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richiemcilroy merged 4 commits into from
May 12, 2026
Merged

Windows desktop reliability (logs) + onboarding bits #1797

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90bd606
bits
richiemcilroy May 11, 2026
9150f90
Relax comment policy; improve error logging
richiemcilroy May 11, 2026
0b3cbab
Refactor camera setup, unify formatting, update tests
richiemcilroy May 11, 2026
ad8181e
Merge main into windows-crash-stuff
richiemcilroy May 12, 2026
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101 changes: 98 additions & 3 deletions apps/desktop/src-tauri/src/export.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -6,17 +6,55 @@ use cap_rendering::{
FrameRenderer, ProjectRecordingsMeta, ProjectUniforms, RenderSegment, RenderVideoConstants,
RendererLayers, ZoomFocusInterpolator, spring_mass_damper::SpringMassDamperSimulationConfig,
};
use futures::FutureExt;
use image::codecs::jpeg::JpegEncoder;
use serde::{Deserialize, Serialize};
use specta::Type;
use std::any::Any;
use std::panic::AssertUnwindSafe;
use std::{
path::{Path, PathBuf},
sync::{
Arc,
atomic::{AtomicBool, Ordering},
},
};
use tracing::{info, instrument};
use tracing::{error, info, instrument};

fn panic_message(panic: Box<dyn Any + Send>) -> String {
if let Some(msg) = panic.downcast_ref::<&str>() {
msg.to_string()
} else if let Some(msg) = panic.downcast_ref::<String>() {
msg.clone()
} else {
"unknown panic".to_string()
}
}

async fn run_protected_export(
project_path: &Path,
settings: &ExportSettings,
progress: &tauri::ipc::Channel<FramesRendered>,
force_ffmpeg: bool,
) -> Result<PathBuf, String> {
match AssertUnwindSafe(do_export(project_path, settings, progress, force_ffmpeg))
.catch_unwind()
.await
{
Ok(result) => result,
Err(panic) => {
let panic_msg = panic_message(panic);
error!(
target: "cap_desktop_export",
panic = %panic_msg,
"export task panicked"
);
let message = format!("Export task panicked: {panic_msg}");
sentry::capture_message(&message, sentry::Level::Error);
Err(message)
}
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@tembo tembo Bot May 11, 2026

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This currently returns the panic payload as a user-facing Err(String), which can leak internal details (paths, codec strings, etc.) into the UI.

Consider returning a generic error and only sending the panic payload to logs/Sentry.

Suggested change
let message = format!("Export task panicked: {panic_msg}");
sentry::capture_message(&message, sentry::Level::Error);
Err(message)
}
let sentry_message = format!("Export task panicked: {panic_msg}");
sentry::capture_message(&sentry_message, sentry::Level::Error);
Err("Export task panicked".to_string())

}
}
Comment on lines +41 to +59
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@greptile-apps greptile-apps Bot May 11, 2026

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P2 AssertUnwindSafe on retry path

AssertUnwindSafe is correct here — caught panics return Err and the export is abandoned rather than retried into potentially corrupted state. One thing worth double-checking: the retry in export_video (with force_ffmpeg: true) runs immediately after a panic in the GPU path. If the panic leaked an exclusive lock on a WGPU device or left a GPU command encoder in an open state, the retry (even on the software/ffmpeg path) may encounter those residual locks. If you see intermittent hangs on the retry leg during Windows testing, that would be the likely cause.

Prompt To Fix With AI 
This is a comment left during a code review.
Path: apps/desktop/src-tauri/src/export.rs
Line: 41-57

Comment:
**`AssertUnwindSafe` on retry path**

`AssertUnwindSafe` is correct here — caught panics return `Err` and the export is abandoned rather than retried into potentially corrupted state. One thing worth double-checking: the retry in `export_video` (with `force_ffmpeg: true`) runs immediately after a panic in the GPU path. If the panic leaked an exclusive lock on a WGPU device or left a GPU command encoder in an open state, the retry (even on the software/ffmpeg path) may encounter those residual locks. If you see intermittent hangs on the retry leg during Windows testing, that would be the likely cause.

How can I resolve this? If you propose a fix, please make it concise.


struct ExportActiveGuard<'a>(&'a AtomicBool);

Expand Down Expand Up @@ -193,7 +231,7 @@ pub async fn export_video(
wait_for_export_preview_idle(&ed.export_preview_active).await;
}

let result = do_export(&project_path, &settings, &progress, force_ffmpeg).await;
let result = run_protected_export(&project_path, &settings, &progress, force_ffmpeg).await;

match result {
Ok(path) => {
Expand All @@ -206,7 +244,8 @@ pub async fn export_video(
e
);

let retry_result = do_export(&project_path, &settings, &progress, true).await;
let retry_result =
run_protected_export(&project_path, &settings, &progress, true).await;

match retry_result {
Ok(path) => {
Expand Down Expand Up @@ -351,6 +390,35 @@ pub async fn generate_export_preview(
project_path: PathBuf,
frame_time: f64,
settings: ExportPreviewSettings,
) -> Result<ExportPreviewResult, String> {
match AssertUnwindSafe(generate_export_preview_inner(
project_path,
frame_time,
settings,
))
.catch_unwind()
.await
{
Ok(result) => result,
Err(panic) => {
let panic_msg = panic_message(panic);
error!(
target: "cap_desktop_export",
panic = %panic_msg,
"generate_export_preview panicked"
);
let message = format!("Export preview panicked: {panic_msg}");
sentry::capture_message(&message, sentry::Level::Error);
Err(message)
}
}
}

#[instrument(skip_all)]
async fn generate_export_preview_inner(
project_path: PathBuf,
frame_time: f64,
settings: ExportPreviewSettings,
) -> Result<ExportPreviewResult, String> {
use base64::{Engine, engine::general_purpose::STANDARD};
use cap_editor::create_segments;
Expand Down Expand Up @@ -593,6 +661,33 @@ pub async fn generate_export_preview_fast(
editor: WindowEditorInstance,
frame_time: f64,
settings: ExportPreviewSettings,
) -> Result<ExportPreviewResult, String> {
match AssertUnwindSafe(generate_export_preview_fast_inner(
editor, frame_time, settings,
))
.catch_unwind()
.await
{
Ok(result) => result,
Err(panic) => {
let panic_msg = panic_message(panic);
error!(
target: "cap_desktop_export",
panic = %panic_msg,
"generate_export_preview_fast panicked"
);
let message = format!("Export preview panicked: {panic_msg}");
sentry::capture_message(&message, sentry::Level::Error);
Err(message)
}
}
}

#[instrument(skip_all)]
async fn generate_export_preview_fast_inner(
editor: WindowEditorInstance,
frame_time: f64,
settings: ExportPreviewSettings,
) -> Result<ExportPreviewResult, String> {
use base64::{Engine, engine::general_purpose::STANDARD};
use std::time::Instant;
Expand Down
81 changes: 79 additions & 2 deletions apps/desktop/src-tauri/src/main.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -12,6 +12,13 @@ fn main() {
std::env::set_var("RUST_LOG", "trace");
}

#[cfg(not(debug_assertions))]
if std::env::var_os("RUST_BACKTRACE").is_none() {
unsafe {
std::env::set_var("RUST_BACKTRACE", "full");
}
}

// We have to hold onto the ClientInitGuard until the very end
let _sentry_guard = std::option_env!("CAP_DESKTOP_SENTRY_URL").map(|url| {
let sentry_client = sentry::init((
Expand Down Expand Up @@ -72,7 +79,6 @@ fn main() {
});

let file_appender = tracing_appender::rolling::daily(&logs_dir, "cap-desktop.log");
let (non_blocking, _logger_guard) = tracing_appender::non_blocking(file_appender);

let (otel_layer, _tracer) = if cfg!(debug_assertions) {
use opentelemetry::trace::TracerProvider;
Expand Down Expand Up @@ -125,10 +131,12 @@ fn main() {
tracing_subscriber::fmt::layer()
.with_ansi(false)
.with_target(true)
.with_writer(non_blocking),
.with_writer(file_appender),
)
.init();

install_panic_hook(logs_dir.clone());

#[cfg(debug_assertions)]
sentry::configure_scope(|scope| {
scope.set_user(Some(sentry::User {
Expand All @@ -143,3 +151,72 @@ fn main() {
.expect("Failed to build multi threaded tokio runtime")
.block_on(cap_desktop_lib::run(handle, logs_dir));
}

fn install_panic_hook(logs_dir: std::path::PathBuf) {
let prev = std::panic::take_hook();
let panics_log = logs_dir.join("panics.log");
std::panic::set_hook(Box::new(move |info| {
let location = info
.location()
.map(|l| format!("{}:{}:{}", l.file(), l.line(), l.column()))
.unwrap_or_else(|| "<unknown>".to_string());
let message = info
.payload()
Comment on lines +163 to +168
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@greptile-apps greptile-apps Bot May 11, 2026

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P2 RUST_BACKTRACE has no effect on Backtrace::force_capture()

std::backtrace::Backtrace::force_capture() (used in the panic hook) always captures a backtrace regardless of the RUST_BACKTRACE environment variable — that is the point of force_capture vs capture. The env-var block therefore only affects the default Rust panic handler (prev(info) call at the end of the hook). This works as intended for the default handler, but the block is misleading and could be removed without changing what ends up in panics.log.

Prompt To Fix With AI 
This is a comment left during a code review.
Path: apps/desktop/src-tauri/src/main.rs
Line: 159-164

Comment:
**`RUST_BACKTRACE` has no effect on `Backtrace::force_capture()`**

`std::backtrace::Backtrace::force_capture()` (used in the panic hook) always captures a backtrace regardless of the `RUST_BACKTRACE` environment variable — that is the point of `force_capture` vs `capture`. The env-var block therefore only affects the *default* Rust panic handler (`prev(info)` call at the end of the hook). This works as intended for the default handler, but the block is misleading and could be removed without changing what ends up in `panics.log`.

How can I resolve this? If you propose a fix, please make it concise.

.downcast_ref::<&str>()
.map(|s| (*s).to_string())
.or_else(|| info.payload().downcast_ref::<String>().cloned())
.unwrap_or_else(|| "<no message>".to_string());
let backtrace = std::backtrace::Backtrace::force_capture();
let thread = std::thread::current();
let thread_name = thread.name().unwrap_or("<unnamed>").to_string();
let timestamp = chrono::Utc::now().to_rfc3339();
let pid = std::process::id();

write_panic_record(
&panics_log,
&timestamp,
pid,
&thread_name,
&location,
&message,
&backtrace,
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P2 Synchronous file writer in async context

Replacing tracing_appender::non_blocking with a direct RollingFileAppender makes every tracing call block the calling thread until the write is flushed to disk. Inside Tokio worker threads (recording pipeline, export, preview rendering) this can stall the runtime and introduce latency spikes. If the goal is to ensure no logs are dropped on Windows, consider keeping non_blocking but explicitly flushing the guard on shutdown, or using tracing_appender::non_blocking with lossy = false.

Prompt To Fix With AI 
This is a comment left during a code review.
Path: apps/desktop/src-tauri/src/main.rs
Line: 182

Comment:
**Synchronous file writer in async context**

Replacing `tracing_appender::non_blocking` with a direct `RollingFileAppender` makes every `tracing` call block the calling thread until the write is flushed to disk. Inside Tokio worker threads (recording pipeline, export, preview rendering) this can stall the runtime and introduce latency spikes. If the goal is to ensure no logs are dropped on Windows, consider keeping `non_blocking` but explicitly flushing the guard on shutdown, or using `tracing_appender::non_blocking` with `lossy = false`.

How can I resolve this? If you propose a fix, please make it concise.

);

tracing::error!(
target: "cap_desktop_panic",
location = %location,
thread = %thread_name,
message = %message,
backtrace = %backtrace,
"panic"
);
eprintln!(
"[cap-desktop panic] thread '{thread_name}' at {location}: {message}\nbacktrace:\n{backtrace}"
);
prev(info);
}));
}

fn write_panic_record(
path: &std::path::Path,
timestamp: &str,
pid: u32,
thread_name: &str,
location: &str,
message: &str,
backtrace: &std::backtrace::Backtrace,
) {
use std::io::Write;
let Ok(mut file) = std::fs::OpenOptions::new()
.create(true)
.append(true)
.open(path)
else {
return;
};
let _ = writeln!(
file,
"[{timestamp}] pid={pid} thread='{thread_name}' at {location}: {message}\n{backtrace}\n----"
);
let _ = file.flush();
}
4 changes: 2 additions & 2 deletions apps/desktop/src/components/ModeSelect.tsx
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Original file line number Diff line number Diff line change
Expand Up @@ -15,7 +15,7 @@ interface ModeOptionProps {
const ModeOption = (props: ModeOptionProps) => {
return (
<div
data-tauri-drag-region="none"
data-tauri-drag-region="false"
onClick={() => props.onSelect(props.mode)}
class={cx(
"relative flex flex-col items-center rounded-xl border-2 transition-all duration-200 cursor-pointer overflow-hidden group",
Expand Down Expand Up @@ -84,7 +84,7 @@ const ModeSelect = (props: { onClose?: () => void; standalone?: boolean }) => {

return (
<div
data-tauri-drag-region="none"
data-tauri-drag-region="false"
class={cx(
"relative",
props.standalone
Expand Down
2 changes: 1 addition & 1 deletion apps/desktop/src/routes/(window-chrome).tsx
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Original file line number Diff line number Diff line change
Expand Up @@ -114,7 +114,7 @@ function Inner(props: ParentProps) {

return (
<div
data-tauri-drag-region="none"
data-tauri-drag-region="false"
class="flex overflow-y-hidden flex-col flex-1 animate-in fade-in"
>
{props.children}
Expand Down
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