refactor: split the per-system platform sections

generate_platform_page reached complexity 49, most of it in the block
rendering one collapsible section per system: each file shows a
different set of hashes, sizes and provenance depending on what the
platform declares. That block is now its own function and the caller
sits at 28. All 534 pages identical apart from timestamps.

scripts/generate_site.py

@@ -1498,6 +1498,88 @@ def generate_platform_index(coverages: dict, registry: dict | None = None) -> st
     return "\n".join(lines) + "\n"
 
 
+def _render_platform_systems(
+    by_system: dict, config_files: dict, emulator_files: dict
+) -> list[str]:
+    """One collapsible block per system, listing every file it needs.
+
+    Split out of generate_platform_page: the block is most of that
+    function's branching, since each file renders a different set of
+    hashes, sizes and provenance depending on what the platform declares.
+    """
+    lines: list[str] = []
+    # Per-system detail sections (collapsible for large platforms)
+    use_collapsible = len(by_system) > 10
+
+    for sys_id, files in sorted(by_system.items()):
+        ok_count = sum(1 for f in files if f["status"] == "ok")
+        total = len(files)
+
+        sys_emus = []
+        if emulator_files:
+            for emu_name, emu_data in emulator_files.items():
+                if sys_id in emu_data.get("systems", set()):
+                    sys_emus.append(emu_name)
+
+        sys_link = _system_link(sys_id, "../")
+
+        anchor = sys_id.replace(" ", "-")
+        if use_collapsible:
+            status_tag = "OK" if ok_count == total else f"{total - ok_count} issues"
+            lines.append(f'<a id="{anchor}"></a>')
+            lines.append(f'??? note "{sys_id} ({ok_count}/{total} - {status_tag})"')
+            lines.append("")
+            pad = "    "
+        else:
+            lines.append(f"## {sys_link}")
+            lines.append("")
+            pad = ""
+
+        lines.append(f"{pad}{ok_count}/{total} files verified")
+        if sys_emus:
+            emu_links = ", ".join(_emulator_link(e, "../") for e in sorted(sys_emus))
+            lines.append(f"{pad}Emulators: {emu_links}")
+        lines.append("")
+
+        # File listing
+        for f in sorted(files, key=lambda x: x["name"]):
+            status = f["status"]
+            fname = f["name"]
+            cfg_entry = config_files.get(fname, {})
+            sha1 = cfg_entry.get("sha1", f.get("sha1", ""))
+            md5 = cfg_entry.get("md5", f.get("expected_md5", ""))
+            size = cfg_entry.get("size", f.get("size", 0))
+
+            if status == "ok":
+                status_display = "OK"
+            elif status == "untested":
+                reason = f.get("reason", "")
+                status_display = f"untested: {reason}" if reason else "untested"
+            elif status == "missing":
+                status_display = "**missing**"
+            else:
+                status_display = status
+
+            size_str = _fmt_size(size) if size else ""
+            details = [status_display]
+            if size_str:
+                details.append(size_str)
+
+            lines.append(f"{pad}- `{fname}` - {', '.join(details)}")
+            # Show full hashes on a sub-line (useful for copy-paste)
+            if sha1 or md5:
+                hash_parts = []
+                if sha1:
+                    hash_parts.append(f"SHA1: `{sha1}`")
+                if md5:
+                    hash_parts.append(f"MD5: `{md5}`")
+                lines.append(f"{pad}    {' | '.join(hash_parts)}")
+
+        lines.append("")
+
+    return lines
+
+
 def generate_platform_page(
     name: str,
     cov: dict,
@@ -1650,74 +1732,9 @@ def generate_platform_page(
         )
     lines.append("")
 
-    # Per-system detail sections (collapsible for large platforms)
-    use_collapsible = len(by_system) > 10
-
-    for sys_id, files in sorted(by_system.items()):
-        ok_count = sum(1 for f in files if f["status"] == "ok")
-        total = len(files)
-
-        sys_emus = []
-        if emulator_files:
-            for emu_name, emu_data in emulator_files.items():
-                if sys_id in emu_data.get("systems", set()):
-                    sys_emus.append(emu_name)
-
-        sys_link = _system_link(sys_id, "../")
-
-        anchor = sys_id.replace(" ", "-")
-        if use_collapsible:
-            status_tag = "OK" if ok_count == total else f"{total - ok_count} issues"
-            lines.append(f'<a id="{anchor}"></a>')
-            lines.append(f'??? note "{sys_id} ({ok_count}/{total} - {status_tag})"')
-            lines.append("")
-            pad = "    "
-        else:
-            lines.append(f"## {sys_link}")
-            lines.append("")
-            pad = ""
-
-        lines.append(f"{pad}{ok_count}/{total} files verified")
-        if sys_emus:
-            emu_links = ", ".join(_emulator_link(e, "../") for e in sorted(sys_emus))
-            lines.append(f"{pad}Emulators: {emu_links}")
-        lines.append("")
-
-        # File listing
-        for f in sorted(files, key=lambda x: x["name"]):
-            status = f["status"]
-            fname = f["name"]
-            cfg_entry = config_files.get(fname, {})
-            sha1 = cfg_entry.get("sha1", f.get("sha1", ""))
-            md5 = cfg_entry.get("md5", f.get("expected_md5", ""))
-            size = cfg_entry.get("size", f.get("size", 0))
-
-            if status == "ok":
-                status_display = "OK"
-            elif status == "untested":
-                reason = f.get("reason", "")
-                status_display = f"untested: {reason}" if reason else "untested"
-            elif status == "missing":
-                status_display = "**missing**"
-            else:
-                status_display = status
-
-            size_str = _fmt_size(size) if size else ""
-            details = [status_display]
-            if size_str:
-                details.append(size_str)
-
-            lines.append(f"{pad}- `{fname}` - {', '.join(details)}")
-            # Show full hashes on a sub-line (useful for copy-paste)
-            if sha1 or md5:
-                hash_parts = []
-                if sha1:
-                    hash_parts.append(f"SHA1: `{sha1}`")
-                if md5:
-                    hash_parts.append(f"MD5: `{md5}`")
-                lines.append(f"{pad}    {' | '.join(hash_parts)}")
-
-        lines.append("")
+    lines.extend(
+        _render_platform_systems(by_system, config_files, emulator_files)
+    )
 
     lines.append(f"*Generated on {_timestamp()}*")
     return "\n".join(lines) + "\n"