GitWorld Phase 2 — Unreal walkable worlds

Objective

Move the completed browser-local GitWorld concept into a real-time Unreal project with a walkable third-person space, repository-owned sandbox state, visible build progress, and a high-resolution rendering profile.

Player experience

The player spawns in a GitWorld map containing repository districts. Each repository is an AGitWorldRepoWorld actor with its own deterministic snapshot, geometry, events, and terminal transcript. Walking into an AGitWorldRepoPortal activates that repository in the world subsystem. Build ticks change district geometry and the sign above the world, so construction is visible in-world rather than represented only by UI.

Architecture

GitWorldSimulation.* — deterministic, headless repository state transitions and terminal output.
AGitWorldRepoWorld — one sandboxed repository world; owns its snapshot, generated blocks, sign, and compute result.
AGitWorldRepoPortal — overlap trigger that switches the active repository when the player walks in.
UGitWorldWorldSubsystem — registry and active-world selection; no repository actor mutates another repository’s state.
FGitWorldCudaBridge — optional dynamic CUDA DLL boundary with a deterministic CPU fallback.
AGitWorldGameMode — temporary demo catalog for pax-coder, agent-minefield, and cuda-lab; replace with a data asset in Phase 3.

Rendering and 8K target

Config/DefaultEngine.ini enables a DX12-oriented Nanite/Lumen profile, virtual shadow maps, hardware ray tracing, and a 7680×4320 game-user resolution target. Use r.SetRes 7680x4320f for a desktop viewport or Movie Render Queue for a high-resolution capture. A real 8K interactive session is a performance target, not a promise that every GPU can sustain 60 FPS at native resolution.

The local machine currently exposes an RTX 3080 with 10,240 MiB VRAM. Unreal Editor and nvcc were not available on PATH during scaffold validation, so Unreal compilation, CUDA device execution, and native 8K frame-time measurement remain pending until those tools are installed.

Run when Unreal is installed

Right-click GitWorldUnreal.uproject and generate Visual Studio project files.
Build GitWorldUnrealEditor in Development Editor / Win64.
Open the project, press Play, and walk with the default pawn.
Confirm the repository sign, build tick, portal activation, and terminal transcript.
If desired, build Compute/GitWorldCuda.dll and place it in Binaries/Win64/ to enable the CUDA compute pass.

Local verification

From the parent gitworld folder:

node tools/verify-phase2.mjs

This verifies the project manifest, Unreal source contract, isolated repository identifiers, CUDA boundary, and 8K settings without requiring Unreal or CUDA to be installed.