Summary

Release v4.12.20 contains two targeted bug fixes: preservation of the base path when mounting a route() app, and a TypeScript typing change that widens jsx/jsxFn children to Child[]. This release also includes a first-time contributor.

Key Points

• fix(route): mounted route() apps now preserve their base path (fix merged in #4942).
• fix(jsx): jsx and jsxFn children types widened to Child[] to relax TypeScript constraints (fix merged in #4947).
• contributor: @ashunar0 made their first contribution in #4947.

Impact & Actions for Engineers

• Mounting behavior: If you mount a route() app, expect the base path to be preserved. Review any custom mounting logic or middleware that assumed the previous behavior.
• TypeScript: The jsx/jsxFn typing change is a widening (less strict). If you relied on the prior narrower types, verify your components compile and adjust custom type assertions if needed.
• Upgrade: Update to v4.12.20 to pick up these fixes. Run your test suite focusing on routing mount points and any JSX component type interactions.

Reference

• Full changelog range: v4.12.19...v4.12.20
• Release published: 2026-05-19T10:41:30.000Z