diff --git a/apps/backend/src/repositories/inventory-repo.js b/apps/backend/src/repositories/inventory-repo.ts
similarity index 79%
rename from apps/backend/src/repositories/inventory-repo.js
rename to apps/backend/src/repositories/inventory-repo.ts
index 6e00781f..8bd30167 100644
--- a/apps/backend/src/repositories/inventory-repo.js
+++ b/apps/backend/src/repositories/inventory-repo.ts
@@ -1,13 +1,21 @@
-// @ts-check
-
 import { query, withTransaction } from '../db/client.js'
+import type {
+  InventoryCreateItemInput,
+  InventoryListQueryInput,
+  InventorySkuSuggestionQueryInput,
+} from '../types/repository-inputs.js'
+import type {
+  InventoryItemRow,
+  InventoryListQueryResult,
+  InventorySkuSuggestionRow,
+} from '../types/repository-rows.js'
 
-/** @typedef {import('../types/repository-inputs.js').InventoryCreateItemInput} InventoryCreateItemInput */
-/** @typedef {import('../types/repository-inputs.js').InventoryListQueryInput} InventoryListQueryInput */
-/** @typedef {import('../types/repository-inputs.js').InventorySkuSuggestionQueryInput} InventorySkuSuggestionQueryInput */
-/** @typedef {import('../types/repository-rows.js').InventoryItemRow} InventoryItemRow */
-/** @typedef {import('../types/repository-rows.js').InventoryListQueryResult} InventoryListQueryResult */
-/** @typedef {import('../types/repository-rows.js').InventorySkuSuggestionRow} InventorySkuSuggestionRow */
+type InventoryGroupCodesInput = string | string[] | null | undefined
+
+type InventoryGroupListInput = {
+  keyword?: string
+  limit?: number | string
+}
 
 const INVENTORY_ITEM_SELECT = `
   SELECT
@@ -36,18 +44,17 @@ const INVENTORY_ITEM_SELECT = `
   LEFT JOIN fulfillment_tasks ft ON ft.id = tib.task_id
 `
 
-/** @returns {Promise<InventoryItemRow | null>} */
 export async function findFirstAvailableInventoryItemBySkuCode(
-  skuCode,
+  skuCode: string,
   credentialType = 'tencent_code',
-  inventoryGroupCodes = null,
-) {
+  inventoryGroupCodes: InventoryGroupCodesInput = null,
+): Promise<InventoryItemRow | null> {
   const normalizedInventoryGroupCodes = normalizeInventoryGroupCodes(inventoryGroupCodes)
   if (normalizedInventoryGroupCodes && normalizedInventoryGroupCodes.length === 0) {
     return null
   }
 
-  const params = [skuCode, credentialType]
+  const params: unknown[] = [skuCode, credentialType]
   const filters = [
     'ii.sku_code = $1',
     'ii.credential_type = $2',
@@ -59,7 +66,7 @@ export async function findFirstAvailableInventoryItemBySkuCode(
     filters.push(`ii.inventory_group_code = ANY($${params.length}::text[])`)
   }
 
-  const result = await query(
+  const result = await query<InventoryItemRow>(
     `${INVENTORY_ITEM_SELECT}
      WHERE ${filters.join(' AND ')}
      ORDER BY ii.id ASC
@@ -67,11 +74,15 @@ export async function findFirstAvailableInventoryItemBySkuCode(
     params,
   )
 
-  return /** @type {InventoryItemRow | null} */ (result.rows[0] || null)
+  return result.rows[0] || null
 }
 
-/** @returns {Promise<InventoryItemRow | null>} */
-export async function assignReservedInventoryItem(inventoryItemId, taskId, updatedAt, roleKey = 'primary_code') {
+export async function assignReservedInventoryItem(
+  inventoryItemId: number | string,
+  taskId: number | string,
+  updatedAt: string,
+  roleKey = 'primary_code',
+): Promise<InventoryItemRow | null> {
   return withTransaction(async (client) => {
     const inventoryResult = await client.query(
       `
@@ -109,20 +120,21 @@ export async function assignReservedInventoryItem(inventoryItemId, taskId, updat
   })
 }
 
-/** @returns {Promise<InventoryItemRow | null>} */
-export async function getInventoryItemById(inventoryItemId) {
-  const result = await query(
+export async function getInventoryItemById(inventoryItemId: number | string): Promise<InventoryItemRow | null> {
+  const result = await query<InventoryItemRow>(
     `${INVENTORY_ITEM_SELECT}
      WHERE ii.id = $1
      LIMIT 1`,
     [Number(inventoryItemId)],
   )
 
-  return /** @type {InventoryItemRow | null} */ (result.rows[0] || null)
+  return result.rows[0] || null
 }
 
-/** @returns {Promise<InventoryItemRow | null>} */
-export async function markInventoryItemDelivered(inventoryItemId, deliveredAt) {
+export async function markInventoryItemDelivered(
+  inventoryItemId: number | string,
+  deliveredAt: string,
+): Promise<InventoryItemRow | null> {
   return withTransaction(async (client) => {
     await client.query(
       `
@@ -146,8 +158,11 @@ export async function markInventoryItemDelivered(inventoryItemId, deliveredAt) {
   })
 }
 
-/** @returns {Promise<InventoryItemRow | null>} */
-export async function markInventoryItemConsumed(inventoryItemId, reason, consumedAt) {
+export async function markInventoryItemConsumed(
+  inventoryItemId: number | string,
+  reason: string,
+  consumedAt: string,
+): Promise<InventoryItemRow | null> {
   return withTransaction(async (client) => {
     await client.query(
       `
@@ -175,8 +190,6 @@ export async function markInventoryItemConsumed(inventoryItemId, reason, consume
   })
 }
 
-/** @returns {Promise<InventoryListQueryResult>} */
-/** @param {InventoryListQueryInput} [queryInput] */
 export async function listInventoryItems({
   page = 1,
   pageSize = 20,
@@ -186,7 +199,7 @@ export async function listInventoryItems({
   batchNo = '',
   inventoryGroupCode = '',
   allowedInventoryGroupCodes = null,
-} = /** @type {InventoryListQueryInput} */ ({})) {
+}: InventoryListQueryInput = {}): Promise<InventoryListQueryResult> {
   const normalizedAllowedInventoryGroupCodes = normalizeInventoryGroupCodes(allowedInventoryGroupCodes)
   if (normalizedAllowedInventoryGroupCodes && normalizedAllowedInventoryGroupCodes.length === 0) {
     return {
@@ -196,8 +209,8 @@ export async function listInventoryItems({
   }
 
   const offset = (page - 1) * pageSize
-  const filters = []
-  const params = []
+  const filters: string[] = []
+  const params: unknown[] = []
 
   if (skuCode) {
     params.push(skuCode)
@@ -230,14 +243,14 @@ export async function listInventoryItems({
   }
 
   const whereClause = filters.length > 0 ? `WHERE ${filters.join(' AND ')}` : ''
-  const totalResult = await query(
+  const totalResult = await query<{ [column: string]: unknown, total: number }>(
     `SELECT COUNT(*)::int AS total FROM inventory_items ii ${whereClause}`,
     params,
   )
 
   params.push(pageSize)
   params.push(offset)
-  const itemsResult = await query(
+  const itemsResult = await query<InventoryItemRow>(
     `${INVENTORY_ITEM_SELECT}
      ${whereClause}
      ORDER BY ii.id DESC
@@ -246,27 +259,25 @@ export async function listInventoryItems({
   )
 
   return {
-    items: /** @type {InventoryItemRow[]} */ (itemsResult.rows),
+    items: itemsResult.rows,
     total: Number(totalResult.rows[0]?.total || 0),
   }
 }
 
-/** @returns {Promise<InventorySkuSuggestionRow[]>} */
-/** @param {InventorySkuSuggestionQueryInput} [queryInput] */
 export async function listInventorySkuSuggestions({
   credentialType = '',
   keyword = '',
   limit = 50,
   inventoryGroupCode = '',
   allowedInventoryGroupCodes = null,
-} = /** @type {InventorySkuSuggestionQueryInput} */ ({})) {
+}: InventorySkuSuggestionQueryInput = {}): Promise<InventorySkuSuggestionRow[]> {
   const normalizedAllowedInventoryGroupCodes = normalizeInventoryGroupCodes(allowedInventoryGroupCodes)
   if (normalizedAllowedInventoryGroupCodes && normalizedAllowedInventoryGroupCodes.length === 0) {
     return []
   }
 
-  const filters = []
-  const params = []
+  const filters: string[] = []
+  const params: unknown[] = []
 
   if (credentialType) {
     params.push(credentialType)
@@ -294,7 +305,7 @@ export async function listInventorySkuSuggestions({
 
   params.push(normalizedLimit)
   const whereClause = filters.length > 0 ? `WHERE ${filters.join(' AND ')}` : ''
-  const result = await query(
+  const result = await query<InventorySkuSuggestionRow>(
     `
       SELECT
         sku_code,
@@ -317,18 +328,17 @@ export async function listInventorySkuSuggestions({
     params,
   )
 
-  return /** @type {InventorySkuSuggestionRow[]} */ (result.rows)
+  return result.rows
 }
 
-/** @param {InventoryCreateItemInput[]} rows */
-export async function createInventoryItems(rows) {
+export async function createInventoryItems(rows: InventoryCreateItemInput[]): Promise<number> {
   let created = 0
 
   for (const row of rows) {
     const payloadJson = JSON.stringify(row.payload || { code: row.displayValue })
     const displayValue = String(row.displayValue || '').trim()
     const inventoryGroupCode = String(row.inventoryGroupCode || '').trim()
-    const result = await query(
+    const result = await query<{ [column: string]: unknown, id: number }>(
       `
         INSERT INTO inventory_items (
           batch_no,
@@ -370,8 +380,8 @@ export async function createInventoryItems(rows) {
 export async function listInventoryGroupCodes({
   keyword = '',
   limit = 100,
-} = {}) {
-  const params = []
+}: InventoryGroupListInput = {}): Promise<string[]> {
+  const params: unknown[] = []
   const filters = [`inventory_group_code <> ''`]
 
   if (keyword) {
@@ -384,7 +394,7 @@ export async function listInventoryGroupCodes({
     : 100
 
   params.push(normalizedLimit)
-  const result = await query(
+  const result = await query<{ [column: string]: unknown, inventory_group_code: string }>(
     `
       SELECT inventory_group_code
       FROM inventory_items
@@ -399,7 +409,7 @@ export async function listInventoryGroupCodes({
   return result.rows.map((row) => String(row.inventory_group_code || '').trim()).filter(Boolean)
 }
 
-function normalizeInventoryGroupCodes(inventoryGroupCodes) {
+function normalizeInventoryGroupCodes(inventoryGroupCodes: InventoryGroupCodesInput): string[] | null {
   if (inventoryGroupCodes == null) {
     return null
   }
@@ -409,8 +419,10 @@ function normalizeInventoryGroupCodes(inventoryGroupCodes) {
     .filter(Boolean)))
 }
 
-/** @returns {Promise<InventoryItemRow | null>} */
-export async function releaseReservedInventoryItem(inventoryItemId, updatedAt) {
+export async function releaseReservedInventoryItem(
+  inventoryItemId: number | string,
+  updatedAt: string,
+): Promise<InventoryItemRow | null> {
   return withTransaction(async (client) => {
     await client.query(
       `
@@ -434,8 +446,12 @@ export async function releaseReservedInventoryItem(inventoryItemId, updatedAt) {
   })
 }
 
-export async function invalidateInventoryItem(inventoryItemId, invalidReason, updatedAt) {
-  const result = await query(
+export async function invalidateInventoryItem(
+  inventoryItemId: number | string,
+  invalidReason: string,
+  updatedAt: string,
+): Promise<InventoryItemRow | null> {
+  const result = await query<{ [column: string]: unknown, id: number }>(
     `
       UPDATE inventory_items
       SET status = 'invalid', invalid_reason = $1, updated_at = $2
@@ -452,7 +468,11 @@ export async function invalidateInventoryItem(inventoryItemId, invalidReason, up
   return getInventoryItemById(inventoryItemId)
 }
 
-export async function invalidateReservedInventoryItem(inventoryItemId, invalidReason, updatedAt) {
+export async function invalidateReservedInventoryItem(
+  inventoryItemId: number | string,
+  invalidReason: string,
+  updatedAt: string,
+): Promise<InventoryItemRow | null> {
   return withTransaction(async (client) => {
     await client.query(
       `
diff --git a/docs/backend-typescript-migration-plan.md b/docs/backend-typescript-migration-plan.md
index 7657fd55..f56b13aa 100644
--- a/docs/backend-typescript-migration-plan.md
+++ b/docs/backend-typescript-migration-plan.md
@@ -231,12 +231,14 @@
 15. repository 第四批已迁移到 `.ts`：
     - `src/repositories/order-repo.ts`
     - `src/repositories/task-inventory-binding-repo.ts`
+16. 核心库存 repository 已迁移到 `.ts`：
+    - `src/repositories/inventory-repo.ts`
 
 ## 下一步建议
 
 第一批继续推进时，建议按这个顺序：
 
-1. 继续迁移剩余核心 repository：`inventory-repo`、`task-repo`
+1. 继续迁移剩余核心 repository：`task-repo`
 2. 拆分并迁移 `runtime.js`，把 env 解析、默认配置加载、配置合并分开
 3. 为 webhook、库存换码、自动发货补测试