diff --git a/ROADMAP.md b/ROADMAP.md
index 0d4bdebd..22290e52 100644
--- a/ROADMAP.md
+++ b/ROADMAP.md
@@ -37,6 +37,7 @@
 > **Last reviewed:** 2026-10-10 · **Last updated:** 2026-10-12 · **Change:** minor (progress log for 2026-10-12; previous: minor, hours to ~95% per audience added; ready 56% → 55%; stage stays alpha; before that: major, full re-measure against PowerPoint for Mac 16.113.4; restructured to the craftrules progress-docs standard) · **Target:** Microsoft PowerPoint for Mac 16.113 (Microsoft 365)
 > **Last reviewed:** 2026-10-10 · **Last updated:** 2026-10-12 · **Change:** minor (progress log: table cell editing and border resizing; previous: minor, hours to ~95% per audience added; ready 56% → 55%; stage stays alpha) · **Target:** Microsoft PowerPoint for Mac 16.113 (Microsoft 365)
 > **Last reviewed:** 2026-10-10 · **Last updated:** 2026-10-11 · **Change:** minor (animated GIF export in the progress log, #171; P2 breadth 36% → 37%; previous: minor, hours to ~95% per audience added; ready 56% → 55%; stage stays alpha) · **Target:** Microsoft PowerPoint for Mac 16.113 (Microsoft 365)
+> **Last reviewed:** 2026-10-14 · **Last updated:** 2026-10-14 · **Change:** trivial (progress log: Format Background picture options; percentages unchanged) · **Target:** Microsoft PowerPoint for Mac 16.113 (Microsoft 365)
 
 DeckCraft aims at full PowerPoint parity, and to be better: faster, open (a documented zip+JSON
 format plus PPTX), scriptable by agents (CLI, JSON control channel, MCP), and available everywhere
@@ -214,6 +215,7 @@ app's JSON control channel (`deckcraft --control PORT`).
 | 2026-10-14 | Design ▸ Effects: named effect schemes (DeckCraft, Soft, Crisp, Lift, Glow, Plain) replace the theme's fills, lines and effects and leave colours and fonts. `design.effects` |
 | 2026-10-14 | Slide Master: Preserve on the open master or layout, and Title and Footers placeholder checkboxes. Two commands (`master.preserve`, `master.placeholders`); dialogs stay 27; breadth stays 79% |
 | 2026-10-14 | Trim Media: start, end and fades open from the selected clip, so OK no longer resets them to zero |
+| 2026-10-14 | Format Background: a solid fill's transparency, and for a picture transparency, tile, offset, scale, alignment and mirror. Apply to All copies a picture background onto every slide. The same `design.background` command; dialogs stay 27 |
 | 2026-10-13 | Slide transitions like PowerPoint: every transition and option measured frame by frame against PowerPoint's video export and retuned (curves, directions, soft edges, 3-D perspective, contents moving over backgrounds); PowerPoint's own XML elements and defaults read and written (diagonal Wipe, Zoom, Shape In/Out, Glitter Hexagons, Shred In/Out, Page Curl Single); `deckcraft-cli render-transition` renders frames headless |
 | 2026-10-13 | Wild text cases measured against PowerPoint (102 synthetic slides): bidi by run language, East Asian vertical text upright, mongolianVert/wordArtVert/wordArtVertRtl, underline styles and strikethrough at the font's metrics, centre/right/decimal tabs, East Asian, Thai, Hindi, Arabic and Hebrew numbering, small caps, all-caps "ß", transparent text, soft hyphens, kinsoku, rtlCol and just/dist anchoring, emoji presentation, fallback faces that no longer move the baseline |
 | 2026-10-13 | Render matches PowerPoint more closely on wild shape, picture and table cases: even-odd custom paths, dashes and caps, arrowheads, radial and path gradients, tile rects, rotWithShape, gradient lines, shadows cast by what is drawn (group and perspective too), group fill, picture borders, tiles, reflection, recolour (biLevel, alphaInv, brightness/contrast), table borders and grid default, 20+ preset shapes by their ECMA formulas, default miter joins, and approximate 3-D bevels, cameras and face lighting |
@@ -285,6 +287,7 @@ app's JSON control channel (`deckcraft --control PORT`).
 | 2026-10-14 | trivial | Progress log: Design ▸ Effects |
 | 2026-10-14 | trivial | Progress log: Slide Master Preserve and Title/Footers placeholders. Percentages unchanged |
 | 2026-10-14 | trivial | Progress log: Trim Media dialog follows the selection |
+| 2026-10-14 | trivial | Progress log: Format Background picture and solid options |
 | 2026-10-13 | trivial | Progress log: wild text cases |
 | 2026-10-13 | trivial | Progress log: slide show for interactive decks |
 | 2026-10-12 | minor | Progress log: table cell editing and border resizing |
diff --git a/crates/engine/src/cmd/design.rs b/crates/engine/src/cmd/design.rs
index 626002c1..7ced659f 100644
--- a/crates/engine/src/cmd/design.rs
+++ b/crates/engine/src/cmd/design.rs
@@ -41,7 +41,7 @@ pub fn specs() -> Vec<CommandSpec> {
             "Format Background",
             ["Design", "Customize"],
             None,
-            "{color? | gradient? | picture?: base64 | style?: 1..12 | reset?, all?: bool (apply to all), index?}",
+            "{color? | gradient? | picture?: base64 | pattern? | style?: 1..12 | reset?, all?: bool, index?, transparency?: 0..1, pictureProps?: {tile?, offsetX?, offsetY?: pt, scaleX?, scaleY?: 0.01..10, align?, mirror?, stretch?: [l,t,r,b], rotateWithShape?}, copy?: bool}",
             has_slide,
             background
         ),
@@ -452,70 +452,256 @@ fn effects(s: &mut Session, p: &Value) -> Result<Value> {
 }
 
 fn background(s: &mut Session, p: &Value) -> Result<Value> {
-    let bg: Option<Background> = if bool_or(p, "reset", false) {
-        None
-    } else if let Some(c) = color_param(p, "color") {
-        Some(Background::Fill { fill: Fill::solid(c) })
-    } else if let Some(i) = usize_param(p, "style") {
+    if bool_or(p, "copy", false) {
+        return copy_slide_background(s);
+    }
+    let props = p.get("pictureProps").filter(|v| v.is_object()).cloned();
+    let transparency = f64_param(p, "transparency");
+    let reset = bool_or(p, "reset", false);
+    let color = color_param(p, "color");
+    let style = usize_param(p, "style");
+    let op = if reset {
+        BgOp::Set(None)
+    } else if let Some(mut c) = color {
+        if let Some(t) = transparency {
+            set_solid_transparency(&mut c, t);
+        }
+        BgOp::Set(Some(Background::Fill { fill: Fill::solid(c) }))
+    } else if let Some(i) = style {
         // Background styles: 3 theme bg fills × 4 colours (bg1, bg2, tx1, tx2).
         let slots =
             [deckcraft_color::SchemeSlot::Bg1, deckcraft_color::SchemeSlot::Bg2, deckcraft_color::SchemeSlot::Tx2, deckcraft_color::SchemeSlot::Tx1];
         let i = i.clamp(1, 12) - 1;
-        Some(Background::Ref {
+        BgOp::Set(Some(Background::Ref {
             idx: 1001 + (i / 4) as u32,
             color: deckcraft_model::ColorRef::scheme(slots.get(i % 4).copied().unwrap_or(deckcraft_color::SchemeSlot::Bg1)),
-        })
+        }))
     } else if let Some(g) = p.get("gradient") {
         let mut g = super::shape::gradient_param(g).ok_or_else(|| bad("design.background", "gradient needs two or more `stops`"))?;
         g.rotate_with_shape = false;
-        Some(Background::Fill { fill: Fill::Gradient(g) })
+        BgOp::Set(Some(Background::Fill { fill: Fill::Gradient(g) }))
     } else if let Some(pt) = p.get("pattern") {
-        Some(Background::Fill {
+        BgOp::Set(Some(Background::Fill {
             fill: Fill::Pattern(deckcraft_model::style::PatternFill {
                 preset: pt.get("preset").and_then(Value::as_str).unwrap_or("pct50").to_string(),
                 fg: pt.get("fg").and_then(color_value).unwrap_or(deckcraft_model::ColorRef::scheme(deckcraft_color::SchemeSlot::Accent1)),
                 bg: pt.get("bg").and_then(color_value).unwrap_or(deckcraft_model::ColorRef::scheme(deckcraft_color::SchemeSlot::Bg1)),
             }),
-        })
+        }))
     } else if p.get("picture").is_some() {
         let (name, bytes) = super::insert::media_bytes(&with_param(p, "data", p.get("picture").cloned().unwrap_or_default()), "design.background")?;
         let ct = super::insert::content_type(&name, &bytes);
         let media = s.edit(|doc, _| Ok(doc.add_media(&name, ct, bytes)))?;
-        Some(Background::Fill { fill: Fill::Picture(deckcraft_model::style::PictureFill { media, ..Default::default() }) })
+        let mut pf = deckcraft_model::style::PictureFill { media, ..Default::default() };
+        if let Some(pp) = &props {
+            apply_picture_props(&mut pf, pp);
+        }
+        if let Some(t) = transparency {
+            set_picture_transparency(&mut pf, t);
+        }
+        BgOp::Set(Some(Background::Fill { fill: Fill::Picture(pf) }))
+    } else if props.is_some() || transparency.is_some() {
+        BgOp::Adjust
     } else {
-        return Err(bad("design.background", "give `color`, `gradient`, `pattern`, `picture`, `style` or `reset`"));
+        return Err(bad(
+            "design.background",
+            "give `color`, `gradient`, `pattern`, `picture`, `style`, `reset`, `pictureProps`, `transparency` or `copy`",
+        ));
     };
     let all = bool_or(p, "all", false);
     let index = usize_param(p, "index");
+    if matches!(op, BgOp::Adjust) {
+        let next = {
+            let st = s.doc()?;
+            let current = background_of(&st.doc, &st.selection, index);
+            let picture = matches!(current, Some(Background::Fill { fill: Fill::Picture(_) }));
+            let solid = matches!(current, Some(Background::Fill { fill: Fill::Solid { .. } }));
+            if props.is_some() && !picture {
+                return Err(bad("design.background", "picture options need a picture background"));
+            }
+            if transparency.is_some() && !picture && !solid {
+                return Err(bad("design.background", "transparency needs a solid or picture background"));
+            }
+            let mut next = current.clone();
+            if let Some(bg) = next.as_mut() {
+                adjust_background(bg, props.as_ref(), transparency);
+            }
+            if next == current { None } else { Some(next) }
+        };
+        let Some(next) = next else { return ok() };
+        s.edit(|doc, sel| {
+            write_background(doc, sel, index, false, next);
+            Ok(())
+        })?;
+        return ok();
+    }
+    let BgOp::Set(bg) = op else { return ok() };
+    let unchanged = {
+        let st = s.doc()?;
+        backgrounds_already(&st.doc, &st.selection, index, all, &bg)
+    };
+    if unchanged {
+        return ok();
+    }
     s.edit(|doc, sel| {
-        match sel.target {
-            Target::Master { master } => {
-                if let Some(m) = doc.masters.get_mut(master) {
-                    Arc::make_mut(m).background = bg.clone();
+        write_background(doc, sel, index, all, bg);
+        Ok(())
+    })?;
+    ok()
+}
+
+enum BgOp {
+    Set(Option<Background>),
+    Adjust,
+}
+
+fn background_of(doc: &Presentation, sel: &crate::Selection, index: Option<usize>) -> Option<Background> {
+    match sel.target {
+        Target::Master { master } => doc.masters.get(master).and_then(|m| m.background.clone()),
+        Target::Layout { master, layout } => doc.masters.get(master).and_then(|m| m.layouts.get(layout)).and_then(|l| l.background.clone()),
+        t @ (Target::Handout | Target::NotesMaster) => crate::page_master(doc, t).and_then(|m| m.background.clone()),
+        Target::Slides => doc.slides.get(index.unwrap_or(sel.slide)).and_then(|sl| sl.background.clone()),
+    }
+}
+
+fn backgrounds_already(doc: &Presentation, sel: &crate::Selection, index: Option<usize>, all: bool, bg: &Option<Background>) -> bool {
+    match sel.target {
+        Target::Master { master } => doc.masters.get(master).is_some_and(|m| m.background == *bg),
+        Target::Layout { master, layout } => doc.masters.get(master).and_then(|m| m.layouts.get(layout)).is_some_and(|l| l.background == *bg),
+        t @ (Target::Handout | Target::NotesMaster) => crate::page_master(doc, t).is_some_and(|m| m.background == *bg),
+        Target::Slides => {
+            let list: Vec<usize> = if all { (0..doc.slides.len()).collect() } else { vec![index.unwrap_or(sel.slide)] };
+            !list.is_empty() && list.iter().all(|i| doc.slides.get(*i).is_some_and(|sl| sl.background == *bg))
+        }
+    }
+}
+
+fn write_background(doc: &mut Presentation, sel: &crate::Selection, index: Option<usize>, all: bool, bg: Option<Background>) {
+    match sel.target {
+        Target::Master { master } => {
+            if let Some(m) = doc.masters.get_mut(master) {
+                Arc::make_mut(m).background = bg;
+            }
+        }
+        Target::Layout { master, layout } => {
+            if let Some(l) = doc.masters.get_mut(master).and_then(|m| Arc::make_mut(m).layouts.get_mut(layout)) {
+                l.background = bg;
+            }
+        }
+        t @ (Target::Handout | Target::NotesMaster) => {
+            if let Some(m) = crate::page_master_mut(doc, t) {
+                Arc::make_mut(m).background = bg;
+            }
+        }
+        Target::Slides => {
+            let list: Vec<usize> = if all { (0..doc.slides.len()).collect() } else { vec![index.unwrap_or(sel.slide)] };
+            for i in list {
+                if let Some(sl) = doc.slides.get_mut(i) {
+                    Arc::make_mut(sl).background = bg.clone();
                 }
             }
-            Target::Layout { master, layout } => {
-                if let Some(l) = doc.masters.get_mut(master).and_then(|m| Arc::make_mut(m).layouts.get_mut(layout)) {
-                    l.background = bg.clone();
-                }
+        }
+    }
+}
+
+fn copy_slide_background(s: &mut Session) -> Result<Value> {
+    let bg = {
+        let st = s.doc()?;
+        if !matches!(st.selection.target, Target::Slides) {
+            return Err(bad("design.background", "copy applies to slides"));
+        }
+        let bg = st.doc.slides.get(st.selection.slide).and_then(|sl| sl.background.clone());
+        if st.doc.slides.iter().all(|sl| sl.background == bg) {
+            return ok();
+        }
+        bg
+    };
+    s.edit(|doc, sel| {
+        write_background(doc, sel, None, true, bg);
+        Ok(())
+    })?;
+    ok()
+}
+
+fn adjust_background(bg: &mut Background, props: Option<&Value>, transparency: Option<f64>) {
+    match bg {
+        Background::Fill { fill: Fill::Picture(pf) } => {
+            if let Some(pp) = props {
+                apply_picture_props(pf, pp);
             }
-            t @ (Target::Handout | Target::NotesMaster) => {
-                if let Some(m) = crate::page_master_mut(doc, t) {
-                    Arc::make_mut(m).background = bg.clone();
-                }
+            if let Some(t) = transparency {
+                set_picture_transparency(pf, t);
             }
-            Target::Slides => {
-                let list: Vec<usize> = if all { (0..doc.slides.len()).collect() } else { vec![index.unwrap_or(sel.slide)] };
-                for i in list {
-                    if let Some(sl) = doc.slides.get_mut(i) {
-                        Arc::make_mut(sl).background = bg.clone();
+        }
+        Background::Fill { fill: Fill::Solid { color } } => {
+            if let Some(t) = transparency {
+                set_solid_transparency(color, t);
+            }
+        }
+        _ => {}
+    }
+}
+
+fn set_picture_transparency(pf: &mut deckcraft_model::style::PictureFill, t: f64) {
+    let a = 1.0 - t.clamp(0.0, 1.0);
+    pf.alpha = (a < 1.0).then_some(a);
+}
+
+fn set_solid_transparency(color: &mut deckcraft_model::ColorRef, t: f64) {
+    color.mods.retain(|m| !matches!(m, deckcraft_color::ColorTransform::Alpha(_)));
+    let t = t.clamp(0.0, 1.0);
+    if t > 0.0 {
+        color.mods.push(deckcraft_color::ColorTransform::Alpha(((1.0 - t) * 100_000.0).round() as i32));
+    }
+}
+
+/// Picture-fill options for Format Background (tile, offsets, scale, alignment, mirror, stretch).
+fn apply_picture_props(pf: &mut deckcraft_model::style::PictureFill, pp: &Value) {
+    use deckcraft_model::style::PictureMode;
+    let f = |k: &str| pp.get(k).and_then(Value::as_f64).filter(|v| v.is_finite());
+    if let Some(up) = pp.get("rotateWithShape").and_then(Value::as_bool) {
+        pf.upright = !up;
+    }
+    match pp.get("tile").and_then(Value::as_bool) {
+        Some(true) if !matches!(pf.mode, PictureMode::Tile { .. }) => {
+            pf.mode = PictureMode::Tile { tx: 0.0, ty: 0.0, sx: 1.0, sy: 1.0, flip: "none".into(), align: "tl".into() };
+        }
+        Some(false) if !matches!(pf.mode, PictureMode::Stretch { .. }) => pf.mode = PictureMode::default(),
+        _ => {}
+    }
+    match &mut pf.mode {
+        PictureMode::Tile { tx, ty, sx, sy, flip, align } => {
+            if let Some(v) = f("offsetX") {
+                *tx = v.clamp(-4000.0, 4000.0);
+            }
+            if let Some(v) = f("offsetY") {
+                *ty = v.clamp(-4000.0, 4000.0);
+            }
+            if let Some(v) = f("scaleX") {
+                *sx = v.clamp(0.01, 10.0);
+            }
+            if let Some(v) = f("scaleY") {
+                *sy = v.clamp(0.01, 10.0);
+            }
+            if let Some(m) = pp.get("mirror").and_then(Value::as_str).filter(|m| matches!(*m, "none" | "x" | "y" | "xy")) {
+                *flip = m.to_string();
+            }
+            if let Some(a) =
+                pp.get("align").and_then(Value::as_str).filter(|a| matches!(*a, "tl" | "t" | "tr" | "l" | "ctr" | "r" | "bl" | "b" | "br"))
+            {
+                *align = a.to_string();
+            }
+        }
+        PictureMode::Stretch { fill_rect } => {
+            if let Some(arr) = pp.get("stretch").and_then(Value::as_array) {
+                for (slot, v) in fill_rect.iter_mut().zip(arr) {
+                    if let Some(v) = v.as_f64().filter(|v| v.is_finite()) {
+                        *slot = v.clamp(-10.0, 0.99);
                     }
                 }
             }
         }
-        Ok(())
-    })?;
-    ok()
+    }
 }
 
 fn hide_bg_graphics(s: &mut Session, p: &Value) -> Result<Value> {
@@ -1238,7 +1424,9 @@ fn slide_number_paragraph() -> deckcraft_model::Paragraph {
 #[cfg(test)]
 mod tests {
     use deckcraft_color::SchemeSlot;
+    use deckcraft_model::style::PictureMode;
     use deckcraft_model::theme::{FontScheme, ScriptFont, builtin_color_schemes, builtin_font_schemes};
+    use deckcraft_model::{Background, Fill};
     use serde_json::{Value, json};
 
     use crate::{Session, UiRequest};
@@ -1255,6 +1443,21 @@ mod tests {
         s.doc().unwrap().history.undo.len()
     }
 
+    fn png() -> String {
+        let mut img = image::RgbaImage::new(2, 2);
+        img.put_pixel(0, 0, image::Rgba([10, 20, 30, 255]));
+        let mut bytes = Vec::new();
+        image::DynamicImage::ImageRgba8(img).write_to(&mut std::io::Cursor::new(&mut bytes), image::ImageFormat::Png).unwrap();
+        crate::cmd::base64_encode(&bytes)
+    }
+
+    fn picture(s: &Session) -> deckcraft_model::style::PictureFill {
+        match &s.doc().unwrap().doc.slides[0].background {
+            Some(Background::Fill { fill: Fill::Picture(pf) }) => pf.clone(),
+            other => panic!("expected a picture background, got {other:?}"),
+        }
+    }
+
     #[test]
     fn civil_dates() {
         assert_eq!(super::civil(0), (1970, 1, 1));
@@ -1425,6 +1628,72 @@ mod tests {
         assert_eq!(font_scheme(&s).major.ea, "Kept");
         assert_eq!(font_scheme(&s).minor.latin, "Open Sans");
     }
+
+    #[test]
+    fn background_picture_options_tile_transparency_and_copy() {
+        let mut s = Session::with_new();
+        let n = undo_len(&s);
+        let err = s.execute("design.background", &json!({"pictureProps": {"tile": true}})).unwrap_err().to_string();
+        assert!(err.contains("picture background"), "{err}");
+        assert!(s.execute("design.background", &json!({"transparency": 0.2})).is_err());
+        assert_eq!(undo_len(&s), n);
+
+        s.execute("design.background", &json!({"color": "accent1", "transparency": 0.25})).unwrap();
+        match &s.doc().unwrap().doc.slides[0].background {
+            Some(Background::Fill { fill: Fill::Solid { color } }) => assert!((color.alpha() - 0.75).abs() < 1e-4, "{}", color.alpha()),
+            other => panic!("expected a solid background, got {other:?}"),
+        }
+        let n = undo_len(&s);
+        s.execute("design.background", &json!({"transparency": 0.25})).unwrap();
+        assert_eq!(undo_len(&s), n, "the same transparency is not an undo step");
+
+        s.execute("design.background", &json!({"picture": png(), "name": "dot.png", "transparency": 0.4, "pictureProps": {"tile": true}})).unwrap();
+        let pf = picture(&s);
+        assert!((pf.alpha.unwrap_or(1.0) - 0.6).abs() < 1e-6);
+        assert!(matches!(pf.mode, PictureMode::Tile { .. }));
+        let n = undo_len(&s);
+
+        s.execute(
+            "design.background",
+            &json!({"pictureProps": {"offsetX": 12.0, "offsetY": -3.0, "scaleX": 0.5, "scaleY": 50.0, "align": "ctr", "mirror": "xy", "rotateWithShape": false}}),
+        )
+        .unwrap();
+        match picture(&s).mode {
+            PictureMode::Tile { tx, ty, sx, sy, flip, align } => {
+                assert_eq!((tx, ty, sx, sy), (12.0, -3.0, 0.5, 10.0));
+                assert_eq!(flip, "xy");
+                assert_eq!(align, "ctr");
+            }
+            other => panic!("expected a tile, got {other:?}"),
+        }
+        assert!(picture(&s).upright);
+        s.execute("design.background", &json!({"pictureProps": {"align": "bogus", "offsetX": "nope"}})).unwrap();
+        match picture(&s).mode {
+            PictureMode::Tile { tx, align, .. } => {
+                assert_eq!(tx, 12.0);
+                assert_eq!(align, "ctr");
+            }
+            other => panic!("expected the tile to stay, got {other:?}"),
+        }
+        assert_eq!(undo_len(&s), n + 1, "ignored options are not an undo step");
+
+        s.execute("design.background", &json!({"pictureProps": {"tile": false, "stretch": [0.1, 0.2, 0.0, 0.0]}})).unwrap();
+        match picture(&s).mode {
+            PictureMode::Stretch { fill_rect } => assert_eq!(fill_rect, [0.1, 0.2, 0.0, 0.0]),
+            other => panic!("expected a stretch, got {other:?}"),
+        }
+
+        s.execute("slide.new", &json!({})).unwrap();
+        assert!(s.doc().unwrap().doc.slides[1].background.is_none());
+        s.execute("slide.go", &json!({"index": 0})).unwrap();
+        let n = undo_len(&s);
+        s.execute("design.background", &json!({"copy": true})).unwrap();
+        assert_eq!(s.doc().unwrap().doc.slides[1].background, s.doc().unwrap().doc.slides[0].background);
+        assert_eq!(undo_len(&s), n + 1);
+        assert_eq!(s.doc().unwrap().history.undo.last().unwrap().label, "Format Background");
+        s.execute("design.background", &json!({"copy": true})).unwrap();
+        assert_eq!(undo_len(&s), n + 1, "copying an already shared background is not an undo step");
+    }
 }
 
 #[cfg(test)]
diff --git a/crates/ui-egui/src/background_tests.rs b/crates/ui-egui/src/background_tests.rs
new file mode 100644
index 00000000..b2a7a879
--- /dev/null
+++ b/crates/ui-egui/src/background_tests.rs
@@ -0,0 +1,75 @@
+//! Format Background pane: picture transparency, tiling, and Apply to All.
+
+use deckcraft_engine::Session;
+use deckcraft_model::style::PictureMode;
+use deckcraft_model::{Background, Fill};
+use egui_kittest::Harness;
+use egui_kittest::kittest::Queryable;
+use serde_json::json;
+
+use crate::{Services, SlideApp};
+
+/// 1×1 PNG.
+const PNG: &str = "iVBORw0KGgoAAAANSUhEUgAAAAEAAAABCAYAAAAfFcSJAAAADUlEQVR42mP8z8BQDwAEhQGAhKmMIQAAAABJRU5ErkJggg==";
+
+fn harness(mut app: SlideApp) -> Harness<'static, SlideApp> {
+    app.ui.tab = "Design".into();
+    app.ui.pane = Some("background".into());
+    let mut h = Harness::builder().with_size(egui::vec2(1800.0, 1100.0)).build_ui_state(
+        |ui, app: &mut SlideApp| {
+            app.logic(ui.ctx());
+            app.ui(ui);
+        },
+        app,
+    );
+    h.run_steps(3);
+    h
+}
+
+fn picture_mode(h: &Harness<'_, SlideApp>) -> PictureMode {
+    match &h.state().session.active().unwrap().doc.slides[0].background {
+        Some(Background::Fill { fill: Fill::Picture(pf) }) => pf.mode.clone(),
+        other => panic!("expected a picture background, got {other:?}"),
+    }
+}
+
+#[test]
+fn picture_fill_shows_transparency_and_tiling() {
+    let mut s = Session::with_new();
+    s.execute("design.background", &json!({"picture": PNG, "name": "dot.png"})).unwrap();
+    let mut h = harness(SlideApp::new(s, Services::default()));
+    let _ = h.get_by_label("Format Background");
+    let _ = h.get_by_label("Picture or texture fill");
+    assert!(h.query_all_by_label("Transparency").next().is_some());
+    h.get_by_label("Tile picture as texture").click();
+    h.run_steps(2);
+    let _ = h.get_by_label("Offset X");
+    let _ = h.get_by_label("Scale X");
+    let _ = h.get_by_label("Alignment");
+    let _ = h.get_by_label("Mirror");
+    assert!(matches!(picture_mode(&h), PictureMode::Tile { .. }));
+}
+
+#[test]
+fn solid_fill_shows_transparency_without_tile_options() {
+    let mut s = Session::with_new();
+    s.execute("design.background", &json!({"color": "accent1"})).unwrap();
+    let h = harness(SlideApp::new(s, Services::default()));
+    assert!(h.query_all_by_label("Transparency").next().is_some());
+    let _ = h.get_by_label("Solid fill");
+    assert!(h.query_by_label("Tile picture as texture").is_none());
+}
+
+#[test]
+fn apply_to_all_copies_the_picture() {
+    let mut s = Session::with_new();
+    s.execute("design.background", &json!({"picture": PNG, "name": "dot.png"})).unwrap();
+    s.execute("slide.new", &json!({})).unwrap();
+    s.execute("slide.go", &json!({"index": 0})).unwrap();
+    let mut h = harness(SlideApp::new(s, Services::default()));
+    h.get_by_label("Apply to All").click();
+    h.run_steps(2);
+    let doc = &h.state().session.active().unwrap().doc;
+    assert!(matches!(doc.slides[1].background, Some(Background::Fill { fill: Fill::Picture(_) })));
+    assert_eq!(doc.slides[1].background, doc.slides[0].background);
+}
diff --git a/crates/ui-egui/src/panes.rs b/crates/ui-egui/src/panes.rs
index 6225753a..bb9d4021 100644
--- a/crates/ui-egui/src/panes.rs
+++ b/crates/ui-egui/src/panes.rs
@@ -652,6 +652,10 @@ fn background(app: &mut SlideApp, ui: &mut Ui) {
                     }
                 });
             });
+            let mut tr = ((1.0 - color.alpha()) * 100.0) as f32;
+            if ui.add(egui::Slider::new(&mut tr, 0.0..=100.0).text("Transparency").suffix("%")).drag_stopped() {
+                run(app, "design.background", json!({"transparency": (f64::from(tr) / 100.0).clamp(0.0, 1.0)}));
+            }
         }
         Some(Fill::Gradient(g)) => {
             current = Some(json!({"gradient": crate::fillui::gradient_json(g)}));
@@ -681,7 +685,7 @@ fn background(app: &mut SlideApp, ui: &mut Ui) {
                 });
             }
         }
-        Some(Fill::Picture(_)) => {
+        Some(Fill::Picture(pf)) => {
             if ui.button("Insert picture from file…").clicked()
                 && let Some(pick) = app.services.pick_open.as_mut()
                 && let Some(path) = pick("picture")
@@ -689,6 +693,7 @@ fn background(app: &mut SlideApp, ui: &mut Ui) {
             {
                 let _ = app.run("design.background", json!({"picture": deckcraft_engine::cmd::base64_encode(&bytes)}));
             }
+            picture_background_options(app, ui, pf);
         }
         _ => {}
     }
@@ -699,12 +704,15 @@ fn background(app: &mut SlideApp, ui: &mut Ui) {
         run(app, "design.hideBackgroundGraphics", json!({"hide": h}));
     }
     ui.add_space(8.0);
+    let picture = matches!(fill, Some(Fill::Picture(_)));
     ui.horizontal(|ui| {
-        if ui.add_enabled(current.is_some(), egui::Button::new("Apply to All")).clicked()
-            && let Some(Value::Object(mut o)) = current.clone()
-        {
-            o.insert("all".into(), json!(true));
-            run(app, "design.background", Value::Object(o));
+        if ui.add_enabled(current.is_some() || picture, egui::Button::new("Apply to All")).clicked() {
+            if let Some(Value::Object(mut o)) = current.clone() {
+                o.insert("all".into(), json!(true));
+                run(app, "design.background", Value::Object(o));
+            } else if picture {
+                run(app, "design.background", json!({"copy": true}));
+            }
         }
         if ui.button("Reset Background").clicked() {
             run(app, "design.background", json!({"reset": true}));
@@ -712,6 +720,86 @@ fn background(app: &mut SlideApp, ui: &mut Ui) {
     });
 }
 
+fn picture_background_options(app: &mut SlideApp, ui: &mut Ui, pf: &deckcraft_model::style::PictureFill) {
+    use deckcraft_model::style::PictureMode;
+    let alpha = pf.alpha.unwrap_or(1.0);
+    let mut tr = ((1.0 - alpha) * 100.0) as f32;
+    if ui.add(egui::Slider::new(&mut tr, 0.0..=100.0).text("Transparency").suffix("%")).drag_stopped() {
+        run(app, "design.background", json!({"transparency": (f64::from(tr) / 100.0).clamp(0.0, 1.0)}));
+    }
+    let mut tile = matches!(pf.mode, PictureMode::Tile { .. });
+    if ui.checkbox(&mut tile, "Tile picture as texture").changed() {
+        run(app, "design.background", json!({"pictureProps": {"tile": tile}}));
+    }
+    let PictureMode::Tile { tx, ty, sx, sy, flip, align } = &pf.mode else { return };
+    for (label, id, value, suffix, scale) in [
+        ("Offset X", "bg-ox", *tx, " pt", 1.0),
+        ("Offset Y", "bg-oy", *ty, " pt", 1.0),
+        ("Scale X", "bg-sx", *sx * 100.0, "%", 0.01),
+        ("Scale Y", "bg-sy", *sy * 100.0, "%", 0.01),
+    ] {
+        ui.horizontal(|ui| {
+            ui.add_sized(vec2(72.0, 20.0), egui::Label::new(label));
+            if let Some(v) = widgets::spinner(ui, id, value, if scale < 1.0 { 5.0 } else { 1.0 }, suffix, 64.0) {
+                let key = match id {
+                    "bg-ox" => "offsetX",
+                    "bg-oy" => "offsetY",
+                    "bg-sx" => "scaleX",
+                    _ => "scaleY",
+                };
+                run(app, "design.background", json!({"pictureProps": {key: v * scale}}));
+            }
+        });
+    }
+    let align_name = match align.as_str() {
+        "t" => "Top",
+        "tr" => "Top Right",
+        "l" => "Left",
+        "ctr" => "Center",
+        "r" => "Right",
+        "bl" => "Bottom Left",
+        "b" => "Bottom",
+        "br" => "Bottom Right",
+        _ => "Top Left",
+    };
+    ui.horizontal(|ui| {
+        ui.add_sized(vec2(72.0, 20.0), egui::Label::new("Alignment"));
+        egui::ComboBox::from_id_salt("bg-align").selected_text(align_name).width(140.0).show_ui(ui, |ui| {
+            for (k, l) in [
+                ("tl", "Top Left"),
+                ("t", "Top"),
+                ("tr", "Top Right"),
+                ("l", "Left"),
+                ("ctr", "Center"),
+                ("r", "Right"),
+                ("bl", "Bottom Left"),
+                ("b", "Bottom"),
+                ("br", "Bottom Right"),
+            ] {
+                if ui.selectable_label(align == k, l).clicked() {
+                    run(app, "design.background", json!({"pictureProps": {"align": k}}));
+                }
+            }
+        });
+    });
+    let mirror_name = match flip.as_str() {
+        "x" => "Horizontal",
+        "y" => "Vertical",
+        "xy" => "Both",
+        _ => "None",
+    };
+    ui.horizontal(|ui| {
+        ui.add_sized(vec2(72.0, 20.0), egui::Label::new("Mirror"));
+        egui::ComboBox::from_id_salt("bg-mirror").selected_text(mirror_name).width(140.0).show_ui(ui, |ui| {
+            for (k, l) in [("none", "None"), ("x", "Horizontal"), ("y", "Vertical"), ("xy", "Both")] {
+                if ui.selectable_label(flip == k, l).clicked() {
+                    run(app, "design.background", json!({"pictureProps": {"mirror": k}}));
+                }
+            }
+        });
+    });
+}
+
 fn animation(app: &mut SlideApp, ui: &mut Ui) {
     let t = Tokens::get(ui.ctx());
     let Some(st) = app.session.active() else { return };
@@ -1088,3 +1176,7 @@ pub(crate) fn text_transparency_slider(app: &mut SlideApp, ui: &mut Ui, sh: &dec
 #[cfg(test)]
 #[path = "smartart_tests.rs"]
 mod smartart_tests;
+
+#[cfg(test)]
+#[path = "background_tests.rs"]
+mod background_tests;
diff --git a/docs/gaps.md b/docs/gaps.md
index 46cabed3..7d23dc99 100644
--- a/docs/gaps.md
+++ b/docs/gaps.md
@@ -26,6 +26,7 @@
 > **Last reviewed:** 2026-10-14 · **Last updated:** 2026-10-14 · **Change:** minor (Slide Master Preserve and Title/Footers placeholders; checklist letters unchanged, breadth stays 79%, dialogs stay 27; previous: 3-D bevel, camera and face lighting rendered) · **Target:** Microsoft PowerPoint for Mac 16.113 (Microsoft 365)
 > **Last reviewed:** 2026-10-14 · **Last updated:** 2026-10-14 · **Change:** minor (chart trendlines are drawn; previous: minor, chart trendlines round-trip; 3-D bevel, camera and face lighting rendered; IME composition and CJK interface text landed, #101; core-workflow alpha gate added; stage stays alpha; full re-measure against PowerPoint for Mac 16.113.4 and the open GitHub issues) · **Target:** Microsoft PowerPoint for Mac 16.113 (Microsoft 365)
 > **Last reviewed:** 2026-10-10 · **Last updated:** 2026-10-11 · **Change:** minor (animated GIF export landed, #171; the video gap stays; previous: minor, core-workflow alpha gate added; stage stays alpha) · **Target:** Microsoft PowerPoint for Mac 16.113 (Microsoft 365)
+> **Last reviewed:** 2026-10-14 · **Last updated:** 2026-10-14 · **Change:** minor (Format Background picture options are pane controls, not a new dialog; dialogs stay 27; previous: 3-D bevel, camera and face lighting rendered) · **Target:** Microsoft PowerPoint for Mac 16.113 (Microsoft 365)
 
 Every known shortfall, one entry each, ranked by how much it stops someone who presents with
 PowerPoint from switching. This is the work list: pick from the top. Numbers are summarized in
@@ -357,6 +358,10 @@ Detail in [ui-parity.md](ui-parity.md).
   Action Settings, Print, Insert Object…). 8–14 h.
 - **Dialogs**: 30 dialogs vs PowerPoint's ~60 (Font, Find/Replace dialog, Replace Fonts, Print,
   Insert Object…). Size and Position, Bullets and Numbering, Action Settings and Date and Time are in. 8–14 h.
+- **Dialogs**: 27 dialogs vs PowerPoint's ~60 (Font, Bullets and Numbering, Find/Replace dialog,
+  Replace Fonts, Action Settings, Print, Insert Object…). Format Background picture options
+  (transparency, tile, offset, scale, alignment, mirror, and Apply to All copying a picture) are
+  pane controls on `design.background`, not another dialog. 8–14 h.
 - **Command palette defaults to an Export entry that fails** (#79). 0.5 h.
 
 ## Hardware
@@ -450,6 +455,7 @@ Detail in [localization-parity.md](localization-parity.md).
 | 2026-10-13 | trivial | Command palette skips commands that need a value, so Export opens the dialog (#79) |
 | 2026-10-14 | minor | Design ▸ Effects applies a named effect scheme. The checklist row stays P, so breadth stays 79%. Dialogs stay 27 |
 | 2026-10-14 | minor | Slide Master Preserve and Title/Footers placeholders. Checklist letters unchanged (breadth stays 79%); dialogs stay 27 |
+| 2026-10-14 | minor | Format Background picture and solid options are in the existing pane. Dialogs stay 27 |
 | 2026-10-13 | minor | Shape, picture and table rendering checked against PowerPoint on ~150 synthetic edge-case slides; 3-D bevels, cameras and face lighting now render approximately (gap narrowed to extrusion, rigs and the 3-D pane) |
 | 2026-10-13 | minor | Interactive decks: triggers, return-to-slide state and click rules landed in the slide show; the remaining pieces are one new entry under Features |
 | 2026-10-12 | minor | IME composition in slide text and notes, and CJK interface text with real glyphs (#101): the IME gap is now Korean on the web and table-cell underlines |
diff --git a/docs/target-app-parity.md b/docs/target-app-parity.md
index 9a7c421e..0319ca9c 100644
--- a/docs/target-app-parity.md
+++ b/docs/target-app-parity.md
@@ -18,6 +18,7 @@
 > **Last reviewed:** 2026-10-14 · **Last updated:** 2026-10-14 · **Change:** minor (Design ▸ Effects; percentages unchanged; previous: hours to ~95% per audience, ready ~55%) · **Target:** Microsoft PowerPoint for Mac 16.113 (Microsoft 365)
 > **Last reviewed:** 2026-10-14 · **Last updated:** 2026-10-14 · **Change:** minor (Slide Master Preserve and Title/Footers; automation counted at 236 commands; the menu measurement and the d556ff9 snapshot still count 226; percentages unchanged; previous: hours to ~95% per audience, ready 56% → 55%) · **Target:** Microsoft PowerPoint for Mac 16.113 (Microsoft 365)
 > **Last reviewed:** 2026-10-10 · **Last updated:** 2026-10-11 · **Change:** minor (animated GIF export, #171: P2 breadth 36% → 37%, overall unchanged; previous: minor, hours to ~95% per audience added; ready recomputed from written weights, 56% → 55%; stage stays alpha) · **Target:** Microsoft PowerPoint for Mac 16.113 (Microsoft 365)
+> **Last reviewed:** 2026-10-14 · **Last updated:** 2026-10-14 · **Change:** minor (Format Background picture and solid options; percentages unchanged; previous: hours to ~95% per audience, ready ~55%) · **Target:** Microsoft PowerPoint for Mac 16.113 (Microsoft 365)
 
 The authoritative answer to "how close is DeckCraft to PowerPoint, and how much work is left?".
 [ROADMAP.md](../ROADMAP.md) summarizes it; [gaps.md](gaps.md) itemizes every shortfall;
@@ -243,6 +244,9 @@ Carried from the 2026-10-07 ROADMAP status and updated with what has landed sinc
   Asian or complex-script faces).
   effect schemes (Design ▸ Effects: DeckCraft, Soft, Crisp, Lift, Glow, Plain),
   backgrounds (solid, gradient, picture, pattern), slide size presets.
+  backgrounds (solid, gradient, picture, pattern; a solid fill's transparency; picture
+  transparency, tile, offset, scale, alignment and mirror; Apply to All copies a picture),
+  slide size presets.
 - **Shapes:** ~180 preset geometries with adjustment handles, text boxes, pictures (crop,
   corrections, animated GIFs that play and pause), tables with styles, charts (column, bar, line,
   area, pie, doughnut, scatter and more), basic SmartArt, groups, connectors glued to sites,
@@ -343,6 +347,7 @@ scored done (16 open issues).
 | 2026-10-14 | minor | Design ▸ Effects noted under what works today. Percentages stay 79% / ~60% / ~55%. The d556ff9 snapshot and the menu measurement stay at 226 commands; the live registry is 227 |
 | 2026-10-14 | minor | Slide Master Preserve and Title/Footers placeholders. Automation in "what works today" is 236 commands; the menu-bar measurement and the d556ff9 snapshot still count 226. Percentages unchanged |
 | 2026-10-11 | minor | Animated GIF export (#171) moves the checklist's video/GIF row from missing to partial: P2 breadth 36% → 37%; overall breadth (79%), dimension scores and stage unchanged |
+| 2026-10-14 | minor | Format Background picture and solid options noted under what works today. Percentages, the 226-command count and the d556ff9 dialog snapshot stay as they are |
 | 2026-10-10 | minor | Added the readiness-by-audience table: each number gets its own hours to ~95% (full 340–600, mainstream 150–250, essentials 50–90). The full number stays an additive weighted sum; no change to the percentages |
 | 2026-10-10 | minor | Added the mainstream practitioner (~53%) and essentials user (~62%) numbers with written weights, discounts and user evidence. Features dimension recomputed from written area weights (66% judgement → 62.4% weighted mean), which moves ready for real work from ~56% to ~55%; stage unchanged |
 | 2026-10-10 | minor | Stage checked against the core-workflow gate (all six pass); stays alpha |
diff --git a/docs/ui-parity.md b/docs/ui-parity.md
index ee5933c3..89399702 100644
--- a/docs/ui-parity.md
+++ b/docs/ui-parity.md
@@ -22,6 +22,7 @@
 > **Last reviewed:** 2026-10-14 · **Last updated:** 2026-10-14 · **Change:** trivial (Trim Media dialog follows the selection; previous: File tab / Backstage, #76) · **Target:** Microsoft PowerPoint for Mac 16.113 (Microsoft 365)
 > **Last reviewed:** 2026-10-10 · **Last updated:** 2026-10-12 · **Change:** minor (the frame of a text box being edited moves it; previous: minor, File tab / Backstage, #76) · **Target:** Microsoft PowerPoint for Mac 16.113 (Microsoft 365)
 > **Last reviewed:** 2026-10-10 · **Last updated:** 2026-10-12 · **Change:** minor (table cells: caret, clicks between cells, border resizing; previous: minor, File tab / Backstage, #76) · **Target:** Microsoft PowerPoint for Mac 16.113 (Microsoft 365)
+> **Last reviewed:** 2026-10-14 · **Last updated:** 2026-10-14 · **Change:** minor (Format Background picture and solid options; dialogs stay 27) · **Target:** Microsoft PowerPoint for Mac 16.113 (Microsoft 365)
 
 > **Last reviewed:** 2026-10-12 · **Last updated:** 2026-10-14 · **Change:** minor (File › New starter decks; previous: minor, text editing keys observed in PowerPoint for Windows, #268) · **Target:** Microsoft PowerPoint for Mac 16.113 (Microsoft 365)
 > **Last reviewed:** 2026-10-14 · **Last updated:** 2026-10-14 · **Change:** minor (Slide Sorter sections: add, rename, collapse, drag a whole section; previous: text editing keys, #268) · **Target:** Microsoft PowerPoint for Mac 16.113 (Microsoft 365)
@@ -30,6 +31,7 @@
 > **Last reviewed:** 2026-10-14 · **Last updated:** 2026-10-14 · **Change:** minor (Insert › Date and Time dialog; previous: text editing keys, #268) · **Target:** Microsoft PowerPoint for Mac 16.113 (Microsoft 365)
 > **Last reviewed:** 2026-10-14 · **Last updated:** 2026-10-14 · **Change:** minor (Design ▸ Effects; dialogs stay 27) · **Target:** Microsoft PowerPoint for Mac 16.113 (Microsoft 365)
 > **Last reviewed:** 2026-10-14 · **Last updated:** 2026-10-14 · **Change:** minor (Slide Master Preserve and Title/Footers placeholders; previous: text editing keys observed in PowerPoint for Windows, #268) · **Target:** Microsoft PowerPoint for Mac 16.113 (Microsoft 365)
+> **Last reviewed:** 2026-10-14 · **Last updated:** 2026-10-14 · **Change:** minor (Format Background picture and solid options; dialogs stay 27) · **Target:** Microsoft PowerPoint for Mac 16.113 (Microsoft 365)
 
 How DeckCraft looks and feels next to PowerPoint: the shell, the ribbon, menus, panes, dialogs,
 direct manipulation, keyboard and precision. Observations of PowerPoint are kept locally in
@@ -92,6 +94,8 @@ menu colours taken from the theme tokens (menu `chrome`, page `card`).
 | Format Shape / Picture / Text pane (Fill & Line, Effects, Size & Properties, Picture, Text Box) | full | partial: fill, gradient editor, line, shadow/glow/reflection details (colour, transparency, blur, angle, distance, size), soft edges, size; no 3-D, thin picture/texture options |
 | Format Background pane | yes | yes |
 | Slide Master | Insert Layout, Rename, Delete, Preserve, Insert Placeholder, Title and Footers | Insert Layout, Rename, Delete, Insert Placeholder, and Preserve, Title and Footers checkboxes (`master.preserve`, `master.placeholders`). A master thumbnail selects the master |
+| Format Shape / Picture / Text pane (Fill & Line, Effects, Size & Properties, Picture, Text Box) | full | partial: fill, gradient editor, line, some effects, size; no 3-D, thin picture/texture options |
+| Format Background pane | yes | yes: solid transparency; picture transparency, tile, offset, scale, alignment and mirror; Apply to All copies a picture. Stretch insets and rotate-with-shape are command parameters |
 | Selection Pane | front-most first, groups fold, drag to restack, Bring Forward / Send Backward arrows, Show All / Hide All, eye, padlock (Lock), rename in place | same: drag restacks among siblings (a child stays in its group), Ctrl+click toggles, Shift+click selects a run, arrows / Home / End / F2 / Esc in the list, right-click menu |
 | Animation Pane | list + advanced timeline | list, reorder, timing; no timeline |
 | Comments pane (threads) | yes | yes: every slide, with Previous and Next on the Review tab |
@@ -227,6 +231,7 @@ on the slide as shapes. No pixel comparison against PowerPoint screenshots has b
 | 2026-10-14 | trivial | Trim Media dialog: start, end and fades follow the selected clip |
 | 2026-10-12 | minor | Dragging the frame of a text box being edited moves it, as in PowerPoint |
 | 2026-10-12 | minor | Table cells: caret and selection shown in the edited cell, clicks place the caret in the clicked cell, row and column borders drag to resize |
+| 2026-10-14 | minor | Format Background pane: solid transparency, picture transparency, tile, offset, scale, alignment, mirror, and Apply to All copying a picture. Not a new dialog; the dialog count stays 27 |
 | 2026-10-12 | minor | File tab (Backstage) observed in PowerPoint for Windows and matched (#76); the start screen is File › Home |
 | 2026-10-12 | minor | Off-slide objects drawn and editable around the slide in Normal view (#270) |
 | 2026-10-12 | minor | Selection Pane matched to PowerPoint (#133): drag and drop, arrows, groups, eye, Lock |