diff --git a/crates/engine/src/clip_group_file.rs b/crates/engine/src/clip_group_file.rs
index 607d5b5..e20caf0 100644
--- a/crates/engine/src/clip_group_file.rs
+++ b/crates/engine/src/clip_group_file.rs
@@ -14,7 +14,7 @@ use std::path::{Path, PathBuf};
 
 pub const EXTENSION: &str = "scgrp";
 const FORMAT: &str = "soundcraft.clipgroup";
-/// Refuse files that would place absurd numbers of clips.
+/// Refuse files that would place absurd numbers of clips, tracks or audio files.
 const MAX_CLIPS: usize = 10_000;
 
 #[derive(Debug, Serialize, Deserialize)]
@@ -89,30 +89,45 @@ pub fn import(e: &mut Engine, path: &str, first: Option<TrackId>, at: Samples) -
     if file.format != FORMAT {
         return Err(EngineError::BadParams(id.into(), "not a SoundCraft clip group file".into()));
     }
-    if file.lanes.iter().map(Vec::len).sum::<usize>() > MAX_CLIPS {
+    if file.lanes.iter().map(|l| l.len().max(1)).sum::<usize>() > MAX_CLIPS || file.audio.len() > MAX_CLIPS {
         return Err(EngineError::BadParams(id.into(), "clip group file has too many clips".into()));
     }
     let dir = Path::new(path).parent().map(Path::to_path_buf).unwrap_or_default();
-    // Decode audio first so a bad file changes nothing.
-    let mut decoded = BTreeMap::new();
+    // Decode audio first so a bad file changes nothing, and each file once however many ids name it.
+    let (mut decoded, mut index, mut file_of) = (Vec::new(), BTreeMap::new(), BTreeMap::new());
+    let rate = e.session().sample_rate.hz();
     for (old, rel) in &file.audio {
         let full = dir.join(rel);
         if !full.starts_with(&dir) || rel.contains("..") {
             return Err(EngineError::BadParams(id.into(), format!("audio path escapes the group folder: {rel}")));
         }
-        let bytes = crate::io::read_file(&full)?;
-        let (_, buf) = soundcraft_audio_io::decode(&bytes, Some("wav")).map_err(|err| EngineError::Io(format!("{rel}: {err}")))?;
-        decoded.insert(*old, (rel.clone(), buf));
+        let key = crate::io::file_key(&full);
+        let n = match index.get(&key) {
+            Some(n) => *n,
+            None => {
+                let bytes = crate::io::read_file(&full)?;
+                let (_, buf) = soundcraft_audio_io::decode(&bytes, Some("wav")).map_err(|err| EngineError::Io(format!("{rel}: {err}")))?;
+                let buf = crate::io::at_rate(buf, rate, crate::io::MAX_IMPORT_SAMPLES)
+                    .ok_or_else(|| EngineError::Io(format!("{rel}: too large to import")))?;
+                decoded.push((rel.clone(), buf));
+                index.insert(key, decoded.len() - 1);
+                decoded.len() - 1
+            }
+        };
+        file_of.insert(*old, n);
     }
     let src_rate = f64::from(file.sample_rate.max(1));
     let s = e.session_mut();
     let ratio = f64::from(s.sample_rate.hz()) / src_rate;
     let scale = |v: Samples| -> Samples { (v as f64 * ratio).round() as Samples };
-    let mut map: BTreeMap<u64, SourceId> = BTreeMap::new();
-    for (old, (rel, buf)) in decoded {
-        let name = Path::new(&rel).file_name().and_then(|x| x.to_str()).unwrap_or("clip group").to_string();
-        map.insert(old, crate::io::add_source(s, &name, buf, None, FileFormat::Wav));
-    }
+    let sources: Vec<SourceId> = decoded
+        .into_iter()
+        .map(|(rel, buf)| {
+            let name = Path::new(&rel).file_name().and_then(|x| x.to_str()).unwrap_or("clip group").to_string();
+            crate::io::add_source(s, &name, buf, None, FileFormat::Wav)
+        })
+        .collect();
+    let map: BTreeMap<u64, SourceId> = file_of.into_iter().filter_map(|(old, n)| Some((old, *sources.get(n)?))).collect();
     let start_idx = first.and_then(|t| s.tracks.iter().position(|x| x.id == t));
     let mut placed = Vec::new();
     let group_id = s.alloc();
@@ -144,9 +159,9 @@ pub fn import(e: &mut Engine, path: &str, first: Option<TrackId>, at: Samples) -
             }
             c.id = s.new_clip_id();
             c.start = at.saturating_add(scale(c.start.max(0)));
-            c.length = scale(c.length).max(1);
+            c.length = scale(c.length);
             c.group = Some(group_id);
-            c.clamp_fades();
+            c.sanitize();
             placed.push(c.id);
             crate::edit::place_clip(s, target, c);
         }
@@ -192,6 +207,46 @@ mod tests {
         let _ = std::fs::remove_dir_all(&dir);
     }
 
+    #[test]
+    fn positions_in_a_group_file_are_kept_within_reach() {
+        let dir = std::env::temp_dir().join(format!("sc-grp-far-{}", std::process::id()));
+        let _ = std::fs::create_dir_all(&dir);
+        let p = dir.join("far.scgrp");
+        let note = json!({"pitch": 60, "velocity": 100, "release_velocity": 64, "channel": 0, "start": i64::MAX, "length": i64::MAX});
+        let clip =
+            json!({"id": 1, "name": "far", "start": i64::MAX, "length": i64::MAX, "content": {"Midi": {"sequence": {"notes": [note], "ctrls": []}}}});
+        let file = json!({"format": "soundcraft.clipgroup", "version": 1, "sample_rate": 48000, "length": 1, "lanes": [[clip]], "audio": {}});
+        std::fs::write(&p, file.to_string()).unwrap();
+        let mut e = crate::demo::demo_engine();
+        let r = e.execute("file.import_clip_groups", &json!({"path": p.to_string_lossy()})).unwrap();
+        let id = soundcraft_model::ClipId(r["clips"][0].as_u64().unwrap());
+        let c = e.session().find_clip(id).unwrap().1;
+        assert!(c.start <= crate::cmd::MAX_POSITION && c.length <= crate::cmd::MAX_POSITION);
+        e.execute("edit.select_all", &json!({})).unwrap();
+        for cmd in ["edit.duplicate", "event.extract_chords"] {
+            assert!(!matches!(e.execute(cmd, &json!({})), Err(crate::EngineError::Internal(..))), "{cmd}");
+        }
+        let _ = std::fs::remove_dir_all(&dir);
+    }
+
+    #[test]
+    fn a_file_named_by_many_ids_becomes_one_source() {
+        let dir = std::env::temp_dir().join(format!("sc-grp-shared-{}", std::process::id()));
+        let _ = std::fs::create_dir_all(&dir);
+        let audio = soundcraft_audio_io::AudioBuffer { sample_rate: 48_000, channels: vec![vec![0.25; 480]] };
+        std::fs::write(dir.join("k.wav"), soundcraft_audio_io::encode(&audio, &soundcraft_audio_io::EncodeOptions::default()).unwrap()).unwrap();
+        let clip = |id: u64| json!({"id": id, "name": "k", "start": id * 1000, "length": 480, "content": {"Audio": {"source": id, "offset": 0}}});
+        let audio_paths = json!({"1": "k.wav", "2": "./k.wav", "3": "k.wav"});
+        let file = json!({"format": "soundcraft.clipgroup", "version": 1, "sample_rate": 48000, "length": 4000, "lanes": [[clip(1), clip(2), clip(3)]], "audio": audio_paths});
+        let p = dir.join("k.scgrp");
+        std::fs::write(&p, file.to_string()).unwrap();
+        let mut e = crate::demo::demo_engine();
+        let before = e.session().sources.len();
+        let r = e.execute("file.import_clip_groups", &json!({"path": p.to_string_lossy()})).unwrap();
+        assert_eq!((r["clips"].as_array().unwrap().len(), e.session().sources.len()), (3, before + 1));
+        let _ = std::fs::remove_dir_all(&dir);
+    }
+
     #[test]
     fn rejects_foreign_files_and_escaping_paths() {
         let dir = std::env::temp_dir().join(format!("sc-grp-bad-{}", std::process::id()));
diff --git a/crates/engine/src/cmd/event_more.rs b/crates/engine/src/cmd/event_more.rs
index 3dc634c..c0780a5 100644
--- a/crates/engine/src/cmd/event_more.rs
+++ b/crates/engine/src/cmd/event_more.rs
@@ -555,6 +555,10 @@ pub fn chord_name(weights: &[f64; 12], bass: usize) -> Option<String> {
     Some(name)
 }
 
+/// The most bars Extract Chords looks at (55 hours of 4/4 at 120 BPM), and notes sounding in them.
+const MAX_CHORD_BARS: usize = 100_000;
+const MAX_CHORD_NOTES: usize = 10_000_000;
+
 fn extract_chords(e: &mut Engine, p: &Value) -> Result<Value> {
     let id = "event.extract_chords";
     let (_, t0, t1) = selection_ticks(e, p, id)?;
@@ -580,20 +584,36 @@ fn extract_chords(e: &mut Engine, p: &Value) -> Result<Value> {
             }
         }
     }
-    let first_bar = s.tempo.bar_beat_at_tick(t0).bar;
-    let mut bar = first_bar;
+    notes.sort_unstable_by_key(|n| n.0);
+    let mut bar = s.tempo.bar_beat_at_tick(t0).bar;
+    let mut sounding: Vec<(i64, i64, u8)> = Vec::new();
+    let (mut next, mut bars, mut heard) = (0, 0, 0);
     let mut chords: Vec<Value> = Vec::new();
     let mut marks: Vec<(Samples, String)> = Vec::new();
     let mut last = String::new();
-    while chords.len() < 2000 {
+    while chords.len() < 2000 && bars < MAX_CHORD_BARS && heard < MAX_CHORD_NOTES {
         let a = s.tempo.bar_start_tick(bar).max(t0);
         let b = s.tempo.bar_start_tick(bar + 1).min(t1);
         if a >= t1 {
             break;
         }
+        while let Some(&n) = notes.get(next).filter(|n| n.0 < b) {
+            sounding.push(n);
+            next += 1;
+        }
+        sounding.retain(|n| n.1 > a);
+        if sounding.is_empty() {
+            match notes.get(next) {
+                Some(n) => bar = (bar + 1).max(s.tempo.bar_beat_at_tick(n.0).bar),
+                None => break,
+            }
+            continue;
+        }
+        bars += 1;
+        heard += sounding.len();
         let mut w = [0.0f64; 12];
         let mut bass: Option<u8> = None;
-        for (na, nb, pitch) in &notes {
+        for (na, nb, pitch) in &sounding {
             let ov = (*nb).min(b) - (*na).max(a);
             if ov > 0 {
                 if let Some(x) = w.get_mut(usize::from(*pitch) % 12) {
@@ -901,6 +921,18 @@ mod tests {
         assert!(e.session().markers.iter().any(|m| m.ruler == 2));
     }
 
+    #[test]
+    fn chords_far_down_the_timeline_are_found_without_walking_every_bar() {
+        let mut e = crate::demo::demo_engine();
+        let keys = e.session().track_by_name("Keys").unwrap().id;
+        let far = 1i64 << 39;
+        if let Some(p) = e.session_mut().track_mut(keys).and_then(soundcraft_model::Track::playlist_mut) {
+            p.clips.iter_mut().for_each(|c| c.start += far);
+        }
+        let r = e.execute("event.extract_chords", &json!({"tracks": [keys.0], "start": 0, "end": far + 48_000 * 600})).unwrap();
+        assert!(!r["chords"].as_array().unwrap().is_empty(), "{r}");
+    }
+
     #[test]
     fn beat_detective_finds_demo_tempo() {
         let mut e = crate::demo::demo_engine();
diff --git a/crates/engine/src/cmd/mod.rs b/crates/engine/src/cmd/mod.rs
index 82c178a..cec7628 100644
--- a/crates/engine/src/cmd/mod.rs
+++ b/crates/engine/src/cmd/mod.rs
@@ -244,9 +244,7 @@ pub fn tracks_required(e: &Engine, cmd: &str, p: &Value) -> Result<Vec<TrackId>>
     if t.is_empty() { Err(bad(cmd, "no tracks: pass `track`/`tracks` or select tracks")) } else { Ok(t) }
 }
 
-/// Largest position accepted from parameters: 2^40 samples (about 265 days at 48 kHz). Clamping
-/// here keeps every later addition and subtraction on positions far away from overflow.
-pub const MAX_POSITION: Samples = 1 << 40;
+pub use soundcraft_time::MAX_POSITION;
 
 /// Position from `key`: a number of samples, or `{"seconds": x}`, or a string in the main counter format.
 /// Values are clamped to ±[`MAX_POSITION`].
diff --git a/crates/engine/src/cmd/sampler.rs b/crates/engine/src/cmd/sampler.rs
index 7bac7e8..e467234 100644
--- a/crates/engine/src/cmd/sampler.rs
+++ b/crates/engine/src/cmd/sampler.rs
@@ -62,9 +62,8 @@ fn load(e: &mut Engine, p: &Value) -> Result<Value> {
     if buf.frames() == 0 || buf.num_channels() == 0 {
         return Err(EngineError::Io(format!("{name}: no audio")));
     }
-    if buf.frames().saturating_mul(buf.num_channels()) > MAX_SAMPLE_VALUES {
-        return Err(EngineError::Io(format!("{name}: too long for a sample (ten minutes of 192 kHz stereo at most)")));
-    }
+    let buf = crate::io::at_rate(buf, e.session().sample_rate.hz(), MAX_SAMPLE_VALUES)
+        .ok_or_else(|| EngineError::Io(format!("{name}: too long for a sample (ten minutes of 192 kHz stereo at most)")))?;
     let channels = buf.num_channels();
     let s = e.session_mut();
     let src = crate::io::add_source(s, &name, buf, Some(&path), format.format);
diff --git a/crates/engine/src/cmd/setup_more.rs b/crates/engine/src/cmd/setup_more.rs
index 8dd1640..3d43675 100644
--- a/crates/engine/src/cmd/setup_more.rs
+++ b/crates/engine/src/cmd/setup_more.rs
@@ -5,10 +5,9 @@ use super::more_util::{set_text, store_value, text, toggle_flag, values_with_pre
 use super::*;
 use crate::cmd;
 use serde_json::json;
-use soundcraft_model::{BusId, ChannelFormat, ClipContent, OutputPath, Route, Session, Source, SourceAudio, SourceId, TrackId, TrackKind};
+use soundcraft_model::{BusId, ChannelFormat, ClipContent, OutputPath, Route, Session, SourceId, TrackId, TrackKind};
 use soundcraft_time::Timecode;
 use std::path::{Path, PathBuf};
-use std::sync::Arc;
 
 macro_rules! option {
     ($id:literal, $label:literal, $flag:literal) => {
@@ -403,18 +402,6 @@ fn midi_inputs(e: &mut Engine, p: &Value) -> Result<Value> {
     Ok(json!({"enabled": enabled}))
 }
 
-/// Decode a source file of another session (paths relative to that session's folder).
-fn load_source(dir: &Path, src: &Source, sr: u32) -> Option<soundcraft_audio_io::AudioBuffer> {
-    let p = if Path::new(&src.path).is_absolute() { PathBuf::from(&src.path) } else { dir.join(&src.path) };
-    let bytes = crate::io::read_file(&p).ok()?;
-    let (_, mut buf) = soundcraft_audio_io::decode(&bytes, p.extension().and_then(|x| x.to_str())).ok()?;
-    if buf.sample_rate != sr && buf.sample_rate > 0 {
-        buf.channels = soundcraft_dsp::offline::resample(&buf.channels, buf.sample_rate, sr);
-        buf.sample_rate = sr;
-    }
-    Some(buf)
-}
-
 fn import_session_data(e: &mut Engine, p: &Value) -> Result<Value> {
     let id = "file.import_session_data";
     let path = str_param(p, "path").filter(|x| !x.trim().is_empty()).ok_or_else(|| bad(id, "`path` required"))?.to_string();
@@ -443,31 +430,29 @@ fn import_session_data(e: &mut Engine, p: &Value) -> Result<Value> {
     needed.sort_by_key(|x| x.0);
     needed.dedup();
     let sr = e.session().sample_rate.hz();
-    let decoded: Vec<(Source, Option<soundcraft_audio_io::AudioBuffer>)> =
-        needed.iter().filter_map(|sid| other.source(*sid).cloned()).map(|src| (src.clone(), load_source(&dir, &src, sr))).collect();
     let s = e.session_mut();
+    let mut files = crate::io::DecodedFiles::new();
     let mut map: std::collections::BTreeMap<u64, SourceId> = Default::default();
     let mut missing = Vec::new();
-    for (src, buf) in decoded {
-        let nid = SourceId(s.alloc());
+    for src in needed.iter().filter_map(|sid| other.source(*sid)) {
         let abs = if Path::new(&src.path).is_absolute() { PathBuf::from(&src.path) } else { dir.join(&src.path) };
         let mut ns = src.clone();
-        ns.id = nid;
+        ns.id = SourceId(s.alloc());
         ns.path = abs.to_string_lossy().into_owned();
-        match buf {
-            Some(b) => {
-                ns.frames = b.frames() as u64;
+        match crate::io::decode_file(&mut files, &abs, sr) {
+            Ok(audio) => {
+                ns.frames = audio.buffer.frames() as u64;
                 ns.sample_rate = sr;
                 ns.unsaved = true;
-                s.pool.insert(nid, Arc::new(SourceAudio::new(b)));
+                s.pool.insert(ns.id, audio);
             }
-            None => {
+            Err(_) => {
                 ns.unsaved = false;
                 missing.push(ns.path.clone());
             }
         }
+        map.insert(src.id.0, ns.id);
         s.sources.push(ns);
-        map.insert(src.id.0, nid);
     }
     let mut out = Vec::new();
     for mut tr in picked {
diff --git a/crates/engine/src/io.rs b/crates/engine/src/io.rs
index f0cbf87..fa3d1f8 100644
--- a/crates/engine/src/io.rs
+++ b/crates/engine/src/io.rs
@@ -9,7 +9,21 @@ use std::path::{Path, PathBuf};
 use std::sync::Arc;
 
 /// Largest import we accept (samples per channel × channels), ~4 GiB of f32.
-const MAX_IMPORT_SAMPLES: usize = 1 << 30;
+pub(crate) const MAX_IMPORT_SAMPLES: usize = 1 << 30;
+
+/// `buf` converted to `rate`, unless it would then hold more than `limit` samples: a file with a
+/// tiny sample rate grows by orders of magnitude.
+pub(crate) fn at_rate(mut buf: AudioBuffer, rate: u32, limit: usize) -> Option<AudioBuffer> {
+    let from = buf.sample_rate.max(1);
+    if buf.frames() as f64 * buf.num_channels() as f64 * f64::from(rate) / f64::from(from) > limit as f64 {
+        return None;
+    }
+    if from != rate {
+        buf.channels = soundcraft_dsp::offline::resample(&buf.channels, from, rate);
+        buf.sample_rate = rate;
+    }
+    Some(buf)
+}
 
 // ─── Checked file access ──────────────────────────────────────────────────────────────────────
 //
@@ -20,18 +34,23 @@ const MAX_IMPORT_SAMPLES: usize = 1 << 30;
 // enters it (import, open, sampler load), so playback and bounce read nothing from disk and
 // need no check of their own.
 
-/// The bytes of the file at `path`, which must be inside the automation read root when there is one.
+/// The bytes of the file at `path`, which must be inside the automation read root when there is
+/// one. Only a regular file qualifies: a device or a pipe named by a session or a command would
+/// never end or never answer. Errors name the file.
 pub fn read_file(path: impl AsRef<Path>) -> Result<Vec<u8>> {
     let path = path.as_ref();
     crate::file_access::check_read(path).map_err(EngineError::Io)?;
-    std::fs::read(path).map_err(|err| EngineError::Io(format!("{}: {err}", path.display())))
+    let err = |err: std::io::Error| EngineError::Io(format!("{}: {err}", path.display()));
+    if !std::fs::metadata(path).map_err(err)?.is_file() {
+        return Err(EngineError::Io(format!("{}: not a regular file", path.display())));
+    }
+    std::fs::read(path).map_err(err)
 }
 
-/// [`read_file`] for a text file.
+/// [`read_file`] as UTF-8 text.
 pub fn read_text(path: impl AsRef<Path>) -> Result<String> {
     let path = path.as_ref();
-    crate::file_access::check_read(path).map_err(EngineError::Io)?;
-    std::fs::read_to_string(path).map_err(|err| EngineError::Io(format!("{}: {err}", path.display())))
+    String::from_utf8(read_file(path)?).map_err(|err| EngineError::Io(format!("{}: {err}", path.display())))
 }
 
 /// Is there a file at `path` the automation read root lets us see? A path outside the root is
@@ -58,16 +77,22 @@ pub(crate) fn write_path(path: impl AsRef<Path>, bytes: impl AsRef<[u8]>) -> Res
 /// A relative `Audio Files/` path no other source in `s` already uses.
 fn unique_audio_rel(s: &Session, stem: &str) -> String {
     let stem = sanitize_name(stem);
-    let mut path = format!("Audio Files/{stem}.wav");
-    let mut n = 2u32;
-    while s.sources.iter().any(|src| src.path == path) {
-        path = format!("Audio Files/{stem}-{n}.wav");
-        n = n.saturating_add(1);
-        if n > 10_000 {
-            break;
-        }
+    let (plain, prefix) = (format!("Audio Files/{stem}.wav"), format!("Audio Files/{stem}-"));
+    let used: std::collections::HashSet<u64> = s
+        .sources
+        .iter()
+        .filter_map(|src| {
+            if src.path == plain {
+                return Some(1);
+            }
+            let n = src.path.strip_prefix(&prefix)?.strip_suffix(".wav")?;
+            n.parse().ok().filter(|i: &u64| *i > 1 && i.to_string() == n)
+        })
+        .collect();
+    match (1..).find(|i| !used.contains(i)) {
+        Some(n) if n > 1 => format!("{prefix}{n}.wav"),
+        _ => plain,
     }
-    path
 }
 
 /// Register decoded audio as a new source. Resamples to the session rate if needed.
@@ -111,9 +136,8 @@ fn stamp_at_rate(stamp: u64, file_rate: u32, session_rate: u32) -> u64 {
 pub fn import_audio_bytes(e: &mut Engine, name: &str, bytes: &[u8], path: Option<&str>, target: Option<TrackId>, at: Samples) -> Result<Value> {
     let ext = Path::new(name).extension().and_then(|x| x.to_str()).map(str::to_ascii_lowercase);
     let (info, buf) = soundcraft_audio_io::decode(bytes, ext.as_deref()).map_err(|err| EngineError::Io(format!("{name}: {err}")))?;
-    if buf.frames().saturating_mul(buf.num_channels().max(1)) > MAX_IMPORT_SAMPLES {
-        return Err(EngineError::Io(format!("{name}: file is too large to import")));
-    }
+    let buf = at_rate(buf, e.session().sample_rate.hz(), MAX_IMPORT_SAMPLES)
+        .ok_or_else(|| EngineError::Io(format!("{name}: file is too large to import")))?;
     if buf.frames() == 0 {
         return Err(EngineError::Io(format!("{name}: no audio")));
     }
@@ -222,11 +246,18 @@ pub fn relink_videos(s: &mut Session, session_dir: &Path) -> Vec<String> {
     missing
 }
 
+/// Most meter changes a MIDI file may bring into the tempo map; scores have a handful.
+const MAX_MIDI_METERS: usize = 10_000;
+
 /// Import a Standard MIDI File as MIDI tracks (one per SMF track).
 pub fn import_midi_bytes(e: &mut Engine, bytes: &[u8], at: Samples, tempo_map: bool) -> Result<Vec<TrackId>> {
     let smf = soundcraft_midi::read_smf(bytes).map_err(|err| EngineError::Io(err.to_string()))?;
     let s = e.session_mut();
     if tempo_map {
+        // Each meter is placed by walking the ones before it.
+        if smf.meters.len() > MAX_MIDI_METERS {
+            return Err(EngineError::Io(format!("MIDI file: more than {MAX_MIDI_METERS} meter changes")));
+        }
         for (tick, bpm) in &smf.tempos {
             let _ = s.tempo.set_tempo(*tick, *bpm);
         }
@@ -240,14 +271,18 @@ pub fn import_midi_bytes(e: &mut Engine, bytes: &[u8], at: Samples, tempo_map: b
         if tr.sequence.notes.is_empty() {
             continue;
         }
-        let name = if tr.name.trim().is_empty() { format!("MIDI {}", i + 1) } else { tr.name.clone() };
+        let mut name = if tr.name.trim().is_empty() { format!("MIDI {}", i + 1) } else { tr.name.clone() };
+        soundcraft_model::truncate_chars(&mut name, soundcraft_model::MAX_NAME_CHARS);
         let id = s.add_track(TrackKind::Instrument, ChannelFormat::Stereo, Some(&name));
         let drums = tr.sequence.notes.iter().all(|n| n.channel == 9);
         if let Some(t) = s.track_mut(id) {
             t.instrument = Some(soundcraft_model::Insert::new(if drums { "drum_synth" } else { "subtractive_synth" }));
         }
-        let end_tick = base_tick + tr.sequence.end_tick().max(1);
-        let len = s.tempo.tick_to_samples(end_tick, s.sample_rate) - at;
+        let end_tick = base_tick.saturating_add(tr.sequence.end_tick().max(1));
+        let len = s.tempo.tick_to_samples(end_tick, s.sample_rate).saturating_sub(at);
+        if len > s.sample_rate.samples(86_400.0) {
+            return Err(EngineError::Io(format!("MIDI track {}: longer than 24 hours", i + 1)));
+        }
         let cid = s.new_clip_id();
         crate::edit::place_clip(s, id, Clip::midi(cid, name, at, len.max(1), tr.sequence.clone()));
         out.push(id);
@@ -850,6 +885,7 @@ pub fn save_session_copy(e: &Engine, path: &str) -> Result<usize> {
 /// Write `session` to `path`; returns the session with updated media paths, the number of audio
 /// files written and the final path.
 fn write_session(session: &Session, path: &str, overwrite: bool) -> Result<(Session, usize, PathBuf)> {
+    use std::collections::{HashMap, HashSet};
     let p = session_file(path);
     // Before any audio is written: a session saved outside the write root changes nothing.
     crate::file_access::check_write(&p).map_err(EngineError::Io)?;
@@ -859,8 +895,16 @@ fn write_session(session: &Session, path: &str, overwrite: bool) -> Result<(Sess
     let from = s.folder.clone();
     let same_dir = from.as_deref().is_some_and(|f| same_path(f, &dir));
     let mut written = 0;
-    let shared_paths: Vec<bool> =
-        s.sources.iter().enumerate().map(|(i, src)| s.sources.iter().enumerate().any(|(j, other)| j != i && other.path == src.path)).collect();
+    // A file can stay put for all the sources that name it, unless their audio differs.
+    let shared_paths: Vec<bool> = {
+        let mut audio_by_path: HashMap<&str, HashSet<Option<*const SourceAudio>>> = HashMap::new();
+        for src in &s.sources {
+            audio_by_path.entry(&src.path).or_default().insert(s.pool.get(src.id).map(Arc::as_ptr));
+        }
+        s.sources.iter().map(|src| audio_by_path.get(src.path.as_str()).is_some_and(|a| a.len() > 1)).collect()
+    };
+    // Files written for audio during this save: sources playing the same audio share one.
+    let mut files: HashMap<*const SourceAudio, String> = HashMap::new();
     for (i, src) in s.sources.iter_mut().enumerate() {
         if !same_dir
             && s.pool.get(src.id).is_none()
@@ -880,6 +924,12 @@ fn write_session(session: &Session, path: &str, overwrite: bool) -> Result<(Sess
             continue;
         }
         let Some(audio) = s.pool.get(src.id) else { continue };
+        if let Some(path) = files.get(&Arc::as_ptr(audio)) {
+            src.path.clone_from(path);
+            src.unsaved = false;
+            src.format = FileFormat::Wav;
+            continue;
+        }
         make_dir(&audio_dir)?;
         let mut stem = sanitize_name(&src.name);
         if overwrite {
@@ -888,6 +938,7 @@ fn write_session(session: &Session, path: &str, overwrite: bool) -> Result<(Sess
             if audio_dir.join(format!("{stem}.wav")).exists() {
                 src.path = format!("Audio Files/{stem}.wav");
                 src.unsaved = false;
+                files.insert(Arc::as_ptr(audio), src.path.clone());
                 continue;
             }
         }
@@ -897,6 +948,7 @@ fn write_session(session: &Session, path: &str, overwrite: bool) -> Result<(Sess
         src.path = format!("Audio Files/{name}");
         src.unsaved = false;
         src.format = FileFormat::Wav;
+        files.insert(Arc::as_ptr(audio), src.path.clone());
         written += usize::from(new);
     }
     if written > 0 {
@@ -910,7 +962,7 @@ fn write_session(session: &Session, path: &str, overwrite: bool) -> Result<(Sess
     make_dir(&dir)?;
     // Atomic-ish write: temp file then rename.
     let tmp = p.with_extension("scraft.tmp");
-    if !overwrite && std::fs::read(&p).is_ok_and(|old| old != text.as_bytes()) {
+    if !overwrite && read_file(&p).is_ok_and(|old| old != text.as_bytes()) {
         back_up(&p);
     }
     replace_file(&tmp, &p, text.as_bytes())?;
@@ -1038,20 +1090,12 @@ pub fn open_session(e: &mut Engine, path: &str) -> Result<Vec<String>> {
     let mut s = Session::from_json(&text).map_err(|err| EngineError::Io(err.to_string()))?;
     let dir = Path::new(path).parent().map(Path::to_path_buf).unwrap_or_default();
     let mut missing = Vec::new();
-    for src in s.sources.clone() {
+    let mut files = DecodedFiles::new();
+    for src in &s.sources {
         let p = if Path::new(&src.path).is_absolute() { PathBuf::from(&src.path) } else { dir.join(&src.path) };
-        // A session file is hostile input too: a path in it that leaves the read root is not read.
-        if let Err(why) = crate::file_access::check_read(&p) {
-            missing.push(why);
-            continue;
-        }
-        match std::fs::read(&p) {
-            Ok(bytes) => {
-                if let Err(err) = load_source_audio(&mut s, src.id, &bytes, p.extension().and_then(|x| x.to_str())) {
-                    missing.push(format!("{}: {err}", p.display()));
-                }
-            }
-            Err(_) => missing.push(p.display().to_string()),
+        match decode_file(&mut files, &p, s.sample_rate.hz()) {
+            Ok(audio) => s.pool.insert(src.id, audio),
+            Err(err) => missing.push(err),
         }
     }
     missing.extend(relink_videos(&mut s, &dir));
@@ -1064,15 +1108,33 @@ pub fn open_session(e: &mut Engine, path: &str) -> Result<Vec<String>> {
     Ok(missing)
 }
 
-/// Decode one source's audio file into the session pool, at the session rate.
-fn load_source_audio(s: &mut Session, id: SourceId, bytes: &[u8], ext: Option<&str>) -> std::result::Result<(), String> {
-    let (_, mut buf) = soundcraft_audio_io::decode(bytes, ext).map_err(|err| err.to_string())?;
-    if buf.sample_rate != s.sample_rate.hz() && buf.sample_rate > 0 {
-        buf.channels = soundcraft_dsp::offline::resample(&buf.channels, buf.sample_rate, s.sample_rate.hz());
-        buf.sample_rate = s.sample_rate.hz();
-    }
-    s.pool.insert(id, Arc::new(SourceAudio::new(buf)));
-    Ok(())
+/// Decode one source's audio file at the session rate.
+fn decode_source(bytes: &[u8], ext: Option<&str>, rate: u32) -> std::result::Result<Arc<SourceAudio>, String> {
+    let (_, buf) = soundcraft_audio_io::decode(bytes, ext).map_err(|err| err.to_string())?;
+    let buf = at_rate(buf, rate, MAX_IMPORT_SAMPLES).ok_or("too large to load")?;
+    Ok(Arc::new(SourceAudio::new(buf)))
+}
+
+/// Audio files decoded so far, by path: a session may name one file thousands of times.
+/// The one name of the file at `p` (links followed), so the same file named two ways is read once.
+pub(crate) fn file_key(p: &Path) -> PathBuf {
+    std::fs::canonicalize(p).unwrap_or_else(|_| p.to_path_buf())
+}
+
+pub(crate) type DecodedFiles = std::collections::HashMap<PathBuf, std::result::Result<Arc<SourceAudio>, String>>;
+
+/// The audio of the file at `p` at `rate`, decoded the first time it is asked for. The error
+/// names the file.
+/// A file named in a session is hostile input too: a path that leaves the read root is not read.
+pub(crate) fn decode_file(files: &mut DecodedFiles, p: &Path, rate: u32) -> std::result::Result<Arc<SourceAudio>, String> {
+    crate::file_access::check_read(p)?;
+    files
+        .entry(file_key(p))
+        .or_insert_with(|| {
+            let bytes = read_file(p).map_err(|_| p.display().to_string())?;
+            decode_source(&bytes, p.extension().and_then(|x| x.to_str()), rate).map_err(|err| format!("{}: {err}", p.display()))
+        })
+        .clone()
 }
 
 // ─── Hosts without a filesystem (the browser) ─────────────────────────────────────────────────
@@ -1176,14 +1238,12 @@ pub fn open_session_bytes(e: &mut Engine, name: &str, bytes: &[u8]) -> Result<Ve
     };
     let mut s = Session::from_json(&text).map_err(|err| EngineError::Io(format!("{name}: {err}")))?;
     let mut missing = Vec::new();
-    for src in s.sources.clone() {
+    for src in &s.sources {
         match files.remove(&src.path) {
-            Some(audio) => {
-                let ext = Path::new(&src.path).extension().and_then(|x| x.to_str()).map(str::to_string);
-                if let Err(err) = load_source_audio(&mut s, src.id, &audio, ext.as_deref()) {
-                    missing.push(format!("{}: {err}", src.path));
-                }
-            }
+            Some(audio) => match decode_source(&audio, Path::new(&src.path).extension().and_then(|x| x.to_str()), s.sample_rate.hz()) {
+                Ok(audio) => s.pool.insert(src.id, audio),
+                Err(err) => missing.push(format!("{}: {err}", src.path)),
+            },
             None => missing.push(src.path.clone()),
         }
     }
@@ -1295,8 +1355,9 @@ pub fn add_recording(e: &mut Engine, start: Samples, takes: Vec<(TrackId, PathBu
     let before = e.session_arc();
     let mut out = Vec::new();
     for (tid, path) in takes {
-        let read = std::fs::read(&path).map_err(|x| x.to_string()).and_then(|b| soundcraft_audio_io::decode(&b, None).map_err(|x| x.to_string()));
-        let Ok((_, buf)) = read.inspect_err(|err| e.message(format!("{}: {err}", path.display()))) else { continue };
+        let read =
+            read_file(&path).and_then(|b| soundcraft_audio_io::decode(&b, None).map_err(|err| EngineError::Io(format!("{}: {err}", path.display()))));
+        let Ok((_, buf)) = read.inspect_err(|err| e.message(err.to_string())) else { continue };
         let s = e.session_mut();
         if s.track(tid).is_none() {
             continue;
@@ -1600,6 +1661,145 @@ mod save_tests {
     }
 }
 
+#[cfg(test)]
+mod rate_tests {
+    use super::*;
+
+    #[test]
+    fn a_tiny_sample_rate_is_refused_before_it_is_converted() {
+        let buf = |rate| AudioBuffer { sample_rate: rate, channels: vec![vec![0.5; 100]; 2] };
+        assert!(at_rate(buf(1), 48_000, 1_000_000).is_none());
+        let ok = at_rate(buf(8_000), 48_000, 1_000_000).unwrap();
+        assert_eq!((ok.sample_rate, ok.frames()), (48_000, 600));
+    }
+}
+
+#[cfg(test)]
+mod open_tests {
+    use super::*;
+
+    #[test]
+    fn a_file_named_by_many_sources_is_decoded_once() {
+        let dir = std::env::temp_dir().join(format!("soundcraft-shared-{}", std::process::id()));
+        let _ = std::fs::remove_dir_all(&dir);
+        std::fs::create_dir_all(&dir).unwrap();
+        let audio = AudioBuffer { sample_rate: 48_000, channels: vec![vec![0.25; 480]] };
+        std::fs::write(dir.join("k.wav"), soundcraft_audio_io::encode(&audio, &EncodeOptions::default()).unwrap()).unwrap();
+        let mut s = Session::default();
+        for _ in 0..3 {
+            add_source(&mut s, "k", audio.clone(), Some("k.wav"), FileFormat::Wav);
+        }
+        let path = dir.join("Song.scraft").to_string_lossy().into_owned();
+        std::fs::write(&path, s.to_json().unwrap()).unwrap();
+        let mut e = Engine::default();
+        assert!(open_session(&mut e, &path).unwrap().is_empty());
+        let (sources, pool) = (&e.session().sources, &e.session().pool);
+        let first = pool.get(sources[0].id).unwrap();
+        assert!(sources.iter().all(|src| pool.get(src.id).is_some_and(|a| Arc::ptr_eq(a, first))));
+        let _ = std::fs::remove_dir_all(&dir);
+    }
+
+    #[test]
+    fn sources_playing_one_file_share_it_when_saved() {
+        let dir = std::env::temp_dir().join(format!("soundcraft-shared-save-{}", std::process::id()));
+        let _ = std::fs::remove_dir_all(&dir);
+        std::fs::create_dir_all(dir.join("Audio Files")).unwrap();
+        let audio = AudioBuffer { sample_rate: 48_000, channels: vec![vec![0.25; 480]] };
+        std::fs::write(dir.join("Audio Files/k.wav"), soundcraft_audio_io::encode(&audio, &EncodeOptions::default()).unwrap()).unwrap();
+        let mut s = Session::default();
+        for _ in 0..3 {
+            add_source(&mut s, "k", audio.clone(), Some("Audio Files/k.wav"), FileFormat::Wav);
+        }
+        s.sources.iter_mut().for_each(|src| src.unsaved = false);
+        let path = dir.join("Song.scraft").to_string_lossy().into_owned();
+        std::fs::write(&path, s.to_json().unwrap()).unwrap();
+        let mut e = Engine::default();
+        open_session(&mut e, &path).unwrap();
+        assert_eq!(save_session(&mut e, &path).unwrap(), 0);
+        assert!(e.session().sources.iter().all(|src| src.path == "Audio Files/k.wav"));
+        assert_eq!(save_copy(&e, &dir.join("copy/Song.scraft").to_string_lossy()).unwrap(), 1);
+        assert_eq!(std::fs::read_dir(dir.join("copy/Audio Files")).unwrap().count(), 1);
+        let _ = std::fs::remove_dir_all(&dir);
+    }
+}
+
+#[cfg(test)]
+mod name_tests {
+    use super::*;
+
+    #[test]
+    fn a_midi_track_name_is_cut_to_a_length_that_can_be_drawn() {
+        let note = soundcraft_midi::Note { pitch: 60, velocity: 100, release_velocity: 64, channel: 0, start: 0, length: 960 };
+        let sequence = soundcraft_midi::Sequence { notes: vec![note], ..Default::default() };
+        let smf = soundcraft_midi::Smf { tracks: vec![soundcraft_midi::SmfTrack { name: "n".repeat(1_000_000), sequence }], ..Default::default() };
+        let mut e = Engine::default();
+        let ids = import_midi_bytes(&mut e, &soundcraft_midi::write_smf(&smf).unwrap(), 0, false).unwrap();
+        let track = e.session().track(ids[0]).unwrap();
+        assert_eq!((track.name.len(), track.clips()[0].name.len()), (soundcraft_model::MAX_NAME_CHARS, soundcraft_model::MAX_NAME_CHARS));
+    }
+
+    #[test]
+    fn midi_longer_than_a_day_is_refused() {
+        let held = soundcraft_midi::Note { pitch: 60, velocity: 100, release_velocity: 64, channel: 0, start: 0, length: (1 << 28) - 1 };
+        let sequence = soundcraft_midi::Sequence { notes: vec![held], ..Default::default() };
+        let smf = soundcraft_midi::Smf { tracks: vec![soundcraft_midi::SmfTrack { name: String::new(), sequence }], ..Default::default() };
+        let err = import_midi_bytes(&mut Engine::default(), &soundcraft_midi::write_smf(&smf).unwrap(), 0, false).unwrap_err();
+        assert!(err.to_string().contains("longer than 24 hours"), "{err}");
+    }
+
+    #[test]
+    fn midi_with_more_meter_changes_than_scores_have_is_refused() {
+        let note = soundcraft_midi::Note { pitch: 60, velocity: 100, release_velocity: 64, channel: 0, start: 0, length: 960 };
+        let sequence = soundcraft_midi::Sequence { notes: vec![note], ..Default::default() };
+        let meters = (0..=MAX_MIDI_METERS as i64).map(|bar| (bar * 3840, 4, 4)).collect();
+        let smf = soundcraft_midi::Smf { tracks: vec![soundcraft_midi::SmfTrack { name: String::new(), sequence }], meters, ..Default::default() };
+        let err = import_midi_bytes(&mut Engine::default(), &soundcraft_midi::write_smf(&smf).unwrap(), 0, true).unwrap_err();
+        assert!(err.to_string().contains("meter changes"), "{err}");
+    }
+
+    #[test]
+    fn new_sources_take_the_first_free_file_name() {
+        let mut s = Session::default();
+        let buf = || AudioBuffer { sample_rate: 48_000, channels: vec![vec![0.0; 4]] };
+        add_source(&mut s, "k", buf(), Some("Audio Files/k-02.wav"), FileFormat::Wav);
+        let mut path = || {
+            let id = add_source(&mut s, "k", buf(), None, FileFormat::Wav);
+            s.source(id).map(|x| x.path.clone()).unwrap_or_default()
+        };
+        assert_eq!([path(), path(), path()], ["Audio Files/k.wav", "Audio Files/k-2.wav", "Audio Files/k-3.wav"]);
+    }
+}
+
+#[cfg(all(test, unix))]
+mod pipe_tests {
+    use super::*;
+
+    #[test]
+    fn a_pipe_named_as_media_is_refused_not_waited_on() {
+        let dir = std::env::temp_dir().join(format!("soundcraft-pipe-{}", std::process::id()));
+        let _ = std::fs::remove_dir_all(&dir);
+        std::fs::create_dir_all(&dir).unwrap();
+        let fifo = dir.join("pipe.wav");
+        assert!(std::process::Command::new("mkfifo").arg(&fifo).status().unwrap().success());
+        let mut s = Session::default();
+        let audio = AudioBuffer { sample_rate: 48_000, channels: vec![vec![0.0; 10]] };
+        add_source(&mut s, "pipe", audio, Some(&fifo.to_string_lossy()), FileFormat::Wav);
+        let path = dir.join("Song.scraft").to_string_lossy().into_owned();
+        std::fs::write(&path, s.to_json().unwrap()).unwrap();
+        let (tx, rx) = std::sync::mpsc::channel();
+        let pipe = fifo.to_string_lossy().into_owned();
+        std::thread::spawn(move || {
+            let mut e = Engine::default();
+            let imported = e.execute("file.import_audio", &json!({"path": pipe})).is_ok();
+            let _ = tx.send((imported, open_session(&mut e, &path).map_err(|err| err.to_string())));
+        });
+        let (imported, opened) = rx.recv_timeout(std::time::Duration::from_secs(10)).unwrap();
+        assert!(!imported);
+        assert_eq!(opened.unwrap(), [fifo.display().to_string()]);
+        let _ = std::fs::remove_dir_all(&dir);
+    }
+}
+
 #[cfg(test)]
 mod stem_tests {
     #[test]
diff --git a/crates/engine/tests/hostile_sessions.rs b/crates/engine/tests/hostile_sessions.rs
index 5a98b02..06b785e 100644
--- a/crates/engine/tests/hostile_sessions.rs
+++ b/crates/engine/tests/hostile_sessions.rs
@@ -26,6 +26,43 @@ fn demo_json() -> Value {
     serde_json::to_value(e.session()).unwrap()
 }
 
+#[test]
+fn positions_at_the_ends_of_the_range_do_not_overflow_commands() {
+    let (max, min) = (serde_json::json!(i64::MAX), serde_json::json!(i64::MIN));
+    let kick = "/tracks/0/playlists/0/clips/0";
+    let cases = [
+        (format!("{kick}/start"), &max, "edit.duplicate"),
+        (format!("{kick}/start"), &max, "edit.insert_silence"),
+        (format!("{kick}/length"), &max, "edit.heal"),
+        (format!("{kick}/length"), &max, "edit.trim_to_file_boundaries"),
+        (format!("{kick}/content/Audio/offset"), &min, "edit.trim_to_file_boundaries"),
+        (format!("{kick}/sync_point"), &max, "clip.quantize_to_grid"),
+        (format!("{kick}/gain_env"), &serde_json::json!([[i64::MIN, 0.0]]), "edit.separate_on_grid"),
+        ("/tracks/4/automation/0/points/0/at".into(), &min, "automation.thin_all"),
+        ("/tracks/5/playlists/0/clips/0/content/Midi/sequence/notes/0/start".into(), &max, "event.extract_chords"),
+        ("/markers/0/start".into(), &max, "event.insert_time"),
+        ("/markers/1/end".into(), &min, "edit.copy"),
+        ("/edit/selection/start".into(), &min, "edit.move_selection_left"),
+    ];
+    let (demo, base) = (soundcraft_engine::demo::demo_engine(), demo_json());
+    let failed: Vec<String> = cases
+        .into_iter()
+        .filter_map(|(path, value, cmd)| {
+            let mut v = base.clone();
+            *v.pointer_mut(&path).unwrap() = value.clone();
+            let mut s = soundcraft_model::Session::from_json(&v.to_string()).unwrap();
+            s.pool = demo.session().pool.clone();
+            let mut e = soundcraft_engine::Engine::new(s);
+            if !path.starts_with("/edit") {
+                e.execute("edit.select_all", &serde_json::json!({})).unwrap();
+            }
+            let r = e.execute(cmd, &serde_json::json!({}));
+            matches!(r, Err(soundcraft_engine::EngineError::Internal(..))).then(|| format!("{path} = {value}, {cmd}: {r:?}"))
+        })
+        .collect();
+    assert!(failed.is_empty(), "{failed:#?}");
+}
+
 proptest! {
     #![proptest_config(ProptestConfig { cases: 96, .. ProptestConfig::default() })]
     #[test]
diff --git a/crates/model/src/clip.rs b/crates/model/src/clip.rs
index 52fef5c..c18470a 100644
--- a/crates/model/src/clip.rs
+++ b/crates/model/src/clip.rs
@@ -1,8 +1,8 @@
 //! Clips: windows onto audio sources or MIDI sequences, placed on a playlist.
 
-use crate::{ClipId, SourceId};
+use crate::{ClipId, MAX_NAME_CHARS, SourceId, truncate_chars};
 use soundcraft_midi::Sequence;
-use soundcraft_time::{Range, Samples};
+use soundcraft_time::{MAX_POSITION, Range, Samples};
 
 /// Fade curve shapes (Pro Tools offers standard, equal-power, S-curve and custom presets).
 #[derive(Debug, Clone, Copy, PartialEq, Eq, Hash, Default, serde::Serialize, serde::Deserialize)]
@@ -252,6 +252,39 @@ impl Clip {
             self.sync_point = 0;
         }
     }
+
+    /// Repair a clip read from a file: positions and lengths within ±[`MAX_POSITION`], as commands
+    /// keep theirs, fades within the clip, a name that can be drawn, and a usable gain and stretch.
+    pub fn sanitize(&mut self) {
+        bound(&mut self.start);
+        self.length = self.length.clamp(1, MAX_POSITION);
+        bound(&mut self.sync_point);
+        self.gain_env.iter_mut().for_each(|(at, _)| bound(at));
+        match &mut self.content {
+            ClipContent::Audio { offset, .. } | ClipContent::Video { offset, .. } => bound(offset),
+            ClipContent::Midi { sequence } => bound_sequence(sequence),
+        }
+        self.clamp_fades();
+        truncate_chars(&mut self.name, MAX_NAME_CHARS);
+        if !self.gain_db.is_finite() {
+            self.gain_db = 0.0;
+        }
+        if !self.stretch.is_finite() || self.stretch <= 0.0 {
+            self.stretch = 1.0;
+        }
+    }
+}
+
+pub(crate) fn bound(at: &mut Samples) {
+    *at = (*at).clamp(-MAX_POSITION, MAX_POSITION);
+}
+
+pub(crate) fn bound_sequence(s: &mut Sequence) {
+    for n in &mut s.notes {
+        bound(&mut n.start);
+        n.length = n.length.clamp(1, MAX_POSITION);
+    }
+    s.ctrls.iter_mut().for_each(|c| bound(&mut c.tick));
 }
 
 fn env_value(env: &[(Samples, f32)], at: Samples) -> f32 {
diff --git a/crates/model/src/lib.rs b/crates/model/src/lib.rs
index 138c7e8..61596b7 100644
--- a/crates/model/src/lib.rs
+++ b/crates/model/src/lib.rs
@@ -23,7 +23,8 @@ pub use mixer::{
     Bus, ChannelFormat, INSERT_SLOTS, Insert, Mixer, OutputPath, Route, SEND_SLOTS, SendSlot, Speaker, SurroundPan, fader_db_to_pos, fader_pos_to_db,
 };
 pub use session::{
-    BitDepthSetting, EditMode, EditState, FEET_FRAMES_START, SESSION_EXTENSION, Session, SessionError, Tool, TrackView, ZoomState, ZoomToggle,
+    BitDepthSetting, EditMode, EditState, FEET_FRAMES_START, MAX_COMMENT_CHARS, MAX_NAME_CHARS, SESSION_EXTENSION, Session, SessionError, Tool,
+    TrackView, ZoomState, ZoomToggle, truncate_chars,
 };
 pub use source::{Source, SourceAudio, SourcePool, VideoSource};
 pub use track::{Playlist, TRACK_COLORS, Track, TrackHeight, TrackKind};
diff --git a/crates/model/src/session.rs b/crates/model/src/session.rs
index 84c6480..449d82d 100644
--- a/crates/model/src/session.rs
+++ b/crates/model/src/session.rs
@@ -1,5 +1,6 @@
 //! The session: the whole document.
 
+use crate::clip::{bound, bound_sequence};
 use crate::{
     Bus, BusId, ChannelFormat, Clip, ClipId, Group, GroupId, MarkerId, MarkerKind, MemoryLocation, OutputPath, Source, SourceId, SourcePool,
     TRACK_COLORS, Track, TrackId, TrackKind, VideoSource,
@@ -461,14 +462,15 @@ impl Session {
         if !base.is_empty() && !taken(base) && !matches!(base, "Audio" | "Aux" | "MIDI" | "Inst" | "VCA" | "Folder" | "Master") {
             return base.to_string();
         }
-        let mut i = 1;
-        loop {
-            let cand = format!("{base} {i}");
-            if !taken(&cand) {
-                return cand;
-            }
-            i += 1;
-        }
+        let prefix = format!("{base} ");
+        let used: std::collections::HashSet<u64> = self
+            .tracks
+            .iter()
+            .filter_map(|t| t.name.strip_prefix(&prefix))
+            .filter_map(|n| n.parse().ok().filter(|i: &u64| i.to_string() == n))
+            .collect();
+        let i = (1..).find(|i| !used.contains(i)).unwrap_or(1);
+        format!("{base} {i}")
     }
 
     /// Add a track with defaults; returns its id.
@@ -557,8 +559,12 @@ impl Session {
             .max()
             .unwrap_or(0);
         self.next_id = self.next_id.max(max_id.saturating_add(1));
+        truncate_chars(&mut self.name, MAX_NAME_CHARS);
+        truncate_chars(&mut self.comments, MAX_COMMENT_CHARS);
         for t in &mut self.tracks {
             t.mixer.sanitize();
+            truncate_chars(&mut t.name, MAX_NAME_CHARS);
+            truncate_chars(&mut t.comments, MAX_COMMENT_CHARS);
             if t.playlists.is_empty() {
                 t.playlists.push(crate::Playlist::new(t.name.clone()));
             }
@@ -566,24 +572,42 @@ impl Session {
                 t.active_playlist = 0;
             }
             for p in &mut t.playlists {
+                truncate_chars(&mut p.name, MAX_NAME_CHARS);
                 p.clips.retain(|c| c.length > 0);
-                for c in &mut p.clips {
-                    c.fade_in.len = c.fade_in.len.clamp(0, c.length);
-                    c.fade_out.len = c.fade_out.len.clamp(0, c.length);
-                    if !c.gain_db.is_finite() {
-                        c.gain_db = 0.0;
-                    }
-                    if !c.stretch.is_finite() || c.stretch <= 0.0 {
-                        c.stretch = 1.0;
-                    }
-                }
+                p.clips.iter_mut().for_each(Clip::sanitize);
                 p.sort();
             }
             for l in &mut t.automation {
                 l.points.retain(|p| p.value.is_finite());
+                l.points.iter_mut().for_each(|p| bound(&mut p.at));
                 l.points.sort_by_key(|p| p.at);
             }
         }
+        for m in &mut self.markers {
+            bound(&mut m.start);
+            bound(&mut m.end);
+            truncate_chars(&mut m.name, MAX_NAME_CHARS);
+            truncate_chars(&mut m.comments, MAX_COMMENT_CHARS);
+        }
+        for (at, key) in &mut self.key_signatures {
+            bound(at);
+            truncate_chars(key, MAX_NAME_CHARS);
+        }
+        self.midi_originals.values_mut().for_each(bound_sequence);
+        let e = &mut self.edit;
+        for at in [
+            &mut e.selection.start,
+            &mut e.selection.end,
+            &mut e.timeline_selection.start,
+            &mut e.timeline_selection.end,
+            &mut e.playhead,
+            &mut e.pre_roll,
+            &mut e.post_roll,
+            &mut e.zoom.scroll,
+            &mut self.timecode_start,
+        ] {
+            bound(at);
+        }
         for v in &mut self.videos {
             if !v.frame_rate.is_finite() || v.frame_rate < 0.0 {
                 v.frame_rate = 0.0;
@@ -591,7 +615,12 @@ impl Session {
             if !v.duration.is_finite() || v.duration < 0.0 {
                 v.duration = 0.0;
             }
+            truncate_chars(&mut v.name, MAX_NAME_CHARS);
         }
+        self.busses.iter_mut().for_each(|b| truncate_chars(&mut b.name, MAX_NAME_CHARS));
+        self.outputs.iter_mut().for_each(|o| truncate_chars(&mut o.name, MAX_NAME_CHARS));
+        self.groups.iter_mut().for_each(|g| truncate_chars(&mut g.name, MAX_NAME_CHARS));
+        self.sources.iter_mut().for_each(|s| truncate_chars(&mut s.name, MAX_NAME_CHARS));
         // Drop performances whose clip no longer exists anywhere (any playlist).
         let clip_ids: std::collections::BTreeSet<u64> =
             self.tracks.iter().flat_map(|t| t.playlists.iter().flat_map(|p| p.clips.iter().map(|c| c.id.0))).collect();
@@ -599,6 +628,23 @@ impl Session {
         if !self.edit.zoom.samples_per_px.is_finite() || self.edit.zoom.samples_per_px <= 0.0 {
             self.edit.zoom.samples_per_px = 1024.0;
         }
+        if SampleRate::new(self.sample_rate.hz()).is_err() {
+            self.sample_rate = SampleRate::default();
+        }
+        self.tempo.sanitize();
+    }
+}
+
+/// The most characters kept of a name read from a file: longer ones can't be shown, and drawing
+/// a name of a million characters overflows the renderer's buffers.
+pub const MAX_NAME_CHARS: usize = 256;
+/// The most characters kept of a comment read from a file.
+pub const MAX_COMMENT_CHARS: usize = 4096;
+
+/// Cut `s` to at most `max` characters.
+pub fn truncate_chars(s: &mut String, max: usize) {
+    if let Some((end, _)) = s.char_indices().nth(max) {
+        s.truncate(end);
     }
 }
 
@@ -670,6 +716,39 @@ mod tests {
         assert_eq!(c.source_offset(), 580);
     }
 
+    #[test]
+    fn unique_track_names_take_the_first_free_number() {
+        let mut s = Session::default();
+        for name in ["Piano", "Piano 1", "Piano 3", "Piano 02", "Pianos 2"] {
+            s.add_track(TrackKind::Audio, ChannelFormat::Mono, Some(name));
+        }
+        assert_eq!(s.unique_track_name("Piano"), "Piano 2");
+        assert_eq!(s.unique_track_name("Organ"), "Organ");
+        assert_eq!(s.unique_track_name("Audio"), "Audio 1");
+    }
+
+    #[test]
+    fn names_from_a_file_are_cut_to_a_length_that_can_be_drawn() {
+        let mut s = Session::default();
+        let t = s.add_track(TrackKind::Audio, ChannelFormat::Mono, None);
+        if let Some(tr) = s.track_mut(t) {
+            tr.name = "é".repeat(1_000);
+        }
+        s.comments = "c".repeat(10_000);
+        let back = Session::from_json(&s.to_json().unwrap()).unwrap();
+        assert_eq!(back.track(t).map(|tr| tr.name.chars().count()), Some(MAX_NAME_CHARS));
+        assert_eq!(back.comments.len(), MAX_COMMENT_CHARS);
+    }
+
+    #[test]
+    fn a_bad_sample_rate_or_tempo_is_repaired_on_load() {
+        let mut v = serde_json::to_value(Session::default()).unwrap();
+        v["sample_rate"] = serde_json::json!(0);
+        v["tempo"]["tempos"] = serde_json::json!([{"tick": 0, "bpm": 4e9}]);
+        let s = Session::from_json(&v.to_string()).unwrap();
+        assert_eq!((s.sample_rate, s.tempo), (SampleRate::HZ_48000, TempoMap::default()));
+    }
+
     #[test]
     fn rejects_garbage_and_future_versions() {
         assert!(Session::from_json("not json").is_err());
diff --git a/crates/time/src/lib.rs b/crates/time/src/lib.rs
index 4b68934..7e9d4b9 100644
--- a/crates/time/src/lib.rs
+++ b/crates/time/src/lib.rs
@@ -19,6 +19,10 @@ pub use timecode::{FrameRate, Timecode};
 /// A position or length in samples.
 pub type Samples = i64;
 
+/// Largest position accepted from parameters and files: 2^40 samples (about 265 days at 48 kHz).
+/// Clamping there keeps every later addition and subtraction on positions far away from overflow.
+pub const MAX_POSITION: Samples = 1 << 40;
+
 /// Errors from parsing or converting time values.
 #[derive(Debug, Clone, PartialEq, thiserror::Error)]
 pub enum TimeError {
diff --git a/crates/time/src/tempo.rs b/crates/time/src/tempo.rs
index c4f0482..6d16471 100644
--- a/crates/time/src/tempo.rs
+++ b/crates/time/src/tempo.rs
@@ -55,6 +55,10 @@ fn valid_bpm(bpm: f64) -> Result<f64, TimeError> {
     if bpm.is_finite() && (5.0..=1000.0).contains(&bpm) { Ok(bpm) } else { Err(TimeError::Tempo(bpm)) }
 }
 
+fn valid_meter(numerator: u32, denominator: u32) -> bool {
+    (1..=64).contains(&numerator) && [1, 2, 4, 8, 16, 32, 64].contains(&denominator)
+}
+
 impl TempoMap {
     pub fn new(bpm: f64, numerator: u32, denominator: u32) -> Result<Self, TimeError> {
         let mut m = TempoMap::default();
@@ -70,6 +74,25 @@ impl TempoMap {
         &self.meters
     }
 
+    /// Repair a map read from a file: only valid tempos and meters, in tick order, with one of each
+    /// at tick 0.
+    pub fn sanitize(&mut self) {
+        self.tempos.retain(|e| e.tick >= 0 && valid_bpm(e.bpm).is_ok());
+        self.tempos.sort_by_key(|e| e.tick);
+        self.tempos.dedup_by_key(|e| e.tick);
+        if self.tempos.first().is_none_or(|e| e.tick > 0) {
+            let bpm = self.tempos.first().map_or(120.0, |e| e.bpm);
+            self.tempos.insert(0, TempoEvent { tick: 0, bpm });
+        }
+        self.meters.retain(|m| m.tick >= 0 && valid_meter(m.numerator, m.denominator));
+        self.meters.sort_by_key(|m| m.tick);
+        self.meters.dedup_by_key(|m| m.tick);
+        if self.meters.first().is_none_or(|m| m.tick > 0) {
+            let (numerator, denominator) = self.meters.first().map_or((4, 4), |m| (m.numerator, m.denominator));
+            self.meters.insert(0, MeterEvent { tick: 0, numerator, denominator });
+        }
+    }
+
     /// Insert or replace the tempo at `tick`.
     pub fn set_tempo(&mut self, tick: i64, bpm: f64) -> Result<(), TimeError> {
         let bpm = valid_bpm(bpm)?;
@@ -98,7 +121,7 @@ impl TempoMap {
     /// Insert or replace the meter at `tick` (snapped to the bar line at or before it).
     /// Later meter changes keep their bar numbers, so they stay on bar lines.
     pub fn set_meter(&mut self, tick: i64, numerator: u32, denominator: u32) -> Result<(), TimeError> {
-        if !(1..=64).contains(&numerator) || ![1, 2, 4, 8, 16, 32, 64].contains(&denominator) {
+        if !valid_meter(numerator, denominator) {
             return Err(TimeError::Meter(numerator, denominator));
         }
         let tick = if tick <= 0 { 0 } else { self.bar_start_tick(self.bar_beat_at_tick(tick).bar) };
@@ -347,6 +370,22 @@ mod tests {
         assert_eq!(m.bar_beat_at_tick(TICKS_PER_QUARTER / 2), BarBeat { bar: 1, beat: 2, tick: 0 });
     }
 
+    #[test]
+    fn sanitize_keeps_what_the_setters_accept() {
+        let tempo = |tick, bpm| TempoEvent { tick, bpm };
+        let meter = |tick, numerator, denominator| MeterEvent { tick, numerator, denominator };
+        let mut m = TempoMap {
+            tempos: vec![tempo(960, 4e9), tempo(3840, 90.0), tempo(-5, 100.0), tempo(1920, 60.0), tempo(1920, 70.0)],
+            meters: vec![meter(0, 0, 4), meter(3840, 3, 4)],
+        };
+        m.sanitize();
+        assert_eq!(m.tempos(), [tempo(0, 60.0), tempo(1920, 60.0), tempo(3840, 90.0)]);
+        assert_eq!(m.meters(), [meter(0, 3, 4), meter(3840, 3, 4)]);
+        let mut empty = TempoMap { tempos: Vec::new(), meters: Vec::new() };
+        empty.sanitize();
+        assert_eq!(empty, TempoMap::default());
+    }
+
     #[test]
     fn rejects_bad_values() {
         let mut m = TempoMap::default();
diff --git a/crates/ui-egui/src/edit_window.rs b/crates/ui-egui/src/edit_window.rs
index fa96d95..c7e615c 100644
--- a/crates/ui-egui/src/edit_window.rs
+++ b/crates/ui-egui/src/edit_window.rs
@@ -180,7 +180,7 @@ fn status_bar(app: &mut SoundApp, ui: &mut Ui) {
     let t = Tokens::current();
     let r = ui.max_rect();
     let s = app.engine.session();
-    let left = format!(
+    let mut left = format!(
         "{} · {} Hz · {} · {} tracks · {}",
         s.name,
         s.sample_rate.hz(),
@@ -192,6 +192,7 @@ fn status_bar(app: &mut SoundApp, ui: &mut Ui) {
         s.tracks.len(),
         app.ui.status
     );
+    soundcraft_model::truncate_chars(&mut left, 4 * soundcraft_model::MAX_NAME_CHARS);
     ui.painter().text(pos2(r.min.x + 10.0, r.center().y), Align2::LEFT_CENTER, left, regular(11.0), t.text_dim);
     let undo = app.engine.undo_label().map_or(String::new(), |l| format!("Undo {l}"));
     ui.painter().text(
@@ -2517,6 +2518,15 @@ mod tests {
         h
     }
 
+    #[test]
+    fn a_file_time_stamp_at_the_end_of_the_range_draws() {
+        let mut engine = soundcraft_engine::demo::demo_engine();
+        let s = engine.session_mut();
+        s.edit.flags.insert("view.clip.time.original".into());
+        s.sources.iter_mut().for_each(|src| src.time_reference = i64::MAX as u64);
+        harness_with(engine).run_steps(2);
+    }
+
     fn smart_demo() -> Harness<'static, SoundApp> {
         let mut engine = soundcraft_engine::demo::demo_engine();
         engine.execute("edit.tool", &json!({"tool": "smart"})).unwrap();