feat: add optional Laya engine mode for grouping and language detection (#12)

Add a languageDetectionMode setting (algo | laya | laya+algo) exposed
in Settings with three engine choices. When Laya is enabled, a laya
service (Dockerfile.laya, optional compose profile, models stored
outside the repo under ./data/models/laya) can be started, with model
download and deletion from the UI via /laya routes to manage disk
space. Add a channelLanguageFusion service combining Laya results
with the existing algorithm, and wire detection mode through
grouping, channel list and player. Cover engine selection, fusion
and laya service behavior with tests.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

test/channelLanguageFusion.test.js

@@ -0,0 +1,41 @@
+const test = require('node:test');
+const assert = require('node:assert/strict');
+const fusion = require('../public/js/services/channelLanguageFusion.js');
+
+const algo = {
+    language: { code: 'fr', label: 'French', confidence: 70, status: 'medium' },
+    languageScores: { fr: 70, en: 30 },
+    languageEvidence: [{ code: 'fr', weight: 60, type: 'name-prefix', value: 'FR' }]
+};
+
+test('Laya-only mode maps backend confidence and language', () => {
+    const result = fusion.applyLanguageMode(algo, { language: 'en', confidence: 0.88 }, 'laya');
+    assert.deepEqual(result.language, { code: 'en', label: 'English', confidence: 88, status: 'high' });
+    assert.equal(result.languageEvidence[0].type, 'laya');
+});
+
+test('hybrid mode combines Laya and algorithm evidence', () => {
+    const result = fusion.applyLanguageMode(algo, { language: 'en', confidence: 0.9 }, 'hybrid');
+    assert.equal(result.language.code, 'en');
+    assert.ok(result.languageScores.en > result.languageScores.fr);
+    assert.deepEqual(result.languageEvidence.map(item => item.type), ['name-prefix', 'laya']);
+});
+
+test('hybrid mode safely preserves algorithm output without Laya', () => {
+    assert.equal(fusion.applyLanguageMode(algo, null, 'hybrid'), algo);
+});
+
+test('batch descriptors contain only safe metadata in the backend id/text contract', () => {
+    const descriptor = fusion.buildLayaDescriptor({
+        sourceId: 4,
+        name: '|FR| Sports',
+        groupTitle: 'Sports',
+        sourceName: 'Provider',
+        tvgId: 'sports.fr',
+        url: 'https://user:secret@example.test/live'
+    }, '4:channel-1', algo);
+    assert.deepEqual(Object.keys(descriptor), ['id', 'text']);
+    assert.equal(descriptor.id, '4:channel-1');
+    assert.match(descriptor.text, /sourceId: 4/);
+    assert.doesNotMatch(descriptor.text, /secret|https:\/\//);
+});

test/channelVariantGrouping.test.js

@@ -59,3 +59,19 @@ test('favorites group updates are disabled for flat lists', () => {
     assert.equal(grouping.shouldUseFavoritesGroup('flat'), false);
     assert.equal(grouping.shouldUseFavoritesGroup('grouped'), true);
 });
+
+test('Laya language results participate in variant selection', () => {
+    const lowQualityFrench = channel('1', 'Sports One SD');
+    const highQualityEnglish = channel('2', 'Sports One 4K');
+    const languageResults = new Map([
+        [grouping.getVariantKey(lowQualityFrench), { language: 'fr', confidence: 0.92 }],
+        [grouping.getVariantKey(highQualityEnglish), { language: 'en', confidence: 0.94 }]
+    ]);
+    const logical = grouping.groupChannels([lowQualityFrench, highQualityEnglish], {
+        languageMode: 'laya',
+        languageResults,
+        preferredLanguage: 'fr'
+    })[0];
+    assert.equal(logical.preferredVariant.id, '1');
+    assert.deepEqual(logical.availableLanguages.map(item => item.code), ['fr', 'en']);
+});

test/layaService.test.js

@@ -0,0 +1,44 @@
+const test = require('node:test');
+const assert = require('node:assert/strict');
+const fs = require('fs/promises');
+const os = require('os');
+const path = require('path');
+const {
+    LayaRequestError,
+    LayaService,
+    clearDirectoryContents,
+    validateBatchPayload
+} = require('../server/services/layaService');
+
+test('status reports an unavailable runtime without throwing', async () => {
+    const modelDir = await fs.mkdtemp(path.join(os.tmpdir(), 'nodecast-laya-status-'));
+    const service = new LayaService({
+        modelDir,
+        cache: null,
+        fetch: async () => { throw new Error('connection refused'); }
+    });
+    const status = await service.status();
+    assert.equal(status.runtimeAvailable, false);
+    assert.equal(status.modelPresent, false);
+});
+
+test('model deletion remains limited to the configured model directory', async () => {
+    const parent = await fs.mkdtemp(path.join(os.tmpdir(), 'nodecast-laya-delete-'));
+    const modelDir = path.join(parent, 'models');
+    const sentinel = path.join(parent, 'keep.txt');
+    await fs.mkdir(path.join(modelDir, 'nested'), { recursive: true });
+    await fs.writeFile(path.join(modelDir, 'nested', 'model.bin'), 'model');
+    await fs.writeFile(sentinel, 'keep');
+
+    await clearDirectoryContents(modelDir);
+
+    assert.deepEqual(await fs.readdir(modelDir), []);
+    assert.equal(await fs.readFile(sentinel, 'utf8'), 'keep');
+});
+
+test('batch validation rejects oversized item counts', () => {
+    assert.throws(
+        () => validateBatchPayload({ items: Array.from({ length: 65 }, (_, id) => ({ id, text: 'channel' })) }),
+        error => error instanceof LayaRequestError && error.statusCode === 413
+    );
+});

test/settingsDefaults.test.js

@@ -5,3 +5,7 @@ const { getDefaultSettings } = require('../server/db');
 test('defaults Live TV channel lists to grouped mode', () => {
     assert.equal(getDefaultSettings().liveChannelListMode, 'grouped');
 });
+
+test('defaults language detection to the safe algorithmic mode', () => {
+    assert.equal(getDefaultSettings().languageDetectionMode, 'algo');
+});