feat: add Weibo channel via mcp-server-weibo (addresses #75)

[AICodeLion]

Summary

Adds a Weibo (微博) channel that integrates qinyuanpei/mcp-server-weibo (34+ ⭐, MIT license, 10 tools) via mcporter.

This addresses #75 — a user requested Weibo support for monitoring bloggers' new posts.

Why a dedicated channel?

Weibo's mobile API (m.weibo.cn) is not accessible via curl or Jina Reader:

• Without cookies: returns HTTP 302 (redirect to visitor passport) from foreign IPs, or HTTP 432 from datacenter IPs
• The visitor passport flow involves a multi-step JavaScript-based cookie acquisition process (genvisitor2 → crossdomain → set 9 cookies)
• The SUB cookie obtained through this flow is valid for 1 year
• Once cookies are obtained, all API endpoints work reliably without proxy

The upstream MCP server (mcp-server-weibo) wraps this complexity and provides 10 structured tools.

Changes

3 files, +57 lines:

File	Change
agent_reach/channels/weibo.py	New WeiboChannel (54 lines)
agent_reach/channels/__init__.py	Register WeiboChannel
tests/test_channel_contracts.py	Add weibo URL sample

Channel design

• can_handle(): matches weibo.com and weibo.cn (including subdomains like m.weibo.cn, s.weibo.com)
• check(): two-layer detection:
  1. mcporter config list — verify MCP server is configured
  2. mcporter list weibo — verify tools load correctly (lightweight, no live API call)
• tier=1: requires installing mcp-server-weibo but no paid API key
• Style: follows existing patterns (same "domain" in d matching as other channels, same subprocess.run + mcporter pattern as XiaoHongShu/Douyin/BossZhipin)

Upstream MCP server capabilities

mcp-server-weibo v1.0.7 provides 10 tools:

Tool	Description
search_users	Search users by keyword
get_profile	Get user profile (name, bio, follower count, verification)
get_feeds	Get user's posts with pagination
get_hot_feeds	Get user's popular posts
get_trendings	Get real-time trending topics (热搜)
search_content	Search posts by keyword
search_topics	Search hashtag topics with read/discussion counts
get_comments	Get comments for a specific post
get_followers	Get user's following list
get_fans	Get user's fan list

Install: uvx mcp-server-weibo or pip install mcp-server-weibo

Test results

Unit tests: 9/9 passed

tests/test_channel_contracts.py::test_channel_registry_contract PASSED
tests/test_channel_contracts.py::test_channel_check_contract_with_minimal_runtime PASSED
tests/test_channel_contracts.py::test_channel_can_handle_contract PASSED
tests/test_channels.py (3 tests) PASSED
tests/test_core.py (3 tests) PASSED

E2E tool tests: 10/10 passed

All 10 MCP tools verified with live Weibo API:

• search_users: ✅ (found @雷军, @人民日报)
• get_profile: ✅ (11 fields complete)
• get_feeds: ✅ (with engagement metrics, location, media)
• get_hot_feeds: ✅
• get_trendings: ✅ (returns up to 53 items)
• search_content: ✅ (includes pic thumbnails + video stream URLs)
• search_topics: ✅ (includes read count + discussion count)
• get_comments: ✅
• get_followers/get_fans: ✅

Stability test: 8/8 consecutive calls, avg 1.9s/call

Edge cases tested

Case	Result
Non-existent uid	MCP returns error (upstream issue)
uid=0	MCP returns error (upstream issue)
Empty search	Returns empty array ✅
Emoji search (🐻)	Works ✅
Japanese text search	Works ✅
Deactivated account	Returns empty array ✅
limit=100 (over max)	Returns 53 (actual max) ✅

User flow verified

agent-reach doctor  →  "-- 微博: mcporter 已装但微博 MCP 未配置"
    ↓ mcporter config add weibo --command 'uvx mcp-server-weibo'
agent-reach doctor  →  "-- 微博: MCP 已配置但工具加载失败" (if no cookie)
    ↓ configure WEIBO_COOKIE env
agent-reach doctor  →  "✅ 微博: 完整可用（热搜、搜索、用户动态、评论）"

Known issues in upstream MCP server

These are bugs in mcp-server-weibo, not in this PR:

1. search_users() has debug print(result) on line 156 that corrupts MCP stdio transport — causes mcporter to hang. Workaround: remove the print statement. (Will file upstream issue.)
2. get_comments() omits like_count field — the raw API returns it but the data mapping drops it. Hot comments require the hotflow endpoint which isn't exposed.
3. No error handling for invalid uid — throws KeyError: 'userInfo' instead of returning empty.

Cookie notes for overseas users

The MCP server supports WEIBO_COOKIE env var. For servers outside mainland China:

• Weibo's mobile API requires a visitor cookie obtained via the visitor.passport.weibo.cn flow
• The SUB cookie alone is sufficient and valid for 1 year
• Chinese users likely won't need this step (direct access works from domestic IPs)