first MVP

prisma/migrations/20251114191515_connection_pair_constraints/migration.sql

@@ -0,0 +1,14 @@
+-- Enforce undirected connection uniqueness and prevent self-edges
+
+-- Prevent self-edge (A == B)
+ALTER TABLE "Connection"
+  ADD CONSTRAINT "Connection_no_self_edge"
+  CHECK ("personAId" <> "personBId");
+
+-- Unique undirected pair using functional index on LEAST/GREATEST
+-- Ensures only one edge exists for a given unordered pair {A,B}
+CREATE UNIQUE INDEX IF NOT EXISTS "Connection_undirected_pair_unique"
+ON "Connection" (
+  (LEAST("personAId","personBId")),
+  (GREATEST("personAId","personBId"))
+);