fix(storage): restore makePersisted type inference for input signal

.changeset/makepersisted-type-inference-fix.md

@@ -0,0 +1,5 @@
+---
+"@solid-primitives/storage": patch
+---
+
+fix: restore `makePersisted` generic type inference under TypeScript 5+/7. Calling `makePersisted(createSignal("hello"), { name, storage: localStorage })` previously fell back to `T = unknown` and errored with `TS2769`. The public overloads now extract `T` from `S` via `SignalType<S>` (as in 4.3.5).

packages/storage/src/persisted.ts

@@ -70,6 +70,11 @@ export type PersistenceOptions<T, O extends Record<string, any> | undefined> = {
       storageOptions?: O;
     });
 
+export type SignalInput = Signal<any> | [Store<any>, SetStoreFunction<any>];
+
+export type SignalType<S extends SignalInput> =
+  S extends Signal<infer T> ? T : S extends [Store<infer T>, SetStoreFunction<infer T>] ? T : never;
+
 export type PersistedState<S> = S & { 2: Promise<string> | string | null };
 
 /**
@@ -92,19 +97,18 @@ export type PersistedState<S> = S & { 2: Promise<string> | string | null };
  * @param {PersistenceOptions<T, O>} options - The options for persistence.
  * @returns {PersistedState<T>} - The persisted signal or store.
  */
-export function makePersisted<T, S extends Signal<T> | [Store<T>, SetStoreFunction<T>]>(
+export function makePersisted<S extends SignalInput>(
   signal: S,
-  options?: PersistenceOptions<T, undefined>,
+  options?: PersistenceOptions<SignalType<S>, undefined>,
+): PersistedState<S>;
+export function makePersisted<S extends SignalInput, O extends Record<string, any>>(
+  signal: S,
+  options: PersistenceOptions<SignalType<S>, O>,
 ): PersistedState<S>;
 export function makePersisted<
-  T,
-  S extends Signal<T> | [Store<T>, SetStoreFunction<T>],
-  O extends Record<string, any>,
->(signal: S, options: PersistenceOptions<T, O>): PersistedState<S>;
-export function makePersisted<
-  T,
-  S extends Signal<T> | [Store<T>, SetStoreFunction<T>],
+  S extends SignalInput,
   O extends Record<string, any> | undefined,
+  T = SignalType<S>,
 >(
   signal: S,
   options: PersistenceOptions<T, O> = {} as PersistenceOptions<T, O>,

packages/storage/test/persisted.test.ts

@@ -141,4 +141,16 @@ describe("makePersisted", () => {
     });
     expect(init).toBe(promise);
   });
+  it("infers the signal value type from the input without explicit annotations", () => {
+    // Regression test for solid-primitives#1000: under TypeScript 5+/7 the
+    // overloads previously defaulted T to `unknown` instead of inferring it
+    // from the input signal/store, breaking inference at the call site.
+    const [thing, setThing] = makePersisted(createSignal("hello"), {
+      name: "thing",
+      storage: mockStorage,
+    });
+    const _a: string = thing();
+    const _b: string = setThing("world");
+    expect(thing()).toBe("world");
+  });
 });