feat(explore): a commandlet -- 91x faster, and the first real PICTURE

Every experiment in this project cost a build + full-suite cycle. The
landing task took 52 of them over ~9 hours. And nobody could SEE the world:
every visual judgement all session was made on density SLICES -- diagrams,
not pictures. That is how a floor heaving 1.4 m every two metres got
described as "roughness visible but modest" while Jahni spotted it in
thirty seconds by walking it.

-run=VoxelForgeExplore, editor-only module, three modes, one build many runs:

  render  raymarched PNGs, fixed 0.25-voxel step + 10 bisection iterations
          (NOT sphere tracing -- the op stack yields density, not a signed
          distance, so a long step tunnels through walls). Three views, each
          with a 1.76 m human marker in frame, because every scale mistake
          here came from numbers with no body beside them.
  walk    an agent using the EXISTING VF player-fit stencil, never its own
          movement model -- two definitions of "can a player stand here"
          would drift and we could not tell which was lying.
  export  OBJ through the canonical UVoxelMarchingCubesMesher. No second
          mesher; a forked meshing invariant is the bug this project keeps
          paying for. 23.2 MB, 106,762 verts, 200,842 tris for 128^3.

⭐ THE NUMBER THAT JUSTIFIES IT: the full automation run takes 4,396 s
(73m16s). The commandlet does all three modes in 48.1 s wall, 5.9 s of
which is engine startup. ~91x faster. And I had guessed the suite cost
~90 s -- it is 73 MINUTES. The iteration loop was far more expensive than
I knew.

First real walk metrics on the Maze (seed 0, slot 4):
  distance 214 m · tortuosity 4.98 · dead ends 0.935/100 m
  narrow-gap events 0 · reachable fit fraction 3.01%
  result NotConnectedAtThisResolution
Tortuosity ~5 is a genuinely winding route, which is right for a maze.
3% reachable is not.

Editor Development build clean. SHIPPING build clean with the receipt
containing VoxelForge and NOT VoxelForgeEditor -- the instrument cannot
reach a packaged game. Automation 32/32, 0 failed.

⚠️ Codex initially shipped this UNBUILT, and correctly: I omitted the
## Validation section from that spec, so it fell back to CLAUDE.md's
"NEVER build or compile". 100+ compile errors from three causes -- bare
TCondensedJsonPrintPolicy and TJsonWriter needing their template
arguments, and a missing UObject/Package.h. That include is the SECOND
miss this session, so CODEMAP §6 now carries the gotcha.

⚠️ Unrelated, found in passing: VoxelForge.uplugin does not declare
RealtimeMeshComponent although the runtime module uses it.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01K8V9my1PL68pmQb2gutZZV

CODEMAP.md

@@ -112,9 +112,10 @@ remains `0`, and lateral regions remain gated off.
 ### 3.1 Module & build
 | File | Role |
 |------|------|
-| `../../VoxelForge.uplugin` | Plugin manifest. One Runtime module `VoxelForge`. Beta. |
+| `../../VoxelForge.uplugin` | Plugin manifest. Runtime module `VoxelForge` plus the Editor-only `VoxelForgeEditor` commandlet module. Beta. |
 | `VoxelForge.Build.cs` | Deps: Core, CoreUObject, Engine, **GameplayTags**, **RealtimeMeshComponent**. |
 | `Public/VoxelForgeModule.h` / `Private/VoxelForgeModule.cpp` | `FVoxelForgeModule` boilerplate (Startup/Shutdown just log). |
+| `Source/VoxelForgeEditor/VoxelForgeEditor.Build.cs` / `Private/VoxelForgeExploreCommandlet.*` | Editor/commandlet-only `-run=VoxelForgeExplore`; owns bounded render/`VF_` walk/OBJ export orchestration and is not linked by Game/Shipping. |
 | `Public/VoxelStats.h` / `Private/VoxelStats.cpp` | `stat VoxelForge` DWORD counters for tile classification, skipping, meshing, operator-stack verdicts, and cave-bail diagnosis. The former ambiguous `Cave Bail Not Op Stack` is split into `Sole Slot`, `Boundary Tile`, `No Layout`, and late `Recheck` counters, so each increment names one guard/context. |
 
 ### 3.2 Foundational types — `Public/VoxelTypes.h` (no UClass, everyone includes it)
@@ -400,6 +401,16 @@ No UObject state, cache, actor, world, or PIE is required.
 | `VF_MeasureStrate` | One-grid/one-flood-fill strate metrics; resolves either the legacy centered square or the two-point fitted AABB, and refuses invalid bounds or a grid over `MaxCells`. |
 | `VF_AreConnected` | Coarse 6-connected BFS plus deterministic blocked-edge retries, with a full-resolution air recheck for every candidate route and explicit endpoint-solid, out-of-window, `NotConnectedAtThisResolution`, `CoarseLiedBudgetExhausted` (unknown), and connected outcomes; diagnostics include endpoint component facts and the retry count from that same grid. |
 | `VF_DiagnoseConnectivity` | The same query plus each mouth's air-component size/share and exact geometric distance to the nearest cell of the other component; proximity is measured in coarse-cell coordinates and does not claim a route through solid. |
+| `FVoxelPlayerFitWalkReport` / `VF_MeasurePlayerFitWalkWithSampler` | Editor-only experiential instrument over the existing exact `VF_` capsule/floor-fit mask: deterministic graph-walk distance, dead ends, reachable fit volume, and a labelled narrow-gap proxy; no second movement model. |
+
+`VoxelForgeExploreCommandlet` builds a transient, fixed-definition world and calls the production
+`UVoxelGenerator::GetDensityAt` and `UVoxelMarchingCubesMesher::GenerateMesh` paths. `render` uses
+fixed density samples (default 0.25 voxel) with bisection at sign crossings instead of sphere tracing;
+`walk` uses `VF_MeasurePlayerFitWalkWithSampler`; `export` calls the canonical 32³ mesher in a
+deterministic tile grid (four tiles per axis for the 128³ default), streams only its returned tile
+arrays into metre-space OBJ plus `manifest.json` (canonical UVs remain voxel-space), and never retains the full region mesh. Output JSON/manifest are emitted by fixed-order writers and compared with a second
+serialization before it is written. The commandlet keeps `WorldRadiusVoxels=0`, does not touch an
+authored asset or diff layer, and refuses bounded-grid/export requests before allocating them.
 
 ### 3.7 Cave morphology (SDF rooms/tunnels) — `Public/VoxelCaveMorphology.h` + `.cpp`
 Header is rich with inline docs. Two namespaces + a per-chunk cache system.
@@ -794,6 +805,8 @@ Stage order (negative=solid throughout). Each stage's anchor:
   are dropped in `ProcessPendingChunks`. Always carry the epoch through new async paths.
 - **Generated code** under `Intermediate/` and `Binaries/` is build output — never edit.
   `*.generated.h` / `*.gen.cpp` are UHT output for the `UCLASS`/`USTRUCT` above.
+- **`UPackage` completeness:** files that call `NewObject(..., GetTransientPackage(), ...)` must include
+  `UObject/Package.h` directly; files that do not include `VoxelForgeTestFixture.h` do not get it transitively.
 
 ---