test(ui): freeze the hand-written empty states with a ratchet

Seventy-five surfaces say nothing-here-yet in a hand-written muted
paragraph instead of EmptyState. The ratchet counts them, fails on a new
copy, and fails when a site moves over until its ceiling is lowered.

src/__tests__/empty-state-ratchet.test.ts

@@ -0,0 +1,107 @@
+/**
+ * An honest no-data state goes through `EmptyState` (or `ChartEmptyState` on
+ * a chart body), UI standards §6.
+ *
+ * Seventy-five surfaces said "nothing here yet" in a hand-written muted
+ * paragraph, in five sizes and three alignments, some centred in a padded
+ * box, some a bare line under the header. This is a ratchet, not a ban: the
+ * hand-written copies that remain are counted, the ceiling below may only go
+ * down, and a new copy fails the run. The ones that stay are not list or
+ * section empty states but a field that has no value ("not recorded" in a
+ * profile row), where a centred block would be the wrong shape.
+ *
+ * Matched: a `<p>`, `<div>` or `<span>` whose class list carries
+ * `text-muted-foreground` and whose only child is `{t("<key>")}` with a last
+ * key segment that names an empty state (`empty`, `none`, `noData`,
+ * `noResults`, `notRecorded`, …; a `…Hint` key is a hint, not a state).
+ *
+ * Not matched (stated, not hidden): a message assembled from several nodes,
+ * a key built at runtime, a state without the muted colour. The guard holds
+ * the idiom, not every way to say nothing.
+ */
+import { describe, expect, it } from "vitest";
+import { readFileSync } from "node:fs";
+import { join } from "node:path";
+
+import { walkSourceFiles } from "./helpers/source-files";
+
+const SRC = join(__dirname, "..");
+
+/**
+ * The hand-written empty states that remain. Lower it when a site moves to
+ * `EmptyState`; never raise it.
+ */
+const CEILING = 75;
+
+const ELEMENT_RE =
+  /<(p|div|span)\b([^>]*?)>\s*\{t\(\s*"([a-zA-Z0-9_.]+)"[^)]*\)\}\s*<\/\1>/g;
+const EMPTY_KEY_RE =
+  /(?:^|\.)[A-Za-z0-9]*?(?:empty|Empty|none|None|noData|NoData|noResults|NoResults|notRecorded|NotRecorded|noSeries|NoSeries|noReminder|NoReminder|noMedications|noSymptoms|noTimes)[A-Za-z0-9]*$/;
+
+function findHandWrittenEmptyStates(
+  files: { path: string; source: string }[],
+): string[] {
+  const hits: string[] = [];
+  for (const { path, source } of files) {
+    for (const match of source.matchAll(ELEMENT_RE)) {
+      const [, , attrs, key] = match;
+      if (!attrs.includes("text-muted-foreground")) continue;
+      if (!EMPTY_KEY_RE.test(key) || key.endsWith("Hint")) continue;
+      hits.push(`${path}: ${key}`);
+    }
+  }
+  return hits;
+}
+
+describe("empty states go through EmptyState (ratchet)", () => {
+  const files = walkSourceFiles(SRC, { floor: 2500 })
+    .filter(
+      (p) =>
+        p.endsWith(".tsx") &&
+        (p.startsWith("components/") || p.startsWith("app/")) &&
+        !p.startsWith("components/ui/") &&
+        !p.includes("__tests__/"),
+    )
+    .map((path) => ({ path, source: readFileSync(join(SRC, path), "utf8") }));
+
+  it("walks the UI tree", () => {
+    expect(files.length).toBeGreaterThan(800);
+  });
+
+  it("adds no hand-written empty state", () => {
+    const hits = findHandWrittenEmptyStates(files);
+    expect(
+      hits.length,
+      `${hits.length} hand-written empty states, ceiling ${CEILING}. Render the new one through <EmptyState variant="plain" size="compact"> (or ChartEmptyState on a chart body).\n${hits.join("\n")}`,
+    ).toBeLessThanOrEqual(CEILING);
+  });
+
+  it("has its ceiling lowered when a site moves over", () => {
+    const hits = findHandWrittenEmptyStates(files);
+    expect(
+      hits.length,
+      `Only ${hits.length} hand-written empty states remain: lower CEILING to ${hits.length}.`,
+    ).toBe(CEILING);
+  });
+
+  it("recognises the idiom it exists to count", () => {
+    expect(
+      findHandWrittenEmptyStates([
+        {
+          path: "components/a.tsx",
+          source:
+            '<p className="text-muted-foreground text-sm">{t("admin.aiQuality.empty")}</p>',
+        },
+        {
+          path: "components/b.tsx",
+          source:
+            '<p className="text-muted-foreground text-xs">{t("cycle.sheet.emptyHint")}</p>',
+        },
+        {
+          path: "components/c.tsx",
+          source: '<EmptyState title={t("labs.detail.emptyTitle")} />',
+        },
+      ]),
+    ).toEqual(["components/a.tsx: admin.aiQuality.empty"]);
+  });
+});