diff --git a/src/FsAutoComplete.Core/FsAutoComplete.Core.fsproj b/src/FsAutoComplete.Core/FsAutoComplete.Core.fsproj
index 81df0fe33..0c8f3994a 100644
--- a/src/FsAutoComplete.Core/FsAutoComplete.Core.fsproj
+++ b/src/FsAutoComplete.Core/FsAutoComplete.Core.fsproj
@@ -50,6 +50,7 @@
     <Compile Include="State.fs" />
     <Compile Include="CodeGeneration.fsi" />
     <Compile Include="CodeGeneration.fs" />
+    <Compile Include="UnionPatternMatchCaseGenerator.fsi" />
     <Compile Include="UnionPatternMatchCaseGenerator.fs" />
     <Compile Include="RecordStubGenerator.fs" />
     <Compile Include="AbstractClassStubGenerator.fs" />
diff --git a/src/FsAutoComplete.Core/UnionPatternMatchCaseGenerator.fsi b/src/FsAutoComplete.Core/UnionPatternMatchCaseGenerator.fsi
new file mode 100644
index 000000000..152063013
--- /dev/null
+++ b/src/FsAutoComplete.Core/UnionPatternMatchCaseGenerator.fsi
@@ -0,0 +1,36 @@
+/// Original code from VisualFSharpPowerTools project: https://github.com/fsprojects/VisualFSharpPowerTools/blob/master/src/FSharp.Editing/CodeGeneration/UnionPatternMatchCaseGenerator.fs
+module FsAutoComplete.UnionPatternMatchCaseGenerator
+
+open FSharp.Compiler.Syntax
+open FSharp.Compiler.Text
+open FSharp.Compiler.Symbols
+
+[<NoEquality; NoComparison>]
+type PatternMatchExpr =
+  {
+    /// Range of 'match x with' or 'function'
+    MatchWithOrFunctionRange: Range
+    /// The whole pattern match expression
+    Expr: SynExpr
+    Clauses: SynMatchClause list
+  }
+
+[<NoComparison>]
+type UnionMatchCasesInsertionParams =
+  { InsertionPos: Position
+    IndentColumn: int }
+
+val shouldGenerateUnionPatternMatchCases: patMatchExpr: PatternMatchExpr -> entity: FSharpEntity -> bool
+
+val tryFindUnionDefinitionFromPos:
+  codeGenService: ICodeGenerationService ->
+  pos: Position ->
+  document: Document ->
+    Async<(PatternMatchExpr * FSharpEntity * UnionMatchCasesInsertionParams) option>
+
+val formatMatchExpr:
+  insertionParams: UnionMatchCasesInsertionParams ->
+  caseDefaultValue: string ->
+  patMatchExpr: PatternMatchExpr ->
+  entity: FSharpEntity ->
+    string
diff --git a/src/FsAutoComplete/FsAutoComplete.fsproj b/src/FsAutoComplete/FsAutoComplete.fsproj
index 014cc81c9..fbc7f3054 100644
--- a/src/FsAutoComplete/FsAutoComplete.fsproj
+++ b/src/FsAutoComplete/FsAutoComplete.fsproj
@@ -29,12 +29,14 @@
     <Compile Include="CodeFixes/*.fsi" />
     <Compile Include="CodeFixes/*.fs" />
     <Compile Include="LspServers/IFSharpLspServer.fs" />
+    <Compile Include="LspServers/FSharpLspClient.fsi" />
     <Compile Include="LspServers/FSharpLspClient.fs" />
     <Compile Include="LspServers/Common.fs" />
     <Compile Include="LspServers/AdaptiveServerState.fsi" />
     <Compile Include="LspServers/AdaptiveServerState.fs" />
     <Compile Include="LspServers/AdaptiveFSharpLspServer.fsi" />
     <Compile Include="LspServers/AdaptiveFSharpLspServer.fs" />
+    <Compile Include="Parser.fsi" />
     <Compile Include="Parser.fs" />
     <Compile Include="Program.fs" />
     <None Include="FsAutoComplete.fsproj.paket.references" />
diff --git a/src/FsAutoComplete/LspServers/FSharpLspClient.fsi b/src/FsAutoComplete/LspServers/FSharpLspClient.fsi
new file mode 100644
index 000000000..984844d7c
--- /dev/null
+++ b/src/FsAutoComplete/LspServers/FSharpLspClient.fsi
@@ -0,0 +1,50 @@
+namespace FsAutoComplete.Lsp
+
+open Ionide.LanguageServerProtocol
+open Ionide.LanguageServerProtocol.Server
+open Ionide.LanguageServerProtocol.Types
+open FsAutoComplete.LspHelpers
+open System
+open IcedTasks
+
+type FSharpLspClient =
+  new: sendServerNotification: ClientNotificationSender * sendServerRequest: ClientRequestSender -> FSharpLspClient
+  inherit LspClient
+  member ClientCapabilities: ClientCapabilities option with get, set
+  override WindowShowMessage: ShowMessageParams -> Async<unit>
+  override WindowShowMessageRequest: ShowMessageRequestParams -> AsyncLspResult<MessageActionItem option>
+  override WindowLogMessage: LogMessageParams -> Async<unit>
+  override TelemetryEvent: Newtonsoft.Json.Linq.JToken -> Async<unit>
+  override ClientRegisterCapability: RegistrationParams -> AsyncLspResult<unit>
+  override ClientUnregisterCapability: UnregistrationParams -> AsyncLspResult<unit>
+  override WorkspaceWorkspaceFolders: unit -> AsyncLspResult<WorkspaceFolder array option>
+  override WorkspaceConfiguration: ConfigurationParams -> AsyncLspResult<Newtonsoft.Json.Linq.JToken array>
+  override WorkspaceApplyEdit: ApplyWorkspaceEditParams -> AsyncLspResult<ApplyWorkspaceEditResponse>
+  override WorkspaceSemanticTokensRefresh: unit -> Async<unit>
+  override TextDocumentPublishDiagnostics: PublishDiagnosticsParams -> Async<unit>
+  ///Custom notification for workspace/solution/project loading events
+  member NotifyWorkspace: p: PlainNotification -> Async<unit>
+  ///Custom notification for initial workspace peek
+  member NotifyWorkspacePeek: p: PlainNotification -> Async<unit>
+  member NotifyCancelledRequest: p: PlainNotification -> Async<unit>
+  member NotifyFileParsed: p: PlainNotification -> Async<unit>
+  member NotifyDocumentAnalyzed: p: DocumentAnalyzedNotification -> Async<unit>
+  member NotifyTestDetected: p: TestDetectedNotification -> Async<unit>
+  member CodeLensRefresh: unit -> Async<unit>
+  override WorkDoneProgressCreate: ProgressToken -> AsyncLspResult<unit>
+  override Progress: ProgressToken * 'Progress -> Async<unit>
+
+type ServerProgressReport =
+  new: lspClient: FSharpLspClient * ?token: ProgressToken -> ServerProgressReport
+  member Token: ProgressToken
+  member Begin: title: string * ?cancellable: bool * ?message: string * ?percentage: uint -> CancellableTask<unit>
+  member Report: ?cancellable: bool * ?message: string * ?percentage: uint -> CancellableTask<unit>
+  member End: ?message: string -> CancellableTask<unit>
+  interface IAsyncDisposable
+  interface IDisposable
+
+/// <summary>listener for the the events generated from the fsc ActivitySource</summary>
+type ProgressListener =
+  new: lspClient: FSharpLspClient * traceNamespace: string array -> ProgressListener
+  interface IDisposable
+  interface IAsyncDisposable
diff --git a/src/FsAutoComplete/Parser.fs b/src/FsAutoComplete/Parser.fs
index c7b0736b5..0ad58284b 100644
--- a/src/FsAutoComplete/Parser.fs
+++ b/src/FsAutoComplete/Parser.fs
@@ -30,24 +30,18 @@ module Parser =
       Start: FSharp.Compiler.Text.pos
       End: FSharp.Compiler.Text.pos }
 
-  let private setArity arity (o: #Option) =
+  let setArity arity (o: #Option) =
     o.Arity <- arity
     o
 
   /// set option to expect no arguments (e.g a flag-style argument: `--verbose`)
-  let inline private zero x = setArity ArgumentArity.Zero x
+  let inline zero x = setArity ArgumentArity.Zero x
   /// set option to expect one argument (e.g a single value: `--foo bar)
-  let inline private one x = setArity ArgumentArity.ExactlyOne x
+  let inline one x = setArity ArgumentArity.ExactlyOne x
 
   /// set option to expect multiple arguments
   /// (e.g a list of values: `--foo bar baz` or `--foo bar --foo baz` depending on the style)
-  let inline private many x = setArity ArgumentArity.OneOrMore x
-
-  /// set option to allow multiple arguments per use of the option flag
-  /// (e.g. `--foo bar baz` is equivalent to `--foo bar --foo baz`)
-  let inline private multipleArgs (x: #Option) =
-    x.AllowMultipleArgumentsPerToken <- true
-    x
+  let inline many x = setArity ArgumentArity.OneOrMore x
 
   let verboseOption =
     Option<bool>([| "--verbose"; "-v"; "--debug" |], "Enable verbose logging. This is equivalent to --log-level debug.")
diff --git a/src/FsAutoComplete/Parser.fsi b/src/FsAutoComplete/Parser.fsi
new file mode 100644
index 000000000..8a6d642e3
--- /dev/null
+++ b/src/FsAutoComplete/Parser.fsi
@@ -0,0 +1,6 @@
+namespace FsAutoComplete
+
+open System.CommandLine.Parsing
+
+module Parser =
+  val parser: Parser