Merge pull request #5816 from KenM76/feat/unreadable-object-report

feat(cos): list the objects that could not be read in doc_info

crates/automation/src/json.rs

@@ -375,6 +375,9 @@ pub(crate) fn info(d: &Document) -> Value {
         })).collect::<Vec<_>>(),
         "warnings": i.warnings,
         "repairs": d.repair_log(),
+        // Objects that could not be read (each reads as null): nothing was repaired, what they held is
+        // lost. Last, so it includes what reading the fields above failed on.
+        "unreadable_objects": d.unreadable_objects(),
     })
 }
 

crates/automation/src/tools.rs

@@ -164,7 +164,7 @@ pub fn tools() -> Vec<ToolDef> {
             .cmd("file.open")
             .with(schema(json!({ "path": { "type": "string" }, "password": { "type": "string", "description": "User or owner password for encrypted files." } }), &["path"])),
         t("doc_list", "List open documents", "List the open documents with their ids, page counts and unsaved state.").ro().with(schema(json!({}), &[])),
-        t("doc_info", "Inspect a document", "Metadata, page sizes and labels, bookmarks, annotations, form fields, links, layers, page transitions and display times, the destination it opens at, attachments, fonts, security and repair notes.")
+        t("doc_info", "Inspect a document", "Metadata, page sizes and labels, bookmarks, annotations, form fields, links, layers, page transitions and display times, the destination it opens at, attachments, fonts, security, repair notes and the objects that could not be read.")
             .ro()
             .cmd("file.properties")
             .with(schema(json!({ "doc": doc() }), &["doc"])),

crates/automation/tests/it/main.rs

@@ -17,3 +17,4 @@ mod optimize_content_boundaries;
 mod redact_after_stray_q_form;
 mod redact_text_after_q;
 mod render_warnings;
+mod unreadable_objects;

crates/automation/tests/it/unreadable_objects.rs

@@ -0,0 +1,64 @@
+//! `doc_info` lists the objects of a file that could not be read: each reads as null, so the file
+//! opens, but what it held is lost and nothing was repaired.
+
+use pdfcraft_automation::{Automation, Content};
+use serde_json::{Value, json};
+
+/// A one-page PDF whose document information dictionary (object 4) is `info`.
+fn with_info(info: &str) -> Vec<u8> {
+    let bodies = [
+        "<< /Type /Catalog /Pages 2 0 R >>",
+        "<< /Type /Pages /Kids [3 0 R] /Count 1 >>",
+        "<< /Type /Page /Parent 2 0 R /MediaBox [0 0 200 200] >>",
+        info,
+    ];
+    let mut out = b"%PDF-1.7\n".to_vec();
+    let mut offsets = Vec::new();
+    for (i, body) in bodies.iter().enumerate() {
+        offsets.push(out.len());
+        out.extend_from_slice(format!("{} 0 obj\n{body}\nendobj\n", i + 1).as_bytes());
+    }
+    let xref = out.len();
+    out.extend_from_slice(format!("xref\n0 {}\n0000000000 65535 f \n", bodies.len() + 1).as_bytes());
+    for o in offsets {
+        out.extend_from_slice(format!("{o:010} 00000 n \n").as_bytes());
+    }
+    out.extend_from_slice(format!("trailer\n<< /Size {} /Root 1 0 R /Info 4 0 R >>\nstartxref\n{xref}\n%%EOF\n", bodies.len() + 1).as_bytes());
+    out
+}
+
+fn info_of(a: &mut Automation, path: &str) -> Value {
+    let doc = match a.call("doc_open", &json!({ "path": path })).unwrap().remove(0) {
+        Content::Json(v) => v["doc"].as_u64().unwrap(),
+        other => panic!("expected JSON: {other:?}"),
+    };
+    match a.call("doc_info", &json!({ "doc": doc })).unwrap().remove(0) {
+        Content::Json(v) => v,
+        other => panic!("expected JSON: {other:?}"),
+    }
+}
+
+/// An unparseable `/Info` is listed with its number and why, the rest of the file reads, and
+/// nothing is reported as repaired.
+#[test]
+fn doc_info_lists_an_object_that_could_not_be_read() {
+    let dir = std::env::temp_dir().join(format!("pdfcraft-unreadable-objects-{}", std::process::id()));
+    let _ = std::fs::remove_dir_all(&dir);
+    std::fs::create_dir_all(&dir).unwrap();
+    std::fs::write(dir.join("broken.pdf"), with_info("<< /Title (Report) /Author ) >>")).unwrap();
+    std::fs::write(dir.join("sound.pdf"), with_info("<< /Title (Report) >>")).unwrap();
+    let mut a = Automation::new().with_root(&dir).unwrap();
+
+    let info = info_of(&mut a, "broken.pdf");
+    let lines = info["unreadable_objects"].as_array().unwrap();
+    assert_eq!(lines.len(), 1, "{info}");
+    let line = lines[0].as_str().unwrap();
+    assert!(line.starts_with("object 4 0 could not be read: syntax error"), "{line}");
+    assert_eq!(info["repairs"], json!([]), "nothing was repaired");
+    assert_eq!(info["pages"].as_array().unwrap().len(), 1, "the rest of the file reads");
+
+    let info = info_of(&mut a, "sound.pdf");
+    assert_eq!(info["unreadable_objects"], json!([]), "{info}");
+    assert_eq!(info["title"], "Report");
+    let _ = std::fs::remove_dir_all(dir);
+}

crates/cos/src/document.rs

@@ -25,7 +25,7 @@ pub(crate) use reader::find;
 #[cfg(test)]
 use reader::rfind;
 pub(crate) use state::ObjectReader;
-use state::{ObjStm, Slot};
+use state::{ObjStm, Slot, Unreadable};
 pub use state::{ReadState, SourceIdentity};
 #[cfg(test)]
 use state::{SECTION_READS, held_bytes, objstm_member};
@@ -53,6 +53,9 @@ pub struct Document {
     /// decodes the stream again (`Document::load`).
     cache: Arc<Mutex<state::ObjectCache>>,
     objstms: Arc<Mutex<HashMap<u32, Arc<ObjStm>>>>,
+    /// See [`Self::unreadable_objects`]. Shared by clones, like the caches: it describes the
+    /// source, and is reset wherever they are.
+    unreadable: Arc<Mutex<Unreadable>>,
     /// What `/JBIG2Globals` streams of the file decode to, by object number: the images of a scan
     /// share them, and each would otherwise decode them again (see `Document::jbig2_globals`).
     jbig2_globals: Arc<Mutex<HashMap<u32, Arc<Vec<u8>>>>>,

crates/cos/src/document/objects.rs

@@ -90,6 +90,39 @@ impl Document {
         &self.repair_log
     }
 
+    /// Objects of the file that could not be read, lowest number first, as lines such as
+    /// "object 11 0 could not be read: syntax error at byte 512: ...". [`Self::get`] reads each
+    /// as null (ISO 32000-2 §7.3.10), so a document with one opens, but what it held is lost:
+    /// unlike [`Self::repair_log`], nothing was repaired. Lists the objects read so far, by this
+    /// document, its clones or a scan of it, that have not since been edited; past 100, a last
+    /// line says there were more. Opening again, authenticating or rebuilding the index starts
+    /// the list afresh, as it does the object cache.
+    pub fn unreadable_objects(&self) -> Vec<String> {
+        let Ok(unreadable) = self.unreadable.lock() else { return Vec::new() };
+        unreadable.lines(|num| self.overlay.contains_key(&num))
+    }
+
+    /// Record `num` as unreadable. `reason` is built only for an object not yet listed, so a file
+    /// whose broken object is asked for again and again pays for it once.
+    fn note_unreadable(&self, num: u32, reason: impl FnOnce() -> String) {
+        // A poisoned lock only means the object goes unlisted; the read itself still fails.
+        let Ok(mut unreadable) = self.unreadable.lock() else { return };
+        let hidden = |n: u32| self.overlay.contains_key(&n);
+        if unreadable.wants(num, hidden) {
+            unreadable.note(num, self.generation(num), &reason(), hidden);
+        }
+    }
+
+    /// Why an object listed at `offset` could not be read: what parsing it there, without resolving
+    /// an indirect `/Length`, found. A best account, not the only one: the reader also tried
+    /// elsewhere.
+    fn why_unreadable(&self, offset: usize) -> String {
+        match parse_indirect_shared(&self.data, offset, &|_| None, &self.endstreams) {
+            Err(e) => e.to_string(),
+            Ok(_) => "no readable copy was found at its cross-reference offset or elsewhere in the file".into(),
+        }
+    }
+
     /// Add a line to [`Self::repair_log`]: a leniency applied while reading that the user should
     /// know about (fidelity: never silent).
     pub fn note_repair(&mut self, line: String) {
@@ -516,6 +549,11 @@ impl Document {
         let _scope = crate::security::FollowScope::enter();
         let edits_read = overlay_reads();
         let loaded = self.load(num, 0).map(Arc::new);
+        if let Err(e) = &loaded
+            && !matches!(e, CosError::Poisoned)
+        {
+            self.note_unreadable(num, || e.to_string());
+        }
         // A failure is kept like an object, or every read of a damaged object loads it again. A
         // poisoned lock says nothing about the object. Clones share the cache, so a load that read
         // this document's edits (an edited object stream or `/Length`) is not kept.
@@ -663,7 +701,10 @@ impl Document {
                     .or_else(|| if self.header_offset == 0 { None } else { at(off.saturating_add(self.header_offset)) })
                     .or_else(|| self.located.get(&num).and_then(|(o, _)| usize::try_from(*o).ok()).and_then(at))
                     .or_else(|| self.scan_for(num).map(|(id, o)| self.decrypted(id, o)))
-                    .ok_or(CosError::MissingObject(num))
+                    .ok_or_else(|| {
+                        self.note_unreadable(num, || self.why_unreadable(off));
+                        CosError::MissingObject(num)
+                    })
             }
             Some(XrefEntry::InStream { stream, index }) => {
                 let stm = self.objstm(stream)?;

crates/cos/src/document/open.rs

@@ -23,6 +23,7 @@ impl Document {
             repair_log: Arc::new(Vec::new()),
             cache: Arc::default(),
             objstms: Arc::default(),
+            unreadable: Arc::default(),
             jbig2_globals: Arc::default(),
             stream_limit: crate::object::MAX_DECODED,
             overlay: BTreeMap::new(),
@@ -110,6 +111,7 @@ impl Document {
             repair_log: Arc::new(Vec::new()),
             cache: Arc::default(),
             objstms: Arc::default(),
+            unreadable: Arc::default(),
             jbig2_globals: Arc::default(),
             stream_limit: stream_limit.min(crate::object::MAX_DECODED),
             overlay: BTreeMap::new(),
@@ -216,6 +218,7 @@ impl Document {
         // Objects read while locating the catalog were read before decryption was possible.
         self.cache = Arc::default();
         self.objstms = Arc::default();
+        self.unreadable = Arc::default();
         Ok(())
     }
 

crates/cos/src/document/reader.rs

@@ -1,5 +1,6 @@
 #[cfg(test)]
 use super::state::SECTION_READS;
+use super::state::Unreadable;
 use super::xref::{
     MAX_COMPACT_XREF_BYTES, MAX_COMPACT_XREF_ROWS, Revision, XrefEntry, XrefIndex, XrefRange, XrefRevisionSection, XrefSection, XrefSectionData,
 };
@@ -648,6 +649,7 @@ impl Document {
         }
         self.entries = Arc::new(XrefIndex::Materialized(Arc::new(entries.clone()), Arc::default()));
         self.cache.lock().map_err(|_| CosError::Poisoned)?.clear();
+        *self.unreadable.lock().map_err(|_| CosError::Poisoned)? = Unreadable::default();
         // Objects inside object streams.
         for num in objstms {
             if let Ok(o) = self.try_get(num)
@@ -664,6 +666,8 @@ impl Document {
         }
         let object_count = entries.len();
         self.entries = Arc::new(XrefIndex::Materialized(Arc::new(entries), Arc::default()));
+        // Failures from the scan stand: the members added change no scanned entry, and a
+        // `/Length` found only now cannot make a stream unreadable.
         self.cache.lock().map_err(|_| CosError::Poisoned)?.clear();
         // Trailer: the last `trailer` dictionary or cross-reference stream dictionary with a
         // usable /Root (last in the file, whichever kind), else the catalog itself. One whose

crates/cos/src/document/state.rs

@@ -81,6 +81,60 @@ pub(super) fn objstm_member(num: i64, offset: i64, first: Option<usize>, len: us
     (start < len).then_some((num, start))
 }
 
+/// Objects the reader could not read, each with the reason (see `Document::unreadable_objects`).
+/// Bounded: a document records past [`Unreadable::MAX`] of the objects it shows only the fact that
+/// there were more. Entries a clone has edited are hidden from it and do not count, so the whole
+/// list holds at most `MAX` plus the objects edited in clones.
+#[derive(Debug, Default)]
+pub(super) struct Unreadable {
+    pub(super) objects: BTreeMap<u32, (u16, String)>,
+    pub(super) more: bool,
+}
+
+impl Unreadable {
+    pub(super) const MAX: usize = 100;
+    /// Characters of a reason kept: a parser's message can quote the bytes it stopped at.
+    const REASON: usize = 160;
+
+    /// Whether `num` is to be recorded: not listed yet and there is room among the entries the
+    /// asking document still shows (`hidden` are the ones it has edited, as in [`Self::lines`]),
+    /// so a clone's edits never use up its own allowance. A full list notes that there were more,
+    /// so a caller asks this before building the reason.
+    pub(super) fn wants(&mut self, num: u32, hidden: impl Fn(u32) -> bool) -> bool {
+        if self.objects.contains_key(&num) {
+            return false;
+        }
+        if self.objects.keys().filter(|n| !hidden(**n)).count() >= Self::MAX {
+            self.more = true;
+            return false;
+        }
+        true
+    }
+
+    /// Record `num` once; the first reason given is kept.
+    pub(super) fn note(&mut self, num: u32, generation: u16, reason: &str, hidden: impl Fn(u32) -> bool) {
+        if self.wants(num, hidden) {
+            self.objects.insert(num, (generation, reason.chars().take(Self::REASON).collect()));
+        }
+    }
+
+    /// One line per recorded object not `hidden`, then one saying there were more, if there were.
+    pub(super) fn lines(&self, hidden: impl Fn(u32) -> bool) -> Vec<String> {
+        // Clones share the list and each hides its own edits, so the list may hold more than
+        // `MAX` entries in all; each document still shows at most `MAX`.
+        let mut shown = self.objects.iter().filter(|(num, _)| !hidden(**num));
+        let mut lines: Vec<String> = shown
+            .by_ref()
+            .take(Self::MAX)
+            .map(|(num, (generation, reason))| format!("object {num} {generation} could not be read: {reason}"))
+            .collect();
+        if self.more || shown.next().is_some() {
+            lines.push(format!("more objects could not be read; only the first {} are listed", Self::MAX));
+        }
+        lines
+    }
+}
+
 /// Where an overlay slot came from.
 #[derive(Clone, Debug, PartialEq)]
 pub(super) enum Slot {

crates/cos/src/document/tests.rs

@@ -749,6 +749,9 @@ fn an_unreadable_object_is_searched_for_once() {
     let mut edited = doc.clone();
     assert_eq!(edited.try_get(3), first);
     assert_eq!(FILE_SCANS.with(std::cell::Cell::get), 1, "searches for an object that isn't there");
+    let report = doc.unreadable_objects();
+    assert_eq!(report.len(), 1, "cached failures must stay listed exactly once: {report:?}");
+    assert_eq!(edited.unreadable_objects(), report, "clones retain the cached failure diagnostic");
     edited.set(ObjRef::new(3, 0), Object::Int(7));
     assert_eq!(edited.try_get(3).as_deref(), Ok(&Object::Int(7)));
     assert_eq!(doc.try_get(3), first, "the edit is the clone's alone");
@@ -2015,6 +2018,105 @@ fn a_stream_whose_length_is_itself_and_never_ends_loads_quickly() {
     rx.recv_timeout(std::time::Duration::from_secs(20)).expect("loading must not retry exponentially");
 }
 
+/// A file whose object 3 (its `/Info`) can't be parsed: the rest reads.
+fn with_unreadable_info() -> Vec<u8> {
+    build(
+        &["<< /Type /Catalog /Pages 2 0 R >>", "<< /Type /Pages /Kids [] /Count 0 >>", "<< /Title (Report) /Author ) >>"],
+        "/Root 1 0 R /Info 3 0 R",
+    )
+}
+
+/// An object that can't be parsed reads as null and is listed once, by number and generation,
+/// with why. Clones and scans share the list, an edit takes the object off it (in that document
+/// only), and a sound file lists nothing.
+#[test]
+fn unreadable_objects_are_listed_with_the_reason() {
+    let doc = Document::open(Arc::new(with_unreadable_info())).unwrap();
+    assert!(doc.unreadable_objects().is_empty(), "nothing has read object 3 yet");
+    assert_eq!(*doc.get(ObjRef::new(3, 0)), Object::Null);
+    assert!(doc.try_get(3).is_err());
+    let lines = doc.unreadable_objects();
+    assert_eq!(lines.len(), 1, "read twice, listed once: {lines:?}");
+    assert!(lines[0].starts_with("object 3 0 could not be read: syntax error"), "{lines:?}");
+    let scanned = doc.clone();
+    assert_eq!(scanned.scan_objects_checked().filter(|(_, o)| o.is_err()).count(), 1);
+    assert_eq!(doc.unreadable_objects(), lines, "the scan found the same object");
+    let unread = Document::open(Arc::new(with_unreadable_info())).unwrap();
+    let scanned = unread.clone();
+    assert_eq!(scanned.scan_objects_checked().filter(|(_, o)| o.is_err()).count(), 1);
+    assert_eq!(unread.unreadable_objects(), lines, "a clone's scan reaches the original");
+    let mut edited = doc.clone();
+    edited.set(ObjRef::new(3, 0), Object::Dict(Dict::new()));
+    assert!(edited.unreadable_objects().is_empty(), "the edit replaced it");
+    assert_eq!(doc.unreadable_objects(), lines);
+    let sound =
+        build(&["<< /Type /Catalog /Pages 2 0 R >>", "<< /Type /Pages /Kids [] /Count 0 >>", "<< /Title (Report) >>"], "/Root 1 0 R /Info 3 0 R");
+    let sound = Document::open(Arc::new(sound)).unwrap();
+    assert_eq!(sound.scan_objects_checked().filter(|(_, o)| o.is_err()).count(), 0);
+    assert!(sound.unreadable_objects().is_empty());
+}
+
+/// A file rebuilt from its object headers still lists an object the scan could not read.
+#[test]
+fn a_rebuilt_file_lists_the_objects_its_scan_could_not_read() {
+    let text = "%PDF-1.7\n1 0 obj\n<< /Type /Catalog /Pages 2 0 R >>\nendobj\n2 0 obj\n<< /Type /Pages /Kids [] /Count 0 >>\nendobj\n3 0 obj\n<< /A ) >>\nendobj\n%%EOF\n";
+    let doc = Document::open(Arc::new(text.as_bytes().to_vec())).unwrap();
+    assert!(doc.repair_log().iter().any(|l| l.starts_with("rebuilt cross-reference index")), "{:?}", doc.repair_log());
+    let lines = doc.unreadable_objects();
+    assert_eq!(lines.len(), 1, "{lines:?}");
+    assert!(lines[0].starts_with("object 3 0 could not be read: syntax error"), "{lines:?}");
+}
+
+/// The list keeps at most 100 objects and then says there were more; an object whose
+/// cross-reference offset holds no object is listed with that as its reason.
+#[test]
+fn the_unreadable_object_list_is_bounded() {
+    let mut bodies = vec!["<< /Type /Catalog /Pages 2 0 R >>", "<< /Type /Pages /Kids [] /Count 0 >>"];
+    bodies.extend(std::iter::repeat_n("<< /A ) >>", 120));
+    let doc = Document::open(Arc::new(build(&bodies, "/Root 1 0 R"))).unwrap();
+    assert_eq!(doc.scan_objects_checked().filter(|(_, o)| o.is_err()).count(), 120);
+    let lines = doc.unreadable_objects();
+    assert_eq!(lines.len(), 101, "{:?}", lines.last());
+    assert!(lines[0].starts_with("object 3 0 could not be read"), "{}", lines[0]);
+    assert_eq!(lines[100], "more objects could not be read; only the first 100 are listed");
+
+    let base = build(&["<< /Type /Catalog /Pages 2 0 R >>", "<< /Type /Pages /Kids [] /Count 0 >>", "(three)"], "/Root 1 0 R");
+    let text = String::from_utf8_lossy(&base).into_owned();
+    let gone = text.replacen("3 0 obj\n(three)", "9 0 obj\n(three)", 1);
+    let doc = Document::open(Arc::new(gone.into_bytes())).unwrap();
+    assert!(doc.try_get(3).is_err());
+    assert_eq!(
+        doc.unreadable_objects(),
+        ["object 3 0 could not be read: no readable copy was found at its cross-reference offset or elsewhere in the file"]
+    );
+}
+
+/// The unreadable list is shared by clones, and each hides what it has edited. A clone that edited
+/// every listed object still lists its own failures: hidden entries don't use up its allowance.
+#[test]
+fn objects_a_clone_edited_do_not_use_up_its_unreadable_allowance() {
+    let mut bodies = vec!["<< /Type /Catalog /Pages 2 0 R >>", "<< /Type /Pages /Kids [] /Count 0 >>"];
+    bodies.extend(std::iter::repeat_n("<< /A ) >>", 110));
+    let doc = Document::open(Arc::new(build(&bodies, "/Root 1 0 R"))).unwrap();
+    for num in 3..103 {
+        assert!(doc.try_get(num).is_err());
+    }
+    assert_eq!(doc.unreadable_objects().len(), 100);
+    let mut edited = doc.clone();
+    for num in 3..103 {
+        edited.set(ObjRef::new(num, 0), Object::Null);
+    }
+    for num in 103..113 {
+        assert!(edited.try_get(num).is_err());
+    }
+    let lines = edited.unreadable_objects();
+    assert_eq!(lines.len(), 10, "{lines:?}");
+    assert!(lines[0].starts_with("object 103 0 could not be read"), "{}", lines[0]);
+    let original = doc.unreadable_objects();
+    assert_eq!(original.len(), 101, "the original still shows at most 100, then says there were more");
+    assert_eq!(original[100], "more objects could not be read; only the first 100 are listed");
+}
+
 #[test]
 fn a_restored_revision_keeps_what_the_saved_file_held_in_object_streams() {
     // The earlier revision: an empty document read back from a file whose catalog and pages

crates/engine/src/document.rs

@@ -631,6 +631,12 @@ impl Document {
     pub fn repair_log(&self) -> Vec<String> {
         self.editor.as_ref().map(|e| e.cos.repair_log().to_vec()).unwrap_or_default()
     }
+
+    /// Objects of the file that could not be read and read as null, one line each (see
+    /// [`pdfcraft_cos::Document::unreadable_objects`]): only those read so far.
+    pub fn unreadable_objects(&self) -> Vec<String> {
+        self.editor.as_ref().map(|e| e.cos.unreadable_objects()).unwrap_or_default()
+    }
 }
 
 /// A title that names no document: what a web browser writes when it saves a blank page or a

parity/acrobat-features.toml

@@ -70,8 +70,8 @@ milestone = "M1"
 status = "shipped"
 commands = []
 tools = ["doc_info"]
-evidence = ["crates/ui-egui/tests/it/viewer.rs::damaged_files_say_they_were_repaired", "crates/cos/tests/it/generations.rs::contradictory_xref_generation_recovers_the_matching_header_and_records_repair", "crates/cos/tests/it/generations.rs::generation_repair_diagnostics_are_bounded_without_disabling_recovery", "crates/cos/tests/it/generations.rs::retained_generation_disagreements_are_reported_in_materialized_mode_too", "crates/cos/tests/it/generations.rs::hybrid_generation_diagnostics_observe_rows_before_the_table_hides_them", "crates/cos/tests/it/generations.rs::discarded_xref_repair_notes_do_not_survive_object_header_reconstruction"]
-notes = "a notice says the file was repaired; Document Properties ▸ Advanced lists the repairs; doc_info reports them. COS records bounded live xref/header generation disagreements on open, including retained materialized and hybrid rows before folding; this follow-up validates the COS policy, without a fresh GUI claim."
+evidence = ["crates/ui-egui/tests/it/viewer.rs::damaged_files_say_they_were_repaired", "crates/cos/tests/it/generations.rs::contradictory_xref_generation_recovers_the_matching_header_and_records_repair", "crates/cos/tests/it/generations.rs::generation_repair_diagnostics_are_bounded_without_disabling_recovery", "crates/cos/tests/it/generations.rs::retained_generation_disagreements_are_reported_in_materialized_mode_too", "crates/cos/tests/it/generations.rs::hybrid_generation_diagnostics_observe_rows_before_the_table_hides_them", "crates/cos/tests/it/generations.rs::discarded_xref_repair_notes_do_not_survive_object_header_reconstruction", "crates/cos/src/document/tests.rs::unreadable_objects_are_listed_with_the_reason", "crates/automation/tests/it/unreadable_objects.rs::doc_info_lists_an_object_that_could_not_be_read"]
+notes = "a notice says the file was repaired; Document Properties ▸ Advanced lists the repairs; doc_info reports them, and lists apart (unreadable_objects) each object that could not be read and reads as null, with its number and why: only objects read so far, including any object a scan, save or audit read, at most 100; a stream whose own data fails to decode is not listed, but the objects of an object stream that cannot be decoded are. COS records bounded live xref/header generation disagreements on open, including retained materialized and hybrid rows before folding; this follow-up validates the COS policy, without a fresh GUI claim."
 
 [[feature]]
 id = "core.xref-streams"