diff --git a/apps/mobile/src/demoData.ts b/apps/mobile/src/demoData.ts
index 31270846..50ba2ef8 100644
--- a/apps/mobile/src/demoData.ts
+++ b/apps/mobile/src/demoData.ts
@@ -1,4 +1,5 @@
 import { projectMobileNotes, type MobileNote, type MobileNoteSource } from './mobileNoteProjection'
+import { createFixtureMobileVaultRepository } from './mobileVaultRepository'
 
 export type { MobileNote } from './mobileNoteProjection'
 
@@ -67,6 +68,8 @@ const noteContent: MobileNoteSource[] = [
 
 export const notes: MobileNote[] = projectMobileNotes(noteContent)
 
+export const demoVaultRepository = createFixtureMobileVaultRepository(noteContent)
+
 export const sidebarSections = [
   {
     title: 'Library',
diff --git a/apps/mobile/src/mobileVaultRepository.test.ts b/apps/mobile/src/mobileVaultRepository.test.ts
new file mode 100644
index 00000000..ce67dc90
--- /dev/null
+++ b/apps/mobile/src/mobileVaultRepository.test.ts
@@ -0,0 +1,46 @@
+import { describe, expect, it } from 'vitest'
+import { createFixtureMobileVaultRepository } from './mobileVaultRepository'
+import type { MobileNoteSource } from './mobileNoteProjection'
+
+const sources: MobileNoteSource[] = [
+  createSource('workflow', 'Workflow Orchestration Essay'),
+  createSource('release', 'v2026-05-02'),
+]
+
+describe('mobile vault repository', () => {
+  it('lists projected notes in vault order', async () => {
+    const repository = createFixtureMobileVaultRepository(sources)
+    const notes = await repository.listNotes()
+
+    expect(notes.map((note) => note.id)).toEqual(['workflow', 'release'])
+    expect(notes[0].title).toBe('Workflow Orchestration Essay')
+  })
+
+  it('reads a projected note by id', async () => {
+    const repository = createFixtureMobileVaultRepository(sources)
+
+    await expect(repository.readNote('release')).resolves.toMatchObject({
+      id: 'release',
+      title: 'v2026-05-02',
+    })
+  })
+
+  it('returns null for missing notes', async () => {
+    const repository = createFixtureMobileVaultRepository(sources)
+
+    await expect(repository.readNote('missing')).resolves.toBeNull()
+  })
+})
+
+function createSource(id: string, title: string): MobileNoteSource {
+  return {
+    id,
+    type: 'Essay',
+    icon: 'pen-nib',
+    date: 'May 13, 2026',
+    modified: '6h ago',
+    filename: `${id}.md`,
+    tags: ['Tolaria MVP'],
+    content: `---\ntitle: ${title}\n---\n\n# ${title}\n\nBody text for ${title}.`,
+  }
+}
diff --git a/apps/mobile/src/mobileVaultRepository.ts b/apps/mobile/src/mobileVaultRepository.ts
new file mode 100644
index 00000000..18fb394c
--- /dev/null
+++ b/apps/mobile/src/mobileVaultRepository.ts
@@ -0,0 +1,15 @@
+import { projectMobileNotes, type MobileNote, type MobileNoteSource } from './mobileNoteProjection'
+
+export type MobileVaultRepository = {
+  listNotes: () => Promise<MobileNote[]>
+  readNote: (id: string) => Promise<MobileNote | null>
+}
+
+export function createFixtureMobileVaultRepository(sources: MobileNoteSource[]): MobileVaultRepository {
+  const notes = projectMobileNotes(sources)
+
+  return {
+    listNotes: () => Promise.resolve(notes),
+    readNote: (id) => Promise.resolve(notes.find((note) => note.id === id) ?? null),
+  }
+}
diff --git a/docs/MOBILE_PROGRESS.md b/docs/MOBILE_PROGRESS.md
index 71d74c4d..f8a3bfff 100644
--- a/docs/MOBILE_PROGRESS.md
+++ b/docs/MOBILE_PROGRESS.md
@@ -8,7 +8,7 @@ This file is the resumable working log for Tolaria mobile. The strategy and road
 
 - Branch: `codex/mobile`
 - Active phase: Phase 2 - Mobile Shell
-- Active slice: Separate mobile note projection from fixtures
+- Active slice: Define mobile vault repository boundary
 - Push policy: commit locally; do not push unless explicitly requested
 - Validation target: iPad/iOS simulator first
 
@@ -36,6 +36,7 @@ This file is the resumable working log for Tolaria mobile. The strategy and road
 - Pinned Expo runtime dependencies to the versions expected by Expo 55 after the initial generated versions failed iOS bundle export (`react-native@0.83.6`, `react@19.2.0`, matching safe-area/svg versions).
 - Extracted compact phone navigation into a pure tested state machine so future swipe gestures can dispatch explicit events instead of mutating panels ad hoc.
 - Extracted mobile note projection into a pure module that turns raw vault-like note records into the list/editor shape used by the mobile shell.
+- Added a minimal mobile vault repository contract plus fixture implementation so app-local vault storage and git sync can plug in behind `listNotes` / `readNote` later.
 
 ## Next Action
 
@@ -90,6 +91,10 @@ Continue Phase 2 with the next mobile shell slice:
 - `pnpm --filter @tolaria/mobile typecheck` passed after note projection extraction.
 - CodeScene after note projection extraction: `apps/mobile/src/mobileNoteProjection.ts` and `apps/mobile/src/mobileNoteProjection.test.ts` scored `10`; `apps/mobile/src/demoData.ts` returned no scorable code and no findings.
 - `pnpm --filter @tolaria/mobile exec expo export --platform ios --output-dir /tmp/tolaria-mobile-export` passed after note projection extraction.
+- `pnpm --filter @tolaria/mobile test` passed after mobile vault repository extraction: 4 files / 11 tests.
+- `pnpm --filter @tolaria/mobile typecheck` passed after mobile vault repository extraction.
+- CodeScene after mobile vault repository extraction: `apps/mobile/src/mobileVaultRepository.ts` and `apps/mobile/src/mobileVaultRepository.test.ts` scored `10`; `apps/mobile/src/demoData.ts` still returned no scorable code and no findings.
+- `pnpm --filter @tolaria/mobile exec expo export --platform ios --output-dir /tmp/tolaria-mobile-export` passed after mobile vault repository extraction.
 
 ## Risks / Watch Items