From 8a29874d9f8b7fe5a642ca3bda8c2a06ec58a454 Mon Sep 17 00:00:00 2001
From: Dmitrii Troitskii <jsleitor@gmail.com>
Date: Sun, 8 Mar 2026 18:35:27 +0000
Subject: [PATCH 1/2] fix(db): infer type in coalesce() instead of returning
 BasicExpression<any>

Previously coalesce() always returned BasicExpression<any>, losing type
information. Now it uses a generic to infer the non-nullable union of all
argument types, matching the semantic of SQL COALESCE.

Fixes #1341
---
 .changeset/fix-coalesce-type.md                          | 5 +++++
 packages/db/src/query/builder/functions.ts               | 6 ++++--
 packages/db/tests/query/builder/callback-types.test-d.ts | 2 +-
 3 files changed, 10 insertions(+), 3 deletions(-)
 create mode 100644 .changeset/fix-coalesce-type.md

diff --git a/.changeset/fix-coalesce-type.md b/.changeset/fix-coalesce-type.md
new file mode 100644
index 000000000..c6e8fefd0
--- /dev/null
+++ b/.changeset/fix-coalesce-type.md
@@ -0,0 +1,5 @@
+---
+"@tanstack/db": patch
+---
+
+fix(db): infer type in coalesce() instead of returning BasicExpression<any>
diff --git a/packages/db/src/query/builder/functions.ts b/packages/db/src/query/builder/functions.ts
index 887c1468d..b11aea1fc 100644
--- a/packages/db/src/query/builder/functions.ts
+++ b/packages/db/src/query/builder/functions.ts
@@ -285,11 +285,13 @@ export function concat(
   )
 }
 
-export function coalesce(...args: Array<ExpressionLike>): BasicExpression<any> {
+export function coalesce<T extends Array<ExpressionLike>>(
+  ...args: T
+): BasicExpression<NonNullable<ExtractType<T[number]>>> {
   return new Func(
     `coalesce`,
     args.map((arg) => toExpression(arg)),
-  )
+  ) as BasicExpression<NonNullable<ExtractType<T[number]>>>
 }
 
 export function add<T1 extends ExpressionLike, T2 extends ExpressionLike>(
diff --git a/packages/db/tests/query/builder/callback-types.test-d.ts b/packages/db/tests/query/builder/callback-types.test-d.ts
index 0e901b7fb..b1565ea32 100644
--- a/packages/db/tests/query/builder/callback-types.test-d.ts
+++ b/packages/db/tests/query/builder/callback-types.test-d.ts
@@ -150,7 +150,7 @@ describe(`Query Builder Callback Types`, () => {
           BasicExpression<number>
         >()
         expectTypeOf(coalesce(user.name, `Unknown`)).toEqualTypeOf<
-          BasicExpression<any>
+          BasicExpression<string>
         >()
 
         return {

From 348a28142a2d0263b8f457f1c4b4ab686b9a09ca Mon Sep 17 00:00:00 2001
From: "autofix-ci[bot]" <114827586+autofix-ci[bot]@users.noreply.github.com>
Date: Sun, 8 Mar 2026 18:36:35 +0000
Subject: [PATCH 2/2] ci: apply automated fixes

---
 .changeset/fix-coalesce-type.md | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/.changeset/fix-coalesce-type.md b/.changeset/fix-coalesce-type.md
index c6e8fefd0..3341b355a 100644
--- a/.changeset/fix-coalesce-type.md
+++ b/.changeset/fix-coalesce-type.md
@@ -1,5 +1,5 @@
 ---
-"@tanstack/db": patch
+'@tanstack/db': patch
 ---
 
 fix(db): infer type in coalesce() instead of returning BasicExpression<any>