diff --git a/packages/mumo/src/App.svelte b/packages/mumo/src/App.svelte
index 1db13ce..547bffd 100644
--- a/packages/mumo/src/App.svelte
+++ b/packages/mumo/src/App.svelte
@@ -4322,7 +4322,9 @@ let patternSchemaDlgOpen = $state(false)
   async function applyTemplate() {
     const file = await platform.openBinaryFile(['mmetf', 'etf'], 'Template files')
     if (!file) return
-    const text = await file.file.text()
+    const text = file.path && isDesktop(platform)
+      ? new TextDecoder().decode(await platform.readFileAsBytes(file.path))
+      : await file.file.text()
     const ext = (file.path ?? file.file.name).split('.').pop()?.toLowerCase()
     let tmpl: Parameters<typeof buildTemplateMerge>[0]
     try {
diff --git a/packages/serialization/tests/template-apply.test.ts b/packages/serialization/tests/template-apply.test.ts
new file mode 100644
index 0000000..ecdd074
--- /dev/null
+++ b/packages/serialization/tests/template-apply.test.ts
@@ -0,0 +1,61 @@
+import { describe, it, expect } from 'vitest'
+import { parseMMETF, parseMMEAF, emitMMEAF, emitMMETF } from '../src/index.js'
+import { AnnotationStore } from '@mumo/core'
+import { buildTemplateMerge } from '../../mumo/src/template-merge.js'
+
+function makeStore() { return new AnnotationStore() }
+
+describe('template apply end-to-end', () => {
+  it('applies vocab, LT, and pattern schema from template onto a transcript-loaded store', () => {
+    // Build a transcript store with some LTs and a pattern schema (simulates transcript.mmeaf)
+    const transcriptStore = makeStore()
+    transcriptStore.addLinguisticType('default-lt')
+    transcriptStore.addLinguisticType('symbolic_association', { constraint: 'symbolic_association' })
+    const repairSchema = transcriptStore.addPatternSchema({ name: 'repair', slots: [] })
+
+    // Round-trip through MMEAF serialization (same path as the app's MMEAF importer)
+    const emptyDoc = { type: 'doc', content: [] } as never
+    const transcriptXml = emitMMEAF(emptyDoc, transcriptStore)
+    const transcriptResult = parseMMEAF(transcriptXml)
+    const store = makeStore()
+    store.loadJSON({
+      annotations: transcriptResult.annotations,
+      tiers: transcriptResult.tiers,
+      vocabularies: transcriptResult.vocabularies,
+      linguisticTypes: transcriptResult.linguisticTypes,
+      patternSchemas: transcriptResult.patternSchemas,
+      patterns: transcriptResult.patterns,
+      participants: transcriptResult.participants,
+    })
+
+    expect(store.allPatternSchemas().map(s => s.name)).toContain('repair')
+
+    // Build a template store with vocab "test", LT "blah" (referencing vocab), pattern schema "howdy"
+    const templateStore = makeStore()
+    const vocab = templateStore.addVocabulary('test', [
+      { id: 'e1', value: 'A', description: 'B' },
+      { id: 'e2', value: 'C', description: 'D' },
+    ])
+    templateStore.addLinguisticType('blah', { constraint: 'symbolic_association', vocabularyId: vocab.id })
+    templateStore.addPatternSchema({
+      name: 'howdy',
+      slots: [{ id: 's1', name: 'a', anchorKind: 'any', required: true, metrics: [] }],
+    })
+
+    // Round-trip through MMETF serialization (same path as Save Template → Apply Template)
+    const templateXml = emitMMETF(templateStore)
+    const tmpl = parseMMETF(templateXml)
+
+    // Apply
+    const merge = buildTemplateMerge(tmpl, store)
+    expect(merge.conflicts).toHaveLength(0)
+    expect(merge.preview.some(s => s.items.some(i => i.action !== 'skip'))).toBe(true)
+
+    merge.applyFn(store)
+
+    expect(store.allVocabularies().map(v => v.name)).toContain('test')
+    expect(store.allLinguisticTypes().map(lt => lt.name)).toContain('blah')
+    expect(store.allPatternSchemas().map(s => s.name)).toContain('howdy')
+    expect(store.allPatternSchemas().map(s => s.name)).toContain('repair')
+  })
+})