diff --git a/Cargo.lock b/Cargo.lock
index 6aef22802..661be0bc6 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -4205,7 +4205,7 @@ dependencies = [
 [[package]]
 name = "opencadcodec"
 version = "0.6.0"
-source = "git+https://github.com/HakanSeven12/opencadcodec.git?rev=ab2eecd#ab2eecdbffc31120b5ad6d899f6fc67cf21ede39"
+source = "git+https://github.com/HakanSeven12/opencadcodec.git?rev=c9ffcac#c9ffcac5ecdc7a504cc4a7e3ecb52ac9d587c8bf"
 dependencies = [
  "anyhow",
  "bitflags 2.13.1",
@@ -4228,7 +4228,7 @@ dependencies = [
 [[package]]
 name = "opencadgraph"
 version = "0.1.0"
-source = "git+https://github.com/HakanSeven12/opencadgraph.git?rev=194e619#194e6192c9eca5c916371e7434b9fde18911aa6a"
+source = "git+https://github.com/HakanSeven12/opencadgraph.git?rev=7f6aae7#7f6aae7aff6b7de87cc1dcdb38a06c3e64ae1922"
 dependencies = [
  "opencadkernel",
  "serde_json",
@@ -4237,7 +4237,7 @@ dependencies = [
 [[package]]
 name = "opencadkernel"
 version = "0.1.0"
-source = "git+https://github.com/HakanSeven12/opencadkernel.git?rev=bf44e68#bf44e6856f2582eb5df5038650b6a6910eb9dac5"
+source = "git+https://github.com/HakanSeven12/opencadkernel.git?rev=99b6b48#99b6b4890704d300596ba502b5a1c8ec1eefa954"
 dependencies = [
  "cavalier_contours",
  "opencadcodec",
@@ -4248,7 +4248,7 @@ dependencies = [
 [[package]]
 name = "opencadkernel-constraints"
 version = "0.1.0"
-source = "git+https://github.com/HakanSeven12/opencadkernel.git?rev=bf44e68#bf44e6856f2582eb5df5038650b6a6910eb9dac5"
+source = "git+https://github.com/HakanSeven12/opencadkernel.git?rev=99b6b48#99b6b4890704d300596ba502b5a1c8ec1eefa954"
 dependencies = [
  "nalgebra",
 ]
diff --git a/Cargo.toml b/Cargo.toml
index 64187a804..c9480bb41 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -34,10 +34,10 @@ rfd = "0.17"
 clap = { version = "4", features = ["derive", "string"] }
 env_logger = "0.11"
 log = "0.4"
-codec = { package = "opencadcodec", git = "https://github.com/HakanSeven12/opencadcodec.git", rev = "ab2eecd", features = ["serde"] }
-kernel = { package = "opencadkernel", git = "https://github.com/HakanSeven12/opencadkernel.git", rev = "bf44e68", features = ["acis", "offset"] }
-kernel-constraints = { package = "opencadkernel-constraints", git = "https://github.com/HakanSeven12/opencadkernel.git", rev = "bf44e68" }
-graph = { package = "opencadgraph", git = "https://github.com/HakanSeven12/opencadgraph.git", rev = "194e619" }
+codec = { package = "opencadcodec", git = "https://github.com/HakanSeven12/opencadcodec.git", rev = "c9ffcac", features = ["serde"] }
+kernel = { package = "opencadkernel", git = "https://github.com/HakanSeven12/opencadkernel.git", rev = "99b6b48", features = ["acis", "offset"] }
+kernel-constraints = { package = "opencadkernel-constraints", git = "https://github.com/HakanSeven12/opencadkernel.git", rev = "99b6b48" }
+graph = { package = "opencadgraph", git = "https://github.com/HakanSeven12/opencadgraph.git", rev = "7f6aae7" }
 dwg-thumbnailer = { path = "crates/dwg-thumbnailer" }
 flate2 = "1"
 image = { version = "0.25", default-features = false, features = ["png", "jpeg", "bmp", "tiff"] }
diff --git a/crates/ocs_plugin_api/Cargo.toml b/crates/ocs_plugin_api/Cargo.toml
index 85f91b710..2ff186185 100644
--- a/crates/ocs_plugin_api/Cargo.toml
+++ b/crates/ocs_plugin_api/Cargo.toml
@@ -15,7 +15,7 @@ serde_json = { version = "1", optional = true }
 # Pulled in only by the `host` feature, which adds the `opencadcodec`-typed
 # `HostApi` runtime surface. The default crate stays dependency-free so engine
 # crates and external tooling can depend on the manifest/ribbon contract cheaply.
-codec = { package = "opencadcodec", git = "https://github.com/HakanSeven12/opencadcodec.git", rev = "ab2eecd", optional = true, features = ["serde"] }
+codec = { package = "opencadcodec", git = "https://github.com/HakanSeven12/opencadcodec.git", rev = "c9ffcac", optional = true, features = ["serde"] }
 
 # Runtime IPC and serialization (host feature only).
 interprocess = { version = "2", optional = true }
@@ -39,7 +39,7 @@ serde_json = "1"
 serde = { version = "1", features = ["derive"] }
 cargo-lock = "11"
 # opencadcodec is scanned at build time to generate the embedded type registry.
-codec = { package = "opencadcodec", git = "https://github.com/HakanSeven12/opencadcodec.git", rev = "ab2eecd", features = ["serde"] }
+codec = { package = "opencadcodec", git = "https://github.com/HakanSeven12/opencadcodec.git", rev = "c9ffcac", features = ["serde"] }
 
 [dev-dependencies]
 serde_json = "1"
diff --git a/crates/ocs_web_worker/Cargo.toml b/crates/ocs_web_worker/Cargo.toml
index 9a406230b..00e7bbd79 100644
--- a/crates/ocs_web_worker/Cargo.toml
+++ b/crates/ocs_web_worker/Cargo.toml
@@ -8,7 +8,7 @@ publish = false
 crate-type = ["cdylib"]
 
 [dependencies]
-codec = { package = "opencadcodec", git = "https://github.com/HakanSeven12/opencadcodec.git", rev = "ab2eecd", features = ["serde"] }
+codec = { package = "opencadcodec", git = "https://github.com/HakanSeven12/opencadcodec.git", rev = "c9ffcac", features = ["serde"] }
 bincode = "1.3"
 serde = { version = "1", features = ["derive"] }
 console_error_panic_hook = "0.1"
diff --git a/plugins/opencad-python/Cargo.lock b/plugins/opencad-python/Cargo.lock
index 76d4cfd36..308d68303 100644
--- a/plugins/opencad-python/Cargo.lock
+++ b/plugins/opencad-python/Cargo.lock
@@ -1264,7 +1264,7 @@ dependencies = [
 [[package]]
 name = "opencadcodec"
 version = "0.6.0"
-source = "git+https://github.com/HakanSeven12/opencadcodec.git?rev=ab2eecd#ab2eecdbffc31120b5ad6d899f6fc67cf21ede39"
+source = "git+https://github.com/HakanSeven12/opencadcodec.git?rev=c9ffcac#c9ffcac5ecdc7a504cc4a7e3ecb52ac9d587c8bf"
 dependencies = [
  "anyhow",
  "bitflags",
diff --git a/src/scene/model/sweep_command_model.rs b/src/scene/model/sweep_command_model.rs
index 7913e22a6..486156ec3 100644
--- a/src/scene/model/sweep_command_model.rs
+++ b/src/scene/model/sweep_command_model.rs
@@ -167,7 +167,11 @@ pub fn sweep_selection_options(profiles: &[EntityType], mut options: SweepOption
     }
     // Spatial profiles keep their own anchor.
     let profiles = profiles.iter().filter(|profile| spatial_profile(profile).is_none()).collect::<Vec<_>>();
-    if profiles.is_empty() {
+    // A single profile takes its base from the path it is swept along
+    // (`sweep_record`).
+    // ponytail: several profiles share the group anchor even when the path
+    // starts inside one of them; the reference rule for that case is unmeasured.
+    if profiles.len() < 2 {
         return Some(options);
     }
     let geometry = profiles.iter().map(|profile| {
@@ -229,10 +233,10 @@ pub fn sweep_record(profile: &EntityType, path: &EntityType, options: SweepOptio
         return Some(record);
     }
     let (sweep_entity, sweep_entity_transform) = embedded_sweep_profile(profile)?;
-    let (plane, wires, _) = kernel::acis::sweep_profile_geometry(&sweep_entity, sweep_entity_transform).ok()?;
+    kernel::acis::sweep_profile_geometry(&sweep_entity, sweep_entity_transform).ok()?;
     let base_point = match options.base_point {
         Some(point) => point.to_array(),
-        None => kernel::brep::sweep_profile_base(plane, &wires)?,
+        None => kernel::acis::sweep_default_base(&sweep_entity, sweep_entity_transform, &embedded_sweep_path(path)?).ok()?,
     };
     let mut base = SolidHistoryNodeBase::new(1);
     base.transform = glam::DMat4::IDENTITY.to_cols_array();