fix:

1. 修复安卓部分机型顶部安全区遮挡回忆录标题的问题；
2. 降低封面图生成阈值和展示逻辑，独立封面图未生成时，使用正文图；
3. 去掉“嗯。”生硬回答，去掉不合理段首承接词；
4. 新增章节封面所需最少插图数的配置项

api/tests/test_chapter_cover_fallback_inline.py

@@ -0,0 +1,57 @@
+"""章节封面：无 cover_asset_id 时用正文首张 asset:// 作列表封面。"""
+
+from unittest.mock import MagicMock
+
+from app.features.memoir.helpers import chapter_cover_to_dict
+
+
+def test_cover_falls_back_to_first_inline_asset_url() -> None:
+    ch = MagicMock(spec=[])
+    ch.canonical_markdown = "正文\n\n![场景](asset://img-1)"
+    ch.cover_asset_id = None
+    ch.story_links = []
+    ch.images = []
+    m = chapter_cover_to_dict(
+        ch,
+        asset_url_map={"img-1": "https://cos.example.com/signed-1"},
+        markdown_for_response=None,
+    )
+    assert m is not None
+    assert m["url"] == "https://cos.example.com/signed-1"
+    assert m["status"] == "completed"
+
+
+def test_cover_from_reading_segments_when_canonical_has_no_asset() -> None:
+    """分段快照里有 asset://，章节 canonical 未带图时仍能出封面 URL。"""
+    ch = MagicMock(spec=[])
+    ch.canonical_markdown = "只有文字没有图" * 20
+    ch.cover_asset_id = None
+    ch.story_links = []
+    ch.images = []
+    ch.reading_segments_json = [
+        {"story_id": "s1", "body_markdown": "![景](asset://seg-1)"}
+    ]
+    m = chapter_cover_to_dict(
+        ch,
+        asset_url_map={"seg-1": "https://cos.example.com/seg"},
+        markdown_for_response=None,
+    )
+    assert m is not None
+    assert m["url"] == "https://cos.example.com/seg"
+
+
+def test_cover_prefers_cover_asset_id_over_inline() -> None:
+    ch = MagicMock(spec=[])
+    ch.canonical_markdown = "![a](asset://inline-1)"
+    ch.cover_asset_id = "cover-99"
+    ch.story_links = []
+    ch.images = []
+    m = chapter_cover_to_dict(
+        ch,
+        asset_url_map={
+            "inline-1": "https://cos.example.com/inline",
+            "cover-99": "https://cos.example.com/cover",
+        },
+        markdown_for_response=None,
+    )
+    assert m["url"] == "https://cos.example.com/cover"

api/tests/test_cover_eligibility_effective_markdown.py

@@ -0,0 +1,54 @@
+"""封面闸门：canonical 未落库时须用物化正文计数 asset://。"""
+
+from unittest.mock import MagicMock, patch
+
+from app.features.memoir.cover_eligibility import (
+    chapter_eligible_for_cover_by_inline_body_image_count,
+    chapter_needs_cover_enqueue,
+    count_chapter_inline_body_images,
+    effective_chapter_markdown_for_cover_gates,
+)
+
+
+def test_effective_markdown_falls_back_to_materialize_when_canonical_empty() -> None:
+    ch = MagicMock()
+    ch.canonical_markdown = ""
+    ch.story_links = [MagicMock()]
+    with patch(
+        "app.features.memoir.chapter_markdown_compose.materialize_chapter_markdown_from_loaded_chapter",
+        return_value="正文\n\n![x](asset://a1)",
+    ):
+        assert "asset://" in effective_chapter_markdown_for_cover_gates(ch)
+
+
+def test_count_uses_effective_when_canonical_empty() -> None:
+    ch = MagicMock()
+    ch.canonical_markdown = ""
+    ch.story_links = [MagicMock()]
+    with patch(
+        "app.features.memoir.chapter_markdown_compose.materialize_chapter_markdown_from_loaded_chapter",
+        return_value="![alt](asset://id1)",
+    ):
+        assert count_chapter_inline_body_images(ch) == 1
+
+
+def test_eligible_with_explicit_markdown_override() -> None:
+    ch = MagicMock()
+    ch.canonical_markdown = ""
+    assert chapter_eligible_for_cover_by_inline_body_image_count(
+        ch, markdown="![a](asset://x)"
+    )
+
+
+def test_needs_cover_enqueue_uses_materialized_body() -> None:
+    ch = MagicMock()
+    ch.canonical_markdown = ""
+    ch.cover_asset_id = None
+    ch.story_links = [MagicMock(story=MagicMock())]
+    link = ch.story_links[0]
+    link.story = MagicMock()
+    with patch(
+        "app.features.memoir.chapter_markdown_compose.materialize_chapter_markdown_from_loaded_chapter",
+        return_value="故事\n\n![a](asset://z)",
+    ):
+        assert chapter_needs_cover_enqueue(ch) is True

api/tests/test_reply_segments.py

@@ -3,6 +3,7 @@
 from app.agents.chat.reply_limits import (
     nonempty_segments_or_fallback,
     segments_from_llm_response,
+    strip_leading_en_period_ack_for_chat,
     strip_markdown_for_chat,
     strip_parenthetical_asides_for_chat,
 )
@@ -58,3 +59,15 @@ def test_segments_strip_parentheticals_before_split():
 
 def test_strip_parenthetical_multiple_passes():
     assert strip_parenthetical_asides_for_chat("a（一）b（二）c") == "abc"
+
+
+def test_strip_leading_en_period_ack():
+    assert strip_leading_en_period_ack_for_chat("嗯。后面正文") == "后面正文"
+    assert strip_leading_en_period_ack_for_chat("嗯嗯。后面") == "后面"
+    assert strip_leading_en_period_ack_for_chat("  嗯。  第二句") == "第二句"
+    assert strip_leading_en_period_ack_for_chat("句中嗯。不打头") == "句中嗯。不打头"
+
+
+def test_segments_strip_leading_en_ack():
+    assert segments_from_llm_response("嗯。只有一句", max_segments=3) == ["只有一句"]
+    assert segments_from_llm_response("嗯。A[SPLIT]嗯。B", max_segments=3) == ["A", "B"]