feat(bilibili,twitter): yt-dlp exits bilibili; OpenCLI joins both

bilibili:
- live-verified 2026-06: bilibili 412-blocks yt-dlp in every
  configuration (latest version, direct, proxied, warmed cookies) while
  bili-cli works fine without login — so yt-dlp no longer serves this
  channel (it remains the YouTube backend)
- backends = [bili-cli, OpenCLI, B站搜索 API]: bili-cli covers
  search/hot/rank/video-detail/audio, OpenCLI adds subtitles through the
  browser session, the search API is the zero-dependency fallback
- when a broken candidate is bypassed by a working fallback, its
  reinstall prescription is appended to the winning message instead of
  being swallowed
- skill docs (social.md + video.md): "do NOT use yt-dlp for bilibili"
  warning, bili-cli/OpenCLI command groups, curl fallback recipe,
  B站 audio transcription path via `bili audio` + agent-reach transcribe

twitter:
- OpenCLI joins as the middle candidate [twitter-cli, OpenCLI, bird]
- social.md: explicit 4-step search retry chain (retry → upgrade →
  OpenCLI → stable-command detour)

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

agent_reach/skill/references/video.md

@@ -50,35 +50,48 @@ agent-reach transcribe ./local_audio.mp3 -o /tmp/transcript.txt
 > 需要先配置 key：`agent-reach configure groq-key gsk_xxx`（免费，console.groq.com）
 > 或 `agent-reach configure openai-key sk-xxx`。默认 auto 模式：groq 失败自动降级 openai。
 
-## B站 / Bilibili (yt-dlp + bili-cli)
+## B站 / Bilibili（bili-cli 为主，OpenCLI 补字幕）
 
-### 视频元数据 (yt-dlp)
+> ⚠️ **不要用 yt-dlp 读 B站**：B站风控已全面 412 拦截 yt-dlp（实测最新版、直连/代理/带 Cookie 全部无效）。yt-dlp 只用于 YouTube。
+
+### 视频详情/搜索/热门/排行 (bili-cli，只读无需登录)
 
 ```bash
-yt-dlp --dump-json "https://www.bilibili.com/video/BVxxx"
-```
+# 视频详情（标题/UP主/时长/播放互动数据/字幕可用性）
+bili video BVxxx
 
-### 字幕 (yt-dlp)
-
-```bash
-yt-dlp --write-sub --write-auto-sub --sub-lang "zh-Hans,zh,en" --convert-subs vtt --skip-download -o "/tmp/%(id)s" "URL"
-```
-
-### 搜索/热门/排行 (bili-cli)
-
-```bash
 # 搜索视频
 bili search "query" --type video -n 5
 
-# 热门视频
+# 热门视频 / 排行榜
 bili hot -n 10
-
-# 排行榜
 bili rank -n 10
+
+# 下载音频并切分为 ASR-ready WAV（无字幕时配合 agent-reach transcribe 转写）
+bili audio BVxxx
 ```
 
-> **412 风控**: 海外 IP 必须提供 Cookie（`--cookies-from-browser chrome` 或 `--cookies /path/to/cookies.txt`），国内 IP 一般不受影响。
-> **安装 bili-cli**: `pipx install bilibili-cli`，然后 `bili login` 扫码登录。
+### 字幕 (OpenCLI，需要桌面 Chrome)
+
+```bash
+# 字幕逐句带时间轴
+opencli bilibili subtitle BVxxx
+
+# OpenCLI 也能搜索/读视频元数据（备选）
+opencli bilibili search "query" -f yaml
+opencli bilibili video BVxxx -f yaml
+```
+
+### 零配置兜底：搜索 API 直连
+
+```bash
+UA="Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36"
+curl -s -c /tmp/bili_ck.txt -o /dev/null -A "$UA" "https://www.bilibili.com/"
+curl -s -b /tmp/bili_ck.txt -A "$UA" -e "https://www.bilibili.com/" \
+  "https://api.bilibili.com/x/web-interface/search/all/v2?keyword=QUERY&page=1"
+```
+
+> **安装 bili-cli**: `pipx install bilibili-cli`（上游 2026-03 起停更但实测健康；只读场景无需登录，`bili login` 扫码可解锁动态/收藏等个人功能）。
 
 ## 小宇宙播客 / Xiaoyuzhou Podcast
 
@@ -111,6 +124,7 @@ agent-reach doctor
 | 场景 | 推荐工具 |
 |-----|---------|
 | YouTube 字幕 | yt-dlp |
-| B站字幕 | yt-dlp |
+| B站视频详情/搜索 | bili-cli |
+| B站字幕 | opencli bilibili subtitle |
 | 播客转录 | 小宇宙 transcribe.sh |
-| 无字幕音视频 | agent-reach transcribe |
+| 无字幕音视频 | agent-reach transcribe（B站音频先 `bili audio`） |