From 761e1ac2122379e0c2cf83079b09b3156f32825b Mon Sep 17 00:00:00 2001
From: Matthew Jackson <1085847+MattJackson@users.noreply.github.com>
Date: Thu, 1 Oct 2026 14:36:10 -0700
Subject: [PATCH 1/8] udf: combine surrogate pairs, sanitise CS0 names, map
 directory extents through the metadata partition, fail short file reads

---
 Cargo.lock |  16 ++++++++
 src/udf.rs | 115 +++++++++++++++++++++++++++++++++++++++++++++++------
 2 files changed, 118 insertions(+), 13 deletions(-)

diff --git a/Cargo.lock b/Cargo.lock
index cf3055a8..f2bdc533 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -854,3 +854,19 @@ dependencies = [
  "log",
  "simd-adler32",
 ]
+
+[[patch.unused]]
+name = "freemkv-engine"
+version = "1.7.7"
+
+[[patch.unused]]
+name = "freemkv-i18n"
+version = "1.7.7"
+
+[[patch.unused]]
+name = "freemkv-keysources"
+version = "1.7.7"
+
+[[patch.unused]]
+name = "libfreemkv"
+version = "1.7.7"
diff --git a/src/udf.rs b/src/udf.rs
index 0a3e21a9..eda5691c 100644
--- a/src/udf.rs
+++ b/src/udf.rs
@@ -139,7 +139,8 @@ pub(crate) struct AbsExtent {
 pub struct DirEntry {
     pub name: String,
     pub is_dir: bool,
-    /// LBA within the metadata partition (add metadata_start for absolute)
+    /// Block within the metadata partition. Not `metadata_start() + meta_lba` when the
+    /// Metadata File is fragmented: later extents live elsewhere on disc.
     pub meta_lba: u32,
     /// File size in bytes (from ICB info_length)
     pub size: u64,
@@ -320,9 +321,15 @@ impl UdfFs {
         }
 
         // Trim to the real file size, or to the requested prefix — whichever is
-        // smaller. If extents under-covered the file (e.g. sparse), leave what
-        // we have rather than over-reporting.
+        // smaller. Extents covering less than that mean a damaged File Entry.
         let trim_to = (entry.size as usize).min(limit);
+        if data.len() < trim_to {
+            return Err(Error::DiscRead {
+                sector: self.partition_start as u64,
+                status: None,
+                sense: None,
+            });
+        }
         if data.len() > trim_to {
             data.truncate(trim_to);
         }
@@ -397,7 +404,7 @@ impl UdfFs {
             if !seen.insert(e.meta_lba) {
                 continue;
             }
-            match self.extents_abs_at(reader, e.meta_lba) {
+            match self.data_extents_abs(reader, e) {
                 Ok(exts) => ranges.extend(
                     exts.iter()
                         .filter(|x| x.recorded && x.len > 0)
@@ -414,6 +421,27 @@ impl UdfFs {
         Ok(merge_ranges(&ranges))
     }
 
+    // A directory's FID data is metadata-partition-relative, a file's physical-partition-relative.
+    fn data_extents_abs(
+        &self,
+        reader: &mut dyn SectorSource,
+        e: &DirEntry,
+    ) -> Result<Vec<AbsExtent>> {
+        if !e.is_dir {
+            return self.extents_abs_at(reader, e.meta_lba);
+        }
+        self.read_icb_extents(reader, e.meta_lba)?
+            .into_iter()
+            .map(|x| {
+                Ok(AbsExtent {
+                    lba: self.meta_to_abs(x.lba)?,
+                    len: x.len,
+                    recorded: x.recorded,
+                })
+            })
+            .collect()
+    }
+
     fn collect_file_ranges(
         &self,
         reader: &mut dyn SectorSource,
@@ -1534,22 +1562,31 @@ fn read_file_size(reader: &mut dyn SectorSource, meta: &MetaMap, meta_lba: u32)
 }
 
 // Decode an OSTA CS0 string: first byte is a compression ID (8 = one byte per code point,
-// i.e. Latin-1; 16 = UTF-16BE). NULs are dropped.
+// i.e. Latin-1; 16 = UTF-16BE, surrogate pairs combined). Control characters (NUL included)
+// are dropped and '/' becomes '_'.
 fn decode_cs0(data: &[u8]) -> String {
     let Some((&comp, rest)) = data.split_first() else {
         return String::new();
     };
     let s: String = match comp {
-        16 => rest
-            .as_chunks::<2>()
-            .0
-            .iter()
-            .filter_map(|&c| char::from_u32(u16::from_be_bytes(c) as u32))
-            .collect(),
+        16 => char::decode_utf16(
+            rest.as_chunks::<2>()
+                .0
+                .iter()
+                .map(|&c| u16::from_be_bytes(c)),
+        )
+        .filter_map(|c| c.ok())
+        .collect(),
         8 => rest.iter().map(|&b| b as char).collect(),
         _ => String::from_utf8_lossy(rest).into_owned(),
     };
-    s.replace('\0', "").trim().to_string()
+    // Names reach error text and logs: no control characters, and '/' would split a path.
+    s.chars()
+        .filter(|c| !c.is_control())
+        .map(|c| if c == '/' { '_' } else { c })
+        .collect::<String>()
+        .trim()
+        .to_string()
 }
 
 // Parse a UDF filename (an OSTA CS0 string).
@@ -1576,7 +1613,8 @@ fn compact_ranges(ranges: &mut Vec<(u32, u32)>, meta_start: u32) -> Result<()> {
 }
 
 /// Merge overlapping or adjacent (start, count) ranges. Caller sorts by start
-/// first. Shared range utility — also used to build the disc's encrypted-content
+/// first; zero-length ranges are kept (unlike `whole_disc::merge_ranges`, which sorts and
+/// drops them). Shared range utility — also used to build the disc's encrypted-content
 /// extent map (see `Disc::encrypted_content_ranges`).
 pub(crate) fn merge_ranges(ranges: &[(u32, u32)]) -> Vec<(u32, u32)> {
     let mut result: Vec<(u32, u32)> = Vec::new();
@@ -6567,6 +6605,57 @@ mod audit_tests {
         );
     }
 
+    #[test]
+    fn utf16_cs0_combines_surrogate_pairs() {
+        // U+1F600 is D83D DE00.
+        assert_eq!(
+            parse_udf_name(&[16, 0, b'A', 0xD8, 0x3D, 0xDE, 0x00]),
+            "A\u{1F600}"
+        );
+    }
+
+    #[test]
+    fn cs0_names_carry_no_control_characters_or_slashes() {
+        assert_eq!(
+            parse_udf_name(&[8, b'a', 0x1B, b'[', b'2', b'J', b'/', b'b']),
+            "a[2J_b"
+        );
+    }
+
+    #[test]
+    fn read_file_fails_when_extents_cover_less_than_the_declared_size() {
+        let mut r = GenReader::new(0);
+        let mut icb = efe(8);
+        put_ad(&mut icb, 0, 2048, 10);
+        r.over.insert(5, icb);
+        let mut f = file("F", 5);
+        f.size = 8192;
+        let fs = fs_of(0, 1, vec![f]);
+        assert!(matches!(
+            fs.read_file(&mut r, "/F"),
+            Err(Error::DiscRead { .. })
+        ));
+    }
+
+    #[test]
+    fn non_stream_ranges_map_directory_data_through_the_metadata_partition() {
+        let mut r = GenReader::new(0);
+        let mut icb = efe(8);
+        put_ad(&mut icb, 0, 2048, 3);
+        r.over.insert(105, icb);
+        let mut dir = file("D", 5);
+        dir.is_dir = true;
+        let mut fs = fs_of(100, 1, vec![dir]);
+        fs.partition_start = 5000;
+        let ranges = fs.non_stream_ranges(&mut r).expect("ranges");
+        let covers = |lba: u32| ranges.iter().any(|&(s, n)| (s..s + n).contains(&lba));
+        assert!(
+            covers(103),
+            "directory data sits at metadata block 3: {ranges:?}"
+        );
+        assert!(!covers(5003), "not at partition_start + 3: {ranges:?}");
+    }
+
     #[test]
     fn eight_bit_cs0_is_latin1() {
         assert_eq!(parse_udf_name(&[8, 0xE9, b'A']), "\u{e9}A");

From 6ddadda5ddc77bd5c765856d0536bb1f4f5cd986 Mon Sep 17 00:00:00 2001
From: Matthew Jackson <1085847+MattJackson@users.noreply.github.com>
Date: Thu, 1 Oct 2026 14:37:08 -0700
Subject: [PATCH 2/8] udf: tests for non-stream ranges and FUA bypass

---
 src/udf.rs | 82 ++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 82 insertions(+)

diff --git a/src/udf.rs b/src/udf.rs
index eda5691c..a9eb2549 100644
--- a/src/udf.rs
+++ b/src/udf.rs
@@ -6605,6 +6605,88 @@ mod audit_tests {
         );
     }
 
+    // Marks sector data by which entry point served it; forwards the trait's extras.
+    struct Probe {
+        unmapped: Vec<crate::sector::bus_removal::UnmappedStreamFile>,
+    }
+
+    impl SectorSource for Probe {
+        fn read_sectors(&mut self, _: u32, count: u16, buf: &mut [u8], _: bool) -> Result<usize> {
+            buf[..count as usize * 2048].fill(0x11);
+            Ok(count as usize * 2048)
+        }
+        fn read_sectors_fua(
+            &mut self,
+            lba: u32,
+            count: u16,
+            buf: &mut [u8],
+            recovery: bool,
+            fua: bool,
+        ) -> Result<usize> {
+            if fua {
+                buf[..count as usize * 2048].fill(0x22);
+                return Ok(count as usize * 2048);
+            }
+            self.read_sectors(lba, count, buf, recovery)
+        }
+        fn unmapped_stream_files(&self) -> &[crate::sector::bus_removal::UnmappedStreamFile] {
+            &self.unmapped
+        }
+        fn random_access(&self) -> bool {
+            false
+        }
+    }
+
+    #[test]
+    fn buffered_reader_sends_a_fua_read_to_the_medium_and_forwards_the_source_traits() {
+        let mut inner = Probe {
+            unmapped: vec![crate::sector::bus_removal::UnmappedStreamFile::new(
+                "/BDMV/STREAM/00001.m2ts".into(),
+                7,
+                &Error::Halted,
+            )],
+        };
+        let mut br = BufferedSectorReader::new(&mut inner, 8);
+        let mut buf = [0u8; 2048];
+        br.read_sectors(100, 1, &mut buf, true).unwrap();
+        assert_eq!(buf[0], 0x11);
+        br.read_sectors_fua(100, 1, &mut buf, true, true).unwrap();
+        assert_eq!(
+            buf[0], 0x22,
+            "a FUA read must not be answered from the cache"
+        );
+        assert!(!br.random_access());
+        assert_eq!(br.unmapped_stream_files().len(), 1);
+    }
+
+    #[test]
+    fn non_stream_ranges_cover_structures_and_non_stream_data_only() {
+        let mut r = GenReader::new(0);
+        let mut a = efe(16);
+        put_ad(&mut a, 0, 2048, 20);
+        put_ad(&mut a, 1, 2048 | (1 << 30), 700);
+        r.over.insert(300, a);
+        let mut s = efe(8);
+        put_ad(&mut s, 0, 10 * 2048, 9000);
+        r.over.insert(103, s);
+        let dir = |name: &str, meta_lba, entries| DirEntry {
+            name: name.into(),
+            is_dir: true,
+            meta_lba,
+            size: 0,
+            entries,
+        };
+        let stream = dir("STREAM", 2, vec![file("00000.m2ts", 3)]);
+        let bdmv = dir("BDMV", 1, vec![stream, file("a.bin", 4)]);
+        let mut fs = fs_of(100, 8, vec![bdmv]);
+        fs.meta = MetaMap(vec![(100, 4), (300, 4)]);
+        fs.partition_start = 50;
+        assert_eq!(
+            fs.non_stream_ranges(&mut r).expect("ranges"),
+            vec![(0, 50), (70, 1), (100, 8), (300, 4)]
+        );
+    }
+
     #[test]
     fn utf16_cs0_combines_surrogate_pairs() {
         // U+1F600 is D83D DE00.

From 1a3e56f8c73e4cba1148e37811527cbc449dde76 Mon Sep 17 00:00:00 2001
From: Matthew Jackson <1085847+MattJackson@users.noreply.github.com>
Date: Thu, 1 Oct 2026 14:38:10 -0700
Subject: [PATCH 3/8] bdnav: GOTO/BREAK/PLAY/SETSYSTEM tests; doc fixes in pes,
 consts, golden helper

---
 src/bdnav/vm.rs         | 36 ++++++++++++++++++++++++++++++++++++
 src/consts.rs           |  4 ++--
 src/pes.rs              | 10 +++++-----
 src/test_util_golden.rs |  2 +-
 4 files changed, 44 insertions(+), 8 deletions(-)

diff --git a/src/bdnav/vm.rs b/src/bdnav/vm.rs
index c335ac11..b73faa2d 100644
--- a/src/bdnav/vm.rs
+++ b/src/bdnav/vm.rs
@@ -522,6 +522,42 @@ mod tests {
         assert_eq!(resolve(&index, &mobjs, &|_| true), None);
     }
 
+    #[test]
+    fn goto_lands_on_its_target_and_break_terminates() {
+        // op_cnt=1, grp=BRANCH(0), sub_grp=GOTO(0), imm dst; branch_opt GOTO(1) / BREAK(2).
+        let goto = |line: u32| cmd(1 << 5, 0x81, 0, 0, line, 0);
+        let brk = cmd(1 << 5, 0x82, 0, 0, 0, 0);
+        let index = idx(PlaybackObj::Hdmv { id_ref: 0 }, vec![]);
+        // GOTO line 2 jumps over the logo PlayPL 99 (a candidate) to the feature PlayPL 1.
+        let d = build(&[&[goto(2), play_pl(99), play_pl(1)]]);
+        let mobjs = mobj::parse(&d).unwrap();
+        assert_eq!(resolve(&index, &mobjs, &|_| true), Some(1));
+        let d = build(&[&[brk, play_pl(1)]]);
+        let mobjs = mobj::parse(&d).unwrap();
+        assert_eq!(resolve(&index, &mobjs, &|_| true), None);
+    }
+
+    #[test]
+    fn only_the_play_pl_family_emits_a_playlist() {
+        // sub_grp=PLAY(2); branch_opt 3 is Terminate/Link, which never plays dst.
+        let d = build(&[&[cmd((1 << 5) | 2, 0x83, 0, 0, 11, 0)]]);
+        let mobjs = mobj::parse(&d).unwrap();
+        let index = idx(PlaybackObj::Hdmv { id_ref: 0 }, vec![]);
+        assert_eq!(resolve(&index, &mobjs, &|_| true), None);
+    }
+
+    #[test]
+    fn setsystem_does_not_execute_as_a_gpr_set() {
+        // grp=SET(2), sub_grp=SETSYSTEM(1), set_opt=MOVE(1): must not write GPR5.
+        let setsys = cmd((2 << 5) | (2 << 3) | 1, 0x40, 0, 0x01, 5, 77);
+        let d = build(&[&[setsys]]);
+        let mobjs = mobj::parse(&d).unwrap();
+        let index = idx(PlaybackObj::Hdmv { id_ref: 0 }, vec![]);
+        let mut vm = Vm::new(&mobjs, &index);
+        assert_eq!(run(&mut vm, 0, &|_| false), None);
+        assert_eq!(vm.gpr[5], 0);
+    }
+
     #[test]
     fn swap_immediate_operand_is_not_written_back() {
         // SWAP dst=GPR0 with src=IMMEDIATE 5 (imm_op1=0, imm_op2=1) must refuse
diff --git a/src/consts.rs b/src/consts.rs
index c134e8b4..90392782 100644
--- a/src/consts.rs
+++ b/src/consts.rs
@@ -105,7 +105,7 @@ pub mod coding_type {
 /// 13818-1 Table 2-22). Shared by the program-stream demuxer and the TS/M2TS
 /// muxers, so defined here once. Each is `u8` (matches the byte on the wire).
 pub mod pes_stream_id {
-    /// Video stream (`110x xxxx`; freemkv emits the base id `0xE0`).
+    /// Video stream (`1110 xxxx`; freemkv emits the base id `0xE0`).
     pub const VIDEO: u8 = 0xE0;
     /// MPEG audio stream (`110x xxxx`; 11172-3/13818-3/13818-7, freemkv emits `0xC0`).
     pub const MPEG_AUDIO: u8 = 0xC0;
@@ -122,7 +122,7 @@ pub mod pes_stream_id {
     /// private_stream_2 — DVD navigation (PCI/DSI); carries no muxable ES.
     pub const PRIVATE_STREAM_2: u8 = 0xBF;
 
-    /// Highest video stream_id — the `110x xxxx` video range tops out at 0xEF.
+    /// Highest video stream_id — the `1110 xxxx` video range tops out at 0xEF.
     pub const VIDEO_MAX: u8 = 0xEF;
 
     /// Inclusive range of every PES `stream_id` that carries demuxable payload:
diff --git a/src/pes.rs b/src/pes.rs
index a0252c9a..0e503650 100644
--- a/src/pes.rs
+++ b/src/pes.rs
@@ -1,10 +1,10 @@
-//! Stream — read PES frames in, write PES frames out.
+//! PES frames — the unit that moves between an input and an output.
 //!
-//! A stream is a stream. You read() from it or write() to it.
-//! The stream handles its own format internally.
+//! A [`PesSource`] yields frames with `read()`; a [`PesSink`] takes them with `write()`.
+//! Each handles its own format internally.
 //!
-//! disc.read()  → PES frame (sectors → decrypt → demux internally)
-//! mkv.write(frame) → MKV file (mux internally)
+//! source.read()     → PES frame (sectors → decrypt → demux internally)
+//! sink.write(frame) → output file or wire (mux internally)
 
 // Shared by `serialize`/`deserialize` so the wire format round-trips.
 // Oversized frames are rejected on write rather than hard-erroring
diff --git a/src/test_util_golden.rs b/src/test_util_golden.rs
index 5ed59be7..b3b1bb53 100644
--- a/src/test_util_golden.rs
+++ b/src/test_util_golden.rs
@@ -37,7 +37,7 @@ impl Golden {
         self
     }
 
-    /// Record the length and SHA-256 of `bytes` under `key`.
+    /// Record the length and the first 16 bytes (hex) of the SHA-256 of `bytes` under `key`.
     pub fn bytes(&mut self, key: &str, bytes: &[u8]) -> &mut Self {
         use sha2::{Digest, Sha256};
         let digest: String = Sha256::digest(bytes)

From 69329b29ca7570df6650f6dae8a943474ba40ec9 Mon Sep 17 00:00:00 2001
From: Matthew Jackson <1085847+MattJackson@users.noreply.github.com>
Date: Thu, 1 Oct 2026 14:39:04 -0700
Subject: [PATCH 4/8] clpi, bdjo: tests for short sci and NUL-padded app
 strings

---
 src/bdnav/bdjo.rs | 14 ++++++++++++++
 src/clpi.rs       | 14 ++++++++++++++
 2 files changed, 28 insertions(+)

diff --git a/src/bdnav/bdjo.rs b/src/bdnav/bdjo.rs
index 92f03504..8dc0a383 100644
--- a/src/bdnav/bdjo.rs
+++ b/src/bdnav/bdjo.rs
@@ -397,6 +397,20 @@ mod tests {
         }
     }
 
+    #[test]
+    fn app_strings_drop_trailing_nul_padding() {
+        let bytes = build_bdjo(&[AppSpec {
+            control_code: 1,
+            base_dir: "0000\0",
+            classpath_extension: "",
+            initial_class: "a.B\0\0",
+        }]);
+        let apps = parse(&bytes).expect("parses");
+        assert_eq!(apps[0].base_directory, "0000");
+        assert_eq!(apps[0].initial_class, "a.B");
+        assert_eq!(apps[0].jar_ids(), vec!["0000"]);
+    }
+
     #[test]
     fn parses_autostart_app_fqcn_and_jar_ids() {
         let bytes = build_bdjo(&[AppSpec {
diff --git a/src/clpi.rs b/src/clpi.rs
index 3a185782..45755092 100644
--- a/src/clpi.rs
+++ b/src/clpi.rs
@@ -293,6 +293,20 @@ mod tests {
         assert_eq!(clip.streams[0].language, "eng");
     }
 
+    /// An audio or TextST sci shorter than 5 bytes has no language field: the stream is
+    /// kept, the language stays empty, and nothing indexes past the sci.
+    #[test]
+    fn program_info_short_audio_and_textst_sci_keep_the_stream_without_a_language() {
+        let pi = build_program_info(&[
+            (0x1100, vec![0x83u8, 0x61, b'e', b'n']),
+            (0x1200, vec![0x92u8, 0x01, b'e', b'n']),
+        ]);
+        let data = build_clpi_with_proginfo(100, &pi, None);
+        let clip = parse(&data).expect("should parse");
+        assert_eq!(clip.streams.len(), 2);
+        assert!(clip.streams.iter().all(|s| s.language.is_empty()));
+    }
+
     /// ProgramInfo PG (0x90)/IG (0x91): layout is coding_type(1)+lang(3),
     /// so language is at sci[1..4] (NOT sci[2..5] like audio). Verify the
     /// PG arm reads from the right offset.

From 18060529a9dea07f5f65f7ad29415a0502248541 Mon Sep 17 00:00:00 2001
From: Matthew Jackson <1085847+MattJackson@users.noreply.github.com>
Date: Thu, 1 Oct 2026 14:42:50 -0700
Subject: [PATCH 5/8] error: escape disc-derived names in Display; use code
 constants in the kind map

---
 src/error.rs | 62 ++++++++++++++++++++++++++++++++++++++++------------
 src/udf.rs   | 12 +++++-----
 2 files changed, 54 insertions(+), 20 deletions(-)

diff --git a/src/error.rs b/src/error.rs
index bfab7c94..ece6ccfc 100644
--- a/src/error.rs
+++ b/src/error.rs
@@ -1253,8 +1253,10 @@ impl std::fmt::Display for Error {
                 (None, None) => write!(f, "E{}: {}", self.code(), sector),
             },
             Error::Halted => write!(f, "E{}", self.code()),
-            Error::UdfNotFound { path } => write!(f, "E{}: {}", self.code(), path),
-            Error::UdfUnrecordedExtent { path } => write!(f, "E{}: {}", self.code(), path),
+            // Disc- or backup-folder-derived names: escape control characters.
+            Error::UdfNotFound { path } | Error::UdfUnrecordedExtent { path } => {
+                write!(f, "E{}: {}", self.code(), path.escape_debug())
+            }
             Error::SeamPlanDroppedMost { dropped, written } => {
                 write!(f, "E{} {dropped}/{written}", self.code())
             }
@@ -1265,7 +1267,7 @@ impl std::fmt::Display for Error {
             | Error::DirImageFileChanged { path }
             | Error::DirNameTooLong { path }
             | Error::DirImageFanout { path } => {
-                write!(f, "E{}: {}", self.code(), path)
+                write!(f, "E{}: {}", self.code(), path.escape_debug())
             }
             Error::DiscTitleRange { index, count } => {
                 write!(f, "E{}: {}/{}", self.code(), index, count)
@@ -1331,8 +1333,10 @@ impl std::fmt::Display for Error {
             Error::TimedOut { op } | Error::WorkerLost { op } => {
                 write!(f, "E{}: {op}", self.code())
             }
-            Error::BusStreamUnmapped { files } => write!(f, "E{}: {files}", self.code()),
-            Error::ImageScoped { path } => write!(f, "E{}: {path}", self.code()),
+            Error::BusStreamUnmapped { files } => {
+                write!(f, "E{}: {}", self.code(), files.escape_debug())
+            }
+            Error::ImageScoped { path } => write!(f, "E{}: {}", self.code(), path.escape_debug()),
             Error::RemuxVerifyFailed { kind, path } => match kind {
                 RemuxVerifyKind::RuntimeMismatch {
                     have_secs,
@@ -1409,21 +1413,21 @@ impl From<Error> for std::io::Error {
             9000..=9001 => std::io::ErrorKind::Unsupported,
             9002..=9008 => std::io::ErrorKind::InvalidInput,
             // 9010 HevcParamParse: malformed hvcC payload.
-            9010 => std::io::ErrorKind::InvalidData,
+            E_HEVC_PARAM_PARSE => std::io::ErrorKind::InvalidData,
             // 9011 MuxTrackRange: caller passed a bad track index.
-            9011 => std::io::ErrorKind::InvalidInput,
+            E_MUX_TRACK_RANGE => std::io::ErrorKind::InvalidInput,
             // 9012 Fmp4Unimplemented: sink can't emit media yet.
-            9012 => std::io::ErrorKind::Unsupported,
+            E_FMP4_UNIMPLEMENTED => std::io::ErrorKind::Unsupported,
             // 9014 PipelineJoinTimeout: consumer drain exceeded deadline.
             E_PIPELINE_JOIN_TIMEOUT => std::io::ErrorKind::TimedOut,
             // 9017 PesTrackTooLarge: out-of-range track index on serialize.
-            9017 => std::io::ErrorKind::InvalidInput,
+            E_PES_TRACK_TOO_LARGE => std::io::ErrorKind::InvalidInput,
             // 9020 DiscCapacityOverflow: disc reported a capacity sentinel
             // we can't represent — treat as bad/invalid device data.
-            9020 => std::io::ErrorKind::InvalidData,
+            E_DISC_CAPACITY_OVERFLOW => std::io::ErrorKind::InvalidData,
             // 9021 M2tsPacketMalformed: a muxer invariant break produced
             // a non-188-byte packet — treat as invalid data.
-            9021 => std::io::ErrorKind::InvalidData,
+            E_M2TS_PACKET_MALFORMED => std::io::ErrorKind::InvalidData,
             // 9022 NetworkAddrBlocked: the output host resolved only to
             // invalid (unspecified/multicast/broadcast/reserved) addresses.
             E_NETWORK_ADDR_BLOCKED => std::io::ErrorKind::PermissionDenied,
@@ -1440,7 +1444,7 @@ impl From<Error> for std::io::Error {
             // truncated — invalid input data.
             E_MKV_SOURCE_INVALID => std::io::ErrorKind::InvalidData,
             // 9054 MkvUnencodable: the writer was asked for an element size EBML
-            // cannot represent. An output-side limit, not bad input.
+            // cannot represent; the data it was given cannot be encoded.
             E_MKV_UNENCODABLE => std::io::ErrorKind::InvalidData,
             // mp4:// demux errors: a malformed/truncated source file
             // (E_MP4_INVALID), or a source whose tracks the mux can't use — no
@@ -1457,10 +1461,10 @@ impl From<Error> for std::io::Error {
             E_SYNC_TIMEOUT | E_SYNC_WORKER_LOST => std::io::ErrorKind::TimedOut,
             // 9030 ExtentNotUnitAligned: a malformed/non-AACS-aligned
             // extent was handed to the prefetch producer.
-            9030 => std::io::ErrorKind::InvalidInput,
+            E_EXTENT_NOT_UNIT_ALIGNED => std::io::ErrorKind::InvalidInput,
             // 9047 DiscCapacityMalformed: the drive returned an unusable
             // READ CAPACITY response (short transfer / overflow).
-            9047 => std::io::ErrorKind::InvalidData,
+            E_DISC_CAPACITY_MALFORMED => std::io::ErrorKind::InvalidData,
             // dir:// usage / footgun gates (9019, 9024–9026, 9028): the caller
             // gave an invalid flag/source/name combination — InvalidInput.
             E_DIR_RAW_REJECTED
@@ -1787,6 +1791,36 @@ mod tests {
         assert!(shown.contains("A\\u{1b}[2JB\\n"), "{shown}");
     }
 
+    #[test]
+    fn disc_derived_names_cannot_inject_terminal_escapes_via_display() {
+        let n = || "A\x1b[2JB".to_string();
+        let errors = [
+            Error::UdfNotFound { path: n() },
+            Error::UdfUnrecordedExtent { path: n() },
+            Error::DirImagePlacement { path: n() },
+            Error::DirImageFileChanged { path: n() },
+            Error::DirNameTooLong { path: n() },
+            Error::DirImageFanout { path: n() },
+            Error::BusStreamUnmapped { files: n() },
+            Error::ImageScoped { path: n() },
+        ];
+        for e in errors {
+            let shown = e.to_string();
+            assert!(!shown.chars().any(char::is_control), "{shown:?}");
+            assert_eq!(shown, format!("E{}: A\\u{{1b}}[2JB", e.code()));
+        }
+    }
+
+    #[test]
+    fn image_ends_before_read_display_is_lba_then_have_slash_want() {
+        let e = Error::ImageEndsBeforeRead {
+            lba: 111,
+            have: 222,
+            want: 333,
+        };
+        assert_eq!(e.to_string(), format!("E{}: 111 222/333", e.code()));
+    }
+
     #[test]
     fn new_variants_have_distinct_codes() {
         let codes = [
diff --git a/src/udf.rs b/src/udf.rs
index a9eb2549..a97d9d64 100644
--- a/src/udf.rs
+++ b/src/udf.rs
@@ -1563,7 +1563,7 @@ fn read_file_size(reader: &mut dyn SectorSource, meta: &MetaMap, meta_lba: u32)
 
 // Decode an OSTA CS0 string: first byte is a compression ID (8 = one byte per code point,
 // i.e. Latin-1; 16 = UTF-16BE, surrogate pairs combined). Control characters (NUL included)
-// are dropped and '/' becomes '_'.
+// are dropped.
 fn decode_cs0(data: &[u8]) -> String {
     let Some((&comp, rest)) = data.split_first() else {
         return String::new();
@@ -1580,10 +1580,10 @@ fn decode_cs0(data: &[u8]) -> String {
         8 => rest.iter().map(|&b| b as char).collect(),
         _ => String::from_utf8_lossy(rest).into_owned(),
     };
-    // Names reach error text and logs: no control characters, and '/' would split a path.
+    // Names reach error text and logs: no control characters. A '/' is kept so the
+    // structure-file filter still rejects the name.
     s.chars()
         .filter(|c| !c.is_control())
-        .map(|c| if c == '/' { '_' } else { c })
         .collect::<String>()
         .trim()
         .to_string()
@@ -6697,10 +6697,10 @@ mod audit_tests {
     }
 
     #[test]
-    fn cs0_names_carry_no_control_characters_or_slashes() {
+    fn cs0_names_carry_no_control_characters() {
         assert_eq!(
-            parse_udf_name(&[8, b'a', 0x1B, b'[', b'2', b'J', b'/', b'b']),
-            "a[2J_b"
+            parse_udf_name(&[8, b'a', 0x1B, b'[', b'2', b'J', b'b']),
+            "a[2Jb"
         );
     }
 

From 58c1191dd1832a79ac55ecb4c31180d1f96087c1 Mon Sep 17 00:00:00 2001
From: Matthew Jackson <1085847+MattJackson@users.noreply.github.com>
Date: Thu, 1 Oct 2026 14:44:21 -0700
Subject: [PATCH 6/8] dvdnav: tests for counter-mode, rnd/swap taint and
 link-code range

---
 src/dvdnav/nav.rs   | 45 ++++++++++++++++++++++++++++++++++++++++++++-
 src/dvdnav/vmcmd.rs |  9 +++++++++
 2 files changed, 53 insertions(+), 1 deletion(-)

diff --git a/src/dvdnav/nav.rs b/src/dvdnav/nav.rs
index 164bb70b..f411891f 100644
--- a/src/dvdnav/nav.rs
+++ b/src/dvdnav/nav.rs
@@ -345,7 +345,7 @@ fn run_first_play(cmds: &[[u8; 8]]) -> Option<u8> {
             } => {
                 if tainted {
                     vm.taint_gprm(reg);
-                    if op == 2 {
+                    if op == SET_SWAP {
                         vm.taint_gprm(src); // swap also writes its source
                     }
                 } else {
@@ -611,6 +611,49 @@ mod tests {
         assert_eq!(resolve_from_vmg(&vmgi), None);
     }
 
+    // SetGPRMMD counter mode makes a GPRM time-dependent: a compare on it must abstain,
+    // including when the mode was set by a line whose own predicate was false.
+    #[test]
+    fn counter_mode_gprm_makes_a_later_compare_abstain() {
+        // 53 .. imm 5, b5 = 0x83: counter bit + g3. Then `if g3 == g3 -> JumpTT 1`.
+        let cmp = h("3022000000010303");
+        for set in ["5300000500830000", "5330000500830000"] {
+            let vmgi = build_vmgi(&[h(set), cmp], 1, &[(2, 1)]);
+            assert_eq!(resolve_from_vmg(&vmgi), None, "{set}");
+        }
+        // Counter bit clear: the compare is decidable.
+        let vmgi = build_vmgi(&[h("5300000500030000"), cmp], 1, &[(2, 1)]);
+        assert!(resolve_from_vmg(&vmgi).is_some());
+    }
+
+    // SetGPRMMD stores like a mov: the immediate (bytes 2-3) and source register (byte 3)
+    // land in the register named by byte 5.
+    #[test]
+    fn setgprmmd_stores_its_immediate_and_source_register() {
+        // g1 = 9; SetGPRMMD g2 = imm 9 / g2 = g1; then `if g2 == g1 -> JumpTT 1`.
+        let jump = h("3022000000010201");
+        for md in ["5300000900020000", "4300000100020000"] {
+            let vmgi = build_vmgi(&[h("7100000100090000"), h(md), jump], 1, &[(2, 1)]);
+            assert!(resolve_from_vmg(&vmgi).is_some(), "{md}");
+        }
+    }
+
+    // A random value is never decidable, and a swap under an undecidable guard leaves
+    // its source register unknown too.
+    #[test]
+    fn rnd_and_guarded_swap_taint_their_registers() {
+        let mut vm = Vm::new();
+        vm.set(0, SET_RND, true, 1, 0);
+        assert!(vm.reg_tainted(0));
+        // line 0: swap g0,g1 guarded by an SPRM compare; line 1: `if g1 == g1 -> JumpTT 1`.
+        let vmgi = build_vmgi(
+            &[h("6220800000010000"), h("3022000000010101")],
+            1,
+            &[(2, 1)],
+        );
+        assert_eq!(resolve_from_vmg(&vmgi), None);
+    }
+
     // A SetSystem (SPRM write, type 2) in the First-Play list is a no-op FOR
     // RESOLUTION: it must keep executing, not abort, so a following JumpTT still
     // resolves. `40..` = type 2, zero compare nibble → unconditional.
diff --git a/src/dvdnav/vmcmd.rs b/src/dvdnav/vmcmd.rs
index b7a9dec3..1f9a9b96 100644
--- a/src/dvdnav/vmcmd.rs
+++ b/src/dvdnav/vmcmd.rs
@@ -337,6 +337,15 @@ mod tests {
         assert!(!decode(&h("7101000000010011")).link, "sub-op 0x11 is not");
     }
 
+    // Every link code from LinkPGCN through LinkCN leaves the pre list; neighbours do not.
+    #[test]
+    fn set_link_flag_covers_linkpgcn_through_linkcn() {
+        for (cmd, link) in [(3, false), (4, true), (5, true), (6, true), (7, true), (8, false)] {
+            let c = decode(&h(&format!("710{cmd:x}000000000001")));
+            assert_eq!(c.link, link, "cmd {cmd}");
+        }
+    }
+
     // Special sub-command 3 (SetTmpPML) sets SPRM13 then gotos byte7 when cond holds.
     #[test]
     fn set_tmp_pml_decodes_as_goto() {

From 9f913b7db87b99c52aecf8fd610c9aa8692201d7 Mon Sep 17 00:00:00 2001
From: Matthew Jackson <1085847+MattJackson@users.noreply.github.com>
Date: Thu, 1 Oct 2026 14:48:16 -0700
Subject: [PATCH 7/8] ifo: fall back to the BUP when the IFO keeps fewer
 titles, bound chapter cells, tests

---
 src/dvdnav/vmcmd.rs |   9 ++-
 src/ifo.rs          | 143 +++++++++++++++++++++++++++++++++++++++++---
 2 files changed, 142 insertions(+), 10 deletions(-)

diff --git a/src/dvdnav/vmcmd.rs b/src/dvdnav/vmcmd.rs
index 1f9a9b96..167902cb 100644
--- a/src/dvdnav/vmcmd.rs
+++ b/src/dvdnav/vmcmd.rs
@@ -340,7 +340,14 @@ mod tests {
     // Every link code from LinkPGCN through LinkCN leaves the pre list; neighbours do not.
     #[test]
     fn set_link_flag_covers_linkpgcn_through_linkcn() {
-        for (cmd, link) in [(3, false), (4, true), (5, true), (6, true), (7, true), (8, false)] {
+        for (cmd, link) in [
+            (3, false),
+            (4, true),
+            (5, true),
+            (6, true),
+            (7, true),
+            (8, false),
+        ] {
             let c = decode(&h(&format!("710{cmd:x}000000000001")));
             assert_eq!(c.link, link, "cmd {cmd}");
         }
diff --git a/src/ifo.rs b/src/ifo.rs
index 0d4d28dc..c1373fbb 100644
--- a/src/ifo.rs
+++ b/src/ifo.rs
@@ -519,7 +519,8 @@ pub(crate) fn parse_tt_srpt(
 
 // ── VTS parser ──────────────────────────────────────────────────────────────
 
-/// Parse VTS_XX_0.IFO for one title set, falling back to its VTS_XX_0.BUP copy.
+/// Parse VTS_XX_0.IFO for one title set, falling back to its VTS_XX_0.BUP copy when the
+/// IFO fails or keeps fewer titles than `titles_info` declares.
 ///
 /// `titles_info` is a list of (chapter_count, vts_title_number) from TT_SRPT.
 fn parse_vts(
@@ -529,19 +530,30 @@ fn parse_vts(
     titles_info: &[(u16, u8)],
 ) -> Result<DvdTitleSet> {
     let path = format!("/VIDEO_TS/VTS_{vts_number:02}_0.IFO");
-    let err = match parse_vts_file(reader, udf, &path, &path, vts_number, titles_info) {
-        Ok(ts) => return Ok(ts),
+    let mut partial = None;
+    let mut err = None;
+    match parse_vts_file(reader, udf, &path, &path, vts_number, titles_info) {
+        Ok(ts) if ts.titles.len() >= titles_info.len() => return Ok(ts),
+        Ok(ts) => partial = Some(ts),
         Err(Error::Halted) => return Err(Error::Halted),
-        Err(e) => e,
-    };
+        Err(e) => err = Some(e),
+    }
     let bup = format!("/VIDEO_TS/VTS_{vts_number:02}_0.BUP");
     match parse_vts_file(reader, udf, &bup, &path, vts_number, titles_info) {
-        Ok(ts) => {
-            tracing::warn!(target: "freemkv::scan", vts = vts_number, code = err.code(), "VTS IFO bad; using BUP");
+        Ok(ts)
+            if partial
+                .as_ref()
+                .is_none_or(|p| ts.titles.len() > p.titles.len()) =>
+        {
+            tracing::warn!(target: "freemkv::scan", vts = vts_number, "VTS IFO bad; using BUP");
             Ok(ts)
         }
         Err(Error::Halted) => Err(Error::Halted),
-        Err(_) => Err(err),
+        _ => match (partial, err) {
+            (Some(ts), _) => Ok(ts),
+            (None, Some(e)) => Err(e),
+            (None, None) => Err(Error::IfoParse),
+        },
     }
 }
 
@@ -1030,7 +1042,8 @@ pub(crate) fn parse_pgc(data: &[u8], pgc_offset: usize, chapters: u16) -> Result
             let cell_base = pgc_offset + cell_playback_offset;
             for i in 0..num_cells {
                 let co = cell_base + i * 24;
-                if co + 8 > data.len() {
+                // Same bound as the cell loop above: a cell that is not kept adds nothing.
+                if co + 24 > data.len() {
                     cell_frames.push((0, 0.0));
                     continue;
                 }
@@ -2448,6 +2461,25 @@ mod tests {
         assert_eq!(title.chapter_times, vec![0.0, 10.01]);
     }
 
+    // A cell cut off mid-record is not in `cells`, so it adds no time to a chapter mark.
+    #[test]
+    fn pgc_chapter_times_ignore_a_cell_cut_off_mid_record() {
+        let mut pgc = build_pgc(
+            bcd_secs(59),
+            &[
+                (0x00, bcd_secs(10), 0, 9),
+                (0x00, bcd_secs(20), 10, 19),
+                (0x00, bcd_secs(31), 20, 29),
+            ],
+            &[1, 3],
+            None,
+        );
+        pgc.truncate(0xEA + 2 + 24 + 12);
+        let title = parse_pgc(&pgc, 0, 2).unwrap();
+        assert_eq!(title.cells.len(), 1);
+        assert_eq!(title.chapter_times, vec![0.0, 10.01]);
+    }
+
     // A program map running past the end of the data must stop at the buffer
     // end. Fixture map begins at PGC+0xEA, buffer holds 50 bytes from there,
     // so a declared 255 programs must yield exactly 50 chapter times.
@@ -2752,6 +2784,34 @@ mod tests {
         d
     }
 
+    // The title number and its entry offset are both bounded by the table: bytes beyond
+    // it are never read as a PGCN. The table sits at byte 8 (offset 0 means absent).
+    #[test]
+    fn ptt_srpt_pgc_index_stays_inside_the_table() {
+        let put =
+            |d: &mut Vec<u8>, at: usize, v: &[u8]| d[8 + at..8 + at + v.len()].copy_from_slice(v);
+        let mut d = vec![0u8; 8 + 24];
+        put(&mut d, 0, &1u16.to_be_bytes());
+        put(&mut d, 4, &23u32.to_be_bytes());
+        put(&mut d, 8, &16u32.to_be_bytes());
+        put(&mut d, 12, &20u32.to_be_bytes());
+        put(&mut d, 16, &3u16.to_be_bytes());
+        put(&mut d, 20, &9u16.to_be_bytes());
+        assert_eq!(ptt_srpt_pgc_index(&d, 8, 1), Some(2));
+        assert_eq!(
+            ptt_srpt_pgc_index(&d, 8, 2),
+            None,
+            "title 2 is past the count"
+        );
+        // The declared table ends before the entry.
+        put(&mut d, 4, &15u32.to_be_bytes());
+        assert_eq!(
+            ptt_srpt_pgc_index(&d, 8, 1),
+            None,
+            "entry outside the table"
+        );
+    }
+
     #[test]
     fn ptt_srpt_counts_the_pgcs_a_title_spans() {
         // Title 1: one PTT per PGC (1, 2, 3); title 2: two PTTs in PGC 4.
@@ -2959,6 +3019,71 @@ mod tests {
         assert_eq!(ts.titles[0].duration_secs, 22.022, "TTN 1 -> PGC 2 via PTT");
     }
 
+    fn bup_fixture() -> (Vec<u8>, Vec<u8>) {
+        let two = vec![
+            build_pgc(bcd_secs(11), &[(0x00, bcd_secs(11), 0, 9)], &[], None),
+            build_pgc(bcd_secs(22), &[(0x00, bcd_secs(22), 50, 59)], &[], None),
+        ];
+        let good = build_vts_ifo(0, 0, &two, None);
+        let mut bad = good.clone();
+        bad[0] = b'X';
+        (bad, good)
+    }
+
+    /// A bad IFO falls back to the BUP, but the title VOBS stay anchored on the IFO's LBA.
+    #[test]
+    fn parse_vts_falls_back_to_the_bup_and_anchors_on_the_ifo() {
+        let (bad, good) = bup_fixture();
+        let (mut disc, udf) = video_ts_disc(vec![("VTS_01_0.IFO", bad), ("VTS_01_0.BUP", good)]);
+        let ts = parse_vts(&mut disc, &udf, 1, &[(1, 1), (1, 2)]).expect("BUP used");
+        assert_eq!(ts.titles.len(), 2);
+        let lba = udf
+            .file_start_lba(&mut disc, "/VIDEO_TS/VTS_01_0.IFO")
+            .unwrap();
+        assert_eq!(ts.vob_start_sector, lba + 7);
+    }
+
+    /// An IFO that parses but drops a damaged PGC defers to a BUP that keeps it.
+    #[test]
+    fn parse_vts_prefers_a_bup_that_keeps_more_titles() {
+        let (_, good) = bup_fixture();
+        let mut damaged = good.clone();
+        // Second PGC entry's offset: point it past the end of the table.
+        damaged[2 * 2048 + 8 + 8 + 4..2 * 2048 + 8 + 8 + 8]
+            .copy_from_slice(&0x00ff_ffffu32.to_be_bytes());
+        let (mut disc, udf) = video_ts_disc(vec![
+            ("VTS_01_0.IFO", damaged.clone()),
+            ("VTS_01_0.BUP", good),
+        ]);
+        let ts = parse_vts(&mut disc, &udf, 1, &[(1, 1), (1, 2)]).expect("vts");
+        assert_eq!(ts.titles.len(), 2, "BUP kept both titles");
+        // With no usable BUP the IFO's partial result stands.
+        let (mut disc, udf) = video_ts_disc(vec![("VTS_01_0.IFO", damaged)]);
+        let ts = parse_vts(&mut disc, &udf, 1, &[(1, 1), (1, 2)]).expect("vts");
+        assert_eq!(ts.titles.len(), 1);
+    }
+
+    /// A stop during the BUP attempt is a stop, not a reason to report the IFO's error.
+    #[test]
+    fn parse_vts_propagates_a_halt_during_the_bup_attempt() {
+        struct HaltAt(MemDisc, u32);
+        impl SectorSource for HaltAt {
+            fn read_sectors(&mut self, lba: u32, n: u16, buf: &mut [u8], r: bool) -> Result<usize> {
+                if lba == self.1 {
+                    return Err(Error::Halted);
+                }
+                self.0.read_sectors(lba, n, buf, r)
+            }
+        }
+        let (bad, good) = bup_fixture();
+        let (mut disc, udf) = video_ts_disc(vec![("VTS_01_0.IFO", bad), ("VTS_01_0.BUP", good)]);
+        let bup_lba = udf
+            .file_start_lba(&mut disc, "/VIDEO_TS/VTS_01_0.BUP")
+            .unwrap();
+        let r = parse_vts(&mut HaltAt(disc, bup_lba), &udf, 1, &[(1, 1)]);
+        assert!(matches!(r, Err(Error::Halted)), "{r:?}");
+    }
+
     #[test]
     fn parse_vts_rejects_bad_magic_and_short_files() {
         let mut bad_magic = build_vts_ifo(0, 0, &one_pgc(), None);

From 9cb0ad73d3cbd7240f4efd9fd4f57aaa140f4715 Mon Sep 17 00:00:00 2001
From: Matthew Jackson <1085847+MattJackson@users.noreply.github.com>
Date: Thu, 1 Oct 2026 14:50:27 -0700
Subject: [PATCH 8/8] mpls: warn on dropped play items and STN entries;
 spec_guards, lint_stop tests

---
 src/mpls.rs          | 28 +++++++++++++++++++++++++---
 tests/lint_stop.rs   | 28 +++++++++++++++++++---------
 tests/spec_guards.rs | 20 ++++++++++++++++++++
 3 files changed, 64 insertions(+), 12 deletions(-)

diff --git a/src/mpls.rs b/src/mpls.rs
index 1165e5bc..ea7eb80a 100644
--- a/src/mpls.rs
+++ b/src/mpls.rs
@@ -30,8 +30,8 @@ pub(crate) struct PlaylistMark {
     /// Chapter filters should test `== 1`, not `<= 1`.
     pub mark_type: u8,
     /// Which play item this mark belongs to. Carries the per-PlayItem
-    /// timebase needed to place a mark in a multi-PlayItem playlist;
-    /// the chapter builder does not consume it yet.
+    /// timebase needed to place a mark in a multi-PlayItem playlist; the
+    /// chapter builder resolves each mark against that PlayItem.
     pub play_item_ref: u16,
     /// Timestamp in 45kHz PTS ticks
     pub timestamp: u32,
@@ -141,6 +141,12 @@ pub fn parse(data: &[u8]) -> Result<Playlist> {
 
         let item = &pl[pos + 2..pos + 2 + item_length];
         if item.len() < 20 {
+            tracing::warn!(
+                target: "freemkv::mpls",
+                item_idx,
+                item_length,
+                "play item too short to read; it is dropped from the playlist"
+            );
             pos += 2 + item_length;
             continue;
         }
@@ -184,6 +190,7 @@ pub fn parse(data: &[u8]) -> Result<Playlist> {
                     streams.push(entry);
                     spos = next;
                 } else {
+                    stn_entry_unreadable("primary video");
                     break;
                 }
             }
@@ -193,6 +200,7 @@ pub fn parse(data: &[u8]) -> Result<Playlist> {
                     streams.push(entry);
                     spos = next;
                 } else {
+                    stn_entry_unreadable("primary audio");
                     break;
                 }
             }
@@ -206,6 +214,7 @@ pub fn parse(data: &[u8]) -> Result<Playlist> {
                     streams.push(entry);
                     spos = next;
                 } else {
+                    stn_entry_unreadable("PG subtitle");
                     break;
                 }
             }
@@ -214,6 +223,7 @@ pub fn parse(data: &[u8]) -> Result<Playlist> {
                 if let Some((_, next)) = parse_stream_entry(item, spos, STREAM_CATEGORY_IG) {
                     spos = next;
                 } else {
+                    stn_entry_unreadable("IG");
                     break;
                 }
             }
@@ -233,6 +243,7 @@ pub fn parse(data: &[u8]) -> Result<Playlist> {
                         spos = next;
                     }
                 } else {
+                    stn_entry_unreadable("secondary audio");
                     break;
                 }
             }
@@ -260,6 +271,7 @@ pub fn parse(data: &[u8]) -> Result<Playlist> {
                         spos = next;
                     }
                 } else {
+                    stn_entry_unreadable("secondary video");
                     break;
                 }
             }
@@ -273,6 +285,7 @@ pub fn parse(data: &[u8]) -> Result<Playlist> {
                     streams.push(entry);
                     spos = next;
                 } else {
+                    stn_entry_unreadable("Dolby Vision enhancement layer");
                     break;
                 }
             }
@@ -336,6 +349,15 @@ pub fn parse(data: &[u8]) -> Result<Playlist> {
     })
 }
 
+// An unreadable stream entry ends its STN category and every one after it.
+fn stn_entry_unreadable(kind: &str) {
+    tracing::warn!(
+        target: "freemkv::mpls",
+        kind,
+        "unreadable STN stream entry; this and the later stream entries are dropped"
+    );
+}
+
 impl Playlist {
     /// Total play-item running time in 45 kHz ticks (out_time - in_time, summed).
     pub fn duration_ticks(&self) -> u64 {
@@ -380,7 +402,7 @@ fn parse_stream_entry(item: &[u8], pos: usize, stream_type: u8) -> Option<(Strea
 
     // PID location depends on stream-entry type (BD spec stream_entry()): type 1
     // (PlayItem's Clip) → +2; type 2 (SubPath SubClip) → +4; type 3/4 (SubPath
-    // clip / DV enhancement layer) → +3. Previously only type 1 was handled.
+    // clip / DV enhancement layer) → +3.
     let pid_off = match item[pos + 1] {
         STREAM_ENTRY_PLAYITEM_CLIP => 2,
         STREAM_ENTRY_SUBPATH_SUBCLIP => 4,
diff --git a/tests/lint_stop.rs b/tests/lint_stop.rs
index a6bae9a3..1deaa4ff 100644
--- a/tests/lint_stop.rs
+++ b/tests/lint_stop.rs
@@ -398,19 +398,29 @@ fn no_thread_sleep_on_op_paths() {
     let mut hits = Vec::new();
     for s in srcs.iter().filter(|s| in_dirs(s, OP_DIRS)) {
         hits.extend(s.hits("thread::sleep").into_iter().map(|i| (s, i)));
-        for i in s.hits("thread::{") {
-            let group = &s.code[i..close_of(s.code.as_bytes(), i + 8)];
-            if group
-                .split(|c: char| !is_ident(c as u8))
-                .any(|w| w == "sleep")
-            {
-                hits.push((s, i));
-            }
-        }
+        hits.extend(sleep_imports(&s.code).into_iter().map(|i| (s, i)));
     }
     check("thread::sleep on an op path", hits, ALLOW);
 }
 
+// Offsets of `thread::{...}` import groups that bring `sleep` into scope.
+fn sleep_imports(code: &str) -> Vec<usize> {
+    code.match_indices("thread::{")
+        .map(|(i, _)| i)
+        .filter(|&i| {
+            code[i..close_of(code.as_bytes(), i + 8)]
+                .split(|c: char| !is_ident(c as u8))
+                .any(|w| w == "sleep")
+        })
+        .collect()
+}
+
+#[test]
+fn sleep_imports_finds_a_grouped_sleep_only() {
+    let code = "use std::thread::{self, sleep};\nuse std::thread::{self, spawn};\nuse a::thread::{sleeper};";
+    assert_eq!(sleep_imports(code), vec![code.find("thread::{").unwrap()]);
+}
+
 /// §2.2: "**Every** raw `self.scsi.as_mut().execute` in `drive/mod.rs` and `identity.rs`
 /// goes through [`Drive::exec`]"; §5.8 widens the grep to all of `drive/`.
 #[test]
diff --git a/tests/spec_guards.rs b/tests/spec_guards.rs
index a878c663..b425d488 100644
--- a/tests/spec_guards.rs
+++ b/tests/spec_guards.rs
@@ -264,6 +264,26 @@ fn v20_stride_64_evidence() {
     );
 }
 
+/// KS-27: HD DVD `.evo` units carry the flag in PES_scrambling_control (bits 5-4 of byte
+/// 20). Literal offsets here, so a drifted constant in the library fails this guard.
+#[test]
+fn hddvd_flag_is_bits_5_4_of_byte_20() {
+    let unit_with = |at: usize, b: u8| {
+        let mut u = vec![0u8; ALIGNED_UNIT_LEN];
+        u[at] = b;
+        aacs_unit_encrypted(&u, ContentFormat::MpegPs)
+    };
+    for b in [0x10, 0x20, 0x30, 0xFF] {
+        assert!(unit_with(20, b), "byte 20 = {b:#04x}");
+    }
+    for b in [0x00, 0x0F, 0x40, 0x80, 0xC0] {
+        assert!(!unit_with(20, b), "byte 20 = {b:#04x}");
+    }
+    for at in [0, 19, 21] {
+        assert!(!unit_with(at, 0x30), "byte {at}");
+    }
+}
+
 /// per evidence (no public spec); do not change without evidence proving otherwise —
 /// KS-27: the HD DVD book was "removed from this AACS website due to inactivity".
 #[test]