Never rotate tunnels in place

src/lib/sim/BuildingSystem.cpp

@@ -1492,6 +1492,13 @@ bool BuildingSystem::isTileOccupied(QPoint tile) const
 std::optional<BuildingId> BuildingSystem::findRotateInPlaceTarget(
     BuildingType type, QPoint anchor, Rotation rot) const
 {
+    // Tunnel Entries and Tunnel Exits cannot be rotated in place; re-orienting a
+    // tunnel requires demolishing and re-placing it (REQ-BLD-ROTATE-IN-PLACE).
+    if (type == BuildingType::TunnelEntry || type == BuildingType::TunnelExit)
+    {
+        return std::nullopt;
+    }
+
     const BuildingDef* def = findBuildingDef(type);
     if (!def) { return std::nullopt; }
 

src/test/BuildingTest.cpp

@@ -1115,6 +1115,32 @@ TEST_CASE("BuildingSystem: findRotateInPlaceTarget returns nullopt when building
         bs.findRotateInPlaceTarget(BuildingType::Splitter, QPoint(0, 0), Rotation::East).has_value());
 }
 
+TEST_CASE("BuildingSystem: findRotateInPlaceTarget never rotates a tunnel in place",
+          "[building][rotate-in-place]")
+{
+    const GameConfig cfg = loadConfig();
+    BeltSystem belts(cfg.world.beltSpeed_tps);
+    int stock = 0;
+    std::mt19937 rng(0);
+    BuildingId nextBuildingId = 1;
+    BuildingSystem bs(cfg, belts,
+                      [&nextBuildingId]() { return nextBuildingId++; },
+                      [&stock](int n) { stock += n; },
+                      [](const std::string&, QVector2D, const std::optional<ShipLayoutConfig>&) {},
+                      [](const std::string&) -> bool { return true; },
+                      rng);
+
+    // Even with a coincident same-type tunnel under the ghost, rotate-in-place is
+    // never offered for tunnels (REQ-BLD-ROTATE-IN-PLACE exception).
+    bs.place(BuildingType::TunnelEntry, QPoint(-1, 0), Rotation::East, 0);
+    bs.place(BuildingType::TunnelExit,  QPoint(-2, 0), Rotation::East, 0);
+
+    REQUIRE_FALSE(
+        bs.findRotateInPlaceTarget(BuildingType::TunnelEntry, QPoint(-1, 0), Rotation::North).has_value());
+    REQUIRE_FALSE(
+        bs.findRotateInPlaceTarget(BuildingType::TunnelExit, QPoint(-2, 0), Rotation::North).has_value());
+}
+
 TEST_CASE("BuildingSystem: findRotateInPlaceTarget returns nullopt when footprints only partially overlap",
           "[building][rotate-in-place]")
 {