fix: improve feat/transitions type

packages/next-usequerystate/src/defs.ts

@@ -1,10 +1,18 @@
 import { useRouter } from 'next/navigation.js' // https://github.com/47ng/next-usequerystate/discussions/352
+import type { TransitionStartFunction } from 'react'
 
 export type Router = ReturnType<typeof useRouter>
 
 export type HistoryOptions = 'replace' | 'push'
 
-export type Options = {
+// prettier-ignore
+type StartTransition<T> = T extends false
+  ? TransitionStartFunction
+  : T extends true
+    ? never
+    : TransitionStartFunction
+
+export type Options<Shallow = unknown> = {
   /**
    * How the query update affects page history
    *
@@ -29,7 +37,7 @@ export type Options = {
    * Setting it to `false` will trigger a network request to the server with
    * the updated querystring.
    */
-  shallow?: boolean
+  shallow?: Extract<Shallow | boolean, boolean>
 
   /**
    * Maximum amount of time (ms) to wait between updates of the URL query string.
@@ -48,8 +56,10 @@ export type Options = {
    * `React.useTransition()` hook.
    *
    * Using this will set the `shallow` setting to `false` automatically.
+   * As a result, you can't set both `shallow: true` and `startTransition`
+   * in the same Options object.
    */
-  startTransition?: React.TransitionStartFunction
+  startTransition?: StartTransition<Shallow>
 }
 
 export type Nullable<T> = {

packages/next-usequerystate/src/parsers.ts

@@ -15,7 +15,7 @@ export type ParserBuilder<T> = Required<Parser<T>> &
      * Note that you can override those options in individual calls to the
      * state updater function.
      */
-    withOptions<This>(this: This, options: Options): This
+    withOptions<This, Shallow>(this: This, options: Options<Shallow>): This
 
     /**
      * Specifying a default value makes the hook state non-nullable when the

packages/next-usequerystate/src/tests/parsers.test-d.ts

@@ -1,4 +1,4 @@
-import { expectType } from 'tsd'
+import { expectError, expectType } from 'tsd'
 import { parseAsString } from '../../dist'
 
 {
@@ -27,3 +27,50 @@ import { parseAsString } from '../../dist'
   expectType<string | null>(p.parse('foo'))
   expectType<string>(p.parseServerSide(undefined))
 }
+
+// Shallow / startTransition interaction
+{
+  type RSTF = React.TransitionStartFunction
+  type MaybeBool = boolean | undefined
+  type MaybeRSTF = RSTF | undefined
+
+  expectType<MaybeBool>(parseAsString.withOptions({}).shallow)
+  expectType<MaybeRSTF>(parseAsString.withOptions({}).startTransition)
+  expectType<MaybeBool>(parseAsString.withOptions({ shallow: true }).shallow)
+  expectType<MaybeRSTF>(
+    parseAsString.withOptions({ shallow: true }).startTransition
+  )
+  expectType<MaybeBool>(parseAsString.withOptions({ shallow: false }).shallow)
+  expectType<MaybeRSTF>(
+    parseAsString.withOptions({ shallow: false }).startTransition
+  )
+  expectType<MaybeBool>(
+    parseAsString.withOptions({ startTransition: () => {} }).shallow
+  )
+  expectType<MaybeRSTF>(
+    parseAsString.withOptions({ startTransition: () => {} }).startTransition
+  )
+  // Allowed
+  parseAsString.withOptions({
+    shallow: false,
+    startTransition: () => {}
+  })
+  // Not allowed
+  expectError(() => {
+    parseAsString.withOptions({
+      shallow: true,
+      startTransition: () => {}
+    })
+  })
+  expectError(() => {
+    parseAsString.withOptions({
+      shallow: {}
+    })
+  })
+
+  expectError(() => {
+    parseAsString.withOptions({
+      startTransition: {}
+    })
+  })
+}

packages/next-usequerystate/src/tests/useQueryState.test-d.ts

@@ -290,3 +290,17 @@ import {
   expectError(() => setFoo(() => undefined))
   expectError(() => setBar(() => undefined))
 }
+
+// Shallow & startTransition interaction
+{
+  const [, set] = useQueryState('foo')
+  set('ok', { shallow: true })
+  set('ok', { shallow: false })
+  set('ok', { startTransition: () => {} })
+  expectError(() => {
+    set('nope', {
+      shallow: true,
+      startTransition: () => {}
+    })
+  })
+}

packages/next-usequerystate/src/useQueryState.ts

@@ -18,14 +18,14 @@ export type UseQueryStateReturn<Parsed, Default> = [
   Default extends undefined
     ? Parsed | null // value can't be null if default is specified
     : Parsed,
-  (
+  <Shallow>(
     value:
       | null
       | Parsed
       | ((
           old: Default extends Parsed ? Parsed : Parsed | null
         ) => Parsed | null),
-    options?: Options
+    options?: Options<Shallow>
   ) => Promise<URLSearchParams>
 ]
 
@@ -206,7 +206,9 @@ export function useQueryState<T = string>(
     serialize = String,
     defaultValue = undefined,
     startTransition
-  }: Partial<UseQueryStateOptions<T>> & { defaultValue?: T } = {
+  }: Partial<UseQueryStateOptions<T>> & {
+    defaultValue?: T
+  } = {
     history: 'replace',
     scroll: false,
     shallow: true,