Add debug logging to file and fix blank startup screen

- Added write_log Tauri command that writes to frontend.log in app data dir
- App.svelte now logs each startup step (Tauri import, sidecar check, launch)
- Startup overlays use inline styles as fallback so they're visible even if
  CSS variables fail to load
- Debug status shown on the checking/connecting screens
- Rust side logs startup info to app.log (resource dir, data dir)

Log files location: %APPDATA%/net.anhonesthost.local-transcription/ (Windows)
or ~/Library/Application Support/net.anhonesthost.local-transcription/ (macOS)

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

src-tauri/Cargo.lock

@@ -316,8 +316,10 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "c673075a2e0e5f4a1dde27ce9dee1ea4558c7ffe648f576438a20ca1d2acc4b0"
 dependencies = [
  "iana-time-zone",
+ "js-sys",
  "num-traits",
  "serde",
+ "wasm-bindgen",
  "windows-link 0.2.1",
 ]
 
@@ -1879,9 +1881,10 @@ checksum = "92daf443525c4cce67b150400bc2316076100ce0b3686209eb8cf3c31612e6f0"
 
 [[package]]
 name = "local-transcription"
-version = "1.4.3"
+version = "1.4.5"
 dependencies = [
  "bytes",
+ "chrono",
  "futures-util",
  "reqwest 0.12.28",
  "serde",

src-tauri/Cargo.toml

@@ -24,3 +24,4 @@ futures-util = "0.3"
 zip = { version = "2", default-features = false, features = ["deflate"] }
 bytes = "1"
 tokio = { version = "1", features = ["full"] }
+chrono = "0.4"

src-tauri/src/lib.rs

@@ -3,6 +3,26 @@ mod sidecar;
 use std::sync::Mutex;
 use tauri::Manager;
 
+/// App log directory, set during setup.
+static LOG_DIR: std::sync::OnceLock<std::path::PathBuf> = std::sync::OnceLock::new();
+
+/// Write a log message to the app's log file (for debugging).
+#[tauri::command]
+fn write_log(message: String) {
+    if let Some(log_dir) = LOG_DIR.get() {
+        let log_path = log_dir.join("frontend.log");
+        use std::io::Write;
+        if let Ok(mut f) = std::fs::OpenOptions::new()
+            .create(true)
+            .append(true)
+            .open(&log_path)
+        {
+            let _ = writeln!(f, "[{}] {}", chrono::Local::now().format("%H:%M:%S%.3f"), message);
+        }
+    }
+    eprintln!("[frontend] {}", message);
+}
+
 #[cfg_attr(mobile, tauri::mobile_entry_point)]
 pub fn run() {
     tauri::Builder::default()
@@ -22,9 +42,22 @@ pub fn run() {
                 .app_data_dir()
                 .expect("failed to resolve app data dir");
 
-            // Ensure the data directory exists
             std::fs::create_dir_all(&data_dir).expect("failed to create app data dir");
 
+            // Set up logging
+            LOG_DIR.set(data_dir.clone()).ok();
+            let log_path = data_dir.join("app.log");
+            if let Ok(mut f) = std::fs::OpenOptions::new()
+                .create(true)
+                .append(true)
+                .open(&log_path)
+            {
+                use std::io::Write;
+                let _ = writeln!(f, "\n=== App started at {} ===", chrono::Local::now());
+                let _ = writeln!(f, "Resource dir: {}", resource_dir.display());
+                let _ = writeln!(f, "Data dir: {}", data_dir.display());
+            }
+
             sidecar::init_dirs(resource_dir, data_dir);
             Ok(())
         })
@@ -35,6 +68,7 @@ pub fn run() {
             sidecar::get_sidecar_port,
             sidecar::start_sidecar,
             sidecar::stop_sidecar,
+            write_log,
         ])
         .run(tauri::generate_context!())
         .expect("error while running tauri application");

src/App.svelte

@@ -13,6 +13,7 @@
 
   let showSettings = $state(false);
   let sidecarState = $state<SidecarState>("checking");
+  let debugLog = $state("");
 
   let obsDisplayUrl = $derived(backendStore.obsUrl);
   let syncDisplayUrl = $derived(backendStore.syncUrl);
@@ -27,13 +28,25 @@
     showSettings = false;
   }
 
+  let tauriInvoke: ((cmd: string, args?: Record<string, unknown>) => Promise<unknown>) | null = null;
+
+  function log(msg: string) {
+    console.log(`[App] ${msg}`);
+    debugLog = msg;
+    // Also write to file via Tauri if available
+    tauriInvoke?.("write_log", { message: msg });
+  }
+
   async function checkAndLaunchSidecar() {
     try {
+      log("Importing Tauri API...");
       const { invoke } = await import("@tauri-apps/api/core");
+      tauriInvoke = invoke;
 
-      // Check if sidecar is installed
+      log("Checking if sidecar is installed...");
       sidecarState = "checking";
       const installed = await invoke<boolean>("check_sidecar");
+      log(`Sidecar installed: ${installed}`);
 
       if (!installed) {
         sidecarState = "needs_setup";
@@ -41,9 +54,10 @@
       }
 
       await launchSidecar();
-    } catch {
+    } catch (err) {
       // Not running in Tauri (browser dev mode) - skip sidecar check
       // and connect directly to localhost:8081
+      log(`Tauri not available (${err}), using dev mode`);
       sidecarState = "starting";
       backendStore.setPort(8081);
       backendStore.connect();
@@ -55,15 +69,19 @@
     try {
       const { invoke } = await import("@tauri-apps/api/core");
 
+      log("Starting sidecar...");
       sidecarState = "starting";
       await invoke("start_sidecar");
 
+      log("Getting sidecar port...");
       const port = await invoke<number>("get_sidecar_port");
+      log(`Sidecar ready on port ${port}`);
       backendStore.setPort(port);
       backendStore.connect();
       configStore.loadConfig();
-    } catch {
+    } catch (err) {
       // If sidecar launch fails, still try connecting to default port
+      log(`Sidecar launch failed: ${err}, trying default port`);
       sidecarState = "starting";
       backendStore.connect();
       configStore.loadConfig();
@@ -84,13 +102,16 @@
 </script>
 
 {#if sidecarState === "checking"}
-  <div class="connecting-overlay">
+  <div class="connecting-overlay" style="background:#1e1e1e;color:#e0e0e0;display:flex;align-items:center;justify-content:center;height:100%;width:100%;">
-    <div class="connecting-content">
+    <div class="connecting-content" style="text-align:center;">
       <div class="connecting-icon">
         <div class="spinner"></div>
       </div>
-      <h2>Local Transcription</h2>
+      <h2 style="font-size:20px;margin:16px 0 8px;">Local Transcription</h2>
-      <p>Checking setup...</p>
+      <p style="color:#a0a0a0;font-size:14px;">Checking setup...</p>
+      {#if debugLog}
+        <p style="color:#707070;font-size:11px;margin-top:12px;">{debugLog}</p>
+      {/if}
     </div>
   </div>
 
@@ -98,8 +119,8 @@
   <SidecarSetup onComplete={onSidecarReady} />
 
 {:else if !isConnected}
-  <div class="connecting-overlay">
+  <div class="connecting-overlay" style="background:#1e1e1e;color:#e0e0e0;display:flex;align-items:center;justify-content:center;height:100%;width:100%;">
-    <div class="connecting-content">
+    <div class="connecting-content" style="text-align:center;">
       <div class="connecting-icon">
         {#if connectionState === "error"}
           <svg width="48" height="48" viewBox="0 0 24 24" fill="none" stroke="#e74c3c" stroke-width="2">
@@ -111,13 +132,16 @@
           <div class="spinner"></div>
         {/if}
       </div>
-      <h2>Local Transcription</h2>
+      <h2 style="font-size:20px;margin:16px 0 8px;">Local Transcription</h2>
       {#if connectionState === "error"}
-        <p>Cannot connect to backend</p>
+        <p style="color:#a0a0a0;">Cannot connect to backend</p>
         <p class="hint">Make sure the Python backend is running:<br>
           <code>uv run python -m backend.main_headless</code></p>
       {:else}
-        <p>Connecting to backend...</p>
+        <p style="color:#a0a0a0;">Connecting to backend...</p>
+      {/if}
+      {#if debugLog}
+        <p style="color:#707070;font-size:11px;margin-top:12px;">{debugLog}</p>
       {/if}
     </div>
   </div>