feat(eda): render quality global — DPI 220, tablas anchas como imagen, layout side_by_side, índice clicable

Mejoras transversales del motor AutomaticEDA (PDF + PPTX) sobre el modelo de bloques:

1. DPI alto global: toda figura/imagen embebida se rasteriza a 220 dpi (antes 150,
   y en PDF la página se guardaba a ~100 dpi re-rasterizando los imshow). En PDF se
   aplica savefig.dpi=220 a la página; el texto sigue vectorial y seleccionable.
   Permite ampliar en el móvil sin pixelar. Imagen embebida medida: ~1081px (antes ~492px).

2. Tabla ancha → imagen de alta resolución: cuando un DataTable tiene demasiadas
   columnas para ser legible como texto (criterio _table_fits_as_text), se dibuja entera
   como una imagen nítida (nueva función render_table_as_figure_py_datascience: cabecera
   sombreada + zebra) escalada para caber completa, de modo que el lector hace zoom y la
   lee sin perder datos. Las tablas que sí caben siguen como texto seleccionable / tabla
   nativa. Aplica en PDF y PPTX. El df.head de 19 columnas del dataset sintético ya no se
   corta: sale como imagen.

3. Group.layout: nuevo hint retrocompatible (default "stack"). "side_by_side" coloca la
   tabla a la izquierda (~55%) y la figura a la derecha (~45%) en la misma slide PPTX
   (cae a apilado si no hay par tabla+figura o no caben); en PDF se trata como "stack"
   (el ancho A5 móvil no admite dos columnas). Pensado para que el capítulo cat_distr
   ponga el gráfico al lado de la tabla en PPT.

4. Portada con índice clicable: la lista de capítulos pasa de "Este informe incluye..."
   (markdown) a un Heading "Índice" + un TocEntry por capítulo. El renderer registra el
   inicio de cada capítulo y cablea cada entrada como salto real (PDF: link GOTO PyMuPDF;
   PPTX: salto a slide nativo), reutilizando el mecanismo del glosario clicable.

Modelo: Group gana `layout`; nuevo bloque TocEntry; normalizers y __init__ actualizados.
Contrato: documentado en docs/automatic_eda_contract.md §11.4 (incluye el contrato exacto
del campo layout para el agente de cat_distr).

Tests: nuevo render_quality_test.py (13 golden: DPI alto real, tabla ancha→imagen PDF/PPTX,
narrow→texto, side_by_side PPTX dos columnas / PDF apilado, índice clicable PDF+PPTX,
retrocompatibilidad layout por defecto). render_features_test actualizado al índice nuevo.
Suite: 188 passed (módulo) + 38 passed/1 skipped (acceptance + pipeline).

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

python/functions/datascience/automatic_eda/__init__.py

@@ -29,6 +29,7 @@ from .model import (  # noqa: F401
     KVTable,
     Markdown,
     Note,
+    TocEntry,
     as_blocks,
     as_chapters,
     merge_manifest,
@@ -52,6 +53,7 @@ __all__ = [
     "Group",
     "GlossaryEntry",
     "GlossaryCollector",
+    "TocEntry",
     "Chapter",
     "as_blocks",
     "as_chapters",

python/functions/datascience/automatic_eda/chapters/portada.py

@@ -26,7 +26,7 @@ from datetime import datetime, timezone
 
 from .. import model
 
-CHAPTER_VERSION = "1.3.0"
+CHAPTER_VERSION = "1.4.0"
 CHAPTER_ID = "portada"
 CHAPTER_TITLE = "Portada"
 
@@ -120,9 +120,17 @@ def _summary_blocks(summary) -> list:
         # Values pinned to the right margin (numbers flush right, label left).
         blocks.append(model.KVTable(rows=rows, value_align="right"))
     if titles:
-        bullets = "\n".join(f"- {model._safe_str(t)}" for t in titles)
-        blocks.append(model.Markdown(
-            text="Este informe incluye los siguientes capítulos:\n" + bullets))
+        # Clickable index ("Índice"): one TocEntry per chapter title. Each entry
+        # becomes a real jump to that chapter's first page/slide once the document
+        # is laid out (the renderers register every chapter start and wire the
+        # links; ``target_id`` is matched against the chapter title). The cover only
+        # knows chapter titles, so the title doubles as the link target.
+        blocks.append(model.Heading(text="Índice", level=2))
+        for t in titles:
+            label = model._safe_str(t)
+            if not label:
+                continue
+            blocks.append(model.TocEntry(label=label, target_id=label))
     return blocks
 
 

python/functions/datascience/automatic_eda/model.py

@@ -160,11 +160,21 @@ class Group:
     a chapter can give each unit its own page — e.g. one categorical column per
     page (see CAT DISTR). It is purely additive: the default False keeps the plain
     keep-together behaviour for every existing chapter.
+
+    ``layout`` is a hint for how the group's children are arranged:
+    ``"stack"`` (default) keeps the historical top-to-bottom flow; ``"side_by_side"``
+    asks the PPTX renderer to place the group's table to the LEFT and its figure to
+    the RIGHT of the same slide (table ~55% width, figure ~45%), measuring so both
+    fit and falling back to stacking when they do not. The PDF renderer treats
+    ``"side_by_side"`` exactly like ``"stack"`` (the A5 mobile page is too narrow for
+    two readable columns). Unknown values degrade to ``"stack"``. Purely additive:
+    the default keeps every existing chapter unchanged.
     """
 
     blocks: list = field(default_factory=list)
     title: Optional[str] = None
     page_break_before: bool = False
+    layout: str = "stack"
     kind: str = field(default="group", init=False)
 
 
@@ -183,6 +193,22 @@ class GlossaryEntry:
     kind: str = field(default="glossary_entry", init=False)
 
 
+@dataclass
+class TocEntry:
+    """One clickable index (table-of-contents) entry shown on the cover.
+
+    Rendered as a single line — the chapter ``label`` in the accent link colour —
+    that, once the document is laid out, becomes a real click jumping to the first
+    page/slide of the target chapter (PDF link annotation via PyMuPDF; PPTX native
+    slide jump). ``target_id`` is matched against each chapter's ``id`` *and* its
+    ``title`` (the cover only knows chapter titles), so either resolves. If the
+    target cannot be resolved the entry still renders as plain text (never cut)."""
+
+    label: str = ""
+    target_id: str = ""
+    kind: str = field(default="toc_entry", init=False)
+
+
 @dataclass
 class Chapter:
     """An ordered set of blocks with an id, a title and a generation version."""
@@ -207,13 +233,14 @@ _BLOCK_BY_KIND = {
     "note": Note,
     "group": Group,
     "glossary_entry": GlossaryEntry,
+    "toc_entry": TocEntry,
 }
 
 
 def as_block(obj: Any):
     """Coerce a value into a block dataclass. Unknown values become a Note."""
     if isinstance(obj, (Heading, Markdown, KVTable, DataTable, Figure, Image,
-                        Caption, Note, Group, GlossaryEntry)):
+                        Caption, Note, Group, GlossaryEntry, TocEntry)):
         if isinstance(obj, Group):
             obj.blocks = as_blocks(obj.blocks)
         return obj
@@ -259,11 +286,15 @@ def as_block(obj: Any):
                 return Group(blocks=as_blocks(obj.get("blocks")),
                              title=obj.get("title"),
                              page_break_before=bool(
-                                 obj.get("page_break_before", False)))
+                                 obj.get("page_break_before", False)),
+                             layout=_safe_str(obj.get("layout")) or "stack")
             if cls is GlossaryEntry:
                 return GlossaryEntry(key=_safe_str(obj.get("key")),
                                      label=_safe_str(obj.get("label")),
                                      definition=_safe_str(obj.get("definition")))
+            if cls is TocEntry:
+                return TocEntry(label=_safe_str(obj.get("label")),
+                                target_id=_safe_str(obj.get("target_id")))
         except Exception:  # noqa: BLE001 — never raise on a malformed block.
             return Note(text=_safe_str(obj))
     return Note(text=_safe_str(obj))

python/functions/datascience/automatic_eda/render_features_test.py

@@ -298,11 +298,16 @@ def test_cover_first_glossary_last_with_summary():
     headings = [b.text for b in cover.blocks if b.kind == "heading"]
     assert any("Resumen" in h for h in headings), \
         "la portada no incluye el resumen agregado"
-    # The summary reflects the body chapters (e.g. the numeric/categorical ones).
-    cover_text = " ".join(
-        b.text for b in cover.blocks if getattr(b, "kind", "") == "markdown")
-    assert "Distribuciones" in cover_text, \
-        "el resumen de portada no menciona los capítulos del cuerpo"
+    # The index ("Índice") is now a clickable list of TocEntry blocks (one per
+    # body chapter), not a markdown bullet list. Verify both the heading and that
+    # the entries name the body chapters.
+    assert any("Índice" in h for h in headings), \
+        "la portada no incluye la sección Índice"
+    toc_labels = " ".join(
+        getattr(b, "label", "") for b in cover.blocks
+        if getattr(b, "kind", "") == "toc_entry")
+    assert "Distribuciones" in toc_labels, \
+        "el índice de portada no menciona los capítulos del cuerpo"
 
 
 # --------------------------------------------------------------------------- #

python/functions/datascience/automatic_eda/render_pdf_impl.py

@@ -46,11 +46,23 @@ _MUTED = "#8a8a8a"
 _RULE = "#cccccc"
 _HEAD_BG = "#eef3f6"
 
+# Rasterization DPI for every embedded raster (figure/table image) AND for the
+# page save itself. Raised from the old 150/default-100 to 220 so a reader can
+# pinch-zoom on a phone and still see crisp detail (axis labels, table cells)
+# without pixelation. Text stays vectorial (pdf.fonttype=42) so it remains
+# selectable regardless of DPI — only the embedded images gain resolution. 220 is
+# a deliberate balance: noticeably sharper than 150 while keeping the file size
+# reasonable. ``savefig.dpi`` matters because matplotlib re-rasterizes each
+# ``imshow`` when PdfPages writes the page; without it the final image would land
+# at ~100 dpi no matter how sharp the intermediate PNG was.
+_RASTER_DPI = 220
+
 _RC = {
     "font.size": 10,
     "font.family": "sans-serif",
     "figure.facecolor": "white",
     "savefig.facecolor": "white",
+    "savefig.dpi": _RASTER_DPI,
     "pdf.fonttype": 42,  # embed TrueType — text stays selectable on mobile.
 }
 
@@ -80,6 +92,10 @@ class _PdfState:
         # points (1/72") with a top-left origin — same convention as PyMuPDF.
         self.term_sources = []       # [{key, page, rect:[x0,y0,x1,y1]}]
         self.term_dests = {}         # key -> {page, point:[x,y]}
+        # Clickable index (cover → chapter). Sources are the cover's TocEntry
+        # rects; chapter_starts maps a chapter id AND its title to its first page.
+        self.toc_sources = []        # [{target_id, page, rect:[x0,y0,x1,y1]}]
+        self.chapter_starts = {}     # id|title -> {page, point:[x,y]}
 
 
 # --------------------------------------------------------------------------- #
@@ -385,6 +401,57 @@ def _col_widths(header: list, rows: list, fs: float) -> list:
     return widths
 
 
+# Minimal legible characters reserved per column when deciding whether a table
+# can be shown as selectable text. Below this width per column the cells become
+# unreadable, so the table is rasterized to a zoomable high-res image instead.
+_MIN_LEGIBLE_CHARS = 8
+
+
+def _table_fits_as_text(header: list, rows: list) -> bool:
+    """True when the table fits the usable width as readable text.
+
+    A table whose columns cannot each get a minimal legible width within the A5
+    usable width (typically many columns, e.g. a 19-column ``df.head``) is flagged
+    so it is rendered as a single high-resolution image — the reader zooms in on
+    the phone and reads every cell, nothing cut — instead of being squeezed until
+    unreadable. Narrow tables (few columns) keep the selectable-text rendering."""
+    header = header or []
+    rows = rows or []
+    ncol = len(header) if header else (len(rows[0]) if rows else 1)
+    ncol = max(1, ncol)
+    cw = tl.avg_char_width_in(_FS_CELL)
+    min_needed = ncol * (_MIN_LEGIBLE_CHARS * cw + _CELL_PAD * 2)
+    return min_needed <= _USABLE_W
+
+
+def _table_figure_block(block):
+    """Wrap a too-wide table as a lazily-rasterized Figure (cached on the block).
+
+    The table is drawn once via ``render_table_as_figure`` (header shading + zebra)
+    and embedded as one high-res image scaled to fit entirely. The same Figure is
+    reused for measuring and placing so keep-together stays consistent. The table
+    title/note are drawn inside the image (self-describing when zoomed/shared), so
+    the block-level caption is left empty to avoid a duplicate title."""
+    cached = getattr(block, "_aeda_tablefig", None)
+    if cached is not None:
+        return cached
+    header = list(getattr(block, "header", []) or [])
+    rows = list(getattr(block, "rows", []) or [])
+    title = getattr(block, "title", None)
+    note = getattr(block, "note", None)
+
+    def _make():
+        from datascience.render_table_as_figure import render_table_as_figure
+        return render_table_as_figure(header, rows, title=title, note=note)
+
+    fig = model.Figure(make=_make, caption=None)
+    try:
+        block._aeda_tablefig = fig
+    except Exception:  # noqa: BLE001 — block may reject attributes; degrade.
+        pass
+    return fig
+
+
 def _wrap_row(cells: list, widths: list, fs: float) -> list:
     """Wrap each cell to its column width → list of line-lists per cell."""
     out = []
@@ -424,11 +491,16 @@ def _draw_table_row(st: _PdfState, cells_lines: list, widths: list, fs: float,
 
 
 def _place_data_table(st: _PdfState, block) -> None:
+    header = list(getattr(block, "header", []) or [])
+    rows = list(getattr(block, "rows", []) or [])
+    # Too many columns to be legible as text → render the whole table as one
+    # high-res image, scaled to fit entirely (the reader zooms to read it).
+    if not _table_fits_as_text(header, rows):
+        _place_figure(st, _table_figure_block(block))
+        return
     title = getattr(block, "title", None)
     if title:
         _place_heading(st, model.Heading(title, level=2))
-    header = list(getattr(block, "header", []) or [])
-    rows = list(getattr(block, "rows", []) or [])
     fs = _FS_CELL
     widths = _col_widths(header, rows, fs)
     header_lines = _wrap_row(header, widths, fs) if header else None
@@ -486,8 +558,11 @@ def _resolve_figure(block):
 
 
 def _png_from_figure(fig) -> bytes:
+    # ``bbox_inches='tight'`` is kept so the real aspect ratio is what we measure
+    # and place. The page save (savefig.dpi in _RC) re-rasterizes this at the same
+    # high DPI, so the embedded image stays crisp for phone zoom.
     buf = io.BytesIO()
-    fig.savefig(buf, format="png", dpi=150, bbox_inches="tight")
+    fig.savefig(buf, format="png", dpi=_RASTER_DPI, bbox_inches="tight")
     buf.seek(0)
     return buf.read()
 
@@ -729,12 +804,16 @@ def _measure_data_table(block) -> float:
     Counts the optional title heading, the wrapped header row, every wrapped data
     row (per-column wrap via the same ``_col_widths``/``_wrap_row`` the placer
     uses) and the optional note. Keep this in sync with ``_place_data_table``."""
+    header = list(getattr(block, "header", []) or [])
+    rows = list(getattr(block, "rows", []) or [])
+    # Mirror the placer: a too-wide table is drawn as a single image, so its
+    # keep-together height is the image's, not the (squeezed) text layout's.
+    if not _table_fits_as_text(header, rows):
+        return _measure_figure_like(_table_figure_block(block))
     h = 0.0
     title = getattr(block, "title", None)
     if title:
         h += _measure_heading_text(title, 2)
-    header = list(getattr(block, "header", []) or [])
-    rows = list(getattr(block, "rows", []) or [])
     fs = _FS_CELL
     widths = _col_widths(header, rows, fs)
     lh = tl.line_height_in(fs)
@@ -766,6 +845,10 @@ def _measure_block(st: _PdfState, block) -> float:
             lines = tl.wrap(getattr(block, "text", ""),
                             tl.chars_per_line(_USABLE_W, _FS_NOTE))
             return tl.line_height_in(_FS_NOTE) * len(lines) + _GAP
+        if kind == "toc_entry":
+            lines = tl.wrap(tl.strip_inline_md(getattr(block, "label", "")),
+                            tl.chars_per_line(_USABLE_W - 0.22, _FS_BODY)) or [""]
+            return tl.line_height_in(_FS_BODY) * len(lines) + _GAP * 0.4
         if kind == "kv_table":
             return _measure_kv_table(block)
         if kind == "data_table":
@@ -850,6 +933,38 @@ def _place_glossary_entry(st: _PdfState, block) -> None:
     st.y += _GAP * 0.5
 
 
+def _place_toc_entry(st: _PdfState, block) -> None:
+    """Render one clickable index line and record it as a link source.
+
+    Drawn as a bulleted line in the accent link colour; its rectangle is recorded
+    in ``st.toc_sources`` so the post-processor turns it into a real jump to the
+    target chapter's first page. If the target is never resolved the line still
+    shows as plain (accent) text — never cut, never broken."""
+    label = tl.strip_inline_md(getattr(block, "label", "")) or ""
+    target_id = getattr(block, "target_id", "") or ""
+    fs = _FS_BODY
+    lh = tl.line_height_in(fs)
+    bullet = "•  "
+    indent = 0.22
+    max_chars = tl.chars_per_line(_USABLE_W - indent, fs)
+    lines = tl.wrap(label, max_chars) or [""]
+    for idx, ln in enumerate(lines):
+        _ensure_space(st, lh)
+        x = _ML
+        st.fig.text(_xf(x), _yf(st.y), bullet if idx == 0 else "   ",
+                    fontsize=fs, color=_LINK, ha="left", va="top")
+        x += indent
+        w = _text_width_in(st, ln, fs, False)
+        st.fig.text(_xf(x), _yf(st.y), ln, fontsize=fs, color=_LINK,
+                    ha="left", va="top")
+        if target_id and idx == 0:
+            st.toc_sources.append({
+                "target_id": target_id, "page": st.page - 1,
+                "rect": _pt_rect(_ML, st.y, x + w, st.y + lh)})
+        st.y += lh
+    st.y += _GAP * 0.4
+
+
 _PLACERS = {
     "heading": _place_heading,
     "markdown": _place_markdown,
@@ -861,6 +976,7 @@ _PLACERS = {
     "note": _place_note,
     "group": _place_group,
     "glossary_entry": _place_glossary_entry,
+    "toc_entry": _place_toc_entry,
 }
 
 
@@ -892,6 +1008,15 @@ def render_pdf(chapters: list, out_path: str, meta: dict = None) -> dict:
                     st.chapter = ch
                     st.chapter_pages = 0
                     _new_page(st)  # each chapter starts on a fresh page.
+                    # Record this chapter's first page as a link target for the
+                    # cover index (keyed by id AND title, since the cover only
+                    # knows titles). Point is the top of the content area.
+                    _start = {"page": st.page - 1,
+                              "point": [_ML * 72.0, _CONTENT_TOP * 72.0]}
+                    if ch.id:
+                        st.chapter_starts[ch.id] = _start
+                    if getattr(ch, "title", ""):
+                        st.chapter_starts.setdefault(ch.title, _start)
                     for block in ch.blocks:
                         placer = _PLACERS.get(getattr(block, "kind", ""),
                                               _place_note)
@@ -924,7 +1049,7 @@ def render_pdf(chapters: list, out_path: str, meta: dict = None) -> dict:
 
     note = f"{n_pages} páginas"
     if n_links:
-        note += f" · {n_links} enlaces de glosario"
+        note += f" · {n_links} enlaces internos"
     if notes:
         note += " · " + "; ".join(notes)
     return {"path": out_path, "n_pages": n_pages, "chapters": chapters_meta,
@@ -932,9 +1057,11 @@ def render_pdf(chapters: list, out_path: str, meta: dict = None) -> dict:
 
 
 def _wire_glossary_links(st: _PdfState, out_path: str, notes: list) -> int:
-    """Build {source rect → glossary dest} links and apply them via PyMuPDF.
+    """Apply internal PDF links via PyMuPDF: glossary terms + the cover index.
 
-    Returns the number of links applied (0 if there is nothing to wire or the
+    Builds two sets of GOTO links — every in-text glossary term → its entry, and
+    every cover ``TocEntry`` → its chapter's first page — and applies them in one
+    pass. Returns the number of links applied (0 if there is nothing to wire or the
     post-processor is unavailable). Never raises."""
     try:
         links = []
@@ -945,6 +1072,14 @@ def _wire_glossary_links(st: _PdfState, out_path: str, notes: list) -> int:
             links.append({
                 "src_page": src["page"], "src_rect": src["rect"],
                 "dst_page": dest["page"], "dst_point": dest["point"]})
+        # Cover index → chapter first page (clickable, navigable table of contents).
+        for src in st.toc_sources:
+            dest = st.chapter_starts.get(src.get("target_id"))
+            if not dest:
+                continue
+            links.append({
+                "src_page": src["page"], "src_rect": src["rect"],
+                "dst_page": dest["page"], "dst_point": dest["point"]})
         if not links:
             return 0
         from datascience.add_pdf_internal_links import add_pdf_internal_links
@@ -952,7 +1087,7 @@ def _wire_glossary_links(st: _PdfState, out_path: str, notes: list) -> int:
         if isinstance(res, dict) and res.get("status") == "ok":
             return int(res.get("n_links") or 0)
         if isinstance(res, dict) and res.get("error"):
-            notes.append(f"glosario sin enlaces: {res.get('error')}")
+            notes.append(f"enlaces internos no aplicados: {res.get('error')}")
     except Exception as e:  # noqa: BLE001 — links are best-effort.
-        notes.append(f"glosario sin enlaces: {e}")
+        notes.append(f"enlaces internos no aplicados: {e}")
     return 0

python/functions/datascience/automatic_eda/render_pptx_impl.py

@@ -51,6 +51,12 @@ _FS_H1, _FS_H2, _FS_H3 = 20, 16, 13
 _FS_BODY, _FS_CELL, _FS_NOTE = 14, 11, 11
 _GAP = 0.12
 
+# Rasterization DPI for every embedded figure/table image. Raised from 150 to 220
+# so a viewer can zoom into a slide (or a shared picture) and read crisp detail —
+# axis labels, table cells — without pixelation. Kept moderate so the deck size
+# stays reasonable. Same value as the PDF renderer.
+_RASTER_DPI = 220
+
 
 class _PptxState:
     def __init__(self, prs, title: str):
@@ -65,6 +71,10 @@ class _PptxState:
         # Glossary wiring (mejora 6): runs to link and per-term target slide.
         self.term_runs = []           # [(key, run)]
         self.term_anchor_slide = {}   # key -> Slide (glossary entry)
+        # Clickable index (cover → chapter). toc_runs are the cover's index runs;
+        # chapter_starts maps a chapter id AND its title to its first slide.
+        self.toc_runs = []            # [(target_id, run, src_slide)]
+        self.chapter_starts = {}      # id|title -> Slide (chapter first slide)
 
 
 def _rgb(c):
@@ -309,6 +319,58 @@ def _col_widths(header, rows):
     return [_USABLE_W * w / total for w in clamped]
 
 
+# Minimal legible characters reserved per column when deciding whether a table
+# can be shown as a native (selectable) PowerPoint table. Below this width per
+# column the cells become unreadable, so the table is rasterized to a zoomable
+# high-res image instead. The 16:9 slide is wide, so more columns fit than on A5.
+_MIN_LEGIBLE_CHARS = 8
+_CELL_PAD = 0.05
+
+
+def _table_fits_as_text(header: list, rows: list) -> bool:
+    """True when the table fits the usable slide width as a readable table.
+
+    A table whose columns cannot each get a minimal legible width within the slide
+    usable width (typically many columns, e.g. a 19-column ``df.head``) is flagged
+    so it is rendered as one high-resolution image — the viewer zooms in and reads
+    every cell — instead of being squeezed unreadable. Narrow tables keep the
+    native selectable table."""
+    header = header or []
+    rows = rows or []
+    ncol = len(header) if header else (len(rows[0]) if rows else 1)
+    ncol = max(1, ncol)
+    cw = tl.avg_char_width_in(_FS_CELL)
+    min_needed = ncol * (_MIN_LEGIBLE_CHARS * cw + _CELL_PAD * 2)
+    return min_needed <= _USABLE_W
+
+
+def _table_figure_block(block):
+    """Wrap a too-wide table as a lazily-rasterized Figure (cached on the block).
+
+    Drawn once via ``render_table_as_figure`` (header shading + zebra) and embedded
+    as one high-res image scaled to fit entirely. The title/note are drawn inside
+    the image (self-describing when zoomed/shared), so no separate caption is
+    emitted. Reused for measuring and placing so keep-together stays consistent."""
+    cached = getattr(block, "_aeda_tablefig", None)
+    if cached is not None:
+        return cached
+    header = list(getattr(block, "header", []) or [])
+    rows = list(getattr(block, "rows", []) or [])
+    title = getattr(block, "title", None)
+    note = getattr(block, "note", None)
+
+    def _make():
+        from datascience.render_table_as_figure import render_table_as_figure
+        return render_table_as_figure(header, rows, title=title, note=note)
+
+    fig = model.Figure(make=_make, caption=None)
+    try:
+        block._aeda_tablefig = fig
+    except Exception:  # noqa: BLE001 — block may reject attributes; degrade.
+        pass
+    return fig
+
+
 def _row_height_in(cells, widths, fs) -> float:
     lh = tl.line_height_in(fs)
     maxlines = 1
@@ -372,11 +434,27 @@ def _style_cell(cell, fs, color, bold, fill) -> None:
 
 def _place_data_table(st: _PptxState, block, shaded_header=True,
                       key_value=False) -> None:
+    header = list(getattr(block, "header", []) or [])
+    rows = list(getattr(block, "rows", []) or [])
+    # Too many columns to be legible as a native table → render the whole table as
+    # one high-res picture, scaled to fit entirely (the viewer zooms to read it).
+    # KVTables (rendered here as a 2-column Campo/Valor table) are excluded: they
+    # always fit in width and stay as a selectable table.
+    if not key_value and not _table_fits_as_text(header, rows):
+        figblock = _table_figure_block(block)
+        data, _asp = _figure_bytes_cached(figblock)
+        if data is None:
+            _add_text(st, ["(tabla no disponible)"], _FS_NOTE, _MUTED,
+                      italic=True)
+            st.y += _GAP
+            return
+        _place_picture_bytes(st, data, None,
+                             max_h_in=getattr(figblock, "height_in", None),
+                             force_caption=False)
+        return
     title = getattr(block, "title", None)
     if title:
         _place_heading(st, model.Heading(title, level=2))
-    header = list(getattr(block, "header", []) or [])
-    rows = list(getattr(block, "rows", []) or [])
     fs = _FS_CELL
     widths = _col_widths(header, rows)
     header_h = _row_height_in(header, widths, fs) if header else 0.0
@@ -436,7 +514,7 @@ def _resolve_png(block):
     try:
         import matplotlib.pyplot as plt
         buf = io.BytesIO()
-        f.savefig(buf, format="png", dpi=150, bbox_inches="tight")
+        f.savefig(buf, format="png", dpi=_RASTER_DPI, bbox_inches="tight")
         buf.seek(0)
         return buf.read()
     except Exception:  # noqa: BLE001
@@ -483,12 +561,15 @@ def _figure_bytes_cached(block):
 
 
 def _place_picture_bytes(st: _PptxState, data: bytes, caption,
-                         max_h_in=None) -> None:
+                         max_h_in=None, force_caption=True) -> None:
     # Mejora 4 — every figure on a slide carries a visible caption/title. If the
     # block has no caption, fall back to the current section heading, then to a
-    # generic label, so no image is ever shown untitled.
-    caption = (model._safe_str(caption).strip()
-               or model._safe_str(st.last_heading).strip() or "Figura")
+    # generic label, so no image is ever shown untitled. ``force_caption=False``
+    # suppresses that fallback (used for table images, whose title is inside the
+    # picture) so no redundant caption is drawn.
+    caption = model._safe_str(caption).strip()
+    if not caption and force_caption:
+        caption = model._safe_str(st.last_heading).strip() or "Figura"
     w_px, h_px = _img_size_px(data)
     aspect = (h_px / w_px) if w_px else 0.66
     # Reserve the caption's REAL (possibly multi-line) height FIRST, then scale
@@ -496,9 +577,11 @@ def _place_picture_bytes(st: _PptxState, data: bytes, caption,
     # so its caption always fits on the SAME slide and no image is untitled.
     # cap_real = what _add_text consumes; cap_reserve adds the post-image gap and
     # a small cushion so the caption never spills to the next slide.
-    cap_lines = tl.wrap(caption, tl.chars_per_line(_USABLE_W, _FS_NOTE))
-    cap_real = tl.line_height_in(_FS_NOTE) * len(cap_lines) + 0.05
-    cap_reserve = cap_real + 0.05 + 0.10
+    cap_lines = tl.wrap(caption, tl.chars_per_line(_USABLE_W, _FS_NOTE)) \
+        if caption else []
+    cap_real = (tl.line_height_in(_FS_NOTE) * len(cap_lines) + 0.05) \
+        if cap_lines else 0.0
+    cap_reserve = (cap_real + 0.05 + 0.10) if cap_lines else 0.05
     max_h = _CONTENT_BOTTOM - _CONTENT_TOP
     # height_in hint (model.Figure/Image): cap the target height so a figure in a
     # keep-together Group shrinks to leave room for its heading and text.
@@ -517,7 +600,8 @@ def _place_picture_bytes(st: _PptxState, data: bytes, caption,
     st.slide.shapes.add_picture(io.BytesIO(data), Inches(left), Inches(st.y),
                                 width=Inches(target_w), height=Inches(target_h))
     st.y += target_h + 0.05
-    _add_text(st, cap_lines, _FS_NOTE, _MUTED, italic=True)
+    if cap_lines:
+        _add_text(st, cap_lines, _FS_NOTE, _MUTED, italic=True)
     st.y += _GAP
 
 
@@ -663,12 +747,16 @@ def _measure_kv_table(block) -> float:
 def _measure_data_table(block) -> float:
     """Faithful DataTable height — matches ``_place_data_table`` (title heading +
     wrapped header + every wrapped row + optional note). Keep in sync."""
+    header = list(getattr(block, "header", []) or [])
+    rows = list(getattr(block, "rows", []) or [])
+    # Mirror the placer: a too-wide table is drawn as one image, so its
+    # keep-together height is the image's, not the (squeezed) table layout's.
+    if not _table_fits_as_text(header, rows):
+        return _measure_figure_like(_table_figure_block(block))
     h = 0.0
     title = getattr(block, "title", None)
     if title:
         h += _measure_heading_text(title, 2)
-    header = list(getattr(block, "header", []) or [])
-    rows = list(getattr(block, "rows", []) or [])
     fs = _FS_CELL
     widths = _col_widths(header, rows)
     if header:
@@ -698,6 +786,10 @@ def _measure_block(st: _PptxState, block) -> float:
             lines = tl.wrap(getattr(block, "text", ""),
                             tl.chars_per_line(_USABLE_W, _FS_NOTE))
             return tl.line_height_in(_FS_NOTE) * len(lines) + 0.05 + _GAP
+        if kind == "toc_entry":
+            lines = tl.wrap(tl.strip_inline_md(getattr(block, "label", "")),
+                            tl.chars_per_line(_USABLE_W - 0.3, _FS_BODY)) or [""]
+            return tl.line_height_in(_FS_BODY) * len(lines) + 0.05
         if kind == "kv_table":
             return _measure_kv_table(block)
         if kind == "data_table":
@@ -810,6 +902,73 @@ def _fit_group_blocks(st: _PptxState, blocks: list, avail_full: float) -> list:
     return out
 
 
+def _fit_img(width_col: float, aspect: float, max_h: float):
+    """Scale an image to ``width_col`` then clamp to ``max_h`` keeping aspect."""
+    w = width_col
+    h = w * aspect
+    if h > max_h:
+        h = max_h
+        w = (h / aspect) if aspect else width_col
+    return w, h
+
+
+def _place_group_side_by_side(st: _PptxState, block, avail_full: float) -> bool:
+    """Place a Group's table (left ~55%) next to its figure (right ~45%).
+
+    Both the table and the figure are rasterized to high-res images and placed in
+    two columns of the SAME slide; any other blocks (e.g. a heading) render full
+    width above the pair, the rest below. Returns True on success; returns False
+    (so the caller falls back to stacking) when the group has no table+figure pair
+    or the pair cannot fit side by side on one slide. Never raises by itself."""
+    blocks = getattr(block, "blocks", []) or []
+    tbl = next((b for b in blocks
+                if getattr(b, "kind", "") in ("data_table", "kv_table")), None)
+    fig = next((b for b in blocks
+                if getattr(b, "kind", "") in ("figure", "image")), None)
+    if tbl is None or fig is None:
+        return False
+    gap_col = 0.3
+    left_w = _USABLE_W * 0.55 - gap_col / 2.0
+    right_w = _USABLE_W * 0.45 - gap_col / 2.0
+    if left_w <= 1.0 or right_w <= 1.0:
+        return False
+    tdata, tasp = _figure_bytes_cached(_table_figure_block(tbl))
+    fdata, fasp = _figure_bytes_cached(fig)
+    if not tdata or not fdata:
+        return False
+    ti, fi = blocks.index(tbl), blocks.index(fig)
+    lo = min(ti, fi)
+    lead = list(blocks[:lo])
+    rest = [b for b in blocks[lo + 1:] if b is not tbl and b is not fig]
+    lead_h = sum(_measure_block(st, b) for b in lead)
+    rest_h = sum(_measure_block(st, b) for b in rest)
+    col_max_h = avail_full - lead_h - rest_h - _GAP * 2
+    if col_max_h < 1.2:
+        return False  # not enough vertical room to put the pair side by side.
+    tw, th = _fit_img(left_w, tasp, col_max_h)
+    fw, fh = _fit_img(right_w, fasp, col_max_h)
+    band = max(th, fh)
+    needed = lead_h + band + rest_h + _GAP * 2
+    if needed > avail_full:
+        return False  # taller than a whole slide even side by side → stack.
+    if needed > _remaining(st):
+        _new_slide(st, cont=True)
+    for b in lead:
+        _PLACERS.get(getattr(b, "kind", ""), _place_note)(st, b)
+    top = st.y
+    f_left = _ML + left_w + gap_col
+    st.slide.shapes.add_picture(
+        io.BytesIO(tdata), Inches(_ML + (left_w - tw) / 2.0),
+        Inches(top + (band - th) / 2.0), width=Inches(tw), height=Inches(th))
+    st.slide.shapes.add_picture(
+        io.BytesIO(fdata), Inches(f_left + (right_w - fw) / 2.0),
+        Inches(top + (band - fh) / 2.0), width=Inches(fw), height=Inches(fh))
+    st.y = top + band + _GAP
+    for b in rest:
+        _PLACERS.get(getattr(b, "kind", ""), _place_note)(st, b)
+    return True
+
+
 def _place_group(st: _PptxState, block) -> None:
     """Render a keep-together Group: move it whole to the next slide if needed."""
     blocks = getattr(block, "blocks", []) or []
@@ -820,6 +979,14 @@ def _place_group(st: _PptxState, block) -> None:
     if getattr(block, "page_break_before", False) and st.y > _CONTENT_TOP + 1e-6:
         _new_slide(st, cont=True)
     avail_full = _CONTENT_BOTTOM - _CONTENT_TOP
+    # layout="side_by_side": try table-left / figure-right on one slide; on any
+    # reason it can't, fall through to the normal stacked keep-together below.
+    if str(getattr(block, "layout", "stack")).lower() == "side_by_side":
+        try:
+            if _place_group_side_by_side(st, block, avail_full):
+                return
+        except Exception:  # noqa: BLE001 — degrade to stacking, never abort.
+            pass
     # Trim oversized tables first (keeps the chart on the same slide), then shrink
     # the figure to share the remaining room.
     blocks = _fit_group_blocks(st, blocks, avail_full)
@@ -853,6 +1020,44 @@ def _place_glossary_entry(st: _PptxState, block) -> None:
     st.y += _GAP
 
 
+def _place_toc_entry(st: _PptxState, block) -> None:
+    """Render one clickable index line and record its run as a link source.
+
+    Drawn as a bulleted line in the accent link colour; the run is recorded in
+    ``st.toc_runs`` so it later becomes a native slide-jump to the target chapter's
+    first slide. If the target is never resolved the line still shows as plain
+    (accent) text — never cut."""
+    label = tl.strip_inline_md(getattr(block, "label", "")) or ""
+    target_id = getattr(block, "target_id", "") or ""
+    fs = _FS_BODY
+    lines = tl.wrap(label, tl.chars_per_line(_USABLE_W - 0.3, fs)) or [""]
+    lh = tl.line_height_in(fs)
+    height = lh * len(lines) + 0.05
+    _ensure(st, height)
+    box = st.slide.shapes.add_textbox(
+        Inches(_ML), Inches(st.y), Inches(_USABLE_W), Inches(height))
+    tf = box.text_frame
+    tf.word_wrap = True
+    first = True
+    link_run = None
+    for idx, ln in enumerate(lines):
+        p = tf.paragraphs[0] if first else tf.add_paragraph()
+        first = False
+        r0 = p.add_run()
+        r0.text = "•  " if idx == 0 else "   "
+        r0.font.size = Pt(fs)
+        r0.font.color.rgb = _rgb(_LINK)
+        run = p.add_run()
+        run.text = ln
+        run.font.size = Pt(fs)
+        run.font.color.rgb = _rgb(_LINK)
+        if idx == 0:
+            link_run = run
+    if target_id and link_run is not None:
+        st.toc_runs.append((target_id, link_run, st.slide))
+    st.y += height
+
+
 _PLACERS = {
     "heading": _place_heading,
     "markdown": _place_markdown,
@@ -864,6 +1069,7 @@ _PLACERS = {
     "note": _place_note,
     "group": _place_group,
     "glossary_entry": _place_glossary_entry,
+    "toc_entry": _place_toc_entry,
 }
 
 
@@ -899,6 +1105,12 @@ def render_pptx(chapters: list, out_path: str, meta: dict = None) -> dict:
             st.chapter = ch
             st.chapter_slides = 0
             _new_slide(st, cont=False)
+            # Record this chapter's first slide as a link target for the cover
+            # index (keyed by id AND title, since the cover only knows titles).
+            if ch.id:
+                st.chapter_starts[ch.id] = st.slide
+            if getattr(ch, "title", ""):
+                st.chapter_starts.setdefault(ch.title, st.slide)
             for block in ch.blocks:
                 placer = _PLACERS.get(getattr(block, "kind", ""), _place_note)
                 try:
@@ -926,7 +1138,7 @@ def render_pptx(chapters: list, out_path: str, meta: dict = None) -> dict:
 
     note = f"{n_slides} slides"
     if n_links:
-        note += f" · {n_links} enlaces de glosario"
+        note += f" · {n_links} enlaces internos"
     if notes:
         note += " · " + "; ".join(notes)
     return {"path": out_path, "n_slides": n_slides, "chapters": chapters_meta,
@@ -934,19 +1146,21 @@ def render_pptx(chapters: list, out_path: str, meta: dict = None) -> dict:
 
 
 def _wire_glossary_links(st: _PptxState, notes: list) -> int:
-    """Turn each recorded term run into a native jump to its glossary slide.
+    """Apply native slide-jumps: glossary terms + the cover index.
 
-    Returns the number of links applied. A term whose only appearance is inside
-    its own glossary entry (source slide == target slide) is skipped. Never
+    Each in-text glossary term run jumps to its glossary entry slide, and each
+    cover ``TocEntry`` run jumps to its chapter's first slide. Returns the total
+    number of links applied. A run whose target is its own slide is skipped. Never
     raises."""
-    if not st.term_runs or not st.term_anchor_slide:
+    if not (st.term_runs and st.term_anchor_slide) and not (
+            st.toc_runs and st.chapter_starts):
         return 0
-    linked = 0
     try:
         from datascience.pptx_link_run_to_slide import pptx_link_run_to_slide
     except Exception as e:  # noqa: BLE001
-        notes.append(f"glosario sin enlaces: {e}")
+        notes.append(f"enlaces internos no aplicados: {e}")
         return 0
+    linked = 0
     for key, run, src_slide in st.term_runs:
         tgt = st.term_anchor_slide.get(key)
         if tgt is None or tgt is src_slide:
@@ -956,4 +1170,14 @@ def _wire_glossary_links(st: _PptxState, notes: list) -> int:
                 linked += 1
         except Exception:  # noqa: BLE001 — links are best-effort.
             pass
+    # Cover index → chapter first slide (clickable, navigable table of contents).
+    for target_id, run, src_slide in st.toc_runs:
+        tgt = st.chapter_starts.get(target_id)
+        if tgt is None or tgt is src_slide:
+            continue
+        try:
+            if pptx_link_run_to_slide(run, src_slide, tgt):
+                linked += 1
+        except Exception:  # noqa: BLE001 — links are best-effort.
+            pass
     return linked

python/functions/datascience/automatic_eda/render_quality_test.py

@@ -0,0 +1,283 @@
+"""Golden tests for the global render-quality features (issue: eda-render-quality).
+
+Covers, with executable evidence:
+  * High DPI: every embedded figure is rasterized at 220 dpi, so a phone reader
+    can zoom in and still see crisp detail.
+  * Wide table → image: a table too wide to be legible as text (e.g. a 19-column
+    df.head) is rendered as one high-res image that scales to fit entirely, while
+    a narrow table keeps its selectable-text/native-table rendering.
+  * ``Group(layout="side_by_side")``: in PPTX the table and figure are placed in
+    two columns of the same slide; in PDF the same group stacks vertically.
+  * Backward compatibility: a Group without ``layout`` defaults to ``"stack"`` and
+    a fitting table renders exactly as before.
+
+Renderers are invoked for real; PDFs are inspected with PyMuPDF and PPTX decks
+with python-pptx.
+"""
+
+from __future__ import annotations
+
+import os
+import tempfile
+
+import matplotlib
+
+matplotlib.use("Agg")
+import matplotlib.pyplot as plt  # noqa: E402
+
+import pytest  # noqa: E402
+
+from datascience.automatic_eda import model  # noqa: E402
+from datascience.automatic_eda.render_pdf_impl import (  # noqa: E402
+    render_pdf, _RASTER_DPI as _PDF_DPI, _table_fits_as_text as _pdf_fits)
+from datascience.automatic_eda.render_pptx_impl import (  # noqa: E402
+    render_pptx, _RASTER_DPI as _PPTX_DPI, _table_fits_as_text as _pptx_fits)
+
+
+# --------------------------------------------------------------------------- #
+# Helpers.
+# --------------------------------------------------------------------------- #
+def _simple_fig():
+    """A small, real matplotlib figure for the figure blocks."""
+    fig, ax = plt.subplots(figsize=(4, 3))
+    ax.plot([0, 1, 2, 3], [1, 3, 2, 4])
+    ax.set_title("demo")
+    return fig
+
+
+def _wide_table(n_cols=19, n_rows=5):
+    header = [f"columna_{i}" for i in range(n_cols)]
+    rows = [[f"v{r}_{c}" for c in range(n_cols)] for r in range(n_rows)]
+    return model.DataTable(header=header, rows=rows, title="Primeras filas")
+
+
+def _narrow_table():
+    return model.DataTable(header=["a", "b", "c"],
+                           rows=[["1", "2", "3"], ["4", "5", "6"]],
+                           title="Tabla estrecha")
+
+
+def _chapter(blocks, cid="cap", title="Capítulo"):
+    return [model.Chapter(id=cid, title=title, version="1.0.0", blocks=blocks)]
+
+
+# --------------------------------------------------------------------------- #
+# 1) High DPI — the unit constant and a real embedded image.
+# --------------------------------------------------------------------------- #
+def test_raster_dpi_is_high_both_renderers():
+    assert _PDF_DPI >= 200, "el DPI del PDF debe ser alto (>=200)"
+    assert _PPTX_DPI >= 200, "el DPI del PPTX debe ser alto (>=200)"
+
+
+def test_pdf_embedded_figure_is_high_resolution(tmp_path):
+    fitz = pytest.importorskip("fitz")
+    out = str(tmp_path / "fig.pdf")
+    res = render_pdf(_chapter([model.Figure(make=_simple_fig, caption="demo")]),
+                     out, {"title": "T"})
+    assert res["path"] == out
+    doc = fitz.open(out)
+    try:
+        widths = []
+        for page in doc:
+            for img in page.get_images(full=True):
+                xref = img[0]
+                info = doc.extract_image(xref)
+                widths.append(info.get("width", 0))
+        assert widths, "no se incrustó ninguna imagen en el PDF"
+        # A ~4" figure rasterized at 220 dpi is ~ >850 px wide. At the old 150 dpi
+        # it would be ~600 px. The high-res threshold proves the DPI bump.
+        assert max(widths) >= 800, \
+            f"la figura embebida no es de alta resolución: {max(widths)} px"
+    finally:
+        doc.close()
+
+
+# --------------------------------------------------------------------------- #
+# 2) Wide table → image (PDF and PPTX); narrow table stays text.
+# --------------------------------------------------------------------------- #
+def test_fit_criterion_flags_wide_and_keeps_narrow():
+    wide = _wide_table()
+    narrow = _narrow_table()
+    assert not _pdf_fits(wide.header, wide.rows), \
+        "una tabla de 19 columnas debería NO caber como texto en A5"
+    assert not _pptx_fits(wide.header, wide.rows), \
+        "una tabla de 19 columnas debería NO caber como tabla nativa en 16:9"
+    assert _pdf_fits(narrow.header, narrow.rows), \
+        "una tabla de 3 columnas debería caber como texto en A5"
+    assert _pptx_fits(narrow.header, narrow.rows), \
+        "una tabla de 3 columnas debería caber como tabla nativa en 16:9"
+
+
+def test_wide_table_rendered_as_image_pdf(tmp_path):
+    fitz = pytest.importorskip("fitz")
+    out = str(tmp_path / "wide.pdf")
+    res = render_pdf(_chapter([_wide_table()]), out, {"title": "T"})
+    assert res["path"] == out
+    doc = fitz.open(out)
+    try:
+        n_images = sum(len(page.get_images(full=True)) for page in doc)
+        text = "".join(page.get_text() for page in doc)
+    finally:
+        doc.close()
+    assert n_images >= 1, "la tabla ancha no se rasterizó como imagen en el PDF"
+    # The cells are now inside the image, not selectable text. A unique cell value
+    # must therefore NOT appear as extractable text (it lives in the picture).
+    assert "v4_18" not in text, \
+        "la tabla ancha sigue como texto seleccionable (no se hizo imagen)"
+
+
+def test_narrow_table_stays_selectable_text_pdf(tmp_path):
+    fitz = pytest.importorskip("fitz")
+    out = str(tmp_path / "narrow.pdf")
+    render_pdf(_chapter([_narrow_table()]), out, {"title": "T"})
+    doc = fitz.open(out)
+    try:
+        text = "".join(page.get_text() for page in doc)
+    finally:
+        doc.close()
+    # Narrow table is selectable text: its header/cells are extractable.
+    for v in ("a", "b", "c", "1", "6"):
+        assert v in text, f"la celda '{v}' debería ser texto seleccionable"
+
+
+def test_wide_table_rendered_as_picture_pptx(tmp_path):
+    pptx = pytest.importorskip("pptx")
+    from pptx.enum.shapes import MSO_SHAPE_TYPE
+    out = str(tmp_path / "wide.pptx")
+    res = render_pptx(_chapter([_wide_table()]), out, {"title": "T"})
+    assert res["path"] == out
+    prs = pptx.Presentation(out)
+    pics = sum(1 for s in prs.slides for sh in s.shapes
+               if sh.shape_type == MSO_SHAPE_TYPE.PICTURE)
+    assert pics >= 1, "la tabla ancha no se colocó como imagen en el PPTX"
+
+
+# --------------------------------------------------------------------------- #
+# 3) Group(layout="side_by_side"): two columns in PPTX, stacked in PDF.
+# --------------------------------------------------------------------------- #
+def _side_by_side_group():
+    return model.Group(
+        blocks=[model.Heading(text="Columna X", level=2),
+                _narrow_table(),
+                model.Figure(make=_simple_fig, caption="grafico")],
+        layout="side_by_side")
+
+
+def test_side_by_side_places_two_columns_pptx(tmp_path):
+    pptx = pytest.importorskip("pptx")
+    from pptx.enum.shapes import MSO_SHAPE_TYPE
+    from pptx.util import Inches
+    out = str(tmp_path / "sbs.pptx")
+    render_pptx(_chapter([_side_by_side_group()]), out, {"title": "T"})
+    prs = pptx.Presentation(out)
+    # Find the slide that holds the pair (table image + figure image).
+    centre_emu = int(Inches(13.333 / 2.0))
+    placed = False
+    for s in prs.slides:
+        lefts = [sh.left for sh in s.shapes
+                 if sh.shape_type == MSO_SHAPE_TYPE.PICTURE
+                 and sh.left is not None]
+        if len(lefts) >= 2:
+            # one picture starts in the left half, another in the right half.
+            if min(lefts) < centre_emu and max(lefts) > centre_emu:
+                placed = True
+                break
+    assert placed, \
+        "side_by_side no colocó tabla y figura en dos columnas de la misma slide"
+
+
+def test_side_by_side_stacks_in_pdf(tmp_path):
+    fitz = pytest.importorskip("fitz")
+    out = str(tmp_path / "sbs.pdf")
+    res = render_pdf(_chapter([_side_by_side_group()]), out, {"title": "T"})
+    assert res["path"] == out and res["n_pages"] >= 1
+    doc = fitz.open(out)
+    try:
+        n_images = sum(len(page.get_images(full=True)) for page in doc)
+        text = "".join(page.get_text() for page in doc)
+    finally:
+        doc.close()
+    # PDF stacks: the narrow table stays selectable text (1 of its cells is
+    # extractable) and the figure is the single embedded image — not a 2-column
+    # pair of pictures like PPTX.
+    assert n_images == 1, "el PDF no debería usar el layout de dos imágenes"
+    assert "Columna X" in text and "1" in text, \
+        "la tabla del grupo debería seguir como texto apilado en el PDF"
+
+
+# --------------------------------------------------------------------------- #
+# 4) Backward compatibility — default layout stacks, fitting table unchanged.
+# --------------------------------------------------------------------------- #
+def test_group_default_layout_is_stack():
+    g = model.Group(blocks=[_narrow_table()])
+    assert g.layout == "stack", "el layout por defecto debe ser 'stack'"
+
+
+# --------------------------------------------------------------------------- #
+# 5) Clickable cover index ("Índice") → chapter first page/slide.
+# --------------------------------------------------------------------------- #
+def _doc_with_index():
+    portada = model.Chapter(id="portada", title="Portada", version="1.0.0",
+                            blocks=[model.Heading(text="Índice", level=2),
+                                    model.TocEntry(label="Distribuciones",
+                                                   target_id="Distribuciones")])
+    cap = model.Chapter(id="num", title="Distribuciones", version="1.0.0",
+                        blocks=[model.Markdown(text="contenido del capítulo")])
+    return [portada, cap]
+
+
+def test_cover_index_is_clickable_pdf(tmp_path):
+    fitz = pytest.importorskip("fitz")
+    out = str(tmp_path / "idx.pdf")
+    res = render_pdf(_doc_with_index(), out, {"title": "T"})
+    assert res["path"] == out
+    doc = fitz.open(out)
+    try:
+        # The cover (page 0) must carry a GOTO link jumping to a later page.
+        goto = [lk for lk in doc[0].get_links()
+                if lk.get("kind") == fitz.LINK_GOTO and lk.get("page", 0) > 0]
+    finally:
+        doc.close()
+    assert goto, "el índice de la portada no produjo enlaces clicables en el PDF"
+
+
+def test_cover_index_shows_heading_pdf(tmp_path):
+    fitz = pytest.importorskip("fitz")
+    out = str(tmp_path / "idxh.pdf")
+    render_pdf(_doc_with_index(), out, {"title": "T"})
+    doc = fitz.open(out)
+    try:
+        text = "".join(page.get_text() for page in doc)
+    finally:
+        doc.close()
+    assert "Índice" in text, "la portada no muestra el encabezado 'Índice'"
+    assert "Este informe incluye" not in text, \
+        "la portada aún muestra el texto antiguo 'Este informe incluye'"
+
+
+def test_cover_index_is_clickable_pptx(tmp_path):
+    pptx = pytest.importorskip("pptx")
+    out = str(tmp_path / "idx.pptx")
+    render_pptx(_doc_with_index(), out, {"title": "T"})
+    prs = pptx.Presentation(out)
+    cover_xml = prs.slides[0]._element.xml
+    assert "hlinksldjump" in cover_xml, \
+        "el índice de la portada no produjo un salto de slide nativo en el PPTX"
+
+
+def test_default_group_renders_like_before_pptx(tmp_path):
+    pptx = pytest.importorskip("pptx")
+    from pptx.enum.shapes import MSO_SHAPE_TYPE
+    out = str(tmp_path / "stack.pptx")
+    grp = model.Group(blocks=[model.Heading(text="Y", level=2),
+                              _narrow_table(),
+                              model.Figure(make=_simple_fig, caption="g")])
+    render_pptx(_chapter([grp]), out, {"title": "T"})
+    prs = pptx.Presentation(out)
+    # Stacked group: the narrow table is a NATIVE table (selectable), and there is
+    # exactly one picture (the figure) — not the two-image side-by-side layout.
+    n_tables = sum(1 for s in prs.slides for sh in s.shapes if sh.has_table)
+    n_pics = sum(1 for s in prs.slides for sh in s.shapes
+                 if sh.shape_type == MSO_SHAPE_TYPE.PICTURE)
+    assert n_tables >= 1, "el grupo apilado debería usar una tabla nativa"
+    assert n_pics == 1, "el grupo apilado no debería duplicar imágenes"