Which middleware is the feature for?

@hono/zod-openapi

What is the feature you are proposing?

Accept openapi: '3.2.0' documents in getOpenAPIDocument().

OpenAPI 3.2.0 (released 2025-09-19) added hierarchical tags (parent, summary, kind on the Tag Object), itemSchema for streaming media types, and the QUERY method. Until this week the blocker was the underlying generator, but @asteasolutions/zod-to-openapi shipped 3.2 support in v9.0.0 (2026-07-14, see asteasolutions/zod-to-openapi#385). @hono/zod-openapi@1.5.1 still pins @asteasolutions/zod-to-openapi@^8.5.0, so 3.2 is now one engine bump away rather than blocked.

Is adopting the v9 engine on the roadmap, and is there a rough timeline? Happy to help test: we run a 164-operation production spec on @hono/zod-openapi and would exercise the tag parent/kind hierarchy immediately (it replaces the x-tagGroups extension for sidebar grouping, which relates to #720).