feat(b0): 注入透明可控版后端 — PUT override(pin/排除/recent_n) + 选择函数加参 + draft 同读

- selection.select_relevant_entities 加 pinned/excluded frozenset 入参；新理由 author_pin（末位）
- assemble 加 override 关键字参（recent_n 覆盖回看章数 + pin/排除）；GET/PUT/draft 同读同一覆盖（不变量 #6 作者兜底）
- 新 domain/injection_repo.py（InjectionOverride/EntityRef/SqlInjectionOverrideRepo，upsert 只 flush）
- 新表 chapter_injection（迁移 ad2c4c663daf，唯一 project_id+chapter_no；复用 outline 行已否决）
- PUT/GET injection 端点 + InjectionOverrideRequest/回显 pinned/excluded；recent_n 1..20 校验 422
- 单测：selection pin/排除/exclude>pin + assemble override + 端点 PUT/404/422；regen TS 客户端
- 门禁绿：ruff/format · mypy 163 · alembic 无漂移 · pytest 476

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

packages/core/tests/test_memory.py

@@ -200,6 +200,99 @@ def test_union_dedups_reasons_sorted() -> None:
     ]
 
 
+# ---- author override: pin / exclude / recent_n (B0 可控版) ----
+
+
+def test_pin_forces_inclusion_with_author_pin_reason() -> None:
+    # 路人甲零自动理由——pin 强制纳入并加 author_pin。
+    outline = OutlineView(volume=1, chapter_no=1, beats={})
+    trace = select_relevant_entities(
+        outline=outline,
+        characters=[char("路人甲", role="配角")],
+        world_entities=[],
+        recent_digests=[],
+        pinned=frozenset({("character", "路人甲")}),
+    )
+    selected = [e for e in trace.selected if e.name == "路人甲"]
+    assert len(selected) == 1
+    assert selected[0].reasons == ["author_pin"]
+
+
+def test_pin_appends_author_pin_to_existing_reasons() -> None:
+    outline = OutlineView(volume=1, chapter_no=1, beats={})
+    trace = select_relevant_entities(
+        outline=outline,
+        characters=[char("林动", role="主角")],
+        world_entities=[],
+        recent_digests=[],
+        pinned=frozenset({("character", "林动")}),
+    )
+    main = next(e for e in trace.selected if e.name == "林动")
+    assert main.reasons == ["main_character", "author_pin"]  # 规范顺序，author_pin 末位
+
+
+def test_exclude_removes_auto_selected_entity() -> None:
+    # 主角林动本会自动入选——excluded 强制剔除。
+    outline = OutlineView(volume=1, chapter_no=1, beats={})
+    trace = select_relevant_entities(
+        outline=outline,
+        characters=[char("林动", role="主角")],
+        world_entities=[],
+        recent_digests=[],
+        excluded=frozenset({("character", "林动")}),
+    )
+    assert all(e.name != "林动" for e in trace.selected)
+
+
+def test_exclude_wins_over_pin() -> None:
+    # 同一实体同时 pin + exclude（前端不会，但防御）：排除优先。
+    outline = OutlineView(volume=1, chapter_no=1, beats={})
+    trace = select_relevant_entities(
+        outline=outline,
+        characters=[char("林动", role="主角")],
+        world_entities=[],
+        recent_digests=[],
+        pinned=frozenset({("character", "林动")}),
+        excluded=frozenset({("character", "林动")}),
+    )
+    assert all(e.name != "林动" for e in trace.selected)
+
+
+async def test_assemble_override_pins_and_excludes() -> None:
+    from ww_core.domain.injection_repo import EntityRef, InjectionOverride
+
+    repos = build_repos(
+        characters=[char("林动", role="主角"), char("路人乙", role="龙套")],
+        spec=ProjectSpecView(title="书"),
+    )
+    override = InjectionOverride(
+        pinned=[EntityRef(kind="character", name="路人乙")],
+        excluded=[EntityRef(kind="character", name="林动")],
+    )
+    ctx = await assemble(repos, PROJECT, 1, override=override)
+    names = {e.name for e in ctx.selection.selected}
+    assert "路人乙" in names  # pin 强制纳入
+    assert "林动" not in names  # exclude 强制剔除
+
+
+async def test_assemble_override_recent_n_limits_digests() -> None:
+    from ww_core.domain.injection_repo import InjectionOverride
+
+    digests = [DigestView(chapter_no=n, facts={"entities": [f"实体{n}"]}) for n in range(1, 6)]
+    world = [WorldEntityView(type="设定", name=f"实体{n}") for n in range(1, 6)]
+    repos = build_repos(
+        outline={10: OutlineView(volume=1, chapter_no=10, beats={})},
+        world=world,
+        digests=digests,
+        spec=ProjectSpecView(title="书"),
+    )
+    # recent_n=1 → 只回看最近一章（第5章）的实体5 命中 recent_digest。
+    ctx = await assemble(repos, PROJECT, 10, override=InjectionOverride(recent_n=1))
+    names = {e.name for e in ctx.selection.selected}
+    assert "实体5" in names
+    assert "实体1" not in names
+
+
 # ---- render_cards ----