新功能：个性化推荐算法

server/app/features/personalized_reco/rerank_freqcap/rerank.py

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+from __future__ import annotations
+
+from typing import Any, Iterable, Optional
+
+from app.features.personalized_reco.rerank_freqcap.defaults import get_default_config
+from app.features.personalized_reco.rerank_freqcap.types import RerankConfig, RerankMeta, RerankResult, ScoredCandidate, Scene
+from app.features.personalized_reco.rerank_freqcap.utils import as_finite_float, build_tags, clamp, jaccard, normalize_int_id_set
+
+
+def _sort_by_score_desc(cands: list[ScoredCandidate]) -> list[ScoredCandidate]:
+    return sorted(cands, key=lambda x: as_finite_float(x.final_score, default=float("-inf")), reverse=True)
+
+
+def _dedup_by_seen_ids(
+    cands: list[ScoredCandidate],
+    *,
+    seen_ids: set[int],
+) -> tuple[list[ScoredCandidate], int]:
+    kept: list[ScoredCandidate] = []
+    removed = 0
+    for c in cands:
+        if int(c.content_id) in seen_ids:
+            removed += 1
+            continue
+        kept.append(c)
+    return kept, removed
+
+
+def _apply_author_template_freqcap(
+    cands: list[ScoredCandidate],
+    *,
+    recent_author_ids: Optional[Iterable[str]],
+    recent_template_ids: Optional[Iterable[str]],
+) -> tuple[list[ScoredCandidate], dict[str, int], list[str]]:
+    """
+    V1 策略：
+    - 若 recent_*_ids 未提供（None），不执行该维度过滤，但在 meta 记录缺失
+    - 若提供，则执行硬过滤
+    """
+
+    filtered_counts: dict[str, int] = {"author": 0, "template": 0}
+    missing: list[str] = []
+
+    author_set: set[str] | None
+    if recent_author_ids is None:
+        author_set = None
+        missing.append("author")
+    else:
+        author_set = set([a for a in recent_author_ids if a is not None and str(a).strip() != ""])
+
+    template_set: set[str] | None
+    if recent_template_ids is None:
+        template_set = None
+        missing.append("template")
+    else:
+        template_set = set([t for t in recent_template_ids if t is not None and str(t).strip() != ""])
+
+    out: list[ScoredCandidate] = []
+    for c in cands:
+        if author_set is not None and c.author_id and c.author_id in author_set:
+            filtered_counts["author"] += 1
+            continue
+        if template_set is not None and c.template_id and c.template_id in template_set:
+            filtered_counts["template"] += 1
+            continue
+        out.append(c)
+
+    # 只返回真正生效的维度计数（避免 meta 噪音）
+    effective_counts: dict[str, int] = {}
+    if author_set is not None:
+        effective_counts["author"] = int(filtered_counts["author"])
+    if template_set is not None:
+        effective_counts["template"] = int(filtered_counts["template"])
+
+    missing_sorted = sorted(set(missing))
+    return out, effective_counts, missing_sorted
+
+
+def _sim(a: ScoredCandidate, b: ScoredCandidate, *, tags_a: set[str], tags_b: set[str]) -> float:
+    # 离散特征版（V1 推荐），对齐 plan.md
+    if int(a.content_id) == int(b.content_id):
+        return 1.0
+
+    sim = 0.0
+    if a.template_id and b.template_id and a.template_id == b.template_id:
+        sim += 0.6
+    if a.author_id and b.author_id and a.author_id == b.author_id:
+        sim += 0.3
+
+    sim += 0.1 * jaccard(tags_a, tags_b)
+    return clamp(sim, 0.0, 1.0)
+
+
+def _mmr_rerank(
+    *,
+    candidates: list[ScoredCandidate],
+    k: int,
+    lam: float,
+) -> list[ScoredCandidate]:
+    if k <= 0:
+        return []
+
+    if not candidates:
+        return []
+
+    lam_f = clamp(as_finite_float(lam, default=0.7), 0.0, 1.0)
+
+    # 预计算 tags，避免重复构造
+    tags_map: dict[int, set[str]] = {}
+    for c in candidates:
+        tags_map[int(c.content_id)] = build_tags(c)
+
+    remaining = _sort_by_score_desc(list(candidates))
+    selected: list[ScoredCandidate] = []
+
+    # Top1：最高分
+    selected.append(remaining.pop(0))
+
+    while remaining and len(selected) < k:
+        best_idx = 0
+        best_val = float("-inf")
+
+        for idx, c in enumerate(remaining):
+            rel = as_finite_float(c.final_score, default=float("-inf"))
+
+            tags_c = tags_map.get(int(c.content_id), set())
+            max_sim = 0.0
+            for s in selected:
+                tags_s = tags_map.get(int(s.content_id), set())
+                max_sim = max(max_sim, _sim(c, s, tags_a=tags_c, tags_b=tags_s))
+
+            val = lam_f * float(rel) - (1.0 - lam_f) * float(max_sim)
+            if val > best_val:
+                best_val = val
+                best_idx = idx
+
+        selected.append(remaining.pop(best_idx))
+
+    return selected
+
+
+def rerank_and_freqcap(
+    *,
+    scene: Scene,
+    scored_candidates: list[ScoredCandidate],
+    already_recommended_ids: list[Any],
+    touched_or_viewed_ids: list[Any],
+    k: int,
+    config: Optional[RerankConfig] = None,
+    recent_author_ids: Optional[list[str]] = None,
+    recent_template_ids: Optional[list[str]] = None,
+) -> RerankResult:
+    """
+    主入口：对 scored_candidates 做去重/频控/重排，输出最终可下发序列。
+
+    V1 约定：
+    - 冷却窗口“按天”由调用方保证输入集合已经裁剪到窗口内，本模块以“集合代表窗口内历史”为准
+    - Feed 默认只做 dedup + MMR；Push/Widget 做 dedup + freqcap + TopK
+    """
+
+    cfg = config or get_default_config(scene)
+
+    # seen_ids = already_recommended_ids ∪ touched_or_viewed_ids
+    seen_ids = normalize_int_id_set(list(already_recommended_ids) + list(touched_or_viewed_ids))
+
+    # 先按分数降序，保证 Top1 与 TopK 一致
+    base_sorted = _sort_by_score_desc(list(scored_candidates))
+
+    after_dedup, removed_sentence = _dedup_by_seen_ids(base_sorted, seen_ids=seen_ids)
+    candidate_pool_size_after_dedup = len(after_dedup)
+
+    missing_history_fields: list[str] = []
+    freqcap_counts: dict[str, int] = {"sentence": int(removed_sentence)}
+
+    after_freqcap = after_dedup
+
+    # Push/Widget：作者/模板冷却（增强项）
+    if scene in {"push", "widget"}:
+        after_freqcap, dim_counts, missing = _apply_author_template_freqcap(
+            after_freqcap,
+            recent_author_ids=recent_author_ids,
+            recent_template_ids=recent_template_ids,
+        )
+        missing_history_fields = missing
+        freqcap_counts.update(dim_counts)
+    else:
+        # Feed：不强制作者/模板冷却（V1 可选，这里默认跳过）
+        missing_history_fields = []
+
+    candidate_pool_size_after_freqcap = len(after_freqcap)
+
+    ranked: list[ScoredCandidate]
+    if scene == "feed":
+        # MMR 前截断，避免性能问题
+        top_n = int(cfg.top_n_for_mmr) if int(cfg.top_n_for_mmr) > 0 else len(after_freqcap)
+        mmr_pool = after_freqcap[:top_n]
+        ranked = _mmr_rerank(candidates=mmr_pool, k=int(k), lam=cfg.mmr_lambda)
+    else:
+        ranked = after_freqcap[: max(0, int(k))]
+
+    meta = RerankMeta(
+        candidate_pool_size_after_dedup=int(candidate_pool_size_after_dedup),
+        candidate_pool_size_after_freqcap=int(candidate_pool_size_after_freqcap),
+        missing_history_fields=missing_history_fields,
+        freqcap_filtered_counts=freqcap_counts,
+    )
+    return RerankResult(ranked_items=ranked, meta=meta)
+