Language Server — LSP scaffold + diagnostics

[TomProkop]

Summary

LSP server providing real-time diagnostics and navigation for Dataverse solution XML files in VS Code.

Scope

LSP server scaffold

• New project TALXIS.Platform.Metadata.LanguageServer
• LSP framework (OmniSharp or Microsoft.VisualStudio.LanguageServer.Protocol)
• textDocument/didOpen, textDocument/didChange, textDocument/didClose
• Workspace load at startup (via InMemoryContext)

Diagnostics

• XSD validation errors → LSP diagnostics with source location
• Duplicate GUID detection
• Dangling references (control → non-existent attribute) → warning
• Model-load errors from Workspace.LoadErrors
• Leverage SourceLocation from core model for precise positions (line, column)

Completions

• Entity logical names in lookups and references
• Attribute logical names in datafieldname attributes
• FormId / ViewId reference completions
• OptionSet values
• ClassId completions for control types

Go-to-definition

• datafieldname → attribute definition in Entity.xml
• Lookup reference → target entity
• FormId reference → form file
• OptionSet reference → definition

File watching + incremental reload

• workspace/didChangeWatchedFiles handler
• Incremental reload (only changed files)
• InMemoryContext for fast model update
• Invalidate diagnostics for changed files

VS Code extension

• Extension manifest — language ID for .xml in Declarations/ context
• LSP client configuration
• Activation on Solution.xml detection

Depends on

• IWorkspaceContext interface + implementations #60 (IWorkspaceContext — needs InMemoryContext)

Ref: docs/roadmap.md Milestone 7, docs/runtime-architecture.md.