C++ Developer API

Use the native Developer API from an Editor-only C++ plugin or tool. Add the Locus module to the consuming editor module’s dependencies, include Locus.h for acquisition, and include Developer/LocusDeveloperApi.h for requests and results.

Lifetime and async contract

GetLocusDeveloperApi() returns the active FLocusDeveloperApi, or nullptr outside the initialized Locus Editor lifetime.

• Acquire and submit on the Game Thread.
• Do not retain the API pointer across subsystem or module shutdown.
• Every completion runs exactly once on the Game Thread.
• Accepted work completes on a later tick of Locus’s existing executor.
• Admission failure can complete inline before submission returns.
• Prepare callback-owned state before submitting.
• Cancellation is cooperative. It can prevent queued work, but cannot interrupt repository work or retroactively cancel a committed mutation.
• Do not add blocking waits, sleeps, Game Thread pumping, or Future.Get().

The returned FLocusDeveloperRequestHandle exposes request identity and thread-safe cooperative Cancel().

Create a Document

#include "Locus.h"
#include "Developer/LocusDeveloperApi.h"

void CreateCombatDocument()
{
  FLocusDeveloperApi* Locus = GetLocusDeveloperApi();
  if (Locus == nullptr)
  {
    return;
  }

  FLocusDeveloperCreateDocumentRequest Request;
  Request.Path = TEXT("Design/Combat.md");
  Request.Markdown = TEXT("# Combat\n");
  Request.PresentationRoot =
    ELocusDeveloperDocumentPresentationRoot::LocusDocuments;

  FLocusDeveloperRequestHandle Handle = Locus->CreateDocument(
    MoveTemp(Request),
    [](TLocusDeveloperResult<FLocusDeveloperDocumentSnapshot> Result)
    {
      if (!Result.IsSuccess())
      {
        UE_LOG(LogTemp, Error, TEXT("Locus: %s"), *Result.Error.Message);
        return;
      }

      const FLocusDeveloperDocumentSnapshot& Document = Result.Value.GetValue();
      UE_LOG(LogTemp, Display, TEXT("Created %s"),
        *Document.Identity.RelativePath);
    });

  // Retain Handle only if this tool needs to offer cancellation.
}

The input path is relative to the selected concrete presentation root. The returned identity remains the authoritative ProjectDocuments-relative path.

Get, then update

Do not hide revision handling. Use the revision from the read result as the mutation precondition:

FLocusDeveloperGetDocumentRequest GetRequest;
GetRequest.Identity.RelativePath = TEXT("Design/Combat.md");

Locus->GetDocument(
  MoveTemp(GetRequest),
  [Locus](TLocusDeveloperResult<FLocusDeveloperDocumentSnapshot> GetResult)
  {
    if (!GetResult.IsSuccess())
    {
      return;
    }

    const FLocusDeveloperDocumentSnapshot& Current = GetResult.Value.GetValue();
    FLocusDeveloperUpdateDocumentRequest UpdateRequest;
    UpdateRequest.Identity = Current.Identity;
    UpdateRequest.ExpectedRevision = Current.Revision;
    UpdateRequest.Markdown = Current.Markdown + TEXT("\n## Abilities\n");

    Locus->UpdateDocument(
      MoveTemp(UpdateRequest),
      [](TLocusDeveloperResult<FLocusDeveloperDocumentSnapshot> Result)
      {
        if (Result.Error.Code ==
          ELocusDeveloperErrorCode::StaleRevision)
        {
          // Reread before reconsidering the mutation.
        }
      });
  });

Explicit Note scope

FLocusDeveloperCreateNoteRequest Request;
Request.Scope = ELocusDeveloperScope::Private;
Request.Title = TEXT("Local investigation");
Request.Body = TEXT("Not shared with the project repository.");
Request.Tags = {TEXT("investigation")};

FLocusDeveloperRequestHandle Handle = Locus->CreateNote(
  MoveTemp(Request),
  [](TLocusDeveloperResult<FLocusDeveloperNoteSnapshot> Result)
  {
    if (Result.IsSuccess())
    {
      const FLocusDeveloperNoteIdentifier Identity =
        Result.Value->Identity; // GUID + Private scope
    }
  });

Scope filters are equally explicit. All includes Private content; request Shared when a tool must not include it.

Basic Pin creation

FLocusDeveloperCreatePinRequest Request;
Request.Scope = ELocusDeveloperScope::Shared;
Request.WorldAssetPath = TEXT("/Game/Maps/Main.Main");
Request.WorldLabel = TEXT("Main");
Request.Location = FVector(120.0, 40.0, 180.0);
Request.Title = TEXT("Check encounter cover");
Request.PinType = ELocusDeveloperPinType::Issue;

FLocusDeveloperRequestHandle Handle = Locus->CreatePin(
  MoveTemp(Request),
  [](TLocusDeveloperResult<FLocusDeveloperPinSnapshot> Result)
  {
    if (!Result.IsSuccess())
    {
      UE_LOG(LogTemp, Warning, TEXT("Pin create failed: %s"),
        LexToString(Result.Error.Code));
    }
  });

Pin creation requires a supported saved project-owned world. Metadata updates preserve position, world, anchor, view, and scope.

See the Developer API overview for the operation matrix, identity contract, error taxonomy, revisions, and operation status.