add logging

spec/logging_feature.md

@@ -0,0 +1,58 @@
+# Feature Request: Real-time Logging & UI Refinement
+
+## 1. Context & Objective
+Users currently experience download failures without sufficient context or error details, making troubleshooting difficult.
+The objective is to introduce a dedicated **Logs System** within the application to capture, display, and persist detailed execution logs from the `yt-dlp` process.
+Additionally, the application's sidebar layout requires balancing for better UX.
+
+## 2. Requirements
+
+### 2.1. Backend (Rust) - Logging Infrastructure
+*   **Stream Capture**: The `downloader` module must capture both `STDOUT` (progress) and `STDERR` (errors/warnings) from the `yt-dlp` process.
+*   **Event Emission**: Emit a new Tauri event `download-log` to the frontend in real-time.
+    *   Payload: `{ id: String, message: String, level: 'info' | 'error' | 'debug' }`
+*   **Persistence (Optional but Recommended)**: Ideally, write logs to a local file (e.g., `logs/{date}.log` or `logs/{task_id}.log`) for post-mortem analysis. *For this iteration, real-time event emission is priority.*
+
+### 2.2. Frontend - Logs View
+*   **New Route**: `/logs`
+*   **UI Layout**:
+    *   A dedicated **Logs Tab** in the main navigation.
+    *   A console-like view displaying a stream of log messages.
+    *   Filters: Filter by "Task ID" or "Level" (Error/Info).
+    *   **Real-time**: The view must update automatically as new log events arrive.
+    *   **Detail**: Failed downloads must show the specific error message returned by `yt-dlp` (e.g., "Sign in required", "Video unavailable").
+
+### 2.3. UI/UX - Sidebar Refactoring
+*   **Reordering**:
+    *   **Top Section**: Home (Downloader), History.
+    *   **Bottom Section**: Logs, Settings.
+*   **Removal**: Remove the "Version Number" text from the bottom of the sidebar (it can be moved to the Settings page if needed, or just removed as requested).
+
+## 3. Implementation Steps
+
+### Step 1: Rust Backend Updates
+*   Modify `src-tauri/src/downloader.rs`:
+    *   Update `download_video` to spawn the process with `Stdio::piped()` for both stdout and stderr.
+    *   Use `tokio::select!` or separate tasks to read both streams concurrently.
+    *   Emit `download-log` events for every line read.
+    *   Ensure the final error message (if exit code != 0) is explicitly captured and returned/logged.
+
+### Step 2: Frontend Store & Logic
+*   Create `src/stores/logs.ts`:
+    *   State: `logs: LogEntry[]`.
+    *   Action: `addLog(entry)`.
+    *   Listener: Listen for `download-log` events globally.
+
+### Step 3: Frontend UI
+*   Create `src/views/Logs.vue`:
+    *   Display logs in a scrollable container.
+    *   Style error logs in red, info in gray/white.
+*   Update `src/App.vue`:
+    *   Add the `FileText` (or similar) icon for Logs.
+    *   Refactor the sidebar Flexbox layout to push Logs and Settings to the bottom.
+    *   Remove the version footer.
+*   Update `src/router/index.ts` to include the new route.
+
+## 4. Success Criteria
+*   When a download fails, the user can go to the "Logs" tab and see the exact error output from `yt-dlp`.
+*   The sidebar looks balanced with navigation items split between top and bottom.