next.js

d884398d - feat(build): optimize filterUniqueParamsCombinations to generate sub-combinations (#81321)

feat(build): optimize filterUniqueParamsCombinations to generate sub-combinations (#81321) ### What? Optimizes the `generateParamPrefixCombinations` function (previously `filterUniqueRootParamsCombinations`) to generate all unique sub-combinations of route parameters while ensuring partial shells include complete sets of root parameters. ### Why? The previous implementation only generated combinations at the root parameter level, which was insufficient for PPR (Partial Prerendering) shells. PPR needs all possible prefix combinations of route parameters to create effective shells for nested routes. For example, for a route `/[lang]/[region]/[slug]`, we need shells for: - `/[lang]/[region]` (complete root params) - `/[lang]/[region]/[slug]` (full route) Without proper sub-combinations, nested routes couldn't benefit from PPR shell optimization, leading to performance degradation. ### How? - Renamed `filterUniqueRootParamsCombinations` to `generateParamPrefixCombinations` to better reflect its expanded functionality - Added logic to generate all prefix combinations of route parameters, not just root-level combinations - Implemented root parameter validation to ensure partial shells only include complete sets of root parameters - Added comprehensive test coverage for edge cases including undefined parameters, missing keys, and parameter collisions - Optimized the algorithm to skip invalid combinations early when root parameters are incomplete The function now generates prefix combinations systematically while maintaining backward compatibility and preventing invalid partial routes. NAR-159 --------- Co-authored-by: Hendrik Liebau <mail@hendrik-liebau.de>