diff --git a/apps/api/src/lib/rank.test.ts b/apps/api/src/lib/rank.test.ts
new file mode 100644
index 0000000..721f0db
--- /dev/null
+++ b/apps/api/src/lib/rank.test.ts
@@ -0,0 +1,78 @@
+/**
+ * Unit tests for rank.ts — fractional-indexing helpers (D-13).
+ *
+ * Pure function tests, no DB needed.
+ * Run: pnpm --filter @familysync/api exec vitest run src/lib/rank.test.ts
+ */
+
+import { describe, it, expect } from 'vitest'
+import { rankForAppend, rankBetween } from './rank.js'
+
+describe('rankForAppend', () => {
+  it('returns "a0" when list is empty (no existing rank)', () => {
+    const rank = rankForAppend(null)
+    expect(rank).toBe('a0')
+  })
+
+  it('returns a rank string that sorts AFTER the given last rank', () => {
+    const lastRank = 'a0'
+    const newRank = rankForAppend(lastRank)
+    expect(newRank > lastRank).toBe(true)
+  })
+
+  it('multiple appends produce strictly increasing ranks', () => {
+    let last: string | null = null
+    const ranks: string[] = []
+    for (let i = 0; i < 5; i++) {
+      const r = rankForAppend(last)
+      ranks.push(r)
+      last = r
+    }
+    // Each successive rank must be greater than the previous
+    for (let i = 1; i < ranks.length; i++) {
+      expect(ranks[i] > ranks[i - 1]).toBe(true)
+    }
+  })
+})
+
+describe('rankBetween', () => {
+  it('returns "a0" when both prev and next are null (empty list)', () => {
+    const rank = rankBetween(null, null)
+    expect(rank).toBe('a0')
+  })
+
+  it('returns a rank that sorts between two existing ranks', () => {
+    const first = rankForAppend(null)    // 'a0'
+    const second = rankForAppend(first)  // 'a1'
+    const between = rankBetween(first, second)
+    expect(between > first).toBe(true)
+    expect(between < second).toBe(true)
+  })
+
+  it('returns a rank that sorts AFTER prev when next is null', () => {
+    const prev = 'a0'
+    const rank = rankBetween(prev, null)
+    expect(rank > prev).toBe(true)
+  })
+
+  it('returns a rank that sorts BEFORE next when prev is null', () => {
+    const next = 'a1'
+    const rank = rankBetween(null, next)
+    expect(rank < next).toBe(true)
+  })
+
+  it('produces lexicographically stable ordering across multiple insertions', () => {
+    // Simulate inserting between 'a0' and 'a1' repeatedly
+    const a = 'a0'
+    const b = 'a1'
+    const c = rankBetween(a, b)
+    const d = rankBetween(a, c)
+    const e = rankBetween(c, b)
+
+    // All four ranks should be orderable
+    expect(a < d).toBe(true)
+    expect(d < c).toBe(true)
+    expect(c < e).toBe(true)
+    expect(e < b).toBe(true)
+  })
+})
diff --git a/apps/api/tests/routes/lists.test.ts b/apps/api/tests/routes/lists.test.ts
index 59d3741..9944c9f 100644
--- a/apps/api/tests/routes/lists.test.ts
+++ b/apps/api/tests/routes/lists.test.ts
@@ -19,7 +19,7 @@
 import { describe, it, expect, beforeEach, vi } from 'vitest'
 import { randomUUID } from 'node:crypto'
 import { db } from '../../src/db/client.js'
-import { users, lists, listShares } from '../../src/db/schema.js'
+import { users, lists, listShares, listItems } from '../../src/db/schema.js'
 
 // ---------------------------------------------------------------------------
 // Dev-bypass mock: inject a specific user ID as the "logged-in" user.
@@ -449,3 +449,279 @@ describe('PATCH /api/lists/:id (authorized update)', () => {
     expect(body.name).toBe('Sharee Renamed')
   })
 })
+
+// ---------------------------------------------------------------------------
+// Item route tests (LIST-02) — D-05/D-06/D-08/D-09/D-13
+// ---------------------------------------------------------------------------
+
+async function seedItem(
+  listId: number,
+  text: string,
+  rank: string,
+  checked = false,
+): Promise<number> {
+  const { eq } = await import('drizzle-orm')
+  const [result] = await db.insert(listItems).values({ listId, text, rank, checked }).$returningId()
+  return result.id
+}
+
+// ---------------------------------------------------------------------------
+// POST /api/lists/:id/items — add item (LIST-02, D-13)
+// ---------------------------------------------------------------------------
+
+describe('POST /api/lists/:id/items — add item (LIST-02, D-13)', () => {
+  it('inserts an item and returns id/listId/text/checked/rank', async () => {
+    const ownerId = await seedUser('post-item-owner')
+    currentDevUserId = ownerId
+    const listId = await seedList(ownerId, 'Item List', false)
+
+    const app = await getApp()
+    const res = await app.request(jsonRequest('POST', `/api/lists/${listId}/items`, { text: 'milk' }))
+    expect(res.status).toBe(201)
+    const body = await res.json() as { id: number; listId: number; text: string; checked: boolean; rank: string }
+    expect(body.id).toBeDefined()
+    expect(body.listId).toBe(listId)
+    expect(body.text).toBe('milk')
+    expect(body.checked).toBe(false)
+    expect(body.rank).toBe('a0') // first item → generateKeyBetween(null, null) = 'a0'
+  })
+
+  it('first item in empty list gets rank "a0" (generateKeyBetween(null, null))', async () => {
+    const ownerId = await seedUser('post-item-first-rank')
+    currentDevUserId = ownerId
+    const listId = await seedList(ownerId, 'Rank List', false)
+
+    const app = await getApp()
+    const res = await app.request(jsonRequest('POST', `/api/lists/${listId}/items`, { text: 'first' }))
+    expect(res.status).toBe(201)
+    const body = await res.json() as { rank: string }
+    expect(body.rank).toBe('a0')
+  })
+
+  it('second item rank sorts after first item rank (append to active bottom)', async () => {
+    const ownerId = await seedUser('post-item-second-rank')
+    currentDevUserId = ownerId
+    const listId = await seedList(ownerId, 'Rank Append List', false)
+    await seedItem(listId, 'first', 'a0')
+
+    const app = await getApp()
+    const res = await app.request(jsonRequest('POST', `/api/lists/${listId}/items`, { text: 'second' }))
+    expect(res.status).toBe(201)
+    const body = await res.json() as { rank: string }
+    expect(body.rank > 'a0').toBe(true)
+  })
+
+  it('rejects an empty text with 400 (zod validation)', async () => {
+    const ownerId = await seedUser('post-item-empty-text')
+    currentDevUserId = ownerId
+    const listId = await seedList(ownerId, 'Zod Item List', false)
+
+    const app = await getApp()
+    const res = await app.request(jsonRequest('POST', `/api/lists/${listId}/items`, { text: '' }))
+    expect(res.status).toBe(400)
+  })
+
+  it('returns 403 when caller has no list access', async () => {
+    const ownerId = await seedUser('post-item-403-owner')
+    const otherId = await seedUser('post-item-403-other')
+    const listId = await seedList(ownerId, 'Private List Items', false)
+
+    currentDevUserId = otherId
+    const app = await getApp()
+    const res = await app.request(jsonRequest('POST', `/api/lists/${listId}/items`, { text: 'sneaky' }))
+    expect(res.status).toBe(403)
+  })
+})
+
+// ---------------------------------------------------------------------------
+// GET /api/lists/:id/items — access-gated item fetch (LIST-02)
+// ---------------------------------------------------------------------------
+
+describe('GET /api/lists/:id/items — access-gated fetch (LIST-02)', () => {
+  it('returns items ordered by rank ASC for list owner', async () => {
+    const ownerId = await seedUser('get-items-owner')
+    currentDevUserId = ownerId
+    const listId = await seedList(ownerId, 'Get Items', false)
+    await seedItem(listId, 'first', 'a0')
+    await seedItem(listId, 'second', 'a1')
+
+    const app = await getApp()
+    const res = await app.request(`/api/lists/${listId}/items`)
+    expect(res.status).toBe(200)
+    const body = await res.json() as { items: Array<{ id: number; text: string; checked: boolean; rank: string }> }
+    expect(body.items.length).toBe(2)
+    expect(body.items[0].text).toBe('first')
+    expect(body.items[1].text).toBe('second')
+    // Shape check
+    expect(body.items[0]).toHaveProperty('id')
+    expect(body.items[0]).toHaveProperty('listId')
+    expect(body.items[0]).toHaveProperty('checked')
+    expect(body.items[0]).toHaveProperty('rank')
+  })
+
+  it('returns 403 for non-member (T-04-05)', async () => {
+    const ownerId = await seedUser('get-items-403-owner')
+    const otherId = await seedUser('get-items-403-other')
+    const listId = await seedList(ownerId, 'Private Items', false)
+
+    currentDevUserId = otherId
+    const app = await getApp()
+    const res = await app.request(`/api/lists/${listId}/items`)
+    expect(res.status).toBe(403)
+  })
+})
+
+// ---------------------------------------------------------------------------
+// PATCH /api/list-items/:id — per-field LWW update (D-08)
+// ---------------------------------------------------------------------------
+
+describe('PATCH /api/list-items/:id — per-field LWW (D-08)', () => {
+  it('PATCH { checked: true } updates only checked field', async () => {
+    const ownerId = await seedUser('patch-item-check')
+    currentDevUserId = ownerId
+    const listId = await seedList(ownerId, 'Patch Check', false)
+    const itemId = await seedItem(listId, 'bread', 'a0')
+
+    const app = await getApp()
+    const res = await app.request(jsonRequest('PATCH', `/api/list-items/${itemId}`, { checked: true }))
+    expect(res.status).toBe(200)
+    const body = await res.json() as { checked: boolean; text: string }
+    expect(body.checked).toBe(true)
+    expect(body.text).toBe('bread') // text unchanged
+  })
+
+  it('PATCH { checked: false } (uncheck) moves item to active bottom — rank after last active', async () => {
+    const ownerId = await seedUser('patch-item-uncheck')
+    currentDevUserId = ownerId
+    const listId = await seedList(ownerId, 'Uncheck Rank', false)
+    // Two active items
+    await seedItem(listId, 'alpha', 'a0')
+    const lastActiveId = await seedItem(listId, 'beta', 'a1')
+    // One checked item (to uncheck)
+    const checkedItemId = await seedItem(listId, 'checked-one', 'Zz', true)
+
+    const app = await getApp()
+    const res = await app.request(jsonRequest('PATCH', `/api/list-items/${checkedItemId}`, { checked: false }))
+    expect(res.status).toBe(200)
+    const body = await res.json() as { checked: boolean; rank: string }
+    expect(body.checked).toBe(false)
+    // rank must sort AFTER the last active item's rank ('a1')
+    expect(body.rank > 'a1').toBe(true)
+  })
+
+  it('PATCH { text: "eggs" } updates only text field (LWW D-08)', async () => {
+    const ownerId = await seedUser('patch-item-text')
+    currentDevUserId = ownerId
+    const listId = await seedList(ownerId, 'Patch Text', false)
+    const itemId = await seedItem(listId, 'old text', 'a0')
+
+    const app = await getApp()
+    const res = await app.request(jsonRequest('PATCH', `/api/list-items/${itemId}`, { text: 'new text' }))
+    expect(res.status).toBe(200)
+    const body = await res.json() as { text: string; checked: boolean }
+    expect(body.text).toBe('new text')
+    expect(body.checked).toBe(false) // checked unchanged
+  })
+
+  it('PATCH with two fields is rejected by zod refine (exactly-one-field D-08, T-04-07)', async () => {
+    const ownerId = await seedUser('patch-item-two-fields')
+    currentDevUserId = ownerId
+    const listId = await seedList(ownerId, 'Two Fields', false)
+    const itemId = await seedItem(listId, 'item', 'a0')
+
+    const app = await getApp()
+    const res = await app.request(jsonRequest('PATCH', `/api/list-items/${itemId}`, { checked: true, text: 'nope' }))
+    // @hono/zod-validator returns 400 on schema violations (matches events.ts convention)
+    expect(res.status).toBe(400)
+  })
+
+  it('PATCH with empty body is rejected (no fields)', async () => {
+    const ownerId = await seedUser('patch-item-empty-body')
+    currentDevUserId = ownerId
+    const listId = await seedList(ownerId, 'Empty Body', false)
+    const itemId = await seedItem(listId, 'item', 'a0')
+
+    const app = await getApp()
+    const res = await app.request(jsonRequest('PATCH', `/api/list-items/${itemId}`, {}))
+    expect(res.status).toBe(400)
+  })
+
+  it('returns 403 when caller has no list access (T-04-05)', async () => {
+    const ownerId = await seedUser('patch-item-403-owner')
+    const otherId = await seedUser('patch-item-403-other')
+    const listId = await seedList(ownerId, 'Private Items Patch', false)
+    const itemId = await seedItem(listId, 'secret', 'a0')
+
+    currentDevUserId = otherId
+    const app = await getApp()
+    const res = await app.request(jsonRequest('PATCH', `/api/list-items/${itemId}`, { checked: true }))
+    expect(res.status).toBe(403)
+  })
+})
+
+// ---------------------------------------------------------------------------
+// DELETE /api/list-items/:id — delete-wins (D-06/D-09)
+// ---------------------------------------------------------------------------
+
+describe('DELETE /api/list-items/:id — delete-wins (D-06/D-09)', () => {
+  it('owner can delete an item', async () => {
+    const ownerId = await seedUser('del-item-owner')
+    currentDevUserId = ownerId
+    const listId = await seedList(ownerId, 'Delete Item', false)
+    const itemId = await seedItem(listId, 'doomed item', 'a0')
+
+    const app = await getApp()
+    const res = await app.request(new Request(`http://localhost/api/list-items/${itemId}`, { method: 'DELETE' }))
+    expect(res.status).toBe(200)
+
+    // Verify gone from DB
+    const { eq } = await import('drizzle-orm')
+    const remaining = await db.select().from(listItems).where(eq(listItems.id, itemId))
+    expect(remaining.length).toBe(0)
+  })
+
+  it('sharee can delete an item in a shared list', async () => {
+    const ownerId = await seedUser('del-item-sharee-owner')
+    const shareeId = await seedUser('del-item-sharee-sharee')
+    const listId = await seedList(ownerId, 'Shared Del List', true)
+    await shareList(listId, shareeId)
+    const itemId = await seedItem(listId, 'sharee deletes', 'a0')
+
+    currentDevUserId = shareeId
+    const app = await getApp()
+    const res = await app.request(new Request(`http://localhost/api/list-items/${itemId}`, { method: 'DELETE' }))
+    expect(res.status).toBe(200)
+  })
+
+  it('returns 403 when caller has no list access (T-04-05)', async () => {
+    const ownerId = await seedUser('del-item-403-owner')
+    const otherId = await seedUser('del-item-403-other')
+    const listId = await seedList(ownerId, 'Private Del List', false)
+    const itemId = await seedItem(listId, 'can t delete', 'a0')
+
+    currentDevUserId = otherId
+    const app = await getApp()
+    const res = await app.request(new Request(`http://localhost/api/list-items/${itemId}`, { method: 'DELETE' }))
+    expect(res.status).toBe(403)
+
+    // Verify item still exists (delete-wins semantics: only succeeds if authorized)
+    const { eq } = await import('drizzle-orm')
+    const remaining = await db.select().from(listItems).where(eq(listItems.id, itemId))
+    expect(remaining.length).toBe(1)
+  })
+
+  it('delete-wins: PATCH on deleted item affects zero rows (no resurrection D-09)', async () => {
+    const ownerId = await seedUser('del-wins-owner')
+    currentDevUserId = ownerId
+    const listId = await seedList(ownerId, 'Del Wins', false)
+    const itemId = await seedItem(listId, 'ephemeral', 'a0')
+
+    // Delete first
+    const app = await getApp()
+    await app.request(new Request(`http://localhost/api/list-items/${itemId}`, { method: 'DELETE' }))
+
+    // PATCH after delete should 404 (no row to update)
+    const patchRes = await app.request(jsonRequest('PATCH', `/api/list-items/${itemId}`, { checked: true }))
+    expect(patchRes.status).toBe(404)
+  })
+})