diff --git a/apps/solvecraft-cli/tests/corpus/README.md b/apps/solvecraft-cli/tests/corpus/README.md
index 4dd6ccfe..7e26db03 100644
--- a/apps/solvecraft-cli/tests/corpus/README.md
+++ b/apps/solvecraft-cli/tests/corpus/README.md
@@ -16,6 +16,7 @@ hostile variants of it never panic.
 | `modern-path-pattern` | bd98035 | pattern on path (oracle 53) |
 | `modern-plastic` | bd98035 | shell, lip, boss, rest, snap fit, plastic rule |
 | `naming-split-pieces` | 9a979cf | format 13 names: a slot splits the top; fillet, chamfer and offset face name its pieces by number (`F2:top#2`) |
+| `split-body-pieces` | v0.3.2 (07e263d) | a slot along X cuts a block into two bodies; a fillet, a chamfer and an appearance refer to the pieces by body name (`Body1`, `Body1 (1)`) |
 
 The scripts that made them are in `scripts/`. Never regenerate a file with a newer build: the
 point is that it was written by the old one. Add new files for new eras instead.
diff --git a/apps/solvecraft-cli/tests/corpus/scripts/split-body-pieces.json b/apps/solvecraft-cli/tests/corpus/scripts/split-body-pieces.json
new file mode 100644
index 00000000..987c4dec
--- /dev/null
+++ b/apps/solvecraft-cli/tests/corpus/scripts/split-body-pieces.json
@@ -0,0 +1,107 @@
+{
+ "commands": [
+  {
+   "command": "sketch.create",
+   "params": {
+    "plane": "XY",
+    "name": "Base"
+   }
+  },
+  {
+   "command": "sketch.rectangle.two_point",
+   "params": {
+    "p0": [
+     0,
+     0
+    ],
+    "p1": [
+     40,
+     30
+    ]
+   }
+  },
+  {
+   "command": "sketch.finish",
+   "params": {}
+  },
+  {
+   "command": "solid.extrude",
+   "params": {
+    "distance": 10,
+    "name": "Block"
+   }
+  },
+  {
+   "command": "sketch.create",
+   "params": {
+    "plane": "XY",
+    "name": "SlotSketch"
+   }
+  },
+  {
+   "command": "sketch.rectangle.two_point",
+   "params": {
+    "p0": [
+     -5,
+     12
+    ],
+    "p1": [
+     45,
+     18
+    ]
+   }
+  },
+  {
+   "command": "sketch.finish",
+   "params": {}
+  },
+  {
+   "command": "solid.extrude",
+   "params": {
+    "sketch": "SlotSketch",
+    "distance": 10,
+    "operation": "cut",
+    "name": "Slot"
+   }
+  },
+  {
+   "command": "solid.fillet",
+   "params": {
+    "edges": [
+     [
+      20,
+      0,
+      10
+     ]
+    ],
+    "radius": 2,
+    "body": "Body1 (1)",
+    "name": "NearRound"
+   }
+  },
+  {
+   "command": "solid.chamfer",
+   "params": {
+    "edges": [
+     [
+      20,
+      30,
+      10
+     ]
+    ],
+    "distance": 1.5,
+    "body": "Body1",
+    "name": "FarBevel"
+   }
+  },
+  {
+   "command": "appearance.assign",
+   "params": {
+    "bodies": [
+     "Body1 (1)"
+    ],
+    "color": "#cc3333"
+   }
+  }
+ ]
+}
\ No newline at end of file
diff --git a/apps/solvecraft-cli/tests/corpus/split-body-pieces.expected.json b/apps/solvecraft-cli/tests/corpus/split-body-pieces.expected.json
new file mode 100644
index 00000000..2b1ddfdd
--- /dev/null
+++ b/apps/solvecraft-cli/tests/corpus/split-body-pieces.expected.json
@@ -0,0 +1,171 @@
+{
+  "bodies": [
+    {
+      "area_mm2": 1962.6028137423857,
+      "bbox": {
+        "max": [
+          40.0,
+          30.0,
+          10.0
+        ],
+        "min": [
+          0.0,
+          18.0,
+          0.0
+        ]
+      },
+      "center_of_mass": [
+        20.0,
+        23.94794952681388,
+        4.957413249211356
+      ],
+      "density_g_cm3": 1.29,
+      "edges": 15,
+      "face_types": {
+        "plane": 7
+      },
+      "faces": 7,
+      "kernel": {
+        "edges": 15,
+        "faces": 7,
+        "shells": 1,
+        "vertices": 10
+      },
+      "mass_g": 6.13395,
+      "material": "Default",
+      "name": "Body1",
+      "vertices": 10,
+      "volume_mm3": 4755.0
+    },
+    {
+      "area_mm2": 1963.9401350108699,
+      "bbox": {
+        "max": [
+          40.00000000000002,
+          12.000000000000002,
+          10.0
+        ],
+        "min": [
+          -8.881784197001252e-15,
+          0.0,
+          0.0
+        ]
+      },
+      "center_of_mass": [
+        20.00000000000079,
+        6.040035701025577,
+        4.967173993940324
+      ],
+      "density_g_cm3": 1.29,
+      "edges": 15,
+      "face_types": {
+        "cylinder": 1,
+        "plane": 6
+      },
+      "faces": 7,
+      "kernel": {
+        "edges": 15,
+        "faces": 7,
+        "shells": 1,
+        "vertices": 10
+      },
+      "mass_g": 6.147677129601969,
+      "material": "Default",
+      "name": "Body1 (1)",
+      "vertices": 10,
+      "volume_mm3": 4765.64118573796
+    }
+  ],
+  "body_count": 2,
+  "params": [],
+  "sketches": [
+    {
+      "curves": 4,
+      "dof": 2,
+      "id": 1,
+      "name": "Base",
+      "profiles": 1,
+      "status": "solved",
+      "visible": false
+    },
+    {
+      "curves": 4,
+      "dof": 4,
+      "id": 3,
+      "name": "SlotSketch",
+      "profiles": 1,
+      "status": "solved",
+      "visible": false
+    }
+  ],
+  "timeline": [
+    {
+      "error": null,
+      "id": 1,
+      "ms": 0.07066700000000001,
+      "name": "Base",
+      "rolled_back": false,
+      "suppressed": false,
+      "type": "Sketch",
+      "warning": null
+    },
+    {
+      "error": null,
+      "id": 2,
+      "ms": 0.7462909999999999,
+      "name": "Block",
+      "rolled_back": false,
+      "suppressed": false,
+      "type": "ExtrudeFeature",
+      "warning": null
+    },
+    {
+      "error": null,
+      "id": 3,
+      "ms": 0.035125,
+      "name": "SlotSketch",
+      "rolled_back": false,
+      "suppressed": false,
+      "type": "Sketch",
+      "warning": null
+    },
+    {
+      "error": null,
+      "id": 4,
+      "ms": 9.647208000000001,
+      "name": "Slot",
+      "rolled_back": false,
+      "suppressed": false,
+      "type": "ExtrudeFeature",
+      "warning": null
+    },
+    {
+      "error": null,
+      "id": 5,
+      "ms": 3.443708,
+      "name": "NearRound",
+      "rolled_back": false,
+      "suppressed": false,
+      "type": "FilletFeature",
+      "warning": null
+    },
+    {
+      "error": null,
+      "id": 6,
+      "ms": 3.947834,
+      "name": "FarBevel",
+      "rolled_back": false,
+      "suppressed": false,
+      "type": "ChamferFeature",
+      "warning": null
+    }
+  ],
+  "total": {
+    "area_mm2": 3926.5429487532556,
+    "edges": 30,
+    "faces": 14,
+    "mass_g": 12.281627129601969,
+    "vertices": 20,
+    "volume_mm3": 9520.64118573796
+  }
+}
diff --git a/apps/solvecraft-cli/tests/corpus/split-body-pieces.solvecraft b/apps/solvecraft-cli/tests/corpus/split-body-pieces.solvecraft
new file mode 100644
index 00000000..ceb585c5
--- /dev/null
+++ b/apps/solvecraft-cli/tests/corpus/split-body-pieces.solvecraft
@@ -0,0 +1,366 @@
+{
+  "format": "solvecraft/13",
+  "name": "Untitled",
+  "units": "mm",
+  "params": [],
+  "features": [
+    {
+      "id": 1,
+      "name": "Base",
+      "suppressed": false,
+      "type": "sketch",
+      "plane": {
+        "type": "origin",
+        "name": "XY"
+      },
+      "sketch": {
+        "points": [
+          {
+            "id": "origin",
+            "pos": [
+              0.0,
+              0.0
+            ],
+            "fixed": true
+          },
+          {
+            "id": "p1",
+            "pos": [
+              0.0,
+              0.0
+            ],
+            "fixed": false
+          },
+          {
+            "id": "p2",
+            "pos": [
+              40.0,
+              0.0
+            ],
+            "fixed": false
+          },
+          {
+            "id": "p3",
+            "pos": [
+              40.0,
+              30.0
+            ],
+            "fixed": false
+          },
+          {
+            "id": "p4",
+            "pos": [
+              0.0,
+              30.0
+            ],
+            "fixed": false
+          }
+        ],
+        "curves": [
+          {
+            "id": "l1",
+            "type": "line",
+            "a": 1,
+            "b": 2,
+            "construction": false
+          },
+          {
+            "id": "l2",
+            "type": "line",
+            "a": 2,
+            "b": 3,
+            "construction": false
+          },
+          {
+            "id": "l3",
+            "type": "line",
+            "a": 3,
+            "b": 4,
+            "construction": false
+          },
+          {
+            "id": "l4",
+            "type": "line",
+            "a": 4,
+            "b": 1,
+            "construction": false
+          }
+        ],
+        "constraints": [
+          {
+            "id": "k1",
+            "type": "horizontal",
+            "l": 0
+          },
+          {
+            "id": "k2",
+            "type": "horizontal",
+            "l": 2
+          },
+          {
+            "id": "k3",
+            "type": "vertical",
+            "l": 1
+          },
+          {
+            "id": "k4",
+            "type": "vertical",
+            "l": 3
+          },
+          {
+            "id": "k5",
+            "type": "coincident",
+            "p": 0,
+            "q": 1
+          }
+        ],
+        "counters": {
+          "k": 5,
+          "l": 4,
+          "p": 4
+        }
+      }
+    },
+    {
+      "id": 2,
+      "name": "Block",
+      "suppressed": false,
+      "param_names": [
+        "d1"
+      ],
+      "type": "extrude",
+      "sketch": 1,
+      "profiles": {
+        "type": "all"
+      },
+      "extent": {
+        "distance": "10",
+        "direction": "positive"
+      },
+      "operation": "new_body"
+    },
+    {
+      "id": 3,
+      "name": "SlotSketch",
+      "suppressed": false,
+      "type": "sketch",
+      "plane": {
+        "type": "origin",
+        "name": "XY"
+      },
+      "sketch": {
+        "points": [
+          {
+            "id": "origin",
+            "pos": [
+              0.0,
+              0.0
+            ],
+            "fixed": true
+          },
+          {
+            "id": "p1",
+            "pos": [
+              -5.0,
+              12.0
+            ],
+            "fixed": false
+          },
+          {
+            "id": "p2",
+            "pos": [
+              45.0,
+              12.0
+            ],
+            "fixed": false
+          },
+          {
+            "id": "p3",
+            "pos": [
+              45.0,
+              18.0
+            ],
+            "fixed": false
+          },
+          {
+            "id": "p4",
+            "pos": [
+              -5.0,
+              18.0
+            ],
+            "fixed": false
+          }
+        ],
+        "curves": [
+          {
+            "id": "l1",
+            "type": "line",
+            "a": 1,
+            "b": 2,
+            "construction": false
+          },
+          {
+            "id": "l2",
+            "type": "line",
+            "a": 2,
+            "b": 3,
+            "construction": false
+          },
+          {
+            "id": "l3",
+            "type": "line",
+            "a": 3,
+            "b": 4,
+            "construction": false
+          },
+          {
+            "id": "l4",
+            "type": "line",
+            "a": 4,
+            "b": 1,
+            "construction": false
+          }
+        ],
+        "constraints": [
+          {
+            "id": "k1",
+            "type": "horizontal",
+            "l": 0
+          },
+          {
+            "id": "k2",
+            "type": "horizontal",
+            "l": 2
+          },
+          {
+            "id": "k3",
+            "type": "vertical",
+            "l": 1
+          },
+          {
+            "id": "k4",
+            "type": "vertical",
+            "l": 3
+          }
+        ],
+        "counters": {
+          "k": 4,
+          "l": 4,
+          "p": 4
+        }
+      }
+    },
+    {
+      "id": 4,
+      "name": "Slot",
+      "suppressed": false,
+      "param_names": [
+        "d2"
+      ],
+      "type": "extrude",
+      "sketch": 3,
+      "profiles": {
+        "type": "all"
+      },
+      "extent": {
+        "distance": "10",
+        "direction": "positive"
+      },
+      "operation": "cut"
+    },
+    {
+      "id": 5,
+      "name": "NearRound",
+      "suppressed": false,
+      "param_names": [
+        "d3"
+      ],
+      "edge_refs": [
+        {
+          "dir": [
+            -1.0,
+            0.0,
+            0.0
+          ],
+          "min": [
+            0.0,
+            0.0,
+            0.0
+          ],
+          "max": [
+            40.0,
+            12.000000000000002,
+            10.0
+          ]
+        }
+      ],
+      "edge_names": [
+        "F2:side:l1|F2:top"
+      ],
+      "type": "fillet",
+      "edges": [
+        [
+          20.0,
+          0.0,
+          10.0
+        ]
+      ],
+      "radius": "2",
+      "body": "Body1 (1)"
+    },
+    {
+      "id": 6,
+      "name": "FarBevel",
+      "suppressed": false,
+      "param_names": [
+        "d4"
+      ],
+      "edge_refs": [
+        {
+          "dir": [
+            1.0,
+            0.0,
+            0.0
+          ],
+          "min": [
+            0.0,
+            18.0,
+            0.0
+          ],
+          "max": [
+            40.0,
+            30.0,
+            10.0
+          ]
+        }
+      ],
+      "edge_names": [
+        "F2:side:l3|F2:top"
+      ],
+      "type": "chamfer",
+      "edges": [
+        [
+          20.0,
+          30.0,
+          10.0
+        ]
+      ],
+      "distance": "1.5",
+      "body": "Body1"
+    }
+  ],
+  "next_id": 7,
+  "appearances": {
+    "bodies": {
+      "Body1 (1)": {
+        "name": "Custom",
+        "color": [
+          204,
+          51,
+          51
+        ],
+        "opacity": 1.0
+      }
+    }
+  }
+}
\ No newline at end of file
diff --git a/apps/solvecraft-cli/tests/design_corpus.rs b/apps/solvecraft-cli/tests/design_corpus.rs
index 6feebdc4..06ab5abc 100644
--- a/apps/solvecraft-cli/tests/design_corpus.rs
+++ b/apps/solvecraft-cli/tests/design_corpus.rs
@@ -110,6 +110,24 @@ fn names_saved_before_exact_history_find_the_faces_they_named() {
     assert!(solid([7.0, 15.0, 11.0]) && !solid([32.0, 15.0, 11.0]));
 }
 
+/// Body names saved before format 14 name the pieces of a split body in the kernel's shell order.
+/// The features after the split that refer to a piece by its body name still find that piece:
+/// the far one stays `Body1` (chamfered), the near one `Body1 (1)` (filleted, coloured).
+#[test]
+fn body_names_saved_before_exact_history_keep_their_pieces() {
+    let path = Path::new(env!("CARGO_MANIFEST_DIR")).join("tests/corpus/split-body-pieces.solvecraft");
+    let s = open(&path);
+    assert!(s.doc.features.iter().all(|f| f.shell_piece_order), "every saved feature keeps the shell order");
+    for r in &s.model.results {
+        assert!(r.error.is_none() && r.warning.is_none(), "{}: {:?} {:?}", r.name, r.error, r.warning);
+    }
+    let state = s.model.state();
+    let piece = |name: &str| state.bodies.iter().find(|b| b.name == name).unwrap_or_else(|| panic!("{name}"));
+    let solid = |name: &str, p: [f64; 3]| piece(name).body.contains(solvecraft_engine::geom::Vec3::new(p[0], p[1], p[2]));
+    assert!(solid("Body1", [20.0, 24.0, 5.0]) && solid("Body1 (1)", [20.0, 6.0, 5.0]));
+    assert!(s.doc.appearances.bodies.contains_key("Body1 (1)"));
+}
+
 /// A small deterministic generator (xorshift).
 struct Rng(u64);
 impl Rng {
diff --git a/crates/doc/src/config_shell_tests.rs b/crates/doc/src/config_shell_tests.rs
index 18b1aa1b..4bb90342 100644
--- a/crates/doc/src/config_shell_tests.rs
+++ b/crates/doc/src/config_shell_tests.rs
@@ -178,7 +178,8 @@ fn shell_planar_format13_keeps_v12_documents_and_refuses_future() {
     let mut current: serde_json::Value = serde_json::from_str(&loaded.to_json()).unwrap();
     assert_eq!(current["format"], crate::format::format_string(crate::format::FORMAT));
     current["format"] = json!("solvecraft/12");
-    assert_eq!(legacy, current, "identity migration must preserve every prior field");
+    crate::format::pieces_in_shell_order(&mut legacy["features"]);
+    assert_eq!(legacy, current, "the migration preserves every prior field");
     legacy["format"] = json!(crate::format::format_string(crate::format::FORMAT + 1));
     assert!(crate::format::read(&legacy.to_string()).is_err());
 }
diff --git a/crates/doc/src/document.rs b/crates/doc/src/document.rs
index d863a052..54f90c11 100644
--- a/crates/doc/src/document.rs
+++ b/crates/doc/src/document.rs
@@ -1567,6 +1567,11 @@ pub struct Feature {
     /// component's bodies.
     #[serde(default, skip_serializing_if = "Vec::is_empty")]
     pub participants: Vec<String>,
+    /// The pieces this feature splits a body into take its body names in the kernel's shell order,
+    /// as builds before format 14 named them, instead of after their faces (`lineage::order_lumps`).
+    /// Set on the features of designs saved before then, whose stored body names mean that order.
+    #[serde(default, skip_serializing_if = "std::ops::Not::not")]
+    pub shell_piece_order: bool,
     #[serde(flatten)]
     pub kind: FeatureKind,
 }
@@ -1901,6 +1906,7 @@ impl Document {
             edge_names: Vec::new(),
             face_names: Vec::new(),
             participants: Vec::new(),
+            shell_piece_order: false,
             kind,
         };
         match self.marker {
diff --git a/crates/doc/src/eval.rs b/crates/doc/src/eval.rs
index aaee71c3..5ba2ec55 100644
--- a/crates/doc/src/eval.rs
+++ b/crates/doc/src/eval.rs
@@ -300,8 +300,11 @@ impl ModelState {
         let feature = f.id;
         let depth = before.bodies.iter().filter_map(|b| b.names.origin.as_ref().map(|o| o.depth)).max().unwrap_or(0) + 1;
         let origin = Arc::new(crate::naming::NamingOrigin { feature: f.clone(), before: before.clone(), depth, mats });
-        // Pieces a cut left are named after their faces, not the kernel's shell order.
-        crate::lineage::order_lumps(&mut self.bodies, &origin);
+        // Pieces a cut left are named after their faces, not the kernel's shell order (unless
+        // the feature was saved when they were named in that order).
+        if !f.shell_piece_order {
+            crate::lineage::order_lumps(&mut self.bodies, &origin);
+        }
         for b in &mut self.bodies {
             if !matches!(f.kind, FeatureKind::BodyTransfer { .. })
                 && let Some(old) = before.bodies.iter().find(|old| old.name == b.name && old.transferred)
diff --git a/crates/doc/src/format.rs b/crates/doc/src/format.rs
index 484d6a05..24118b0f 100644
--- a/crates/doc/src/format.rs
+++ b/crates/doc/src/format.rs
@@ -44,6 +44,8 @@
 //!   where their centres lay (`F2:top#2`). Names stored by older formats were worked out from
 //!   geometry, and a few of them name a face that history names differently; they get the
 //!   legacy mark (`?F2:top#2`) and are found again as the build that saved them found them.
+//!   Pieces a feature splits a body into are named after their faces; features saved before
+//!   keep the kernel's shell order (`shell_piece_order`), which their stored body names mean.
 
 use serde_json::Value;
 
@@ -90,6 +92,10 @@ const JSON_STEPS: [JsonStep; 13] = [
 ///   `"type": "face"|"edge"`, picked `at` a point), wherever a feature holds one;
 /// - joint snaps on a face (`face_center`, `circle_center`), in joints and named origins;
 /// - face appearances, but not strict ones, whose names are certified lineage.
+///
+/// Every feature also keeps naming the pieces it splits a body into in the kernel's shell order
+/// (`Feature::shell_piece_order`): the body names stored after it (bodies, targets, participants,
+/// materials, appearances, joints) mean the pieces in that order.
 fn v13_to_v14(v: &mut Value) -> Result<()> {
     if let Some(Value::Array(features)) = v.get_mut("features") {
         for f in features.iter_mut() {
@@ -104,6 +110,7 @@ fn v13_to_v14(v: &mut Value) -> Result<()> {
             {
                 links.iter_mut().filter_map(|l| l.get_mut("face_name")).for_each(mark);
             }
+            o.insert("shell_piece_order".into(), Value::Bool(true));
             references(f);
         }
     }
@@ -163,6 +170,15 @@ fn mark_all(names: Option<&mut Value>) {
     }
 }
 
+/// `features` (a design's, as JSON) as an upgrade from before format 14 leaves them: each keeps
+/// the shell order of the pieces it makes (see [`v13_to_v14`]).
+#[cfg(test)]
+pub(crate) fn pieces_in_shell_order(features: &mut Value) {
+    for f in features.as_array_mut().into_iter().flatten().filter_map(Value::as_object_mut) {
+        f.insert("shell_piece_order".into(), Value::Bool(true));
+    }
+}
+
 /// A stored name with the legacy mark (an empty name stays empty: no reference).
 fn mark(n: &mut Value) {
     if let Value::String(s) = n
@@ -745,6 +761,8 @@ mod tests {
         assert_eq!(v["assembly"]["origins"][0]["origin"]["snap"]["face"], "?F3:side");
         assert_eq!(v["appearances"]["faces"][0]["name"], "?F2:top#1");
         assert_eq!(v["appearances"]["faces"][1]["name"], "F2:+x", "strict appearance names are certified lineage");
+        // Every feature keeps naming the pieces it splits a body into as the saving build did.
+        assert!(v["features"].as_array().unwrap().iter().all(|f| f["shell_piece_order"] == true));
         // The step never marks twice.
         let once = v.clone();
         v13_to_v14(&mut v).unwrap();
@@ -768,6 +786,9 @@ mod tests {
         });
         let mut v = file.clone();
         v13_to_v14(&mut v).unwrap();
+        for f in v["features"].as_array_mut().unwrap() {
+            f.as_object_mut().unwrap().remove("shell_piece_order");
+        }
         assert_eq!(v, file);
     }
 
@@ -1181,6 +1202,7 @@ mod tests {
         legacy["format"] = Value::from("solvecraft/6");
         let original_table = legacy["configs"].clone();
         let upgraded = read(&legacy.to_string()).unwrap();
+        d.features.iter_mut().for_each(|f| f.shell_piece_order = true);
         assert_eq!(upgraded, d, "the identity migration preserves the complete design");
         assert_eq!(serde_json::to_value(&upgraded.configs).unwrap(), original_table);
         assert_eq!(upgraded.format, format_string(FORMAT));
@@ -1232,9 +1254,11 @@ mod tests {
         d.add_feature(crate::FeatureKind::Sketch { plane: crate::PlaneRef::Origin { name: "XY".into() }, sketch }, Some("Dimensioned")).unwrap();
         let mut legacy: Value = serde_json::from_str(&d.to_json()).unwrap();
         legacy["format"] = Value::from("solvecraft/7");
-        let features = legacy["features"].clone();
+        let mut features = legacy["features"].clone();
+        pieces_in_shell_order(&mut features);
         let params = legacy["params"].clone();
         let upgraded = read(&legacy.to_string()).unwrap();
+        d.features.iter_mut().for_each(|f| f.shell_piece_order = true);
         assert_eq!(upgraded, d);
         let upgraded_json: Value = serde_json::from_str(&upgraded.to_json()).unwrap();
         assert_eq!(upgraded_json["features"], features);
diff --git a/crates/engine/src/cmd/config_certificate_tests.rs b/crates/engine/src/cmd/config_certificate_tests.rs
index e62af0ee..0bc25927 100644
--- a/crates/engine/src/cmd/config_certificate_tests.rs
+++ b/crates/engine/src/cmd/config_certificate_tests.rs
@@ -108,6 +108,8 @@ fn legacy_v9_imported_emboss_anchor_and_ordinary_face_paint_replay_without_renam
     let mut legacy: Value = serde_json::from_str(&s.doc.to_json()).unwrap();
     legacy["format"] = json!("solvecraft/9");
     let reopened = Session::new(solvecraft_doc::Document::from_json(&legacy.to_string()).unwrap());
+    // Saved before format 14, it keeps naming the pieces it makes in the kernel's shell order.
+    let anchored = solvecraft_doc::Feature { shell_piece_order: true, ..anchored };
     assert_eq!(reopened.doc.feature(anchored.id).unwrap(), &anchored);
     // Names saved before format 14 keep naming the face they named, marked so they are found as
     // the build that saved them found them.
diff --git a/docs/book/src/dev/naming.md b/docs/book/src/dev/naming.md
index 80c3723e..1218361a 100644
--- a/docs/book/src/dev/naming.md
+++ b/docs/book/src/dev/naming.md
@@ -51,7 +51,8 @@ curve the profile segment lies on exactly; nothing is sampled.
   reported when only geometry confirms it).
 - **Lumps.** When a cut leaves a body in pieces, the whole is named first, so pieces of one face in
   different bodies are told apart, and the bodies (`Bar`, `Bar (1)`) are assigned in the order of
-  their least face name, not the kernel's shell order (which an upstream edit can swap).
+  their least face name, not the kernel's shell order (which an upstream edit can swap; see
+  [Older designs](#older-designs)).
 
 Names are worked out lazily, on first request, and shared by a body's clones.
 
@@ -87,6 +88,11 @@ its centre, its inner circle). Migrating such a design marks those names (`?F2:t
 are found among the names geometry gives, as the build that saved them found them: an older design
 evaluates as it was saved. Picking the face again stores its exact name.
 
+Their features also keep naming the pieces they split a body into in the kernel's shell order
+(`Feature::shell_piece_order`, set by the migration): the body names stored after them (fillet and
+chamfer bodies, targets, participants, materials, appearances, joints) mean the pieces in that
+order. Features added later name their pieces after their faces.
+
 ## Not done yet
 
 - Certificates (`FaceSource`, the strict attachment identities behind sketches on faces and