@@ -118,13 +118,35 @@
                this.controllerPos = ctrlPos;
            }
            // Propagate group to all members
            // Propagate group to all members and resize the controller if needed
            int newCols = group.totalCols(COLS_PER_BLOCK);
            int newRows = group.totalRows(ROWS_PER_BLOCK);
            for (BlockPos memberPos : group.getMembers()) {
                if (memberPos.equals(getBlockPos())) continue;
                BlockEntity be = level.getBlockEntity(memberPos);
                if (be instanceof TerminalBlockEntity memberBE) {
                    memberBE.screenGroup = group;
                    boolean isCtrl = ctrlPos.equals(memberPos);
                    memberBE.controllerPos = isCtrl ? null : ctrlPos;
                    memberBE.controllerPos = ctrlPos.equals(memberPos) ? null : ctrlPos;
                    // If this member is the controller and has a running terminal,
                    // resize it to match the new group dimensions
                    if (isCtrl && memberBE.terminalStarted && memberBE.terminal != null) {
                        if (memberBE.cols != newCols || memberBE.rows != newRows) {
                            memberBE.cols = newCols;
                            memberBE.rows = newRows;
                            memberBE.terminal.resize(newCols, newRows);
                            int[] dims = memberBE.terminal.getDimensions();
                            if (dims != null && dims.length >= 2) {
                                memberBE.pixelWidth = dims[0];
                                memberBE.pixelHeight = dims[1];
                                memberBE.pixelBuffer = ByteBuffer.allocateDirect(dims[0] * dims[1] * 4);
                            }
                        }
                    } else if (isCtrl) {
                        memberBE.cols = newCols;
                        memberBE.rows = newRows;
                    }
                }
            }
        } else {

@@ -487,6 +487,41 @@
    // ==================== MULTI-BLOCK WIRING (block entity integration) ====================
    /** Placing extension next to an already-running controller resizes it. */
    @GameTest(template = EMPTY_STRUCTURE, timeoutTicks = 40)
    public void extensionResizesRunningController(GameTestHelper h) {
        BlockPos a = new BlockPos(1, 1, 1);
        BlockPos b = new BlockPos(2, 1, 1);
        // Place block A first (simulating player placing and starting terminal)
        h.setBlock(a, terminalState(Direction.NORTH));
        h.runAfterDelay(3, () -> {
            TerminalBlockEntity beA = assertTerminalEntity(h, a);
            // Verify A starts with default single-block dimensions
            if (beA.getCols() != 80) throw new AssertionError("A should start at 80 cols");
            if (beA.getRows() != 24) throw new AssertionError("A should start at 24 rows");
            // Now place block B next to it
            h.setBlock(b, terminalState(Direction.NORTH));
            h.runAfterDelay(5, () -> {
                // Trigger rescan from the NEW block (what onPlace does)
                TerminalBlockEntity beB = assertTerminalEntity(h, b);
                beB.rescanGroup();
                // The controller's dimensions should have been updated
                TerminalBlockEntity ctrl = beA.isExtension() ? beB : beA;
                // 2 blocks wide × 40 cols/block = 80 cols, 1 block tall × 12 rows/block = 12 rows
                if (ctrl.getCols() != 80) {
                    throw new AssertionError("Controller should have 80 cols after group, got " + ctrl.getCols());
                }
                if (ctrl.getRows() != 12) {
                    throw new AssertionError("Controller should have 12 rows after group, got " + ctrl.getRows());
                }
                h.succeed();
            });
        });
    }
    /** rescanGroup() assigns controller and extension roles in a 2x1. */
    @GameTest(template = EMPTY_STRUCTURE, timeoutTicks = 40)
    public void rescanAssignsControllerAndExtension(GameTestHelper h) {