feat: add daemon log viewer to web UI

Co-authored-by: aider (gemini/gemini-2.5-pro-preview-05-06) <aider@aider.chat>

src/api.rs

@@ -5,6 +5,7 @@ use chrono::{Local, Timelike};
 use get_if_addrs::get_if_addrs;
 use serde::{Deserialize, Serialize};
 use serde_json;
+use std::collections::VecDeque;
 use std::sync::{Arc, Mutex};
 
 use crate::config::{self, Config};
@@ -33,6 +34,7 @@ struct ApiStatus {
 pub struct AppState {
     pub ltc_state: Arc<Mutex<LtcState>>,
     pub config: Arc<Mutex<Config>>,
+    pub log_buffer: Arc<Mutex<VecDeque<String>>>,
 }
 
 #[get("/api/status")]
@@ -117,6 +119,12 @@ async fn get_config(data: web::Data<AppState>) -> impl Responder {
     HttpResponse::Ok().json(&*config)
 }
 
+#[get("/api/logs")]
+async fn get_logs(data: web::Data<AppState>) -> impl Responder {
+    let logs = data.log_buffer.lock().unwrap();
+    HttpResponse::Ok().json(&*logs)
+}
+
 #[post("/api/config")]
 async fn update_config(
     data: web::Data<AppState>,
@@ -126,23 +134,28 @@ async fn update_config(
     *config = req.into_inner();
 
     if config::save_config("config.yml", &config).is_ok() {
-        eprintln!("🔄 Saved config via API: {:?}", *config);
+        log::info!("🔄 Saved config via API: {:?}", *config);
         HttpResponse::Ok().json(&*config)
     } else {
-        HttpResponse::InternalServerError().json(serde_json::json!({ "status": "error", "message": "Failed to write config.yml" }))
+        log::error!("Failed to write config.yml");
+        HttpResponse::InternalServerError().json(
+            serde_json::json!({ "status": "error", "message": "Failed to write config.yml" }),
+        )
     }
 }
 
 pub async fn start_api_server(
     state: Arc<Mutex<LtcState>>,
     config: Arc<Mutex<Config>>,
+    log_buffer: Arc<Mutex<VecDeque<String>>>,
 ) -> std::io::Result<()> {
     let app_state = web::Data::new(AppState {
         ltc_state: state,
         config: config,
+        log_buffer: log_buffer,
     });
 
-    println!("🚀 Starting API server at http://0.0.0.0:8080");
+    log::info!("🚀 Starting API server at http://0.0.0.0:8080");
 
     HttpServer::new(move || {
         App::new()
@@ -151,6 +164,7 @@ pub async fn start_api_server(
             .service(manual_sync)
             .service(get_config)
             .service(update_config)
+            .service(get_logs)
             // Serve frontend static files
             .service(fs::Files::new("/", "static/").index_file("index.html"))
     })

src/config.rs

@@ -46,7 +46,7 @@ impl Config {
             return Self::default();
         }
         serde_yaml::from_str(&contents).unwrap_or_else(|e| {
-            eprintln!("Failed to parse config, using default: {}", e);
+            log::warn!("Failed to parse config, using default: {}", e);
             Self::default()
         })
     }
@@ -82,7 +82,7 @@ pub fn watch_config(path: &str) -> Arc<Mutex<Config>> {
                     let new_cfg = Config::load(&watch_path_for_cb);
                     let mut cfg = config_for_cb.lock().unwrap();
                     *cfg = new_cfg;
-                    eprintln!("🔄 Reloaded config.yml: {:?}", *cfg);
+                    log::info!("🔄 Reloaded config.yml: {:?}", *cfg);
                 }
             }
         })

src/logger.rs

@@ -0,0 +1,52 @@
+use chrono::Local;
+use log::{LevelFilter, Log, Metadata, Record};
+use std::collections::VecDeque;
+use std::sync::{Arc, Mutex};
+
+const MAX_LOG_ENTRIES: usize = 100;
+
+struct RingBufferLogger {
+    buffer: Arc<Mutex<VecDeque<String>>>,
+}
+
+impl Log for RingBufferLogger {
+    fn enabled(&self, metadata: &Metadata) -> bool {
+        metadata.level() <= LevelFilter::Info
+    }
+
+    fn log(&self, record: &Record) {
+        if self.enabled(record.metadata()) {
+            let msg = format!(
+                "{} [{}] {}",
+                Local::now().format("%Y-%m-%d %H:%M:%S"),
+                record.level(),
+                record.args()
+            );
+
+            // Also print to stderr for console/daemon logging
+            eprintln!("{}", msg);
+
+            let mut buffer = self.buffer.lock().unwrap();
+            if buffer.len() == MAX_LOG_ENTRIES {
+                buffer.pop_front();
+            }
+            buffer.push_back(msg);
+        }
+    }
+
+    fn flush(&self) {}
+}
+
+pub fn setup_logger() -> Arc<Mutex<VecDeque<String>>> {
+    let buffer = Arc::new(Mutex::new(VecDeque::with_capacity(MAX_LOG_ENTRIES)));
+    let logger = RingBufferLogger {
+        buffer: buffer.clone(),
+    };
+
+    // We use `set_boxed_logger` to install our custom logger.
+    // The `log` crate will then route all log messages to it.
+    log::set_boxed_logger(Box::new(logger)).expect("Failed to set logger");
+    log::set_max_level(LevelFilter::Info);
+
+    buffer
+}

src/main.rs

@@ -2,6 +2,7 @@
 
 mod api;
 mod config;
+mod logger;
 mod serial_input;
 mod sync_logic;
 mod system;
@@ -14,7 +15,6 @@ use crate::sync_logic::LtcState;
 use crate::ui::start_ui;
 use clap::Parser;
 use daemonize::Daemonize;
-use env_logger;
 
 use std::{
     fs,
@@ -57,16 +57,18 @@ fn ensure_config() {
     if !p.exists() {
         fs::write(p, DEFAULT_CONFIG.trim())
             .expect("Failed to write default config.yml");
-        eprintln!("⚙️  Emitted default config.yml");
+        log::info!("⚙️  Emitted default config.yml");
     }
 }
 
 #[tokio::main(flavor = "current_thread")]
 async fn main() {
+    // This must be called before any logging statements.
+    let log_buffer = logger::setup_logger();
     let args = Args::parse();
 
     if let Some(Command::Daemon) = &args.command {
-        println!("🚀 Starting daemon...");
+        log::info!("🚀 Starting daemon...");
 
         // Create files for stdout and stderr in the current directory
         let stdout = fs::File::create("daemon.out").expect("Could not create daemon.out");
@@ -81,7 +83,7 @@ async fn main() {
         match daemonize.start() {
             Ok(_) => { /* Process is now daemonized */ }
             Err(e) => {
-                eprintln!("Error daemonizing: {}", e);
+                log::error!("Error daemonizing: {}", e);
                 return; // Exit if daemonization fails
             }
         }
@@ -116,9 +118,9 @@ async fn main() {
 
     // 5️⃣ Spawn UI or setup daemon logging
     if args.command.is_none() {
-        println!("🔧 Watching config.yml...");
-        println!("🚀 Serial thread launched");
-        println!("🖥️ UI thread launched");
+        log::info!("🔧 Watching config.yml...");
+        log::info!("🚀 Serial thread launched");
+        log::info!("🖥️ UI thread launched");
         let ui_state = ltc_state.clone();
         let config_clone = config.clone();
         let port = "/dev/ttyACM0".to_string();
@@ -126,10 +128,8 @@ async fn main() {
             start_ui(ui_state, port, config_clone);
         });
     } else {
-        // In daemon mode, we initialize env_logger.
-        // This will log to stdout, and the systemd service will capture it.
-        // The RUST_LOG env var controls the log level (e.g., RUST_LOG=info).
-        env_logger::init();
+        // In daemon mode, logging is already set up to go to stderr.
+        // The systemd service will capture it.
         log::info!("🚀 Starting TimeTurner daemon...");
     }
 
@@ -141,9 +141,12 @@ async fn main() {
             {
                 let api_state = ltc_state.clone();
                 let config_clone = config.clone();
+                let log_buffer_clone = log_buffer.clone();
                 task::spawn_local(async move {
-                    if let Err(e) = start_api_server(api_state, config_clone).await {
-                        eprintln!("API server error: {}", e);
+                    if let Err(e) =
+                        start_api_server(api_state, config_clone, log_buffer_clone).await
+                    {
+                        log::error!("API server error: {}", e);
                     }
                 });
             }
@@ -154,7 +157,7 @@ async fn main() {
                 std::future::pending::<()>().await;
             } else {
                 // In TUI mode, block on the channel.
-                println!("📡 Main thread entering loop...");
+                log::info!("📡 Main thread entering loop...");
                 let _ = task::spawn_blocking(move || {
                     for _frame in rx {
                         // no-op