diff --git a/src/hooks/frontmatterOps.test.ts b/src/hooks/frontmatterOps.test.ts
new file mode 100644
index 00000000..117cfefa
--- /dev/null
+++ b/src/hooks/frontmatterOps.test.ts
@@ -0,0 +1,25 @@
+import { describe, it, expect } from 'vitest'
+import { frontmatterToEntryPatch } from './frontmatterOps'
+
+describe('frontmatterToEntryPatch — _pinned_properties', () => {
+  it('patches pinnedProperties on update', () => {
+    const result = frontmatterToEntryPatch('update', '_pinned_properties', ['Status:circle-dot', 'Date'])
+    expect(result.patch.pinnedProperties).toEqual([
+      { key: 'Status', icon: 'circle-dot' },
+      { key: 'Date', icon: null },
+    ])
+    expect(result.relationshipPatch).toBeNull()
+  })
+
+  it('clears pinnedProperties on delete', () => {
+    const result = frontmatterToEntryPatch('delete', '_pinned_properties')
+    expect(result.patch.pinnedProperties).toEqual([])
+    expect(result.relationshipPatch).toBeNull()
+  })
+
+  it('ignores non-array _pinned_properties values', () => {
+    const result = frontmatterToEntryPatch('update', '_pinned_properties', 'not-an-array')
+    // Falls through to default handling (no patch for unknown keys)
+    expect(result.patch.pinnedProperties).toBeUndefined()
+  })
+})
diff --git a/src/hooks/usePinnedProperties.test.ts b/src/hooks/usePinnedProperties.test.ts
new file mode 100644
index 00000000..a9a36fe3
--- /dev/null
+++ b/src/hooks/usePinnedProperties.test.ts
@@ -0,0 +1,78 @@
+import { describe, it, expect } from 'vitest'
+import {
+  resolvePinIcon,
+  serialisePinnedConfig,
+  parsePinnedConfig,
+} from './usePinnedProperties'
+import type { PinnedPropertyConfig } from '../types'
+
+describe('resolvePinIcon', () => {
+  it('returns explicit icon when provided', () => {
+    expect(resolvePinIcon('status', 'star')).toBe('star')
+  })
+
+  it('returns default icon for known keys', () => {
+    expect(resolvePinIcon('status', null)).toBe('circle-dot')
+    expect(resolvePinIcon('Status', null)).toBe('circle-dot')
+    expect(resolvePinIcon('date', null)).toBe('calendar')
+    expect(resolvePinIcon('Belongs to', null)).toBe('arrow-up-right')
+    expect(resolvePinIcon('Related to', null)).toBe('arrows-left-right')
+    expect(resolvePinIcon('Due date', null)).toBe('calendar')
+  })
+
+  it('returns fallback icon for unknown keys', () => {
+    expect(resolvePinIcon('Priority', null)).toBe('arrow-up-right')
+  })
+})
+
+describe('serialisePinnedConfig', () => {
+  it('serialises configs with icons', () => {
+    const configs: PinnedPropertyConfig[] = [
+      { key: 'Status', icon: 'circle-dot' },
+      { key: 'date', icon: 'calendar' },
+    ]
+    expect(serialisePinnedConfig(configs)).toEqual(['Status:circle-dot', 'date:calendar'])
+  })
+
+  it('serialises configs without icons', () => {
+    const configs: PinnedPropertyConfig[] = [
+      { key: 'Status', icon: null },
+    ]
+    expect(serialisePinnedConfig(configs)).toEqual(['Status'])
+  })
+
+  it('handles empty array', () => {
+    expect(serialisePinnedConfig([])).toEqual([])
+  })
+})
+
+describe('parsePinnedConfig', () => {
+  it('parses key:icon format', () => {
+    expect(parsePinnedConfig(['Status:circle-dot'])).toEqual([
+      { key: 'Status', icon: 'circle-dot' },
+    ])
+  })
+
+  it('parses key-only format', () => {
+    expect(parsePinnedConfig(['Status'])).toEqual([
+      { key: 'Status', icon: null },
+    ])
+  })
+
+  it('handles mixed formats', () => {
+    const result = parsePinnedConfig(['Status:circle-dot', 'Priority', 'date:calendar'])
+    expect(result).toEqual([
+      { key: 'Status', icon: 'circle-dot' },
+      { key: 'Priority', icon: null },
+      { key: 'date', icon: 'calendar' },
+    ])
+  })
+
+  it('round-trips with serialise', () => {
+    const configs: PinnedPropertyConfig[] = [
+      { key: 'Status', icon: 'circle-dot' },
+      { key: 'Belongs to', icon: 'arrow-up-right' },
+    ]
+    expect(parsePinnedConfig(serialisePinnedConfig(configs))).toEqual(configs)
+  })
+})