Channel Selection — Group-First Algorithm

Runtime AI calls this after run_clarify and before run_channel. Produces a ranked list of leaf channels to invoke, using the progressive-disclosure structure from autosearch:router + 14 group index files.

Why Group-First

Flat ranking across 41 channels means reading 41 SKILL.md bodies and scoring each. Group-first reduces the decision to:

1. Pick 1-3 groups (from the 14 group index descriptions — short, already cached).
2. Within picked groups, pick 3-8 leaf channels (leaf metadata is short and already in each group index).

Token savings: ~80% over flat-rank. Latency savings: sub-second at Standard tier vs. ~5s at Best tier for 41-way scoring.

Input

input:
  query: str                          # user's research question
  clarify_result:                     # from run_clarify
    mode: "fast" | "deep" | "comprehensive"
    query_type: str
    rubrics: list[str]
    channel_priority: list[str]        # clarifier's hint
    channel_skip: list[str]            # clarifier's anti-hint
  scope:                               # optional
    languages: "all" | "en_only" | "zh_only" | "mixed"
    recency: "any" | "7d" | "30d" | "90d"
    budget:
      max_channels: int                # hard cap, default 8
      max_groups: int                  # hard cap, default 3
      max_cost_usd: float | null

Algorithm

Stage 1 — Group Selection (≤ 3 groups)

Score each of the 14 groups against the query + rubrics:

Pick top 3 groups with score ≥ 0.4. If fewer than 3 meet threshold, pick just those; if zero, fall back to channels-generic-web.

Apply hard filters:

• Skip any group containing only channels in clarify.channel_skip.
• Skip channels-social-career, channels-market-product, etc. if they don't match domain.
• Skip channels-chinese-ugc + channels-cn-tech if scope.languages == "en_only".
• Skip channels-community-en if scope.languages == "zh_only".

Stage 2 — Leaf Selection (≤ 8 channels across picked groups)

Within each picked group, score each leaf skill:

Pick top 3-8 leaves total across all picked groups. Hard caps from scope.budget apply.

Boss-Rule Enforcements

• Chinese-native guard: if query is Chinese (detected by any Unicode CJK char in query), the output MUST include at least 2 channels from channels-chinese-ugc or channels-cn-tech regardless of historical yield. Boss rule in feedback_autosearch-chinese-channels.
• Channel-quality-not-reduction: never dropout a full group just because historical yield was zero on one past session. Skill requires ≥ 3 consecutive session-level empty yields before demoting.

Output

output:
  groups:                              # stage-1 result
    - name: "channels-chinese-ugc"
      score: 0.82
      rationale: "query mentions 小红书 + clarifier priority includes xiaohongshu"
    - name: "channels-video-audio"
      score: 0.61
      rationale: "xiaoyuzhou podcast mentioned"
  channels:                            # stage-2 result, ranked
    - name: "search-xiaohongshu"
      group: "channels-chinese-ugc"
      score: 0.88
      model_tier: "Fast"
      auth: "paid (TIKHUB_API_KEY set)"
      rationale: "clarifier priority + query-match + auth available"
    - name: "search-xiaoyuzhou"
      group: "channels-video-audio"
      score: 0.74
      model_tier: "Fast"
      auth: "free"
      rationale: "query mentions podcast + scenario match"
    # ... 1-6 more
  chinese_native_quota_met: true
  skipped_groups: ["channels-social-career"]       # why-skipped log
  skipped_channels: ["search-linkedin"]
  elapsed_ms: 140

Invocation Pattern (runtime AI)

# Call order in a research session
clarify = run_clarify(query, mode_hint="fast")
selection = channel_selection(
    query=query,
    clarify_result=clarify,
    scope={"languages": "mixed", "recency": "30d", "budget": {"max_channels": 6}},
)

# Fan out to picked channels
evidence = []
for leaf in selection.channels[:6]:
    resp = run_channel(leaf.name, query, k=10)
    if resp.ok:
        evidence.extend(resp.evidence)

# Runtime AI synthesizes from evidence

When This Skill Is Used

• Any research task that would otherwise require reading 10+ channel SKILL.md files.
• Fan-out planning before parallel run_channel calls.
• Teaching the runtime AI when channel_priority from run_clarify should / shouldn't override the group-first algorithm.

When NOT

• Single-channel queries ("give me the top B站 video on X") — call run_channel("bilibili", query) directly.
• User explicitly names the channels — respect the user's choice; don't re-rank.

Cost

Standard-tier LLM call (one pass, ~5s, ~1K tokens in + ~500 out) or can be degraded to Fast-tier with 90% accuracy on simple queries.

MCP Tool Usage

Use the select_channels_tool MCP tool directly instead of executing this algorithm manually:

select_channels_tool(
  query="小红书有没有人用 Cursor 做编程",
  channel_priority=["xiaohongshu", "zhihu"],   # from run_clarify output
  channel_skip=[],
  mode="fast"
)

Returns {groups: ["channels-chinese-ugc"], channels: ["xiaohongshu", "zhihu", "bilibili"], rationale: "..."}. Pass channels directly to run_channel or delegate_subtask.

Relationship to Other Skills

• Reads → autosearch:router + 14 group index SKILL.md files (L1 progressive disclosure).
• Reads → per-leaf experience.md digests for boost scoring.
• Fed by → run_clarify output.
• Feeds → run_channel fan-out.
• Does NOT replace run_clarify — they're sequential, not alternatives.

Quality Bar

• Evidence items have non-empty title and url.
• No crash on empty or malformed API response.
• Source channel field matches the channel name.