提交关于N5功能，“involute_gear渐开线齿廓与齿条专用生成”的改动

backend/agent/skills/cdsl-author-guidance/manifest.json

@@ -23,7 +23,9 @@
     {"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-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}
+    {"id": "op-thread", "file": "op-thread.md", "title": "Operation Appendix Thread", "priority": 100, "mandatory": true},
+    {"id": "op-bend", "file": "op-bend.md", "title": "Operation Appendix Bend", "priority": 100, "mandatory": true},
+    {"id": "op-gear", "file": "op-gear.md", "title": "Operation Appendix Gear", "priority": 100, "mandatory": true}
   ],
   "phase_sections": {
     "DEFAULT": ["00-author-contract", "03-coordinate-system-and-datums", "09-evidence-visual-review-and-validation"],
@@ -62,6 +64,9 @@
     "box_add": ["op-primitives"],
     "cylinder_add": ["op-primitives"],
     "thread_add": ["op-thread"],
-    "thread_cut": ["op-thread"]
+    "thread_cut": ["op-thread"],
+    "bend_add": ["op-bend"],
+    "gear_add": ["op-gear"],
+    "rack_add": ["op-gear"]
   }
 }

backend/agent/skills/cdsl-author-guidance/op-bend.md

@@ -0,0 +1 @@
+`bend_add` 以中面折线链定义等厚钣金折弯：正的 `thickness_mm`、`width_mm` 和至少一翼的 `chain`；非末翼必须给 `bend_angle_deg`（内角，0 < angle < 180，90 为直角折弯），可选 `inner_radius_mm`（>= 0，外半径恒为内半径加板厚）与 `side`（+1 / -1，折弯方向）。`frame` 可选，缺省为世界 XY 平面（首翼沿 +X，厚度沿法向）。相邻折弯圆角会消耗直段长度（约 `inner_radius + thickness/2` 的切线距离），每翼剩余直段必须为正，否则规格非法。仅用于意图明确的钣金折弯；单翼链退化为平板，普通平板轮廓应保留草图历史表达而非用 bend_add 替代。

backend/agent/skills/cdsl-author-guidance/op-gear.md

@@ -0,0 +1 @@
+`gear_add` 与 `rack_add` 是渐开线齿轮/齿条的原生图元：正的 `module_mm`、`teeth_count`（齿轮 8–200，齿条 1–2000）与明确的 `axis`。齿轮 `axis.origin_mm` 是 `z=0` 端面圆心、`axis.direction` 为齿轴；齿条 `axis.direction` 是齿的伸出方向、`axis.origin_mm` 是长度起点端面与厚度起始面及齿谷平面的交点，有效长度精确等于 `teeth_count * pi * module`。`helix_angle_rad > 0` 生成斜齿（螺旋沿轴推进）；加 `herringbone: true` 得到人字齿（双螺旋在齿宽中点对称反转，无退刀槽）。齿数低于 17 时存在根切风险，引擎照常生成并附诊断说明，不静默修正；如需无根切请提高齿数或改用变位设计（当前不支持变位）。齿轮孔、键槽等后续特征用 hole/extrude_cut 沿同一 axis 叠加。