feat(writer): add build_contexts (template+rules -> GenerationContext list)

src/genesis/writer/context_builder.py

@@ -0,0 +1,31 @@
+"""上下文装配：StructuredSource + 模板 + 规则 → 有序 GenerationContext 列表（Phase 5）。"""
+from __future__ import annotations
+
+from genesis.data_models import StructuredSource
+from genesis.services.rag_service import CannedRagService
+from genesis.writer.models import ChapterSpec, GenerationContext
+from genesis.writer.template_mapper import map_template
+
+
+def build_contexts(structured_source: StructuredSource, samples_dir: str = "samples") -> list[GenerationContext]:
+    specs: list[ChapterSpec] = map_template(structured_source.template)
+    rag = CannedRagService(samples_dir=samples_dir)
+    out: list[GenerationContext] = []
+    for spec in specs:
+        # RagService 方法为同步（P5-T3 裁定）
+        write_rules = rag.retrieve_write_rules(spec.chapter_id)
+        design_rules = rag.retrieve_design_rules(spec.chapter_id)
+        used = (structured_source.template.styles or {}).get("used", [])
+        out.append(
+            GenerationContext(
+                chapter_id=spec.chapter_id,
+                title=spec.title,
+                template_marker=spec,
+                structured_source=structured_source,
+                write_rules=write_rules,
+                design_rules=design_rules,
+                template_styles=set(used),
+                prior_state=None,
+            )
+        )
+    return out

tests/test_phase5_context_builder.py

@@ -0,0 +1,30 @@
+from types import SimpleNamespace
+
+from genesis.data_models import ParsedTemplate, ChapterMarker
+from genesis.writer.context_builder import build_contexts
+from genesis.writer.models import GenerationContext
+
+
+def _ss():
+    template = ParsedTemplate(
+        file_name="t.docx",
+        sections=[
+            ChapterMarker(type="heading", name="はじめに", level=1),
+            ChapterMarker(type="placeholder", name="section:introduction", level=0),
+        ],
+        placeholders={},
+        styles={"defined": ["Heading1"], "used": ["Heading1", "Normal"]},
+    )
+    return SimpleNamespace(template=template)
+
+
+def test_build_contexts_maps_chapters():
+    ctxs = build_contexts(_ss(), samples_dir="nonexistent_dir_xyz")
+    assert len(ctxs) == 1
+    c = ctxs[0]
+    assert isinstance(c, GenerationContext)
+    assert c.chapter_id == "introduction"
+    assert c.write_rules == []          # 样本缺失 -> 空
+    assert c.design_rules == []
+    assert c.template_styles == {"Heading1", "Normal"}
+    assert c.template_marker.section_placeholder == "section:introduction"