diff --git a/src/world/roundtrip.test.ts b/src/world/roundtrip.test.ts
new file mode 100644
index 0000000..6d9368f
--- /dev/null
+++ b/src/world/roundtrip.test.ts
@@ -0,0 +1,71 @@
+import { describe, it, expect } from 'vitest'
+import { parseRoom, parseItem, parseEnding, parseEncounterNarration } from './loader'
+import { rooms } from './rooms'
+import { items } from './items'
+import { encounters } from './encounters'
+import { endings } from './story'
+
+const roomFiles = import.meta.glob<string>('./rooms/*.md', {
+  eager: true, query: '?raw', import: 'default',
+})
+const itemFiles = import.meta.glob<string>('./items/*.md', {
+  eager: true, query: '?raw', import: 'default',
+})
+const endingFiles = import.meta.glob<string>('./endings/*.md', {
+  eager: true, query: '?raw', import: 'default',
+})
+const encounterFiles = import.meta.glob<string>('./encounters/*.md', {
+  eager: true, query: '?raw', import: 'default',
+})
+
+describe('round-trip: rooms', () => {
+  it('parses each room file back to the original Room', () => {
+    for (const [path, raw] of Object.entries(roomFiles)) {
+      const parsed = parseRoom(raw, path)
+      const original = rooms[parsed.id]
+      expect(original, `room ${parsed.id} missing in source TS`).toBeDefined()
+      expect(parsed).toEqual(original)
+    }
+  })
+})
+
+describe('round-trip: items', () => {
+  it('parses each item file back to the original Item', () => {
+    for (const [path, raw] of Object.entries(itemFiles)) {
+      const parsed = parseItem(raw, path)
+      const original = items[parsed.id]
+      expect(original, `item ${parsed.id} missing in source TS`).toBeDefined()
+      expect(parsed).toEqual(original)
+    }
+  })
+})
+
+describe('round-trip: endings', () => {
+  it('parses each ending file back to the original ending', () => {
+    for (const [path, raw] of Object.entries(endingFiles)) {
+      const { id, ending } = parseEnding(raw, path)
+      const original = endings[id]
+      expect(ending.whenFlags).toEqual(original.whenFlags)
+      expect(ending.narration).toEqual(original.narration)
+    }
+  })
+})
+
+describe('round-trip: encounters narration', () => {
+  it('captures every inline narration string', () => {
+    for (const [path, raw] of Object.entries(encounterFiles)) {
+      const doc = parseEncounterNarration(raw, path)
+      const original = encounters[doc.id]
+      expect(original).toBeDefined()
+      for (const [phaseName, phase] of Object.entries(original.phases)) {
+        expect(doc.narrations[phaseName], `phase ${phaseName} narration missing`).toBe(phase.description)
+      }
+      const allNarrations = new Set(Object.values(doc.narrations))
+      for (const phase of Object.values(original.phases)) {
+        for (const t of phase.transitions) {
+          expect(allNarrations.has(t.narration), `transition narration missing: "${t.narration}"`).toBe(true)
+        }
+      }
+    }
+  })
+})