diff --git a/src/interact/mod.rs b/src/interact/mod.rs
index eb2d9db..817af3e 100644
--- a/src/interact/mod.rs
+++ b/src/interact/mod.rs
@@ -5,6 +5,9 @@
  */
 
 use crate::app::DungeonApp;
+pub use crate::exporter::types::{
+    door_edges_for, door_render_width, norm_edge as normalized_edge, window_render_width,
+};
 use crate::layout;
 use crate::ui::AddTool;
 use eframe::egui;
@@ -602,71 +605,6 @@ pub fn resize_hit_cells(
     cells
 }
 
-// Computes edges for.
-pub fn door_edges_for(
-    door: &layout::Door,
-    cols: usize,
-    rows: usize,
-) -> Vec<((usize, usize), (usize, usize))> {
-    let mut edges = Vec::new();
-    if door.from.0.abs_diff(door.to.0) + door.from.1.abs_diff(door.to.1) != 1 {
-        return edges;
-    }
-
-    let width = door_render_width(door).max(1) as isize;
-    let min_offset = -((width - 1) / 2);
-    let max_offset = width / 2;
-
-    if door.from.0 != door.to.0 {
-        let y = door.from.1 as isize;
-        for dy in min_offset..=max_offset {
-            let ny = y + dy;
-            if ny < 0 || ny >= rows as isize {
-                continue;
-            }
-            let a = (door.from.0, ny as usize);
-            let b = (door.to.0, ny as usize);
-            edges.push(normalized_edge(a, b));
-        }
-    } else {
-        let x = door.from.0 as isize;
-        for dx in min_offset..=max_offset {
-            let nx = x + dx;
-            if nx < 0 || nx >= cols as isize {
-                continue;
-            }
-            let a = (nx as usize, door.from.1);
-            let b = (nx as usize, door.to.1);
-            edges.push(normalized_edge(a, b));
-        }
-    }
-
-    edges
-}
-
-// Computes render width.
-pub fn door_render_width(door: &layout::Door) -> usize {
-    if door.span_width {
-        door.width.max(1)
-    } else {
-        1
-    }
-}
-
-// Computes render width.
-pub fn window_render_width(window: &layout::Window) -> usize {
-    if window.span_width {
-        window.width.max(1)
-    } else {
-        1
-    }
-}
-
-// Normalizes a cell edge so either endpoint order compares equal.
-pub fn normalized_edge(a: (usize, usize), b: (usize, usize)) -> ((usize, usize), (usize, usize)) {
-    if a <= b { (a, b) } else { (b, a) }
-}
-
 // Returns the screen center point for a grid cell.
 pub fn cell_center(geometry: &GridGeometry, col: usize, row: usize) -> egui::Pos2 {
     egui::pos2(
diff --git a/src/layout/generation/markers.rs b/src/layout/generation/markers.rs
index 3f050a0..fffce91 100644
--- a/src/layout/generation/markers.rs
+++ b/src/layout/generation/markers.rs
@@ -5,7 +5,7 @@
  */
 
 use super::super::types::{AreaMarker, Corridor, DungeonLayout, Room, Staircase};
-use super::super::utils::room_index_at_cell;
+use super::super::utils::{SimpleRng, room_index_at_cell, shuffle_items};
 use crate::seed;
 use crate::ui::UiSettings;
 use std::collections::HashSet;
@@ -600,29 +600,6 @@ pub fn random_stair_size(settings: &UiSettings, seed_value: u64) -> (usize, usiz
 }
 
 pub fn shuffle_with_seed<T>(items: &mut [T], seed: u64) {
-    let mut rng = StairShuffleRng::new(seed);
-    for idx in (1..items.len()).rev() {
-        let swap_idx = rng.next_u32() as usize % (idx + 1);
-        items.swap(idx, swap_idx);
-    }
-}
-
-pub struct StairShuffleRng {
-    pub state: u64,
-}
-
-impl StairShuffleRng {
-    // Creates a new instance with the given inputs.
-    pub fn new(seed: u64) -> Self {
-        Self { state: seed }
-    }
-
-    // Generates the next pseudo-random 32-bit value.
-    pub fn next_u32(&mut self) -> u32 {
-        self.state = self
-            .state
-            .wrapping_mul(6364136223846793005)
-            .wrapping_add(1442695040888963407);
-        (self.state >> 32) as u32
-    }
+    let mut rng = SimpleRng::new(seed);
+    shuffle_items(items, &mut rng);
 }
diff --git a/src/layout/utils.rs b/src/layout/utils.rs
index 92b810f..7e0693e 100644
--- a/src/layout/utils.rs
+++ b/src/layout/utils.rs
@@ -468,13 +468,18 @@ pub fn noisy_path(
     path
 }
 
-// Shuffle indices in place using the provided RNG.
-pub fn shuffle_indices(indices: &mut [usize], rng: &mut SimpleRng) {
-    if indices.len() <= 1 {
+// Shuffle any mutable slice in place using the provided RNG.
+pub fn shuffle_items<T>(items: &mut [T], rng: &mut SimpleRng) {
+    if items.len() <= 1 {
         return;
     }
-    for i in (1..indices.len()).rev() {
+    for i in (1..items.len()).rev() {
         let j = rng.range_inclusive(0, i);
-        indices.swap(i, j);
+        items.swap(i, j);
     }
 }
+
+// Shuffle indices in place using the provided RNG.
+pub fn shuffle_indices(indices: &mut [usize], rng: &mut SimpleRng) {
+    shuffle_items(indices, rng);
+}
diff --git a/src/rendering.rs b/src/rendering.rs
index 34007b4..f48ae07 100644
--- a/src/rendering.rs
+++ b/src/rendering.rs
@@ -4,6 +4,7 @@
  * and various markers using egui's Painter API.
  */
 
+use crate::exporter::utils::{corridor_edges_from_cells, room_edges_from_rooms};
 use crate::interact::{
     GridGeometry, HoverMarker, MarkerKind, cell_center, cell_rect, door_edges_for,
     door_render_width, marker_rect, normalized_edge, window_render_width,
@@ -496,46 +497,6 @@ pub fn draw_wall_segment(
     }
 }
 
-// Computes edges from cells.
-pub fn corridor_edges_from_cells(
-    corridor_cells: &HashSet<(usize, usize)>,
-) -> HashSet<((usize, usize), (usize, usize))> {
-    let mut edges = HashSet::new();
-    for &(col, row) in corridor_cells {
-        let right = (col + 1, row);
-        let bottom = (col, row + 1);
-        if corridor_cells.contains(&right) {
-            edges.insert(normalized_edge((col, row), right));
-        }
-        if corridor_cells.contains(&bottom) {
-            edges.insert(normalized_edge((col, row), bottom));
-        }
-    }
-    edges
-}
-
-// Computes edges from rooms.
-pub fn room_edges_from_rooms(
-    rooms: &[crate::layout::Room],
-) -> HashSet<((usize, usize), (usize, usize))> {
-    let mut edges = HashSet::new();
-    for room in rooms {
-        let x_end = room.x + room.width;
-        let y_end = room.y + room.height;
-        for x in room.x..x_end {
-            for y in room.y..y_end {
-                if x + 1 < x_end {
-                    edges.insert(normalized_edge((x, y), (x + 1, y)));
-                }
-                if y + 1 < y_end {
-                    edges.insert(normalized_edge((x, y), (x, y + 1)));
-                }
-            }
-        }
-    }
-    edges
-}
-
 #[derive(Debug, Clone, Copy)]
 pub enum DoorLineStyle {
     Solid,
diff --git a/src/ui/widgets.rs b/src/ui/widgets.rs
index 6dcc95a..6d62325 100644
--- a/src/ui/widgets.rs
+++ b/src/ui/widgets.rs
@@ -4,6 +4,9 @@
  *   and custom line styling (dashed, dotted, dash-dot patterns).
  */
 
+pub use crate::rendering::{
+    draw_dash_dot_dot_line, draw_dash_dot_line, draw_dashed_line, draw_dotted_line,
+};
 use eframe::egui;
 use egui::{Color32, Stroke};
 
@@ -167,124 +170,3 @@ pub fn draw_legend_entry_colorblind(ui: &mut egui::Ui, label: &str, style: Legen
     });
     ui.add_space(4.0);
 }
-
-// Draw a dashed line.
-pub fn draw_dashed_line(
-    painter: &egui::Painter,
-    from: egui::Pos2,
-    to: egui::Pos2,
-    stroke: Stroke,
-    dash_len: f32,
-    gap_len: f32,
-) {
-    let dx = to.x - from.x;
-    let dy = to.y - from.y;
-    let len = (dx * dx + dy * dy).sqrt();
-    if len <= 0.0 {
-        return;
-    }
-    let ux = dx / len;
-    let uy = dy / len;
-
-    let mut dist = 0.0_f32;
-    while dist < len {
-        let seg_start = dist;
-        let seg_end = (dist + dash_len).min(len);
-        let p0 = egui::pos2(from.x + ux * seg_start, from.y + uy * seg_start);
-        let p1 = egui::pos2(from.x + ux * seg_end, from.y + uy * seg_end);
-        painter.line_segment([p0, p1], stroke);
-        dist += dash_len + gap_len;
-    }
-}
-
-// Draw a dotted line.
-pub fn draw_dotted_line(painter: &egui::Painter, from: egui::Pos2, to: egui::Pos2, stroke: Stroke) {
-    let dx = to.x - from.x;
-    let dy = to.y - from.y;
-    let len = (dx * dx + dy * dy).sqrt();
-    if len <= 0.0 {
-        return;
-    }
-    let ux = dx / len;
-    let uy = dy / len;
-    let step = 5.0_f32;
-    let radius = (stroke.width * 0.35).max(1.0);
-
-    let mut dist = 0.0_f32;
-    while dist <= len {
-        let point = egui::pos2(from.x + ux * dist, from.y + uy * dist);
-        painter.circle_filled(point, radius, stroke.color);
-        dist += step;
-    }
-}
-
-// Draws dash dot line.
-pub fn draw_dash_dot_line(
-    painter: &egui::Painter,
-    from: egui::Pos2,
-    to: egui::Pos2,
-    stroke: Stroke,
-) {
-    let dx = to.x - from.x;
-    let dy = to.y - from.y;
-    let len = (dx * dx + dy * dy).sqrt();
-    if len <= 0.0 {
-        return;
-    }
-
-    let ux = dx / len;
-    let uy = dy / len;
-    let mut dist = 0.0_f32;
-    while dist < len {
-        let dash_end = (dist + 7.0).min(len);
-        let p0 = egui::pos2(from.x + ux * dist, from.y + uy * dist);
-        let p1 = egui::pos2(from.x + ux * dash_end, from.y + uy * dash_end);
-        painter.line_segment([p0, p1], stroke);
-        dist = dash_end + 3.0;
-        if dist >= len {
-            break;
-        }
-        let dot = egui::pos2(from.x + ux * dist, from.y + uy * dist);
-        painter.circle_filled(dot, (stroke.width * 0.35).max(1.0), stroke.color);
-        dist += 4.0;
-    }
-}
-
-// Draws dash dot dot line.
-pub fn draw_dash_dot_dot_line(
-    painter: &egui::Painter,
-    from: egui::Pos2,
-    to: egui::Pos2,
-    stroke: Stroke,
-) {
-    let dx = to.x - from.x;
-    let dy = to.y - from.y;
-    let len = (dx * dx + dy * dy).sqrt();
-    if len <= 0.0 {
-        return;
-    }
-
-    let ux = dx / len;
-    let uy = dy / len;
-    let radius = (stroke.width * 0.35).max(1.0);
-    let mut dist = 0.0_f32;
-    while dist < len {
-        let dash_end = (dist + 7.0).min(len);
-        let p0 = egui::pos2(from.x + ux * dist, from.y + uy * dist);
-        let p1 = egui::pos2(from.x + ux * dash_end, from.y + uy * dash_end);
-        painter.line_segment([p0, p1], stroke);
-        dist = dash_end + 3.0;
-        if dist >= len {
-            break;
-        }
-        let dot1 = egui::pos2(from.x + ux * dist, from.y + uy * dist);
-        painter.circle_filled(dot1, radius, stroke.color);
-        dist += 3.0;
-        if dist >= len {
-            break;
-        }
-        let dot2 = egui::pos2(from.x + ux * dist, from.y + uy * dist);
-        painter.circle_filled(dot2, radius, stroke.color);
-        dist += 4.0;
-    }
-}