PPTX: a slide that can't be read is reported, not dropped in silence (#203)

The importer skipped a slide whose part was missing or unreadable and only
logged it, so `info` showed one slide fewer with exit code 0 and a save wrote
the shorter deck over the original.

`deckcraft_pptx::import_checked` returns the parts it left out (`import` is
unchanged). The engine carries them as `Damage::slides` next to the damaged
media of a `.deckcraft` file: `file.open` and `file.openBytes` return
`lostSlides`, the app shows a message and opens a repaired copy (so Save asks
for a new name), and `deckcraft-cli` warns on stderr.

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


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# Changes to be committed:
#	modified:   Cargo.lock
#	modified:   ROADMAP.md
#	modified:   apps/deckcraft-cli/Cargo.toml
#	modified:   apps/deckcraft-cli/src/main.rs
#	new file:   apps/deckcraft-cli/tests/damaged.rs
#	modified:   crates/engine/src/cmd/file.rs
#	modified:   crates/engine/src/tests.rs
#	modified:   crates/pptx/src/lib.rs
#	modified:   crates/pptx/src/read/mod.rs
#	modified:   crates/pptx/tests/malformed.rs
#	modified:   docs/file-format-parity.md
#

Cargo.lock

@@ -941,6 +941,7 @@ dependencies = [
  "deckcraft-engine",
  "deckcraft-mcp",
  "serde_json",
+ "zip",
 ]
 
 [[package]]

ROADMAP.md

@@ -132,6 +132,7 @@ app's JSON control channel (`deckcraft --control PORT`).
 | Date | What landed |
 |---|---|
 | 2026-10-15 | CLI: .txt and .md export includes table cell text, which it used to skip silently (#814) |
+| 2026-10-15 | A `.pptx` slide that can't be read is reported, not dropped in silence: `lostSlides` from `file.open`, a message and a repaired copy in the app, a warning from `deckcraft-cli` (#203) |
 | 2026-10-15 | PDF export and rendering: `anchorCtr` centres the drawn text block — right-aligned text no longer ran past the box edge (#736) |
 | 2026-10-14 | connected MCP rejects unrelated, malformed, incomplete and oversized replies without replay; buffered unsolicited bytes force a fresh connection before sending (#718) |
 | 2026-10-14 | Empty bulleted and numbered paragraphs show gray markers while editing, including on first click and after Enter. Markers use the list style and stay out of slide shows and exports. |

apps/deckcraft-cli/Cargo.toml

@@ -17,3 +17,6 @@ path = "src/main.rs"
 deckcraft-engine = { workspace = true }
 deckcraft-mcp = { workspace = true }
 serde_json = { workspace = true }
+
+[dev-dependencies]
+zip = { workspace = true }

apps/deckcraft-cli/src/main.rs

@@ -117,11 +117,27 @@ fn open(s: &mut Session, input: Option<&str>, sample: bool) -> Result<(), String
         return deckcraft_engine::sample::open_sample(s).map_err(|e| e.to_string());
     }
     match input {
-        Some(p) => s.execute("file.open", &json!({"path": p})).map(|_| ()).map_err(|e| e.to_string()),
+        Some(p) => {
+            let opened = s.execute("file.open", &json!({"path": p})).map_err(|e| e.to_string())?;
+            warn_if_damaged(p, &opened);
+            Ok(())
+        }
         None => s.execute("file.new", &json!({})).map(|_| ()).map_err(|e| e.to_string()),
     }
 }
 
+/// Say on stderr what a file lost on opening, so a saved copy doesn't silently miss it (#203).
+fn warn_if_damaged(path: &str, opened: &serde_json::Value) {
+    let count = |key: &str| opened.get(key).and_then(|v| v.as_array()).map_or(0, |a| a.len());
+    let (slides, media) = (count("lostSlides"), count("damagedMedia"));
+    if slides > 0 {
+        eprintln!("deckcraft-cli: warning: {path}: {slides} slide{} couldn't be read and left out", if slides == 1 { "" } else { "s" });
+    }
+    if media > 0 {
+        eprintln!("deckcraft-cli: warning: {path}: {media} picture or media file{} couldn't be read", if media == 1 { "" } else { "s" });
+    }
+}
+
 /// Median and slowest of `runs` timings of `f`, in milliseconds.
 fn time_ms(runs: usize, mut f: impl FnMut() -> Result<(), String>) -> Result<(f64, f64), String> {
     let mut ms = Vec::with_capacity(runs);

apps/deckcraft-cli/tests/damaged.rs

@@ -0,0 +1,53 @@
+//! Opening a `.pptx` that lost slides says so on stderr instead of saving a shorter deck in silence (#203).
+
+use std::io::{Cursor, Read, Write};
+use std::path::PathBuf;
+use std::process::{Command, Output};
+
+fn cli(args: &[&str]) -> Output {
+    Command::new(env!("CARGO_BIN_EXE_deckcraft-cli")).args(args).output().unwrap()
+}
+
+fn temp_dir(name: &str) -> PathBuf {
+    let dir = std::env::temp_dir().join(format!("deckcraft-cli-{name}-{}", std::process::id()));
+    let _ = std::fs::remove_dir_all(&dir);
+    std::fs::create_dir_all(&dir).unwrap();
+    dir
+}
+
+/// `deck` with `ppt/slides/slide2.xml` cut off.
+fn without_slide2(deck: &[u8]) -> Vec<u8> {
+    let mut zin = zip::ZipArchive::new(Cursor::new(deck)).unwrap();
+    let mut out = zip::ZipWriter::new(Cursor::new(Vec::new()));
+    let options = zip::write::SimpleFileOptions::default();
+    for i in 0..zin.len() {
+        let mut f = zin.by_index(i).unwrap();
+        let mut data = vec![];
+        f.read_to_end(&mut data).unwrap();
+        if f.name() == "ppt/slides/slide2.xml" {
+            data = b"<p:sld".to_vec();
+        }
+        out.start_file(f.name(), options).unwrap();
+        out.write_all(&data).unwrap();
+    }
+    out.finish().unwrap().into_inner()
+}
+
+#[test]
+fn a_pptx_with_an_unreadable_slide_is_reported_on_stderr() {
+    let dir = temp_dir("lost-slide");
+    let good = dir.join("good.pptx");
+    let made = cli(&["run", "--sample", "--save", good.to_str().unwrap()]);
+    assert!(made.status.success(), "{}", String::from_utf8_lossy(&made.stderr));
+    let broken = dir.join("broken.pptx");
+    std::fs::write(&broken, without_slide2(&std::fs::read(&good).unwrap())).unwrap();
+
+    let ok = cli(&["info", good.to_str().unwrap()]);
+    assert!(ok.status.success() && !String::from_utf8_lossy(&ok.stderr).contains("warning"), "{}", String::from_utf8_lossy(&ok.stderr));
+
+    let bad = cli(&["info", broken.to_str().unwrap()]);
+    assert!(bad.status.success(), "{}", String::from_utf8_lossy(&bad.stderr));
+    let err = String::from_utf8_lossy(&bad.stderr);
+    assert!(err.contains("warning") && err.contains("1 slide couldn't be read and left out"), "{err}");
+    let _ = std::fs::remove_dir_all(&dir);
+}

crates/engine/src/cmd/file.rs

@@ -128,19 +128,35 @@ pub fn open_presentation(name: &str, bytes: &[u8]) -> Result<Presentation> {
     open_checked(name, bytes).map(|(p, _)| p)
 }
 
-/// [`open_presentation`], plus the embedded media a `.deckcraft` file had lost or damaged.
+/// What a file lost on opening.
-pub fn open_checked(name: &str, bytes: &[u8]) -> Result<(Presentation, Vec<String>)> {
+#[derive(Debug, Default, Clone)]
-    if deckcraft_format::sniff(bytes) {
+pub struct Damage {
-        return deckcraft_format::load_checked(bytes).map_err(|e| EngineError::Other(e.to_string()));
+    /// Pictures and media a `.deckcraft` file had lost or damaged.
-    }
+    pub media: Vec<String>,
-    open_other(name, bytes).map(|p| (p, vec![]))
+    /// Slides a `.pptx` lists but that couldn't be read, so they are not in the presentation.
+    pub slides: Vec<String>,
 }
 
-fn open_other(name: &str, bytes: &[u8]) -> Result<Presentation> {
+impl Damage {
+    pub fn is_empty(&self) -> bool {
+        self.media.is_empty() && self.slides.is_empty()
+    }
+}
+
+/// [`open_presentation`], plus what the file had lost or damaged.
+pub fn open_checked(name: &str, bytes: &[u8]) -> Result<(Presentation, Damage)> {
+    if deckcraft_format::sniff(bytes) {
+        let (p, media) = deckcraft_format::load_checked(bytes).map_err(|e| EngineError::Other(e.to_string()))?;
+        return Ok((p, Damage { media, slides: vec![] }));
+    }
+    open_other(name, bytes).map(|(p, slides)| (p, Damage { media: vec![], slides }))
+}
+
+fn open_other(name: &str, bytes: &[u8]) -> Result<(Presentation, Vec<String>)> {
     if deckcraft_pptx::sniff(bytes) {
-        let mut p = deckcraft_pptx::import(bytes).map_err(|e| EngineError::Other(e.to_string()))?;
+        let (mut p, lost_slides) = deckcraft_pptx::import_checked(bytes).map_err(|e| EngineError::Other(e.to_string()))?;
         deckcraft_format::repair(&mut p);
-        return Ok(p);
+        return Ok((p, lost_slides));
     }
     if deckcraft_pptx::is_encrypted(bytes) {
         return Err(EngineError::Other(format!("{name} is password-protected. DeckCraft can't open password-protected presentations yet.")));
@@ -157,7 +173,7 @@ fn open_other(name: &str, bytes: &[u8]) -> Result<Presentation> {
         if p.slides.is_empty() {
             p = defaults::new_presentation(None);
         }
-        return Ok(p);
+        return Ok((p, vec![]));
     }
     Err(EngineError::Other(format!("{name}: not a presentation DeckCraft can read")))
 }
@@ -180,8 +196,8 @@ pub struct LoadedFile {
     pub doc: Presentation,
     /// A native or PPTX file (saving goes back to it); an outline import has no file to save to.
     pub native: bool,
-    /// Pictures and media a `.deckcraft` file had lost or damaged.
+    /// What the file had lost or damaged.
-    pub damaged: Vec<String>,
+    pub damaged: Damage,
 }
 
 /// Read and parse the presentation at `path`.
@@ -202,7 +218,10 @@ fn adopt_loaded(s: &mut Session, f: LoadedFile) -> Result<Value> {
     let i = add_opened(s, &path, keep_path.then(|| path.clone()), doc);
     report_damage(s, &damaged)?;
     let st = s.doc()?;
-    Ok(json!({"document": i, "slides": st.doc.slides.len(), "missingFonts": st.missing_fonts, "damagedMedia": damaged}))
+    Ok(json!({
+        "document": i, "slides": st.doc.slides.len(), "missingFonts": st.missing_fonts,
+        "damagedMedia": damaged.media, "lostSlides": damaged.slides,
+    }))
 }
 
 #[cfg(not(target_arch = "wasm32"))]
@@ -236,23 +255,35 @@ fn open_bytes(s: &mut Session, p: &Value) -> Result<Value> {
     let (doc, damaged) = open_checked(name, &data)?;
     let i = add_opened(s, name, None, doc);
     report_damage(s, &damaged)?;
-    Ok(json!({"document": i, "missingFonts": s.doc()?.missing_fonts, "damagedMedia": damaged}))
+    Ok(json!({"document": i, "missingFonts": s.doc()?.missing_fonts, "damagedMedia": damaged.media, "lostSlides": damaged.slides}))
 }
 
-/// Tell the user which pictures and media a damaged file lost, and mark the copy repaired.
+/// Tell the user which pictures, media and slides a damaged file lost, and mark the copy repaired.
-fn report_damage(s: &mut Session, damaged: &[String]) -> Result<()> {
+fn report_damage(s: &mut Session, damaged: &Damage) -> Result<()> {
     if damaged.is_empty() {
         return Ok(());
     }
     let st = s.doc_mut()?;
     st.title = format!("{} (Repaired)", st.title);
-    let n = damaged.len();
+    let mut text = String::new();
-    let text = format!(
+    let n = damaged.media.len();
-        "{n} picture{} or media file{} in this presentation couldn't be read and {} empty. It was opened as a repaired copy; save it under a new name to keep the original file.",
+    if n > 0 {
-        if n == 1 { "" } else { "s" },
+        text = format!(
-        if n == 1 { "" } else { "s" },
+            "{n} picture{} or media file{} in this presentation couldn't be read and {} empty. ",
-        if n == 1 { "is" } else { "are" },
+            if n == 1 { "" } else { "s" },
-    );
+            if n == 1 { "" } else { "s" },
+            if n == 1 { "is" } else { "are" },
+        );
+    }
+    let n = damaged.slides.len();
+    if n > 0 {
+        text.push_str(&format!(
+            "{n} slide{} in this file couldn't be read and {} left out. ",
+            if n == 1 { "" } else { "s" },
+            if n == 1 { "was" } else { "were" },
+        ));
+    }
+    text.push_str("It was opened as a repaired copy; save it under a new name to keep the original file.");
     s.ui_requests.push(crate::UiRequest::Message { text });
     Ok(())
 }

crates/engine/src/tests.rs

@@ -3517,7 +3517,8 @@ fn background_loads_are_adopted_through_a_command() {
     replay.execute(&id, &params).unwrap();
     assert_eq!(replay.doc().unwrap().doc.slides.len(), 2);
     // A token staged for another path is not taken for this one.
-    let other = s.stage_loaded(cmd::file::LoadedFile { path: "/elsewhere.pptx".into(), doc: Default::default(), native: true, damaged: vec![] });
+    let other =
+        s.stage_loaded(cmd::file::LoadedFile { path: "/elsewhere.pptx".into(), doc: Default::default(), native: true, damaged: Default::default() });
     s.execute("file.adopt", &json!({"path": path, "token": other})).unwrap();
     assert_eq!(s.doc().unwrap().doc.slides.len(), 2);
     assert!(s.execute("file.adopt", &json!({})).is_err());
@@ -3592,3 +3593,38 @@ fn table_insert_below_or_right_of_a_huge_index_appends_at_the_end() {
     assert_eq!(t.n_cols(), 3);
     assert_eq!(t.cell(0, 1).unwrap().text.text(), "b", "the original columns keep their place");
 }
+
+#[test]
+fn opening_a_pptx_with_an_unreadable_slide_says_so() {
+    use std::io::{Cursor, Read, Write};
+    let mut s = session();
+    s.execute("slide.new", &json!({"layout": "blank"})).unwrap();
+    assert_eq!(s.doc().unwrap().doc.slides.len(), 2);
+    let good = deckcraft_pptx::export(s.doc().unwrap().doc.as_ref()).unwrap();
+    let mut zin = zip::ZipArchive::new(Cursor::new(good.clone())).unwrap();
+    let mut out = zip::ZipWriter::new(Cursor::new(Vec::new()));
+    let o = zip::write::SimpleFileOptions::default();
+    for i in 0..zin.len() {
+        let mut f = zin.by_index(i).unwrap();
+        let mut d = vec![];
+        f.read_to_end(&mut d).unwrap();
+        if f.name() == "ppt/slides/slide2.xml" {
+            d = b"<p:sld".to_vec();
+        }
+        out.start_file(f.name(), o).unwrap();
+        out.write_all(&d).unwrap();
+    }
+    let broken = out.finish().unwrap().into_inner();
+
+    let mut t = session();
+    let r = t.execute("file.openBytes", &json!({"name": "Broken.pptx", "data": cmd::base64_encode(&broken)})).unwrap();
+    assert_eq!(r["lostSlides"], json!(["ppt/slides/slide2.xml"]), "{r}");
+    assert_eq!(t.doc().unwrap().doc.slides.len(), 1);
+    assert!(t.doc().unwrap().title.ends_with("(Repaired)"), "{}", t.doc().unwrap().title);
+    assert!(t.ui_requests.iter().any(|u| matches!(u, crate::UiRequest::Message { text } if text.contains("1 slide in this file couldn't be read"))));
+    // A good file reports nothing.
+    let mut u = session();
+    let r = u.execute("file.openBytes", &json!({"name": "Fine.pptx", "data": cmd::base64_encode(&good)})).unwrap();
+    assert_eq!(r["lostSlides"], json!([]), "{r}");
+    assert!(u.ui_requests.is_empty());
+}

crates/pptx/src/lib.rs

@@ -63,6 +63,12 @@ pub fn import(bytes: &[u8]) -> Result<Presentation, PptxError> {
     read::import(bytes)
 }
 
+/// [`import`], plus the part names of slides the file lists but that couldn't be read and were
+/// left out.
+pub fn import_checked(bytes: &[u8]) -> Result<(Presentation, Vec<String>), PptxError> {
+    read::import_checked(bytes)
+}
+
 /// Read the theme of a `.thmx` file, or of a `.pptx` / `.potx`'s first master, with its media.
 pub fn import_theme(bytes: &[u8]) -> Result<(deckcraft_model::theme::Theme, Vec<deckcraft_model::MediaItem>), PptxError> {
     read::import_theme(bytes)

crates/pptx/src/read/mod.rs

@@ -387,6 +387,13 @@ pub fn import_theme(bytes: &[u8]) -> Result<(deckcraft_model::theme::Theme, Vec<
 }
 
 pub fn import(bytes: &[u8]) -> Result<Presentation, PptxError> {
+    import_checked(bytes).map(|(p, _)| p)
+}
+
+/// [`import`], plus the parts of the slide list the file names but that couldn't be read (a
+/// missing or truncated slide): those slides are left out, so a caller can say so (#203).
+pub fn import_checked(bytes: &[u8]) -> Result<(Presentation, Vec<String>), PptxError> {
+    let mut lost_slides: Vec<String> = vec![];
     let pkg = Package::open(bytes)?;
     let root_rels = pkg.rels("");
     let pres_path = root_rels.first_of("officeDocument").map(|r| r.target.clone()).unwrap_or_else(|| "ppt/presentation.xml".into());
@@ -447,6 +454,7 @@ pub fn import(bytes: &[u8]) -> Result<Presentation, PptxError> {
     for (file_id, path) in &slide_entries {
         if !docs.contains_key(&opc::norm(path)) {
             log::warn!("pptx: slide {path} is missing or unreadable; skipped");
+            lost_slides.push(path.clone());
             continue;
         }
         let id = SlideId(imp.alloc());
@@ -677,7 +685,7 @@ pub fn import(bytes: &[u8]) -> Result<Presentation, PptxError> {
     p.media = std::mem::take(&mut imp.media);
     p.next_id = imp.next;
     p.fix_next_id();
-    Ok(p)
+    Ok((p, lost_slides))
 }
 
 /// Embedded font faces in one file. Past this, further typefaces are dropped.

crates/pptx/tests/malformed.rs

@@ -264,3 +264,26 @@ fn export_of_odd_models_is_valid() {
     let q = deckcraft_pptx::import(&deckcraft_pptx::export(&empty).expect("export")).expect("import");
     assert!(!q.masters.is_empty());
 }
+
+/// A slide the file lists but that can't be read is left out, and `import_checked` names it
+/// where `import` would have said nothing (#203).
+#[test]
+fn unreadable_slide_is_reported() {
+    let mut p = defaults::new_presentation(None);
+    let mut second = p.slides.first().expect("a slide").as_ref().clone();
+    second.id = deckcraft_model::SlideId(second.id.0 + 1000);
+    p.slides.push(std::sync::Arc::new(second));
+    let bytes = deckcraft_pptx::export(&p).expect("export");
+
+    let (q, lost) = deckcraft_pptx::import_checked(&bytes).expect("import");
+    assert_eq!((q.slides.len(), lost.len()), (2, 0), "{lost:?}");
+
+    let mut es = entries(&bytes);
+    let slide2 = es.iter_mut().find(|(n, _)| n == "ppt/slides/slide2.xml").expect("slide2");
+    slide2.1 = b"<p:sld".to_vec();
+    let broken = rezip(&es);
+    let (q, lost) = deckcraft_pptx::import_checked(&broken).expect("import");
+    assert_eq!(q.slides.len(), 1);
+    assert_eq!(lost, vec!["ppt/slides/slide2.xml".to_string()]);
+    assert_eq!(deckcraft_pptx::import(&broken).expect("import").slides.len(), 1);
+}

docs/file-format-parity.md

@@ -1,6 +1,6 @@
 # File-format parity with PowerPoint
 
-> **Last reviewed:** 2026-10-14 · **Last updated:** 2026-10-14 · **Change:** major (community PR wave 2026-10-14: seven owned PPTX corpus files, embedded fonts, EMF/WMF clip regions, threaded comments (#70), chart trendlines and workbooks (#335), SmartArt written as a diagram, tags and custom XML kept, picture export DPI; duplicated rows and headers folded; previous: trivial, lines in scaled groups, #233) · **Target:** Microsoft PowerPoint for Mac 16.113 (Microsoft 365)
+> **Last reviewed:** 2026-10-14 · **Last updated:** 2026-10-15 · **Change:** major (community PR wave 2026-10-14: seven owned PPTX corpus files, embedded fonts, EMF/WMF clip regions, threaded comments (#70), chart trendlines and workbooks (#335), SmartArt written as a diagram, tags and custom XML kept, picture export DPI; duplicated rows and headers folded; previous: trivial, lines in scaled groups, #233) · **Target:** Microsoft PowerPoint for Mac 16.113 (Microsoft 365)
 
 Every format PowerPoint reads or writes, DeckCraft's support, fidelity and how it is tested.
 Gaps are itemized in [gaps.md](gaps.md#file-formats). Dimension score: **~58% ready**
@@ -103,6 +103,7 @@ the round trip even though DeckCraft doesn't model it.
 
 | Date | Change | Summary |
 |---|---|---|
+| 2026-10-15 | minor | A `.pptx` slide that can't be read is reported instead of dropped in silence: `file.open` and `file.openBytes` return `lostSlides`, the app shows a message and opens a repaired copy (Save asks for a new name), and `deckcraft-cli` warns on stderr (#203) |
 | 2026-10-14 | minor | Community PR wave folded: one row each for `.pptx` (seven owned corpus files), outline, 3-D models, embedded fonts, text, effects, 3-D (extrusion sides draw now), SmartArt (written as a diagram) and VBA (tags and custom XML are kept) |
 | 2026-10-12 | minor | SmartArt import lays each shape's text out on its `dsp:txXfrm` text rectangle instead of the shape box |
 | 2026-10-13 | minor | EMF/WMF rectangle clip regions limit later drawing; EMF+ records remain |