I encountered this yesterday too. I don't use a package manager for my project since I'm using importmaps. I found that, while I had a biome.json file in the project root, whenever I opened a file that Biome wanted to process, thus loading it in my lsp, because my project doesn't have one of these files that the lsp uses as root_markers …

'package-lock.json', 'yarn.lock', 'pnpm-lock.yaml', 'bun.lockb', 'bun.lock'

… it traversed all the way up to my home dir where I do have a package-lock.json file and set this as my neovim root. I don't understand why biome.json isn't a root_marker value which would cover people using it for an LSP but with no package manager.

My solution was to edit the biome.lua lsp file to add biome.json to the root_markers value.

local root_markers = { 'biome.json', 'package-lock.json', 'yarn.lock', 'pnpm-lock.yaml', 'bun.lockb', 'bun.lock' }

Now neovim retains the project root as my root directory. However it might be prudent to create our own lsp/biome-mine.lua config file and copy the one from nvim-lspconfig (which I use but you didn't mention) to that file with my customization. Just in case a future update to nvim-lspconfig overwrites the customization.

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