Release 0.10.0

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

Cargo.lock

@@ -892,7 +892,7 @@ checksum = "0c87e182de0887fd5361989c677c4e8f5000cd9491d6d563161a8f3a5519fc7f"
 
 [[package]]
 name = "deckcraft"
-version = "0.9.0"
+version = "0.10.0"
 dependencies = [
  "arboard",
  "cpal",
@@ -912,7 +912,7 @@ dependencies = [
 
 [[package]]
 name = "deckcraft-anim"
-version = "0.9.0"
+version = "0.10.0"
 dependencies = [
  "deckcraft-geom",
  "deckcraft-model",
@@ -921,7 +921,7 @@ dependencies = [
 
 [[package]]
 name = "deckcraft-av1"
-version = "0.9.0"
+version = "0.10.0"
 dependencies = [
  "deckcraft-bitstream",
  "rayon",
@@ -930,14 +930,14 @@ dependencies = [
 
 [[package]]
 name = "deckcraft-bitstream"
-version = "0.9.0"
+version = "0.10.0"
 dependencies = [
  "proptest",
 ]
 
 [[package]]
 name = "deckcraft-cli"
-version = "0.9.0"
+version = "0.10.0"
 dependencies = [
  "deckcraft-engine",
  "deckcraft-mcp",
@@ -947,14 +947,14 @@ dependencies = [
 
 [[package]]
 name = "deckcraft-color"
-version = "0.9.0"
+version = "0.10.0"
 dependencies = [
  "serde",
 ]
 
 [[package]]
 name = "deckcraft-engine"
-version = "0.9.0"
+version = "0.10.0"
 dependencies = [
  "deckcraft-anim",
  "deckcraft-color",
@@ -979,7 +979,7 @@ dependencies = [
 
 [[package]]
 name = "deckcraft-fonts"
-version = "0.9.0"
+version = "0.10.0"
 dependencies = [
  "epaint_default_fonts",
  "harfrust 0.13.3",
@@ -991,7 +991,7 @@ dependencies = [
 
 [[package]]
 name = "deckcraft-format"
-version = "0.9.0"
+version = "0.10.0"
 dependencies = [
  "deckcraft-model",
  "serde",
@@ -1002,7 +1002,7 @@ dependencies = [
 
 [[package]]
 name = "deckcraft-geom"
-version = "0.9.0"
+version = "0.10.0"
 dependencies = [
  "kurbo",
  "serde",
@@ -1010,7 +1010,7 @@ dependencies = [
 
 [[package]]
 name = "deckcraft-h264"
-version = "0.9.0"
+version = "0.10.0"
 dependencies = [
  "deckcraft-bitstream",
  "rayon",
@@ -1019,7 +1019,7 @@ dependencies = [
 
 [[package]]
 name = "deckcraft-hevc"
-version = "0.9.0"
+version = "0.10.0"
 dependencies = [
  "deckcraft-bitstream",
  "rayon",
@@ -1028,7 +1028,7 @@ dependencies = [
 
 [[package]]
 name = "deckcraft-isobmff"
-version = "0.9.0"
+version = "0.10.0"
 dependencies = [
  "deckcraft-bitstream",
  "thiserror 2.0.21",
@@ -1036,11 +1036,11 @@ dependencies = [
 
 [[package]]
 name = "deckcraft-matroska"
-version = "0.9.0"
+version = "0.10.0"
 
 [[package]]
 name = "deckcraft-mcp"
-version = "0.9.0"
+version = "0.10.0"
 dependencies = [
  "deckcraft-engine",
  "deckcraft-render",
@@ -1050,7 +1050,7 @@ dependencies = [
 
 [[package]]
 name = "deckcraft-media"
-version = "0.9.0"
+version = "0.10.0"
 dependencies = [
  "deckcraft-av1",
  "deckcraft-h264",
@@ -1068,7 +1068,7 @@ dependencies = [
 
 [[package]]
 name = "deckcraft-metafile"
-version = "0.9.0"
+version = "0.10.0"
 dependencies = [
  "image",
  "kurbo",
@@ -1077,7 +1077,7 @@ dependencies = [
 
 [[package]]
 name = "deckcraft-model"
-version = "0.9.0"
+version = "0.10.0"
 dependencies = [
  "deckcraft-color",
  "deckcraft-geom",
@@ -1089,15 +1089,15 @@ dependencies = [
 
 [[package]]
 name = "deckcraft-ogg"
-version = "0.9.0"
+version = "0.10.0"
 
 [[package]]
 name = "deckcraft-opus"
-version = "0.9.0"
+version = "0.10.0"
 
 [[package]]
 name = "deckcraft-pdf"
-version = "0.9.0"
+version = "0.10.0"
 dependencies = [
  "craft-pdf",
  "deckcraft-fonts",
@@ -1115,7 +1115,7 @@ dependencies = [
 
 [[package]]
 name = "deckcraft-pptx"
-version = "0.9.0"
+version = "0.10.0"
 dependencies = [
  "deckcraft-color",
  "deckcraft-engine",
@@ -1131,7 +1131,7 @@ dependencies = [
 
 [[package]]
 name = "deckcraft-render"
-version = "0.9.0"
+version = "0.10.0"
 dependencies = [
  "deckcraft-anim",
  "deckcraft-color",
@@ -1150,7 +1150,7 @@ dependencies = [
 
 [[package]]
 name = "deckcraft-text"
-version = "0.9.0"
+version = "0.10.0"
 dependencies = [
  "chrono",
  "deckcraft-color",
@@ -1164,7 +1164,7 @@ dependencies = [
 
 [[package]]
 name = "deckcraft-ui-egui"
-version = "0.9.0"
+version = "0.10.0"
 dependencies = [
  "deckcraft-anim",
  "deckcraft-color",
@@ -1186,7 +1186,7 @@ dependencies = [
 
 [[package]]
 name = "deckcraft-vp9"
-version = "0.9.0"
+version = "0.10.0"
 dependencies = [
  "deckcraft-bitstream",
  "rayon",
@@ -1195,7 +1195,7 @@ dependencies = [
 
 [[package]]
 name = "deckcraft-web"
-version = "0.9.0"
+version = "0.10.0"
 dependencies = [
  "deckcraft-engine",
  "deckcraft-ui-egui",
@@ -5733,7 +5733,7 @@ checksum = "9440ea3e5aeabb0ac63af70daf835274065238cdd0cec83418f417eae38bacee"
 
 [[package]]
 name = "xtask"
-version = "0.9.0"
+version = "0.10.0"
 dependencies = [
  "serde_json",
 ]

Cargo.toml

@@ -4,7 +4,7 @@ members = ["crates/*", "apps/*", "xtask"]
 default-members = ["crates/*", "apps/deckcraft", "apps/deckcraft-cli"]
 
 [workspace.package]
-version = "0.9.0"
+version = "0.10.0"
 edition = "2024"
 license = "MIT OR Apache-2.0"
 rust-version = "1.95"

README.md

@@ -7,6 +7,10 @@
   </a>
 </p>
 
+<p align="center">
+  <img src="assets/app-icon/hicolor/256x256/apps/ai.storyteller.deckcraft.png" width="128" height="128" alt="DeckCraft icon: a presentation screen with a bar chart on an orange tile">
+</p>
+
 <h1 align="center">DeckCraft</h1>
 
 <p align="center">

ROADMAP.md

@@ -132,6 +132,7 @@ app's JSON control channel (`deckcraft --control PORT`).
 | Date | What landed |
 |---|---|
 | 2026-10-18 | Native chart sidecar bytes move from JSON arrays into referenced ZIP entries, with shared media byte/item limits and bounded reads; older inline sidecars still load. Synthetic format regressions cover large workbooks and malformed members |
+| 2026-10-18 | Slide thumbnails and the Slide Sorter render only the slides in view: on a deck of more than 600 slides they used to evict their own thumbnails, so the pane flashed white and never finished (#969) |
 | 2026-10-17 | Opening a file caps absurd effect sizes (glow, soft edges, shadows, reflections, on shapes, text and table text) at what Format Shape allows: a glow of 10^18 pt in a .pptx made rendering ask for 34 GB and abort |
 | 2026-10-17 | Opening a .deckcraft file whose shapes repeat an id gives the repeats fresh ids (groups, layouts and masters too), so the deck validates and edits by id find one shape |
 | 2026-10-17 | Edit Points: turning a shape into a freeform is one undo step, so Undo brings the original shape back (it used to stay a freeform) |
@@ -242,6 +243,7 @@ app's JSON control channel (`deckcraft --control PORT`).
 |---|---|---|
 | 2026-10-18 | minor | Native chart payloads use referenced ZIP members and share media byte/item limits; old inline sidecars remain readable. Synthetic tests cover multi-megabyte layout, all shape owners, shared budgets, missing/corrupt members and invalid references. Scores and milestone scope unchanged |
 | 2026-10-15 | trivial | Progress log: chart package parts survive a native save. Scores and milestone names unchanged |
+| 2026-10-18 | trivial | Progress log: thumbnails of huge decks render only the slides in view (#969) |
 | 2026-10-15 | trivial | Progress log: PPTX trigger click-step round trip. Feature scores and milestone names unchanged |
 | 2026-10-16 | trivial | Progress log: PNG export with a transparent background (#784) |
 | 2026-10-16 | trivial | Progress log: a `.ppsx` from the system starts the slide show (#862) |

crates/engine/src/cmd/animation.rs

@@ -525,4 +525,46 @@ mod tests {
         s.execute("animation.painterApply", &json!({"ids": [id3]})).unwrap();
         assert!(s.anim_painter.is_some());
     }
+
+    fn setup_triggers() -> (Session, [u64; 4]) {
+        let mut s = Session::with_new();
+        let mut ids = [0u64; 4];
+        for (slot, x) in ids.iter_mut().zip([10.0, 150.0, 300.0, 450.0]) {
+            let r = s.execute("shape.insert", &json!({"preset": "rect", "rect": [x, 10.0, 100.0, 100.0]})).unwrap();
+            *slot = r.get("id").unwrap().as_u64().unwrap();
+        }
+        (s, ids)
+    }
+
+    fn triggers(s: &Session) -> Vec<Option<deckcraft_model::ShapeId>> {
+        s.doc().unwrap().current_slide().unwrap().animations.iter().map(|x| x.trigger).collect()
+    }
+
+    #[test]
+    fn deleting_a_trigger_shape_clears_the_trigger() {
+        let (mut s, [a, b, c, d]) = setup_triggers();
+        let id = |v: u64| Some(deckcraft_model::ShapeId(v as u32));
+        s.execute("animation.add", &json!({"effect": "fade", "ids": [a]})).unwrap();
+        s.execute("animation.add", &json!({"effect": "fade", "ids": [d]})).unwrap();
+        s.execute("animation.timing", &json!({"index": 0, "trigger": b})).unwrap();
+        s.execute("animation.timing", &json!({"index": 1, "trigger": c})).unwrap();
+        assert_eq!(triggers(&s), vec![id(b), id(c)]);
+
+        s.execute("edit.delete", &json!({"ids": [b]})).unwrap();
+        assert_eq!(triggers(&s), vec![None, id(c)], "only the deleted trigger is cleared");
+        assert_eq!(s.doc().unwrap().current_slide().unwrap().animations.len(), 2, "the animated shapes keep their effects");
+    }
+
+    #[test]
+    fn deleting_a_group_clears_triggers_of_its_children() {
+        let (mut s, [a, b, c, _]) = setup_triggers();
+        let g = s.execute("arrange.group", &json!({"ids": [b, c]})).unwrap().get("id").unwrap().as_u64().unwrap();
+        s.execute("animation.add", &json!({"effect": "fade", "ids": [a]})).unwrap();
+        s.execute("animation.timing", &json!({"index": 0, "trigger": b})).unwrap();
+        assert_eq!(triggers(&s), vec![Some(deckcraft_model::ShapeId(b as u32))]);
+
+        s.execute("edit.delete", &json!({"ids": [g]})).unwrap();
+        assert_eq!(triggers(&s), vec![None], "the trigger was inside the deleted group");
+        assert_eq!(s.doc().unwrap().current_slide().unwrap().animations.len(), 1);
+    }
 }

crates/engine/src/cmd/edit.rs

@@ -572,12 +572,24 @@ fn delete(s: &mut Session, p: &Value) -> Result<Value> {
     }
     s.edit(|doc, sel| {
         let shapes = crate::shapes_mut(doc, sel).ok_or_else(|| bad("edit.delete", "no slide"))?;
+        let mut before = Vec::new();
+        deckcraft_model::walk(shapes, &mut |s, _| before.push(s.id));
         let n = remove_shapes(shapes, &ids);
+        // Everything that is gone: the given ids plus group descendants and emptied groups.
+        let mut left = Vec::new();
+        deckcraft_model::walk(shapes, &mut |s, _| left.push(s.id));
+        let mut gone = ids.clone();
+        gone.extend(before.into_iter().filter(|i| !left.contains(i)));
         // Animations of deleted shapes go too.
         if sel.target == crate::Target::Slides
             && let Some(sl) = doc.slides.get_mut(sel.slide)
         {
-            Arc::make_mut(sl).animations.retain(|a| !ids.contains(&a.shape));
+            let sl = Arc::make_mut(sl);
+            sl.animations.retain(|a| !gone.contains(&a.shape));
+            // Effects triggered by a deleted shape fall back to the main sequence.
+            for a in sl.animations.iter_mut().filter(|a| a.trigger.is_some_and(|t| gone.contains(&t))) {
+                a.trigger = None;
+            }
         }
         sel.shapes.retain(|i| !ids.contains(i));
         sel.text = None;

crates/engine/src/cmd/mod.rs

@@ -318,6 +318,14 @@ pub(crate) fn str_param<'a>(p: &'a Value, key: &str) -> Option<&'a str> {
 pub(crate) fn usize_param(p: &Value, key: &str) -> Option<usize> {
     p.get(key).and_then(Value::as_u64).and_then(|v| usize::try_from(v).ok())
 }
+/// An index param: `Ok(None)` when absent (callers may fall back to the selection), `Err` when
+/// present but not a valid index (negative, non-integer), so a bad index never acts on the selection.
+pub(crate) fn opt_usize_param(p: &Value, key: &str, cmd: &str) -> Result<Option<usize>> {
+    match p.get(key) {
+        None | Some(Value::Null) => Ok(None),
+        Some(v) => v.as_u64().and_then(|v| usize::try_from(v).ok()).map(Some).ok_or_else(|| bad(cmd, format!("`{key}` is not a valid index: {v}"))),
+    }
+}
 /// A shape id param: `Ok(None)` when absent (callers may fall back to the selection), `Err` when
 /// present but not a valid id (negative, non-integer, beyond `u32`), so a bad id never edits the selection.
 pub(crate) fn id_param(p: &Value, key: &str, cmd: &str) -> Result<Option<ShapeId>> {

crates/engine/src/cmd/slide.rs

@@ -179,7 +179,7 @@ fn body_placeholder(shapes: &mut [deckcraft_model::Shape]) -> Option<&mut deckcr
 
 fn index_of(s: &Session, p: &Value) -> Result<usize> {
     let st = s.doc()?;
-    let i = usize_param(p, "index").unwrap_or(st.selection.slide);
+    let i = opt_usize_param(p, "index", "slide")?.unwrap_or(st.selection.slide);
     if i >= st.doc.slides.len() {
         return Err(bad("slide", format!("no slide {i}")));
     }
@@ -187,7 +187,7 @@ fn index_of(s: &Session, p: &Value) -> Result<usize> {
 }
 
 fn duplicate(s: &mut Session, p: &Value) -> Result<Value> {
-    let indices: Vec<usize> = match usize_param(p, "index") {
+    let indices: Vec<usize> = match opt_usize_param(p, "index", "slide.duplicate")? {
         Some(i) => vec![i],
         None => {
             let st = s.doc()?;
@@ -240,7 +240,7 @@ fn delete(s: &mut Session, p: &Value) -> Result<Value> {
         let st = s.doc()?;
         if let Some(a) = p.get("ids").and_then(Value::as_array) {
             a.iter().filter_map(Value::as_u64).filter_map(|v| u32::try_from(v).ok()).map(SlideId).collect()
-        } else if let Some(i) = usize_param(p, "index") {
+        } else if let Some(i) = opt_usize_param(p, "index", "slide.delete")? {
             st.doc.slides.get(i).map(|x| vec![x.id]).unwrap_or_default()
         } else if !st.selection.slides.is_empty() {
             st.selection.slides.clone()
@@ -266,7 +266,7 @@ fn delete(s: &mut Session, p: &Value) -> Result<Value> {
 }
 
 fn move_slide(s: &mut Session, p: &Value) -> Result<Value> {
-    let from = usize_param(p, "from").unwrap_or(s.doc()?.selection.slide);
+    let from = opt_usize_param(p, "from", "slide.move")?.unwrap_or(s.doc()?.selection.slide);
     let to = usize_param(p, "to").ok_or_else(|| bad("slide.move", "missing `to`"))?;
     s.edit(|doc, sel| {
         if from >= doc.slides.len() {
@@ -531,7 +531,7 @@ fn rename(s: &mut Session, p: &Value) -> Result<Value> {
 }
 
 fn section_add(s: &mut Session, p: &Value) -> Result<Value> {
-    let at = usize_param(p, "at").unwrap_or(s.doc()?.selection.slide);
+    let at = opt_usize_param(p, "at", "section.add")?.unwrap_or(s.doc()?.selection.slide);
     let name = str_param(p, "name").unwrap_or("Untitled Section").to_string();
     s.edit(|doc, _| {
         let at = at.min(doc.slides.len().saturating_sub(1));
@@ -648,6 +648,25 @@ mod tests {
 
     use crate::Session;
 
+    #[test]
+    fn invalid_index_params_are_rejected_not_defaulted_to_selection() {
+        let mut s = Session::with_new();
+        while s.doc().expect("doc").doc.slides.len() < 3 {
+            s.execute("slide.new", &json!({})).expect("new slide");
+        }
+        for bad in [json!(-1), json!(1.5)] {
+            for (cmd, p) in [
+                ("slide.delete", json!({"index": bad})),
+                ("slide.duplicate", json!({"index": bad})),
+                ("slide.move", json!({"from": bad, "to": 0})),
+                ("section.add", json!({"at": bad})),
+            ] {
+                assert!(s.execute(cmd, &p).is_err(), "{cmd} must reject {p}");
+                assert_eq!(s.doc().expect("doc").doc.slides.len(), 3, "{cmd} {p}");
+            }
+        }
+    }
+
     #[test]
     fn duplicate_keeps_section_order_in_step_with_slides() {
         let mut s = Session::with_new();

crates/engine/src/recovery.rs

@@ -44,6 +44,11 @@ pub fn instance_id() -> u64 {
     *ID.get_or_init(|| {
         use std::hash::{BuildHasher, Hasher};
         let mut h = std::collections::hash_map::RandomState::new().build_hasher();
+        // No PIDs and no std::time on wasm (`std::process::id()` and
+        // `SystemTime::now()` panic there): the browser clock stands in.
+        #[cfg(target_arch = "wasm32")]
+        h.write_u64(js_sys::Date::now() as u64);
+        #[cfg(not(target_arch = "wasm32"))]
         h.write_u32(std::process::id());
         #[cfg(not(target_arch = "wasm32"))]
         if let Ok(d) = std::time::SystemTime::now().duration_since(std::time::UNIX_EPOCH) {

crates/pptx/src/opc.rs

@@ -281,8 +281,8 @@ fn percent_decode(s: &str) -> String {
 
 /// Resolve a relative target against a base directory into a part name.
 pub fn resolve(base: &str, target: &str) -> String {
-    let target = percent_decode(target);
-    let target = target.split('#').next().unwrap_or("");
+    let target = percent_decode(target.split('#').next().unwrap_or(""));
+    let target = target.as_str();
     let mut segs: Vec<&str> = if target.starts_with('/') { vec![] } else { base.split('/').filter(|s| !s.is_empty()).collect() };
     for s in target.split('/') {
         match s {
@@ -441,6 +441,12 @@ impl PackageOut {
 mod tests {
     use super::*;
 
+    #[test]
+    fn resolve_keeps_encoded_hash_and_strips_fragment() {
+        assert_eq!(resolve("ppt/slides", "../media/a%23b.png"), "ppt/media/a#b.png");
+        assert_eq!(resolve("ppt/slides", "../media/a.png#frag"), "ppt/media/a.png");
+    }
+
     fn zip_of(entries: &[(&str, usize)]) -> Vec<u8> {
         let mut zw = zip::ZipWriter::new(Cursor::new(Vec::new()));
         let o = zip::write::SimpleFileOptions::default().compression_method(zip::CompressionMethod::Deflated);

crates/text/src/lib.rs

@@ -413,6 +413,9 @@ struct ParaShaped {
     /// Size of the paragraph's first run (spacing percentages, empty lines).
     lead_size: f64,
     lead_face: Arc<FontFace>,
+    /// Size of the paragraph mark (`a:endParaRPr`): what an empty last line is sized by.
+    end_size: f64,
+    end_face: Arc<FontFace>,
     bullet: Option<(String, Style)>,
     #[allow(dead_code)]
     level: u8,
@@ -709,7 +712,9 @@ fn shape_para(ctx: &Ctx, shape: &Shape, body: &TextBody, pi: usize, scale: f64,
             faces: vec![],
             props: ParaProps::default(),
             lead_size: 18.0,
-            lead_face: face,
+            lead_face: face.clone(),
+            end_size: 18.0,
+            end_face: face,
             bullet: None,
             level: 0,
             rtl: false,
@@ -741,6 +746,9 @@ fn shape_para(ctx: &Ctx, shape: &Shape, body: &TextBody, pi: usize, scale: f64,
     let lead_style = make_style(ctx, &lead, scale, opts.prompt_color);
     let lead_size = lead_style.size;
     let lead_face = lead_style.face.clone();
+    // The paragraph mark, which ends the last line when no break does.
+    let end_style = make_style(ctx, &resolve::run(ctx, shape, para, &para.end_props), scale, opts.prompt_color);
+    let (end_size, end_face) = (end_style.size, end_style.face.clone());
     // Bullet.
     let bullet = match &props.bullet {
         Some(Bullet::Char { char }) => {
@@ -789,7 +797,7 @@ fn shape_para(ctx: &Ctx, shape: &Shape, body: &TextBody, pi: usize, scale: f64,
         }
         _ => None,
     };
-    ParaShaped { cells, styles, faces, props, lead_size, lead_face, bullet, level: para.level, rtl }
+    ParaShaped { cells, styles, faces, props, lead_size, lead_face, end_size, end_face, bullet, level: para.level, rtl }
 }
 
 /// A face that draws the bullet `label` when the bullet's own can't (circled numbers ①, arrows
@@ -1712,10 +1720,21 @@ fn layout_scaled(ctx: &Ctx, shape: &Shape, body: &TextBody, bp: &BodyProps, opts
                 }
             }
             if size == 0.0 {
-                let (a, d) = line_metrics(&p.lead_face, p.lead_size);
+                // PowerPoint sizes an empty line by the mark that ends it: the `a:rPr` of the
+                // `a:br` that closes it, or `a:endParaRPr` for the paragraph's last line -- not
+                // by the paragraph's first run (#780). An empty *paragraph* already lands on
+                // `end_props` through `lead`, and keeps the same height here.
+                let brk = p.cells.get(rl.end).filter(|c| c.ch == '\u{b}').and_then(|c| p.styles.get(c.style));
+                let (face, sz) = match brk {
+                    Some(st) => (&st.face, st.size),
+                    None if rl.end >= p.cells.len() => (&p.end_face, p.end_size),
+                    // Anything else empty (a line of tabs alone) keeps the old measure.
+                    None => (&p.lead_face, p.lead_size),
+                };
+                let (a, d) = line_metrics(face, sz);
                 asc = a;
                 desc = d;
-                size = p.lead_size;
+                size = sz;
             }
             let natural = (asc + desc).max(size * 1.0);
             let lh = match props.line_spacing {

crates/text/src/tests.rs

@@ -1467,3 +1467,99 @@ fn empty_plain_paragraphs_and_soft_breaks_have_no_bullet_preview() {
     assert_eq!(l.lines.len(), 2);
     assert!(l.empty_bullets.is_empty(), "a soft line break is not a new list item");
 }
+
+/// A run of `text` at `size` points.
+fn sized_run(text: &str, size: f64) -> Run {
+    let mut r = Run::new(text);
+    r.props.size = Some(size);
+    r
+}
+
+/// A line break whose own run properties are `size` points.
+fn sized_break(size: f64) -> Run {
+    let mut r = Run { text: String::new(), props: Default::default(), kind: deckcraft_model::text::RunKind::Break };
+    r.props.size = Some(size);
+    r
+}
+
+/// The height one line of `size`-point text takes in this shape: the yardstick the empty-line
+/// tests measure against, so they do not depend on the test font's ascent and descent.
+fn one_line_height(p: &Presentation, sh: &mut Shape, size: f64) -> f64 {
+    sh.text.as_mut().unwrap().paragraphs = vec![Paragraph { runs: vec![sized_run("X", size)], ..Default::default() }];
+    let l = lay(p, sh, 400.0, 400.0);
+    l.lines[0].bottom - l.lines[0].top
+}
+
+#[test]
+fn an_empty_line_is_sized_by_the_break_that_ends_it() {
+    // PowerPoint sizes an empty line by the mark that closes it, not by the paragraph's first
+    // run (#780). Case A of the report: 40pt text, a 40pt break, a 10pt break, 40pt text, so
+    // the empty second line is a 10pt line and not a 40pt one.
+    let (p, mut sh) = setup("x", 400.0, 400.0);
+    let (h10, h40, h60, h20) = (
+        one_line_height(&p, &mut sh, 10.0),
+        one_line_height(&p, &mut sh, 40.0),
+        one_line_height(&p, &mut sh, 60.0),
+        one_line_height(&p, &mut sh, 20.0),
+    );
+    let put = |sh: &mut Shape, runs: Vec<Run>| {
+        sh.text.as_mut().unwrap().paragraphs = vec![Paragraph { runs, ..Default::default() }];
+    };
+
+    put(&mut sh, vec![sized_run("A1", 40.0), sized_break(40.0), sized_break(10.0), sized_run("A2", 40.0)]);
+    let a = lay(&p, &sh, 400.0, 400.0);
+    assert_eq!(a.lines.len(), 3, "{:?}", a.lines.iter().map(|l| l.top).collect::<Vec<_>>());
+    let empty_a = a.lines[2].top - a.lines[1].top;
+    assert!((empty_a - h10).abs() < 0.5, "a 10pt break should give a 10pt line ({h10}), got {empty_a}");
+    assert!((empty_a - h40).abs() > 1.0, "and not the 40pt first run's line ({h40})");
+
+    // Case C: a 60pt break closing the empty line of a 20pt paragraph pushes the third line
+    // down, the opposite direction from the first run's size -- so this cannot pass by the old
+    // behaviour under a different font.
+    put(&mut sh, vec![sized_run("C1", 20.0), sized_break(20.0), sized_break(60.0), sized_run("C2", 20.0)]);
+    let c = lay(&p, &sh, 400.0, 400.0);
+    let empty_c = c.lines[2].top - c.lines[1].top;
+    assert!((empty_c - h60).abs() < 0.5, "a 60pt break should give a 60pt line ({h60}), got {empty_c}");
+    assert!((empty_c - h20).abs() > 1.0, "and not the 20pt first run's line ({h20})");
+}
+
+#[test]
+fn an_empty_last_line_is_sized_by_the_paragraph_mark() {
+    // Case B: 40pt text and a trailing 40pt break, with the paragraph mark at 10pt. No break
+    // closes the empty last line, so it takes the mark's size.
+    let (p, mut sh) = setup("x", 400.0, 400.0);
+    let (h10, h40) = (one_line_height(&p, &mut sh, 10.0), one_line_height(&p, &mut sh, 40.0));
+    {
+        let t = sh.text.as_mut().unwrap();
+        let mut para = Paragraph { runs: vec![sized_run("B1", 40.0), sized_break(40.0)], ..Default::default() };
+        para.end_props.size = Some(10.0);
+        t.paragraphs = vec![para];
+    }
+    let l = lay(&p, &sh, 400.0, 400.0);
+    assert_eq!(l.lines.len(), 2, "the trailing break leaves an empty last line");
+    let h = l.lines[1].bottom - l.lines[1].top;
+    assert!((h - h10).abs() < 0.5, "a 10pt paragraph mark should give {h10}, got {h}");
+    assert!((h - h40).abs() > 1.0, "and not the 40pt first run's line ({h40})");
+}
+
+#[test]
+fn an_empty_paragraph_keeps_its_paragraph_mark_height() {
+    // Case D, the control: an empty *paragraph* already took `end_props` before this change,
+    // through `lead`, and must be unaffected by it.
+    let (p, mut sh) = setup("x", 400.0, 400.0);
+    let h10 = one_line_height(&p, &mut sh, 10.0);
+    {
+        let t = sh.text.as_mut().unwrap();
+        let mut empty = Paragraph::default();
+        empty.end_props.size = Some(10.0);
+        t.paragraphs = vec![
+            Paragraph { runs: vec![sized_run("D1", 40.0)], ..Default::default() },
+            empty,
+            Paragraph { runs: vec![sized_run("D2", 40.0)], ..Default::default() },
+        ];
+    }
+    let l = lay(&p, &sh, 400.0, 400.0);
+    assert_eq!(l.lines.len(), 3);
+    let h = l.lines[1].bottom - l.lines[1].top;
+    assert!((h - h10).abs() < 0.5, "a 10pt empty paragraph should give {h10}, got {h}");
+}

crates/ui-egui/src/huge_deck_tests.rs

@@ -37,3 +37,40 @@ fn the_outline_of_a_huge_deck_lays_out_only_what_is_in_view() {
     assert!(h.query_all_by_role(Role::TextInput).count() < 200);
     assert_eq!(h.state().session.doc().unwrap().selection.slide, 1500);
 }
+
+/// The thumbnail pane of an 800-slide deck renders only the thumbnails in view. When every row
+/// asked for one, a deck bigger than the 600-entry thumbnail cache evicted its own thumbnails before
+/// the pane was done, so the pane kept rendering and flashing white forever (#969).
+#[test]
+fn the_thumbnail_pane_of_a_huge_deck_renders_only_the_slides_in_view() {
+    let mut h = harness(800);
+    h.run_steps(60);
+    let settled = h.state().textures.thumb_count();
+    assert!(settled > 3 && settled < 60, "{settled} thumbnails rendered");
+    // The visible thumbnails are done: more frames render nothing new.
+    h.run_steps(10);
+    assert_eq!(h.state().textures.thumb_count(), settled);
+    // Scrolled far down, the slides now in view get their thumbnails, and only those.
+    h.hover_at(egui::pos2(100.0, 450.0));
+    h.event(egui::Event::MouseWheel {
+        unit: egui::MouseWheelUnit::Point,
+        delta: egui::vec2(0.0, -40_000.0),
+        modifiers: egui::Modifiers::NONE,
+        phase: egui::TouchPhase::Move,
+    });
+    h.run_steps(60);
+    let scrolled = h.state().textures.thumb_count();
+    assert!(scrolled > settled && scrolled < 2 * settled + 10, "{scrolled} thumbnails after scrolling (was {settled})");
+}
+
+/// The same in the Slide Sorter: only the cells in view render a thumbnail (#969).
+#[test]
+fn the_sorter_of_a_huge_deck_renders_only_the_slides_in_view() {
+    let mut h = harness(800);
+    h.state_mut().ui.view = crate::ViewMode::Sorter;
+    h.run_steps(60);
+    let settled = h.state().textures.thumb_count();
+    assert!(settled > 3 && settled < 80, "{settled} thumbnails rendered");
+    h.run_steps(10);
+    assert_eq!(h.state().textures.thumb_count(), settled);
+}

crates/ui-egui/src/sorter.rs

@@ -203,13 +203,17 @@ fn place_slides(app: &mut SlideApp, ui: &mut Ui, g: &Grid<'_>, budget: &mut u32,
                 let img = crate::textures::device_pixel_rect(Rect::from_min_size(cell.min + vec2(18.0, 8.0), vec2(g.tw, g.th)), ppp);
                 rects.push((i, cell));
                 let p = ui.painter();
-                match app.textures.thumb(ui.ctx(), g.doc, i, (img.width() * ppp).round() as u32, budget) {
+                // Only cells in view (plus a little margin) ask for a thumbnail, so a deck bigger
+                // than the thumbnail cache does not evict its own thumbnails forever (#969).
+                let near = ui.clip_rect().expand2(vec2(0.0, 2.0 * cell.height())).intersects(cell);
+                let tex = if near { app.textures.thumb(ui.ctx(), g.doc, i, (img.width() * ppp).round() as u32, budget) } else { None };
+                match tex {
                     Some(tex) => {
                         p.image(tex.id(), img, Rect::from_min_max(pos2(0.0, 0.0), pos2(1.0, 1.0)), Color32::WHITE);
                     }
                     None => {
                         p.rect_filled(img, CornerRadius::ZERO, Color32::WHITE);
-                        need_more = true;
+                        need_more |= near;
                     }
                 }
                 let id = g.doc.slides.get(i).map(|s| s.id);

crates/ui-egui/src/thumbs.rs

@@ -115,7 +115,11 @@ fn list(app: &mut SlideApp, ui: &mut Ui) {
             p.text(pos2(row.min.x + 14.0, img.min.y + 20.0), Align2::CENTER_TOP, "★", theme::font(10.0), t.text_faint);
         }
         let wpx = (img.width() * ppp).round() as u32;
-        match app.textures.thumb(ui.ctx(), &doc, i, wpx, &mut budget) {
+        // Only rows in view (plus a little margin) ask for a thumbnail: with every row asking, a
+        // deck bigger than the thumbnail cache evicts its own thumbnails and never settles (#969).
+        let near = ui.clip_rect().expand2(vec2(0.0, 2.0 * row.height())).intersects(row);
+        let tex = if near { app.textures.thumb(ui.ctx(), &doc, i, wpx, &mut budget) } else { None };
+        match tex {
             Some(tex) => {
                 p.image(
                     tex.id(),
@@ -126,7 +130,7 @@ fn list(app: &mut SlideApp, ui: &mut Ui) {
             }
             None => {
                 p.rect_filled(img, CornerRadius::ZERO, Color32::WHITE);
-                need_more = true;
+                need_more |= near;
             }
         }
         if selected {