Narrow excess-property acceptance for query init types in swr-openapi

.changeset/ripe-singers-bow.md

@@ -0,0 +1,5 @@
+---
+"swr-openapi": patch
+---
+
+Narrow excess-property acceptance for query init types

docs/swr-openapi/use-infinite.md

@@ -88,6 +88,33 @@ useInfinite("/something", (pageIndex, previousPageData) => {
 });
 ```
 
+### Enforcing exact param shapes
+
+When returning an object from the `getInit` loader, TypeScript may not always perform excess property checks on the inline object literal. If you want the compiler to reject extra keys in `params.query`/`params.path`, use either of these patterns:
+
+```ts
+import type { TypesForRequest } from "swr-openapi";
+import type { paths } from "./my-schema";
+
+// Option 1: typed variable
+type FindByStatus = TypesForRequest<paths, "get", "/pet/findByStatus">;
+const init: FindByStatus["Init"] = {
+  params: { query: { status: "available" } },
+  // extra properties here will be rejected by TS
+};
+useInfinite("/pet/findByStatus", () => init);
+
+// Option 2: satisfies
+useInfinite(
+  "/pet/findByStatus",
+  () =>
+    ({
+      params: { query: { status: "available" } },
+      // extra properties here will be rejected by TS
+    }) satisfies TypesForRequest<paths, "get", "/pet/findByStatus">["Init"]
+);
+```
+
 ### Using cursors
 
 ```ts
@@ -147,7 +174,6 @@ function useInfinite(path, getInit, config) {
 }
 ```
 
-
 [oai-fetch-options]: https://openapi-ts.pages.dev/openapi-fetch/api#fetch-options
 [swr-api]: https://swr.vercel.app/docs/api
 [swr-infinite]: https://swr.vercel.app/docs/pagination#useswrinfinite

packages/swr-openapi/src/__test__/types.test-d.ts

@@ -39,6 +39,46 @@ const useMutate = createMutateHook(
 const mutate = useMutate();
 
 describe("types", () => {
+  describe("excess property checks", () => {
+    describe("useQuery", () => {
+      it("rejects extra properties in query params", () => {
+        useQuery("/pet/findByStatus", {
+          params: {
+            query: {
+              status: "available",
+              // @ts-expect-error extra property should be rejected
+              invalid_property: "nope",
+            },
+          },
+        });
+      });
+
+      it("rejects extra properties in path params", () => {
+        useQuery("/pet/{petId}", {
+          params: {
+            path: {
+              petId: 5,
+              // @ts-expect-error extra property should be rejected
+              invalid_path_param: "nope",
+            },
+          },
+        });
+      });
+
+      it("rejects extra properties in header params", () => {
+        useQuery("/pet/findByStatus", {
+          params: {
+            header: {
+              "X-Example": "test",
+              // @ts-expect-error extra property should be rejected
+              "Invalid-Header": "nope",
+            },
+          },
+        });
+      });
+    });
+  });
+
   describe("key types", () => {
     describe("useQuery", () => {
       it("accepts config", () => {

packages/swr-openapi/src/query-base.ts

@@ -17,13 +17,14 @@ export function configureBaseQueryHook(useHook: SWRHook) {
     return function useQuery<
       Path extends PathsWithMethod<Paths, "get">,
       R extends TypesForGetRequest<Paths, Path>,
-      Init extends R["Init"],
       Data extends R["Data"],
       Error extends R["Error"] | FetcherError,
       Config extends R["SWRConfig"],
     >(
       path: Path,
-      ...[init, config]: RequiredKeysOf<Init> extends never ? [(Init | null)?, Config?] : [Init | null, Config?]
+      ...[init, config]: RequiredKeysOf<R["Init"]> extends never
+        ? [(R["Init"] | null)?, Config?]
+        : [R["Init"] | null, Config?]
     ) {
       useDebugValue(`${prefix} - ${path as string}`);