diff --git a/app/igneum-app/ui/ui-ota.test.mjs b/app/igneum-app/ui/ui-ota.test.mjs
new file mode 100644
index 00000000..a19a9747
--- /dev/null
+++ b/app/igneum-app/ui/ui-ota.test.mjs
@@ -0,0 +1,49 @@
+// node --test app/igneum-app/ui/ui-ota.test.mjs (no dependencies; the pre-push gate runs it)
+// The interface over the air (docs/plans/ui-ota.md): Settings > Interface's words and the gentle reload rule.
+import { test } from 'node:test';
+import assert from 'node:assert/strict';
+import { readFileSync } from 'node:fs';
+import { fileURLToPath } from 'node:url';
+import { dirname, join } from 'node:path';
+
+const here = dirname(fileURLToPath(import.meta.url));
+const src = readFileSync(join(here, 'app.js'), 'utf8');
+const mod = { exports: {} };
+new Function('module', src)(mod);
+const V = mod.exports.View;
+
+test('the embedded interface says built in; an over-the-air one says so with its date', () => {
+ assert.deepEqual(V.interfaceWords({ embedded_version: '1.0.0', active_version: '1.0.0', source: 'embedded', confirmed: true }), { line: 'Interface 1.0.0, built in', eyebrow: 'built in', help: '' });
+ const w = V.interfaceWords({ embedded_version: '1.0.0', active_version: '1.0.1', source: 'ota', installed_at: Date.UTC(2026, 9, 7, 12) / 1000, confirmed: true });
+ assert.equal(w.line, 'Interface 1.0.1, over the air, 7 Oct 2026');
+ assert.equal(w.eyebrow, 'over the air');
+ assert.equal(w.help, 'Built in: 1.0.0.');
+ assert.equal(V.interfaceWords({}).line, '');
+ assert.equal(readFileSync(join(here, 'VERSION'), 'utf8').trim(), '1.0.0', 'the embedded interface version is three-part and in ui/VERSION');
+});
+
+test('the help line says what is pending, refused, held back by the switch, or skipped', () => {
+ assert.equal(V.interfaceWords({ embedded_version: '1.0.0', active_version: '1.0.1', source: 'ota', confirmed: false }).help, 'Waiting for this window to confirm the new interface.');
+ assert.ok(V.interfaceWords({ embedded_version: '1.0.0', active_version: '1.0.0', source: 'embedded', confirmed: true, error: 'the page did not answer within 10 s of loading it.' }).help.startsWith('The last interface over the air was refused:'));
+ assert.equal(V.interfaceWords({ embedded_version: '1.0.0', active_version: '1.0.0', source: 'embedded', confirmed: true, builtin: true, published_version: '1.0.2' }).help, 'Interface 1.0.2 is published over the air; switch this off to take it.');
+ assert.equal(V.interfaceWords({ embedded_version: '1.0.0', active_version: '1.0.0', source: 'embedded', confirmed: true, busy: true, published_version: '1.0.2' }).help, 'Interface 1.0.2 is downloading.');
+ assert.equal(V.interfaceWords({ embedded_version: '1.0.0', active_version: '1.0.0', source: 'embedded', confirmed: true, note: 'interface 1.0.2 needs engine 0.3.20 or newer (this is 0.3.19)' }).help, 'Interface 1.0.2 needs engine 0.3.20 or newer (this is 0.3.19).');
+});
+
+test('the page reloads only when the served interface changed and nobody is mid-task', () => {
+ const u = { active_version: '1.0.1' };
+ assert.equal(V.shouldReload('1.0.0', u, { phase: 'dashboard' }), true);
+ assert.equal(V.shouldReload('1.0.1', u, { phase: 'dashboard' }), false, 'same version: nothing');
+ assert.equal(V.shouldReload('', u, { phase: 'dashboard' }), false, 'a page that never pinged does not reload');
+ assert.equal(V.shouldReload('1.0.0', u, { phase: 'dashboard', typing: true }), false);
+ assert.equal(V.shouldReload('1.0.0', u, { phase: 'dashboard', sheetOpen: true }), false);
+ assert.equal(V.shouldReload('1.0.0', u, { phase: 'address' }), false, 'never mid-setup');
+ assert.equal(V.shouldReload('1.0.0', null, { phase: 'dashboard' }), false);
+});
+
+test('the page pings health once after its first paint and reports a first-paint error (the DOM block carries both)', () => {
+ assert.ok(src.includes("api('api/ui/health', {})"), 'the health ping');
+ assert.ok(src.includes("api('api/ui/health', { error: uiFirstError })"), 'the first-paint error');
+ assert.ok(src.indexOf("window.addEventListener('error'") < src.indexOf('function poll()'), 'the error listener is installed before the first poll');
+ assert.ok(!/]+src=["']https?:/.test(readFileSync(join(here, 'index.html'), 'utf8')), 'no remote script in the page');
+});
diff --git a/tools/ui-mock/server.mjs b/tools/ui-mock/server.mjs
index 0bc7e7ad..89382649 100644
--- a/tools/ui-mock/server.mjs
+++ b/tools/ui-mock/server.mjs
@@ -161,6 +161,9 @@ function stateNow() {
s.mining.found = s.mining.found.concat(extra).filter(x => t - x < 3600).sort((a, b) => a - b);
s.mining.accepted_session += extra.length; s.mining.accepted_total += extra.length; s.mining.cards[0].accepted += extra.length;
if (extra.length) s.events = [{ kind: 'block', t: extra[extra.length - 1], text: 'block accepted by the node (Apple M5 Max)' }].concat(s.events).slice(0, 40);
+ // ui-ota: the interface state (Settings > Interface); ?ui=ota shows an over-the-air bundle active
+ s.ui = { embedded_version: '1.0.0', active_version: '1.0.0', source: 'embedded', installed_at: 0, confirmed: true, published_version: '', busy: false, error: '', bad: [], builtin: false, note: '' };
+ s.settings = { ...s.settings, ui_builtin: false };
s.display_name = 'studio-mac-pro-with-a-long-name';
s.host = s.display_name;