glue-project-types

name	glue-project-types
description	How Glue decides what kind of project it opened, and the seams that stop it writing code/csproj for FRB2 projects. Triggers: ProjectCreator, Frb2Project, IsMaintainedByGlue, CodeWritePolicy, GenerateCode, Frb2CodeGenerator, "could not determine project type", LocateSolution.

Glue Project Types

Where the decision happens

File	Purpose
Glue/VSHelpers/Projects/ProjectCreator.cs	The only place a .csproj becomes a ProjectBase. FRB2 check first, then the DefineConstants cascade.
Glue/VSHelpers/Projects/Frb2ProjectDetector.cs	Rule list identifying an FRB2 game project from its project items.
GlueCommon/VSHelper/Projects/ProjectBase.cs	ContentDirectory and IsMaintainedByGlue, the two properties everything downstream keys off.
Glue/Plugins/ExportedImplementations/CodeWritePolicy.cs	The one rule deciding whether Glue may write C# into the loaded project.

Project type comes from DefineConstants, not from references

ProjectCreator.TryGetProjectTypeFromDefineConstants picks the ProjectBase subclass by matching DESKTOP_GL / ANDROID / IOS / FNA / BLAZORGL against the csproj's DefineConstants, plus a minimum TargetFrameworkVersion.

Landmine: a project that defines none of those does not degrade gracefully — Glue shows "Could not determine project type", offers a manual-pick dialog, and returns null, and ProjectLoader then skips loading entirely. A perfectly valid modern SDK-style csproj can hit this simply by not carrying an FRB-specific DefineConstants. Anything identifying a project by its references has to run before that cascade, in CreatePlatformSpecificProject.

FRB2 projects: reads yes, writes no

An FRB2 game reads Glue's .gluj/.glsj/.glej JSON at runtime and owns all of its own C#, so Frb2Project sets IsMaintainedByGlue = false. The csproj is still fully loaded and read — it is what resolves the project directory and Content folder every relative path in the JSON hangs off. Only writes are suppressed, at four seams:

Seam	Suppresses
VisualStudioProject.Save + the duplicate-resolution save in Load	Every write of the .csproj to disk
GlueCommands.GenerateCodeCommands (resolves to NoCodeGenerationCommands)	Everything reached through IGenerateCodeCommands
FileCommands.SaveIfDiffers	Any .cs written as text, whoever wrote it
ProjectCommands.CreateAndAddCodeFile / CreateAndAddPartialFile	The empty placeholder created before anything fills it

Landmine: the last two are not redundant with NoCodeGenerationCommands. A real chunk of Glue's code generation never goes through IGenerateCodeCommands at all — CodeBuildItemAdder drops embedded resource files (Performance/IEntityFactory, Performance/PoolList), CameraSetupCodeGenerator writes Setup/CameraSetup.Generated.cs, and ContentPipelinePlugin's AliasCodeGenerator writes FileAliases.Generated.cs — all on glux load, before and outside any GenerateAllCode call. Suppressing only the interface leaves those writing into the project.

Plugin generators that call FileManager.SaveText directly (Platformer/TopDown/Racing CSV and enum generators, Gum, GameCommunication) still bypass all of this. They only fire for projects that opt into those behaviors.

Frb2Project.ContentDirectory and GlueProjectSubdirectory are both "Content/FrbEditor/" — unlike FRB1, the .gluj does not sit beside the .csproj. Everything Glue authors for an FRB2 project lives under that one folder so deleting it removes every trace of the editor, and every relative path in the JSON resolves against it.

FRB2 code generation is opt-in, and not via IsMaintainedByGlue

GlueProjectSave.GenerateCode (default false) turns on typed accessors for an FRB2 project's Screens/Entities, written by Glue/CodeGeneration/Frb2CodeGenerator.cs via Frb2GenerateCodeCommands.

Landmine: the opt-in is CodeWritePolicy.GeneratesFrb2Code, deliberately not ProjectBase.IsMaintainedByGlue, which stays permanently false for Frb2Project. That flag gates all four seams in the table above at once, so routing the setting through it hands an FRB2 project the entire FRB1 pipeline: Glue rewrites the .csproj, and every generator in the landmine above writes its FRB1-only output into a project that cannot compile it. GenerateCodeCommands therefore checks GeneratesFrb2Code before the IsMaintainedByGlue early-out.

Landmine: Frb2CodeGenerator writes both halves of the partial class itself rather than through FileCommands.SaveIfDiffers / CodeProjectHelper.CreateAndAddPartialGeneratedCodeFile. Those add a nested .csproj item and honour the FRB1 write-gate, neither of which applies — FRB2's SDK-style project already globs **/*.cs. Both halves resolve through IFileCommands.GetGeneratedCodeFilePath / GetCustomCodeFilePath, which are rooted at CurrentGlueProjectDirectory (the .gluj's folder). Composing either from FileManager.RelativeDirectory instead is identical for FRB1 and splits the pair across directories for FRB2.

The tree view's Code/Events nodes still key off WritesCodeForCurrentProject, so an opted-in project's generated files show up on disk but not in Glue's Explorer tree.

Solution lookup can fail a load

ProjectSyncer.LocateSolution throws when it finds no solution file, and that exception surfaces through GlueState.CurrentSlnFileName during ProjectLoader.LoadProject — so an unrecognized solution format is a project that will not open, not a cosmetic gap. It searches the project directory, one up, and two up, for both .sln and .slnx, then verifies the file's text actually names the .csproj.

Testing

Frb2ProjectDetector.IsFrb2Project takes a plain item-type/include list, so detection tests need no MSBuild evaluation. For anything needing a real ProjectBase, see glue-unit-test-bootstrap — TestVisualStudioProjectFactory (bare non-SDK csproj, no SDK resolution) and GoldProject.LoadInGlueAsync (the real loader) are the two rungs.

Landmine: a test asserting "loading this project generated nothing" depends on which plugins are registered, and that is process-wide state another test may have set. Call GlueTestBootstrap.EnsureGameProjectPluginsRegistered() so the assertion means the same thing in isolation and mid-suite.