#compile-error

On engine 26.07 both [GameResource] and NavMesh.GetSimplePath are marked [Obsolete] (CS0618), so a zero-warnings build gate fails on them. Replace [GameResource(...)] with [AssetType(...)] and GetSimplePath with NavMesh.CalculatePath, which returns a NavMeshPath of NavMeshPathPoint (not List<Vector3>).

@ref on a private field compiles with only a CS0649 warning: the ref stays null at runtime. Bind to a property instead.

public int X { get; init; } = SomeClass.SomeProperty; passes headless dotnet build but fails the editor compile with CS0182: the editor's code generator embeds initializers where only constants are legal. Default to a constant sentinel and resolve later.

A single-line XML doc comment that shares a line with the field it documents pulls the declaration into the comment. The compiler then sees no field at all. Nothing fails at the comment site. The break shows up later as a 'does not contain a definition' error wherever the field is used, which reads like a typo or a missing using. Put every XML doc comment on its own line, directly above the member.

A custom GameResource with a file extension longer than 8 characters silently never registers as a compilable source type. Every asset fails with "no source file." Keep extensions to 8 lowercase chars or fewer.

ModelRenderer.CastShadows doesn't exist as a settable property: use renderer.SceneObject.Flags.CastShadows instead.

compile_status is fully green and the editor accepts edits, but Play executes the OLD code: touch, syntax-error cycling, and play restart all fail. Only a full editor process restart clears it.

An unqualified FileSystem compiles in a game assembly but CS0104s in an editor assembly: fully-qualify Sandbox.FileSystem in editor code.

ERROR models or white materials persist after fixing the source: delete the compiled artifact AND touch the source file to force recompilation, or poke asset_compile per source file.

A git worktree at a different directory depth than the main checkout breaks the generated csproj's relative references to the sbox install: dotnet build fails with missing-assembly errors.

compile_status shows Success and dotnet build is green, but play mode reports errors for symbols and lines that no longer exist in source: the play-mode hotloader compiled a stale mid-edit snapshot.

The editor discovers a library under Libraries/ only if the folder contains exactly one .sbproj file. A hand-vendored library without one is silently ignored, producing a wall of CS0246 errors on every type it defines.

A consumer game plus a vendored library can be compile-gated fully offline using two scratch csprojs against the editor install's prebuilt base library DLL.

OnAfterTreeRender(bool) is a Panel hook: on a PanelComponent it fails with CS0115; use parameterless OnTreeBuilt() or OnTreeFirstBuilt().

Nesting @{ } inside an already-open Razor code block (like @if or @for) causes RZ1010: you're already in C#, so drop the @.

A freshly-scaffolded project's Assembly.cs can be missing global using System. Transplanted code using Math/MathF fails with CS0103.

ScenePanel's Camera property is GET-ONLY. Assigning a new SceneCamera fails with CS0200. Configure the existing camera in place and build the preview world manually.

Use TextEntry with onsubmit and OnTextEdited: standard Blazor input bindings compile but are not how the engine UI works.

An untyped or expression-bodied lambda on TextEntry.OnTextEdited fails with CS8917 or CS0029. Use an explicit param type plus a block body.

Shader field support is unknown and no .shader source exists: check the install's templates/ folder for authoritative syntax instead of grepping sibling projects.