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Desktop: write log records to standard error and a rotating log file 

A launch from the Dock, the Start menu or a launcher has no terminal, and
without RUST_LOG nothing reached standard error anyway, so start-up and
GPU warnings were lost unless Help > Enable Logging was already on.

The logger now writes EffectCraft's info records and everyone's warnings
to standard error and to Logs/effectcraft.log in the settings folder.
Each launch keeps the previous two runs' logs; the file is capped at
16 MiB. RUST_LOG still overrides the filter. Help > Reveal Logging File
shows this run's log unless Enable Logging is on.

Ported from storytold/pdfcraft#239.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
This commit is contained in:
Fabio Lussi 2026-10-11 22:37:27 +02:00
parent 67434e9038
commit 16d9d7d30b
6 changed files with 347 additions and 39 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

4
apps/effectcraft/src/audio_out.rs
View File

@ -117,7 +117,7 @@ fn run<T: SizedSample + FromSample<f32>>(
let dev_lat = ts.playback.duration_since(&ts.callback).map(|d| d.as_secs_f64()).unwrap_or(0.0);
latency.store((dev_lat * rate) as u64 + frames as u64, Ordering::Relaxed);
},
|e| eprintln!("effectcraft: audio output: {e}"),
|e| log::warn!("audio output: {e}"),
None,
)
.map_err(|e| e.to_string())
@ -187,7 +187,7 @@ impl AudioDevice for CpalOut {
return;
}
if let Err(e) = stream.play() {
eprintln!("effectcraft: audio output: {e}");
log::warn!("audio output: {e}");
return;
}
let _ = stop_rx.recv();

4
apps/effectcraft/src/control_server.rs
View File

@ -27,11 +27,11 @@ pub fn start(port: u16, ctx: egui::Context) -> Receiver<ControlRequest> {
let listener = match TcpListener::bind(("127.0.0.1", port)) {
Ok(l) => l,
Err(e) => {
eprintln!("effectcraft: control server failed to bind 127.0.0.1:{port}: {e}");
log::error!("control server failed to bind 127.0.0.1:{port}: {e}");
return rx;
}
};
eprintln!("effectcraft: control server listening on 127.0.0.1:{port}");
log::info!("control server listening on 127.0.0.1:{port}");
std::thread::spawn(move || accept_loop(listener, tx, ctx));
rx
}

29
apps/effectcraft/src/main.rs
View File

@ -88,13 +88,24 @@ fn parse_args(args: impl IntoIterator<Item = String>, env_port: Option<String>)
}
fn main() -> eframe::Result {
// Help ▸ Enable Logging writes through this logger; warnings feed the compatibility report.
// First, so the panic hook and every start-up warning are recorded. Records go to stderr
// and the session log; Help ▸ Enable Logging writes through this logger too, and warnings
// feed the compatibility report.
effectcraft_engine::logging::install();
effectcraft_engine::logging::install_panic_hook();
let Some(Args { control_port, files, demo, home }) = parse_args(std::env::args().skip(1), std::env::var("EFFECTCRAFT_CONTROL_PORT").ok()) else {
println!("effectcraft {}", env!("CARGO_PKG_VERSION"));
return Ok(());
};
// The session log lives in the settings folder (`Logs/effectcraft.log`, the previous two runs
// kept): a launch from the Dock or a menu has no terminal. Opened after the arguments, so
// `--version` leaves no file behind; records logged until now are written to it first.
if let Some(dir) = effectcraft_host::config_dir() {
match effectcraft_engine::logging::attach_session_log(&effectcraft_engine::logging::log_dir(Some(&dir))) {
Ok(path) => log::info!("effectcraft {}, log file {}", env!("CARGO_PKG_VERSION"), path.display()),
Err(e) => log::warn!("no log file: {e}"),
}
}
// The font menus list the installed fonts: read their names while the window opens.
effectcraft_engine::text::fonts::scan_system_in_background();
// Wayland shows the window's icon from its desktop entry: an AppImage brings its own.
@ -120,8 +131,8 @@ fn main() -> eframe::Result {
wgpu_options: wgpu_options(launch.backends),
..Default::default()
};
// Start-up milestones: with `RUST_LOG=info` they go to stderr, so a window that never
// appears shows how far start-up got (#234).
// Start-up milestones go to stderr and the session log, so a window that never appears
// shows how far start-up got (#234).
log::info!("effectcraft {}: opening the window", env!("CARGO_PKG_VERSION"));
// Registered before the event loop starts, so it catches the Finder event that launched us as
// well as later ones. Lives until the event loop returns; the app creator only borrows it.
@ -174,7 +185,7 @@ fn main() -> eframe::Result {
let project = files.iter().find(|f| is_project_file(f)).cloned();
if let Some(p) = project {
if let Err(e) = session.execute("file.open", json!({"path": p})) {
eprintln!("effectcraft: {e}");
log::warn!("{p}: {e}");
}
} else if demo {
let _ = session.execute("file.openDemoProject", json!({}));
@ -183,7 +194,7 @@ fn main() -> eframe::Result {
if !media.is_empty()
&& let Err(e) = session.execute("file.import", json!({"paths": media}))
{
eprintln!("effectcraft: {e}");
log::warn!("import: {e}");
}
let show_home = home.unwrap_or(session.prefs.startup.show_home_on_launch && files.is_empty() && control_port.is_none());
// The ScriptUI panels open when the app last quit open again (a failing one is
@ -315,8 +326,12 @@ fn startup_failed(e: &eframe::Error, gl_next: bool) {
let message = format!(
"EffectCraft couldn't start its window: {e}\n\n{next}Updating the graphics driver often helps. If it keeps happening, please report it at https://github.com/storytold/effectcraft/issues with this message."
);
log::error!("{message}");
eprintln!("effectcraft: {message}");
// Standard error and the session log; standard error alone when RUST_LOG turned errors off.
if log::log_enabled!(log::Level::Error) {
log::error!("{message}");
} else {
eprintln!("effectcraft: {message}");
}
let _ = rfd::MessageDialog::new()
.set_level(rfd::MessageLevel::Error)
.set_title("EffectCraft")

7
crates/engine/src/commands/app_more.rs
View File

@ -288,7 +288,12 @@ fn enable_logging(s: &mut Session, p: &Value) -> Result<Value> {
}
fn reveal_log(s: &mut Session, _: &Value) -> Result<Value> {
let file = crate::logging::current_file().unwrap_or_else(|| log_file(s));
// Enable Logging's file while it is on, else this run's session log.
let file = crate::logging::current_file()
.filter(|_| crate::logging::is_enabled())
.or_else(crate::logging::session_file)
.or_else(crate::logging::current_file)
.unwrap_or_else(|| log_file(s));
let path = file.to_string_lossy().to_string();
let url = super::layer_menu::folder_url(&path);
s.events.push(Event::OpenUrl(url.clone()));

328
crates/engine/src/logging.rs
View File

@ -1,25 +1,47 @@
//! Help ▸ Enable Logging / Reveal Logging File: a `log` logger that, while enabled, appends
//! every record to `Logs/EffectCraft Log.txt` in the settings folder (or the temporary folder),
//! and always keeps the last few hundred warnings and errors in memory for the System
//! Compatibility Report.
//! The `log` logger. Records go to standard error and, on the desktop, to a session log that
//! every launch starts afresh: `Logs/effectcraft.log` in the settings folder, with the two runs
//! before it kept as `effectcraft.1.log` and `effectcraft.2.log`, so the log of a run that
//! crashed survives the next start. A launch from the Dock, the Start menu or a launcher has no
//! terminal, so that file is what a bug report can attach. The last few hundred warnings and
//! errors are also kept in memory for the System Compatibility Report.
//!
//! Frontends call [`install`] once at startup; [`set_enabled`] (the `help.enableLogging`
//! command) turns file logging on and off. `RUST_LOG` (a level such as `debug`, or per target:
//! `effectcraft=debug,wgpu=warn`) also prints what it lets through to stderr, so a start-up that
//! fails before the window opens leaves a trace.
//! Levels: `info` for EffectCraft's own crates, `warn` for everything else (wgpu and naga are
//! chatty). `RUST_LOG` replaces that (a level such as `debug`, or per target:
//! `effectcraft=debug,wgpu=warn`).
//!
//! Help ▸ Enable Logging ([`set_enabled`], the `help.enableLogging` command) additionally appends
//! every EffectCraft record to `Logs/EffectCraft Log.txt`, across launches.
//!
//! Frontends call [`install`] once at startup and the desktop app [`attach_session_log`] once the
//! settings folder is known; records logged before that are kept (up to [`MAX_PENDING`]) and
//! written first. Writing never panics: a file that can't be created or written leaves standard
//! error as the only sink. Never log the control-channel token.
use std::collections::VecDeque;
use std::fs::File;
use std::io::Write;
use std::path::{Path, PathBuf};
use std::sync::atomic::{AtomicBool, Ordering};
use std::sync::{Mutex, OnceLock};
use std::sync::{Mutex, OnceLock, PoisonError};
use log::LevelFilter;
/// The session log's name inside the `Logs` folder.
pub const SESSION_LOG: &str = "effectcraft.log";
/// How many previous session logs are kept (`effectcraft.1.log` … `effectcraft.<KEEP>.log`).
pub const KEEP: usize = 2;
/// The session log stops growing past this size (a runaway warning can't fill the disk).
pub const MAX_FILE_BYTES: u64 = 16 * 1024 * 1024;
/// Records kept in memory until the session log is attached.
pub const MAX_PENDING: usize = 512;
/// The filter when `RUST_LOG` is unset or empty.
pub const DEFAULT_FILTER: &str = "warn,effectcraft=info";
static ENABLED: AtomicBool = AtomicBool::new(false);
/// The `RUST_LOG` filter for stderr: (target prefix or every target, level).
static STDERR: OnceLock<Vec<(Option<String>, LevelFilter)>> = OnceLock::new();
/// The filter for standard error and the session log: (target prefix or every target, level).
static FILTER: OnceLock<Vec<(Option<String>, LevelFilter)>> = OnceLock::new();
static STATE: Mutex<State> = Mutex::new(State { file: None, recent: VecDeque::new() });
static SESSION: Mutex<Sink> = Mutex::new(Sink::new(MAX_FILE_BYTES));
struct State {
file: Option<PathBuf>,
@ -32,15 +54,16 @@ const RECENT: usize = 300;
impl log::Log for Logger {
fn enabled(&self, m: &log::Metadata) -> bool {
m.level() <= log::Level::Warn || (ENABLED.load(Ordering::Relaxed) && m.target().starts_with("effectcraft")) || to_stderr(m)
m.level() <= log::Level::Warn || (ENABLED.load(Ordering::Relaxed) && m.target().starts_with("effectcraft")) || shown(m)
}
fn log(&self, r: &log::Record) {
if !self.enabled(r.metadata()) {
return;
}
let line = format!("{} {:<5} {}: {}", unix_secs(), r.level(), r.target(), r.args());
if to_stderr(r.metadata()) {
eprintln!("{line}");
let line = format_line(&timestamp(unix_millis()), r.level(), &thread_name(), r.target(), &r.args().to_string());
if shown(r.metadata()) {
let _ = writeln!(std::io::stderr(), "{line}");
SESSION.lock().unwrap_or_else(PoisonError::into_inner).write(&format!("{line}\n"));
}
let Ok(mut st) = STATE.lock() else { return };
if r.level() <= log::Level::Warn {
@ -59,22 +82,62 @@ impl log::Log for Logger {
fn flush(&self) {}
}
fn unix_secs() -> u64 {
web_time::SystemTime::now().duration_since(web_time::UNIX_EPOCH).map(|d| d.as_secs()).unwrap_or(0)
fn unix_millis() -> u64 {
web_time::SystemTime::now().duration_since(web_time::UNIX_EPOCH).map(|d| u64::try_from(d.as_millis()).unwrap_or(u64::MAX)).unwrap_or(0)
}
fn thread_name() -> String {
#[cfg(not(target_arch = "wasm32"))]
return std::thread::current().name().unwrap_or("?").to_string();
#[cfg(target_arch = "wasm32")]
return "main".to_string();
}
/// `2026-10-08T07:59:17.728Z` (UTC, milliseconds) for `ms` milliseconds since 1970.
fn timestamp(ms: u64) -> String {
let secs = ms / 1000;
let (days, rem) = (secs / 86_400, secs % 86_400);
let (y, m, d) = civil_from_days(days);
format!("{y:04}-{m:02}-{d:02}T{:02}:{:02}:{:02}.{:03}Z", rem / 3600, rem % 3600 / 60, rem % 60, ms % 1000)
}
/// Days since 1970-01-01 to a proleptic Gregorian (year, month, day) (Howard Hinnant's
/// `civil_from_days`, unsigned since the clock is clamped at the epoch). `days` is at most
/// `u64::MAX / 86_400_000`, so none of the arithmetic below can overflow.
fn civil_from_days(days: u64) -> (u64, u64, u64) {
let z = days + 719_468;
let era = z / 146_097;
let doe = z % 146_097;
let yoe = (doe - doe / 1460 + doe / 36_524 - doe / 146_096) / 365;
let doy = doe - (365 * yoe + yoe / 4 - yoe / 100);
let mp = (5 * doy + 2) / 153;
let d = doy - (153 * mp + 2) / 5 + 1;
let m = if mp < 10 { mp + 3 } else { mp - 9 };
let y = yoe + era * 400 + u64::from(m <= 2);
(y, m, d)
}
/// One log line (without the newline): `<timestamp> <LEVEL> [<thread>] <target>: <message>`.
fn format_line(ts: &str, level: log::Level, thread: &str, target: &str, message: &str) -> String {
let message = message.strip_suffix('\n').unwrap_or(message);
format!("{ts} {level:<5} [{thread}] {target}: {message}")
}
/// Install the logger (once; later calls and other installed loggers are left alone).
pub fn install() {
static LOGGER: Logger = Logger;
if log::set_logger(&LOGGER).is_ok() {
let stderr = STDERR.get_or_init(|| std::env::var("RUST_LOG").map(|s| parse_filter(&s)).unwrap_or_default());
log::set_max_level(stderr.iter().map(|d| d.1).fold(LevelFilter::Info, Ord::max));
let filter = FILTER.get_or_init(|| {
let spec = std::env::var("RUST_LOG").ok().filter(|s| !s.trim().is_empty());
parse_filter(spec.as_deref().unwrap_or(DEFAULT_FILTER))
});
log::set_max_level(filter.iter().map(|d| d.1).fold(LevelFilter::Info, Ord::max));
}
}
/// Whether `RUST_LOG` lets a record through to stderr.
fn to_stderr(m: &log::Metadata) -> bool {
STDERR.get().is_some_and(|f| m.level() <= level_for(f, m.target()))
/// Whether the filter lets a record through to standard error and the session log.
fn shown(m: &log::Metadata) -> bool {
FILTER.get().is_some_and(|f| m.level() <= level_for(f, m.target()))
}
/// `RUST_LOG`'s directives, as env_logger reads them: `level`, `target=level` or a bare target
@ -110,9 +173,112 @@ pub fn install_panic_hook() {
}));
}
/// The log file inside `config_dir` (the settings folder), or the temporary folder.
/// The `Logs` folder inside `config_dir` (the settings folder), or in the temporary folder.
pub fn log_dir(config_dir: Option<&Path>) -> PathBuf {
config_dir.map(Path::to_path_buf).unwrap_or_else(std::env::temp_dir).join("Logs")
}
/// Help ▸ Enable Logging's file inside `config_dir` (the settings folder), or the temporary folder.
pub fn log_path(config_dir: Option<&Path>) -> PathBuf {
config_dir.map(Path::to_path_buf).unwrap_or_else(std::env::temp_dir).join("Logs").join("EffectCraft Log.txt")
log_dir(config_dir).join("EffectCraft Log.txt")
}
fn numbered(dir: &Path, n: usize) -> PathBuf {
if n == 0 { dir.join(SESSION_LOG) } else { dir.join(format!("effectcraft.{n}.log")) }
}
/// Shift the previous session logs up one (`.log` → `.1.log` → … → `.<KEEP>.log`, the oldest
/// dropped) and create a fresh, empty log file in `dir` (created if missing).
fn rotate(dir: &Path) -> std::io::Result<(PathBuf, File)> {
std::fs::create_dir_all(dir)?;
for n in (1..=KEEP).rev() {
match std::fs::rename(numbered(dir, n - 1), numbered(dir, n)) {
Err(e) if e.kind() != std::io::ErrorKind::NotFound => return Err(e),
_ => {}
}
}
let path = numbered(dir, 0);
let file = File::create(&path)?;
Ok((path, file))
}
/// Rotate the session logs in `dir` (the `Logs` folder, see [`log_dir`]) and write records to
/// a fresh `effectcraft.log` there, first the ones logged so far; returns its path.
pub fn attach_session_log(dir: &Path) -> Result<PathBuf, String> {
let (path, file) = rotate(dir).map_err(|e| format!("{}: {e}", dir.display()))?;
let mut sink = SESSION.lock().unwrap_or_else(PoisonError::into_inner);
sink.attach(file);
sink.path = Some(path.clone());
Ok(path)
}
/// This run's session log (once [`attach_session_log`] succeeded).
pub fn session_file() -> Option<PathBuf> {
SESSION.lock().unwrap_or_else(PoisonError::into_inner).path.clone()
}
/// Where lines go besides standard error: kept in memory until a file is attached, then
/// appended to it until it reaches its size cap.
struct Sink {
file: Option<File>,
path: Option<PathBuf>,
pending: Vec<String>,
dropped: usize,
written: u64,
max_bytes: u64,
capped: bool,
}
impl Sink {
const fn new(max_bytes: u64) -> Sink {
Sink { file: None, path: None, pending: Vec::new(), dropped: 0, written: 0, max_bytes, capped: false }
}
/// Append `line` to the file, or keep it until [`Sink::attach`].
fn write(&mut self, line: &str) {
if self.file.is_none() && !self.capped {
if self.pending.len() < MAX_PENDING {
self.pending.push(line.to_owned());
} else {
self.dropped = self.dropped.saturating_add(1);
}
return;
}
self.append(line);
}
/// Start writing to `file`, first the lines kept so far.
fn attach(&mut self, file: File) {
self.file = Some(file);
for line in std::mem::take(&mut self.pending) {
self.append(&line);
}
if self.dropped > 0 {
let note = format!("{} earlier log lines were dropped before the log file was opened\n", self.dropped);
self.dropped = 0;
self.append(&note);
}
}
fn append(&mut self, line: &str) {
if self.capped {
return;
}
let Some(file) = self.file.as_mut() else { return };
let len = u64::try_from(line.len()).unwrap_or(u64::MAX);
let text = if self.written.saturating_add(len) > self.max_bytes {
self.capped = true;
format!("log file reached {} bytes; later records go to standard error only\n", self.max_bytes)
} else {
self.written = self.written.saturating_add(len);
line.to_owned()
};
// A full disk or a vanished file must not take the app down: drop the file sink.
if file.write_all(text.as_bytes()).is_err() {
self.file = None;
self.capped = true;
}
}
}
/// Turn file logging on (writing to `file`) or off.
@ -123,7 +289,7 @@ pub fn set_enabled(on: bool, file: PathBuf) -> std::io::Result<()> {
std::fs::create_dir_all(d)?;
}
let mut f = std::fs::OpenOptions::new().create(true).append(true).open(&file)?;
writeln!(f, "{} INFO effectcraft: logging enabled ({} {})", unix_secs(), std::env::consts::OS, env!("CARGO_PKG_VERSION"))?;
writeln!(f, "{} INFO effectcraft: logging enabled ({} {})", timestamp(unix_millis()), std::env::consts::OS, env!("CARGO_PKG_VERSION"))?;
}
if let Ok(mut st) = STATE.lock() {
st.file = Some(file);
@ -136,7 +302,7 @@ pub fn is_enabled() -> bool {
ENABLED.load(Ordering::Relaxed)
}
/// The current log file (set once logging was enabled).
/// The current Enable Logging file (set once logging was enabled).
pub fn current_file() -> Option<PathBuf> {
STATE.lock().ok().and_then(|s| s.file.clone())
}
@ -148,7 +314,8 @@ pub fn recent() -> Vec<String> {
#[cfg(test)]
mod tests {
use super::{LevelFilter, level_for, parse_filter};
use super::*;
use std::sync::atomic::AtomicUsize;
/// `RUST_LOG` picks what start-up prints to stderr (#234).
#[test]
@ -162,4 +329,111 @@ mod tests {
assert_eq!(level_for(&parse_filter("wgpu=debug"), "winit"), LevelFilter::Off);
assert!(parse_filter("").is_empty());
}
fn temp_dir(tag: &str) -> PathBuf {
static N: AtomicUsize = AtomicUsize::new(0);
let d = std::env::temp_dir().join(format!("effectcraft-logging-{tag}-{}-{}", std::process::id(), N.fetch_add(1, Ordering::Relaxed)));
let _ = std::fs::remove_dir_all(&d);
d
}
fn read(path: &Path) -> String {
std::fs::read_to_string(path).unwrap()
}
/// Without `RUST_LOG`, EffectCraft's own info records and everyone's warnings are shown.
#[test]
fn the_default_filter_shows_effectcraft_info_and_other_crates_warnings() {
let f = parse_filter(DEFAULT_FILTER);
assert_eq!(level_for(&f, "effectcraft"), LevelFilter::Info);
assert_eq!(level_for(&f, "effectcraft_ui_egui::app"), LevelFilter::Info);
assert_eq!(level_for(&f, "wgpu_core::device"), LevelFilter::Warn);
assert_eq!(level_for(&f, "naga"), LevelFilter::Warn);
}
#[test]
fn timestamps_are_utc_with_milliseconds() {
assert_eq!(timestamp(0), "1970-01-01T00:00:00.000Z");
assert_eq!(timestamp(1_791_446_357_728), "2026-10-08T07:59:17.728Z");
assert_eq!(timestamp(1_709_164_800_000), "2024-02-29T00:00:00.000Z");
assert_eq!(timestamp(951_782_400_000), "2000-02-29T00:00:00.000Z");
assert_eq!(timestamp(1_767_225_599_000), "2025-12-31T23:59:59.000Z");
let _ = timestamp(u64::MAX);
}
/// Each launch keeps the previous runs' logs, so the log of a run that crashed survives.
#[test]
fn rotation_keeps_the_previous_logs_and_starts_an_empty_file() {
let dir = temp_dir("rotate");
for run in 1..=4 {
let (path, _file) = rotate(&dir).unwrap();
assert_eq!(path, dir.join(SESSION_LOG));
assert_eq!(read(&path), "");
std::fs::write(&path, format!("run {run}")).unwrap();
}
assert_eq!(read(&dir.join(SESSION_LOG)), "run 4");
assert_eq!(read(&dir.join("effectcraft.1.log")), "run 3");
assert_eq!(read(&dir.join("effectcraft.2.log")), "run 2");
assert!(!dir.join("effectcraft.3.log").exists(), "only {KEEP} old logs are kept");
let _ = std::fs::remove_dir_all(&dir);
}
#[test]
fn rotation_into_an_unusable_directory_is_an_error_not_a_panic() {
let dir = temp_dir("blocked");
std::fs::write(&dir, "a file where the directory should be").unwrap();
assert!(rotate(&dir).is_err());
let _ = std::fs::remove_file(&dir);
}
#[test]
fn lines_logged_before_the_file_exists_are_written_when_it_is_attached() {
let dir = temp_dir("pending");
let (path, file) = rotate(&dir).unwrap();
let mut sink = Sink::new(MAX_FILE_BYTES);
sink.write("early 1\n");
sink.write("early 2\n");
sink.attach(file);
sink.write("late\n");
assert_eq!(read(&path), "early 1\nearly 2\nlate\n");
let _ = std::fs::remove_dir_all(&dir);
}
#[test]
fn the_pending_buffer_is_bounded_and_says_how_much_it_dropped() {
let dir = temp_dir("bounded");
let (path, file) = rotate(&dir).unwrap();
let mut sink = Sink::new(MAX_FILE_BYTES);
for i in 0..MAX_PENDING + 5 {
sink.write(&format!("line {i}\n"));
}
sink.attach(file);
let text = read(&path);
assert_eq!(text.lines().filter(|l| l.starts_with("line ")).count(), MAX_PENDING);
assert_eq!(text.matches("5 earlier log lines were dropped").count(), 1, "{text}");
let _ = std::fs::remove_dir_all(&dir);
}
#[test]
fn the_file_stops_at_its_size_cap_with_one_note() {
let dir = temp_dir("cap");
let (path, file) = rotate(&dir).unwrap();
let mut sink = Sink::new(100);
sink.attach(file);
for i in 0..50 {
sink.write(&format!("line {i:02} with some padding\n"));
}
let text = read(&path);
assert!(text.lines().filter(|l| l.starts_with("line ")).count() < 5, "{text}");
assert_eq!(text.matches("log file reached").count(), 1, "{text}");
let _ = std::fs::remove_dir_all(&dir);
}
#[test]
fn a_line_carries_time_level_thread_target_and_message() {
assert_eq!(
format_line("2026-10-08T07:59:17.728Z", log::Level::Warn, "main", "effectcraft_engine::autosave", "disk full\n"),
"2026-10-08T07:59:17.728Z WARN [main] effectcraft_engine::autosave: disk full"
);
}
}

14
docs/preferences.md
View File

@ -223,3 +223,17 @@ checkpoint after a client restart.
Commands: `file.autoSave` (now), `file.recoveryInfo`, `file.openRecent {index? | path?}`,
`file.clearRecent`, `file.revert`, `file.incrementAndSave`.
## Logs
The desktop app writes its log records to standard error and to `Logs/effectcraft.log` in the
config directory. Each launch moves the previous log to `effectcraft.1.log` (and that one to
`effectcraft.2.log`), so the log of a run that crashed survives the next start; a log stops
growing at 16 MiB. A launch from the Dock, the Start menu or a launcher has no terminal, so
attach these files to a bug report. Help ▸ Reveal Logging File shows this run's log (or Help ▸
Enable Logging's `EffectCraft Log.txt` while that is on, which keeps every EffectCraft record
across launches).
By default the log has `info` records from EffectCraft and warnings and errors from everything
else. `RUST_LOG` replaces that with env_logger-style directives: `debug`,
`warn,effectcraft_render=trace`, `wgpu_core=info`. The control-channel token is never logged.