Fix @> vs @>> for =properties form with PREPARE and add tests

When MATCH uses the =properties form (e.g., MATCH (n = $props)), the
enable_containment=on path correctly uses @>> (top-level containment).
The parameter fallback path unconditionally used @> (deep containment),
ignoring the use_equals flag. Fix the fallback to mirror the
enable_containment path by selecting @>> when use_equals is set.

Add regression tests for =properties form with PREPARE for both
vertices and edges, with enable_containment on and off.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: gregfelice

regress/expected/cypher_match.out

@@ -3628,9 +3628,9 @@ drop cascades to table issue_2308."T4"
 drop cascades to table issue_2308."T5"
 drop cascades to table issue_2308."R5"
 NOTICE:  graph "issue_2308" has been dropped
- drop_graph
+ drop_graph 
 ------------
-
+ 
 (1 row)
 
 -- Issue 1964
@@ -3642,9 +3642,9 @@ NOTICE:  graph "issue_2308" has been dropped
 --
 SELECT create_graph('issue_1964');
 NOTICE:  graph "issue_1964" has been created
- create_graph
+ create_graph 
 --------------
-
+ 
 (1 row)
 
 SELECT * FROM cypher('issue_1964', $$
@@ -3705,6 +3705,38 @@ EXECUTE issue_1964_vertex_on('{"props": {"name": "Alice"}}');
 (2 rows)
 
 DEALLOCATE issue_1964_vertex_on;
+-- Test =properties form with PREPARE (uses @>> top-level containment)
+SET age.enable_containment = off;
+PREPARE issue_1964_vertex_eq(agtype) AS
+    SELECT * FROM cypher('issue_1964',
+        $$MATCH (n = $props) RETURN n $$, $1) AS (p agtype);
+EXECUTE issue_1964_vertex_eq('{"props": {"name": "Alice", "age": 25}}');
+ p 
+---
+(0 rows)
+
+DEALLOCATE issue_1964_vertex_eq;
+PREPARE issue_1964_edge_eq(agtype) AS
+    SELECT * FROM cypher('issue_1964',
+        $$MATCH ()-[r = $props]->() RETURN r $$, $1) AS (p agtype);
+EXECUTE issue_1964_edge_eq('{"props": {"since": 2020}}');
+                                                                    p                                                                    
+-----------------------------------------------------------------------------------------------------------------------------------------
+ {"id": 1125899906842625, "label": "KNOWS", "end_id": 844424930131972, "start_id": 844424930131971, "properties": {"since": 2020}}::edge
+(1 row)
+
+DEALLOCATE issue_1964_edge_eq;
+-- Same with enable_containment on
+SET age.enable_containment = on;
+PREPARE issue_1964_vertex_eq_on(agtype) AS
+    SELECT * FROM cypher('issue_1964',
+        $$MATCH (n = $props) RETURN n $$, $1) AS (p agtype);
+EXECUTE issue_1964_vertex_eq_on('{"props": {"name": "Alice", "age": 25}}');
+ p 
+---
+(0 rows)
+
+DEALLOCATE issue_1964_vertex_eq_on;
 --
 -- Clean up
 --

regress/sql/cypher_match.sql

@@ -1534,6 +1534,30 @@ PREPARE issue_1964_vertex_on(agtype) AS
 EXECUTE issue_1964_vertex_on('{"props": {"name": "Alice"}}');
 DEALLOCATE issue_1964_vertex_on;
 
+-- Test =properties form with PREPARE (uses @>> top-level containment)
+SET age.enable_containment = off;
+
+PREPARE issue_1964_vertex_eq(agtype) AS
+    SELECT * FROM cypher('issue_1964',
+        $$MATCH (n = $props) RETURN n $$, $1) AS (p agtype);
+EXECUTE issue_1964_vertex_eq('{"props": {"name": "Alice", "age": 25}}');
+DEALLOCATE issue_1964_vertex_eq;
+
+PREPARE issue_1964_edge_eq(agtype) AS
+    SELECT * FROM cypher('issue_1964',
+        $$MATCH ()-[r = $props]->() RETURN r $$, $1) AS (p agtype);
+EXECUTE issue_1964_edge_eq('{"props": {"since": 2020}}');
+DEALLOCATE issue_1964_edge_eq;
+
+-- Same with enable_containment on
+SET age.enable_containment = on;
+
+PREPARE issue_1964_vertex_eq_on(agtype) AS
+    SELECT * FROM cypher('issue_1964',
+        $$MATCH (n = $props) RETURN n $$, $1) AS (p agtype);
+EXECUTE issue_1964_vertex_eq_on('{"props": {"name": "Alice", "age": 25}}');
+DEALLOCATE issue_1964_vertex_eq_on;
+
 --
 -- Clean up
 --

src/backend/parser/cypher_clause.c

@@ -4269,8 +4269,29 @@ static Node *create_property_constraints(cypher_parsestate *cpstate,
          */
         if (is_ag_node(property_constraints, cypher_param))
         {
-            return (Node *)make_op(pstate, list_make1(makeString("@>")),
-                                   prop_expr, const_expr, last_srf, -1);
+            /*
+             * Use @>> (top-level containment) for =properties form,
+             * @> (deep containment) otherwise — matching the
+             * enable_containment=on path above.
+             */
+            if ((entity->type == ENT_VERTEX &&
+                 entity->entity.node->use_equals) ||
+                ((entity->type == ENT_EDGE ||
+                  entity->type == ENT_VLE_EDGE) &&
+                 entity->entity.rel->use_equals))
+            {
+                return (Node *)make_op(pstate,
+                                       list_make1(makeString("@>>")),
+                                       prop_expr, const_expr,
+                                       last_srf, -1);
+            }
+            else
+            {
+                return (Node *)make_op(pstate,
+                                       list_make1(makeString("@>")),
+                                       prop_expr, const_expr,
+                                       last_srf, -1);
+            }
         }
         return (Node *)transform_map_to_ind(
             cpstate, entity, (cypher_map *)property_constraints);