做什么（One-liner）

Porter 5+1 Forces 启发式实现：从 yfinance 财报 proxy signals 派生 6 力量化分 + 3 competitive advantages，产出 0-100 C 分。BLCV 综合评分 C 维输入。

怎么用

Canvas 拖 blcv_compete_v1，填 symbol（必填）+ 可选 peers list。无 peers 时 peer_comparison 为 null；有 peers 时（<=5）逐个 yfinance fetch 做 gross_margin 对比。

核心公式

Porter 5+1 forces (0-1 scale):

• rivalry ← margin_stability heuristic
• threat_new_entrants ← market_cap bucket + growth
• threat_substitutes ← revenue growth deceleration
• buyer_power ← COGS/Revenue 趋势 slope
• supplier_power ← COGS/Revenue 水平
• complementary_power ← (high margin + high growth) heuristic

Competitive advantages (3 fixed):

• market_position: mega_cap_leader / large_cap / mid_cap / small_cap / unknown
• consumer_loyalty: (margin_stab + revenue_stab) / 2
• switching_cost: high / medium / low (based on stability + loyalty)

Scoring:

porter_score    = max(0, 1 - avg_5_threats) + complementary × 0.1
advantage_score = loyalty × 0.4 + switching_weight × 0.3 + market_pos_weight × 0.3
c_score         = (porter_score + advantage_score) / 2 × 100

假设与适用场景

假设：proxy signals (margin → rivalry, COGS → buyer/supplier power) 合理；market_cap USD 阈值；5 年稳态 margin data。

适用：美股 mega-cap / large-cap，成熟行业，长期持有候选的竞争格局评估。

不适用：严格 Porter 分析、非美、快速迭代行业、真正的 multi-peer comparative。

输入 / 输出契约

{symbol: str, peers: list[str] | None} → {symbol, name, porter_forces{6 keys}, porter_evidence[], competitive_advantages[3], c_score, peer_comparison | null, logic_lineage}。

6 Porter 力 + 3 advantages 固定 schema，golden 锁定。

已知局限

1. Proxy-based heuristic 非 canonical Porter（rivalry ← margin_stability 等 mapping 未学术 validated）
2. threat_new_entrants / threat_substitutes 的 proxy 较弱（主要靠 market_cap + growth deceleration）
3. Market position 阈值 500B/100B/10B USD hardcoded
4. Switching cost 3-way discrete（缺 gradient）
5. 50/50 porter vs advantage 权重未做 sensitivity
6. peer_comparison 启用时无 cache —— 注意 yfinance quota
7. 不对比 industry baseline（跨行业 c_score 的 mechanically 可比但 semantically dubious）

参考文献

Porter (1979, 2008) HBR Five Forces 原始 + Brandenburger-Nalebuff (1996) Co-opetition（第 6 力）+ Greenwald-Kahn (2005) Competition Demystified。详见 frontmatter。

Golden Test

tests/golden/fixtures/tier2/blcv_compete/，yfinance-snapshot integration regression (peers=None 路径)，1e-6 tolerance。7 tests：

• matches_snapshot — 全 output 深比对
• c_score_in_0_100_range — 范围 contract
• determinism — 5 reruns byte-identical
• porter_forces_has_six — 6 forces 固定 keys
• advantages_has_three_fixed — 3 advantages 固定 dims
• peers_none_skips_peer_comparison — peers=None → peer_comparison null
• porter_forces_in_0_1_range — 全 6 力 ∈ [0, 1] numeric contract

Peer-enabled 路径未测试（future work：多 symbol snapshot 基础设施）。

Changelog

• 1.0.0 (2026-04-20) — 首次 Active（Tier 2 batch 3, yfinance snapshot regression）