From 912a801060fd67413059fa9204f6ce61d03cc16b Mon Sep 17 00:00:00 2001
From: James Long <longster@gmail.com>
Date: Thu, 6 Aug 2026 13:58:17 -0400
Subject: [PATCH] refactor(drizzle): declare query variance (#40891)

---
 .../src/sqlite-core/effect/select.ts                |  9 +++++----
 .../src/sqlite-core/effect/session.ts               | 13 +++++++------
 2 files changed, 12 insertions(+), 10 deletions(-)

diff --git a/packages/effect-drizzle-sqlite/src/sqlite-core/effect/select.ts b/packages/effect-drizzle-sqlite/src/sqlite-core/effect/select.ts
index 0cfde54331d..0127fb09ae8 100644
--- a/packages/effect-drizzle-sqlite/src/sqlite-core/effect/select.ts
+++ b/packages/effect-drizzle-sqlite/src/sqlite-core/effect/select.ts
@@ -44,11 +44,12 @@ export type SQLiteEffectSelectPrepare<
   TEffectHKT
 >
 
+// Explicit variance prevents comparisons from recursively scanning Drizzle's conditional select types.
 export class SQLiteEffectSelectBuilder<
-  TSelection extends SelectedFields | undefined,
-  TRunResult,
-  TEffectHKT extends QueryEffectHKTBase = QueryEffectHKTBase,
-  TBuilderMode extends "db" | "qb" = "db",
+  out TSelection extends SelectedFields | undefined,
+  out TRunResult,
+  out TEffectHKT extends QueryEffectHKTBase = QueryEffectHKTBase,
+  out TBuilderMode extends "db" | "qb" = "db",
 > {
   static readonly [entityKind]: string = "SQLiteEffectSelectBuilder"
 
diff --git a/packages/effect-drizzle-sqlite/src/sqlite-core/effect/session.ts b/packages/effect-drizzle-sqlite/src/sqlite-core/effect/session.ts
index 15a56f2ca7d..ea83efe0a24 100644
--- a/packages/effect-drizzle-sqlite/src/sqlite-core/effect/session.ts
+++ b/packages/effect-drizzle-sqlite/src/sqlite-core/effect/session.ts
@@ -303,10 +303,11 @@ export class SQLiteEffectPreparedQuery<
   }
 }
 
+// Explicit variance prevents comparisons from recursively scanning the full Drizzle query-builder graph.
 export abstract class SQLiteEffectSession<
-  TEffectHKT extends QueryEffectHKTBase = QueryEffectHKTBase,
-  TRunResult = unknown,
-  TRelations extends AnyRelations = EmptyRelations,
+  out TEffectHKT extends QueryEffectHKTBase = QueryEffectHKTBase,
+  out TRunResult = unknown,
+  out TRelations extends AnyRelations = EmptyRelations,
 > {
   static readonly [entityKind]: string = "SQLiteEffectSession"
 
@@ -404,9 +405,9 @@ export abstract class SQLiteEffectSession<
 }
 
 export abstract class SQLiteEffectTransaction<
-  TEffectHKT extends QueryEffectHKTBase,
-  TRunResult,
-  TRelations extends AnyRelations = EmptyRelations,
+  out TEffectHKT extends QueryEffectHKTBase,
+  out TRunResult,
+  out TRelations extends AnyRelations = EmptyRelations,
 > extends SQLiteEffectDatabase<TEffectHKT, TRunResult, TRelations> {
   static override readonly [entityKind]: string = "SQLiteEffectTransaction"