#8425 Experimental ReScript Language Server in OCaml

- Move Io, Chan, and listen infrastructure to server.ml - Simplify on_request to take a packed request directly - Add basic hover response with markdown content - Rename public executable to rescript-language-server

- Add parse_implementation_from_source to parsing/print engine types and all engine implementations, enabling parsing from a string source rather than a filename - Use parse_implementation_from_source in CompletionFrontEnd - Rename package from rescript-lsp to rescript-language-server - Refactor LSP server with typed state, document store, and diagnostics - Add hover support via completion backend integration

Move LSP modules under lsp/src/ with a thin lsp/bin/ entry point, add a configuration module, and introduce a tests/lsp_tests workspace exercising hover end-to-end.

Splits Commands.ml into a pure layer that returns OCaml values (option, list, typed records like Protocol.hover, Protocol.signatureHelp, Protocol.completionItem) and a new analysis/src/Cli.ml that does the stringify-and-print step. analysis/bin/main.ml now dispatches to Cli.*, while the LSP server consumes Commands.* directly.

Makes the parsers accept source strings: res_driver gains parse_interface_from_source alongside the existing parse_implementation_from_source

- Rename Helper module to Client - Move expected output files into workspace directories - Improve request log format to show file path:line:col - Simplify hover.ml by removing intermediate result binding - Disable in-source compilation for basic-workspace

Parse ReScript compiler logs into LSP diagnostics and keep diagnostic state in the language server so stale entries can be cleared when logs change. Read build roots from .sourcedirs.json to support monorepos and refresh diagnostics across all compiler logs instead of only the changed watch path.

Register dynamic workspace/didChangeWatchedFiles watchers after the client sends initialized, and add server-side request/response tracking so client responses to server requests no longer crash the input loop.

Tighten document store errors, thread the Eio environment through server state, update hover handling to use the current analysis API, and extend LSP tests to initialize the server before running workspace requests.

ppx_expect uses Jane Street-style opam versions like v0.17.2, not 0.17.2

Keep the language server library independent from Eio_main by exposing a listen function that accepts input, output, and filesystem handles. Store only the filesystem handle in LSP state and remove the unused environment from the server record.

Advertise and implement the main language server capabilities using the existing analysis commands, including completion, signature help, definition, references, document symbols, code actions, code lenses, inlay hints, semantic tokens, rename, and formatting.

Rework diagnostics so compiler log diagnostics are treated as build snapshots, stale entries are cleared, and syntax diagnostics from the current in-memory document are appended on change. Also make document symbols source-based so the LSP can serve open documents without reading from disk.

Track initialize, running, and shutdown states in the LSP server loop. Reject requests before initialization with ServerNotInitialized, reject requests after shutdown with InvalidRequest, and allow exit notifications to terminate with the correct status code.

Also make unsupported requests and notifications explicit in the language server handlers.

This reverts commit bbcb7b9388c5a577fa1fa71f5feabe881db1f978.

- Add package to server state - Add to_yojson in state

Resolve the workspace root from initialize params, initialize analysis state only after the server is initialized, and keep the active package in the initialized server state.

Populate analysis package caches for the workspace and dependencies. Resolve document requests against the package whose root best matches the document path, so nested package workspaces use the correct package metadata.

Pull workspace configuration from the client and decode it into typed server settings for hover, code lens, inlay hints, and signature help behavior.

Route server-initiated request responses through an on_response handler so configuration updates do not block the LSP input loop

Add code actions and execute commands for opening compiled output, creating interface files, switching between implementation/interface files, and dumping server state. Centralize filesystem access through option-based Eio helpers so LSP paths can be checked without raising.

DocumentSymbol.children is optional, so only set it when a symbol has nested entries. This avoids serializing leaf symbols with an empty children array.

Prefer package-manager installs under the active workspace when resolving dependencies, including Deno and pnpm node_modules layouts.

Keep Runtime_package.path as a compiler-development fallback so editor navigation does not jump from user projects into the server checkout.

Publish syntax error diagnostic on open document

Track compiler diagnostics, compiler syntax diagnostics, and open-document syntax diagnostics independently so each source can be refreshed according to its own lifetime.

A syntax-only compiler log is an incomplete build snapshot, so keep existing type diagnostics until the next complete compiler snapshot or successful empty log. Open documents continue to use in-memory syntax diagnostics, while closed documents can fall back to compiler syntax diagnostics.

Read diagnostics from the compiler-log roots recorded in .sourcedirs.json so opening a document can publish the last known compiler diagnostics even when the compiler is not currently running.

Keep the root lib/bs/.compiler.log fallback only for older or partial builds without sourcedirs metadata, and document the diagnostic behavior and release notes.

Do not push open-buffer syntax diagnostics through textDocument/publishDiagnostics on didChange. They are already available through textDocument/diagnostic.

Keep the changed URI force-published so any stale pushed syntax diagnostics are cleared when the filtered diagnostic set is empty.

file://name.res#LX,Y

Works in VSCode and Zed!!

Merge all diagnostic sources when serving requests and serializing state. Ignore partial compiler logs until #Done, then publish the completed snapshot and refresh pull diagnostics so clients clear resolved warnings without flickering.