fix(@tanstack/query-core): skip SSE endpoints in createMutationOptions

[Copilot]

createMutationOptions was missing the hasOperationSse guard that createQueryOptions and createUseQuery already have, causing SSE POST endpoints to generate a broken mutationFn that destructures { data } from ServerSentEventsResult (which has stream, not data).

Changes

• mutationOptions.ts: Add early-return guard if (hasOperationSse({ operation })) return — mirrors the existing pattern in queryOptions.ts and useQuery.ts
• specs/3.1.x/sse-post.yaml: Minimal spec with a POST SSE endpoint + a GET JSON endpoint to drive the new test
• 3.1.x.test.ts + snapshots: Test case confirming the SSE POST endpoint produces no entry in @tanstack/react-query.gen.ts while the GET endpoint still generates queryOptions normally

// Before — generated broken mutation for POST /events/subscribe (SSE):
export const subscribeToEventStreamMutation = (options?) => ({
  mutationFn: async (fnOptions) => {
    const { data } = await subscribeToEventStream({ ... }); // TS error: no 'data' on ServerSentEventsResult
    return data;
  },
});

// After — SSE endpoint is silently skipped, no mutation emitted

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Original prompt

---

This section details on the original issue you should resolve

<issue_title>React Query generates broken mutation for SSE endpoints — missing hasOperationSse guard</issue_title>
<issue_description>## Description

The @tanstack/react-query plugin generates a mutation function for SSE endpoints that destructures { data } from the SDK call. However, SSE endpoints return ServerSentEventsResult which has a stream property, not data. This produces a TypeScript error.

Root Cause

In createMutationOptions, the generated mutation function assumes the SDK call returns { data }:

// Generated @tanstack/react-query.gen.ts
export const subscribeToEventStreamMutation = (options?) => ({
  mutationFn: async (localOptions) => {
    const { data } = await subscribeToEventStream({ ... }); // ← TS error: no 'data' on ServerSentEventsResult
    return data;
  },
});

But subscribeToEventStream returns ServerSentEventsResult which is:

type ServerSentEventsResult<TData = unknown> = {
  stream: AsyncGenerator<...>;  // not 'data'
};

The query-related handlers (createQueryOptions, createUseQuery) already skip SSE endpoints with:

if (hasOperationSse({ operation })) return;

But createMutationOptions is missing this guard.

Expected Behavior

createMutationOptions should skip SSE endpoints, consistent with the other handlers:

const createMutationOptions = ({ operation, plugin }) => {
  if (hasOperationSse({ operation })) return; // ← missing guard
  // ...
};

Versions

• @hey-api/openapi-ts: 0.92.3
• @tanstack/react-query plugin</issue_description>

Comments on the Issue (you are @copilot in this section)

• Fixes React Query generates broken mutation for SSE endpoints — missing hasOperationSse guard #3465

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Project	Deployment	Actions	Updated (UTC)
hey-api-docs	Ready	Preview, Comment	Feb 26, 2026 11:35pm

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