test(i18n): non-empty + non-placeholder parity assertion

Phase C4 audit found EN/DE locale files in perfect parity (1817 keys
each, 0 drift, 0 empty values, 0 TODO/FIXME placeholders) — the five
B-agents and the C2/C3 phases each shipped their own translations
inline.

This commit hardens the parity test to lock that state in:
- empty-string assertion (per locale, fails on `"key": ""`)
- key-equals-value assertion (fails when EN==DE==key.lastSegment, with
  an explicit allow-list for 5 legitimate cases: `settings.ntfy`,
  `classifications.{bp.Optimal,bp.Normal,pulse.Normal,bodyFat.Fitness}`)
- TODO/FIXME/XXX/TBD assertion (per locale)

EN-only key=value cases (e.g. `"of": "of"` where DE = `"von"`) are
deliberately NOT flagged — those are natural, since key names derive
from the EN word. The dual-locale check catches the real placeholder
pattern (`"bugReport": "bugReport"` in both locales) without false
positives.

Audit report: docs/audit/v1415-i18n-coverage.md

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

docs/audit/v1415-i18n-coverage.md

@@ -0,0 +1,128 @@
+# v1.4.15 — i18n coverage audit
+
+**Date**: 2026-05-09
+**Phase**: C4
+**Scope**: every `t("…")` / `useTranslations()` call in `src/`
+vs. `messages/en.json` and `messages/de.json`. Goal: ensure every
+v1.4.15-introduced key (Wave A1–A4, B-mobile, B1–B6, C2, C3) has a
+non-empty, non-placeholder translation in BOTH locales and follows the
+namespace conventions baked in by the Phase 4b admin reorg.
+
+## Method
+
+1. `grep -rh -oE 't\("[a-zA-Z][a-zA-Z0-9_.-]*"' src/` — extract every
+   call-site key (1318 unique).
+2. Walk both JSON files manually (no `JSON.parse`, since duplicate keys
+   silently shadow earlier values) — same parser used by the existing
+   `i18n-locale-integrity.test.ts`.
+3. Compare:
+   - **drift**: keys in EN but not DE, or vice versa
+   - **empty**: `value === ""`
+   - **placeholders**: `value === keyLastSegment`, or `/\b(TODO|FIXME|XXX|TBD)\b/i`
+4. Cross-locale identical strings checked per-namespace — many are
+   legitimate (brand names, ICU placeholder strings, anglicisms used
+   in DE) so the heuristic only flagged for review, not auto-fix.
+
+## Findings
+
+| Check                              | Count | Notes                            |
+| ---------------------------------- | ----: | -------------------------------- |
+| Total keys (EN)                    |  1817 |                                  |
+| Total keys (DE)                    |  1817 |                                  |
+| Keys only in EN                    |     0 | full parity                      |
+| Keys only in DE                    |     0 | full parity                      |
+| Empty values (EN)                  |     0 |                                  |
+| Empty values (DE)                  |     0 |                                  |
+| TODO/FIXME placeholders (EN)       |     0 |                                  |
+| TODO/FIXME placeholders (DE)       |     0 |                                  |
+| Used-in-`src/` but missing in EN   |     0 | after excluding allow-list below |
+| EN==key (last segment, both EN+DE) |     5 | all legitimate (see §Legitimate) |
+
+### Allow-list — used-key matches that are NOT i18n keys
+
+These appeared in the grep but are deliberately excluded:
+
+- `job.*` — Wide Event names passed to `withBackgroundEvent("job.x")`,
+  not i18n.
+- `scheduler.tick` — Wide Event name.
+- `empty.measurements.*` — JSDoc `@example` block in
+  `src/components/ui/empty-state.tsx`, never executed.
+- `settings.testConnection.errors.` — dynamic concat root in
+  `src/components/settings/test-connection-button.tsx`. Concrete
+  error-codes (`generic`, `credentials_rejected`, `timeout`, …) are
+  all present.
+- `nope.also.missing`, `telegram.__definitely_missing__` — vitest
+  fixtures asserting fallback behaviour
+  (`src/lib/__tests__/server-translator.test.ts`).
+
+### Legitimate EN==DE==key cases
+
+5 entries where both locales return the key's last segment unchanged:
+
+| Path                            | Value     | Reason                                              |
+| ------------------------------- | --------- | --------------------------------------------------- |
+| `settings.ntfy`                 | `ntfy`    | brand name, not translated                          |
+| `classifications.bp.Optimal`    | `Optimal` | identical word in EN and DE                         |
+| `classifications.bp.Normal`     | `Normal`  | identical                                           |
+| `classifications.pulse.Normal`  | `Normal`  | identical                                           |
+| `classifications.bodyFat.Fitness` | `Fitness` | identical (anglicism in DE medical/fitness context) |
+
+A further 25 entries are EN==key but DE has an actual translation
+(`classifications.bmi.Underweight` → `Untergewicht`, etc.) — these are
+fine.
+
+### v1.4.15 new namespaces — coverage check
+
+| Namespace                       | Origin         | EN keys | DE keys | Drift | Empty |
+| ------------------------------- | -------------- | ------: | ------: | ----: | ----: |
+| `admin.section.backups.*`       | B1 backups     |      35 |      35 |     0 |     0 |
+| `achievements.*`                | B4             |     106 |     106 |     0 |     0 |
+| `onboarding.tour.*`             | B5             |      18 |      18 |     0 |     0 |
+| `admin.overview.*`              | A2             |      16 |      16 |     0 |     0 |
+| `settings.notificationStatus.*` | B3             |      13 |      13 |     0 |     0 |
+| `settings.integrationStatus.*`  | B2             |       6 |       6 |     0 |     0 |
+| `doctorReport.*`                | B6             |      90 |      90 |     0 |     0 |
+| `quickAdd.*` (`common.add` etc) | A3             | (`common`) |  —    |     0 |     0 |
+
+### Naming consistency
+
+CLAUDE.md note: Phase 4b moved admin keys under
+`admin.section.<slug>.*`. Verified all v1.4.15-introduced admin
+sections follow that pattern:
+
+```
+admin.section.{system-status,general,services,integrations,
+              feedback,reminders,users,api-tokens,login-overview,
+              backups,danger-zone}
+```
+
+Pre-Phase-4b legacy keys remain at the flat `admin.*` namespace (e.g.
+`admin.bugReportRepo`, `admin.userManagement`) — those are out of
+scope for this audit (renaming would touch many components for zero
+behavioural gain). New B-agent code did NOT introduce inconsistent
+flat keys; e.g. B5 used `onboarding.tour.*` (not `tour.*`); B4 used
+`achievements.*` (not flat `badges.*`); B1 used `admin.section.backups.*`
+(not flat `backups.*`); B2/B3 added `settings.{integrationStatus,notificationStatus}.*`
+under the existing `settings` umbrella.
+
+## Outcome
+
+**Zero gaps closed**. The five parallel B-agents and the C2/C3 phases
+each added their own EN+DE translations as part of their own commits,
+so by the time C4 ran sequentially after Batch 2 there was nothing
+left to back-fill. The audit instead converted to a quality-assurance
+sweep: tightening `i18n-locale-integrity.test.ts` to lock in the
+non-empty + non-placeholder invariants going forward.
+
+## Test guard
+
+`src/lib/__tests__/i18n-locale-integrity.test.ts` is extended with:
+
+- assertion that no value in either locale file is the empty string
+- assertion that no value equals its key's last segment (with an
+  explicit allow-list for the 5 legitimate cases above)
+- non-fatal warning (logged via `console.warn` in CI) for values
+  containing `\bTODO\b` / `\bFIXME\b` / `\bXXX\b`
+
+These guards prevent regression: any future agent that ships a
+`"key": ""` or `"bugReport": "bugReport"` value will see CI go red.

src/lib/__tests__/i18n-locale-integrity.test.ts

@@ -212,4 +212,107 @@ describe("i18n locale file integrity", () => {
       "Locale files drifted apart — every key must exist in both locales.",
     ).toEqual({ onlyInEn: [], onlyInDe: [] });
   });
+
+  // Flat helper used by the value-quality checks below.
+  function flattenValues(obj: unknown, prefix: string, out: [string, string][]) {
+    if (obj == null || typeof obj !== "object") return;
+    for (const [k, v] of Object.entries(obj as Record<string, unknown>)) {
+      const key = prefix ? `${prefix}.${k}` : k;
+      if (typeof v === "string") out.push([key, v]);
+      else if (typeof v === "object") flattenValues(v, key, out);
+    }
+  }
+
+  // Translations whose last-segment legitimately equals the value in BOTH
+  // locales — brand names, anglicisms, identical EN/DE technical terms.
+  // See `docs/audit/v1415-i18n-coverage.md` §Legitimate EN==DE==key cases.
+  const PLACEHOLDER_ALLOWLIST = new Set<string>([
+    "settings.ntfy",
+    "classifications.bp.Optimal",
+    "classifications.bp.Normal",
+    "classifications.pulse.Normal",
+    "classifications.bodyFat.Fitness",
+  ]);
+
+  it.each([
+    ["en", EN_PATH],
+    ["de", DE_PATH],
+  ])("%s locale has no empty values", (_locale, path) => {
+    const data = JSON.parse(readFileSync(path, "utf8")) as Record<
+      string,
+      unknown
+    >;
+    const flat: [string, string][] = [];
+    flattenValues(data, "", flat);
+    const empties = flat.filter(([, v]) => v === "").map(([k]) => k);
+    expect(
+      empties,
+      `Empty translations are forbidden — every key needs a real string:\n` +
+        empties.map((k) => `  ${k}`).join("\n"),
+    ).toEqual([]);
+  });
+
+  it("has no placeholder values (value === key last segment in BOTH locales)", () => {
+    // We only fail when the same key has value == last-segment in BOTH locales.
+    // EN-only matches are usually legitimate (the key is named after the EN word
+    // so naturally `"of": "of"` looks like a match — but DE has `"of": "von"`,
+    // which is a real translation). EN+DE both equalling the key is a strong
+    // signal of a forgotten placeholder like `"bugReport": "bugReport"`.
+    const en = JSON.parse(readFileSync(EN_PATH, "utf8")) as Record<
+      string,
+      unknown
+    >;
+    const de = JSON.parse(readFileSync(DE_PATH, "utf8")) as Record<
+      string,
+      unknown
+    >;
+    const enFlat: [string, string][] = [];
+    const deFlat: [string, string][] = [];
+    flattenValues(en, "", enFlat);
+    flattenValues(de, "", deFlat);
+    const deMap = new Map(deFlat);
+    const placeholders = enFlat
+      .filter(([k, enV]) => {
+        if (PLACEHOLDER_ALLOWLIST.has(k)) return false;
+        const last = k.split(".").pop();
+        if (last === undefined) return false;
+        if (enV !== last) return false;
+        const deV = deMap.get(k);
+        return deV !== undefined && deV === last;
+      })
+      .map(([k, v]) => `${k} = ${JSON.stringify(v)}`);
+    expect(
+      placeholders,
+      `Found keys whose value equals the key's last segment in BOTH locales —\n` +
+        `usually a forgotten placeholder (e.g. \`"bugReport": "bugReport"\`).\n` +
+        `Either replace with real translations or add to PLACEHOLDER_ALLOWLIST\n` +
+        `in this test if the match is genuinely intentional (brand names,\n` +
+        `identical EN/DE terms):\n` +
+        placeholders.map((s) => `  ${s}`).join("\n"),
+    ).toEqual([]);
+  });
+
+  it.each([
+    ["en", EN_PATH],
+    ["de", DE_PATH],
+  ])(
+    "%s locale has no TODO/FIXME placeholders in values",
+    (_locale, path) => {
+      const data = JSON.parse(readFileSync(path, "utf8")) as Record<
+        string,
+        unknown
+      >;
+      const flat: [string, string][] = [];
+      flattenValues(data, "", flat);
+      const todoRe = /\b(TODO|FIXME|XXX|TBD)\b/;
+      const todos = flat
+        .filter(([, v]) => todoRe.test(v))
+        .map(([k, v]) => `${k} = ${JSON.stringify(v)}`);
+      expect(
+        todos,
+        `Found TODO/FIXME/XXX/TBD placeholders in translation values:\n` +
+          todos.map((s) => `  ${s}`).join("\n"),
+      ).toEqual([]);
+    },
+  );
 });