add quickjs but has bugs

spec/quickjs_runtime.md

@@ -0,0 +1,67 @@
+# Feature Specification: QuickJS Runtime Integration for yt-dlp
+
+## 1. Context & Objective
+`yt-dlp` increasingly relies on a JavaScript runtime to execute complex decryption scripts (e.g., signature extraction) required by YouTube and other platforms. Without a JS runtime, downloads may fail or be throttled.
+The objective is to automatically manage the **QuickJS** runtime binary (download, update, store) alongside the existing `yt-dlp` binary and configure the download process to utilize it via environment variable injection.
+
+## 2. Technical Requirements
+
+### 2.1. Binary Management
+The application must manage the QuickJS binary lifecycle identically to how it currently handles `yt-dlp`.
+
+*   **Source Repository:** [https://github.com/quickjs-ng/quickjs](https://github.com/quickjs-ng/quickjs)
+*   **Storage Location:** The user's AppData `bin` directory (same as `yt-dlp`).
+    *   Windows: `%APPDATA%\StreamCapture\bin\`
+    *   macOS: `~/Library/Application Support/StreamCapture/bin/`
+*   **Unified Naming on Disk:**
+    Regardless of the source filename, the binary must be renamed upon saving to ensure consistent invocation:
+    *   **Windows:** `qjs.exe`
+    *   **macOS:** `qjs`
+
+### 2.2. Download & Update Logic
+*   **Check:** On app launch (or `init_ytdlp`), check if `qjs` exists.
+*   **Download:** If missing, fetch the appropriate asset from the latest GitHub release of `quickjs-ng/quickjs`.
+    *   *Note:* Logic must detect OS/Arch to pick the correct asset (e.g., `windows-x86_64`, `macos-x86_64/arm64`).
+*   **Permissions:** On macOS/Linux, ensure `chmod +x` is applied.
+*   **Update:** When `update_ytdlp` is triggered, also check/redownload the latest `qjs` binary.
+
+### 2.3. Execution & Environment Injection
+To enable `yt-dlp` to find the `qjs` binary without hardcoding absolute paths in the flags (which can be fragile), we will modify the **subprocess environment**.
+
+*   **Command Flag:** Always pass `--js-runtime qjs` to the `yt-dlp` command.
+*   **Environment Modification:**
+    Before spawning the `yt-dlp` child process in Rust, dynamically modify its `PATH` environment variable.
+    *   **Action:** Prepend the absolute path of the application's `bin` directory to the system `PATH`.
+    *   **Result:** When `yt-dlp` looks for `qjs`, it will find it in the injected `PATH`.
+
+## 3. Implementation Plan
+
+### Step 1: Refactor `src-tauri/src/ytdlp.rs`
+*   Rename file/module to `src-tauri/src/binary_manager.rs` (Optional, or just expand `ytdlp.rs`).
+*   Add constants/functions for QuickJS:
+    *   `get_qjs_binary_name()`
+    *   `download_qjs()`: Similar logic to `download_ytdlp` but parsing QuickJS release assets.
+
+### Step 2: Update `src-tauri/src/commands.rs`
+*   Update `init_ytdlp` to initialize **both** binaries.
+*   Update `update_ytdlp` to update **both** binaries.
+
+### Step 3: Update `src-tauri/src/downloader.rs`
+*   In `download_video` and `fetch_metadata`:
+    1.  Resolve the absolute path to the `bin` directory.
+    2.  Read the current system `PATH`.
+    3.  Construct a new `PATH` string: `bin_dir + delimiter + system_path`.
+    4.  Configure the `Command`:
+        ```rust
+        Command::new(...)
+            .env("PATH", new_path)
+            .arg("--js-runtime")
+            .arg("qjs")
+            ...
+        ```
+
+## 4. Acceptance Criteria
+1.  **File Existence:** `qjs.exe` (Win) or `qjs` (Mac) appears in the `bin` folder after app startup.
+2.  **Process Execution:** The logs show `yt-dlp` running successfully.
+3.  **Verification:** If a specific video requires JS interpretation (often indicated by slow downloads or errors without JS), it proceeds smoothly.
+4.  **Clean Logs:** No "PhantomJS not found" or "JS engine not found" warnings in the logs.