diff --git a/tests/test_site_page_text.py b/tests/test_site_page_text.py
new file mode 100644
index 000000000..d2c07212a
--- /dev/null
+++ b/tests/test_site_page_text.py
@@ -0,0 +1,333 @@
+"""The text a page gives to whatever reads it without looking at it.
+
+A crawler, a screen reader, an assistant, a text browser and a copy read
+the words of the HTML, not the layout. The Steam Deck steps of Get the
+files read three times there, once in the prose and once per drawn layout
+glued letter to letter ("Open Konsole3Click Copy,the button bythe line"),
+a filter box read "Filter Options41 rows" and the file picker an empty
+"Setup Choose a setup". These tests read representative pages the way such
+a reader does, skipping what is `hidden`, `aria-hidden`, scripts and
+styles, and hold the page to one reading of each thing it says.
+"""
+
+from __future__ import annotations
+
+import tests  # noqa: F401  offline, scratch under tmp/, the suite's own cache
+
+import json
+import re
+import shutil
+import subprocess
+import sys
+import unittest
+from html.parser import HTMLParser
+from pathlib import Path
+
+ROOT = Path(__file__).resolve().parent.parent
+sys.path.insert(0, str(ROOT / "scripts"))
+
+import sitediagrams  # noqa: E402
+import siteentries  # noqa: E402
+import sitesteps  # noqa: E402
+from siteguides import TERMINALS  # noqa: E402
+
+WEBSITE = ROOT / "website"
+DOCS = WEBSITE / "src" / "content" / "docs"
+DIST = WEBSITE / "dist"
+PLUGIN = WEBSITE / "src" / "plugins" / "rehype-stack-tables.mjs"
+SATTERI = WEBSITE / "node_modules" / "satteri" / "dist" / "index.js"
+
+# The pages that hold each kind: the drawn steps and the picker, the
+# figures, a filter box written by the build, one by the generator above
+# a file list, one above an entry table, and the stats of a setup page.
+PAGES = ("which-pack", "wiki/first-install", "wiki/architecture", "wiki/what-are-bios-files",
+         "wiki/installer", "platforms/retrodeck", "provenance-no-intro", "explore", "index")
+
+BLOCKS = frozenset(
+    "address article aside blockquote br caption dd details dialog div dl dt fieldset figcaption "
+    "figure footer form h1 h2 h3 h4 h5 h6 header hr li main nav ol option p pre section select "
+    "summary table tbody td tfoot th thead tr ul".split())
+VOID = frozenset("area base br col embed hr img input link meta source track wbr".split())
+# What the stylesheet lays out as its own box beside the text before it:
+# the markup has to space it, a reader without the stylesheet sees no box.
+OWN_BOX = ("rb-tile-name", "rb-tile-runs", "rb-stat-label", "rb-badge", "rb-table-filter-count")
+
+
+class PageText(HTMLParser):
+    """The text of a page, as a reader without the stylesheet gets it: a
+    block starts a line, an inline element adds nothing between words.
+    Skips script, style, template, `hidden` and `aria-hidden`. A tab panel,
+    hidden until its tab is picked, is read: it is content, not chrome."""
+
+    def __init__(self, article_only: bool = False) -> None:
+        super().__init__(convert_charrefs=True)
+        self.parts: list[str] = []
+        self.stack: list[tuple[str, bool]] = []
+        self.skipping = 0
+        self.inside = not article_only
+        self.glued: list[str] = []
+
+    def _text_so_far(self) -> str:
+        return "".join(self.parts[-4:])
+
+    def handle_starttag(self, tag: str, attrs: list[tuple[str, str | None]]) -> None:
+        attr = {key: value or "" for key, value in attrs}
+        classes = attr.get("class", "").split()
+        if not self.inside:
+            self.inside = "sl-markdown-content" in classes
+            return
+        if self.skipping:
+            if tag not in VOID:
+                self.stack.append((tag, False))
+            return
+        if tag == "img":
+            self.parts.append(attr.get("alt", ""))
+            return
+        if tag in BLOCKS:
+            self.parts.append("\n")
+        if any(name in OWN_BOX for name in classes) or (tag == "code" and self.stack
+                                                         and self.stack[-1][0] == "summary"):
+            before = self._text_so_far()
+            if before and not before[-1].isspace():
+                self.glued.append(f"{before[-20:]!r} <{tag} class={' '.join(classes)!r}>")
+        if tag in VOID:
+            return
+        skip = (tag in ("script", "style", "template")
+                or ("hidden" in attr and attr.get("role") != "tabpanel")
+                or attr.get("aria-hidden") == "true")
+        self.stack.append((tag, skip))
+        self.skipping += skip
+
+    def handle_endtag(self, tag: str) -> None:
+        if tag in VOID or not self.inside:
+            return
+        while self.stack:
+            name, skip = self.stack.pop()
+            self.skipping -= skip
+            if name == tag:
+                break
+        if not self.skipping and tag in BLOCKS:
+            self.parts.append("\n")
+
+    def handle_data(self, data: str) -> None:
+        if self.inside and not self.skipping:
+            self.parts.append(data)
+
+    @property
+    def text(self) -> str:
+        return re.sub(r"\n\s*", "\n", re.sub(r"[ \t]+", " ", "".join(self.parts))).strip()
+
+
+def read(html: str, article_only: bool = False) -> PageText:
+    reader = PageText(article_only)
+    reader.feed(html)
+    reader.close()
+    return reader
+
+
+def _letters(text: str) -> str:
+    """The text without any space: the letters an SVG wrapped across text
+    nodes still spell, joined or not."""
+    return re.sub(r"\s+", "", text.replace("**", ""))
+
+
+def _sources() -> dict[str, str]:
+    found = {}
+    for page in PAGES:
+        for suffix in (".mdx", ".md"):
+            path = DOCS / f"{page}{suffix}"
+            if path.is_file():
+                found[page] = path.read_text(encoding="utf-8")
+    return found
+
+
+def _built() -> dict[str, str]:
+    found = {}
+    for page in PAGES:
+        path = DIST / ("index.html" if page == "index" else f"{page}/index.html")
+        if path.is_file():
+            found[page] = path.read_text(encoding="utf-8")
+    return found
+
+
+class PageReadsOnce:
+    """The assertions, on generated page sources (the HTML the generators
+    write, Markdown left as text) and on built pages when there are any."""
+
+    pages: dict[str, PageText]
+
+    def test_the_drawn_steps_are_not_read_again(self):
+        checked = 0
+        for name, page in self.pages.items():
+            text = _letters(page.text)
+            for tab, (title, steps) in sitesteps.STEPS.items():
+                prose = _letters(TERMINALS[tab][1])
+                with self.subTest(page=name, tab=tab):
+                    self.assertLessEqual(text.count(prose), 1)
+                    self.assertNotIn(_letters(title), text)
+                    self.assertNotIn(_letters(sitesteps.description(tab)), text)
+                    # A drawn layout repeats every caption: a caption long
+                    # enough to be told apart is read at most once, by the
+                    # prose when it says it.
+                    for step in steps:
+                        caption = _letters(step.caption)
+                        if len(caption) >= 16:
+                            checked += 1
+                            self.assertLessEqual(text.count(caption), 1, step.caption)
+        self.assertGreater(checked, 0)
+
+    def test_a_figure_says_its_words_once(self):
+        for name, page in self.pages.items():
+            text = _letters(page.text)
+            for image_id in sitediagrams.IMAGE_IDS:
+                figure = sitediagrams.figures()[image_id]
+                with self.subTest(page=name, image=image_id):
+                    self.assertLessEqual(text.count(_letters(figure.desc)), 1)
+                    self.assertLessEqual(text.count(_letters(figure.caption)), 1)
+
+    def test_no_rows_counter_glued_to_a_label(self):
+        for name, page in self.pages.items():
+            with self.subTest(page=name):
+                self.assertIsNone(re.search(r"[^\s\d,(][\d,]*\d rows\b", page.text))
+                self.assertIsNone(re.search(r"(?m)^Filter \S", page.text))
+
+    def test_no_empty_picker(self):
+        for name, page in self.pages.items():
+            with self.subTest(page=name):
+                self.assertNotIn("Choose a setup", page.text)
+
+    def test_what_sits_in_its_own_box_is_spaced(self):
+        for name, page in self.pages.items():
+            with self.subTest(page=name):
+                self.assertEqual(page.glued, [])
+
+
+class GeneratedPagesReadOnce(PageReadsOnce, unittest.TestCase):
+    @classmethod
+    def setUpClass(cls):
+        sources = _sources()
+        if "which-pack" not in sources:
+            raise unittest.SkipTest("no generated pages: run scripts/generate_site.py")
+        cls.pages = {name: read(text) for name, text in sources.items()}
+
+    def test_the_pages_hold_what_is_checked(self):
+        sources = _sources()
+        self.assertIn("rb-steps", sources["which-pack"])
+        self.assertIn('class="rb-table-filter" hidden', sources["platforms/retrodeck"])
+        self.assertIn('class="rb-table-filter" hidden', sources["provenance-no-intro"])
+        self.assertIn('class="rb-figure"', sources["wiki/architecture"])
+
+
+class BuiltPagesReadOnce(PageReadsOnce, unittest.TestCase):
+    @classmethod
+    def setUpClass(cls):
+        built = _built()
+        if "which-pack" not in built:
+            raise unittest.SkipTest("no built site")
+        cls.pages = {name: read(text, article_only=True) for name, text in built.items()}
+
+    def test_the_build_writes_the_filter_boxes_hidden(self):
+        boxes = re.findall(r'<div class="rb-table-filter"[^>]*>', _built()["wiki/installer"])
+        self.assertTrue(boxes)
+        for box in boxes:
+            self.assertIn(" hidden", box)
+
+
+class TheTwoFilterBoxesAreOne(unittest.TestCase):
+    """rehype-stack-tables.mjs writes the box above a Markdown table,
+    siteentries.filter_box above an HTML one: the same markup, so site.ts,
+    the stylesheet and every reader meet one box."""
+
+    def test_the_build_writes_what_the_generator_writes(self):
+        node = shutil.which("node")
+        if not node or not SATTERI.is_file():
+            self.skipTest("no node or no website/node_modules")
+        rows = "\n".join(f"| a{i} | b | c |" for i in range(22))
+        script = (
+            f"const {{ markdownToHtml }} = await import({json.dumps(SATTERI.as_uri())});\n"
+            f"const {{ default: stackTables }} = await import({json.dumps(PLUGIN.as_uri())});\n"
+            f"const md = {json.dumps(f'## Options{chr(10)}{chr(10)}| Flag | What | When |{chr(10)}|---|---|---|{chr(10)}{rows}{chr(10)}')};\n"
+            "console.log(markdownToHtml(md, { hastPlugins: [stackTables()] }).html);\n"
+        )
+        built = subprocess.run([node, "--input-type=module", "-e", script], capture_output=True,
+                               text=True, check=True, timeout=60).stdout
+        box = re.search(r'<div class="rb-table-filter".*?</div>', built, re.S)
+        self.assertIsNotNone(box)
+        self.assertEqual(box.group(0), siteentries.filter_box(
+            "rb-table-filter-1", "Options", ["Flag", "What", "When"], 22))
+
+    def test_a_box_reads_nothing_until_wired(self):
+        box = siteentries.filter_box("x", "files", ["File", "path"], 41)
+        self.assertEqual(read(box).text, "")
+        self.assertIn('aria-describedby="x-count"', box)
+        self.assertIn('<span id="x-count"', box)
+        self.assertIn("</label> <input", box)
+        self.assertIn('"> <span', box)
+
+    def test_the_script_shows_the_boxes(self):
+        source = (WEBSITE / "src" / "scripts" / "site.ts").read_text(encoding="utf-8")
+        self.assertIn("querySelectorAll<HTMLElement>('.rb-table-filter[hidden]')) box.hidden = false",
+                      source)
+        css = (WEBSITE / "src" / "styles" / "retrobios.css").read_text(encoding="utf-8")
+        self.assertIn(".rb-table-filter[hidden] { visibility: hidden; }", css)
+
+
+class ThePickerWaitsForItsScript(unittest.TestCase):
+    def test_hidden_until_the_setups_are_listed(self):
+        source = (WEBSITE / "src" / "components" / "FilePicker.astro").read_text(encoding="utf-8")
+        self.assertRegex(source, r'<div class="rb-picker" hidden ')
+        listed = source.index("select.add(new Option(entry.name, entry.platform));")
+        self.assertLess(listed, source.index("root.hidden = false;"))
+        self.assertIn(".rb-picker[hidden] { display: block; visibility: hidden; }", source)
+
+
+class DiagramsAreImages(unittest.TestCase):
+    """One text source per drawing: the images are alt="", the figure says
+    the words once. Each theme has its files, coloured as the page is."""
+
+    def test_no_inline_drawing_and_no_alt(self):
+        for html in [*(sitediagrams.figure_html(i) for i in sitediagrams.IMAGE_IDS),
+                     *("".join(sitesteps.steps_figure(tab)) for tab in sitesteps.STEPS)]:
+            with self.subTest(html=html[:60]):
+                self.assertNotIn("<svg", html)
+                self.assertEqual(set(re.findall(r'<img [^>]*alt="([^"]*)"', html)), {""})
+                self.assertEqual(len(re.findall(r"<picture ", html)), len(sitediagrams.THEMES))
+
+    def test_every_image_has_its_file(self):
+        files = {**sitediagrams.figure_files(), **sitesteps.steps_files()}
+        pages = [*(sitediagrams.figure_html(i) for i in sitediagrams.IMAGE_IDS),
+                 *("".join(sitesteps.steps_figure(tab)) for tab in sitesteps.STEPS)]
+        named = {url.rsplit("/", 1)[1] for html in pages
+                 for url in re.findall(r'(?:src|srcset)="([^"]+)"', html)}
+        self.assertEqual(named, set(files))
+
+    def test_the_figure_says_its_desc_once(self):
+        for image_id in sitediagrams.IMAGE_IDS:
+            figure = sitediagrams.figures()[image_id]
+            with self.subTest(image=image_id):
+                text = read(sitediagrams.figure_html(image_id)).text
+                self.assertEqual(text.count(figure.desc), 1)
+                self.assertIn(figure.caption, text)
+
+    def test_the_theme_colours_are_the_stylesheet_tokens(self):
+        css = (WEBSITE / "src" / "styles" / "retrobios.css").read_text(encoding="utf-8")
+        light_at = css.index(":root[data-theme='light'] {")
+        blocks = {"dark": css[css.index(":root {"):light_at], "light": css[light_at:]}
+        tokens = {"fill": "--rb-diagram-fill", "stroke": "--rb-diagram-stroke",
+                  "accent": "--rb-diagram-accent", "muted": "--rb-text-secondary"}
+        for theme, block in blocks.items():
+            for key, token in tokens.items():
+                with self.subTest(theme=theme, token=token):
+                    value = re.search(rf"{token}:\s*(#[0-9a-f]+);", block).group(1)
+                    self.assertEqual(sitediagrams.THEMES[theme][key], value)
+
+    def test_a_file_carries_its_theme(self):
+        for name, text in sitesteps.steps_files().items():
+            theme = name.rsplit("-", 1)[1].removesuffix(".svg")
+            with self.subTest(file=name):
+                self.assertIn(f".rb-d-box{{fill:{sitediagrams.THEMES[theme]['fill']}", text)
+                self.assertTrue(text.startswith("<svg "))
+
+
+if __name__ == "__main__":
+    unittest.main()
diff --git a/wiki/testing-guide.md b/wiki/testing-guide.md
index a94265a99..e50b9e1a2 100644
--- a/wiki/testing-guide.md
+++ b/wiki/testing-guide.md
@@ -69,7 +69,7 @@ Every module in `tests/`, by the area it guards.
 | Pack probe | the cores a platform runs for a system, staging grown to a fixed point, runs mapped to pack and manifest entries, the line and its schema, the probe lock per run, that no page shows its lines. One class builds a real pack narrowed to PlayStation and lays it out both ways, from the archive and with `install.py --dest`, and skips without the collection | `test_pack_probe` |
 | Automation runner, disk cleanup, asset sync and bit-flip repair | fake jobs, git repositories with a bare origin and session worktrees, a committed file with one bit flipped, canned CI runs in place of `gh` | `test_autorun` |
 | Truth and native export | synthetic + cached originals | `test_export_counts`, `test_export_native_layer`, `test_export_report`, `test_exporters`, `test_truth_data_dir_readers`, `test_truth_diff`, `test_truth_layout` |
-| Scrapers, upstream and provenance | inline sources, synthetic | `test_batocera_md5_list`, `test_check_freshness`, `test_cited_lines`, `test_contributing_text`, `test_coverage_cache`, `test_data_dir_refs`, `test_dataclass_defaults`, `test_dedup`, `test_doc_pages`, `test_doc_surfaces`, `test_elec_scrapers`, `test_fbneo_parser`, `test_find_pinned_revision`, `test_hash_merge`, `test_launchers`, `test_launchers_amberelec`, `test_launchers_emudeck`, `test_launchers_emuelec`, `test_launchers_knulli`, `test_launchers_recalbox`, `test_launchers_retrobat`, `test_launchers_retrodeck`, `test_launchers_retropie`, `test_launchers_rocknix`, `test_mame_devices`, `test_mame_parser`, `test_mame_ref_audit`, `test_optional_dependencies`, `test_pin_build`, `test_profile_sync`, `test_prose_style`, `test_provenance`, `test_refresh_data_dirs`, `test_refresh_failures`, `test_refresh_stale`, `test_retired_files`, `test_retrodeck_scraper_errors`, `test_romset_recipes`, `test_schema_semantic_gate`, `test_scraper_contract`, `test_site_agents`, `test_site_arcade_boards`, `test_site_availability`, `test_site_bootstrap`, `test_site_built_gate`, `test_site_components`, `test_site_console_folders`, `test_site_content_data`, `test_site_copy`, `test_site_cores`, `test_site_css`, `test_site_demo`, `test_site_density_cards`, `test_site_emulator_page`, `test_site_emulators`, `test_site_entry`, `test_site_entry_tables`, `test_site_exports`, `test_site_freshness`, `test_site_funnel`, `test_site_images`, `test_site_inputs`, `test_site_insights`, `test_site_integration`, `test_site_nav`, `test_site_picker`, `test_site_platform_density`, `test_site_platform_hashes`, `test_site_privacy`, `test_site_pronouns`, `test_site_reference`, `test_site_render`, `test_site_search`, `test_site_steps`, `test_site_system_links`, `test_site_system_names`, `test_site_system_sections`, `test_site_systems`, `test_site_validation`, `test_site_weight`, `test_site_wiki`, `test_site_write`, `test_source_ref_targets`, `test_upstream`, `test_upstream_index`, `test_validate_pr`, `test_validate_pr_flow`, `test_validate_pr_hashes`, `test_version_basis`, `test_workflow_paths` |
+| Scrapers, upstream and provenance | inline sources, synthetic | `test_batocera_md5_list`, `test_check_freshness`, `test_cited_lines`, `test_contributing_text`, `test_coverage_cache`, `test_data_dir_refs`, `test_dataclass_defaults`, `test_dedup`, `test_doc_pages`, `test_doc_surfaces`, `test_elec_scrapers`, `test_fbneo_parser`, `test_find_pinned_revision`, `test_hash_merge`, `test_launchers`, `test_launchers_amberelec`, `test_launchers_emudeck`, `test_launchers_emuelec`, `test_launchers_knulli`, `test_launchers_recalbox`, `test_launchers_retrobat`, `test_launchers_retrodeck`, `test_launchers_retropie`, `test_launchers_rocknix`, `test_mame_devices`, `test_mame_parser`, `test_mame_ref_audit`, `test_optional_dependencies`, `test_pin_build`, `test_profile_sync`, `test_prose_style`, `test_provenance`, `test_refresh_data_dirs`, `test_refresh_failures`, `test_refresh_stale`, `test_retired_files`, `test_retrodeck_scraper_errors`, `test_romset_recipes`, `test_schema_semantic_gate`, `test_scraper_contract`, `test_site_agents`, `test_site_arcade_boards`, `test_site_availability`, `test_site_bootstrap`, `test_site_built_gate`, `test_site_components`, `test_site_console_folders`, `test_site_content_data`, `test_site_copy`, `test_site_cores`, `test_site_css`, `test_site_demo`, `test_site_density_cards`, `test_site_emulator_page`, `test_site_emulators`, `test_site_entry`, `test_site_entry_tables`, `test_site_exports`, `test_site_freshness`, `test_site_funnel`, `test_site_images`, `test_site_inputs`, `test_site_insights`, `test_site_integration`, `test_site_nav`, `test_site_page_text`, `test_site_picker`, `test_site_platform_density`, `test_site_platform_hashes`, `test_site_privacy`, `test_site_pronouns`, `test_site_reference`, `test_site_render`, `test_site_search`, `test_site_steps`, `test_site_system_links`, `test_site_system_names`, `test_site_system_sections`, `test_site_systems`, `test_site_validation`, `test_site_weight`, `test_site_wiki`, `test_site_write`, `test_source_ref_targets`, `test_upstream`, `test_upstream_index`, `test_validate_pr`, `test_validate_pr_flow`, `test_validate_pr_hashes`, `test_version_basis`, `test_workflow_paths` |
 | Games on the card | small DATs, listxml and setup sources, a fake fetcher, fixture install lists, and the committed data against its schemas | `test_arcade_parents`, `test_game_catalogs`, `test_game_headers`, `test_game_regions`, `test_games_index`, `test_romfolders_card`, `test_romfolders_es` |
 
 ## Test architecture