Add the F# Interactive window on the JSON-RPC protocol

.claude/rules/CcrOptout.md

@@ -0,0 +1,6 @@
+---
+paths:
+  - "**"
+---
+
+@../../.github/instructions/CcrOptout.instructions.md

VisualFSharp.slnx

@@ -108,6 +108,9 @@
     <Project Path="vsintegration/src/FSharp.Editor/FSharp.Editor.fsproj">
       <BuildType Solution="Proto|*" Project="Release" />
     </Project>
+    <Project Path="vsintegration/src/FSharp.Interactive.Window/FSharp.Interactive.Window.fsproj">
+      <BuildType Solution="Proto|*" Project="Release" />
+    </Project>
     <Project Path="vsintegration/src/FSharp.ProjectSystem.PropertyPages/FSharp.ProjectSystem.PropertyPages.vbproj">
       <BuildType Solution="Proto|*" Project="Release" />
     </Project>

docs/release-notes/.VisualStudio/18.vNext.md

@@ -1,6 +1,7 @@
 ### Added
 
 * Code-fixes for FS3888 (compiler-semantic attribute on the `.fs` but not the `.fsi`): copy the attribute into the `.fsi`, or remove it from the `.fs`. ([Issue #19560](https://github.com/dotnet/fsharp/issues/19560), [PR #19880](https://github.com/dotnet/fsharp/pull/19880))
+* The F# Interactive window is rebuilt on the Interactive Window package and talks to `dotnet fsi` over its JSON-RPC server mode: the input and output are coloured, Enter submits only a complete interaction, diagnostics carry positions in the submitted file, and the session starts in the solution folder, so the SDK that `global.json` names supplies the compiler. ([PR #20565](https://github.com/dotnet/fsharp/pull/20565))
 * Expand `<inheritdoc/>` in IDE tooltips, completion, and signature help, inheriting XML documentation from base classes, interfaces, overridden members, and constructors. ([Issue #19175](https://github.com/dotnet/fsharp/issues/19175), [PR #19188](https://github.com/dotnet/fsharp/pull/19188))
 
 ### Fixed

eng/Packages.props

@@ -70,6 +70,9 @@
     <PackageVersion Include="Microsoft.VisualStudio.Extensibility.Sdk" Version="17.13.39620" />
     <PackageVersion Include="Microsoft.VisualStudio.Extensibility.Testing.SourceGenerator" Version="$(MicrosoftVisualStudioExtensibilityTestingVersion)" />
     <PackageVersion Include="Microsoft.VisualStudio.Extensibility.Testing.Xunit" Version="$(MicrosoftVisualStudioExtensibilityTestingVersion)" />
+    <!-- The REPL window itself. Visual Studio installs it as a prerequisite component, and both
+         C# Interactive and Python Interactive are built on it. -->
+    <PackageVersion Include="Microsoft.VisualStudio.InteractiveWindow" Version="4.0.0" />
     <PackageVersion Include="Microsoft.VisualStudio.Language.Intellisense" Version="$(VisualStudioEditorPackagesVersion)" />
     <PackageVersion Include="Microsoft.VisualStudio.Language.StandardClassification" Version="$(VisualStudioEditorPackagesVersion)" />
     <!-- Pinned to 17.13.9 (not the projects' 17.13.6-preview floor) because Protocol.Internal 17.13.9,
@@ -88,6 +91,11 @@
     <PackageVersion Include="Microsoft.VisualStudio.ProjectSystem.Managed" Version="2.3.6152103" />
     <PackageVersion Include="Microsoft.VisualStudio.ProjectSystem.Query" Version="17.13.66" />
     <PackageVersion Include="Microsoft.VisualStudio.Shell.Design" Version="18.9.493" />
+    <!-- Supplies AsyncPackage and the tool window base types. Pinned to the version the Roslyn
+         IDE packages already resolve here transitively. -->
+    <PackageVersion Include="Microsoft.VisualStudio.Shell.15.0" Version="18.9.918" />
+    <!-- Hosts the interactive window as a Visual Studio tool window. -->
+    <PackageVersion Include="Microsoft.VisualStudio.VsInteractiveWindow" Version="4.0.0" />
     <PackageVersion Include="Microsoft.VisualStudio.Shell.Immutable.10.0" Version="10.0.30319" />
     <PackageVersion Include="Microsoft.VisualStudio.Shell.Immutable.11.0" Version="11.0.50727" />
     <PackageVersion Include="Microsoft.VisualStudio.Shell.Immutable.15.0" Version="15.0.25123-Dev15Preview" />

src/fsi/interactiveProtocol.fs

@@ -38,6 +38,11 @@ module Methods =
     [<Literal>]
     let Shutdown = "fsi/shutdown"
 
+/// How a host asks for this protocol, at the point where there is no protocol yet to ask over.
+module CommandLine =
+    [<Literal>]
+    let ServerOption = "--fsi-server-jsonrpc:"
+
 [<CLIMutable>]
 type InitializeResult =
     {
@@ -67,7 +72,7 @@ type ExecuteRequest =
         /// with <c>startLine</c> this makes diagnostics point at the user's own source rather than
         /// at a position within the submission.
         /// </summary>
-        sourcePath: string
+        sourcePath: string | null
 
         startLine: System.Nullable<int>
     }
@@ -78,7 +83,7 @@ type ExecuteFileRequest = { path: string }
 [<CLIMutable>]
 type SetPathsRequest =
     {
-        includePaths: string[]
+        includePaths: string[] | null
         workingDirectory: string
     }
 
@@ -123,8 +128,8 @@ type ExecutionResult =
         success: bool
 
         cancelled: bool
-        diagnostics: DiagnosticInfo[]
-        ``exception``: ExceptionInfo
+        diagnostics: DiagnosticInfo[] | null
+        ``exception``: ExceptionInfo | null
         values: ValueInfo[]
 
         /// Reported after every interaction so that the host can keep its own view of the session

tests/FSharp.Compiler.Interactive.Server.Tests/FSharp.Compiler.Interactive.Server.Tests.fsproj

@@ -24,6 +24,19 @@
     <Compile Include="$(FSharpSourcesRoot)\fsi\interactiveProtocol.fs">
       <Link>interactiveProtocol.fs</Link>
     </Compile>
+    <!-- The submission rule belongs to the Visual Studio window, but depends only on a lexer, which
+         the window is handed by the editor: the two are exercised together here rather than needing
+         a Windows-only test host. -->
+    <Compile Include="$(MSBuildThisFileDirectory)..\..\vsintegration\src\FSharp.Interactive.Window\LexicalScanning.fs">
+      <Link>LexicalScanning.fs</Link>
+    </Compile>
+    <Compile Include="$(MSBuildThisFileDirectory)..\..\vsintegration\src\FSharp.Editor\Commands\InteractiveLexicalScanner.fs">
+      <Link>InteractiveLexicalScanner.fs</Link>
+    </Compile>
+    <Compile Include="$(MSBuildThisFileDirectory)..\..\vsintegration\src\FSharp.Interactive.Window\SubmissionAnalysis.fs">
+      <Link>SubmissionAnalysis.fs</Link>
+    </Compile>
+    <Compile Include="SubmissionAnalysisTests.fs" />
     <Compile Include="FsiServerHarness.fs" />
     <Compile Include="FsiJsonRpcServerTests.fs" />
   </ItemGroup>

tests/FSharp.Compiler.Interactive.Server.Tests/FsiJsonRpcServerTests.fs

@@ -667,6 +667,24 @@ let ``the session exits when its host process exits`` () =
 
     Assert.True(session.WaitForExit 30_000, "the session outlived its host process")
 
+[<Fact>]
+let ``the last owner named on the command line is the one that counts`` () =
+    // A host puts its own switches after the user's arguments to keep them from naming another owner,
+    // which holds only if the last occurrence wins.
+    use earlier = new FsiServerHarness()
+
+    use session =
+        new FsiServerHarness(
+            serverSwitches = fun pipeName -> [ $"--fsi-server-client-pid:{earlier.ProcessId}"; $"--fsi-server-jsonrpc:{pipeName}" ]
+        )
+
+    session.Initialize() |> ignore
+
+    (earlier :> IDisposable).Dispose()
+
+    Assert.False(session.WaitForExit 5_000, "the session followed the owner named first")
+    Assert.True(succeeded (session.Execute "1 + 1"))
+
 //-------------------------------------------------------------------------
 // What ships
 //-------------------------------------------------------------------------

tests/FSharp.Compiler.Interactive.Server.Tests/FsiServerHarness.fs

@@ -111,7 +111,7 @@ type FsiServerHarness
             locateFsi (defaultArg fsiDirectory (fsiOutputDirectory ()))
 
         let serverSwitches =
-            defaultArg serverSwitches (fun pipeName -> [ $"--fsi-server-jsonrpc:{pipeName}" ])
+            defaultArg serverSwitches (fun pipeName -> [ $"{CommandLine.ServerOption}{pipeName}" ])
 
         let arguments =
             [
@@ -229,7 +229,7 @@ type FsiServerHarness
         let deadline = DateTime.UtcNow + defaultArg timeout (TimeSpan.FromSeconds 30.0)
 
         let rec wait () =
-            if this.StandardOutput.Contains text then true
+            if this.StandardOutput.Contains(text, StringComparison.Ordinal) then true
             elif DateTime.UtcNow > deadline then false
             else
                 Thread.Sleep 50
@@ -331,10 +331,10 @@ let diagnostics (result: ExecutionResult) =
     | items -> items
 
 let errors result =
-    diagnostics result |> Array.filter (fun d -> d.severity = "error")
+    diagnostics result |> Array.filter (fun d -> String.Equals(d.severity, "error", StringComparison.Ordinal))
 
 let warnings result =
-    diagnostics result |> Array.filter (fun d -> d.severity = "warning")
+    diagnostics result |> Array.filter (fun d -> String.Equals(d.severity, "warning", StringComparison.Ordinal))
 
 let succeeded (result: ExecutionResult) = result.success
 

tests/FSharp.Compiler.Interactive.Server.Tests/SubmissionAnalysisTests.fs

@@ -0,0 +1,96 @@
+// Copyright (c) Microsoft Corporation.  All Rights Reserved.  See License.txt in the project root for license information.
+
+/// Tests for the rule that decides whether Enter submits an interaction or adds another line.
+///
+/// The rule is what a user feels on every keystroke, and it is easy to get subtly wrong: a bracket
+/// inside a string, a terminator inside a comment, a line that merely looks finished. The analysis
+/// is lexical so that it can run on the UI thread, which makes these cases worth pinning down.
+module FSharp.Compiler.Interactive.Server.Tests.SubmissionAnalysisTests
+
+open Xunit
+
+open Microsoft.VisualStudio.FSharp.Editor
+open Microsoft.VisualStudio.FSharp.Interactive
+
+// The lexer the Visual Studio tooling runs on, which the window is handed rather than compiling against.
+let private scanners = FSharpLexicalScannerFactory() :> ILexicalScannerFactory
+
+let private assertComplete text =
+    Assert.True(SubmissionAnalysis.isComplete scanners text, $"expected a complete submission: <<{text}>>")
+
+let private assertIncomplete text =
+    Assert.False(SubmissionAnalysis.isComplete scanners text, $"expected an incomplete submission: <<{text}>>")
+
+[<Fact>]
+let ``an explicit terminator always submits`` () =
+    assertComplete "1 + 1;;"
+    assertComplete "let f x =\n    x + 1\n;;"
+    // Even mid-construct: the user asked for it.
+    assertComplete "let xs = [1; 2];;"
+
+[<Fact>]
+let ``a finished expression submits without a terminator`` () =
+    assertComplete "1 + 1"
+    assertComplete "printfn \"hi\""
+    assertComplete "let x = 40"
+    assertComplete "let f a b =\n    a + b"
+
+[<Fact>]
+let ``a line that visibly continues takes another line`` () =
+    assertIncomplete "let x ="
+    assertIncomplete "fun x ->"
+    assertIncomplete "1 +"
+    assertIncomplete "if true then"
+
+[<Fact>]
+let ``an unclosed bracket takes another line`` () =
+    assertIncomplete "printfn (\"a\""
+    assertIncomplete "let xs = [1; 2"
+    assertIncomplete "let xs = [| 1; 2"
+    assertIncomplete "let r = {| A = 1"
+
+[<Fact>]
+let ``closed brackets do not hold the submission open`` () =
+    assertComplete "printfn (\"a\")"
+    assertComplete "let xs = [1; 2]"
+    assertComplete "let xs = [| 1; 2 |]"
+
+[<Fact>]
+let ``an unterminated string or comment takes another line`` () =
+    assertIncomplete "let s = \"abc"
+    assertIncomplete "(* comment"
+
+[<Fact>]
+let ``brackets and terminators inside a string do not count`` () =
+    // The contents of a literal are not code, so neither the brackets nor the ';;' in these change
+    // whether the submission is finished.
+    assertComplete "let s = \"([{\""
+    assertComplete "let s = \"a;;b\""
+
+[<Fact>]
+let ``a string literal can end a submission`` () =
+    // The last token here is the literal, not the '=' before it.
+    assertComplete "let greeting = \"hello\""
+
+[<Fact>]
+let ``a terminator inside a string is not a terminator`` () =
+    assertIncomplete "let s = \";;"
+
+[<Fact>]
+let ``a comment does not change what the last token was`` () =
+    assertComplete "let x = 1 // ([\n"
+    assertComplete "(* c *) let x = 1"
+    assertIncomplete "let x = // nothing yet"
+
+[<Fact>]
+let ``an empty submission is allowed through`` () =
+    // The window uses an empty submission to start a session that has gone away.
+    assertComplete ""
+    assertComplete "   \n  "
+
+[<Fact>]
+let ``the terminator is added only when it is missing`` () =
+    Assert.Equal("1 + 1;;", SubmissionAnalysis.withTerminator scanners "1 + 1;;")
+    Assert.Equal("1 + 1\n;;", SubmissionAnalysis.withTerminator scanners "1 + 1")
+    // A ';;' that is only part of a string does not count as one.
+    Assert.Equal("let s = \"a;;b\"\n;;", SubmissionAnalysis.withTerminator scanners "let s = \"a;;b\"")

vsintegration/Vsix/Directory.Build.props

@@ -8,6 +8,8 @@
     <VSSDKTargetPlatformRegRootSuffix>$(VSRootSuffix)</VSSDKTargetPlatformRegRootSuffix>
     <!-- Path to the locally built F# compiler for use during VSIX debugging -->
     <FSharpCompilerPathForDebuggingLocally>$(ArtifactsDir)bin\fscAnyCpu\$(Configuration)\net472\</FSharpCompilerPathForDebuggingLocally>
+    <!-- Same for F# Interactive: the installed SDK's fsi does not know the JSON-RPC option yet -->
+    <FSharpInteractivePathForDebuggingLocally>$(ArtifactsDir)bin\fsi\$(Configuration)\net472\fsi.exe</FSharpInteractivePathForDebuggingLocally>
     <CreateVsixContainer>true</CreateVsixContainer>
     <PublishUrl>publish\</PublishUrl>
     <Install>true</Install>

vsintegration/Vsix/VisualFSharpFull/Properties/launchSettings.json

@@ -12,7 +12,8 @@
         "FSharpPreferAnyCpuTools": "true",
         "Fsc_NetFramework_ToolPath": "$(FSharpCompilerPathForDebuggingLocally)",
         "Fsc_NetFramework_AnyCpu_ToolExe": "fscAnyCpu.exe",
-        "FSHARP_OTEL_EXPORT": ""
+        "FSHARP_OTEL_EXPORT": "",
+        "FSHARP_INTERACTIVE_PATH": "$(FSharpInteractivePathForDebuggingLocally)"
       }
     },
     "OTEL Export": {
@@ -27,7 +28,8 @@
         "FSharpPreferAnyCpuTools": "true",
         "Fsc_NetFramework_ToolPath": "$(FSharpCompilerPathForDebuggingLocally)",
         "Fsc_NetFramework_AnyCpu_ToolExe": "fscAnyCpu.exe",
-        "FSHARP_OTEL_EXPORT": "http://127.0.0.1:4317"
+        "FSHARP_OTEL_EXPORT": "http://127.0.0.1:4317",
+        "FSHARP_INTERACTIVE_PATH": "$(FSharpInteractivePathForDebuggingLocally)"
       }
     }
   }

vsintegration/Vsix/VisualFSharpFull/Source.extension.vsixmanifest

@@ -34,6 +34,7 @@
       <Action Type="Ngen" Path="FSharp.ProjectSystem.FSharp.dll" />
       <Action Type="Ngen" Path="FSharp.ProjectSystem.PropertyPages.dll" />
       <Action Type="Ngen" Path="FSharp.VS.FSI.dll" />
+      <Action Type="Ngen" Path="FSharp.Interactive.Window.dll" />
     </Actions>
   </Installer>
   <Dependencies>
@@ -48,10 +49,12 @@
     <Asset Type="Microsoft.VisualStudio.VsPackage" d:Source="File" Path="FSharp.LanguageService.Base.pkgdef" />
     <Asset Type="Microsoft.VisualStudio.VsPackage" d:Source="File" Path="FSharp.LanguageService.pkgdef" />
     <Asset Type="Microsoft.VisualStudio.VsPackage" d:Source="File" Path="FSharp.Editor.pkgdef" />
+    <Asset Type="Microsoft.VisualStudio.VsPackage" d:Source="File" Path="FSharp.Interactive.Window.pkgdef" />
 
     <Asset Type="Microsoft.VisualStudio.MefComponent" d:Source="Project" d:ProjectName="FSharp.Editor" Path="|FSharp.Editor|" />
     <Asset Type="Microsoft.VisualStudio.Analyzer" d:Source="Project" d:ProjectName="FSharp.Editor" Path="|FSharp.Editor|" />
     <Asset Type="Microsoft.VisualStudio.MefComponent" d:Source="Project" d:ProjectName="ProjectSystem.Base" Path="|ProjectSystem.Base|" />
+    <Asset Type="Microsoft.VisualStudio.MefComponent" d:Source="Project" d:ProjectName="FSharp.Interactive.Window" Path="|FSharp.Interactive.Window|" />
 
     <Asset Type="Microsoft.VisualStudio.ItemTemplate" d:Source="Project" Path="ItemTemplates" d:TargetPath="|AppConfig;TemplateProjectOutputGroup|" d:ProjectName="AppConfig" d:VsixSubPath="ItemTemplates" />
     <Asset Type="Microsoft.VisualStudio.ItemTemplate" d:Source="Project" Path="ItemTemplates" d:TargetPath="|CodeFile;TemplateProjectOutputGroup|" d:ProjectName="CodeFile" d:VsixSubPath="ItemTemplates" />
@@ -63,6 +66,7 @@
   </Assets>
   <Prerequisites>
     <Prerequisite Id="Microsoft.VisualStudio.Component.CoreEditor" Version="[|%CurrentProject%;GetVSGeneralVersion|,)" DisplayName="Visual Studio core editor" />
+    <Prerequisite Id="Microsoft.VisualStudio.InteractiveWindow" Version="[4.0.0.0,5.0.0.0)" DisplayName="Interactive Window" />
   </Prerequisites>
 </PackageManifest>
 

vsintegration/Vsix/VisualFSharpFull/VisualFSharp.Core.targets

@@ -127,6 +127,15 @@
       <Private>True</Private>
     </ProjectReference>
 
+    <ProjectReference Include="$(FSharpSourcesRoot)\..\vsintegration\src\FSharp.Interactive.Window\FSharp.Interactive.Window.fsproj">
+      <Name>FSharp.Interactive.Window</Name>
+      <IncludeOutputGroupsInVSIX>BuiltProjectOutputGroup%3bGetCopyToOutputDirectoryItems%3bPkgDefProjectOutputGroup%3bSatelliteDllsProjectOutputGroup%3b</IncludeOutputGroupsInVSIX>
+      <IncludeOutputGroupsInVSIXLocalOnly>DebugSymbolsProjectOutputGroup%3b</IncludeOutputGroupsInVSIXLocalOnly>
+      <Ngen>true</Ngen>
+      <NgenPriority>2</NgenPriority>
+      <Private>True</Private>
+    </ProjectReference>
+
     <ProjectReference Include="$(FSharpSourcesRoot)\..\vsintegration\src\FSharp.UIResources\FSharp.UIResources.csproj">
       <Project>{c4586a06-1402-48bc-8e35-a1b8642f895b}</Project>
       <Name>FSharp.UIResources</Name>