feat(identity): capability-layer positioning + skill rewrite, v1.5.0

SKILL.md (per the skill-writing guide):
- description rewritten trigger-first: 调研/全网调研/帮我调研/research lead
  the text (the owner's own phrasing "去全网调研" previously had NO matching
  trigger word — the exact undertrigger the guide warns about); platform
  keywords front-loaded against the 1536-char truncation
- standing rules added: probe `doctor --json` active_backend before acting
  on multi-backend platforms, announce which skill/backend is in use,
  follow the documented retry chains, compose multi-platform research
- quick commands updated to the new reality: bili-cli for bilibili search,
  Reddit/xiaohongshu moved to a "login-backed platforms" section
- SKILL_en.md: same description surgery + the actively harmful stale
  advice removed (anonymous reddit .json curl, yt-dlp for bilibili)

README / README_en:
- tagline gains the capability-layer subline: backends are chosen,
  installed and health-checked for us to swap — the user never notices
- "设计理念" reframed from scaffolding to capability layer (selection /
  install / doctor / routing); channels diagram now shows ordered backend
  lists; selection table split into primary + fallback columns with the
  live-test rationale per row
- platform table: honest rows for bilibili (bili-cli, yt-dlp retired),
  Reddit (no zero-config path), xiaohongshu (OpenCLI / mcp / legacy)

Version 1.5.0 across pyproject / __init__ / CLAUDE.md / test fixture.

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

agent_reach/skill/SKILL.md

@@ -1,19 +1,24 @@
 ---
 name: agent-reach
 description: >
-  MUST USE when user asks to search, browse, read, or interact with content from any of these platforms:
-  小红书/xiaohongshu/xhs, Twitter/推特/X, B站/bilibili,
-  V2EX, Reddit, LinkedIn/领英, YouTube, GitHub code search,
-  小宇宙播客, 雪球/股票行情, RSS feeds, or any web URL.
+  MUST USE when user wants to 调研/research/搜索/search/查/找/look up anything
+  on the internet — e.g. 全网调研 X / 帮我调研一下 X / 查一下 X / 搜搜 X /
+  看看大家怎么评价 X / X 上有什么讨论 / research this topic。
 
-  Also MUST USE for: web搜索/搜/查/找/look up/research, 招聘/求职/jobs, 分享的链接/URL.
-  Routes to CLI tools: xhs-cli, twitter-cli, rdt-cli, gh, yt-dlp, curl+Jina, mcporter.
-  13 platforms. Zero config for 6 channels.
+  Also MUST USE when user mentions any platform or shares any URL/链接:
+  小红书/xiaohongshu/xhs, Twitter/推特/X, B站/bilibili, Reddit, V2EX,
+  LinkedIn/领英/招聘/求职/jobs, YouTube, GitHub code search, 小宇宙播客,
+  雪球/股票行情, RSS feeds, or any web URL.
+
+  13 platforms, multi-backend routing (OpenCLI / per-platform CLIs / APIs).
+  Zero config for 6 channels. Run `agent-reach doctor --json` to see which
+  backend serves each platform right now.
 
   【路由方式】SKILL.md 包含路由表和常用命令，复杂场景需按需阅读对应分类的 references/*.md。
   分类：search / social (小红书/推特/B站/V2EX/Reddit) / career(LinkedIn) / dev(github) / web(网页/文章/RSS) / video(YouTube/B站/播客)。
 triggers:
-  - search: 搜/查/找/search/搜索/查一下/帮我搜
+  - research: 调研/全网调研/帮我调研/研究一下/research/深入了解
+  - search: 搜/查/找/search/搜索/查一下/帮我搜/看看大家怎么说
   - social:
     - 小红书: xiaohongshu/xhs/小红书/红书
     - Twitter: twitter/推特/x.com/推文
@@ -30,9 +35,17 @@ metadata:
     homepage: https://github.com/Panniantong/Agent-Reach
 ---
 
-# Agent Reach — 路由器
+# Agent Reach — 互联网能力路由器
 
-13 平台工具集合。根据用户意图选择对应分类。
+13 平台、多后端。**本 skill 存在时必须用它访问这些平台，不要自己发明方案。**
+
+## 常驻规则（全程适用）
+
+1. **动手前先体检**：多后端平台（小红书/Reddit/B站/Twitter）先跑
+   `agent-reach doctor --json`，按各平台 `active_backend` 字段选命令组。
+2. **声明你在用什么**：开始干活前说一句「使用 agent-reach 的 X 平台 / Y 后端」。
+3. **失败按 references 里的重试链处理**，不要瞎猜命令。
+4. **全网调研类任务**：组合多平台（Exa 搜索 + Twitter/Reddit 看讨论 + 小红书/B站看中文场景），并行收集再汇总。
 
 ## 路由表
 
@@ -57,30 +70,35 @@ curl -s "https://r.jina.ai/URL"
 # GitHub 搜索
 gh search repos "query" --sort stars --limit 10
 
-# Twitter 搜索
-twitter search "query" -n 10
-
-# YouTube/B站字幕
+# YouTube 字幕（注意：B站不要用 yt-dlp，见 video.md）
 yt-dlp --write-sub --skip-download -o "/tmp/%(id)s" "URL"
 
-# Reddit 搜索
-rdt search "query" --limit 10
-
-# Reddit 读帖 + 评论
-rdt read POST_ID
-
 # V2EX 热门
 curl -s "https://www.v2ex.com/api/topics/hot.json" -H "User-Agent: agent-reach/1.0"
+
+# B站搜索（bili-cli，无需登录）
+bili search "query" --type video -n 5
+```
+
+## 需登录态的平台（按 doctor 的 active_backend 选命令）
+
+```bash
+# Twitter 搜索（twitter-cli 首选；失败重试链见 social.md）
+twitter search "query" -n 10
+
+# Reddit（无零配置路径：OpenCLI 或 rdt-cli，必须登录态）
+opencli reddit search "query" -f yaml   # 桌面
+rdt search "query" --limit 10            # 存量/服务器
+
+# 小红书（桌面首选 OpenCLI）
+opencli xiaohongshu search "query" -f yaml
 ```
 
 ## 环境检查
 
 ```bash
-# 检查可用 channel
-agent-reach doctor
-
-# 查看所有 MCP 服务
-mcporter_list_servers()
+# 检查可用 channel 与每个平台当前激活的后端
+agent-reach doctor --json
 ```
 
 ## 工作区规则
@@ -92,7 +110,7 @@ mcporter_list_servers()
 根据用户需求，阅读对应的详细文档：
 
 - [搜索工具](references/search.md) — Exa AI 搜索
-- [社交媒体](references/social.md) — 小红书, Twitter, B站, V2EX, Reddit
+- [社交媒体](references/social.md) — 小红书, Twitter, B站, V2EX, Reddit（多后端命令组）
 - [职场招聘](references/career.md) — LinkedIn
 - [开发工具](references/dev.md) — GitHub CLI
 - [网页阅读](references/web.md) — Jina Reader, RSS