Fix SSE route dependency and align architecture docs

backend/app/infrastructure/parser/local_chunk_builder.py

@@ -0,0 +1,66 @@
+"""Local chunk builder adapter for the migrated backend architecture."""
+
+from __future__ import annotations
+
+from app.domain.documents import Chunk, ChunkBuilder, ParsedDocument
+from app.services.embedding.text_chunker import RegulationChunker
+
+
+class LocalRegulationChunkBuilder(ChunkBuilder):
+    """Adapt the existing markdown chunker to the new chunk builder port."""
+
+    def __init__(self, *, chunk_size: int = 512, chunk_overlap: int = 50) -> None:
+        self.chunker = RegulationChunker(
+            chunk_size=chunk_size,
+            chunk_overlap=chunk_overlap,
+        )
+
+    def build(
+        self,
+        *,
+        parsed_document: ParsedDocument,
+        regulation_type: str,
+        version: str,
+    ) -> list[Chunk]:
+        markdown_text = parsed_document.raw_text.strip()
+        if not markdown_text:
+            return []
+
+        legacy_chunks = self.chunker.chunk_document(
+            markdown_text,
+            doc_id=parsed_document.doc_id,
+            doc_name=parsed_document.doc_name,
+            regulation_type=regulation_type,
+            version=version,
+        )
+
+        chunks: list[Chunk] = []
+        for item in legacy_chunks:
+            metadata = {
+                "section_number": item.metadata.section_number,
+                "section_title": item.metadata.section_title,
+                "clause_number": item.metadata.clause_number,
+                "start_position": item.metadata.start_position,
+                "end_position": item.metadata.end_position,
+                "token_count": item.token_count,
+                "source": "local_chunker",
+            }
+            section_path = [value for value in [item.metadata.section_number, item.metadata.section_title] if value]
+            chunks.append(
+                Chunk(
+                    chunk_id=item.metadata.chunk_id,
+                    doc_id=parsed_document.doc_id,
+                    doc_name=parsed_document.doc_name,
+                    content=item.content,
+                    embedding_text=item.content,
+                    section_title=item.metadata.section_title or item.metadata.section_number,
+                    section_path=section_path,
+                    page_number=item.metadata.page_number,
+                    regulation_type=regulation_type,
+                    version=version,
+                    semantic_id=item.metadata.clause_number,
+                    block_type="local_markdown_chunk",
+                    metadata=metadata,
+                )
+            )
+        return chunks