docs: project scope, roadmap, instructions

Author: jokeyrhyme

README.md

@@ -2,8 +2,71 @@
 
 Language Server Protocol implementation for nushell
 
+## status
+
+- the official [nushell](http://www.nushell.sh/) project
+  (from version [0.79](https://www.nushell.sh/blog/2023-04-25-nushell_0_79.html), onwards)
+  is where the language-specific smarts are implemented,
+  e.g. `nu --ide-hover`
+
+- the official [extension for Visual Studio Code](https://github.com/nushell/vscode-nushell-lang)
+  is an IDE-specific wrapper around `nu --ide-hover`, etc
+
+- similarly, `nuls` (this project) is a wrapper around the `nu --ide-hover`, etc,
+  but implements the [Language Server Protocol](https://microsoft.github.io/language-server-protocol/)
+
+## project scope
+
+- `nuls` aims to have all the same LSP-powered features as the Visual Studio Code extension,
+  but working in any IDE/editor that can connect to a language server,
+  e.g. [`helix`](https://helix-editor.com/), [`neovim`](https://neovim.io/), etc
+
+- for now, please keep feature requests and bug reports focused on this goal
+
+- functionality that is not supported by upstream `nu --ide-...` is out-of-scope
+
+- functionality in `vscode-nushell-lang` that goes beyond LSP is out-of-scope
+
+## roadmap
+
+(in no particular order, and open to suggestions)
+
+- [x] [textDocument/hover](https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification/#textDocument_hover) -> `nu --ide-hover`
+- [x] [textDocument/completion](https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification/#textDocument_completion) -> `nu --ide-complete`
+- [x] [textDocument/definition](https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification/#textDocument_definition) -> `nu --ide-goto-def`
+      (navigates to file containing the definition)
+- [ ] [textDocument/definition](https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification/#textDocument_definition) -> `nu --ide-goto-def`
+      (navigates to precise row and column for the definition)
+- [ ] [textDocument/inlayHint](https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification/#textDocument_inlayHint) -> `nu --ide-check`
+- [ ] [textDocument/publishDiagnostics](https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification/#textDocument_publishDiagnostics) -> `nu --ide-check`
+- [ ] [textDocument/didOpen](https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification/#textDocument_synchronization), etc
+- [ ] [textDocument/formatting](https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification/#textDocument_formatting) -> [`nufmt`](https://github.com/nushell/nufmt)
+- [ ] raise a PR for `vscode-nushell-lang` to replace its wrapper/glue code with `nuls`
+
+## getting started
+
+### `helix` (23.05)
+
+- (optional) follow https://github.com/nushell/tree-sitter-nu/blob/main/installation/helix.md for the treesitter grammar
+
+- add the following to your languages.toml:
+
+  ```
+  [[language]]
+  name = "nu"
+  auto-format = false
+  comment-token = "#"
+  file-types = [ "nu" ]
+  language-server = { command = "path/to/nuls" }
+  roots = []
+  scope = "source.nu"
+  shebangs = ["nu"]
+  ```
+
 ## see also
 
 - http://www.nushell.sh/
 - https://github.com/nushell/vscode-nushell-lang
+- https://github.com/nushell/vscode-nushell-lang/issues/117
 - https://github.com/nushell/tree-sitter-nu
+- https://microsoft.github.io/language-server-protocol/