From ed25de6521731c6ef9dc284d127ac467c11e679b Mon Sep 17 00:00:00 2001
From: jyviko <2501648+jyviko@users.noreply.github.com>
Date: Fri, 16 Oct 2026 00:35:32 -0400
Subject: [PATCH] engine: crash reports name the startup step, the renderer and
 a native crash (#299)

The journal keeps the startup step the app is in (phase) and the renderer
(set_environment) across rebases; an unclean exit before the first frame is
reported "during startup (<step>, N s after launch)". native_paths() is where
a native exception filter writes what it caught and a minidump; the next
start puts the exception code, module+offset and thread into the report and
moves the minidump into its folder. Adapted from SolidCraft's crash.rs.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01UhhZMBTviDQxZvwnyP89fo
---
 crates/engine/src/crash.rs       | 205 ++++++++++++++++++++++++++++---
 crates/engine/src/crash_tests.rs | 106 ++++++++++++++++
 2 files changed, 295 insertions(+), 16 deletions(-)

diff --git a/crates/engine/src/crash.rs b/crates/engine/src/crash.rs
index 287b912..933cf48 100644
--- a/crates/engine/src/crash.rs
+++ b/crates/engine/src/crash.rs
@@ -19,8 +19,16 @@
 //!   written again; at most [`MAX_NEW_PER_SESSION`] new reports per run, [`MAX_REPORTS`]
 //!   reports, [`MAX_TOTAL_BYTES`] on disk, nothing older than [`MAX_AGE_DAYS`] days.
 //!
+//! - **Startup steps** ([`phase`]): the journal keeps the step the app is in while it gets its
+//!   window and graphics device up (window, graphics instance, adapter, device, shader
+//!   compiles, first frame, [`RUNNING`]), so a crash inside a graphics driver still says where
+//!   it happened, and the renderer ([`set_environment`]) once the adapter is picked.
+//! - **Native crashes** (Windows): the app's exception filter writes what it caught (exception
+//!   code, faulting module and offset) and a minidump next to the journal ([`native_paths`]);
+//!   the next start puts both into the unclean exit's report.
+//!
 //! Reports are folders `crashes/<time>-<signature>/` holding `report.json`, and when known
-//! `model.fieldcraft`, `replay.json` and `log.txt`. Nothing is ever sent anywhere.
+//! `model.fieldcraft`, `replay.json`, `log.txt` and `minidump.dmp`. Nothing is ever sent anywhere.
 //!
 //! Adapted from SolidCraft's `crates/engine/src/crash.rs` (MIT OR Apache-2.0), see ATTRIBUTION.md.
 
@@ -61,6 +69,8 @@ const LOG_TAIL_BYTES: usize = 64 << 10;
 pub const FORMAT: &str = "fieldcraft-crash/1";
 /// The model file in a report folder.
 pub const MODEL_FILE: &str = "model.fieldcraft";
+/// The minidump of a native crash in a report folder (Windows).
+pub const MINIDUMP_FILE: &str = "minidump.dmp";
 
 /// What the app is (shown in every report).
 #[derive(Clone, Debug, Default)]
@@ -112,8 +122,13 @@ struct State {
     known: Mutex<HashMap<u64, (u64, String)>>,
     written: AtomicUsize,
     started: u64,
+    /// When the app started, in milliseconds (for how far into the start a step came).
+    started_ms: u64,
 }
 
+/// The startup step that ends startup: the app is up and drawing.
+pub const RUNNING: &str = "running";
+
 static STATE: OnceLock<State> = OnceLock::new();
 /// The hook is writing a report (a panic inside it must not write another).
 static IN_HOOK: AtomicBool = AtomicBool::new(false);
@@ -147,6 +162,10 @@ fn now() -> u64 {
     std::time::SystemTime::now().duration_since(std::time::UNIX_EPOCH).map_or(0, |d| d.as_secs())
 }
 
+fn now_ms() -> u64 {
+    std::time::SystemTime::now().duration_since(std::time::UNIX_EPOCH).map_or(0, |d| u64::try_from(d.as_millis()).unwrap_or(u64::MAX))
+}
+
 /// `secs` since 1970 as (year, month, day, hour, minute, second) in UTC.
 fn civil(secs: u64) -> (i64, i64, i64, u64, u64, u64) {
     let days = i64::try_from(secs / 86_400).unwrap_or(0);
@@ -304,10 +323,12 @@ fn frames(bt: &str) -> Vec<String> {
 pub fn install(dir: PathBuf, build: Build) -> Vec<Summary> {
     let _ = fs::create_dir_all(dir.join("sessions"));
     let started = now();
+    let started_ms = now_ms();
     for path in dead_journals(&dir) {
         unclean_exit(&dir, &build, &path);
         remove_journal(&path);
     }
+    remove_stray_native_files(&dir);
     prune(&dir, started);
     // Reports the user has been told about (by id).
     let seen_file = dir.join(".seen");
@@ -320,7 +341,10 @@ pub fn install(dir: PathBuf, build: Build) -> Vec<Summary> {
     let _ = fs::write(&seen_file, all.iter().map(|s| s.id.as_str()).collect::<Vec<_>>().join("\n"));
     let known = all.into_iter().filter_map(|s| sig_of(&s.id).map(|sig| (sig, (0, s.id)))).collect();
     let journal = Journal::open(&dir, &build, started);
-    if STATE.set(State { dir, build, journal: Mutex::new(journal), known: Mutex::new(known), written: AtomicUsize::new(0), started }).is_ok() {
+    if STATE
+        .set(State { dir, build, journal: Mutex::new(journal), known: Mutex::new(known), written: AtomicUsize::new(0), started, started_ms })
+        .is_ok()
+    {
         let previous = std::panic::take_hook();
         std::panic::set_hook(Box::new(move |info| {
             if !hook(info) {
@@ -348,6 +372,59 @@ pub fn activity(what: &str) {
     }
 }
 
+/// The app is about to start a step of getting up (`"window"`, `"device creation"`, …;
+/// [`RUNNING`] once it draws): the journal keeps the latest, so a crash nothing catches (inside a
+/// graphics driver, say) is still reported with the step it happened in.
+pub fn phase(step: &str) {
+    let Some(s) = STATE.get() else { return };
+    if let Ok(mut j) = s.journal.lock() {
+        if j.phase_step.as_deref() == Some(step) {
+            return;
+        }
+        let line = json!({ "phase": limited(step, 200), "ms": now_ms().saturating_sub(s.started_ms) }).to_string();
+        j.write(&line);
+        j.phase = Some(line);
+        j.phase_step = Some(step.to_string());
+    }
+}
+
+/// The renderer, GPU and driver, once known (one short line): reports show it as
+/// `system.environment`.
+pub fn set_environment(text: &str) {
+    let Some(s) = STATE.get() else { return };
+    if let Ok(mut j) = s.journal.lock() {
+        let line = json!({ "environment": limited(text, 500) }).to_string();
+        j.write(&line);
+        j.environment = Some(line);
+    }
+}
+
+/// Where a native crash handler writes what it caught for this run: a small JSON file
+/// (`code`, `name`, `address`, `module`, `offset`, `detail`, `thread`) and a minidump. The next
+/// start reports both with this run's unclean exit. `None` before [`install`] or without a journal.
+pub fn native_paths() -> Option<(PathBuf, PathBuf)> {
+    let s = STATE.get()?;
+    let j = s.journal.lock().ok()?;
+    j.path.as_ref().map(|p| native_paths_for(p))
+}
+
+fn native_paths_for(journal: &Path) -> (PathBuf, PathBuf) {
+    (journal.with_extension("native.json"), journal.with_extension("dmp"))
+}
+
+/// Native crash files whose journal is gone (their report was written, or never will be).
+fn remove_stray_native_files(dir: &Path) {
+    for path in fs::read_dir(dir.join("sessions")).into_iter().flatten().flatten().map(|e| e.path()).take(200) {
+        let name = path.file_name().and_then(|n| n.to_str()).unwrap_or_default();
+        let stem = name.strip_suffix(".native.json").or_else(|| name.strip_suffix(".dmp"));
+        if let Some(stem) = stem
+            && !path.with_file_name(format!("{stem}.jsonl")).exists()
+        {
+            let _ = fs::remove_file(&path);
+        }
+    }
+}
+
 /// The app is closing normally: its journal goes, and repeat counts are written.
 pub fn end_session() {
     let Some(s) = STATE.get() else { return };
@@ -514,6 +591,7 @@ pub(crate) fn command_done(s: &Session, journaled: bool, changed: bool, id: &str
             base: json!(if crashed { "the model as it was when the command started" } else { "the model after the command" }),
             notes: notes.clone(),
             fields: serde_json::Map::new(),
+            attach: Vec::new(),
             log_pid: Some(std::process::id()),
         };
         write_report(state, kind, Some(&p), extra);
@@ -571,6 +649,10 @@ struct Journal {
     /// The latest activity's line and text (kept across rebases).
     activity: Option<String>,
     activity_text: Option<String>,
+    /// The latest startup step's line and name, and the renderer's line (kept across rebases).
+    phase: Option<String>,
+    phase_step: Option<String>,
+    environment: Option<String>,
 }
 
 impl Journal {
@@ -590,6 +672,9 @@ impl Journal {
             running_at: None,
             activity: None,
             activity_text: None,
+            phase: None,
+            phase_step: None,
+            environment: None,
         };
         j.rebase(&json!("new"), 0);
         j.document = None;
@@ -621,7 +706,7 @@ impl Journal {
         let h = self.header.clone();
         self.write(&h);
         self.record(&json!({ "base": base }));
-        if let Some(line) = self.activity.clone() {
+        for line in [self.activity.clone(), self.phase.clone(), self.environment.clone()].into_iter().flatten() {
             self.write(&line);
         }
     }
@@ -680,6 +765,10 @@ struct JournalRead {
     reported: bool,
     /// The latest activity outside commands.
     activity: Option<String>,
+    /// The latest startup step and how many milliseconds after the start it began.
+    phase: Option<(String, u64)>,
+    /// The renderer, once known.
+    environment: Option<String>,
 }
 
 // Read through the lock-owning file object: on Windows an independently opened handle cannot
@@ -713,6 +802,14 @@ fn parse_journal(text: &str) -> JournalRead {
             r.activity = Some(a.to_string());
             continue;
         }
+        if let Some(p) = v.get("phase").and_then(Value::as_str) {
+            r.phase = Some((p.to_string(), v.get("ms").and_then(Value::as_u64).unwrap_or(0)));
+            continue;
+        }
+        if let Some(e) = v.get("environment").and_then(Value::as_str) {
+            r.environment = Some(e.to_string());
+            continue;
+        }
         r.reported = v.get("reported").is_some();
         if let Some(b) = v.get("base") {
             r.base = b.clone();
@@ -766,6 +863,8 @@ fn dead_journals(dir: &Path) -> Vec<PathBuf> {
 
 fn unclean_exit(dir: &Path, build: &Build, journal: &Path) {
     let j = read_journal(journal);
+    let (native_file, dump_file) = native_paths_for(journal);
+    let native = fs::read(&native_file).ok().and_then(|b| serde_json::from_slice::<Value>(&b).ok()).filter(Value::is_object);
     if j.reported {
         return;
     }
@@ -773,17 +872,33 @@ fn unclean_exit(dir: &Path, build: &Build, journal: &Path) {
     let when = j.header.get("start").and_then(Value::as_str).unwrap_or("?").to_string();
     let pid = j.header.get("pid").and_then(Value::as_u64).and_then(|p| u32::try_from(p).ok());
     let doing = j.in_flight.as_ref().and_then(|c| c.get("command")).and_then(Value::as_str).map(str::to_string);
-    let during = match (&doing, &j.activity) {
-        (Some(c), _) => format!("while running `{c}`"),
-        (None, Some(a)) => format!("between commands (last: {a})"),
-        (None, None) => "between commands".to_string(),
+    // A run that never got to drawing died while starting up: say at which step.
+    let starting = j.phase.as_ref().filter(|(p, _)| p != RUNNING).cloned();
+    let during = match (&starting, &doing, &j.activity) {
+        (Some((p, ms)), ..) => format!("during startup ({p}, {:.1} s after launch)", *ms as f64 / 1000.0),
+        (None, Some(c), _) => format!("while running `{c}`"),
+        (None, None, Some(a)) => format!("between commands (last: {a})"),
+        (None, None, None) => "between commands".to_string(),
     };
-    let p = Panic {
-        message: format!("FieldCraft {was} (started {when}) ended without a clean exit {during}"),
-        location: format!("unclean exit in {}", doing.as_deref().unwrap_or("(between commands)")),
-        thread: "(unknown)".into(),
-        backtrace: Vec::new(),
-        signature: signature("unclean exit", doing.as_deref().or(j.activity.as_deref()).unwrap_or("idle")),
+    // What the run was doing, for the signature: the step, the command or the last activity.
+    let what = starting
+        .as_ref()
+        .map(|(p, _)| format!("startup: {p}"))
+        .or_else(|| doing.clone())
+        .or_else(|| j.activity.clone())
+        .unwrap_or_else(|| "idle".into());
+    let p = match &native {
+        Some(n) => native_panic(n, &was, &when, &during, &what),
+        None => Panic {
+            message: format!("FieldCraft {was} (started {when}) ended without a clean exit {during}"),
+            location: match (&starting, &doing) {
+                (Some((p, _)), _) => format!("unclean exit during startup: {p}"),
+                (None, c) => format!("unclean exit in {}", c.as_deref().unwrap_or("(between commands)")),
+            },
+            thread: "(unknown)".into(),
+            backtrace: Vec::new(),
+            signature: signature("unclean exit", &what),
+        },
     };
     // A temporary state just for this report (the app's own is not set up yet).
     let state = State {
@@ -799,10 +914,14 @@ fn unclean_exit(dir: &Path, build: &Build, journal: &Path) {
             running_at: None,
             activity: None,
             activity_text: None,
+            phase: None,
+            phase_step: None,
+            environment: None,
         }),
         known: Mutex::new(list(dir).into_iter().filter_map(|s| sig_of(&s.id).map(|sig| (sig, (0, s.id)))).collect()),
         written: AtomicUsize::new(0),
         started: now(),
+        started_ms: now_ms(),
     };
     if let Ok(mut k) = state.known.lock()
         && let Some(e) = k.get_mut(&p.signature)
@@ -813,7 +932,39 @@ fn unclean_exit(dir: &Path, build: &Build, journal: &Path) {
         bump(dir, &id, n);
         return;
     }
-    write_report(&state, "unclean_exit", Some(&p), from_journal(j, pid));
+    let mut extra = from_journal(j, pid);
+    if let Some(n) = native {
+        extra.fields.insert("native".into(), n);
+        if dump_file.is_file() {
+            extra.attach.push(("minidump".into(), dump_file, MINIDUMP_FILE.into()));
+        }
+    }
+    write_report(&state, "unclean_exit", Some(&p), extra);
+}
+
+/// The report of a crash a native exception filter caught (`native`: what it wrote, untrusted:
+/// every field is cut to length and may be missing).
+fn native_panic(native: &Value, was: &str, when: &str, during: &str, what: &str) -> Panic {
+    let field = |k: &str| native.get(k).and_then(Value::as_str).map(|v| limited(v, 300));
+    let code = field("code").unwrap_or_else(|| "?".into());
+    let name = field("name").unwrap_or_else(|| "exception".into());
+    let module = field("module").unwrap_or_else(|| "(unknown module)".into());
+    let short = module.rsplit(['\\', '/']).next().unwrap_or(&module).to_string();
+    let offset = field("offset").unwrap_or_else(|| "?".into());
+    let at = format!("{short}+{offset}");
+    let mut backtrace = vec![format!("{code} {name}{}", field("detail").map(|d| format!(" ({d})")).unwrap_or_default())];
+    backtrace.push(format!("at {module}+{offset} (address {})", field("address").unwrap_or_else(|| "?".into())));
+    if let Some(t) = native.get("thread").and_then(Value::as_u64) {
+        backtrace.push(format!("on thread {t}"));
+    }
+    Panic {
+        message: format!("FieldCraft {was} (started {when}) crashed with {name} ({code}) in {at} {during}"),
+        location: format!("native exception in {at}"),
+        thread: native.get("thread").and_then(Value::as_u64).map_or_else(|| "(unknown)".into(), |t| format!("native thread {t}")),
+        backtrace,
+        // The place: the module and the offset into it (signature() ignores the digits).
+        signature: signature("native exception", &format!("{code} {short} {what}")),
+    }
 }
 
 // ---------------------------------------------------------------------------------------------
@@ -826,8 +977,10 @@ struct Extra {
     recent: Vec<Value>,
     base: Value,
     notes: Vec<String>,
-    /// More top-level fields for the report (`last_activity`).
+    /// More top-level fields for the report (`last_activity`, `startup_phase`, `native`).
     fields: serde_json::Map<String, Value>,
+    /// Files moved into the report's folder: (key in `files`, source, name in the folder).
+    attach: Vec<(String, PathBuf, String)>,
     /// The process whose log lines go into the report.
     log_pid: Option<u32>,
 }
@@ -874,6 +1027,12 @@ fn from_journal(j: JournalRead, log_pid: Option<u32>) -> Extra {
     if let Some(a) = j.activity {
         fields.insert("last_activity".into(), json!(a));
     }
+    if let Some((p, ms)) = j.phase.filter(|(p, _)| p != RUNNING) {
+        fields.insert("startup_phase".into(), json!({ "step": p, "ms": ms }));
+    }
+    if let Some(e) = j.environment {
+        fields.insert("environment".into(), json!(e));
+    }
     Extra {
         command: j.in_flight,
         model,
@@ -885,6 +1044,7 @@ fn from_journal(j: JournalRead, log_pid: Option<u32>) -> Extra {
         },
         notes,
         fields,
+        attach: Vec::new(),
         log_pid,
     }
 }
@@ -928,6 +1088,12 @@ fn write_report(state: &State, kind: &str, p: Option<&Panic>, extra: Extra) -> O
     {
         files.insert("log".into(), json!("log.txt"));
     }
+    for (key, from, name) in &extra.attach {
+        let to = folder.join(name);
+        if fs::rename(from, &to).is_ok() || fs::copy(from, &to).is_ok() {
+            files.insert(key.clone(), json!(name));
+        }
+    }
     let reproduce = files.contains_key("replay").then(|| format!("fieldcraft-cli crashes replay {id}"));
     let mut report = json!({
         "format": FORMAT,
@@ -953,6 +1119,13 @@ fn write_report(state: &State, kind: &str, p: Option<&Panic>, extra: Extra) -> O
     });
     if let Some(r) = report.as_object_mut() {
         for (k, v) in extra.fields {
+            // The renderer goes with the system it ran on.
+            if k == "environment"
+                && let Some(system) = r.get_mut("system").and_then(Value::as_object_mut)
+            {
+                system.insert(k, v);
+                continue;
+            }
             r.entry(k).or_insert(v);
         }
     }
@@ -1076,7 +1249,7 @@ pub fn read(dir: &Path, id: &str) -> std::result::Result<Value, String> {
     let folder = dir.join(id);
     let mut v = read_report_file(&folder.join("report.json")).ok_or_else(|| format!("no crash report `{id}`"))?;
     v["path"] = json!(folder.to_string_lossy());
-    for (k, f) in [("model_path", MODEL_FILE), ("replay_path", "replay.json"), ("log_path", "log.txt")] {
+    for (k, f) in [("model_path", MODEL_FILE), ("replay_path", "replay.json"), ("log_path", "log.txt"), ("minidump_path", MINIDUMP_FILE)] {
         if folder.join(f).is_file() {
             v[k] = json!(folder.join(f).to_string_lossy());
         }
diff --git a/crates/engine/src/crash_tests.rs b/crates/engine/src/crash_tests.rs
index 62c9af9..698d54b 100644
--- a/crates/engine/src/crash_tests.rs
+++ b/crates/engine/src/crash_tests.rs
@@ -37,6 +37,24 @@ fn child() {
         end_session();
         return;
     }
+    // Dying while starting up, before any command: in a graphics driver, with or without what
+    // a native crash handler caught.
+    if mode == "startup" || mode == "native" {
+        phase("window");
+        phase("adapter request");
+        set_environment("Renderer: Vulkan Test GPU (driver 1.2.3)");
+        phase("device creation");
+        if mode == "native" {
+            let (info, dump) = native_paths().unwrap();
+            fs::write(
+                info,
+                r#"{"code":"0xC0000005","name":"EXCEPTION_ACCESS_VIOLATION","detail":"read of 0x0000000000000010","address":"0x00007FFB12345678","module":"C:\\Windows\\System32\\DriverStore\\igvk64.dll","offset":"0x64EA72","thread":4242}"#,
+            )
+            .unwrap();
+            fs::write(dump, b"MDMP fake").unwrap();
+        }
+        std::process::abort();
+    }
     let mut s = Session { crash_journal: true, ..Default::default() };
     s.execute("mesh.node.add", &node(1)).unwrap();
     s.execute("mesh.node.add", &node(2)).unwrap();
@@ -275,3 +293,91 @@ fn reports_are_pruned_to_the_limits() {
     assert_eq!(clear(&d, None), MAX_REPORTS);
     let _ = fs::remove_dir_all(&d);
 }
+
+#[test]
+fn a_crash_while_starting_up_names_the_step_and_the_renderer() {
+    let d = fresh_dir("startup");
+    let (_, ok) = run_child(&d, "startup");
+    assert!(!ok, "the child aborted");
+    let (_, ok) = run_child(&d, "idle");
+    assert!(ok);
+    let (s, v) = only_report(&d);
+    assert_eq!(s.kind, "unclean_exit");
+    assert!(s.message.contains("during startup (device creation"), "{}", s.message);
+    assert_eq!(v["location"], "unclean exit during startup: device creation");
+    assert_eq!(v["startup_phase"]["step"], "device creation");
+    assert_eq!(v["system"]["environment"], "Renderer: Vulkan Test GPU (driver 1.2.3)", "{v}");
+    let _ = fs::remove_dir_all(&d);
+}
+
+#[test]
+fn a_native_crash_is_reported_with_the_module_the_step_and_the_minidump() {
+    let d = fresh_dir("native");
+    let (_, ok) = run_child(&d, "native");
+    assert!(!ok, "the child aborted");
+    let (_, ok) = run_child(&d, "idle");
+    assert!(ok);
+    let (s, v) = only_report(&d);
+    assert_eq!(s.kind, "unclean_exit");
+    assert!(s.message.contains("EXCEPTION_ACCESS_VIOLATION (0xC0000005) in igvk64.dll+0x64EA72 during startup (device creation"), "{}", s.message);
+    assert_eq!(v["location"], "native exception in igvk64.dll+0x64EA72");
+    assert_eq!(v["native"]["thread"], 4242);
+    let bt: Vec<&str> = v["backtrace"].as_array().unwrap().iter().map(|f| f.as_str().unwrap()).collect();
+    assert_eq!(bt[0], "0xC0000005 EXCEPTION_ACCESS_VIOLATION (read of 0x0000000000000010)");
+    assert!(bt[1].contains("igvk64.dll+0x64EA72"), "{bt:?}");
+    assert_eq!(fs::read(v["minidump_path"].as_str().unwrap()).unwrap(), b"MDMP fake");
+    assert_eq!(v["files"]["minidump"], MINIDUMP_FILE);
+    // Nothing is left behind next to the journals.
+    let left: Vec<_> = fs::read_dir(d.join("sessions")).unwrap().flatten().map(|e| e.file_name()).collect();
+    assert!(left.iter().all(|n| n.to_string_lossy().ends_with(".jsonl")), "{left:?}");
+    // The same crash again is counted, not written again.
+    let _ = run_child(&d, "native");
+    let _ = run_child(&d, "idle");
+    let (s, _) = only_report(&d);
+    assert_eq!(s.count, 2);
+    let _ = fs::remove_dir_all(&d);
+}
+
+#[test]
+fn native_crash_files_without_their_journal_are_removed() {
+    let d = fresh_dir("stray");
+    fs::create_dir_all(d.join("sessions")).unwrap();
+    fs::write(d.join("sessions/20261015-000000-1-0.native.json"), "{}").unwrap();
+    fs::write(d.join("sessions/20261015-000000-1-0.dmp"), "MDMP").unwrap();
+    let (_, ok) = run_child(&d, "idle");
+    assert!(ok);
+    assert!(fs::read_dir(d.join("sessions")).unwrap().next().is_none());
+    assert!(list(&d).is_empty());
+    let _ = fs::remove_dir_all(&d);
+}
+
+#[test]
+fn a_hostile_native_file_still_makes_a_bounded_report() {
+    // Whatever the filter left (cut short, wrong types, huge strings) is data, never trusted.
+    for native in [json!({}), json!({"code": 5, "module": ["x"], "thread": "t"}), json!({"code": "x".repeat(100_000), "module": "y".repeat(100_000)})]
+    {
+        let p = native_panic(&native, "1.0", "then", "between commands", "idle");
+        assert!(p.message.len() < 2_000 && p.backtrace.iter().all(|f| f.len() < 1_000), "{}", p.message.len());
+        assert!(p.location.starts_with("native exception in "));
+    }
+}
+
+#[test]
+fn startup_steps_survive_a_rebase_and_running_ends_startup() {
+    let d = fresh_dir("rebase");
+    fs::create_dir_all(d.join("sessions")).unwrap();
+    let mut j = Journal::open(&d, &build(), now());
+    j.phase = Some(json!({"phase": "first frame", "ms": 5}).to_string());
+    j.environment = Some(json!({"environment": "Renderer: X"}).to_string());
+    j.rebase(&json!("new"), 1);
+    // Read through the journal's own handle, as `read_live_journal` does (Windows).
+    let r = read_journal_file(j.file.as_ref().unwrap().try_clone().unwrap());
+    assert_eq!(r.phase, Some(("first frame".to_string(), 5)));
+    assert_eq!(r.environment.as_deref(), Some("Renderer: X"));
+    j.write(&json!({"phase": RUNNING, "ms": 9}).to_string());
+    let r = read_journal_file(j.file.as_ref().unwrap().try_clone().unwrap());
+    assert_eq!(r.phase, Some((RUNNING.to_string(), 9)));
+    assert!(from_journal(r, None).fields.get("startup_phase").is_none(), "a running app is past startup");
+    drop(j);
+    let _ = fs::remove_dir_all(&d);
+}