Add prim status and model-hierarchy queries

Cargo.toml

@@ -15,6 +15,7 @@ serde = ["dep:serde", "half/serde"]
 
 [dependencies]
 anyhow = "1.0.79"
+bitflags = "2.11.1"
 bytemuck = { version = "1.14.0", features = ["derive"] }
 strum = { version = "0.28.0", features = ["derive"] }
 thiserror = "2"

ROADMAP.md

@@ -99,8 +99,8 @@ Legend: :white_check_mark: Supported | :construction: Planned | :thinking: Consi
 | Ordered property children | `11.3.2` | :white_check_mark: | `0.2.0` | Merged `propertyChildren` |
 | Ordered property children (`propertyOrder` reordering) | `11.3.2` | :white_check_mark: | `main` | Strongest opinion applied via `sdf::apply_ordering` |
 | [Scene graph instancing](https://openusd.org/release/glossary.html#usdglossary-instancing) | `11.3.3` | :construction: | | `instanceable` readable; shared representation not implemented |
-| Model hierarchy (kind) | `11.4` | :construction: | | `kind` readable; hierarchy validation not implemented |
-| [Stage queries](https://openusd.org/release/api/prim_flags_8h.html) (Active, Loaded, Defined, Abstract, Instance) | `11.5` | :construction: | | Predicate flags for traversal filtering |
+| Model hierarchy (kind) | `11.4` | :white_check_mark: | `main` | `Stage::is_model`/`is_group`/`is_component`/`is_subcomponent` validate the contiguous kind hierarchy |
+| [Stage queries](https://openusd.org/release/api/prim_flags_8h.html) (Active, Loaded, Defined, Abstract, Instance) | `11.5` | :white_check_mark: | `main` | `Stage::is_active`/`is_loaded`/`is_defined`/`is_abstract`/`is_instance` and `prim_status`; load rules pending |
 | [Session layer](https://openusd.org/release/glossary.html#usdglossary-sessionlayer) | `11.2` | :white_check_mark: | `0.3.0` | `StageBuilder::session_layer` |
 
 ## Value Resolution (Spec 12)

fixtures/stage_queries.usda

@@ -0,0 +1,91 @@
+#usda 1.0
+(
+    defaultPrim = "World"
+)
+
+def Scope "World" (
+    kind = "assembly"
+)
+{
+    def Scope "ActiveParent"
+    {
+        def Scope "Child"
+        {
+        }
+    }
+
+    def Scope "InactiveParent" (
+        active = false
+    )
+    {
+        def Scope "Child" (
+            active = true
+        )
+        {
+        }
+    }
+
+    over "OverOnly"
+    {
+    }
+
+    over "OverParent"
+    {
+        def Scope "Child"
+        {
+        }
+    }
+
+    class "ClassParent"
+    {
+        def Scope "Child"
+        {
+        }
+    }
+
+    def Scope "Group" (
+        kind = "group"
+    )
+    {
+        def Scope "Component" (
+            kind = "component"
+        )
+        {
+        }
+
+        def Scope "Subcomponent" (
+            kind = "subcomponent"
+        )
+        {
+        }
+    }
+
+    def Scope "InvalidComponentParent"
+    {
+        def Scope "Component" (
+            kind = "component"
+        )
+        {
+        }
+    }
+
+    def Scope "Instance" (
+        instanceable = true
+        references = </World/Prototype>
+    )
+    {
+    }
+
+    def Scope "InstanceableNoArc" (
+        instanceable = true
+    )
+    {
+    }
+
+    def Scope "Prototype"
+    {
+        def Scope "ReferencedChild"
+        {
+        }
+    }
+}

src/lib.rs

@@ -43,7 +43,7 @@ pub mod usdz;
 
 pub use half::f16;
 pub use layer::{DependencyKind, LayerFormat};
-pub use stage::{Stage, StageBuilder};
+pub use stage::{PrimStatus, Stage, StageBuilder};
 
 /// A recoverable error encountered during stage composition.
 ///

src/pcp/cache.rs

@@ -118,6 +118,12 @@ impl Cache {
         Ok(None)
     }
 
+    /// Returns `true` if the composed prim index contains any non-local arc.
+    pub(crate) fn has_composition_arc(&mut self, path: &Path) -> Result<bool> {
+        self.ensure_index(path)?;
+        Ok(self.indices.get(path).is_some_and(|index| index.has_composition_arc()))
+    }
+
     /// Resolves a field value from the strongest opinion across all composition nodes.
     pub fn resolve_field(&mut self, path: &Path, field: &str) -> Result<Option<Value>> {
         if path.is_property_path() {

src/pcp/index.rs

@@ -166,6 +166,11 @@ impl PrimIndex {
         self.graph.is_empty()
     }
 
+    /// Returns `true` if any node was introduced by a composition arc.
+    pub(crate) fn has_composition_arc(&self) -> bool {
+        self.nodes().iter().any(|node| node.arc != ArcType::Root)
+    }
+
     /// Returns the nodes in strength order (index 0 = strongest).
     pub fn nodes(&self) -> &[Node] {
         &self.graph

src/sdf/value.rs

@@ -332,6 +332,7 @@ impl_try_from_value!(i64, try_as_int_64, "Int64");
 impl_try_from_value!(u64, try_as_uint_64, "Uint64");
 impl_try_from_value!(f32, try_as_float, "Float");
 impl_try_from_value!(f64, try_as_double, "Double");
+impl_try_from_value!(Specifier, try_as_specifier, "Specifier");
 impl_try_from_value!(ReferenceListOp, try_as_reference_list_op, "ReferenceListOp");
 impl_try_from_value!(PayloadListOp, try_as_payload_list_op, "PayloadListOp");
 impl_try_from_value!(PathListOp, try_as_path_list_op, "PathListOp");