diff --git a/Cargo.lock b/Cargo.lock
index 6295effe8..26659a805 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -4201,7 +4201,7 @@ dependencies = [
 [[package]]
 name = "opencadcodec"
 version = "0.5.5"
-source = "git+https://github.com/HakanSeven12/opencadcodec.git?rev=d6d534f#d6d534fcfec5823e47ef5630668d8e16d62c1641"
+source = "git+https://github.com/HakanSeven12/opencadcodec.git?rev=7c20aa7#7c20aa7fad405845c5bd5cdcc2a232cdc2a4687d"
 dependencies = [
  "ahash 0.8.12",
  "anyhow",
@@ -4224,7 +4224,7 @@ dependencies = [
 [[package]]
 name = "opencadgraph"
 version = "0.1.0"
-source = "git+https://github.com/HakanSeven12/opencadgraph.git?rev=5c9b004#5c9b004a2fd10b9eb62b8d54ce443120ee417a95"
+source = "git+https://github.com/HakanSeven12/opencadgraph.git?rev=1543a5a#1543a5aeb0b871a2f23a3b55117c7f5af1e1d229"
 dependencies = [
  "opencadkernel",
  "serde_json",
@@ -4233,7 +4233,7 @@ dependencies = [
 [[package]]
 name = "opencadkernel"
 version = "0.1.0"
-source = "git+https://github.com/HakanSeven12/opencadkernel.git?rev=5d9e921#5d9e92104830444ca48ac7c5a8cdcfa24c21786b"
+source = "git+https://github.com/HakanSeven12/opencadkernel.git?rev=d71a828#d71a8284f0388025e07f219c7b8f6bb86e7188ec"
 dependencies = [
  "cavalier_contours",
  "opencadcodec",
@@ -4244,7 +4244,7 @@ dependencies = [
 [[package]]
 name = "opencadkernel-constraints"
 version = "0.1.0"
-source = "git+https://github.com/HakanSeven12/opencadkernel.git?rev=5d9e921#5d9e92104830444ca48ac7c5a8cdcfa24c21786b"
+source = "git+https://github.com/HakanSeven12/opencadkernel.git?rev=d71a828#d71a8284f0388025e07f219c7b8f6bb86e7188ec"
 dependencies = [
  "nalgebra",
 ]
diff --git a/Cargo.toml b/Cargo.toml
index 9d4b1f7a7..7ad93dc7e 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -33,10 +33,10 @@ 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 = "d6d534f", features = ["serde"] }
-kernel = { package = "opencadkernel", git = "https://github.com/HakanSeven12/opencadkernel.git", rev = "5d9e921", features = ["acis", "offset"] }
-kernel-constraints = { package = "opencadkernel-constraints", git = "https://github.com/HakanSeven12/opencadkernel.git", rev = "5d9e921" }
-graph = { package = "opencadgraph", git = "https://github.com/HakanSeven12/opencadgraph.git", rev = "5c9b004" }
+codec = { package = "opencadcodec", git = "https://github.com/HakanSeven12/opencadcodec.git", rev = "7c20aa7", features = ["serde"] }
+kernel = { package = "opencadkernel", git = "https://github.com/HakanSeven12/opencadkernel.git", rev = "d71a828", features = ["acis", "offset"] }
+kernel-constraints = { package = "opencadkernel-constraints", git = "https://github.com/HakanSeven12/opencadkernel.git", rev = "d71a828" }
+graph = { package = "opencadgraph", git = "https://github.com/HakanSeven12/opencadgraph.git", rev = "1543a5a" }
 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 022c95c09..91efdc937 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 = "d6d534f", optional = true, features = ["serde"] }
+codec = { package = "opencadcodec", git = "https://github.com/HakanSeven12/opencadcodec.git", rev = "7c20aa7", 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 = "d6d534f", features = ["serde"] }
+codec = { package = "opencadcodec", git = "https://github.com/HakanSeven12/opencadcodec.git", rev = "7c20aa7", features = ["serde"] }
 
 [dev-dependencies]
 serde_json = "1"
diff --git a/crates/ocs_web_worker/Cargo.toml b/crates/ocs_web_worker/Cargo.toml
index fd592806b..229386607 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 = "d6d534f", features = ["serde"] }
+codec = { package = "opencadcodec", git = "https://github.com/HakanSeven12/opencadcodec.git", rev = "7c20aa7", 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 dcca42de7..039e59eaf 100644
--- a/plugins/opencad-python/Cargo.lock
+++ b/plugins/opencad-python/Cargo.lock
@@ -1265,7 +1265,7 @@ dependencies = [
 [[package]]
 name = "opencadcodec"
 version = "0.5.5"
-source = "git+https://github.com/HakanSeven12/opencadcodec.git?rev=d6d534f#d6d534fcfec5823e47ef5630668d8e16d62c1641"
+source = "git+https://github.com/HakanSeven12/opencadcodec.git?rev=7c20aa7#7c20aa7fad405845c5bd5cdcc2a232cdc2a4687d"
 dependencies = [
  "ahash 0.8.12",
  "anyhow",
diff --git a/src/scene/mod.rs b/src/scene/mod.rs
index 3e3264fe5..6c1f1a012 100644
--- a/src/scene/mod.rs
+++ b/src/scene/mod.rs
@@ -8108,6 +8108,33 @@ impl Scene {
             .unwrap_or(false)
     }
 
+    /// Handles hidden inside content viewport `vp`: its VP-frozen layers plus
+    /// model-space references bound to another viewport (Inventor drawing
+    /// views overlap in model space; each is drawn only in its own viewport).
+    /// Entity and layer handles never collide, so both ride the same set and
+    /// its cache signature.
+    pub(super) fn viewport_hidden_handles(&self, vp: Handle) -> HashSet<Handle> {
+        let mut hidden: HashSet<Handle> = match self.document.get_entity(vp) {
+            Some(EntityType::Viewport(v)) => v.frozen_layers.iter().copied().collect(),
+            _ => HashSet::default(),
+        };
+        // ponytail: full entity scan per call, gated to drawings declaring the
+        // class; memoize per geometry epoch if large Inventor sheets show up.
+        if self.document.classes.get_by_name("ACIDBLOCKREFERENCE").is_some() {
+            let model = self.model_space_block_handle();
+            hidden.extend(self.document.entities().filter_map(|e| match e {
+                EntityType::Insert(i)
+                    if i.common.owner_handle == model
+                        && i.view_rep_handle.is_some_and(|bound| bound != vp) =>
+                {
+                    Some(i.common.handle)
+                }
+                _ => None,
+            }));
+        }
+        hidden
+    }
+
     /// True when `layer`'s handle is in a content viewport's per-viewport
     /// frozen-layer set (VP freeze). Mirrors the wire path's test in
     /// [`Scene::resident_entity_visible`] so fills / images / meshes hide on the
@@ -10199,6 +10226,9 @@ impl Scene {
         }
         if let Some(frozen) = frozen_layers {
             if !frozen.is_empty() {
+                if frozen.contains(&c.handle) {
+                    return false;
+                }
                 if let Some(lh) = layer.map(|l| l.handle) {
                     if frozen.contains(&lh) {
                         return false;
diff --git a/src/scene/paper.rs b/src/scene/paper.rs
index 58ccd48af..1ad157080 100644
--- a/src/scene/paper.rs
+++ b/src/scene/paper.rs
@@ -828,13 +828,7 @@ impl Scene {
         // wheel tick whenever the drawing contained one annotative object.
         // Explicit viewport annotation-scale changes still rebuild the resident
         // set; PSLTSCALE is a viewport GPU uniform.
-        let frozen = match self.document.get_entity(vp_handle) {
-            Some(EntityType::Viewport(vp)) => {
-                let f: HSet<Handle> = vp.frozen_layers.iter().cloned().collect();
-                f
-            }
-            _ => HSet::default(),
-        };
+        let frozen: HSet<Handle> = self.viewport_hidden_handles(vp_handle);
 
         let scale_handle = self.viewport_scale_handle(vp_handle);
         self.resident_wires_for(
diff --git a/src/scene/render_graph.rs b/src/scene/render_graph.rs
index 5e98f2ee0..dcb8a0199 100644
--- a/src/scene/render_graph.rs
+++ b/src/scene/render_graph.rs
@@ -612,7 +612,8 @@ impl<'a> RenderSceneGraph<'a> {
             return false;
         }
         if self.frozen_layers.is_some_and(|frozen| {
-            layer.is_some_and(|layer| frozen.contains(&layer.handle))
+            frozen.contains(&common.handle)
+                || layer.is_some_and(|layer| frozen.contains(&layer.handle))
         }) {
             return false;
         }
diff --git a/src/scene/view/render.rs b/src/scene/view/render.rs
index e6256f8ab..143c0b1f7 100644
--- a/src/scene/view/render.rs
+++ b/src/scene/view/render.rs
@@ -4537,10 +4537,7 @@ impl Scene {
             && inst.tile_idx.is_none()
             && inst.handle != codec::Handle::NULL
         {
-            match self.document.get_entity(inst.handle) {
-                Some(EntityType::Viewport(vp)) => vp.frozen_layers.iter().cloned().collect(),
-                _ => rustc_hash::FxHashSet::default(),
-            }
+            self.viewport_hidden_handles(inst.handle)
         } else {
             rustc_hash::FxHashSet::default()
         };