Document MVP shelter wall piece

AGRARIAN_DEVELOPMENT_ROADMAP.md

@@ -615,7 +615,10 @@ Target deliverable: A small group can join a server, spawn into one biome, gathe
   footprint at the snapped placement location for MVP development builds.
 - [x] Add placement validation.
 - [x] Add basic shelter piece.
-- [ ] Add wall piece if needed.
+- [x] Add wall piece if needed. For the kit-based MVP style, the wall piece is
+  the craftable `primitive_wall_panel` inventory construction part consumed by
+  the primitive shelter recipe; separately placeable modular walls remain
+  deferred to `0.2.E Permanent Structures`.
 - [ ] Add roof piece if needed.
 - [ ] Add door/opening if needed.
 - [x] Add resource cost validation.

Docs/TechnicalDesignDocument.md

@@ -86,6 +86,9 @@ Early runtime systems should remain small and explicit:
   as inventory parts and then combined into a single placeable primitive
   shelter actor. Fully modular wall-by-wall construction is deferred to
   permanent structures so the first survival loop remains reliable.
+- The MVP wall piece is `primitive_wall_panel`, a craftable inventory
+  construction part consumed by the primitive shelter recipe rather than an
+  independently placed wall actor.
 - `UAgrarianBuildingPlacementComponent` owns the MVP placement preview. It
   traces from the player view, snaps to the configured grid, validates distance
   and collision, broadcasts Blueprint-readable preview state, and draws a

Scripts/verify_shelter_wall_piece.py

@@ -0,0 +1,34 @@
+#!/usr/bin/env python3
+from pathlib import Path
+
+ROOT = Path(__file__).resolve().parents[1]
+ROADMAP = ROOT / "AGRARIAN_DEVELOPMENT_ROADMAP.md"
+TECHNICAL_DESIGN = ROOT / "Docs" / "TechnicalDesignDocument.md"
+ITEMS = ROOT / "Scripts" / "setup_item_definitions.py"
+RECIPES = ROOT / "Scripts" / "setup_recipe_definitions.py"
+RECIPE_VERIFY = ROOT / "Scripts" / "verify_recipe_definitions.py"
+
+
+def compact(path: Path) -> str:
+    return " ".join(path.read_text(encoding="utf-8").split())
+
+
+def require(path: Path, text: str) -> None:
+    data = compact(path)
+    if text not in data:
+        raise SystemExit(f"FAIL: {path.relative_to(ROOT)} missing required text: {text}")
+
+
+def main() -> None:
+    require(ROADMAP, "[x] Add wall piece if needed.")
+    require(ROADMAP, "primitive_wall_panel")
+    require(TECHNICAL_DESIGN, "The MVP wall piece is `primitive_wall_panel`")
+    require(ITEMS, '"item_id": "primitive_wall_panel"')
+    require(RECIPES, '"recipe_id": "primitive_wall_panel"')
+    require(RECIPES, '("primitive_wall_panel", 4)')
+    require(RECIPE_VERIFY, '"recipe_id": "primitive_wall_panel"')
+    print("PASS: MVP shelter wall piece is defined as a craftable construction part.")
+
+
+if __name__ == "__main__":
+    main()