fix: YouTube requires JS runtime — auto-configure Node.js in install

yt-dlp now requires an external JS runtime (deno or Node.js) for YouTube.
Since agent-reach already installs Node.js, we configure yt-dlp to use it:

1. cli.py: install writes '--js-runtimes node' to ~/.config/yt-dlp/config
2. youtube.py: doctor checks JS runtime availability and config
3. SKILL.md: updated YouTube section with accurate troubleshooting

Bilibili note: 412 errors are IP-based (needs proxy), not cookie-related.

Fixes #47

agent_reach/channels/youtube.py

@@ -1,6 +1,7 @@
 # -*- coding: utf-8 -*-
-"""YouTube — check if yt-dlp is available."""
+"""YouTube — check if yt-dlp is available with JS runtime."""
 
+import os
 import shutil
 from .base import Channel
 
@@ -17,6 +18,23 @@ class YouTubeChannel(Channel):
         return "youtube.com" in d or "youtu.be" in d
 
     def check(self, config=None):
-        if shutil.which("yt-dlp"):
-            return "ok", "可提取视频信息和字幕"
-        return "off", "yt-dlp 未安装。安装：pip install yt-dlp"
+        if not shutil.which("yt-dlp"):
+            return "off", "yt-dlp 未安装。安装：pip install yt-dlp"
+        # Check JS runtime
+        has_js = shutil.which("deno") or shutil.which("node")
+        if not has_js:
+            return "warn", (
+                "yt-dlp 已安装但缺少 JS runtime（YouTube 必须）。\n"
+                "  安装 Node.js 或 deno，然后运行：agent-reach install"
+            )
+        # Check yt-dlp config for --js-runtimes
+        ytdlp_config = os.path.expanduser("~/.config/yt-dlp/config")
+        has_deno = shutil.which("deno")
+        if not has_deno and os.path.exists(ytdlp_config):
+            with open(ytdlp_config, "r") as f:
+                if "--js-runtimes" not in f.read():
+                    return "warn", (
+                        "yt-dlp 已安装但未配置 JS runtime。运行：\n"
+                        "  mkdir -p ~/.config/yt-dlp && echo '--js-runtimes node' >> ~/.config/yt-dlp/config"
+                    )
+        return "ok", "可提取视频信息和字幕"

agent_reach/cli.py

@@ -419,6 +419,25 @@ def _install_system_deps():
             except Exception:
                 print("  ⬜ undici install failed (optional — xreach may not work behind proxies)")
 
+    # ── yt-dlp JS runtime config (YouTube requires external JS runtime) ──
+    if shutil.which("node"):
+        ytdlp_config_dir = os.path.expanduser("~/.config/yt-dlp")
+        ytdlp_config = os.path.join(ytdlp_config_dir, "config")
+        needs_config = True
+        if os.path.exists(ytdlp_config):
+            with open(ytdlp_config, "r") as f:
+                if "--js-runtimes" in f.read():
+                    needs_config = False
+                    print("  ✅ yt-dlp JS runtime already configured")
+        if needs_config:
+            try:
+                os.makedirs(ytdlp_config_dir, exist_ok=True)
+                with open(ytdlp_config, "a") as f:
+                    f.write("--js-runtimes node\n")
+                print("  ✅ yt-dlp configured to use Node.js as JS runtime (YouTube)")
+            except Exception:
+                print("  ⬜ Could not configure yt-dlp JS runtime (YouTube may not work)")
+
 
 def _install_system_deps_safe():
     """Safe mode: check what's installed, print instructions for what's missing."""

agent_reach/skill/SKILL.md

@@ -93,7 +93,8 @@ xreach tweets @username --json -n 20
 
 ### YouTube (yt-dlp)
 
-> ⚠️ 服务器 IP 可能触发 YouTube 反爬（"Sign in to confirm you're not a bot"）。遇到时加 `--cookies-from-browser chrome` 或通过代理。
+> ⚠️ yt-dlp 需要 JS runtime 才能下载 YouTube。`agent-reach install` 会自动配置 Node.js 作为 runtime。
+> 如果遇到 "Sign in to confirm you're not a bot"，是 IP 被 YouTube 反爬，换代理或加 cookies。
 
 ```bash
 # Get video metadata
@@ -106,8 +107,8 @@ yt-dlp --write-sub --write-auto-sub --sub-lang "zh-Hans,zh,en" --skip-download -
 # Search (yt-dlp ytsearch)
 yt-dlp --dump-json "ytsearch5:query"
 
-# If blocked ("Sign in to confirm you're not a bot"):
-yt-dlp --cookies-from-browser chrome --dump-json "URL"
+# If "no JS runtime" warning: ensure Node.js is installed, then run:
+#   mkdir -p ~/.config/yt-dlp && echo "--js-runtimes node" >> ~/.config/yt-dlp/config
 ```
 
 ### Bilibili (yt-dlp)