diff --git a/packages/svelte-query-devtools/package.json b/packages/svelte-query-devtools/package.json
index 684db1bcbe..43573adeaf 100644
--- a/packages/svelte-query-devtools/package.json
+++ b/packages/svelte-query-devtools/package.json
@@ -22,7 +22,12 @@
   "scripts": {
     "clean": "premove ./dist ./coverage ./.svelte-kit ./dist-ts",
     "compile": "tsc --project tsconfig.json",
-    "test:types": "svelte-check --tsconfig ./tsconfig.json",
+    "test:types": "npm-run-all --serial test:types:*",
+    "test:types:ts56": "node -e \"const Module = require('module'); const resolveFilename = Module._resolveFilename; let swapped = false; Module._resolveFilename = function (request, ...args) { if (request === 'typescript' || request.startsWith('typescript/')) { request = request.replace('typescript', 'typescript56'); swapped = true } return resolveFilename.call(this, request, ...args) }; process.on('exit', () => { if (!swapped) { console.error('svelte-check did not load typescript56'); process.exitCode = 1 } }); process.argv.splice(1, 0, ''); require('svelte-check/bin/svelte-check')\" -- --tsconfig ./tsconfig.legacy.json",
+    "test:types:ts57": "node -e \"const Module = require('module'); const resolveFilename = Module._resolveFilename; let swapped = false; Module._resolveFilename = function (request, ...args) { if (request === 'typescript' || request.startsWith('typescript/')) { request = request.replace('typescript', 'typescript57'); swapped = true } return resolveFilename.call(this, request, ...args) }; process.on('exit', () => { if (!swapped) { console.error('svelte-check did not load typescript57'); process.exitCode = 1 } }); process.argv.splice(1, 0, ''); require('svelte-check/bin/svelte-check')\" -- --tsconfig ./tsconfig.legacy.json",
+    "test:types:ts58": "node -e \"const Module = require('module'); const resolveFilename = Module._resolveFilename; let swapped = false; Module._resolveFilename = function (request, ...args) { if (request === 'typescript' || request.startsWith('typescript/')) { request = request.replace('typescript', 'typescript58'); swapped = true } return resolveFilename.call(this, request, ...args) }; process.on('exit', () => { if (!swapped) { console.error('svelte-check did not load typescript58'); process.exitCode = 1 } }); process.argv.splice(1, 0, ''); require('svelte-check/bin/svelte-check')\" -- --tsconfig ./tsconfig.legacy.json",
+    "test:types:ts59": "node -e \"const Module = require('module'); const resolveFilename = Module._resolveFilename; let swapped = false; Module._resolveFilename = function (request, ...args) { if (request === 'typescript' || request.startsWith('typescript/')) { request = request.replace('typescript', 'typescript59'); swapped = true } return resolveFilename.call(this, request, ...args) }; process.on('exit', () => { if (!swapped) { console.error('svelte-check did not load typescript59'); process.exitCode = 1 } }); process.argv.splice(1, 0, ''); require('svelte-check/bin/svelte-check')\" -- --tsconfig ./tsconfig.legacy.json",
+    "test:types:tscurrent": "svelte-check --tsconfig ./tsconfig.json",
     "test:eslint": "eslint --concurrency=auto ./src",
     "test:lib": "vitest",
     "test:lib:dev": "pnpm run test:lib --watch",
@@ -58,6 +63,7 @@
     "@testing-library/svelte": "^5.2.8",
     "@typescript-eslint/parser": "^8.70.1",
     "eslint-plugin-svelte": "^3.23.0",
+    "npm-run-all2": "^9.0.3",
     "svelte": "^5.57.1",
     "svelte-check": "^4.4.5",
     "typescript": "catalog:"
diff --git a/packages/svelte-query-devtools/tsconfig.legacy.json b/packages/svelte-query-devtools/tsconfig.legacy.json
new file mode 100644
index 0000000000..d806972e30
--- /dev/null
+++ b/packages/svelte-query-devtools/tsconfig.legacy.json
@@ -0,0 +1,8 @@
+{
+  "extends": "./tsconfig.json",
+  "compilerOptions": {
+    "outDir": "./dist-ts/legacy"
+  },
+  "include": ["src"],
+  "references": [{ "path": "../query-devtools" }, { "path": "../svelte-query" }]
+}
diff --git a/packages/svelte-query-persist-client/package.json b/packages/svelte-query-persist-client/package.json
index 7b80fd6669..5f1eee7e8b 100644
--- a/packages/svelte-query-persist-client/package.json
+++ b/packages/svelte-query-persist-client/package.json
@@ -22,7 +22,12 @@
   "scripts": {
     "clean": "premove ./dist ./coverage ./.svelte-kit ./dist-ts",
     "compile": "tsc --project tsconfig.json",
-    "test:types": "svelte-check --tsconfig ./tsconfig.json",
+    "test:types": "npm-run-all --serial test:types:*",
+    "test:types:ts56": "node -e \"const Module = require('module'); const resolveFilename = Module._resolveFilename; let swapped = false; Module._resolveFilename = function (request, ...args) { if (request === 'typescript' || request.startsWith('typescript/')) { request = request.replace('typescript', 'typescript56'); swapped = true } return resolveFilename.call(this, request, ...args) }; process.on('exit', () => { if (!swapped) { console.error('svelte-check did not load typescript56'); process.exitCode = 1 } }); process.argv.splice(1, 0, ''); require('svelte-check/bin/svelte-check')\" -- --tsconfig ./tsconfig.legacy.json",
+    "test:types:ts57": "node -e \"const Module = require('module'); const resolveFilename = Module._resolveFilename; let swapped = false; Module._resolveFilename = function (request, ...args) { if (request === 'typescript' || request.startsWith('typescript/')) { request = request.replace('typescript', 'typescript57'); swapped = true } return resolveFilename.call(this, request, ...args) }; process.on('exit', () => { if (!swapped) { console.error('svelte-check did not load typescript57'); process.exitCode = 1 } }); process.argv.splice(1, 0, ''); require('svelte-check/bin/svelte-check')\" -- --tsconfig ./tsconfig.legacy.json",
+    "test:types:ts58": "node -e \"const Module = require('module'); const resolveFilename = Module._resolveFilename; let swapped = false; Module._resolveFilename = function (request, ...args) { if (request === 'typescript' || request.startsWith('typescript/')) { request = request.replace('typescript', 'typescript58'); swapped = true } return resolveFilename.call(this, request, ...args) }; process.on('exit', () => { if (!swapped) { console.error('svelte-check did not load typescript58'); process.exitCode = 1 } }); process.argv.splice(1, 0, ''); require('svelte-check/bin/svelte-check')\" -- --tsconfig ./tsconfig.legacy.json",
+    "test:types:ts59": "node -e \"const Module = require('module'); const resolveFilename = Module._resolveFilename; let swapped = false; Module._resolveFilename = function (request, ...args) { if (request === 'typescript' || request.startsWith('typescript/')) { request = request.replace('typescript', 'typescript59'); swapped = true } return resolveFilename.call(this, request, ...args) }; process.on('exit', () => { if (!swapped) { console.error('svelte-check did not load typescript59'); process.exitCode = 1 } }); process.argv.splice(1, 0, ''); require('svelte-check/bin/svelte-check')\" -- --tsconfig ./tsconfig.legacy.json",
+    "test:types:tscurrent": "svelte-check --tsconfig ./tsconfig.json",
     "test:eslint": "eslint --concurrency=auto ./src ./tests",
     "test:lib": "vitest",
     "test:lib:dev": "pnpm run test:lib --watch",
@@ -59,6 +64,7 @@
     "@testing-library/svelte": "^5.2.8",
     "@typescript-eslint/parser": "^8.70.1",
     "eslint-plugin-svelte": "^3.23.0",
+    "npm-run-all2": "^9.0.3",
     "svelte": "^5.57.1",
     "svelte-check": "^4.4.5",
     "typescript": "catalog:"
diff --git a/packages/svelte-query-persist-client/tsconfig.legacy.json b/packages/svelte-query-persist-client/tsconfig.legacy.json
new file mode 100644
index 0000000000..0e63b18925
--- /dev/null
+++ b/packages/svelte-query-persist-client/tsconfig.legacy.json
@@ -0,0 +1,11 @@
+{
+  "extends": "./tsconfig.json",
+  "compilerOptions": {
+    "outDir": "./dist-ts/legacy"
+  },
+  "include": ["src"],
+  "references": [
+    { "path": "../query-persist-client-core" },
+    { "path": "../svelte-query" }
+  ]
+}
diff --git a/packages/svelte-query/package.json b/packages/svelte-query/package.json
index 18e16225a7..1e128958f1 100644
--- a/packages/svelte-query/package.json
+++ b/packages/svelte-query/package.json
@@ -22,7 +22,12 @@
   "scripts": {
     "clean": "premove ./dist ./coverage ./.svelte-kit ./dist-ts",
     "compile": "tsc --project tsconfig.json",
-    "test:types": "svelte-check --tsconfig ./tsconfig.json",
+    "test:types": "npm-run-all --serial test:types:*",
+    "test:types:ts56": "node -e \"const Module = require('module'); const resolveFilename = Module._resolveFilename; let swapped = false; Module._resolveFilename = function (request, ...args) { if (request === 'typescript' || request.startsWith('typescript/')) { request = request.replace('typescript', 'typescript56'); swapped = true } return resolveFilename.call(this, request, ...args) }; process.on('exit', () => { if (!swapped) { console.error('svelte-check did not load typescript56'); process.exitCode = 1 } }); process.argv.splice(1, 0, ''); require('svelte-check/bin/svelte-check')\" -- --tsconfig ./tsconfig.legacy.json",
+    "test:types:ts57": "node -e \"const Module = require('module'); const resolveFilename = Module._resolveFilename; let swapped = false; Module._resolveFilename = function (request, ...args) { if (request === 'typescript' || request.startsWith('typescript/')) { request = request.replace('typescript', 'typescript57'); swapped = true } return resolveFilename.call(this, request, ...args) }; process.on('exit', () => { if (!swapped) { console.error('svelte-check did not load typescript57'); process.exitCode = 1 } }); process.argv.splice(1, 0, ''); require('svelte-check/bin/svelte-check')\" -- --tsconfig ./tsconfig.legacy.json",
+    "test:types:ts58": "node -e \"const Module = require('module'); const resolveFilename = Module._resolveFilename; let swapped = false; Module._resolveFilename = function (request, ...args) { if (request === 'typescript' || request.startsWith('typescript/')) { request = request.replace('typescript', 'typescript58'); swapped = true } return resolveFilename.call(this, request, ...args) }; process.on('exit', () => { if (!swapped) { console.error('svelte-check did not load typescript58'); process.exitCode = 1 } }); process.argv.splice(1, 0, ''); require('svelte-check/bin/svelte-check')\" -- --tsconfig ./tsconfig.legacy.json",
+    "test:types:ts59": "node -e \"const Module = require('module'); const resolveFilename = Module._resolveFilename; let swapped = false; Module._resolveFilename = function (request, ...args) { if (request === 'typescript' || request.startsWith('typescript/')) { request = request.replace('typescript', 'typescript59'); swapped = true } return resolveFilename.call(this, request, ...args) }; process.on('exit', () => { if (!swapped) { console.error('svelte-check did not load typescript59'); process.exitCode = 1 } }); process.argv.splice(1, 0, ''); require('svelte-check/bin/svelte-check')\" -- --tsconfig ./tsconfig.legacy.json",
+    "test:types:tscurrent": "svelte-check --tsconfig ./tsconfig.json",
     "test:eslint": "eslint --concurrency=auto ./src ./tests",
     "test:lib": "vitest",
     "test:lib:dev": "pnpm run test:lib --watch",
@@ -58,6 +63,7 @@
     "@testing-library/svelte": "^5.2.8",
     "@typescript-eslint/parser": "^8.70.1",
     "eslint-plugin-svelte": "^3.23.0",
+    "npm-run-all2": "^9.0.3",
     "svelte": "^5.57.1",
     "svelte-check": "^4.4.5",
     "typescript": "catalog:"
diff --git a/packages/svelte-query/tsconfig.legacy.json b/packages/svelte-query/tsconfig.legacy.json
new file mode 100644
index 0000000000..703c53b1c7
--- /dev/null
+++ b/packages/svelte-query/tsconfig.legacy.json
@@ -0,0 +1,7 @@
+{
+  "extends": "./tsconfig.json",
+  "compilerOptions": {
+    "outDir": "./dist-ts/legacy"
+  },
+  "include": ["src"]
+}
diff --git a/pnpm-lock.yaml b/pnpm-lock.yaml
index 829d54ddc9..4253e86331 100644
--- a/pnpm-lock.yaml
+++ b/pnpm-lock.yaml
@@ -3239,6 +3239,9 @@ importers:
       eslint-plugin-svelte:
         specifier: ^3.23.0
         version: 3.23.0(eslint@9.39.4(jiti@2.7.0)(supports-color@10.2.2))(svelte@5.57.1(@typescript-eslint/types@8.58.1))
+      npm-run-all2:
+        specifier: ^9.0.3
+        version: 9.0.3
       svelte:
         specifier: ^5.57.1
         version: 5.57.1(@typescript-eslint/types@8.58.1)
@@ -3276,6 +3279,9 @@ importers:
       eslint-plugin-svelte:
         specifier: ^3.23.0
         version: 3.23.0(eslint@9.39.4(jiti@2.7.0)(supports-color@10.2.2))(svelte@5.57.1(@typescript-eslint/types@8.58.1))
+      npm-run-all2:
+        specifier: ^9.0.3
+        version: 9.0.3
       svelte:
         specifier: ^5.57.1
         version: 5.57.1(@typescript-eslint/types@8.58.1)
@@ -3313,6 +3319,9 @@ importers:
       eslint-plugin-svelte:
         specifier: ^3.23.0
         version: 3.23.0(eslint@9.39.4(jiti@2.7.0)(supports-color@10.2.2))(svelte@5.57.1(@typescript-eslint/types@8.58.1))
+      npm-run-all2:
+        specifier: ^9.0.3
+        version: 9.0.3
       svelte:
         specifier: ^5.57.1
         version: 5.57.1(@typescript-eslint/types@8.58.1)