diff --git a/server/test/api.test.js b/server/test/api.test.js
index 6308638..6ed3221 100644
--- a/server/test/api.test.js
+++ b/server/test/api.test.js
@@ -73,6 +73,14 @@ before(async () => {
   S.groupId = (await jfetch('/api/groups', post(S.jwt, { name: 'G' }))).body.id;
   S.widgetId = (await jfetch('/api/widgets', post(S.jwt, { name: 'W', widget_type: 'clock', config: {} }))).body.id;
 
+  // layouts + zones in workspace A (user1) and workspace B (user2) - for the gap-fix
+  // assertions and the cross-tenant rejection (the is_template OR workspace_id guard).
+  const zone = (n) => ({ name: n, x_percent: 0, y_percent: 0, width_percent: 100, height_percent: 100 });
+  const layA = await jfetch('/api/layouts', post(S.jwt, { name: 'LA', zones: [zone('ZA')] }));
+  S.layoutA = layA.body.id; S.zoneA = layA.body.zones[0].id;
+  const layB = await jfetch('/api/layouts', post(S.jwt2, { name: 'LB', zones: [zone('ZB')] }));
+  S.layoutB = layB.body.id; S.zoneB = layB.body.zones[0].id;
+
   // a paired device with a known token (for the WS round-trip) - inserted into the
   // server's live DB (WAL: a second connection's commit is visible to the server).
   const db = new (require('better-sqlite3'))(path.join(DATA_DIR, 'db', 'remote_display.db'), { timeout: 5000 });
@@ -244,3 +252,63 @@ test('device WS: wrong device_token is rejected (auth-error, never registered)',
   assert.ok(got.authError, 'wrong token should emit device:auth-error');
   assert.ok(!got.registered, 'wrong token must not register');
 });
+
+// ───────────────────────── TIER 4: #92 FOLLOW-UP COVERAGE ─────────────────────────
+// The non-security gaps named in the self-review (issue #92): the gap-fix fields + the
+// cross-tenant guard (the security-relevant one), docs serving, and the token lifecycle
+// branches the suite didn't exercise.
+
+test('gap: playlist item accepts zone_id and returns it on read', async () => {
+  const created = await jfetch(`/api/playlists/${S.playlistA}/items`, post(S.jwt, { widget_id: S.widgetId, zone_id: S.zoneA }));
+  assert.equal(created.status, 201);
+  assert.equal(created.body.zone_id, S.zoneA);
+  const items = await jfetch(`/api/playlists/${S.playlistA}/items`, auth(S.jwt));
+  assert.ok(items.body.some(i => i.zone_id === S.zoneA), 'GET items must return zone_id');
+});
+test('gap: playlist item REJECTS a cross-tenant zone_id (400, is_template OR workspace_id guard)', async () => {
+  const res = await jfetch(`/api/playlists/${S.playlistA}/items`, post(S.jwt, { widget_id: S.widgetId, zone_id: S.zoneB }));
+  assert.equal(res.status, 400, 'a zone from another workspace must be rejected');
+});
+test('gap: device PUT accepts layout_id and returns it on read', async () => {
+  const put = await jfetch(`/api/devices/${S.deviceId}`, { method: 'PUT', ...auth(S.jwt), body: JSON.stringify({ layout_id: S.layoutA }) });
+  assert.equal(put.status, 200);
+  assert.equal(put.body.layout_id, S.layoutA);
+  const dev = await jfetch(`/api/devices/${S.deviceId}`, auth(S.jwt));
+  assert.equal(dev.body.layout_id, S.layoutA, 'GET device must return layout_id');
+});
+test('gap: device PUT REJECTS a cross-tenant layout_id (400)', async () => {
+  const res = await jfetch(`/api/devices/${S.deviceId}`, { method: 'PUT', ...auth(S.jwt), body: JSON.stringify({ layout_id: S.layoutB }) });
+  assert.equal(res.status, 400, 'a layout from another workspace must be rejected');
+});
+
+test('docs: /openapi.yaml serves the spec document', async () => {
+  const res = await fetch(BASE + '/openapi.yaml');
+  assert.equal(res.status, 200);
+  assert.ok((await res.text()).includes('openapi: 3.1'), 'must serve the OpenAPI document');
+});
+test('docs: /docs serves the Redoc viewer wired to the spec', async () => {
+  const res = await fetch(BASE + '/docs');
+  assert.equal(res.status, 200);
+  const html = await res.text();
+  assert.ok(html.includes('<redoc') && html.includes('/openapi.yaml'), 'must serve the Redoc page pointing at /openapi.yaml');
+});
+
+test('token-create: rejects a workspace the caller is not a member of (400)', async () => {
+  // user1 is platform_admin (resolveTenancy lets them into wsB via the header) but is NOT
+  // a member of wsB; the create endpoint checks accessContext with the platform role
+  // stripped to 'user', so it must refuse to bind a token there.
+  const res = await jfetch('/api/tokens', post(S.jwt, { name: 'x', scope: 'read' }, { 'X-Workspace-Id': S.wsB }));
+  assert.equal(res.status, 400);
+  assert.equal((await jfetch('/api/tokens', post(S.jwt, { name: 'x2', scope: 'read' }))).status, 201, 'own workspace still works');
+});
+// The must_change_password gate is middleware logic and is unit-tested with an injected
+// in-memory DB in test/apitoken-unit.test.js (cross-process DB visibility against the
+// subprocess server is unreliable for asserting that specific branch).
+test('token-auth: last_used_at is stamped on first use', async () => {
+  const created = await jfetch('/api/tokens', post(S.jwt, { name: 'lu', scope: 'read' }));
+  const before = (await jfetch('/api/tokens', auth(S.jwt))).body.find(t => t.id === created.body.id);
+  assert.equal(before.last_used_at, null, 'a fresh token has no last_used_at');
+  await jfetch('/api/playlists', auth(created.body.token)); // use it once
+  const after = (await jfetch('/api/tokens', auth(S.jwt))).body.find(t => t.id === created.body.id);
+  assert.ok(after.last_used_at, 'last_used_at is set after first use');
+});
diff --git a/server/test/apitoken-unit.test.js b/server/test/apitoken-unit.test.js
new file mode 100644
index 0000000..59aefd6
--- /dev/null
+++ b/server/test/apitoken-unit.test.js
@@ -0,0 +1,57 @@
+'use strict';
+
+// Unit tests for apiTokenAuth branches that are awkward to assert against the subprocess
+// integration server (cross-process SQLite/WAL visibility is unreliable mid-run): the
+// must_change_password gate, plus a sanity check that a normal token passes with the
+// platform role stripped. Uses the project's in-memory-DB injection pattern (inject
+// ../db/database into the require cache BEFORE requiring the middleware).
+
+const { test } = require('node:test');
+const assert = require('node:assert/strict');
+const crypto = require('node:crypto');
+const Database = require('better-sqlite3');
+
+process.env.JWT_SECRET = process.env.JWT_SECRET || 'test-secret-apitoken-unit';
+
+const db = new Database(':memory:');
+db.exec(`
+  CREATE TABLE users (
+    id TEXT PRIMARY KEY, email TEXT, name TEXT, role TEXT DEFAULT 'user',
+    auth_provider TEXT, avatar_url TEXT, plan_id TEXT, email_alerts INTEGER,
+    must_change_password INTEGER NOT NULL DEFAULT 0
+  );
+  CREATE TABLE api_tokens (
+    id TEXT PRIMARY KEY, token_hash TEXT, prefix TEXT, name TEXT, user_id TEXT,
+    workspace_id TEXT, scope TEXT, created_at INTEGER, last_used_at INTEGER, revoked_at INTEGER
+  );
+`);
+require.cache[require.resolve('../db/database')] = { id: require.resolve('../db/database'), loaded: true, exports: { db } };
+const { apiTokenAuth, hashToken } = require('../middleware/apiToken');
+
+function seedToken({ mustChange }) {
+  const uid = crypto.randomUUID();
+  db.prepare('INSERT INTO users (id, email, must_change_password) VALUES (?, ?, ?)').run(uid, uid + '@t.local', mustChange ? 1 : 0);
+  const secret = 'st_' + crypto.randomBytes(16).toString('hex');
+  db.prepare('INSERT INTO api_tokens (id, token_hash, prefix, name, user_id, workspace_id, scope) VALUES (?,?,?,?,?,?,?)')
+    .run(crypto.randomUUID(), hashToken(secret), secret.slice(0, 11), 'n', uid, 'ws-x', 'read');
+  return secret;
+}
+function runAuth(secret) {
+  return new Promise((resolve) => {
+    const req = { headers: { authorization: 'Bearer ' + secret }, query: {} };
+    const res = { statusCode: 200, status(c) { this.statusCode = c; return this; }, json() { resolve({ outcome: 'response', status: this.statusCode }); } };
+    apiTokenAuth(req, res, () => resolve({ outcome: 'next', viaToken: req.viaToken, role: req.user && req.user.role }));
+  });
+}
+
+test('apiTokenAuth: a must_change_password owner is blocked with 403', async () => {
+  const r = await runAuth(seedToken({ mustChange: true }));
+  assert.equal(r.outcome, 'response');
+  assert.equal(r.status, 403);
+});
+test('apiTokenAuth: a normal owner passes (next; viaToken set; platform role stripped to user)', async () => {
+  const r = await runAuth(seedToken({ mustChange: false }));
+  assert.equal(r.outcome, 'next');
+  assert.equal(r.viaToken, true);
+  assert.equal(r.role, 'user');
+});
diff --git a/server/test/i18n-tokens.test.js b/server/test/i18n-tokens.test.js
new file mode 100644
index 0000000..75d978d
--- /dev/null
+++ b/server/test/i18n-tokens.test.js
@@ -0,0 +1,30 @@
+'use strict';
+
+// i18n drift-guard for the public-API token UI: the apitoken.* keys must have full parity
+// across all five locales. A key added to en (or any locale) without the others fails CI,
+// so the Settings "API Tokens" UI can't ship a missing translation. No server needed.
+
+const { test } = require('node:test');
+const assert = require('node:assert/strict');
+const fs = require('node:fs');
+const path = require('node:path');
+
+const LOCALES = ['en', 'es', 'fr', 'de', 'pt'];
+const I18N_DIR = path.join(__dirname, '..', '..', 'frontend', 'js', 'i18n');
+
+function apitokenKeys(locale) {
+  const text = fs.readFileSync(path.join(I18N_DIR, locale + '.js'), 'utf8');
+  return new Set((text.match(/['"]apitoken\.[a-z_]+['"]/g) || []).map(s => s.replace(/['"]/g, '')));
+}
+
+test('i18n: apitoken.* keys have full parity across all 5 locales (drift fails CI)', () => {
+  const base = apitokenKeys('en');
+  assert.ok(base.size >= 20, `en should define the apitoken keys (found ${base.size})`);
+  for (const loc of LOCALES) {
+    const keys = apitokenKeys(loc);
+    const missing = [...base].filter(k => !keys.has(k));
+    const extra = [...keys].filter(k => !base.has(k));
+    assert.deepEqual(missing, [], `${loc}.js is missing apitoken keys present in en: ${missing.join(', ')}`);
+    assert.deepEqual(extra, [], `${loc}.js has apitoken keys not in en: ${extra.join(', ')}`);
+  }
+});