feat(compiler): record @embed model in the catalog (RFC-012 Phase 3)

NodeType.embed_sources becomes HashMap<String, EmbedSource { source, model }>, populated from the @embed source arg + model kwarg; it round-trips through build_catalog_from_ir (the engine's IR-load path), so the recorded model reaches query execution. The migration planner already rejects any @embed change as UnsupportedChange, so changing a recorded model is a loud schema-apply refusal for free. New catalog test.

crates/omnigraph-compiler/src/catalog/mod.rs

@@ -26,6 +26,15 @@ pub struct InterfaceType {
     pub properties: HashMap<String, PropType>,
 }
 
+/// The `@embed` binding for a vector property: its source text property and,
+/// optionally, the embedding model recorded by `@embed("source", model="…")`.
+/// The model is what the query-time same-space check validates against.
+#[derive(Debug, Clone, PartialEq, Eq)]
+pub struct EmbedSource {
+    pub source: String,
+    pub model: Option<String>,
+}
+
 #[derive(Debug, Clone)]
 pub struct NodeType {
     pub name: String,
@@ -42,8 +51,8 @@ pub struct NodeType {
     pub range_constraints: Vec<RangeConstraint>,
     /// Regex check constraints
     pub check_constraints: Vec<CheckConstraint>,
-    /// Maps @embed target property -> source text property
-    pub embed_sources: HashMap<String, String>,
+    /// Maps @embed target property -> its source text property + recorded model.
+    pub embed_sources: HashMap<String, EmbedSource>,
     pub blob_properties: HashSet<String>,
     pub arrow_schema: SchemaRef,
 }
@@ -156,14 +165,18 @@ pub fn build_catalog(schema: &SchemaFile) -> Result<Catalog> {
                 if matches!(prop.prop_type.scalar, ScalarType::Blob) {
                     blob_properties.insert(prop.name.clone());
                 }
-                // Extract @embed from property annotations (stays as annotation)
-                if let Some(source_prop) = prop
-                    .annotations
-                    .iter()
-                    .find(|ann| ann.name == "embed")
-                    .and_then(|ann| ann.value.clone())
-                {
-                    embed_sources.insert(prop.name.clone(), source_prop);
+                // Extract @embed: the source text property (positional) and the
+                // optional recorded model (the `model` kwarg).
+                if let Some(ann) = prop.annotations.iter().find(|ann| ann.name == "embed") {
+                    if let Some(source) = ann.value.clone() {
+                        embed_sources.insert(
+                            prop.name.clone(),
+                            EmbedSource {
+                                source,
+                                model: ann.kwargs.get("model").cloned(),
+                            },
+                        );
+                    }
                 }
             }
 

crates/omnigraph-compiler/src/catalog/tests.rs

@@ -31,6 +31,33 @@ fn test_build_catalog() {
     assert!(catalog.node_types.contains_key("Company"));
 }
 
+#[test]
+fn test_embed_source_records_model_kwarg() {
+    let schema = parse_schema(
+        r#"
+node Doc {
+title: String
+embedding: Vector(3) @embed("title", model="openai/text-embedding-3-large")
+plain: Vector(3) @embed("title")
+}
+"#,
+    )
+    .unwrap();
+    let catalog = build_catalog(&schema).unwrap();
+    let doc = catalog.node_types.get("Doc").unwrap();
+
+    let embedding = doc.embed_sources.get("embedding").unwrap();
+    assert_eq!(embedding.source, "title");
+    assert_eq!(
+        embedding.model.as_deref(),
+        Some("openai/text-embedding-3-large")
+    );
+
+    let plain = doc.embed_sources.get("plain").unwrap();
+    assert_eq!(plain.source, "title");
+    assert_eq!(plain.model, None);
+}
+
 #[test]
 fn test_edge_lookup() {
     let schema = parse_schema(test_schema()).unwrap();

crates/omnigraph-compiler/src/query/typecheck.rs

@@ -261,13 +261,13 @@ fn typecheck_mutation(catalog: &Catalog, mutation: &Mutation, params: &[Param])
                         continue;
                     }
 
-                    if let Some(source_prop) = node_type.embed_sources.get(prop_name) {
-                        if assigned_props.contains(source_prop.as_str()) {
+                    if let Some(embed) = node_type.embed_sources.get(prop_name) {
+                        if assigned_props.contains(embed.source.as_str()) {
                             continue;
                         }
                         return Err(NanoError::Type(format!(
                             "T12: insert for `{}` must provide non-nullable property `{}` or @embed source `{}`",
-                            insert.type_name, prop_name, source_prop
+                            insert.type_name, prop_name, embed.source
                         )));
                     }