_open: raise ValueError(f"sketch has {len(open_segments)} open non-construction segment(s)")
+            profile = {"type": "analytic_contours", "contours": [], "construction": explicit_construction + open_segments}
+            return {"id": f"sketch_{sketch.feature_id}", "name": sketch.feature_id, "workplane": plane, "profile": profile, "role": "reference"}, entities
         construction = list(explicit_construction)
         if not contours:
             profile = {"type": "analytic_contours", "contours": [], "construction": construction}
@@ -193,6 +244,89 @@ def _source_sketch(params: dict[str, Any]) -> str | None:
     return None
 
 
+def _pattern_source_features(value: Any, previous: list[str]) -> list[str]:
+    sources = []
+    for call in walk_calls(value):
+        if call.name != "makeQuery" or not call.args:
+            continue
+        owner = symbolic_string(call.args[0])
+        if "F" not in owner:
+            continue
+        source = "f_" + owner[owner.find("F"):].split(".", 1)[0]
+        if source in previous and source not in sources:
+            sources.append(source)
+    if not sources:
+        raise ValueError("pattern source features are unresolved")
+    return sources
+
+
+def _transform_source_features(value: Any, previous: list[str]) -> list[str]:
+    sources = []
+    for call in walk_calls(value):
+        if call.name not in {"makeQuery", "qCreatedBy"} or not call.args:
+            continue
+        owner = symbolic_string(call.args[0])
+        if "F" not in owner:
+            continue
+        source = "f_" + owner[owner.find("F"):].split(".", 1)[0]
+        if source in previous and source not in sources:
+            sources.append(source)
+    if not sources:
+        raise ValueError("transform source features are unresolved")
+    return sources
+
+
+def _circular_pattern_axis(
+    value: Any,
+    feature_frames: dict[str, dict[str, Any]],
+    sketch_by_source: dict[str, dict[str, Any]],
+    entity_by_sketch: dict[str, dict[str, dict[str, Any]]],
+) -> dict[str, list[float]]:
+    query = parse_query(value)
+    entity = (entity_by_sketch.get(query.source_sketch or "") or {}).get(query.source_entity or "")
+    if entity is None or query.source_sketch not in sketch_by_source:
+        raise ValueError("circular pattern axis is unresolved")
+    plane = sketch_by_source[query.source_sketch]["workplane"]
+    if entity["type"] == "line":
+        start = _global(plane, entity["start"]); end = _global(plane, entity["end"])
+        direction = [end[index] - start[index] for index in range(3)]
+        norm = math.sqrt(sum(component * component for component in direction))
+        if norm <= 1e-9:
+            raise ValueError("circular pattern axis line is degenerate")
+        return {"origin_mm": start, "direction": [component / norm for component in direction]}
+    if entity["type"] == "circle":
+        frame = feature_frames.get(query.owner_feature or "")
+        if frame and query.is_start is not None:
+            plane = frame["start" if query.is_start else "end"]
+        return {"origin_mm": _global(plane, entity["center"]), "direction": list(plane["normal"])}
+    raise ValueError("circular pattern axis must be a sketch line or circular edge")
+
+
+def _loft_profile_sketches(params: dict[str, Any]) -> list[str]:
+    # CADFS loft 的 profile 是草图 IMPRINT 面；几何仍来自原始闭合草图，
+    # 保留草图 source，不能把前序实体的选中面近似为新的放样轮廓。
+    profiles = params.get("sheetProfilesArray")
+    if not isinstance(profiles, list):
+        raise ValueError("loft sheetProfilesArray is unresolved")
+    sources: list[str] = []
+    for profile in profiles:
+        query_value = profile.get("sheetProfileEntities") if isinstance(profile, dict) else profile
+        query = parse_query(query_value)
+        if query.topology_type and query.topology_type != "IMPRINT":
+            raise UnsupportedCapability(
+                f"loft_profile_topology:{query.topology_type.lower()}",
+                f"current CDSL loft only supports sketch-imprint profiles, not {query.topology_type}",
+            )
+        if not query.source_sketch:
+            raise ValueError("loft profile sketch query is unresolved")
+        sources.append(query.source_sketch)
+    if len(sources) < 2:
+        raise ValueError("loft requires at least two profile sketches")
+    if len(set(sources)) != len(sources):
+        raise ValueError("loft profile sketches must be distinct")
+    return sources
+
+
 def _profile_query_kind(params: dict[str, Any]) -> str | None:
     for key in ("entities", "sheetProfilesArray"):
         if key in params:
@@ -215,18 +349,243 @@ def _default_plane(value: Any) -> dict[str, Any] | None:
     return None
 
 
+def _entity_from_query(
+    query: Any,
+    sketch_by_source: dict[str, dict[str, Any]],
+    entity_by_sketch: dict[str, dict[str, dict[str, Any]]],
+) -> tuple[dict[str, Any], dict[str, Any], str]:
+    info = parse_query(query); source = info.source_sketch or ""; token = info.source_entity or ""
+    available = entity_by_sketch.get(source) or {}
+    entity = available.get(token)
+    if entity is None:
+        entity_id = max((key for key in available if token.startswith(key + ".")), key=len, default="")
+        entity = available.get(entity_id)
+    sketch = sketch_by_source.get(source)
+    if entity is None or sketch is None:
+        raise ValueError("reference geometry source is unresolved")
+    return entity, sketch["workplane"], token
+
+
+def _entity_point(entity: dict[str, Any], plane: dict[str, Any], token: str) -> list[float]:
+    if entity["type"] == "point": return _global(plane, entity["point"])
+    if entity["type"] == "line":
+        local = entity["end"] if ".end" in token else entity["start"]
+        return _global(plane, local)
+    if entity["type"] == "bspline":
+        index = next((int(part) - 1 for part in token.split(".") if part.isdigit()), 0)
+        points = entity.get("points") or []
+        if not points: raise ValueError("B-spline reference point is unresolved")
+        return _global(plane, points[max(0, min(index, len(points) - 1))])
+    raise ValueError("reference entity does not define a point")
+
+
+def _entity_line(entity: dict[str, Any], plane: dict[str, Any]) -> tuple[list[float], list[float]]:
+    if entity["type"] != "line": raise ValueError("reference entity is not a line")
+    return _global(plane, entity["start"]), _global(plane, entity["end"])
+
+
+def _query_plane(
+    query: Any,
+    feature_frames: dict[str, dict[str, Any]],
+    sketch_by_source: dict[str, dict[str, Any]],
+    entity_by_sketch: dict[str, dict[str, dict[str, Any]]],
+) -> dict[str, Any]:
+    try:
+        return _plane_from_query(query, feature_frames, sketch_by_source)
+    except ValueError:
+        info = parse_query(query)
+        if info.topology_type != "SWEPT_FACE" or not info.owner_feature:
+            raise
+        entity, source_plane, _ = _entity_from_query(query, sketch_by_source, entity_by_sketch)
+        start, end = _entity_line(entity, source_plane); frame = feature_frames.get(info.owner_feature)
+        if frame is None: raise ValueError("swept face owner frame is unresolved")
+        direction = _unit(_sub(end, start), "swept face source line is degenerate")
+        normal = _cross(direction, frame["end"]["normal"])
+        return _frame(start, direction, normal)
+
+
+def _query_line(
+    query: Any,
+    feature_frames: dict[str, dict[str, Any]],
+    sketch_by_source: dict[str, dict[str, Any]],
+    entity_by_sketch: dict[str, dict[str, dict[str, Any]]],
+) -> tuple[list[float], list[float]]:
+    info = parse_query(query)
+    entity, plane, _ = _entity_from_query(query, sketch_by_source, entity_by_sketch)
+    if info.topology_type == "CAP_EDGE" and info.owner_feature in feature_frames:
+        frame = feature_frames[info.owner_feature]["start" if info.is_start else "end"]
+        plane = frame
+    return _entity_line(entity, plane)
+
+
+def _transform_axis(
+    query: Any,
+    feature_frames: dict[str, dict[str, Any]],
+    sketch_by_source: dict[str, dict[str, Any]],
+    entity_by_sketch: dict[str, dict[str, dict[str, Any]]],
+) -> dict[str, list[float]]:
+    start, end = _query_line(query, feature_frames, sketch_by_source, entity_by_sketch)
+    return {"origin_mm": start, "direction": _unit(_sub(end, start), "transform axis is degenerate")}
+
+
+def _bake_transform(
+    params: dict[str, Any],
+    previous: list[str],
+    feature_by_id: dict[str, dict[str, Any]],
+    feature_source_by_id: dict[str, str],
+    sketches_by_id: dict[str, dict[str, Any]],
+    feature_frames: dict[str, dict[str, Any]],
+    sketch_by_source: dict[str, dict[str, Any]],
+    entity_by_sketch: dict[str, dict[str, dict[str, Any]]],
+) -> None:
+    if _bool(params.get("makeCopy")):
+        raise UnsupportedCapability("transform", "current CDSL engine cannot exactly copy transformed CADFS source bodies")
+    sources = _transform_source_features(params.get("entities"), previous)
+    if len(sources) != 1:
+        raise UnsupportedCapability("transform", "current CDSL engine cannot exactly transform multiple selected CADFS source bodies")
+    source_id = sources[0]; source = feature_by_id.get(source_id)
+    if source is None or source.get("atomic_id") not in {"extrude_add_blind", "extrude_add_two_sided", "revolve_add"}:
+        raise UnsupportedCapability("transform", "current CDSL engine can only bake a direct additive extrusion or revolve transform")
+    sketch = sketches_by_id.get(str(source.get("sketch_id") or ""))
+    source_feature_id = feature_source_by_id.get(source_id)
+    if sketch is None or source_feature_id is None:
+        raise UnsupportedCapability("transform", "current CDSL engine cannot resolve the transformed source feature geometry")
+    transform_type = str(params.get("transformType") or "").split(".")[-1].upper()
+    if transform_type == "TRANSLATION_3D":
+        offset = [_number(params.get(key, 0.0), True) for key in ("dx", "dy", "dz")]
+        transform_frame = lambda frame: _translate_frame(frame, offset)
+        transform_axis = lambda axis: {**axis, "origin_mm": [axis["origin_mm"][index] + offset[index] for index in range(3)]}
+    elif transform_type == "ROTATION":
+        axis = _transform_axis(params.get("transformAxis"), feature_frames, sketch_by_source, entity_by_sketch)
+        angle_rad = math.radians(_number(params.get("angle"), True))
+        transform_frame = lambda frame: _rotate_frame(frame, axis, angle_rad)
+        transform_axis = lambda value: {
+            **value,
+            "origin_mm": _rotate_point(value["origin_mm"], axis, angle_rad),
+            "direction": _rotate(value["direction"], axis["direction"], angle_rad),
+        }
+    else:
+        raise UnsupportedCapability("transform", f"current CDSL engine cannot exactly bake {transform_type or 'unknown'} transform")
+    sketch["workplane"] = transform_frame(sketch["workplane"])
+    frame = feature_frames.get(source_feature_id)
+    if frame is not None:
+        feature_frames[source_feature_id] = {key: transform_frame(value) for key, value in frame.items()}
+    source_axis = source.get("params", {}).get("axis")
+    if isinstance(source_axis, dict) and source_axis.get("origin_mm") and source_axis.get("direction"):
+        source["params"]["axis"] = transform_axis(source_axis)
+
+
+def _query_point(
+    query: Any,
+    feature_frames: dict[str, dict[str, Any]],
+    sketch_by_source: dict[str, dict[str, Any]],
+    entity_by_sketch: dict[str, dict[str, dict[str, Any]]],
+) -> list[float]:
+    info = parse_query(query)
+    if info.topology_type == "CAP_VERTEX" and info.owner_feature in feature_frames:
+        references = _source_refs(query)
+        if len(references) >= 2:
+            plane = feature_frames[info.owner_feature]["start" if info.is_start else "end"]
+            lines = []
+            for source, token in references:
+                available = entity_by_sketch.get(source) or {}
+                entity = available.get(token)
+                if entity is None:
+                    entity_id = max((key for key in available if token.startswith(key + ".")), key=len, default="")
+                    entity = available.get(entity_id)
+                if entity and entity.get("type") == "line": lines.append(_entity_line(entity, plane))
+            if len(lines) >= 2:
+                pairs = [(math.dist(left, right), left) for left in lines[0] for right in lines[1]]
+                distance, point = min(pairs, key=lambda item: item[0])
+                if distance <= 1e-5: return point
+    entity, plane, token = _entity_from_query(query, sketch_by_source, entity_by_sketch)
+    if info.topology_type == "CAP_VERTEX" and info.owner_feature in feature_frames:
+        plane = feature_frames[info.owner_feature]["start" if info.is_start else "end"]
+    return _entity_point(entity, plane, token)
+
+
+def _cplane(
+    params: dict[str, Any],
+    feature_frames: dict[str, dict[str, Any]],
+    sketch_by_source: dict[str, dict[str, Any]],
+    entity_by_sketch: dict[str, dict[str, dict[str, Any]]],
+) -> dict[str, Any]:
+    plane_type = str(params.get("cplaneType") or "OFFSET").split(".")[-1].upper()
+    entities = _queries(params.get("entities"))
+    if plane_type == "OFFSET":
+        return _shift_plane(_query_plane(entities[0], feature_frames, sketch_by_source, entity_by_sketch), _number(params.get("offset", 0), True))
+    if plane_type == "LINE_ANGLE":
+        line_query = next((item for item in entities if parse_query(item).source_entity), None)
+        if line_query is None: raise ValueError("line-angle reference line is unresolved")
+        base_query = next((item for item in entities if item is not line_query), line_query)
+        try:
+            base = _query_plane(base_query, feature_frames, sketch_by_source, entity_by_sketch)
+        except ValueError:
+            _, base, _ = _entity_from_query(line_query, sketch_by_source, entity_by_sketch)
+        start, end = _query_line(line_query, feature_frames, sketch_by_source, entity_by_sketch)
+        axis = _sub(end, start); angle = _number(params.get("angle", 0.0))
+        if _bool(params.get("oppositeDirection")): angle = -angle
+        return _frame(start, _rotate(base["x_dir"], axis, math.radians(angle)), _rotate(base["normal"], axis, math.radians(angle)))
+    if plane_type == "PLANE_POINT":
+        base_query = next((item for item in entities if _default_plane(item) or "qCreatedBy" in parse_query(item).calls), None)
+        point_query = next((item for item in entities if item is not base_query), None)
+        if base_query is None or point_query is None: raise ValueError("plane-point references are unresolved")
+        base = _query_plane(base_query, feature_frames, sketch_by_source, entity_by_sketch)
+        return _frame(_query_point(point_query, feature_frames, sketch_by_source, entity_by_sketch), base["x_dir"], base["normal"])
+    if plane_type == "CURVE_POINT":
+        point_query = next((item for item in entities if parse_query(item).kind and "vertex" in parse_query(item).kind), None)
+        curve_query = next((item for item in entities if item is not point_query), None)
+        if point_query is None or curve_query is None: raise ValueError("curve-point references are unresolved")
+        point = _query_point(point_query, feature_frames, sketch_by_source, entity_by_sketch)
+        start, end = _query_line(curve_query, feature_frames, sketch_by_source, entity_by_sketch)
+        _, source_plane, _ = _entity_from_query(curve_query, sketch_by_source, entity_by_sketch)
+        return _frame(point, source_plane["normal"], _sub(end, start))
+    if plane_type == "THREE_POINT":
+        if len(entities) != 3: raise ValueError("three-point plane requires exactly three points")
+        first, second, third = [_query_point(item, feature_frames, sketch_by_source, entity_by_sketch) for item in entities]
+        normal = _cross(_sub(second, first), _sub(third, first))
+        if _bool(params.get("oppositeDirection")): normal = [-value for value in normal]
+        return _frame(first, _sub(second, first), normal)
+    if plane_type == "LINE_POINT":
+        line_query = next((item for item in entities if "edge" in (parse_query(item).kind or "")), None)
+        point_query = next((item for item in entities if item is not line_query), None)
+        if line_query is None or point_query is None: raise ValueError("line-point references are unresolved")
+        start, end = _query_line(line_query, feature_frames, sketch_by_source, entity_by_sketch)
+        point = _query_point(point_query, feature_frames, sketch_by_source, entity_by_sketch)
+        direction = _sub(end, start); normal = _cross(direction, _sub(point, start))
+        if _bool(params.get("oppositeDirection")): normal = [-value for value in normal]
+        return _frame(start, direction, normal)
+    if plane_type == "MID_PLANE":
+        if len(entities) != 2: raise ValueError("mid-plane requires exactly two reference planes")
+        first, second = [_query_plane(item, feature_frames, sketch_by_source, entity_by_sketch) for item in entities]
+        alignment = 1.0 if _dot(first["normal"], second["normal"]) >= 0 else -1.0
+        offset = _dot(_sub(second["origin_mm"], first["origin_mm"]), first["normal"]) * alignment
+        return _shift_plane(first, offset / 2.0)
+    raise UnsupportedCapability(f"reference_plane:{plane_type.lower()}", f"current converter has no exact {plane_type} reference plane")
+
+
 def lower_model(model: ModelIR, provenance: dict[str, Any]) -> LoweringResult:
     diagnostics: list[dict[str, Any]] = []; history = []
-    sketches: list[dict[str, Any]] = []; sketch_by_source: dict[str, dict[str, Any]] = {}; entity_by_sketch: dict[str, dict[str, dict[str, Any]]] = {}
+    sketches: list[dict[str, Any]] = []; sketches_by_id: dict[str, dict[str, Any]] = {}; sketch_by_source: dict[str, dict[str, Any]] = {}; entity_by_sketch: dict[str, dict[str, dict[str, Any]]] = {}
     feature_frames: dict[str, dict[str, Any]] = {}
     features: list[dict[str, Any]] = []; complete = True; previous: list[str] = []
+    feature_by_id: dict[str, dict[str, Any]] = {}; feature_source_by_id: dict[str, str] = {}
     for step in model.steps:
         if isinstance(step, SketchIR):
             history.append({"feature_id": step.feature_id, "operation": "newSketch", "parameters": {"sketchPlane": plain(step.workplane)}, "entities": [{"entity_id": e.feature_id, "operation": e.operation, "parameters": plain(e.params)} for e in step.entities]})
             try:
                 plane = _plane_from_query(step.workplane, feature_frames, sketch_by_source)
-                lowered, entities = _lower_sketch(step, plane); sketches.append(lowered); sketch_by_source[step.feature_id] = lowered; entity_by_sketch[step.feature_id] = entities
+                lowered, entities = _lower_sketch(step, plane); sketches.append(lowered); sketches_by_id[lowered["id"]] = lowered; sketch_by_source[step.feature_id] = lowered; entity_by_sketch[step.feature_id] = entities
             except Exception as exc:
+                # 开放草图不能作为实体 profile，但其几何仍可能是后续基准面、
+                # 阵列轴或旋转轴的精确引用。保留为 reference 草图，后续实体
+                # 特征仍由 _profile_executable 明确拒绝，不能静默把开放轮廓实体化。
+                try:
+                    plane = _plane_from_query(step.workplane, feature_frames, sketch_by_source)
+                    lowered, entities = _lower_sketch(step, plane, allow_open=True)
+                    sketches.append(lowered); sketches_by_id[lowered["id"]] = lowered; sketch_by_source[step.feature_id] = lowered; entity_by_sketch[step.feature_id] = entities
+                except Exception:
+                    pass
                 diagnostics.append({"code": "sketch_deferred", "feature_id": step.feature_id, "message": str(exc)}); complete = False
             continue
         item = step
@@ -235,12 +594,14 @@ def lower_model(model: ModelIR, provenance: dict[str, Any]) -> LoweringResult:
             diagnostics.append({"code": "unsupported_operation", "feature_id": item.feature_id, "operation": item.operation}); complete = False; continue
         try:
             fid = f"f_{item.feature_id}"; depends = list(previous[-1:]); p = item.params; feature: dict[str, Any]
-            if item.operation == "cPlane":
-                plane_type = str(p.get("cplaneType") or "OFFSET").split(".")[-1].upper()
-                if plane_type != "OFFSET":
-                    raise UnsupportedCapability(f"reference_plane:{plane_type.lower()}", f"current converter only supports exact OFFSET reference planes, not {plane_type}")
-                base = _plane_from_query(p.get("entities"), feature_frames, sketch_by_source); offset = _number(p.get("offset", 0), True); plane = _shift_plane(base, offset)
-                feature = {"id": fid, "name": item.feature_id, "atomic_id": "reference_plane", "depends_on": depends, "params": {"plane": plane, "offset_mm": offset}, "execution_status": "supported"}
+            if item.operation == "transform":
+                # 仅将单一、直接的原始实体变换烘焙回其输入几何。不能移动当前
+                # 聚合主体：CADFS transform 可能只选择 pattern copy 或多 body。
+                _bake_transform(p, previous, feature_by_id, feature_source_by_id, sketches_by_id, feature_frames, sketch_by_source, entity_by_sketch)
+                continue
+            elif item.operation == "cPlane":
+                plane = _cplane(p, feature_frames, sketch_by_source, entity_by_sketch)
+                feature = {"id": fid, "name": item.feature_id, "atomic_id": "reference_plane", "depends_on": depends, "params": {"plane": plane}, "execution_status": "supported"}
                 feature_frames[item.feature_id] = {"start": plane, "end": plane}
             elif item.operation == "extrude":
                 if p.get("surfaceOperationType") is not None:
@@ -255,19 +616,21 @@ def lower_model(model: ModelIR, provenance: dict[str, Any]) -> LoweringResult:
                 depth_value = p.get("depth"); depth = _number(depth_value, True) if depth_value is not None else 1.0
                 operation = str(p.get("operationType") or "NEW").upper(); reverse = _bool(p.get("oppositeDirection")); cutting = any(x in operation for x in ("REMOVE", "CUT"))
                 second = _bool(p.get("hasSecondDirection"))
-                if cutting and (second or end["type"] != "blind"):
-                    capability = "extrude_cut_two_sided" if second or end["type"] == "mid_plane" else f"extrude_cut_{end['type']}"
+                if cutting and not second and end["type"] not in {"blind", "mid_plane", "through_all", "through_next"}:
+                    capability = f"extrude_cut_{end['type']}"
                     raise UnsupportedCapability(capability, f"current CDSL atomic set has no exact {capability} operation")
-                if not cutting and not second and end["type"] not in {"blind", "mid_plane"}:
+                if not cutting and not second and end["type"] not in {"blind", "mid_plane", "through_all", "through_next"}:
                     capability = f"extrude_add_{end['type']}"
                     raise UnsupportedCapability(capability, f"current CDSL atomic set has no exact {capability} operation")
                 if second:
-                    atomic = "extrude_add_two_sided"; params = {"distance_mm": depth, "reverse": reverse, "end_condition": end}
+                    atomic = "extrude_cut_two_sided" if cutting else "extrude_add_two_sided"
+                    params = {"distance_mm": depth, "reverse": reverse, "end_condition": end}
                     reverse_depth = _number(p.get("secondDirectionDepth", depth), True)
                     params.update({"reverse_distance_mm": reverse_depth, "reverse_end_condition": _end_condition(p.get("secondDirectionBound"))})
-                elif end["type"] == "mid_plane" and not cutting:
+                elif end["type"] == "mid_plane":
                     blind = _end_condition("BLIND")
-                    atomic = "extrude_add_two_sided"; params = {"distance_mm": depth / 2, "reverse_distance_mm": depth / 2, "reverse": reverse, "end_condition": blind, "reverse_end_condition": dict(blind)}
+                    atomic = "extrude_cut_two_sided" if cutting else "extrude_add_two_sided"
+                    params = {"distance_mm": depth / 2, "reverse_distance_mm": depth / 2, "reverse": reverse, "end_condition": blind, "reverse_end_condition": dict(blind)}
                 else:
                     atomic = "extrude_cut_blind" if cutting else "extrude_add_blind"
                     params = {"distance_mm": depth, "reverse": reverse, "end_condition": end}
@@ -279,6 +642,22 @@ def lower_model(model: ModelIR, provenance: dict[str, Any]) -> LoweringResult:
                 elif end["type"] == "mid_plane":
                     direction = -1 if reverse else 1
                     feature_frames[item.feature_id] = {"start": _shift_plane(plane, -direction * depth / 2), "end": _shift_plane(plane, direction * depth / 2)}
+            elif item.operation == "loft":
+                sources = _loft_profile_sketches(p)
+                missing = [source for source in sources if source not in sketch_by_source]
+                if missing:
+                    raise ValueError("loft profile sketches are unresolved: " + ", ".join(missing))
+                non_closed = [source for source in sources if not _profile_executable(sketch_by_source[source])]
+                if non_closed:
+                    raise ValueError("loft profile sketches have no closed profile: " + ", ".join(non_closed))
+                feature = {
+                    "id": fid,
+                    "name": item.feature_id,
+                    "atomic_id": "loft_add",
+                    "depends_on": depends,
+                    "params": {"profile_sketch_ids": [sketch_by_source[source]["id"] for source in sources]},
+                    "execution_status": "supported",
+                }
             elif item.operation == "revolve":
                 if p.get("surfaceOperationType") is not None and p.get("operationType") is None:
                     raise UnsupportedCapability("revolve_surface", "current CDSL engine has no exact surface-revolve operation")
@@ -365,6 +744,25 @@ def lower_model(model: ModelIR, provenance: dict[str, Any]) -> LoweringResult:
                     hole_params["counterbore"] = {"diameter_mm": _number(p.get("counterboreDiameter") or p.get("cBoreDiameter") or p.get("majorDiameter"), True), "depth_mm": _number(p.get("counterboreDepth") or p.get("cBoreDepth"), True)}
                 if _bool(p.get("isTappedThrough")) or p.get("tapSize") is not None: hole_params["thread"] = {"source": "CADFS", "decorative": True}
                 feature = {"id": fid, "name": item.feature_id, "atomic_id": "hole_wizard", "depends_on": depends, "params": hole_params, "execution_status": "supported"}
+            elif item.operation == "circularPattern":
+                sources = _pattern_source_features(p.get("entities"), previous)
+                axis = _circular_pattern_axis(p.get("axis"), feature_frames, sketch_by_source, entity_by_sketch)
+                count = int(_number(p.get("instanceCount")))
+                if count < 1:
+                    raise ValueError("circular pattern instanceCount must be positive")
+                feature = {
+                    "id": fid,
+                    "name": item.feature_id,
+                    "atomic_id": "pattern_circular",
+                    "depends_on": list(dict.fromkeys(sources + depends)),
+                    "params": {
+                        "source_feature_ids": sources,
+                        "axis": axis,
+                        "pattern_count": count,
+                        "sweep_angle_deg": _number(p.get("angle", 360.0)),
+                    },
+                    "execution_status": "supported",
+                }
             elif item.operation == "mirror":
                 owners = []
                 for call in walk_calls(p.get("entities")):
@@ -387,7 +785,7 @@ def lower_model(model: ModelIR, provenance: dict[str, Any]) -> LoweringResult:
                 feature = {"id": fid, "name": item.feature_id, "atomic_id": "pattern_mirror", "depends_on": list(dict.fromkeys(owners + [plane_owner])), "params": {"source_feature_ids": owners, "mirror_plane": mirror_plane}, "selectors": [mirror_plane], "execution_status": "supported"}
             else:
                 raise ValueError(f"operation mapping not implemented: {item.operation}")
-            features.append(feature); previous.append(fid)
+            features.append(feature); feature_by_id[fid] = feature; feature_source_by_id[fid] = item.feature_id; previous.append(fid)
         except UnsupportedCapability as exc:
             diagnostics.append({"code": "unsupported_engine_capability", "capability": exc.capability, "feature_id": item.feature_id, "operation": item.operation, "message": str(exc)}); complete = False
         except Exception as exc:
diff --git a/cadfs_to_cdsl/pipeline.py b/cadfs_to_cdsl/pipeline.py
index 5e7655f6..0cee6328 100644
--- a/cadfs_to_cdsl/pipeline.py
+++ b/cadfs_to_cdsl/pipeline.py
@@ -103,7 +103,12 @@ def _isolated(target: Any, args: tuple[str, ...], result_path: Path, timeout_sec
 def rebuild_one(sample: Sample, output: Path, *, force: bool = False, timeout_seconds: float = 30.0) -> dict[str, Any]:
     directory = _sample_dir(output, sample.sample_id); status_path = directory / "status.json"
     status = read_json(status_path) if status_path.exists() else convert_one(sample, output, force=force)
-    if status.get("conversion_status") != "converted_complete": return status
+    # A partial conversion may still retain a self-contained, semantically
+    # executable CDSL prefix.  That prefix is valuable engine evidence and
+    # must be rebuilt instead of being hidden behind the conversion label.
+    # ``rebuild_candidate`` keeps the two outcomes distinct by reporting a
+    # runtime-ineligible candidate when no executable body can be produced.
+    if not (directory / "candidate.cdsl.json").exists(): return status
     rebuild_path = directory / "rebuild.json"; step_path = directory / "rebuild.step"
     if not force and rebuild_path.exists() and status.get("rebuild_status"):
         if status.get("rebuild_status") != "rebuilt" or step_path.exists(): return status
diff --git a/cadfs_to_cdsl/regression.py b/cadfs_to_cdsl/regression.py
new file mode 100644
index 00000000..8ca6e393
--- /dev/null
+++ b/cadfs_to_cdsl/regression.py
@@ -0,0 +1,216 @@
+"""Deterministic, feature-covering CADFS regression pools.
+
+The converted CADFS corpus is deliberately kept outside version control.  This
+module turns the artifacts already produced in ``output/samples`` into a small,
+versionable manifest that records why every selected source sample is needed.
+"""
+
+from __future__ import annotations
+
+from collections import Counter
+from pathlib import Path
+from typing import Any
+
+from .reports import read_json, write_json
+
+
+REGRESSION_SCHEMA = "cadfs_to_cdsl.regression.v1"
+
+
+def _tag(kind: str, value: str) -> str:
+    return f"{kind}:{value}"
+
+
+def _split_tag(tag: str) -> tuple[str, str]:
+    kind, separator, value = tag.partition(":")
+    if not separator:
+        raise ValueError(f"Malformed regression coverage tag: {tag!r}")
+    return kind, value
+
+
+def _sample_features(sample_dir: Path) -> dict[str, Any]:
+    """Read coverage signals from a converted sample without reparsing CADFS."""
+    history = read_json(sample_dir / "history.json") if (sample_dir / "history.json").exists() else []
+    candidate = read_json(sample_dir / "candidate.cdsl.json") if (sample_dir / "candidate.cdsl.json").exists() else {}
+    diagnostics = read_json(sample_dir / "diagnostics.json") if (sample_dir / "diagnostics.json").exists() else []
+    status = read_json(sample_dir / "status.json") if (sample_dir / "status.json").exists() else {}
+
+    source_operations: set[str] = set()
+    sketch_entities: set[str] = set()
+    for item in history:
+        if not isinstance(item, dict):
+            continue
+        operation = item.get("operation")
+        if isinstance(operation, str):
+            source_operations.add(operation)
+        for entity in item.get("entities") or ():
+            if isinstance(entity, dict) and isinstance(entity.get("operation"), str):
+                sketch_entities.add(str(entity["operation"]))
+
+    atomic_ids = {
+        str(feature["atomic_id"])
+        for feature in candidate.get("features") or ()
+        if isinstance(feature, dict) and isinstance(feature.get("atomic_id"), str)
+    }
+    unsupported_capabilities = {
+        str(item["capability"])
+        for item in diagnostics
+        if isinstance(item, dict)
+        and item.get("code") == "unsupported_engine_capability"
+        and isinstance(item.get("capability"), str)
+    }
+    unsupported_operations = {
+        str(item["operation"])
+        for item in diagnostics
+        if isinstance(item, dict)
+        and item.get("code") == "unsupported_operation"
+        and isinstance(item.get("operation"), str)
+    }
+    return {
+        "sample_id": sample_dir.name,
+        "source_operations": sorted(source_operations),
+        "sketch_entities": sorted(sketch_entities),
+        "engine_atomic_ids": sorted(atomic_ids),
+        "unsupported_capabilities": sorted(unsupported_capabilities),
+        "unsupported_operations": sorted(unsupported_operations),
+        "has_candidate": bool(candidate),
+        "baseline": {
+            key: status[key]
+            for key in ("conversion_status", "rebuild_status", "comparison_decision", "status")
+            if key in status
+        },
+    }
+
+
+def _tags(record: dict[str, Any]) -> set[str]:
+    return {
+        *(_tag("source_operation", item) for item in record["source_operations"]),
+        *(_tag("sketch_entity", item) for item in record["sketch_entities"]),
+        *(_tag("engine_atomic", item) for item in record["engine_atomic_ids"]),
+        *(_tag("unsupported_capability", item) for item in record["unsupported_capabilities"]),
+        *(_tag("unsupported_operation", item) for item in record["unsupported_operations"]),
+    }
+
+
+def _greedy_cover(records: list[dict[str, Any]], wanted: set[str], selected: list[dict[str, Any]]) -> dict[str, list[str]]:
+    """Cover ``wanted`` with stable maximum-coverage selection.
+
+    The sample id breaks ties, so a corpus refresh is reviewable and never
+    changes pool membership due to directory iteration order.
+    """
+    coverage: dict[str, list[str]] = {}
+    selected_ids = {record["sample_id"] for record in selected}
+    remaining = set(wanted)
+    while remaining:
+        choices = [record for record in records if record["sample_id"] not in selected_ids]
+        if not choices:
+            break
+        choice = min(
+            choices,
+            key=lambda record: (-len(_tags(record) & remaining), record["sample_id"]),
+        )
+        gained = _tags(choice) & remaining
+        if not gained:
+            break
+        selected.append(choice)
+        selected_ids.add(choice["sample_id"])
+        for tag in sorted(gained):
+            coverage.setdefault(tag, []).append(choice["sample_id"])
+        remaining -= gained
+    return coverage
+
+
+def build_regression_manifest(output: Path) -> dict[str, Any]:
+    """Build a compact pool covering every observed CADFS modeling signal."""
+    records = [_sample_features(directory) for directory in sorted((output / "samples").glob("*")) if directory.is_dir()]
+    if not records:
+        raise FileNotFoundError(f"No converted CADFS samples found under {output / 'samples'}")
+
+    all_tags = set().union(*(_tags(record) for record in records))
+    selected: list[dict[str, Any]] = []
+
+    # Give the engine pool a current successful baseline per atomic operation
+    # whenever the corpus has one.  Unsupported/failed atoms remain covered by
+    # the full conversion pool and are never represented as passing builds.
+    engine_records = [
+        record for record in records
+        if record["has_candidate"] and record["baseline"].get("rebuild_status") == "rebuilt"
+    ]
+    engine_tags = {_tag("engine_atomic", atom) for record in engine_records for atom in record["engine_atomic_ids"]}
+    _greedy_cover(engine_records, engine_tags, selected)
+    # Samples chosen for the executable baseline can also cover source and
+    # converter signals. Count those signals before the general pass so the
+    # final fixture remains genuinely representative rather than redundant.
+    coverage = {
+        tag: sorted(record["sample_id"] for record in selected if tag in _tags(record))
+        for tag in sorted(set().union(*(_tags(record) for record in selected)))
+    }
+    all_coverage = _greedy_cover(records, all_tags - set(coverage), selected)
+    for tag, sample_ids in all_coverage.items():
+        coverage[tag] = sorted(set(coverage.get(tag, []) + sample_ids))
+
+    selected_ids = {record["sample_id"] for record in selected}
+    missing = sorted(all_tags - set(coverage))
+    if missing:
+        raise RuntimeError("Unable to cover CADFS regression features: " + ", ".join(missing))
+
+    entries = []
+    for record in sorted(selected, key=lambda item: item["sample_id"]):
+        tags = _tags(record)
+        tiers = ["conversion"]
+        if record["sample_id"] in {item["sample_id"] for item in engine_records}:
+            tiers.append("engine")
+        entries.append({
+            **record,
+            "tiers": tiers,
+            "selection_reasons": sorted(tag for tag, sample_ids in coverage.items() if record["sample_id"] in sample_ids),
+        })
+
+    inventory: dict[str, dict[str, int]] = {}
+    for kind, _ in map(_split_tag, sorted(all_tags)):
+        inventory.setdefault(kind, {})
+    for tag in all_tags:
+        kind, value = _split_tag(tag)
+        inventory[kind][value] = sum(tag in _tags(record) for record in records)
+
+    return {
+        "schema": REGRESSION_SCHEMA,
+        "description": "Feature-covering representative CADFS regression pool. Engine samples have a prior successful rebuild; conversion samples retain unsupported-feature diagnostics.",
+        "source_output": str(output),
+        "source_sample_count": len(records),
+        "selected_sample_count": len(entries),
+        "engine_sample_count": sum("engine" in entry["tiers"] for entry in entries),
+        "conversion_sample_count": len(entries),
+        "engine_baseline_atomic_ids": sorted(tag.removeprefix("engine_atomic:") for tag in engine_tags),
+        "engine_diagnostic_only_atomic_ids": sorted(
+            tag.removeprefix("engine_atomic:") for tag in all_tags - engine_tags if tag.startswith("engine_atomic:")
+        ),
+        "feature_inventory": {kind: dict(sorted(values.items())) for kind, values in sorted(inventory.items())},
+        "coverage": coverage,
+        "entries": entries,
+        "selected_ids": sorted(selected_ids),
+    }
+
+
+def write_regression_manifest(output: Path, manifest_path: Path) -> dict[str, Any]:
+    manifest = build_regression_manifest(output)
+    write_json(manifest_path, manifest)
+    return manifest
+
+
+def regression_sample_ids(manifest_path: Path, tier: str) -> list[str]:
+    manifest = read_json(manifest_path)
+    if manifest.get("schema") != REGRESSION_SCHEMA:
+        raise ValueError(f"Unsupported regression manifest schema: {manifest.get('schema')!r}")
+    if tier not in {"engine", "conversion", "all"}:
+        raise ValueError(f"Unknown regression tier: {tier!r}")
+    entries = manifest.get("entries") or []
+    selected = [item["sample_id"] for item in entries if tier == "all" or tier in (item.get("tiers") or ())]
+    if not selected:
+        raise ValueError(f"Regression manifest has no samples for tier {tier!r}")
+    return sorted(selected)
+
+
+def summarize_regression(records: list[dict[str, Any]]) -> dict[str, Any]:
+    statuses = Counter(str(record.get("status") or "unknown") for record in records)
+    return {"sample_count": len(records), "statuses": dict(sorted(statuses.items()))}
diff --git a/cadfs_to_cdsl/regression/manifest.json b/cadfs_to_cdsl/regression/manifest.json
new file mode 100644
index 00000000..f866186c
--- /dev/null
+++ b/cadfs_to_cdsl/regression/manifest.json
@@ -0,0 +1,942 @@
+{
+  "conversion_sample_count": 17,
+  "coverage": {
+    "engine_atomic:chamfer": [
+      "00002243",
+      "00111611"
+    ],
+    "engine_atomic:extrude_add_blind": [
+      "00111611"
+    ],
+    "engine_atomic:extrude_add_two_sided": [
+      "00002243",
+      "00111611"
+    ],
+    "engine_atomic:extrude_cut_blind": [
+      "00002243",
+      "00129362"
+    ],
+    "engine_atomic:fillet": [
+      "00111611"
+    ],
+    "engine_atomic:hole_wizard": [
+      "00002243"
+    ],
+    "engine_atomic:pattern_mirror": [
+      "00925274"
+    ],
+    "engine_atomic:reference_plane": [
+      "00129362"
+    ],
+    "engine_atomic:revolve_add": [
+      "00111611",
+      "00129362"
+    ],
+    "engine_atomic:revolve_cut": [
+      "00129362"
+    ],
+    "sketch_entity:skArc": [
+      "00111611",
+      "00129362"
+    ],
+    "sketch_entity:skCircle": [
+      "00002243",
+      "00111611",
+      "00129362"
+    ],
+    "sketch_entity:skEllipse": [
+      "00287955"
+    ],
+    "sketch_entity:skFitSpline": [
+      "00542223"
+    ],
+    "sketch_entity:skLineSegment": [
+      "00002243",
+      "00111611",
+      "00129362"
+    ],
+    "sketch_entity:skPoint": [
+      "00002243",
+      "00129362"
+    ],
+    "source_operation:booleanBodies": [
+      "00835610"
+    ],
+    "source_operation:cPlane": [
+      "00129362"
+    ],
+    "source_operation:chamfer": [
+      "00002243",
+      "00111611"
+    ],
+    "source_operation:circularPattern": [
+      "00542223"
+    ],
+    "source_operation:extrude": [
+      "00002243",
+      "00111611",
+      "00129362"
+    ],
+    "source_operation:fillet": [
+      "00111611"
+    ],
+    "source_operation:hole": [
+      "00002243"
+    ],
+    "source_operation:loft": [
+      "00287955"
+    ],
+    "source_operation:mirror": [
+      "00925274"
+    ],
+    "source_operation:newSketch": [
+      "00002243",
+      "00111611",
+      "00129362"
+    ],
+    "source_operation:revolve": [
+      "00111611",
+      "00129362"
+    ],
+    "source_operation:shell": [
+      "00542223"
+    ],
+    "source_operation:sweep": [
+      "00542223"
+    ],
+    "unsupported_capability:extrude_add_through_all": [
+      "00159804"
+    ],
+    "unsupported_capability:extrude_cut_through_all": [
+      "00542223"
+    ],
+    "unsupported_capability:extrude_cut_two_sided": [
+      "00212904"
+    ],
+    "unsupported_capability:extrude_extent:up_to_body": [
+      "00694309"
+    ],
+    "unsupported_capability:extrude_extent:up_to_next": [
+      "00192744"
+    ],
+    "unsupported_capability:extrude_extent:up_to_surface": [
+      "00925274"
+    ],
+    "unsupported_capability:extrude_extent:up_to_vertex": [
+      "00423838"
+    ],
+    "unsupported_capability:extrude_profile_topology:cap_edge": [
+      "00287955"
+    ],
+    "unsupported_capability:extrude_profile_topology:cap_face": [
+      "00835610"
+    ],
+    "unsupported_capability:extrude_profile_topology:intersect": [
+      "00835610"
+    ],
+    "unsupported_capability:extrude_profile_topology:mid_cap_edge": [
+      "00612529"
+    ],
+    "unsupported_capability:extrude_profile_topology:offset_face": [
+      "00789939"
+    ],
+    "unsupported_capability:extrude_profile_topology:swept_edge": [
+      "00054089"
+    ],
+    "unsupported_capability:extrude_profile_topology:swept_face": [
+      "00789939"
+    ],
+    "unsupported_capability:extrude_surface_or_mixed": [
+      "00710855"
+    ],
+    "unsupported_capability:reference_plane:curve_point": [
+      "00192744"
+    ],
+    "unsupported_capability:reference_plane:line_angle": [
+      "00925274"
+    ],
+    "unsupported_capability:reference_plane:line_point": [
+      "00035682"
+    ],
+    "unsupported_capability:reference_plane:mid_plane": [
+      "00287955"
+    ],
+    "unsupported_capability:reference_plane:plane_point": [
+      "00542223"
+    ],
+    "unsupported_capability:reference_plane:three_point": [
+      "00212904"
+    ],
+    "unsupported_capability:revolve_surface": [
+      "00835610"
+    ],
+    "unsupported_operation:booleanBodies": [
+      "00835610"
+    ],
+    "unsupported_operation:circularPattern": [
+      "00542223"
+    ],
+    "unsupported_operation:loft": [
+      "00287955"
+    ],
+    "unsupported_operation:shell": [
+      "00542223"
+    ],
+    "unsupported_operation:sweep": [
+      "00542223"
+    ]
+  },
+  "description": "Feature-covering representative CADFS regression pool. Engine samples have a prior successful rebuild; conversion samples retain unsupported-feature diagnostics.",
+  "engine_baseline_atomic_ids": [
+    "chamfer",
+    "extrude_add_blind",
+    "extrude_add_two_sided",
+    "extrude_cut_blind",
+    "fillet",
+    "hole_wizard",
+    "reference_plane",
+    "revolve_add",
+    "revolve_cut"
+  ],
+  "engine_diagnostic_only_atomic_ids": [
+    "pattern_mirror"
+  ],
+  "engine_sample_count": 3,
+  "entries": [
+    {
+      "baseline": {
+        "comparison_decision": "rejected",
+        "conversion_status": "converted_complete",
+        "rebuild_status": "rebuilt",
+        "status": "rebuilt"
+      },
+      "engine_atomic_ids": [
+        "chamfer",
+        "extrude_add_two_sided",
+        "extrude_cut_blind",
+        "hole_wizard"
+      ],
+      "has_candidate": true,
+      "sample_id": "00002243",
+      "selection_reasons": [
+        "engine_atomic:chamfer",
+        "engine_atomic:extrude_add_two_sided",
+        "engine_atomic:extrude_cut_blind",
+        "engine_atomic:hole_wizard",
+        "sketch_entity:skCircle",
+        "sketch_entity:skLineSegment",
+        "sketch_entity:skPoint",
+        "source_operation:chamfer",
+        "source_operation:extrude",
+        "source_operation:hole",
+        "source_operation:newSketch"
+      ],
+      "sketch_entities": [
+        "skCircle",
+        "skLineSegment",
+        "skPoint"
+      ],
+      "source_operations": [
+        "chamfer",
+        "extrude",
+        "hole",
+        "newSketch"
+      ],
+      "tiers": [
+        "conversion",
+        "engine"
+      ],
+      "unsupported_capabilities": [],
+      "unsupported_operations": []
+    },
+    {
+      "baseline": {
+        "conversion_status": "deferred_no_executable_feature",
+        "status": "deferred_no_executable_feature"
+      },
+      "engine_atomic_ids": [
+        "extrude_cut_blind",
+        "revolve_add"
+      ],
+      "has_candidate": true,
+      "sample_id": "00035682",
+      "selection_reasons": [
+        "unsupported_capability:reference_plane:line_point"
+      ],
+      "sketch_entities": [
+        "skCircle",
+        "skLineSegment"
+      ],
+      "source_operations": [
+        "cPlane",
+        "extrude",
+        "newSketch",
+        "revolve"
+      ],
+      "tiers": [
+        "conversion"
+      ],
+      "unsupported_capabilities": [
+        "reference_plane:line_point"
+      ],
+      "unsupported_operations": []
+    },
+    {
+      "baseline": {
+        "conversion_status": "deferred_no_executable_feature",
+        "status": "deferred_no_executable_feature"
+      },
+      "engine_atomic_ids": [
+        "extrude_add_blind",
+        "extrude_cut_blind",
+        "revolve_add"
+      ],
+      "has_candidate": true,
+      "sample_id": "00054089",
+      "selection_reasons": [
+        "unsupported_capability:extrude_profile_topology:swept_edge"
+      ],
+      "sketch_entities": [
+        "skArc",
+        "skLineSegment"
+      ],
+      "source_operations": [
+        "extrude",
+        "newSketch",
+        "revolve"
+      ],
+      "tiers": [
+        "conversion"
+      ],
+      "unsupported_capabilities": [
+        "extrude_profile_topology:swept_edge"
+      ],
+      "unsupported_operations": []
+    },
+    {
+      "baseline": {
+        "comparison_decision": "rejected",
+        "conversion_status": "converted_complete",
+        "rebuild_status": "rebuilt",
+        "status": "rebuilt"
+      },
+      "engine_atomic_ids": [
+        "chamfer",
+        "extrude_add_blind",
+        "extrude_add_two_sided",
+        "fillet",
+        "revolve_add"
+      ],
+      "has_candidate": true,
+      "sample_id": "00111611",
+      "selection_reasons": [
+        "engine_atomic:chamfer",
+        "engine_atomic:extrude_add_blind",
+        "engine_atomic:extrude_add_two_sided",
+        "engine_atomic:fillet",
+        "engine_atomic:revolve_add",
+        "sketch_entity:skArc",
+        "sketch_entity:skCircle",
+        "sketch_entity:skLineSegment",
+        "source_operation:chamfer",
+        "source_operation:extrude",
+        "source_operation:fillet",
+        "source_operation:newSketch",
+        "source_operation:revolve"
+      ],
+      "sketch_entities": [
+        "skArc",
+        "skCircle",
+        "skLineSegment"
+      ],
+      "source_operations": [
+        "chamfer",
+        "extrude",
+        "fillet",
+        "newSketch",
+        "revolve"
+      ],
+      "tiers": [
+        "conversion",
+        "engine"
+      ],
+      "unsupported_capabilities": [],
+      "unsupported_operations": []
+    },
+    {
+      "baseline": {
+        "conversion_status": "converted_complete",
+        "rebuild_status": "rebuilt",
+        "status": "rebuilt"
+      },
+      "engine_atomic_ids": [
+        "extrude_cut_blind",
+        "reference_plane",
+        "revolve_add",
+        "revolve_cut"
+      ],
+      "has_candidate": true,
+      "sample_id": "00129362",
+      "selection_reasons": [
+        "engine_atomic:extrude_cut_blind",
+        "engine_atomic:reference_plane",
+        "engine_atomic:revolve_add",
+        "engine_atomic:revolve_cut",
+        "sketch_entity:skArc",
+        "sketch_entity:skCircle",
+        "sketch_entity:skLineSegment",
+        "sketch_entity:skPoint",
+        "source_operation:cPlane",
+        "source_operation:extrude",
+        "source_operation:newSketch",
+        "source_operation:revolve"
+      ],
+      "sketch_entities": [
+        "skArc",
+        "skCircle",
+        "skLineSegment",
+        "skPoint"
+      ],
+      "source_operations": [
+        "cPlane",
+        "extrude",
+        "newSketch",
+        "revolve"
+      ],
+      "tiers": [
+        "conversion",
+        "engine"
+      ],
+      "unsupported_capabilities": [],
+      "unsupported_operations": []
+    },
+    {
+      "baseline": {
+        "conversion_status": "converted_partial",
+        "status": "converted_partial"
+      },
+      "engine_atomic_ids": [
+        "reference_plane",
+        "revolve_add"
+      ],
+      "has_candidate": true,
+      "sample_id": "00159804",
+      "selection_reasons": [
+        "unsupported_capability:extrude_add_through_all"
+      ],
+      "sketch_entities": [
+        "skArc",
+        "skCircle",
+        "skLineSegment"
+      ],
+      "source_operations": [
+        "cPlane",
+        "circularPattern",
+        "extrude",
+        "newSketch",
+        "revolve"
+      ],
+      "tiers": [
+        "conversion"
+      ],
+      "unsupported_capabilities": [
+        "extrude_add_through_all",
+        "reference_plane:line_angle"
+      ],
+      "unsupported_operations": [
+        "circularPattern"
+      ]
+    },
+    {
+      "baseline": {
+        "conversion_status": "converted_partial",
+        "status": "converted_partial"
+      },
+      "engine_atomic_ids": [
+        "extrude_add_blind",
+        "reference_plane"
+      ],
+      "has_candidate": true,
+      "sample_id": "00192744",
+      "selection_reasons": [
+        "unsupported_capability:extrude_extent:up_to_next",
+        "unsupported_capability:reference_plane:curve_point"
+      ],
+      "sketch_entities": [
+        "skCircle",
+        "skLineSegment"
+      ],
+      "source_operations": [
+        "cPlane",
+        "circularPattern",
+        "extrude",
+        "newSketch"
+      ],
+      "tiers": [
+        "conversion"
+      ],
+      "unsupported_capabilities": [
+        "extrude_extent:up_to_next",
+        "reference_plane:curve_point"
+      ],
+      "unsupported_operations": [
+        "circularPattern"
+      ]
+    },
+    {
+      "baseline": {
+        "conversion_status": "converted_partial",
+        "status": "converted_partial"
+      },
+      "engine_atomic_ids": [
+        "extrude_add_blind"
+      ],
+      "has_candidate": true,
+      "sample_id": "00212904",
+      "selection_reasons": [
+        "unsupported_capability:extrude_cut_two_sided",
+        "unsupported_capability:reference_plane:three_point"
+      ],
+      "sketch_entities": [
+        "skLineSegment",
+        "skPoint"
+      ],
+      "source_operations": [
+        "cPlane",
+        "extrude",
+        "newSketch",
+        "shell"
+      ],
+      "tiers": [
+        "conversion"
+      ],
+      "unsupported_capabilities": [
+        "extrude_cut_two_sided",
+        "reference_plane:three_point"
+      ],
+      "unsupported_operations": [
+        "shell"
+      ]
+    },
+    {
+      "baseline": {
+        "conversion_status": "converted_partial",
+        "status": "converted_partial"
+      },
+      "engine_atomic_ids": [
+        "extrude_add_blind"
+      ],
+      "has_candidate": true,
+      "sample_id": "00287955",
+      "selection_reasons": [
+        "sketch_entity:skEllipse",
+        "source_operation:loft",
+        "unsupported_capability:extrude_profile_topology:cap_edge",
+        "unsupported_capability:reference_plane:mid_plane",
+        "unsupported_operation:loft"
+      ],
+      "sketch_entities": [
+        "skEllipse",
+        "skFitSpline",
+        "skLineSegment"
+      ],
+      "source_operations": [
+        "cPlane",
+        "extrude",
+        "loft",
+        "newSketch",
+        "revolve"
+      ],
+      "tiers": [
+        "conversion"
+      ],
+      "unsupported_capabilities": [
+        "extrude_profile_topology:cap_edge",
+        "reference_plane:mid_plane"
+      ],
+      "unsupported_operations": [
+        "loft"
+      ]
+    },
+    {
+      "baseline": {
+        "conversion_status": "converted_partial",
+        "status": "converted_partial"
+      },
+      "engine_atomic_ids": [
+        "extrude_add_blind"
+      ],
+      "has_candidate": true,
+      "sample_id": "00423838",
+      "selection_reasons": [
+        "unsupported_capability:extrude_extent:up_to_vertex"
+      ],
+      "sketch_entities": [
+        "skArc",
+        "skCircle",
+        "skLineSegment"
+      ],
+      "source_operations": [
+        "circularPattern",
+        "extrude",
+        "newSketch"
+      ],
+      "tiers": [
+        "conversion"
+      ],
+      "unsupported_capabilities": [
+        "extrude_cut_two_sided",
+        "extrude_extent:up_to_vertex"
+      ],
+      "unsupported_operations": [
+        "circularPattern"
+      ]
+    },
+    {
+      "baseline": {
+        "conversion_status": "converted_partial",
+        "status": "converted_partial"
+      },
+      "engine_atomic_ids": [
+        "extrude_add_blind"
+      ],
+      "has_candidate": true,
+      "sample_id": "00542223",
+      "selection_reasons": [
+        "sketch_entity:skFitSpline",
+        "source_operation:circularPattern",
+        "source_operation:shell",
+        "source_operation:sweep",
+        "unsupported_capability:extrude_cut_through_all",
+        "unsupported_capability:reference_plane:plane_point",
+        "unsupported_operation:circularPattern",
+        "unsupported_operation:shell",
+        "unsupported_operation:sweep"
+      ],
+      "sketch_entities": [
+        "skCircle",
+        "skFitSpline"
+      ],
+      "source_operations": [
+        "cPlane",
+        "circularPattern",
+        "extrude",
+        "fillet",
+        "newSketch",
+        "shell",
+        "sweep"
+      ],
+      "tiers": [
+        "conversion"
+      ],
+      "unsupported_capabilities": [
+        "extrude_cut_through_all",
+        "reference_plane:plane_point"
+      ],
+      "unsupported_operations": [
+        "circularPattern",
+        "shell",
+        "sweep"
+      ]
+    },
+    {
+      "baseline": {
+        "conversion_status": "converted_partial",
+        "status": "converted_partial"
+      },
+      "engine_atomic_ids": [
+        "reference_plane"
+      ],
+      "has_candidate": true,
+      "sample_id": "00612529",
+      "selection_reasons": [
+        "unsupported_capability:extrude_profile_topology:mid_cap_edge"
+      ],
+      "sketch_entities": [
+        "skFitSpline"
+      ],
+      "source_operations": [
+        "cPlane",
+        "extrude",
+        "loft",
+        "mirror",
+        "newSketch"
+      ],
+      "tiers": [
+        "conversion"
+      ],
+      "unsupported_capabilities": [
+        "extrude_profile_topology:mid_cap_edge"
+      ],
+      "unsupported_operations": [
+        "loft"
+      ]
+    },
+    {
+      "baseline": {
+        "conversion_status": "converted_partial",
+        "status": "converted_partial"
+      },
+      "engine_atomic_ids": [
+        "extrude_add_blind",
+        "fillet"
+      ],
+      "has_candidate": true,
+      "sample_id": "00694309",
+      "selection_reasons": [
+        "unsupported_capability:extrude_extent:up_to_body"
+      ],
+      "sketch_entities": [
+        "skCircle"
+      ],
+      "source_operations": [
+        "extrude",
+        "fillet",
+        "newSketch"
+      ],
+      "tiers": [
+        "conversion"
+      ],
+      "unsupported_capabilities": [
+        "extrude_extent:up_to_body"
+      ],
+      "unsupported_operations": []
+    },
+    {
+      "baseline": {
+        "conversion_status": "converted_partial",
+        "status": "converted_partial"
+      },
+      "engine_atomic_ids": [
+        "extrude_add_blind"
+      ],
+      "has_candidate": true,
+      "sample_id": "00710855",
+      "selection_reasons": [
+        "unsupported_capability:extrude_surface_or_mixed"
+      ],
+      "sketch_entities": [
+        "skCircle"
+      ],
+      "source_operations": [
+        "chamfer",
+        "extrude",
+        "newSketch"
+      ],
+      "tiers": [
+        "conversion"
+      ],
+      "unsupported_capabilities": [
+        "extrude_surface_or_mixed"
+      ],
+      "unsupported_operations": []
+    },
+    {
+      "baseline": {
+        "conversion_status": "converted_partial",
+        "status": "converted_partial"
+      },
+      "engine_atomic_ids": [
+        "extrude_add_blind",
+        "fillet"
+      ],
+      "has_candidate": true,
+      "sample_id": "00789939",
+      "selection_reasons": [
+        "unsupported_capability:extrude_profile_topology:offset_face",
+        "unsupported_capability:extrude_profile_topology:swept_face"
+      ],
+      "sketch_entities": [
+        "skArc",
+        "skCircle",
+        "skLineSegment",
+        "skPoint"
+      ],
+      "source_operations": [
+        "extrude",
+        "fillet",
+        "newSketch",
+        "shell"
+      ],
+      "tiers": [
+        "conversion"
+      ],
+      "unsupported_capabilities": [
+        "extrude_profile_topology:offset_face",
+        "extrude_profile_topology:swept_face"
+      ],
+      "unsupported_operations": [
+        "shell"
+      ]
+    },
+    {
+      "baseline": {
+        "conversion_status": "converted_partial",
+        "status": "converted_partial"
+      },
+      "engine_atomic_ids": [
+        "extrude_add_blind"
+      ],
+      "has_candidate": true,
+      "sample_id": "00835610",
+      "selection_reasons": [
+        "source_operation:booleanBodies",
+        "unsupported_capability:extrude_profile_topology:cap_face",
+        "unsupported_capability:extrude_profile_topology:intersect",
+        "unsupported_capability:revolve_surface",
+        "unsupported_operation:booleanBodies"
+      ],
+      "sketch_entities": [
+        "skCircle",
+        "skLineSegment",
+        "skPoint"
+      ],
+      "source_operations": [
+        "booleanBodies",
+        "extrude",
+        "newSketch",
+        "revolve"
+      ],
+      "tiers": [
+        "conversion"
+      ],
+      "unsupported_capabilities": [
+        "extrude_profile_topology:cap_face",
+        "extrude_profile_topology:intersect",
+        "revolve_surface"
+      ],
+      "unsupported_operations": [
+        "booleanBodies"
+      ]
+    },
+    {
+      "baseline": {
+        "conversion_status": "converted_partial",
+        "status": "converted_partial"
+      },
+      "engine_atomic_ids": [
+        "extrude_add_blind",
+        "pattern_mirror",
+        "reference_plane"
+      ],
+      "has_candidate": true,
+      "sample_id": "00925274",
+      "selection_reasons": [
+        "engine_atomic:pattern_mirror",
+        "source_operation:mirror",
+        "unsupported_capability:extrude_extent:up_to_surface",
+        "unsupported_capability:reference_plane:line_angle"
+      ],
+      "sketch_entities": [
+        "skCircle",
+        "skLineSegment"
+      ],
+      "source_operations": [
+        "cPlane",
+        "extrude",
+        "mirror",
+        "newSketch"
+      ],
+      "tiers": [
+        "conversion"
+      ],
+      "unsupported_capabilities": [
+        "extrude_cut_through_all",
+        "extrude_extent:up_to_surface",
+        "reference_plane:line_angle"
+      ],
+      "unsupported_operations": []
+    }
+  ],
+  "feature_inventory": {
+    "engine_atomic": {
+      "chamfer": 1011,
+      "extrude_add_blind": 6215,
+      "extrude_add_two_sided": 924,
+      "extrude_cut_blind": 1302,
+      "fillet": 2292,
+      "hole_wizard": 343,
+      "pattern_mirror": 152,
+      "reference_plane": 1023,
+      "revolve_add": 1062,
+      "revolve_cut": 99
+    },
+    "sketch_entity": {
+      "skArc": 2777,
+      "skCircle": 5556,
+      "skEllipse": 131,
+      "skFitSpline": 897,
+      "skLineSegment": 7962,
+      "skPoint": 4419
+    },
+    "source_operation": {
+      "booleanBodies": 187,
+      "cPlane": 1188,
+      "chamfer": 1432,
+      "circularPattern": 232,
+      "extrude": 8238,
+      "fillet": 3639,
+      "hole": 894,
+      "loft": 309,
+      "mirror": 411,
+      "newSketch": 9347,
+      "revolve": 1798,
+      "shell": 696,
+      "sweep": 326
+    },
+    "unsupported_capability": {
+      "extrude_add_through_all": 4,
+      "extrude_cut_through_all": 303,
+      "extrude_cut_two_sided": 262,
+      "extrude_extent:up_to_body": 2,
+      "extrude_extent:up_to_next": 49,
+      "extrude_extent:up_to_surface": 95,
+      "extrude_extent:up_to_vertex": 4,
+      "extrude_profile_topology:cap_edge": 133,
+      "extrude_profile_topology:cap_face": 200,
+      "extrude_profile_topology:intersect": 382,
+      "extrude_profile_topology:mid_cap_edge": 2,
+      "extrude_profile_topology:offset_face": 18,
+      "extrude_profile_topology:swept_edge": 16,
+      "extrude_profile_topology:swept_face": 99,
+      "extrude_surface_or_mixed": 4,
+      "reference_plane:curve_point": 13,
+      "reference_plane:line_angle": 123,
+      "reference_plane:line_point": 23,
+      "reference_plane:mid_plane": 25,
+      "reference_plane:plane_point": 47,
+      "reference_plane:three_point": 35,
+      "revolve_surface": 367
+    },
+    "unsupported_operation": {
+      "booleanBodies": 187,
+      "circularPattern": 232,
+      "loft": 309,
+      "shell": 696,
+      "sweep": 326
+    }
+  },
+  "schema": "cadfs_to_cdsl.regression.v1",
+  "selected_ids": [
+    "00002243",
+    "00035682",
+    "00054089",
+    "00111611",
+    "00129362",
+    "00159804",
+    "00192744",
+    "00212904",
+    "00287955",
+    "00423838",
+    "00542223",
+    "00612529",
+    "00694309",
+    "00710855",
+    "00789939",
+    "00835610",
+    "00925274"
+  ],
+  "selected_sample_count": 17,
+  "source_output": "cadfs_to_cdsl/output",
+  "source_sample_count": 9347
+}
diff --git a/cadfs_to_cdsl/reports.py b/cadfs_to_cdsl/reports.py
index 53543bb9..c72ad908 100644
--- a/cadfs_to_cdsl/reports.py
+++ b/cadfs_to_cdsl/reports.py
@@ -184,11 +184,12 @@ def generate_markdown_report(
     )
 
     unsupported_ops = {
-        "shell", "loft", "sweep", "draft", "thicken", "split", "booleanBodies", "circularPattern",
+        "shell", "sweep", "draft", "thicken", "split", "booleanBodies", "circularPattern",
         "moveFace", "replaceFace", "deleteFace", "import", "derive",
     }
     exact_mappings = {
         "extrude": "extrude_add_blind / extrude_add_two_sided / extrude_cut_blind",
+        "loft": "loft_add (simple closed sketch profiles only)",
         "revolve": "revolve_add / revolve_cut",
         "fillet": "fillet",
         "chamfer": "chamfer",
diff --git a/cadfs_to_cdsl/selector_binding.py b/cadfs_to_cdsl/selector_binding.py
index 93ab6ef0..7baafa3c 100644
--- a/cadfs_to_cdsl/selector_binding.py
+++ b/cadfs_to_cdsl/selector_binding.py
@@ -14,6 +14,12 @@ def _score(expected: dict[str, Any], actual: dict[str, Any]) -> float | None:
             left, right = expected[key], actual.get(key)
             if not isinstance(right, (list, tuple)) or len(left) != len(right): return None
             delta = math.sqrt(sum((float(a) - float(b)) ** 2 for a, b in zip(left, right)))
+            if key == "normal":
+                # A source CAP_FACE identifies a geometric plane, not the OCC
+                # orientation of the resulting face.  The two kernels may
+                # report the same cap with inverse normals, especially for a
+                # start cap.  Keep axis direction orientation-sensitive.
+                delta = min(delta, math.sqrt(sum((float(a) + float(b)) ** 2 for a, b in zip(left, right))))
             scores.append(max(0.0, 1.0 - delta / 0.05))
     for key in ("radius_mm", "plane_offset_mm"):
         if key in expected:
@@ -75,7 +81,16 @@ def bind_candidate_selectors(cdsl: dict[str, Any]) -> tuple[dict[str, Any], list
             if not prefix["features"]: raise ValueError(f"{feature['id']}: selector has no executable prefix")
             report = rebuild_cdsl(prefix, Path(temporary) / f"prefix-{index}.step", strict=True)
             body_id = next((item.get("body_id") for item in reversed(report.get("feature_results") or []) if item.get("body_id")), None)
-            records = [item for item in report.get("topology_records") or [] if not body_id or item.get("body_id") == body_id or str(item.get("body_id") or "").startswith(f"{body_id}:")]
+            records = [
+                item for item in report.get("topology_records") or []
+                # Reference planes and axes are session context, not body
+                # topology. They must remain available while binding a mirror
+                # or extent selector against a body-bearing prefix.
+                if item.get("kind") in {"plane", "axis"}
+                or not body_id
+                or item.get("body_id") == body_id
+                or str(item.get("body_id") or "").startswith(f"{body_id}:")
+            ]
             resolved = []
             for placeholder in placeholders:
                 geometry = placeholder.get("geometry") or {}
@@ -85,14 +100,21 @@ def bind_candidate_selectors(cdsl: dict[str, Any]) -> tuple[dict[str, Any], list
                     owner = placeholder.get("owner_feature_id")
                     owner_matches = [record for record in same_kind if owner in (record.get("owner_feature_ids") or [record.get("feature_id")])]
                     pool = owner_matches or same_kind
-                    if not geometry and len(pool) != 1:
-                        raise ValueError(f"{feature['id']}: selector_ambiguous after prefix rebuild")
-                    scored = [(score, record) for record in pool if (score := _score(geometry, record.get("geometry") or {})) is not None and score >= 0.8]
-                    scored.sort(key=lambda value: (-value[0], str(value[1].get("record_id"))))
-                    if scored:
-                        if len(scored) > 1 and abs(scored[0][0] - scored[1][0]) <= 1e-9:
+                    if not geometry:
+                        # Context selectors (notably a generated mirror plane)
+                        # may have no geometric snapshot. Their owner-qualified
+                        # singleton identity is sufficient and must not be scored
+                        # as a zero-information geometric match.
+                        if len(pool) != 1:
                             raise ValueError(f"{feature['id']}: selector_ambiguous after prefix rebuild")
-                        candidates = [scored[0][1]]
+                        candidates = [pool[0]]
+                    else:
+                        scored = [(score, record) for record in pool if (score := _score(geometry, record.get("geometry") or {})) is not None and score >= 0.8]
+                        scored.sort(key=lambda value: (-value[0], str(value[1].get("record_id"))))
+                        if scored:
+                            if len(scored) > 1 and abs(scored[0][0] - scored[1][0]) <= 1e-9:
+                                raise ValueError(f"{feature['id']}: selector_ambiguous after prefix rebuild")
+                            candidates = [scored[0][1]]
                 if not candidates: raise ValueError(f"{feature['id']}: selector_not_found after prefix rebuild")
                 for record in candidates:
                     owners = record.get("owner_feature_ids") or [record.get("feature_id")]
diff --git a/cadfs_to_cdsl/tests/test_lowering.py b/cadfs_to_cdsl/tests/test_lowering.py
index 6f958a82..6ca5cc11 100644
--- a/cadfs_to_cdsl/tests/test_lowering.py
+++ b/cadfs_to_cdsl/tests/test_lowering.py
@@ -7,7 +7,7 @@ from cadfs_to_cdsl.lowering import lower_model
 from cadfs_to_cdsl.pipeline import convert_one
 from cadfs_to_cdsl.dataset import Sample
 from cadfs_to_cdsl.dataset import scan_dataset
-from cadfs_to_cdsl.tests.test_parser import SOURCE
+from cadfs_to_cdsl.tests.test_parser import SOURCE, TRANSFORM_SOURCE
 
 
 class LoweringTests(unittest.TestCase):
@@ -30,12 +30,61 @@ class LoweringTests(unittest.TestCase):
         self.assertIsNone(result.cdsl)
         self.assertEqual(result.diagnostics[0]["code"], "unsupported_operation")
 
-    def test_symmetric_cut_is_not_disguised_as_blind_cut(self):
+    def test_direct_translation_transform_is_baked_into_the_source_feature(self):
+        result = lower_model(parse_featurescript(TRANSFORM_SOURCE, "transform"), {})
+        self.assertEqual(result.status, "converted_complete")
+        self.assertEqual([item["id"] for item in result.cdsl["features"]], ["f_F1"])
+        self.assertEqual(result.history[-1]["feature_id"], "F2")
+        self.assertFalse(result.diagnostics)
+        self.assertEqual(result.cdsl["geometry"]["sketches"][0]["workplane"]["origin_mm"], [10.0, 0.0, 0.0])
+
+    def test_copy_transform_remains_an_explicit_engine_capability_gap(self):
+        source = TRANSFORM_SOURCE.replace('"makeCopy":false', '"makeCopy":true')
+        result = lower_model(parse_featurescript(source, "transform-copy"), {})
+        self.assertEqual(result.status, "converted_partial")
+        self.assertEqual(result.diagnostics[-1]["code"], "unsupported_engine_capability")
+        self.assertEqual(result.diagnostics[-1]["capability"], "transform")
+
+    def test_symmetric_cut_lowers_to_two_sided_cut(self):
         source = SOURCE.replace('"depth":120 * mm', '"operationType":NewBodyOperationType.REMOVE, "depth":120 * mm, "symmetric":true')
         result = lower_model(parse_featurescript(source, "symmetric-cut"), {})
-        self.assertIsNone(result.cdsl)
-        self.assertEqual(result.diagnostics[0]["code"], "unsupported_engine_capability")
-        self.assertEqual(result.diagnostics[0]["capability"], "extrude_cut_two_sided")
+        self.assertEqual(result.status, "converted_complete")
+        feature = result.cdsl["features"][0]
+        self.assertEqual(feature["atomic_id"], "extrude_cut_two_sided")
+        self.assertEqual(feature["params"]["distance_mm"], 60.0)
+        self.assertEqual(feature["params"]["reverse_distance_mm"], 60.0)
+
+    def test_through_all_extrudes_reuse_the_engine_extent_contract(self):
+        for operation_type, expected_atomic in [
+            ("NewBodyOperationType.NEW", "extrude_add_blind"),
+            ("NewBodyOperationType.REMOVE", "extrude_cut_blind"),
+        ]:
+            with self.subTest(operation_type=operation_type):
+                source = SOURCE.replace(
+                    '"depth":120 * mm',
+                    f'"operationType":{operation_type}, "depth":120 * mm, "endBound":BoundingType.THROUGH_ALL',
+                )
+                result = lower_model(parse_featurescript(source, f"through-all-{operation_type}"), {})
+                self.assertEqual(result.status, "converted_complete")
+                feature = result.cdsl["features"][0]
+                self.assertEqual(feature["atomic_id"], expected_atomic)
+                self.assertEqual(feature["params"]["end_condition"]["type"], "through_all")
+
+    def test_up_to_next_extrudes_reuse_the_engine_extent_contract(self):
+        for operation_type, expected_atomic in [
+            ("NewBodyOperationType.NEW", "extrude_add_blind"),
+            ("NewBodyOperationType.REMOVE", "extrude_cut_blind"),
+        ]:
+            with self.subTest(operation_type=operation_type):
+                source = SOURCE.replace(
+                    '"depth":120 * mm',
+                    f'"operationType":{operation_type}, "depth":120 * mm, "endBound":BoundingType.UP_TO_NEXT',
+                )
+                result = lower_model(parse_featurescript(source, f"up-to-next-{operation_type}"), {})
+                self.assertEqual(result.status, "converted_complete")
+                feature = result.cdsl["features"][0]
+                self.assertEqual(feature["atomic_id"], expected_atomic)
+                self.assertEqual(feature["params"]["end_condition"]["type"], "through_next")
 
     def test_open_nonconstruction_geometry_is_not_silently_dropped(self):
         source = SOURCE.replace('skSolve(sketch);', 'skLineSegment(sketch, "open", {"start":v(0, 0) * mm, "end":v(20, 0) * mm}); skSolve(sketch);', 1)
@@ -53,6 +102,83 @@ class LoweringTests(unittest.TestCase):
         self.assertEqual(gap["capability"], "revolve_surface")
         self.assertIsNone(result.cdsl)
 
+    def test_fit_spline_loft_lowers_to_executable_loft_add(self):
+        root = Path(__file__).parents[2] / "data/cadfs-sample/CADFS_test"
+        feature = root / "featurescript_rp/0061/00612529.txt"
+        if not feature.exists(): self.skipTest("CADFS sample is not installed")
+        result = lower_model(parse_featurescript(feature.read_text(), "00612529"), {})
+        self.assertIsNotNone(result.cdsl)
+        features = {item["id"]: item for item in result.cdsl["features"]}
+        self.assertEqual(features["f_F3"]["atomic_id"], "loft_add")
+        self.assertEqual(features["f_F3"]["params"]["profile_sketch_ids"], ["sketch_F2", "sketch_F0"])
+        self.assertEqual(features["f_F4"]["atomic_id"], "pattern_mirror")
+        self.assertEqual(features["f_F4"]["params"]["source_feature_ids"], ["f_F3"])
+        sketches = {item["id"]: item for item in result.cdsl["geometry"]["sketches"]}
+        self.assertEqual(sketches["sketch_F0"]["profile"]["contours"][0]["segments"][0]["type"], "bspline")
+        self.assertNotIn("loft", {item.get("operation") for item in result.diagnostics})
+
+    def test_fit_spline_loft_candidate_rebuilds(self):
+        root = Path(__file__).parents[2] / "data/cadfs-sample/CADFS_test"
+        feature = root / "featurescript_rp/0061/00612529.txt"
+        if not feature.exists(): self.skipTest("CADFS sample is not installed")
+        result = lower_model(parse_featurescript(feature.read_text(), "00612529"), {})
+        with tempfile.TemporaryDirectory() as tmp:
+            from cadfs_to_cdsl.rebuild import rebuild_candidate
+            rebuilt = rebuild_candidate(result.cdsl, Path(tmp) / "rebuilt.step")
+            self.assertEqual(rebuilt["status"], "rebuilt")
+            self.assertGreater(rebuilt["result"]["volume_mm3"], 0)
+
+    def test_direct_translation_transform_updates_the_source_revolve(self):
+        root = Path(__file__).parents[2] / "data/cadfs-sample/CADFS_test"
+        feature = root / "featurescript_rp/0011/00111611.txt"
+        if not feature.exists(): self.skipTest("CADFS sample is not installed")
+        result = lower_model(parse_featurescript(feature.read_text(), "00111611"), {})
+        self.assertNotIn("F10", {item.get("feature_id") for item in result.diagnostics})
+        features = {item["id"]: item for item in result.cdsl["features"]}
+        sketches = {item["id"]: item for item in result.cdsl["geometry"]["sketches"]}
+        self.assertEqual(sketches[features["f_F9"]["sketch_id"]]["workplane"]["origin_mm"], [77.16, -11.67, -63.0])
+        for actual, expected in zip(features["f_F9"]["params"]["axis"]["origin_mm"], [0.13, -11.67, 56.11]):
+            self.assertAlmostEqual(actual, expected)
+
+    def test_circular_pattern_lowers_to_existing_engine_contract(self):
+        root = Path(__file__).parents[2] / "data/cadfs-sample/CADFS_test"
+        feature = root / "featurescript_rp/0042/00423838.txt"
+        if not feature.exists(): self.skipTest("CADFS sample is not installed")
+        result = lower_model(parse_featurescript(feature.read_text(), "00423838"), {})
+        self.assertIsNotNone(result.cdsl)
+        features = {item["id"]: item for item in result.cdsl["features"]}
+        pattern = features["f_F4"]
+        self.assertEqual(pattern["atomic_id"], "pattern_circular")
+        self.assertEqual(pattern["params"]["source_feature_ids"], ["f_F1"])
+        self.assertEqual(pattern["params"]["pattern_count"], 6)
+        self.assertEqual(pattern["params"]["sweep_angle_deg"], 360.0)
+        self.assertEqual(pattern["params"]["axis"]["direction"], [0.0, 0.0, -1.0])
+        self.assertNotIn("F2", {item.get("feature_id") for item in result.diagnostics})
+        sketches = {item["id"]: item for item in result.cdsl["geometry"]["sketches"]}
+        self.assertNotEqual(sketches["sketch_F0"]["workplane"]["normal"], [0.0, 0.0, 1.0])
+        self.assertNotIn("circularPattern", {item.get("operation") for item in result.diagnostics})
+
+    def test_reference_plane_variants_lower_to_explicit_frames(self):
+        root = Path(__file__).parents[2] / "data/cadfs-sample/CADFS_test"
+        cases = {
+            "00159804": {"F3", "F5"},
+            "00192744": {"F3"},
+            "00212904": {"F3"},
+            "00542223": {"F3"},
+        }
+        for sample_id, expected in cases.items():
+            with self.subTest(sample_id=sample_id):
+                feature = root / "featurescript_rp" / sample_id[:4] / f"{sample_id}.txt"
+                if not feature.exists(): self.skipTest("CADFS sample is not installed")
+                result = lower_model(parse_featurescript(feature.read_text(), sample_id), {})
+                features = {item["name"]: item for item in result.cdsl["features"]}
+                for feature_id in expected:
+                    plane = features[feature_id]
+                    self.assertEqual(plane["atomic_id"], "reference_plane")
+                    self.assertEqual(set(plane["params"]["plane"]), {"origin_mm", "x_dir", "normal"})
+                diagnostics = [item for item in result.diagnostics if item.get("operation") == "cPlane"]
+                self.assertFalse(diagnostics)
+
     def test_feature_face_profile_is_not_reused_as_original_sketch(self):
         source = SOURCE.replace('qSketchRegion(id + "F0", true)', 'makeQuery(id+"F1.opExtrude","CAP_FACE",FACE,{"isStart":false})')
         result = lower_model(parse_featurescript(source, "face-profile"), {})
diff --git a/cadfs_to_cdsl/tests/test_parser.py b/cadfs_to_cdsl/tests/test_parser.py
index a420fd82..127197ad 100644
--- a/cadfs_to_cdsl/tests/test_parser.py
+++ b/cadfs_to_cdsl/tests/test_parser.py
@@ -19,6 +19,14 @@ export const f = defineFeature(function(context, id, definition) {
 });
 '''
 
+TRANSFORM_SOURCE = SOURCE.replace(
+    '\n});\n',
+    '''
+  transform(context, id + "F2", {"entities":qCreatedBy(id + "F1", BODY), "transformType":TransformType.TRANSLATION_3D, "dx":10 * mm, "dy":0 * mm, "dz":0 * mm, "makeCopy":false});
+});
+''',
+)
+
 
 class ParserTests(unittest.TestCase):
     def test_lexer_ignores_comments_and_preserves_lines(self):
@@ -32,6 +40,12 @@ class ParserTests(unittest.TestCase):
         self.assertEqual(model.sketches[0].entities[0].operation, "skCircle")
         self.assertIsInstance(model.features[0].params["entities"], Call)
 
+    def test_transform_is_preserved_as_a_feature(self):
+        model = parse_featurescript(TRANSFORM_SOURCE, "transform")
+        self.assertEqual([step.feature_id for step in model.steps], ["F0", "F1", "F2"])
+        self.assertEqual(model.features[-1].operation, "transform")
+        self.assertEqual(model.features[-1].params["transformType"], "TransformType.TRANSLATION_3D")
+
     def test_query_parser(self):
         query = Call("makeQuery", [Call("__binary__", ["id", "+", "F1.opExtrude"]), "CAP_EDGE", "EDGE", {"isStart": False, "x": Call("sQuery", [Call("__binary__", ["id", "+", "F0.wireOp"]), "EDGE", "E0"])}])
         value = parse_query(query)
diff --git a/cadfs_to_cdsl/tests/test_regression.py b/cadfs_to_cdsl/tests/test_regression.py
new file mode 100644
index 00000000..6986efa3
--- /dev/null
+++ b/cadfs_to_cdsl/tests/test_regression.py
@@ -0,0 +1,73 @@
+from __future__ import annotations
+
+import json
+import tempfile
+import unittest
+from pathlib import Path
+
+from cadfs_to_cdsl.regression import build_regression_manifest, regression_sample_ids
+
+
+class RegressionSelectionTests(unittest.TestCase):
+    def _sample(
+        self,
+        root: Path,
+        sample_id: str,
+        *,
+        operation: str,
+        entity: str | None = None,
+        atomic: str | None = None,
+        capability: str | None = None,
+        rebuilt: bool = False,
+    ) -> None:
+        directory = root / "samples" / sample_id
+        directory.mkdir(parents=True)
+        history = [{"operation": operation}]
+        if entity:
+            history[0]["entities"] = [{"operation": entity}]
+        (directory / "history.json").write_text(json.dumps(history), encoding="utf-8")
+        if atomic:
+            (directory / "candidate.cdsl.json").write_text(json.dumps({"features": [{"atomic_id": atomic}]}), encoding="utf-8")
+        diagnostics = [] if not capability else [{"code": "unsupported_engine_capability", "capability": capability}]
+        (directory / "diagnostics.json").write_text(json.dumps(diagnostics), encoding="utf-8")
+        status = {"status": "rebuilt_approximate" if rebuilt else "converted_partial"}
+        if rebuilt:
+            status["rebuild_status"] = "rebuilt"
+        (directory / "status.json").write_text(json.dumps(status), encoding="utf-8")
+
+    def test_manifest_covers_every_observed_signal_and_keeps_engine_pool_buildable(self) -> None:
+        with tempfile.TemporaryDirectory() as temporary:
+            output = Path(temporary)
+            self._sample(output, "00000001", operation="extrude", entity="skLineSegment", atomic="extrude_add_blind", rebuilt=True)
+            self._sample(output, "00000002", operation="loft", entity="skFitSpline", capability="loft")
+            self._sample(output, "00000003", operation="revolve", entity="skCircle", atomic="revolve_add", rebuilt=True)
+
+            manifest = build_regression_manifest(output)
+
+        self.assertEqual(manifest["selected_ids"], ["00000001", "00000002", "00000003"])
+        self.assertEqual(set(manifest["coverage"]), {
+            "engine_atomic:extrude_add_blind", "engine_atomic:revolve_add",
+            "sketch_entity:skCircle", "sketch_entity:skFitSpline", "sketch_entity:skLineSegment",
+            "source_operation:extrude", "source_operation:loft", "source_operation:revolve",
+            "unsupported_capability:loft",
+        })
+        self.assertEqual(regression_sample_ids_from_manifest(manifest, "engine"), ["00000001", "00000003"])
+        self.assertEqual(manifest["engine_baseline_atomic_ids"], ["extrude_add_blind", "revolve_add"])
+        self.assertEqual(manifest["engine_diagnostic_only_atomic_ids"], [])
+
+    def test_manifest_reader_rejects_unknown_tier(self) -> None:
+        with tempfile.TemporaryDirectory() as temporary:
+            root = Path(temporary)
+            self._sample(root, "00000001", operation="extrude", atomic="extrude_add_blind", rebuilt=True)
+            manifest_path = root / "manifest.json"
+            manifest_path.write_text(json.dumps(build_regression_manifest(root)), encoding="utf-8")
+            self.assertEqual(regression_sample_ids(manifest_path, "engine"), ["00000001"])
+            with self.assertRaisesRegex(ValueError, "Unknown regression tier"):
+                regression_sample_ids(manifest_path, "not-a-tier")
+
+
+def regression_sample_ids_from_manifest(manifest: dict, tier: str) -> list[str]:
+    return sorted(
+        entry["sample_id"] for entry in manifest["entries"]
+        if tier == "all" or tier in entry["tiers"]
+    )
diff --git a/cadfs_to_cdsl/tests/test_selector_binding.py b/cadfs_to_cdsl/tests/test_selector_binding.py
new file mode 100644
index 00000000..33fc7ca2
--- /dev/null
+++ b/cadfs_to_cdsl/tests/test_selector_binding.py
@@ -0,0 +1,24 @@
+from __future__ import annotations
+
+import unittest
+
+from cadfs_to_cdsl.selector_binding import _score
+
+
+class SelectorBindingTests(unittest.TestCase):
+    def test_face_normal_match_is_orientation_independent(self) -> None:
+        score = _score(
+            {"normal": [0.0, 0.0, 1.0], "plane_offset_mm": 12.0},
+            {"normal": [0.0, 0.0, -1.0], "plane_offset_mm": 12.0},
+        )
+        self.assertEqual(score, 1.0)
+
+    def test_axis_direction_remains_orientation_sensitive(self) -> None:
+        score = _score(
+            {"axis_direction": [0.0, 0.0, 1.0]},
+            {"axis_direction": [0.0, 0.0, -1.0]},
+        )
+        self.assertEqual(score, 0.0)
+
+    def test_empty_snapshot_score_is_not_treated_as_a_match(self) -> None:
+        self.assertEqual(_score({}, {"normal": [0.0, 0.0, 1.0]}), 0.0)
diff --git a/json_to_cdsl/output/corpus-manifest.json b/json_to_cdsl/output/corpus-manifest.json
index 8db24cc1..27917825 100644
--- a/json_to_cdsl/output/corpus-manifest.json
+++ b/json_to_cdsl/output/corpus-manifest.json
@@ -5,16 +5,16 @@
   "document_stems_sha256": "ba5b905191817cd0f7b9ad07d4002ad27730e200a395f71f9c4e31ebb1867cd6",
   "phase_pools": {
     "p3": {
-      "selector_count": 770,
-      "selectors_sha256": "7b0e2142effc71bf2e3011654f020062665103cad5a6e219a323d1ee17887c89"
+      "selector_count": 771,
+      "selectors_sha256": "72093701357cd1858f2dbcc0f1ab9e6c7baea7db26357154e0586e5e1be6f801"
     },
     "p4": {
-      "selector_count": 825,
-      "selectors_sha256": "fa9bce14dc72170bd92ea8cb274490e1df733a85a8647de5f13cc39d8b1e945d"
+      "selector_count": 826,
+      "selectors_sha256": "ab9ea6edd8532ce7a0110d0725b5303c63a53617a0af502101b12f657285d371"
     },
     "p6": {
-      "selector_count": 892,
-      "selectors_sha256": "4f925d00636f471f517ccfbd1c030bc6fda8fa172332399964d80618f698ce89"
+      "selector_count": 893,
+      "selectors_sha256": "ac9f91b690bc533b1fdd1772d65ee77b248d108f39a429615d909b78332d9a08"
     }
   }
 }