feat: allow resolve() to accept pathnames with query strings and hash fragments (#15458)

## Summary

Adds a `ResolvablePath` type that extends `Pathname` with optional
`?${string}` and `#${string}` suffixes, allowing `resolve()` to accept
pathnames with query strings and hash fragments.

- No runtime changes — `resolve_route()` already passes through `?` and
`#` correctly
- `Pathname` type is unchanged (still used for `page.url.pathname`)
- Existing `resolve()` behavior with route IDs and params is unaffected

## Motivation

Currently there is no way to use `goto()` with query strings or hash
fragments without either disabling the lint rule or bypassing
`resolve()`:

1. `resolve('/products?page=2')` fails type-checking (`Pathname` doesn't
include `?`)
2. `goto(resolve('/products') + '?page=2')` fails the
`svelte/no-navigation-without-resolve` lint rule (argument isn't a
`resolve()` call)

Per @teemingc's suggestion in #14750:
> "It should be possible to add a union type with a template string such
as `/my-route#${string}` and `/my-route?${string}`. This would continue
to keep the function type-safe."

This is a minimal type-only fix that doesn't conflict with #14756 (which
adds richer `{ hash, searchParams }` options).

## What this enables

```js
// All of these now type-check AND satisfy the lint rule:
goto(resolve('/products?page=2'));
goto(resolve(`/search?${params}`));
goto(resolve('/docs/intro#getting-started'));
```

## Test plan

- [x] `pnpm check` passes
- [x] `pnpm lint` passes
- [x] Existing tests pass (no runtime changes, only type widening)

Closes #14750

---------

Co-authored-by: Tee Ming <chewteeming01@gmail.com>

Author: BridgerB

.changeset/resolve-accept-query-hash.md

@@ -0,0 +1,5 @@
+---
+'@sveltejs/kit': patch
+---
+
+feat: allow `resolve()` to accept pathnames with a search string and/or hash

packages/kit/src/runtime/app/paths/client.js

@@ -1,4 +1,4 @@
-/** @import { Asset, RouteId, Pathname, ResolvedPathname } from '$app/types' */
+/** @import { Asset, RouteId, RouteIdWithSearchOrHash, Pathname, PathnameWithSearchOrHash, ResolvedPathname } from '$app/types' */
 /** @import { ResolveArgs } from './types.js' */
 import { base, assets, hash_routing } from './internal/client.js';
 import { resolve_route } from '../../../utils/routing.js';
@@ -47,7 +47,7 @@ const pathname_prefix = hash_routing ? '#' : '';
  * ```
  * @since 2.26
  *
- * @template {RouteId | Pathname} T
+ * @template {RouteIdWithSearchOrHash | PathnameWithSearchOrHash} T
  * @param {ResolveArgs<T>} args
  * @returns {ResolvedPathname}
  */

packages/kit/src/runtime/app/paths/public.d.ts

@@ -1,4 +1,4 @@
-import { RouteId, Pathname, ResolvedPathname } from '$app/types';
+import { RouteIdWithSearchOrHash, PathnameWithSearchOrHash, ResolvedPathname } from '$app/types';
 import { ResolveArgs } from './types.js';
 
 export { resolve, asset, match } from './client.js';
@@ -24,6 +24,6 @@ export let assets: '' | `https://${string}` | `http://${string}` | '/_svelte_kit
 /**
  * @deprecated Use [`resolve(...)`](https://svelte.dev/docs/kit/$app-paths#resolve) instead
  */
-export function resolveRoute<T extends RouteId | Pathname>(
+export function resolveRoute<T extends RouteIdWithSearchOrHash | PathnameWithSearchOrHash>(
 	...args: ResolveArgs<T>
 ): ResolvedPathname;

packages/kit/src/runtime/app/paths/types.d.ts

@@ -1,7 +1,23 @@
-import { Pathname, RouteId, RouteParams } from '$app/types';
+import {
+	PathnameWithSearchOrHash,
+	RouteId,
+	RouteIdWithSearchOrHash,
+	RouteParams
+} from '$app/types';
 
-export type ResolveArgs<T extends RouteId | Pathname> = T extends RouteId
-	? RouteParams<T> extends Record<string, never>
-		? [route: T]
-		: [route: T, params: RouteParams<T>]
-	: [route: T];
+type StripSearchOrHash<T extends string> = T extends `${infer Pathname}?${string}`
+	? Pathname
+	: T extends `${infer Pathname}#${string}`
+		? Pathname
+		: T;
+
+export type ResolveArgs<T extends RouteIdWithSearchOrHash | PathnameWithSearchOrHash> =
+	T extends RouteId
+		? RouteParams<T> extends Record<string, never>
+			? [route: T]
+			: [route: T, params: RouteParams<T>]
+		: StripSearchOrHash<T> extends infer U extends RouteId
+			? RouteParams<U> extends Record<string, never>
+				? [route: T]
+				: [route: T, params: RouteParams<U>]
+			: [route: T];

packages/kit/src/types/ambient.d.ts

@@ -104,6 +104,11 @@ declare module '$app/types' {
 	 */
 	export type RouteId = ReturnType<AppTypes['RouteId']>;
 
+	/**
+	 * `RouteId`, but possibly suffixed with a search string and/or hash.
+	 */
+	export type RouteIdWithSearchOrHash = RouteId | `${RouteId}?${string}` | `${RouteId}#${string}`;
+
 	/**
 	 * A utility for getting the parameters associated with a given route.
 	 */
@@ -123,6 +128,14 @@ declare module '$app/types' {
 	 */
 	export type Pathname = ReturnType<AppTypes['Pathname']>;
 
+	/**
+	 * `Pathname`, but possibly suffixed with a search string and/or hash.
+	 */
+	export type PathnameWithSearchOrHash =
+		| Pathname
+		| `${Pathname}?${string}`
+		| `${Pathname}#${string}`;
+
 	/**
 	 * `Pathname`, but possibly prefixed with a base path. Used for `page.url.pathname`.
 	 */

packages/kit/types/index.d.ts

@@ -3124,7 +3124,7 @@ declare module '$app/navigation' {
 }
 
 declare module '$app/paths' {
-	import type { RouteId, Pathname, ResolvedPathname, RouteParams, Asset } from '$app/types';
+	import type { RouteIdWithSearchOrHash, PathnameWithSearchOrHash, ResolvedPathname, RouteId, RouteParams, Asset, Pathname } from '$app/types';
 	/**
 	 * A string that matches [`config.kit.paths.base`](https://svelte.dev/docs/kit/configuration#paths).
 	 *
@@ -3146,14 +3146,25 @@ declare module '$app/paths' {
 	/**
 	 * @deprecated Use [`resolve(...)`](https://svelte.dev/docs/kit/$app-paths#resolve) instead
 	 */
-	export function resolveRoute<T extends RouteId | Pathname>(
+	export function resolveRoute<T extends RouteIdWithSearchOrHash | PathnameWithSearchOrHash>(
 		...args: ResolveArgs<T>
 	): ResolvedPathname;
-	type ResolveArgs<T extends RouteId | Pathname> = T extends RouteId
-		? RouteParams<T> extends Record<string, never>
-			? [route: T]
-			: [route: T, params: RouteParams<T>]
-		: [route: T];
+	type StripSearchOrHash<T extends string> = T extends `${infer Base}?${string}`
+		? Base
+		: T extends `${infer Base}#${string}`
+			? Base
+			: T;
+
+	type ResolveArgs<T extends RouteIdWithSearchOrHash | PathnameWithSearchOrHash> =
+		T extends RouteId
+			? RouteParams<T> extends Record<string, never>
+				? [route: T]
+				: [route: T, params: RouteParams<T>]
+			: StripSearchOrHash<T> extends infer U extends RouteId
+				? RouteParams<U> extends Record<string, never>
+					? [route: T]
+					: [route: T, params: RouteParams<U>]
+				: [route: T];
 	/**
 	 * Resolve the URL of an asset in your `static` directory, by prefixing it with [`config.kit.paths.assets`](https://svelte.dev/docs/kit/configuration#paths) if configured, or otherwise by prefixing it with the base path.
 	 *
@@ -3191,7 +3202,7 @@ declare module '$app/paths' {
 	 * @since 2.26
 	 *
 	 * */
-	export function resolve<T extends RouteId | Pathname>(...args: ResolveArgs<T>): ResolvedPathname;
+	export function resolve<T extends RouteIdWithSearchOrHash | PathnameWithSearchOrHash>(...args: ResolveArgs<T>): ResolvedPathname;
 	/**
 	 * Match a path or URL to a route ID and extracts any parameters.
 	 *
@@ -3577,6 +3588,11 @@ declare module '$app/types' {
 	 */
 	export type RouteId = ReturnType<AppTypes['RouteId']>;
 
+	/**
+	 * `RouteId`, but possibly suffixed with a search string and/or hash.
+	 */
+	export type RouteIdWithSearchOrHash = RouteId | `${RouteId}?${string}` | `${RouteId}#${string}`;
+
 	/**
 	 * A utility for getting the parameters associated with a given route.
 	 */
@@ -3596,6 +3612,14 @@ declare module '$app/types' {
 	 */
 	export type Pathname = ReturnType<AppTypes['Pathname']>;
 
+	/**
+	 * `Pathname`, but possibly suffixed with a search string and/or hash.
+	 */
+	export type PathnameWithSearchOrHash =
+		| Pathname
+		| `${Pathname}?${string}`
+		| `${Pathname}#${string}`;
+
 	/**
 	 * `Pathname`, but possibly prefixed with a base path. Used for `page.url.pathname`.
 	 */