Extend Camino edge endpoint protocol

proto/camino/api.proto

@@ -188,6 +188,7 @@ message CaminoEdge {
   string edge_type_id = 2;
   string from_object_id = 3;
   string to_object_id = 4;
+  // Legacy canonical source-side projection fields. Prefer endpoint fields.
   string source_field = 5;
   string cardinality = 6;
   string inverse = 7;
@@ -195,6 +196,10 @@ message CaminoEdge {
   optional int32 ordinal = 9;
   string created_at = 10;
   string updated_at = 11;
+  string from_projection = 12;
+  string to_projection = 13;
+  string from_cardinality = 14;
+  string to_cardinality = 15;
 }
 
 message CaminoOp {

proto/camino/options.proto

@@ -54,9 +54,24 @@ message ConstructorOptions {
 
 message EdgeOptions {
   SymbolRef id = 1;
+  // Shorthand for other_endpoint.class.
   SymbolRef target = 2;
+  // Shorthand for this_endpoint.cardinality.
   Cardinality cardinality = 3;
+  // Shorthand for other_endpoint.projection.
   string inverse = 4;
+  EdgeEndpointOptions this_endpoint = 5;
+  EdgeEndpointOptions other_endpoint = 6;
+  repeated SymbolRef tag = 7;
+  repeated SymbolRef implements = 8;
+}
+
+message EdgeEndpointOptions {
+  SymbolRef class = 1;
+  SymbolRef interface = 2;
+  string projection = 3;
+  Cardinality cardinality = 4;
+  bool indexed = 5;
 }
 
 message MethodOptions {

proto/camino/schema.proto

@@ -25,6 +25,7 @@ enum Cardinality {
   MANY = 3;
   MANY_UNIQUE = 4;
   MANY_ORDERED = 5;
+  MANY_UNIQUE_ORDERED = 6;
 }
 
 enum DocRefStrength {
@@ -147,12 +148,26 @@ message FieldOps {
 
 message EdgeSchema {
   SymbolRef id = 1;
+  // Legacy/source-side projection fields. Prefer from_endpoint/to_endpoint.
   string source_field = 2;
   SymbolRef from_class = 3;
   SymbolRef to_class = 4;
   Cardinality cardinality = 5;
   string inverse = 6;
   repeated FieldSchema fields = 7;
+  EdgeEndpointSchema from_endpoint = 8;
+  EdgeEndpointSchema to_endpoint = 9;
+  SymbolRef declaring_class = 10;
+  repeated SymbolRef tags = 11;
+  repeated SymbolRef implements = 12;
+}
+
+message EdgeEndpointSchema {
+  SymbolRef class = 1;
+  SymbolRef interface = 2;
+  string projection = 3;
+  Cardinality cardinality = 4;
+  bool indexed = 5;
 }
 
 message MethodSchema {