Core Changes

• BREAKING CHANGE!: bump default images.minimumCacheTTL from 1 min to 4 hours: #84105
• Feat: Add Model Context Protocol (MCP) server to Next.js dev server: #84100
• Upgrade React from d415fd3e-20250919 to 1eca9a27-20250922: #84093
• Turbopack: Remove the deprecated .turbo config object: #84109

Misc Changes

• docs: onRequestError request header type: #83988
• Turbopack: Improve persistent caching test case: #83205
• Turbopack: add more details to the graph panic: #84126
• docs: Cookies store access is async: #83987
• Bump Rust to nightly-2025-09-21: #83415
• Upgrade CodSpeed action and add analyzer benchmarks: #84135
• Turbopack: fix run_once when returning error: #84142
• [turbopack] Conditionally collect affecting sources: #83921
• Turbopack: slightly improve resolve_source_map_sources: #84147
• Turbopack: RawEcmascriptModule: #81806

Credits

Huge thanks to @icyJoseph, @sokra, @styfle, @gaojude, @mischnic, @lukesandberg, and @bgw for helping!