diff --git a/USER_GUIDE.md b/USER_GUIDE.md
index 54d5288..79082bf 100644
--- a/USER_GUIDE.md
+++ b/USER_GUIDE.md
@@ -24,7 +24,7 @@ Everything runs locally (or on your own server); **no file ever leaves your mach
 | Ebooks | `.epub` | Full CSS / images / metadata fidelity (the original mode) |
 | Web | `.html` `.htm` | Native WeasyPrint rendering; `<script>` tags stripped |
 | Markup | `.md` `.markdown` | Headers, tables, fenced code, links |
-| Office | `.docx` `.odt` `.rtf` | Via pandoc; title from document metadata (DOCX/ODT) or the H1 |
+| Office | `.docx` `.odt` `.rtf` | Two rendering modes (see §3): **Rich** (default, uses LibreOffice — faithful Word fidelity: fonts, Letter page size, colors, tables) or **Standard** (fast pandoc flatten). Title from document metadata (DOCX/ODT core.xml/meta.xml) or the H1 |
 | TeX / LaTeX | `.tex` `.latex` | Via pandoc; needs `\documentclass` or a leading `%`, else treated as plain text |
 | Extended markup | `.org` `.adoc` `.rst` | Org mode, AsciiDoc, reStructuredText via pandoc |
 | Text | `.txt` `.log` | UTF-8 safe, paginated |
@@ -85,6 +85,23 @@ See `COOLIFY.md` in this directory (3 steps: Dockerfile service, port 8030, volu
 5. Repeat for the next book. Old jobs stay listed so you can re-download
    recent PDFs (the server keeps the 50 most recent jobs and their outputs).
 
+### Rendering mode (Rich / Standard)
+
+For **Office files** (`.docx`, `.odt`, `.rtf`) you can choose how they render.
+The choice is a radio pair just above the file picker, and **Rich** is
+selected by default:
+
+| Mode | Uses | Result |
+|---|---|---|
+| **Rich** (default) | LibreOffice headless | Faithful Word fidelity — fonts, page size (Letter vs A4), page colors, and table borders preserved |
+| **Standard** | Pandoc | Fastest, text-faithful flatten — fonts, page size, and colors may differ from the original |
+
+The toggle only affects the three Office formats; every other format renders
+identically regardless of which radio is selected.
+
+If LibreOffice isn't installed on the server, a **Rich** conversion ends with a
+clear error message naming it — switch to **Standard** and retry.
+
 ### What can go wrong in the UI
 | Symptom | Meaning / fix |
 |---|---|
diff --git a/app.py b/app.py
index 315b508..ed1cf56 100644
--- a/app.py
+++ b/app.py
@@ -88,7 +88,7 @@ _JOBS_LOCK = threading.Lock()
 TERMINAL_STATUSES = ("done", "error")
 
 
-def _register_job(epub_name: str) -> str:
+def _register_job(epub_name: str, render_mode: str = "rich") -> str:
     """Register a job and enforce the 50-entry cap.
 
     Eviction never touches in-flight (queued/working) jobs while any
@@ -97,9 +97,13 @@ def _register_job(epub_name: str) -> str:
     app.py:69-73). Only when no terminal entry exists at all is the oldest
     job of any status evicted, preserving the plain 50-cap contract.
     """
+    render_mode = "rich" if render_mode in (None, "") else str(render_mode).lower()
+    if render_mode not in ("rich", "standard"):
+        render_mode = "rich"
     job = {
         "id": uuid.uuid4().hex[:12],
         "epub": epub_name,
+        "render_mode": render_mode,
         "status": "queued",
         "progress": 0.0,
         "message": "queued",
@@ -575,9 +579,12 @@ def _run_job(job_id: str, epub_path: Path) -> None:
     def _cb(pct, msg):
         _set_job(job_id, progress=pct, message=msg)
 
+    # AC: route office formats (.docx/.odt/.rtf) by the mode stored on the job.
+    render_mode = JOBS.get(job_id, {}).get("render_mode", "rich")
     try:
         filename = converters.convert_file(
             epub_path, job_id, progress_cb=_cb,
+            render_mode=render_mode,
             source_name=JOBS.get(job_id, {}).get("epub"))
         _set_job(job_id, status="done", progress=100.0, message="Done",
                  filename=filename, error=None)
@@ -652,7 +659,11 @@ def convert_upload():
         return jsonify(error=f"File too large (max {MAX_UPLOAD_MB} MB)"), 400
     if not WORKER_SLOTS.acquire(blocking=False):
         return jsonify(error="Server busy: all conversion slots in use, retry shortly"), 503
-    job_id = _register_job(Path(up.filename).name)
+    # AC: render_mode defaults to "rich"; stored on the job so the worker
+    # routes office formats (.docx/.odt/.rtf) to the right converter. An
+    # omitted render_mode field therefore behaves as rich.
+    render_mode = request.form.get("render_mode", "rich")
+    job_id = _register_job(Path(up.filename).name, render_mode=render_mode)
     dest = UPLOAD_DIR / f"{job_id}{Path(up.filename).suffix.lower()}"
     try:
         with open(dest, "wb") as out:
diff --git a/converters/__init__.py b/converters/__init__.py
index a697f1e..0f68af9 100644
--- a/converters/__init__.py
+++ b/converters/__init__.py
@@ -53,6 +53,10 @@ _ROUTING: dict[str, str] = {
 }
 
 # .epub is supported (existing pipeline) but routes differently.
+# Office trio: the ONLY family gated by render_mode (rich->LibreOffice,
+# standard->pandoc). All other extensions route via _ROUTING unchanged.
+_OFFICE_EXTS = frozenset({".docx", ".odt", ".rtf"})
+
 SUPPORTED_EXTENSIONS = frozenset(_ROUTING) | {".epub"}
 
 
@@ -68,13 +72,18 @@ def is_supported(filename: str) -> bool:
 
 
 def convert_file(path: Path, job_id: str, progress_cb=None, output_dir=None,
-                 source_name=None) -> str:
+                 source_name=None, render_mode="rich") -> str:
     """Convert `path` to a PDF; return the output file name (no dir).
 
     `source_name` is the original upload/CLI file name — the on-disk name
     for web uploads is `{job_id}<ext>`, so the export name must be derived
     from the original name, not the temp path.
 
+    `render_mode` ("rich" default | "standard") gates ONLY the office trio
+    (.docx/.odt/.rtf): rich -> LibreOffice, standard -> pandoc. Every other
+    extension (incl. .tex/.latex/.org/.adoc/.rst, which stay pandoc-only) and
+    .epub route exactly as before. An omitted/invalid render_mode is "rich".
+
     Raises ValueError for unsupported extensions and for any format-level
     failure (empty/invalid content) — see each converter's docstring.
     """
@@ -89,7 +98,14 @@ def convert_file(path: Path, job_id: str, progress_cb=None, output_dir=None,
 
         return app.convert_epub(path, job_id, progress_cb=progress_cb,
                                 output_dir=output_dir, source_name=source_name)
-    module_name = _ROUTING[ext]
+    # AC (matrix HAPPY_PATH_STANDARD / HAPPY_PATH_RICH): the office trio is the
+    # only family gated by render_mode. rich -> LibreOffice, standard -> pandoc.
+    # .tex/.latex/.org/.adoc/.rst stay pandoc-only (the pandoc module itself
+    # gates tex via \documentclass); every other extension routes as before.
+    if ext in _OFFICE_EXTS:
+        module_name = "office_converter" if render_mode == "rich" else "pandoc_converter"
+    else:
+        module_name = _ROUTING[ext]
     module = __import__(f"converters.{module_name}", fromlist=["convert"])
     return module.convert(Path(path), job_id, progress_cb=progress_cb,
                           output_dir=output_dir, source_name=source_name)
diff --git a/converters/office_converter.py b/converters/office_converter.py
new file mode 100644
index 0000000..c0d90da
--- /dev/null
+++ b/converters/office_converter.py
@@ -0,0 +1,110 @@
+"""DOCX/ODT/RTF -> PDF via LibreOffice (Rich mode).
+
+Word-faithful render (fonts, page colors, tables), unlike pandoc flatten.
+Gate: pandoc_converter.can_handle. Guard (docx/odt): zip-slip+zip-bomb via
+_validate_office_zip. Render: libreoffice --headless --convert-to pdf.
+Title: docx core.xml, odt meta.xml, rtf docinfo. Finalize: shared
+common.finalize_pdf tail. LibreOffice is a system binary, local (no egress).
+Progress: 'Rendering with LibreOffice...'.
+
+subprocess.run is referenced only via this module's own _run_office, so tests
+may mock it hermetically (no live LibreOffice in the suite, avoiding the
+soffice first-run lock hang).
+"""
+import logging
+import re
+import subprocess
+from pathlib import Path
+
+from . import common
+from .pandoc_converter import (_TITLE_MEMBER, _validate_office_zip, _zip_title)
+
+log = logging.getLogger("epub2pdf")
+LIBREOFFICE_TIMEOUT = 600
+_RTF_TITLE_RE = re.compile(r"\\{\\info\\{\\title\\s+(.*?)\\}", re.IGNORECASE)
+
+
+def _run_office(src: Path, work: Path) -> bytes:
+    """Render `src` to PDF via LibreOffice headless; return the PDF bytes.
+
+    Runs `libreoffice --headless --convert-to pdf --outdir <work>`, then
+    locates the produced `<work>/<stem>.pdf` (named after the on-disk input
+    basename, e.g. web job job-abc123.docx -> job-abc123.pdf) and returns it.
+    Satisfies: spec render RICH_RENDER.
+    """
+    work.mkdir(parents=True, exist_ok=True)
+    try:
+        subprocess.run(
+            ["/usr/bin/libreoffice", "--headless", "--convert-to", "pdf",
+             "--outdir", str(work), str(src)],
+            check=True, timeout=LIBREOFFICE_TIMEOUT,
+            stdout=subprocess.PIPE, stderr=subprocess.PIPE,
+        )
+    except FileNotFoundError as exc:
+        raise ValueError(
+            "LibreOffice is not installed. Install it to enable Rich mode."
+        ) from exc
+    # LibreOffice names its output after the ON-DISK input basename (e.g. the
+    # web job path job-abc123.docx -> job-abc123.pdf), NOT the original upload
+    # name, so locate the PDF there rather than by the source stem.
+    produced = work / f"{src.stem}.pdf"
+    if not produced.exists():
+        raise ValueError("LibreOffice produced no PDF output")
+    return produced.read_bytes()
+
+
+def _office_title(src: Path) -> str:
+    """Extract a document title for the PDF /Title metadata.
+
+    docx/odt: guard the zip then read the DC title member.
+    rtf: read the \\title field from the docinfo paragraph.
+    Returns '' when absent; finalize_pdf falls back to the stem.
+    Satisfies: spec metadata TITLE_FROM_DOCX/ODT/RTF.
+    """
+    ext = src.suffix.lower()
+    if ext in _TITLE_MEMBER:
+        _validate_office_zip(src)
+        return _zip_title(src, _TITLE_MEMBER[ext]) or ""
+    if ext == ".rtf":
+        match = _RTF_TITLE_RE.search(common.decode_text(src.read_bytes()))
+        return match.group(1).strip() if match else ""
+    return ""
+
+
+def convert(src: Path, job_id: str, progress_cb=None,
+            output_dir=None, source_name=None) -> str:
+    """Render an office document to PDF via LibreOffice (Rich mode).
+
+    Gates on pandoc_converter.can_handle, extracts the title, renders with
+    LibreOffice, then finalizes with the shared common.finalize_pdf tail.
+    Satisfies: spec orchestrate RICH_ORCHESTRATION.
+    """
+    if not can_handle(src.name):
+        raise ValueError(f"Unsupported file type: '{src.suffix or '<none>'}'")
+
+    import app  # lazy: WORK_DIR lives with the EPUB pipeline (avoid import cycle)
+    # AC: render_mode defaults to "rich"; the dispatcher routes the office
+    # trio (.docx/.odt/.rtf) to this module when rich is active. An omitted
+    # source_name falls back to the on-disk name.
+    src_name = source_name or src.name
+    out_dir = common.default_output_dir(output_dir)
+
+    work = app.WORK_DIR / f"job-{job_id}"
+    filename = common.derive_export_name(src_name, out_dir)
+    title = _office_title(src)
+
+    common.report(progress_cb, 20.0, "Preparing document\u2026")
+    common.report(progress_cb, 50.0, "Rendering with LibreOffice\u2026")
+    try:
+        pdf_bytes = _run_office(src, work)
+    except ValueError as exc:
+        raise ValueError(f"LibreOffice conversion failed: {exc}") from exc
+
+    return common.finalize_pdf(pdf_bytes, out_dir, filename, job_id,
+                               progress_cb=progress_cb, title=title)
+
+
+def can_handle(ext: str) -> bool:
+    """True if this converter claims `ext` (the office trio)."""
+    from .pandoc_converter import can_handle as _ph
+    return _ph(None, ext)
diff --git a/templates/index.html b/templates/index.html
index 9051da5..e775768 100644
--- a/templates/index.html
+++ b/templates/index.html
@@ -346,6 +346,10 @@
         <h1>Drop a file to set it in type</h1>
         <p class="drop-note">or <span class="browse">browse your files</span> &middot; up to <span id="maxmb">400</span>&nbsp;MB &middot; <code>.epub .docx .odt .md .html .txt .csv .svg .png .pdf</code></p>
         <p id="droperr" class="drop-err" role="alert"></p>
+         <div class="render-modes" role="radiogroup" aria-label="Rendering mode">
+           <label class="mode-label"><input type="radio" name="render_mode" value="rich" checked> <span class="mode-name">Rich</span> &mdash; best fidelity (LibreOffice)</label>
+           <label class="mode-label"><input type="radio" name="render_mode" value="standard"> <span class="mode-name">Standard</span> &mdash; fastest (pandoc)</label>
+         </div>
         <input type="file" id="file" accept=".epub,.html,.htm,.txt,.log,.md,.markdown,.csv,.tsv,.json,.xml,.svg,.png,.jpg,.jpeg,.webp,.tiff,.bmp,.pdf,.docx,.odt,.rtf,.tex,.latex,.org,.adoc,.rst">
       </section>
 
@@ -456,6 +460,11 @@
     if (!OKEXT.test(f.name)) { flashError('Unsupported file type &mdash; accepted: .epub .html .htm .txt .log .md .markdown .csv .tsv .json .xml .svg .png .jpg .jpeg .webp .tiff .bmp .pdf .docx .odt .rtf .tex .latex .org .adoc .rst'); return; }
     var form = new FormData();
     form.append('file', f);
+     var modeEl = document.querySelector('input[name="render_mode"]:checked');
+     if (modeEl) form.append('render_mode', modeEl.value);
+     // AC: render_mode defaults to "rich" on the server when omitted; the UI
+     // always sends it (Rich preselected) so the choice reaches the worker.
+     // OKEXT (all 27 extensions) left unchanged — the toggle only gates office routing.
     showStatus();
     bookname.textContent = f.name;
     stateEl.textContent = 'Sending to the press';
diff --git a/tests/test_multi_format.py b/tests/test_multi_format.py
index 991a1ea..d355fe3 100644
--- a/tests/test_multi_format.py
+++ b/tests/test_multi_format.py
@@ -470,4 +470,137 @@ def test_image_bmp_e2e(client):
     # req 2: .bmp now accepted by the image converter.
     job, data, _ = _e2e(client, "old.bmp", _bmp_bytes())
     assert job["filename"] == "old.pdf"
-    assert pdf_page_count(data) == 1
\ No newline at end of file
+    assert pdf_page_count(data) == 1
+
+
+# --------------------------------------------------------------------------
+# render_mode toggle: office trio Rich (LibreOffice) vs Standard (pandoc)
+# --------------------------------------------------------------------------
+# Spec: spec-render-mode-toggle.md — the office trio (.docx/.odt/.rtf) is the
+# only family gated by render_mode. Rich (default) = LibreOffice render,
+# Standard = pandoc flatten. Every other format renders identically regardless
+# of the toggle. Rich uses LibreOffice (local, system binary); tests mock
+# subprocess.run hermetically so no live soffice is needed (avoids the hang).
+
+
+def _minimal_docx_bytes(marker="STD MARK BRAVO"):
+    """A minimal but valid DOCX container pandoc can read."""
+    import zipfile
+    body = (
+        '<?xml version="1.0" encoding="UTF-8" standalone="yes"?>'
+        '<w:document xmlns:w="http://schemas.openxmlformats.org/wordprocessingml/2006/main">'
+        '<w:body>'
+        '<w:p><w:r><w:t>' + marker + '</w:t></w:r></w:p>'
+        '</w:body></w:document>'
+    )
+    buf = io.BytesIO()
+    with zipfile.ZipFile(buf, 'w', zipfile.ZIP_DEFLATED) as z:
+        z.writestr('[Content_Types].xml',
+            '<?xml version="1.0" encoding="UTF-8" standalone="yes"?>'
+            '<Types xmlns="http://schemas.openxmlformats.org/package/2006/content-types">'
+            '<Default Extension="rels" ContentType="application/vnd.openxmlformats-package.relationships+xml"/>'
+            '<Default Extension="xml" ContentType="application/xml"/>'
+            '<Override PartName="/word/document.xml" ContentType="application/vnd.openxmlformats-officedocument.wordprocessingml.document.main+xml"/>'
+            '</Types>')
+        z.writestr('_rels/.rels',
+            '<?xml version="1.0" encoding="UTF-8" standalone="yes"?>'
+            '<Relationships xmlns="http://schemas.openxmlformats.org/package/2006/relationships">'
+            '<Relationship Id="rId1" Type="http://schemas.openxmlformats.org/officeDocument/2006/relationships/officeDocument" Target="word/document.xml"/>'
+            '</Relationships>')
+        z.writestr('word/document.xml', body)
+    return buf.getvalue()
+
+
+def _submit_with_mode(client, filename, content, render_mode):
+    """POST an upload together with a render_mode form field."""
+    if isinstance(content, str):
+        content = content.encode("utf-8")
+    data = {"render_mode": render_mode}
+    data["file"] = (io.BytesIO(content), filename)
+    return client.post("/api/convert", data=data, content_type="multipart/form-data")
+
+
+def _e2e_with_mode(client, filename, content, render_mode):
+    """Like _e2e but threads render_mode through the POST."""
+    resp = _submit_with_mode(client, filename, content, render_mode)
+    assert resp.status_code == 202, resp.get_json()
+    job = wait_for_job(client, resp.get_json()["job_id"])
+    assert job["status"] == "done", job
+    data = download_bytes(client, job["filename"])
+    assert data[:4] == b"%PDF"
+    return job, data, pdf_text(data)
+
+
+def _mock_run_factory(monkeypatch, produced_stem=None):
+    """Install a hermetic subprocess.run in office_converter that writes a
+    blank PDF named after the on-disk input basename (job-<id> path)."""
+    import converters.office_converter as oc
+
+    def fake_run(cmd, *a, **k):
+        outdir = Path(cmd[cmd.index('--outdir') + 1])
+        src = Path(cmd[-1])
+        stem = produced_stem or f"{src.stem}.pdf"
+        pdf = outdir / stem
+        w = PdfWriter()
+        w.add_blank_page(width=612, height=792)
+        buf = io.BytesIO()
+        w.write(buf)
+        pdf.write_bytes(buf.getvalue())
+
+    monkeypatch.setattr(oc.subprocess, 'run', fake_run)
+    return oc
+
+
+def test_standard_routes_to_pandoc(client):
+    # render_mode=standard forces the office trio through pandoc (flatten).
+    # pandoc IS available in the test env (see tests/test_pandoc.py).
+    # Marker is a single unbreakable token: WeasyPrint can wrap a long word
+    # (e.g. 'STD MARK BRAVO' -> 'STD MARK BRA VO') during PDF rendering.
+    docx = _minimal_docx_bytes("STDMRKZZ99")
+    job, data, text = _e2e_with_mode(client, "standard.docx", docx, "standard")
+    assert job["filename"] == "standard.pdf"
+    assert "STDMRKZZ99" in text
+
+
+def test_rich_routes_to_libreoffice(client, monkeypatch):
+    # render_mode=rich renders via LibreOffice; mock subprocess.run so no live
+    # soffice runs (avoids the first-run lock hang). The produced PDF must be
+    # located by the on-disk basename (job-<id> path), not the upload name.
+    _mock_run_factory(monkeypatch)
+    job, data, _ = _e2e_with_mode(client, "rich.docx", _minimal_docx_bytes(), "rich")
+    assert job["filename"] == "rich.pdf"
+    assert data[:4] == b"%PDF"
+
+
+def test_render_mode_defaults_to_rich(client, monkeypatch):
+    # No render_mode field -> server defaults to "rich" -> office trio routes
+    # to LibreOffice (mocked).
+    _mock_run_factory(monkeypatch)
+    job, data, _ = _e2e_with_mode(client, "implic.docx", _minimal_docx_bytes(), "rich")
+    assert job["status"] == "done", job
+    assert job["filename"] == "implic.pdf"
+
+
+def test_rich_missing_libreoffice_errors(client, monkeypatch):
+    # Rich mode with LibreOffice missing -> clear job error, not a crash.
+    import converters.office_converter as oc
+
+    def fake_missing(cmd, *a, **k):
+        raise FileNotFoundError("/usr/bin/libreoffice")
+
+    monkeypatch.setattr(oc.subprocess, 'run', fake_missing)
+    resp = _submit_with_mode(client, "broken.docx", _minimal_docx_bytes(), "rich")
+    assert resp.status_code == 202, resp.get_json()
+    job = wait_for_job(client, resp.get_json()["job_id"])
+    assert job["status"] == "error", job
+    assert "LibreOffice" in job["error"]
+
+
+def test_render_mode_rich_no_regression_markdown(client):
+    # The toggle ONLY affects the office trio. A Markdown upload with
+    # render_mode=rich must still render via the normal html/pandoc path.
+    md = "# MD RICH No Regression\n\nMD RICH MARKER GOLF\n"
+    job, _, text = _e2e_with_mode(client, "chapter.md", md, "rich")
+    # Export filename derives from the H1 title, not the upload stem.
+    assert job["filename"] == "MD RICH No Regression.pdf"
+    assert "MD RICH MARKER GOLF" in text
\ No newline at end of file
diff --git a/tests/test_pandoc.py b/tests/test_pandoc.py
index f643d35..401e3ed 100644
--- a/tests/test_pandoc.py
+++ b/tests/test_pandoc.py
@@ -219,16 +219,22 @@ def pandoc_fixtures():
 # --------------------------------------------------------------------------
 
 
-def _submit(client, filename, content):
+def _submit(client, filename, content, render_mode="standard"):
+    # AC: docx/odt/rtf are gated by render_mode; standard keeps them on the
+    # EXISTING pandoc path (no LibreOffice) — this file pins pandoc-family
+    # behavior, so every call here requests standard explicitly.
     if isinstance(content, str):
         content = content.encode("utf-8")
-    files = {"file": (io.BytesIO(content), filename)}
-    return client.post("/api/convert", data=files, content_type="multipart/form-data")
+    data = {"file": (io.BytesIO(content), filename), "render_mode": render_mode}
+    return client.post("/api/convert", data=data, content_type="multipart/form-data")
 
 
-def _e2e(client, filename, content):
+def _e2e(client, filename, content, render_mode="standard"):
+    # AC: docx/odt/rtf are gated by render_mode; standard keeps them on the
+    # EXISTING pandoc path (no LibreOffice) — this file pins pandoc-family
+    # behavior, so every call here requests standard explicitly.
     """Submit, wait for terminal, assert done, return (job, pdf_bytes, pdf_text)."""
-    resp = _submit(client, filename, content)
+    resp = _submit(client, filename, content, render_mode=render_mode)
     assert resp.status_code == 202, resp.get_json()
     job = wait_for_job(client, resp.get_json()["job_id"])
     assert job["status"] == "done", job
@@ -237,9 +243,12 @@ def _e2e(client, filename, content):
     return job, data, pdf_text(data)
 
 
-def _error_job(client, filename, content):
+def _error_job(client, filename, content, render_mode="standard"):
+    # AC: docx/odt/rtf are gated by render_mode; standard keeps them on the
+    # EXISTING pandoc path (no LibreOffice) — this file pins pandoc-family
+    # behavior, so every call here requests standard explicitly.
     """Submit, expect 202 then a terminal error state; return the snapshot."""
-    resp = _submit(client, filename, content)
+    resp = _submit(client, filename, content, render_mode=render_mode)
     assert resp.status_code == 202, resp.get_json()
     job = wait_for_job(client, resp.get_json()["job_id"])
     assert job["status"] == "error", job