crates/dtmm/src/controller/app.rs

@@ -9,7 +9,7 @@ use druid::im::Vector;
 use druid::{FileInfo, ImageBuf};
 use dtmt_shared::ModConfig;
 use nexusmods::Api as NexusApi;
-use tokio::fs::{self, DirEntry};
+use tokio::fs::{self, DirEntry, File};
 use tokio_stream::wrappers::ReadDirStream;
 use tokio_stream::StreamExt;
 use zip::ZipArchive;
@@ -424,6 +424,13 @@ pub(crate) async fn load_initial(path: PathBuf, is_default: bool) -> Result<Init
         .await
         .wrap_err("Failed to read config file")?;
 
+    // Create or truncate the log file
+    let log_path = config.data_dir.join("dtmm.log");
+    tokio::spawn(async move {
+        let _ = File::create(&log_path).await;
+        tracing::debug!("Truncated log file");
+    });
+
     let game_info = tokio::task::spawn_blocking(dtmt_shared::collect_game_info)
         .await
         .wrap_err("Failed to collect Steam game info")?;

crates/dtmm/src/controller/worker.rs

@@ -5,7 +5,10 @@ use color_eyre::Help;
 use color_eyre::Report;
 use color_eyre::Result;
 use druid::{ExtEventSink, SingleUse, Target};
+use tokio::fs::OpenOptions;
+use tokio::io::AsyncWriteExt;
 use tokio::runtime::Runtime;
+
 use tokio::sync::mpsc::UnboundedReceiver;
 use tokio::sync::RwLock;
 
@@ -168,6 +171,15 @@ async fn handle_action(
                     )
                     .expect("failed to send command");
             }),
+            AsyncAction::Log((state, line)) => tokio::spawn(async move {
+                if let Ok(mut f) = OpenOptions::new()
+                    .append(true)
+                    .open(state.data_dir.join("dtmm.log"))
+                    .await
+                {
+                    let _ = f.write_all(&line).await;
+                }
+            }),
         };
     }
 }

crates/dtmm/src/main.rs

@@ -6,10 +6,8 @@
 use std::path::PathBuf;
 use std::sync::Arc;
 
-use clap::command;
 use clap::parser::ValueSource;
-use clap::value_parser;
-use clap::Arg;
+use clap::{command, value_parser, Arg};
 use color_eyre::eyre;
 use color_eyre::{Report, Result};
 use druid::AppLauncher;
@@ -19,6 +17,7 @@ use crate::controller::worker::work_thread;
 use crate::state::AsyncAction;
 use crate::state::{Delegate, State};
 use crate::ui::theme;
+use crate::util::log::LogLevel;
 
 mod controller;
 mod state;
@@ -46,10 +45,22 @@ fn main() -> Result<()> {
                 .value_parser(value_parser!(PathBuf))
                 .default_value(default_config_path.to_string_lossy().to_string()),
         )
+        .arg(
+            Arg::new("log-level")
+                .long("log-level")
+                .help("The maximum level of log events to print")
+                .value_parser(value_parser!(LogLevel))
+                .default_value("info"),
+        )
         .get_matches();
 
     let (log_tx, log_rx) = tokio::sync::mpsc::unbounded_channel();
-    util::log::create_tracing_subscriber(log_tx);
+    let level = if matches.value_source("log-level") == Some(ValueSource::DefaultValue) {
+        None
+    } else {
+        matches.get_one::<LogLevel>("log-level").cloned()
+    };
+    util::log::create_tracing_subscriber(log_tx, level);
 
     let (action_tx, action_rx) = tokio::sync::mpsc::unbounded_channel();
 

crates/dtmm/src/state/delegate.rs

@@ -92,6 +92,7 @@ pub(crate) enum AsyncAction {
     SaveSettings(ActionState),
     CheckUpdates(ActionState),
     LoadInitial((PathBuf, bool)),
+    Log((ActionState, Vec<u8>)),
 }
 
 pub(crate) struct Delegate {
@@ -253,10 +254,22 @@ impl AppDelegate<State> for Delegate {
                 let line = cmd
                     .get(ACTION_LOG)
                     .expect("command type matched but didn't contain the expected value");
+
                 if let Some(line) = line.take() {
-                    let line = String::from_utf8_lossy(&line);
-                    state.log.push_back(ansi_to_rich_text(line.trim()));
+                    {
+                        let line = String::from_utf8_lossy(&line);
+                        state.log.push_back(ansi_to_rich_text(line.trim()));
+                    }
+
+                    if self
+                        .sender
+                        .send(AsyncAction::Log((state.clone().into(), line)))
+                        .is_err()
+                    {
+                        tracing::error!("Failed to queue action to add mod");
+                    }
                 }
+
                 Handled::Yes
             }
             cmd if cmd.is(ACTION_START_SAVE_SETTINGS) => {

crates/dtmm/src/util/log.rs

@@ -1,3 +1,4 @@
+use clap::ValueEnum;
 use tokio::sync::mpsc::UnboundedSender;
 use tracing_error::ErrorLayer;
 use tracing_subscriber::filter::FilterFn;
@@ -7,6 +8,28 @@ use tracing_subscriber::layer::SubscriberExt;
 use tracing_subscriber::prelude::*;
 use tracing_subscriber::EnvFilter;
 
+#[derive(Clone, Copy, ValueEnum)]
+pub enum LogLevel {
+    Trace,
+    Debug,
+    Info,
+    Warn,
+    Error,
+}
+
+impl From<LogLevel> for EnvFilter {
+    fn from(level: LogLevel) -> Self {
+        let filter = match level {
+            LogLevel::Trace => "error,dtmm=trace,sdk=trace",
+            LogLevel::Debug => "error,dtmm=debug,sdk=debug",
+            LogLevel::Info => "error,dtmm=info",
+            LogLevel::Warn => "error,dtmm=warn",
+            LogLevel::Error => "error",
+        };
+        EnvFilter::new(filter)
+    }
+}
+
 pub struct ChannelWriter {
     tx: UnboundedSender<Vec<u8>>,
 }
@@ -32,8 +55,10 @@ impl std::io::Write for ChannelWriter {
     }
 }
 
-pub fn create_tracing_subscriber(tx: UnboundedSender<Vec<u8>>) {
-    let env_layer = if cfg!(debug_assertions) {
+pub fn create_tracing_subscriber(tx: UnboundedSender<Vec<u8>>, level: Option<LogLevel>) {
+    let env_layer = if let Some(level) = level {
+        EnvFilter::from(level)
+    } else if cfg!(debug_assertions) {
         EnvFilter::try_from_default_env().unwrap_or_else(|_| EnvFilter::new("info"))
     } else {
         EnvFilter::new("error,dtmm=info")