diff --git a/Cargo.lock b/Cargo.lock
index f85069b6b..7b66c0e6f 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -72,7 +72,7 @@ checksum = "366ffbaa4442f4684d91e2cd7c5ea7c4ed8add41959a31447066e279e432b618"
 [[package]]
 name = "acadrust"
 version = "0.4.1"
-source = "git+https://git@github.com/HakanSeven12/cadcodec.git?rev=3a87743ad7b0fc74f0137ccd48f598116e2904b0#3a87743ad7b0fc74f0137ccd48f598116e2904b0"
+source = "git+https://git@github.com/HakanSeven12/cadcodec.git?rev=c91a1c1de89a0fbc006dc360ddb0251ac8c207d1#c91a1c1de89a0fbc006dc360ddb0251ac8c207d1"
 dependencies = [
  "ahash 0.8.12",
  "anyhow",
diff --git a/Cargo.toml b/Cargo.toml
index 74f7792a8..79f2cf17a 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -27,7 +27,7 @@ glam = { version = "0.33", features = ["bytemuck"] }
 rfd = "0.17"
 clap = { version = "4", features = ["derive"] }
 env_logger = "0.11"
-acadrust = { git = "https://github.com/HakanSeven12/cadcodec.git", rev = "3a87743ad7b0fc74f0137ccd48f598116e2904b0", features = ["serde"] }
+acadrust = { git = "https://github.com/HakanSeven12/cadcodec.git", rev = "c91a1c1de89a0fbc006dc360ddb0251ac8c207d1", features = ["serde"] }
 cadkernel = { git = "https://github.com/HakanSeven12/cadkernel.git", rev = "48c634995fa60d3928c37bae49b12b421c56c886", features = ["acis", "offset"] }
 dwg-thumbnailer = { path = "crates/dwg-thumbnailer" }
 flate2 = "1"
@@ -61,7 +61,7 @@ iced_core = { git = "https://github.com/iced-rs/iced.git", rev = "23604ff22ab0aa
 iced_widget = { git = "https://github.com/iced-rs/iced.git", rev = "23604ff22ab0aad9e00b9327cb7b8546ed84db39" }
 
 [patch."https://github.com/HakanSeven12/cadcodec.git"]
-acadrust = { git = "https://git@github.com/HakanSeven12/cadcodec.git", rev = "3a87743ad7b0fc74f0137ccd48f598116e2904b0" }
+acadrust = { git = "https://git@github.com/HakanSeven12/cadcodec.git", rev = "c91a1c1de89a0fbc006dc360ddb0251ac8c207d1" }
 
 
 [target.'cfg(not(target_arch = "wasm32"))'.dependencies]
diff --git a/crates/ocs_plugin_api/Cargo.toml b/crates/ocs_plugin_api/Cargo.toml
index bd69e4060..49e520059 100644
--- a/crates/ocs_plugin_api/Cargo.toml
+++ b/crates/ocs_plugin_api/Cargo.toml
@@ -14,7 +14,7 @@ serde = { version = "1", features = ["derive"] }
 # Pulled in only by the `host` feature, which adds the `acadrust`-typed
 # `HostApi` runtime surface. The default crate stays dependency-free so engine
 # crates and external tooling can depend on the manifest/ribbon contract cheaply.
-acadrust = { git = "https://github.com/HakanSeven12/cadcodec.git", rev = "3a87743ad7b0fc74f0137ccd48f598116e2904b0", optional = true, features = ["serde"] }
+acadrust = { git = "https://github.com/HakanSeven12/cadcodec.git", rev = "c91a1c1de89a0fbc006dc360ddb0251ac8c207d1", optional = true, features = ["serde"] }
 
 # Runtime IPC and serialization (host feature only).
 interprocess = { version = "2", optional = true }
@@ -37,7 +37,7 @@ serde_json = "1"
 serde = { version = "1", features = ["derive"] }
 cargo-lock = "11"
 # acadrust is scanned at build time to generate the embedded type registry.
-acadrust = { git = "https://github.com/HakanSeven12/cadcodec.git", rev = "3a87743ad7b0fc74f0137ccd48f598116e2904b0", features = ["serde"] }
+acadrust = { git = "https://github.com/HakanSeven12/cadcodec.git", rev = "c91a1c1de89a0fbc006dc360ddb0251ac8c207d1", features = ["serde"] }
 
 [dev-dependencies]
 serde_json = "1"
diff --git a/crates/ocs_plugin_api/build.rs b/crates/ocs_plugin_api/build.rs
index d818a0dd6..87b9bafb9 100644
--- a/crates/ocs_plugin_api/build.rs
+++ b/crates/ocs_plugin_api/build.rs
@@ -123,6 +123,10 @@ fn add_enum_samples(tracer: &mut Tracer, samples: &mut Samples) {
     let _ = tracer.trace_value(samples, &acadrust::LineWeight::Default);
     let _ = tracer.trace_value(samples, &acadrust::LineWeight::Value(0));
 
+    let _ = tracer.trace_value(samples, &acadrust::Transparency::BY_LAYER);
+    let _ = tracer.trace_value(samples, &acadrust::Transparency::BY_BLOCK);
+    let _ = tracer.trace_value(samples, &acadrust::Transparency::OPAQUE);
+
     let _ = tracer.trace_value(samples, &acadrust::entities::SmoothSurfaceType::None);
     let _ = tracer.trace_value(
         samples,
diff --git a/crates/ocs_web_worker/Cargo.toml b/crates/ocs_web_worker/Cargo.toml
index bef08417a..a700c08c3 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]
-acadrust = { git = "https://github.com/HakanSeven12/cadcodec.git", rev = "3a87743ad7b0fc74f0137ccd48f598116e2904b0", features = ["serde"] }
+acadrust = { git = "https://github.com/HakanSeven12/cadcodec.git", rev = "c91a1c1de89a0fbc006dc360ddb0251ac8c207d1", features = ["serde"] }
 bincode = "1.3"
 serde = { version = "1", features = ["derive"] }
 console_error_panic_hook = "0.1"
diff --git a/src/entities/raster_image.rs b/src/entities/raster_image.rs
index 51937cf58..c91aaf793 100644
--- a/src/entities/raster_image.rs
+++ b/src/entities/raster_image.rs
@@ -290,7 +290,7 @@ impl PropertyEditable for RasterImage {
             .flags
             .contains(acadrust::entities::ImageDisplayFlags::USE_CLIPPING_BOUNDARY);
         let clip_inverted = self.clip_boundary.clip_mode == acadrust::entities::ClipMode::Inside;
-        let transparency = format!("{:.0}%", self.common.transparency.as_percent() * 100.0);
+        let transparency = self.common.transparency.to_string();
         vec![
             PropSection {
                 title: t!("Geometry").into_owned(),
diff --git a/src/scene/cache/block_cache.rs b/src/scene/cache/block_cache.rs
index f38ba11c5..aaf12f4da 100644
--- a/src/scene/cache/block_cache.rs
+++ b/src/scene/cache/block_cache.rs
@@ -88,6 +88,7 @@ pub struct LocalWire {
     /// `points.is_empty() && !fill_tris.is_empty()`.
     pub is_fill_only: bool,
     pub color_is_byblock: bool,
+    pub transparency_is_byblock: bool,
     pub lt_is_byblock: bool,
     pub lw_is_byblock: bool,
     /// Set when this child sits on layer "0" and the matching property is
@@ -710,7 +711,8 @@ fn tessellate_sub_local(
         .unwrap_or(true);
     let color_l0 =
         !has_book_color && on_l0 && sub.common().color == AcadColor::ByLayer;
-    let transparency_l0 = on_l0 && sub.common().transparency.alpha() == 0;
+    let transparency_is_byblock = sub.common().transparency.is_by_block();
+    let transparency_l0 = on_l0 && sub.common().transparency.is_by_layer();
     let lt_l0 = on_l0 && {
         let lt = &sub.common().linetype;
         lt.is_empty() || lt.eq_ignore_ascii_case("bylayer")
@@ -846,10 +848,11 @@ fn tessellate_sub_local(
             hide_unselected: frame_mode == Some(0),
             is_fill_only,
             color_is_byblock: color_is_byblock && wire_on_base_color,
+            transparency_is_byblock,
             lt_is_byblock,
             lw_is_byblock,
             color_l0: color_l0 && wire_on_base_color,
-            transparency_l0: transparency_l0 && wire_on_base_color,
+            transparency_l0,
             lt_l0,
             lw_l0,
             aabb_local,
@@ -1990,24 +1993,28 @@ fn expand_defn(
 /// layer-0 rule → insert-layer colour, else the cached colour; finally xref
 /// fade. Shared by the stroke, fill, and greeked-text emit paths.
 fn resolve_wire_color(lw: &LocalWire, ctx: &ExpandCtx) -> [f32; 4] {
-    let c = if ctx.selected {
+    let mut color = if ctx.selected {
         WireModel::SELECTED
     } else if lw.color_is_byblock {
         ctx.ins_color
     } else if lw.color_l0 {
-        let alpha = if lw.transparency_l0 {
+        ctx.l0.color
+    } else {
+        lw.color
+    };
+    if !ctx.selected {
+        color[3] = if lw.transparency_is_byblock {
+            ctx.ins_color[3]
+        } else if lw.transparency_l0 {
             ctx.l0.color[3]
         } else {
             lw.color[3]
         };
-        [ctx.l0.color[0], ctx.l0.color[1], ctx.l0.color[2], alpha]
-    } else {
-        lw.color
-    };
+    }
     if ctx.is_xref && !ctx.selected {
-        fade_toward_bg(c, ctx.bg_color)
+        fade_toward_bg(color, ctx.bg_color)
     } else {
-        c
+        color
     }
 }
 
@@ -2592,7 +2599,7 @@ fn emit_wire(
             pos: [hx, hy, hz],
             pos_low: [lx, ly, lz],
             uv: tv.uv,
-            color: [rgb[0], rgb[1], rgb[2], tv.color[3]],
+            color: [rgb[0], rgb[1], rgb[2], final_color[3]],
             draw_depth: tv.draw_depth,
         });
     }
diff --git a/src/scene/cache/properties.rs b/src/scene/cache/properties.rs
index 8b3d04711..1e463ccd8 100644
--- a/src/scene/cache/properties.rs
+++ b/src/scene/cache/properties.rs
@@ -1,4 +1,4 @@
-use acadrust::{EntityType, Handle};
+use acadrust::{EntityType, Handle, Transparency};
 use crate::t;
 
 use crate::scene::model::object::{PropSection, PropValue, Property};
@@ -10,15 +10,12 @@ pub fn general_section(entity: &EntityType) -> PropSection {
     } else {
         common.linetype.clone()
     };
-    // Alpha 0 is ByLayer, Alpha 1 is ByBlock; show them by name and fall back
-    // to a rounded percentage for explicit values.
-    let transp_display = match common.transparency.alpha() {
-        0 => "ByLayer".to_string(),
-        1 => "ByBlock".to_string(),
-        alpha => format!(
-            "{}",
-            (alpha as f64 / 255.0 * 100.0).round() as u32
-        ),
+    let transp_display = match common.transparency {
+        Transparency::ByLayer => "ByLayer".to_string(),
+        Transparency::ByBlock => "ByBlock".to_string(),
+        Transparency::Explicit(alpha) => {
+            ((alpha as f64 / 255.0 * 100.0).round() as u32).to_string()
+        }
     };
 
     // Hyperlink is stored in XDATA under the "PE_URL" application.
diff --git a/src/scene/render_graph.rs b/src/scene/render_graph.rs
index dd737aaef..69400ad4f 100644
--- a/src/scene/render_graph.rs
+++ b/src/scene/render_graph.rs
@@ -67,6 +67,8 @@ pub struct InsertStyleSpec {
     own: BlockStyle,
     color_byblock: bool,
     color_bylayer: bool,
+    transparency_byblock: bool,
+    transparency_bylayer: bool,
     linetype_byblock: bool,
     linetype_bylayer: bool,
     lineweight_byblock: bool,
@@ -83,6 +85,8 @@ impl InsertStyleSpec {
             own: BlockStyle::for_entity(document, &entity, viewport),
             color_byblock: !has_book_color && insert.common.color == Color::ByBlock,
             color_bylayer: !has_book_color && insert.common.color == Color::ByLayer,
+            transparency_byblock: insert.common.transparency.is_by_block(),
+            transparency_bylayer: insert.common.transparency.is_by_layer(),
             linetype_byblock: linetype.eq_ignore_ascii_case("byblock"),
             linetype_bylayer: linetype.is_empty() || linetype.eq_ignore_ascii_case("bylayer"),
             lineweight_byblock: matches!(
@@ -101,12 +105,23 @@ impl InsertStyleSpec {
     pub fn resolve(self, parent: BlockStyle) -> BlockStyle {
         let mut insert = self.own.insert;
         if self.color_byblock {
-            insert.0 = parent.insert.0;
+            insert.0[0] = parent.insert.0[0];
+            insert.0[1] = parent.insert.0[1];
+            insert.0[2] = parent.insert.0[2];
             insert.4 = parent.insert.4;
         } else if self.layer0 && self.color_bylayer {
-            insert.0 = parent.layer0.color;
+            insert.0[0] = parent.layer0.color[0];
+            insert.0[1] = parent.layer0.color[1];
+            insert.0[2] = parent.layer0.color[2];
             insert.4 = parent.layer0_aci;
         }
+        insert.0[3] = if self.transparency_byblock {
+            parent.insert.0[3]
+        } else if self.layer0 && self.transparency_bylayer {
+            parent.layer0.color[3]
+        } else {
+            insert.0[3]
+        };
         if self.linetype_byblock {
             insert.1 = parent.insert.1;
             insert.2 = parent.insert.2;
diff --git a/src/scene/selection.rs b/src/scene/selection.rs
index 925b7d93d..0c67902e7 100644
--- a/src/scene/selection.rs
+++ b/src/scene/selection.rs
@@ -675,11 +675,12 @@ impl Scene {
                 .to_string(),
             ),
             "lineweight" => Some(Self::format_lineweight(entity.common().line_weight)),
-            "transparency" => Some(if entity.common().transparency.alpha() == 0 {
-                "ByLayer".to_string()
-            } else {
-                ((entity.common().transparency.alpha() as f64 / 255.0 * 100.0).round() as u32)
-                    .to_string()
+            "transparency" => Some(match entity.common().transparency {
+                acadrust::types::Transparency::ByLayer => "ByLayer".to_string(),
+                acadrust::types::Transparency::ByBlock => "ByBlock".to_string(),
+                acadrust::types::Transparency::Explicit(alpha) => {
+                    ((alpha as f64 / 255.0 * 100.0).round() as u32).to_string()
+                }
             }),
             "hyperlink" => Some(
                 entity
diff --git a/src/scene/view/dispatch.rs b/src/scene/view/dispatch.rs
index 34c441329..4c47da101 100644
--- a/src/scene/view/dispatch.rs
+++ b/src/scene/view/dispatch.rs
@@ -137,9 +137,13 @@ pub fn apply_common_prop(entity: &mut EntityType, field: &str, value: &str) {
         "transparency" => {
             let s = value.trim();
             if s.eq_ignore_ascii_case("ByLayer") {
-                entity.as_entity_mut().set_transparency(Transparency::new(0));
+                entity
+                    .as_entity_mut()
+                    .set_transparency(Transparency::BY_LAYER);
             } else if s.eq_ignore_ascii_case("ByBlock") {
-                entity.as_entity_mut().set_transparency(Transparency::new(1));
+                entity
+                    .as_entity_mut()
+                    .set_transparency(Transparency::BY_BLOCK);
             } else {
                 let clean = s.trim_end_matches('%').trim();
                 if let Ok(pct) = clean.parse::<f64>() {
diff --git a/src/scene/view/render.rs b/src/scene/view/render.rs
index c2d8d2f2b..de64fc1df 100644
--- a/src/scene/view/render.rs
+++ b/src/scene/view/render.rs
@@ -2863,7 +2863,7 @@ pub(crate) fn render_style_for_viewport(
             _ => 0,
         };
         let [r, g, b, _] = tess_util::aci_to_rgba(resolved);
-        let transparency = if common.transparency.alpha() == 0 {
+        let transparency = if common.transparency.is_by_layer() {
             viewport_override(
                 document,
                 layer_name,
@@ -3077,18 +3077,21 @@ pub(crate) fn render_style_for_block_sub_viewport(
     let on_l0 = is_effective_layer_zero(&common.layer);
 
     let has_book_color = has_resolved_book_color(document, e);
-    let final_color = if !has_book_color && common.color == AcadColor::ByBlock {
+    let resolved_rgb = if !has_book_color && common.color == AcadColor::ByBlock {
         insert_color
     } else if !has_book_color && on_l0 && common.color == AcadColor::ByLayer {
-        let alpha = if common.transparency.alpha() == 0 {
-            l0.color[3]
-        } else {
-            color[3]
-        };
-        [l0.color[0], l0.color[1], l0.color[2], alpha]
+        l0.color
     } else {
         color
     };
+    let alpha = if common.transparency.is_by_block() {
+        insert_color[3]
+    } else if on_l0 && common.transparency.is_by_layer() {
+        l0.color[3]
+    } else {
+        color[3]
+    };
+    let final_color = [resolved_rgb[0], resolved_rgb[1], resolved_rgb[2], alpha];
 
     let lt_bylayer =
         common.linetype.is_empty() || common.linetype.eq_ignore_ascii_case("bylayer");
@@ -4319,4 +4322,22 @@ mod layer0_inherit_tests {
         assert_eq!(&c[..3], &walls[..3], "RGB inherited from the insert layer");
         assert!((c[3] - 0.5).abs() < 0.02, "child's own 50% transparency is kept, got {}", c[3]);
     }
+
+    #[test]
+    fn byblock_transparency_inherits_insert_alpha() {
+        let d = doc();
+        let mut entity = child("Other", Color::Index(3));
+        entity.common_mut().transparency = Transparency::BY_BLOCK;
+        let color = resolve(&d, &entity, [0.2, 0.4, 0.6, 0.25]);
+        assert_eq!(color[3], 0.25);
+    }
+
+    #[test]
+    fn explicit_opaque_does_not_inherit_alpha() {
+        let d = doc();
+        let mut entity = child("0", Color::ByLayer);
+        entity.common_mut().transparency = Transparency::OPAQUE;
+        let color = resolve(&d, &entity, [0.2, 0.4, 0.6, 0.25]);
+        assert_eq!(color[3], 1.0);
+    }
 }