refactor: pipeline._convert in Teilschritte zerlegt (QA R5)

_convert (zuletzt 153 Zeilen) orchestriert jetzt nur noch die Teilschritte
_prepare_docs, _build_structure, _render (mit _report_wrap_markers und
_collect_remaining_media) und _assemble. Längste Funktion im Modul: 48 Zeilen.
Keine Verhaltensänderung: Die Ausgabe aller vier Beispielbücher (Standard
und end-of-book) ist bis auf Zeitstempel und Pfade byteidentisch.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

epub2md/pipeline.py

@@ -131,11 +131,36 @@ def _load_docs(reader: EpubReader, package: Any, diag: Diagnostics) -> list[Doc]
 def _convert(reader: EpubReader, input_path: Path, output_dir: Path, opts: Options, diag: Diagnostics,
              generated_at: str, sha: str) -> Result:
     package = reader.load_package()
-    md = package.metadata
+    diag.step(f"EPUB {package.version}: {package.metadata.title!r}, {len(package.spine)} Spine-Dokumente")
-    diag.step(f"EPUB {package.version}: {md.title!r}, {len(package.spine)} Spine-Dokumente")
     docs = _load_docs(reader, package, diag)
+    _prepare_docs(docs, package, diag)
+    notes, chapters, resolver = _build_structure(docs, package, opts, diag)
+    rendered = _render(reader, package, chapters, resolver, notes, opts, diag)
+    files, all_chapters, report = _assemble(input_path, output_dir, opts, diag, generated_at, sha, package, docs,
+                                            notes, chapters, resolver, rendered)
+    if opts.dry_run:
+        return Result(report=report, chapters=all_chapters, files=files, output_dir=output_dir)
 
-    # --- normalization and HTML-TOC handling
+    _write_output(reader, input_path, output_dir, opts, files, rendered.media)
+    if opts.report:
+        report_path = Path(opts.report)
+        report_path.parent.mkdir(parents=True, exist_ok=True)
+        report_path.write_text(writer.to_json(report), encoding="utf-8")
+    return Result(report=report, chapters=all_chapters, files=files, output_dir=output_dir)
+
+
+@dataclass
+class _Rendered:
+    renderer: Renderer
+    media: MediaRegistry
+    cover_out: str
+    endnotes: Chapter | None
+    endnotes_md: str
+    skipped_formula_images: int
+
+
+def _prepare_docs(docs: list[Doc], package: Any, diag: Diagnostics) -> None:
+    """Normalize publisher markup and drop HTML tables of contents that NAV/NCX already cover."""
     title_tables = book_uses_title_tables(docs)
     for doc in docs:
         normalize_doc(doc, diag, title_tables)
@@ -156,13 +181,16 @@ def _convert(reader: EpubReader, input_path: Path, output_dir: Path, opts: Optio
         for d in docs:
             d.skipped = ""
 
-    # --- notes, chapters, links
+
+def _build_structure(docs: list[Doc], package: Any, opts: Options,
+                     diag: Diagnostics) -> tuple[Any, list[Chapter], LinkResolver]:
+    """Notes, chapter units with file names, and the link resolver (incl. NAV/NCX targets)."""
+    md = package.metadata
     notes = collect_notes(docs, opts.footnotes, diag)
     diag.step(f"{len(notes.notes)} Anmerkungen erkannt")
     chapters = ChapterBuilder(opts.chapter_level, package.toc, diag, md.title, md.authors).build(docs)
     _assign_filenames(chapters, opts.slug_language)
-    readme_path = "README.md" if opts.toc else None
+    resolver = LinkResolver(docs, chapters, notes, "README.md" if opts.toc else None)
-    resolver = LinkResolver(docs, chapters, notes, readme_path)
     nav_targets: list[tuple[str, str]] = []
 
     def walk(entries: list[Any]) -> None:
@@ -174,8 +202,13 @@ def _convert(reader: EpubReader, input_path: Path, output_dir: Path, opts: Optio
     walk(package.toc)
     resolver.add_targets(nav_targets)
     diag.step(f"{len(chapters)} Kapitel gebildet")
+    return notes, chapters, resolver
 
-    # --- rendering
+
+def _render(reader: EpubReader, package: Any, chapters: list[Chapter], resolver: LinkResolver, notes: Any,
+            opts: Options, diag: Diagnostics) -> _Rendered:
+    """Render all chapters (and the end-of-book notes file) to Markdown and register media."""
+    md = package.metadata
     media = MediaRegistry(package, opts.images, opts.slug_language)
     cover_out = ""
     if md.cover_path and opts.extract_media and reader.exists(md.cover_path):
@@ -196,13 +229,7 @@ def _convert(reader: EpubReader, input_path: Path, output_dir: Path, opts: Optio
         ch.markdown = renderer.render_chapter(ch)
         ch.stats.word_count = _word_count(ch.markdown)
         _check_chapter_size(ch, opts.chapter_level, diag)
-    wraps: dict[str, int] = {}
+    _report_wrap_markers(renderer, diag)
-    for block in renderer.code_blocks:
-        if block["wrap_lines_joined"]:
-            wraps[block["chapter"]] = wraps.get(block["chapter"], 0) + block["wrap_lines_joined"]
-    for chapter_file, joined in wraps.items():
-        diag.info("wrap-markers-joined", f"{joined} Druck-Zeilenumbrüche (↪) in Codeblöcken zusammengeführt.",
-                  chapter_file, chapter_file)
     endnotes: Chapter | None = None
     endnotes_md = ""
     if opts.footnotes == "end-of-book" and renderer.book_notes:
@@ -211,8 +238,23 @@ def _convert(reader: EpubReader, input_path: Path, output_dir: Path, opts: Optio
         endnotes.filename = renderer.endnotes_file
         endnotes.stats.footnotes = len(renderer.book_notes)
         endnotes.stats.word_count = _word_count(endnotes_md)
+    skipped = _collect_remaining_media(reader, package, media, renderer, opts)
+    return _Rendered(renderer, media, cover_out, endnotes, endnotes_md, skipped)
 
-    # --- remaining media (fonts, css, audio, unreferenced images)
+
+def _report_wrap_markers(renderer: Renderer, diag: Diagnostics) -> None:
+    wraps: dict[str, int] = {}
+    for block in renderer.code_blocks:
+        if block["wrap_lines_joined"]:
+            wraps[block["chapter"]] = wraps.get(block["chapter"], 0) + block["wrap_lines_joined"]
+    for chapter_file, joined in wraps.items():
+        diag.info("wrap-markers-joined", f"{joined} Druck-Zeilenumbrüche (↪) in Codeblöcken zusammengeführt.",
+                  chapter_file, chapter_file)
+
+
+def _collect_remaining_media(reader: EpubReader, package: Any, media: MediaRegistry, renderer: Renderer,
+                             opts: Options) -> int:
+    """Register fonts, CSS, audio and unreferenced images; returns the number of formula images replaced by TeX."""
     skipped_formula_images = 0
     if opts.extract_media:
         for item in package.manifest.values():
@@ -229,11 +271,18 @@ def _convert(reader: EpubReader, input_path: Path, output_dir: Path, opts: Optio
     for mf in media.files.values():
         if mf.data is None and reader.exists(mf.source):
             mf.size = reader.names[mf.source].file_size
+    return skipped_formula_images
 
-    # --- assemble output files in memory
+
-    unresolved_notes = [n for n in notes.notes.values() if n.ref_count and not n.label and notes.extracted]
+def _assemble(input_path: Path, output_dir: Path, opts: Options, diag: Diagnostics, generated_at: str, sha: str,
-    for n in unresolved_notes:
+              package: Any, docs: list[Doc], notes: Any, chapters: list[Chapter], resolver: LinkResolver,
-        diag.warn("note-not-rendered", "Anmerkung wurde referenziert, aber nicht ausgegeben.", n.key)
+              rendered: _Rendered) -> tuple[dict[str, str], list[Chapter], dict[str, Any]]:
+    """Build all output files in memory (chapters, README, metadata, manifest, report, diagnostics)."""
+    md = package.metadata
+    renderer, media, endnotes = rendered.renderer, rendered.media, rendered.endnotes
+    for n in notes.notes.values():
+        if n.ref_count and not n.label and notes.extracted:
+            diag.warn("note-not-rendered", "Anmerkung wurde referenziert, aber nicht ausgegeben.", n.key)
     opf_dir = posixpath.dirname(package.opf_path)
     files: dict[str, str] = {}
     for ch in chapters:
@@ -243,12 +292,12 @@ def _convert(reader: EpubReader, input_path: Path, output_dir: Path, opts: Optio
         files[ch.filename] = front + ch.markdown
     if endnotes is not None:
         front = writer.chapter_frontmatter(endnotes, md, input_path.name, opf_dir, 0) if opts.frontmatter else ""
-        files[endnotes.filename] = front + endnotes_md
+        files[endnotes.filename] = front + rendered.endnotes_md
     all_chapters = chapters + ([endnotes] if endnotes else [])
 
     stats = _book_stats(all_chapters, media, renderer, diag)
     if opts.toc:
-        files["README.md"] = writer.readme(md, chapters, endnotes, package.toc, resolver, stats, cover_out,
+        files["README.md"] = writer.readme(md, chapters, endnotes, package.toc, resolver, stats, rendered.cover_out,
                                            package.version, input_path.name, opts.command, str(output_dir))
     existing = {mf.output for mf in media.files.values()} if opts.extract_media else set()
     if opts.copy_original:
@@ -261,23 +310,14 @@ def _convert(reader: EpubReader, input_path: Path, output_dir: Path, opts: Optio
     stats["warnings"] = diag.count("warning")
 
     report = _report(input_path, sha, generated_at, package, opts, all_chapters, media, renderer, notes, diag,
-                     docs, broken, skipped_formula_images)
+                     docs, broken, rendered.skipped_formula_images)
-    files["metadata.yaml"] = writer.metadata_yaml(md, input_path.name, sha, package.version, cover_out,
+    files["metadata.yaml"] = writer.metadata_yaml(md, input_path.name, sha, package.version, rendered.cover_out,
                                                   opts.public(), generated_at)
     files["manifest.json"] = writer.to_json(_manifest(md, all_chapters, media, diag))
     files["conversion-report.json"] = writer.to_json(report)
     files["diagnostics/warnings.md"] = writer.warnings_md(diag)
     files["diagnostics/unsupported-elements.md"] = writer.unsupported_md(diag)
-
+    return files, all_chapters, report
-    if opts.dry_run:
-        return Result(report=report, chapters=all_chapters, files=files, output_dir=output_dir)
-
-    _write_output(reader, input_path, output_dir, opts, files, media)
-    if opts.report:
-        report_path = Path(opts.report)
-        report_path.parent.mkdir(parents=True, exist_ok=True)
-        report_path.write_text(writer.to_json(report), encoding="utf-8")
-    return Result(report=report, chapters=all_chapters, files=files, output_dir=output_dir)
 
 
 def _mostly_links(el: Any) -> bool: