diff --git a/crates/ui-egui/src/headless.rs b/crates/ui-egui/src/headless.rs
index e6929269..fdf5ecb6 100644
--- a/crates/ui-egui/src/headless.rs
+++ b/crates/ui-egui/src/headless.rs
@@ -170,6 +170,9 @@ pub struct Headless {
     pub view: HeadlessView,
     /// The largest texture the pretend GPU takes (what a WebGL device may report: 2048).
     pub max_texture_side: usize,
+    /// The limit egui was last told. Like a native host (egui-winit) it is reported once, not in
+    /// every frame's input: code that reads the raw input sees `None` from then on (issue #652).
+    reported_texture_side: Option<usize>,
     /// Logical size (points) and scale.
     pub size: egui::Vec2,
     pub pixels_per_point: f32,
@@ -201,6 +204,7 @@ impl Headless {
             app,
             view: HeadlessView::new(),
             max_texture_side: 16384,
+            reported_texture_side: None,
             size,
             pixels_per_point,
             time: 0.0,
@@ -227,7 +231,8 @@ impl Headless {
         (self.size, self.pixels_per_point) = bounded_viewport(self.size, self.pixels_per_point);
         let mut raw = HeadlessView::raw_input(self.size, self.pixels_per_point, self.time, std::mem::take(&mut self.events));
         raw.viewports.entry(ViewportId::ROOT).or_default().maximized = Some(self.window_maximized);
-        raw.max_texture_side = Some(self.max_texture_side);
+        raw.max_texture_side = (self.reported_texture_side != Some(self.max_texture_side)).then_some(self.max_texture_side);
+        self.reported_texture_side = Some(self.max_texture_side);
         self.app.raw_input_hook(&mut raw);
         let app = &mut self.app;
         let commands = self.view.run(raw, |ui| {
diff --git a/crates/ui-egui/src/panels/detail.rs b/crates/ui-egui/src/panels/detail.rs
index 2e708da6..cab305f0 100644
--- a/crates/ui-egui/src/panels/detail.rs
+++ b/crates/ui-egui/src/panels/detail.rs
@@ -187,10 +187,14 @@ pub(crate) fn navigate_gesture(app: &mut LightcraftApp, ui: &mut egui::Ui, resp:
     true
 }
 
-/// The largest texture the GPU behind `ctx` takes (egui reports it; 2048 when it doesn't, the
+/// The largest texture the GPU behind `ctx` takes (egui reports it; 2048 until it does, the
 /// smallest limit WebGL devices have).
+///
+/// The value egui keeps, not the frame's raw input: a native host (egui-winit) reports the limit
+/// in the first frame's input only, so the raw value is `None` from the second frame on
+/// (issue #652: every window render was cut to 2048 px, with blurry strips beside it).
 pub(crate) fn texture_side(ctx: &egui::Context) -> usize {
-    ctx.input(|i| i.raw.max_texture_side).unwrap_or(2048)
+    ctx.input(|i| i.max_texture_side)
 }
 
 /// The photo's own pixels as it is shown: its size after the crop and the user's rotation (what
@@ -2050,7 +2054,23 @@ fn straighten_overlay(app: &mut LightcraftApp, ui: &mut egui::Ui, resp: &egui::R
 
 #[cfg(test)]
 mod tests {
-    use super::film_label;
+    use super::{film_label, texture_side};
+
+    /// Issue #652: a native host reports the GPU's texture limit in the first frame's input only.
+    /// The loupe must still know it in every later frame (it read the raw input, found nothing and
+    /// cut every window render to 2048 px).
+    #[test]
+    fn the_texture_limit_outlives_the_frame_it_was_reported_in() {
+        let ctx = egui::Context::default();
+        assert_eq!(texture_side(&ctx), 2048, "until the host says: the smallest limit there is");
+        let mut seen = Vec::new();
+        for reported in [Some(8192), None, None] {
+            let raw = egui::RawInput { max_texture_side: reported, ..Default::default() };
+            let mut out = ctx.run_ui(raw, |ui| seen.push(texture_side(ui.ctx())));
+            out.textures_delta.clear();
+        }
+        assert_eq!(seen, [8192, 8192, 8192]);
+    }
 
     #[test]
     fn film_labels_cut_on_characters_not_bytes() {
diff --git a/crates/ui-egui/src/tests_preview_limit.rs b/crates/ui-egui/src/tests_preview_limit.rs
index 4b15cd17..f48a2e1c 100644
--- a/crates/ui-egui/src/tests_preview_limit.rs
+++ b/crates/ui-egui/src/tests_preview_limit.rs
@@ -352,6 +352,28 @@ mod in_the_loupe {
         }
     }
 
+    // Issue #652: given a canvas wider than 2048 px on a desktop GPU (which reports its texture
+    // limit to egui once, in the first frame), when I zoom to 1:1, then the window render covers
+    // the whole canvas: no strip of the magnified whole-frame render beside it
+    #[test]
+    fn a_window_covers_a_canvas_wider_than_2048_px() {
+        let (mut h, native) = detail_in([2600.0, 1200.0]);
+        assert!(native > 2600, "the photo is wider than the canvas at 1:1: {native}");
+        h.request("engine.execute", json!({"command": "view.zoom100"}), T);
+        h.settle(SETTLE);
+        let canvas = h.app.canvas_rect.expect("the loupe was drawn");
+        let image = h.app.image_rect.expect("the photo was drawn");
+        let region = h.app.region_view.expect("a window");
+        // the canvas in pixels of the window's frame (scale 1, at 100 %: a point is a pixel)
+        let to_px = region.full.0 as f32 / image.width();
+        let (left, right) = (to_px * (canvas.left() - image.left()), to_px * (canvas.right() - image.left()));
+        assert!(right - left > 2048.0, "the canvas shows more than 2048 px: {left}..{right}");
+        let (x0, x1) = (region.window.x as f32, (region.window.x + region.window.w) as f32);
+        assert!(x0 <= left + 0.5 && x1 >= right - 0.5, "the window {x0}..{x1} leaves part of the canvas {left}..{right} to the preview");
+        let (w, _) = region_tile(&h).expect("the window rendered");
+        assert_eq!(w, region.window.w, "and that is the texture drawn");
+    }
+
     // Given 400 % on a big photo, when a slider is dragged, then the work per frame follows the
     // canvas, not the zoom: a draft of the whole frame at canvas scale and a draft of the window
     #[test]