diff --git a/.github/workflows/apollo-check.yml b/.github/workflows/apollo-check.yml
new file mode 100644
index 0000000..867c22d
--- /dev/null
+++ b/.github/workflows/apollo-check.yml
@@ -0,0 +1,24 @@
+name: Apollo Check
+on:
+  pull_request:
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    env:
+      APOLLO_VCS_BRANCH: ${{ github.head_ref }}
+      APOLLO_VCS_COMMIT: ${{ github.event.pull_request.head.sha }}
+    steps:
+      - uses: actions/checkout@v4
+      - uses: apollographql-gh-actions/install-rover@v1
+      - uses: apollographql-gh-actions/rover-subgraph-lint@v1
+        with:
+          apollo-key: ${{ secrets.APOLLO_KEY }}
+          graph-ref: ${{ secrets.APOLLO_GRAPH_REF }}
+          name: github
+          schema: ./github.graphql
+      - uses: apollographql-gh-actions/rover-subgraph-check@v1
+        with:
+          apollo-key: ${{ secrets.APOLLO_KEY }}
+          graph-ref: ${{ secrets.APOLLO_GRAPH_REF }}
+          name: github
+          schema: ./github.graphql
diff --git a/.github/workflows/apollo-publish.yml b/.github/workflows/apollo-publish.yml
new file mode 100644
index 0000000..774bc27
--- /dev/null
+++ b/.github/workflows/apollo-publish.yml
@@ -0,0 +1,19 @@
+name: Apollo Publish
+on:
+  push:
+    branches:
+      - main
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    environment: apollo
+    steps:
+      - uses: actions/checkout@v4
+      - uses: apollographql-gh-actions/install-rover@v1
+      - uses: apollographql-gh-actions/rover-subgraph-publish@v1
+        with:
+          apollo-key: ${{ secrets.APOLLO_KEY }}
+          graph-ref: ${{ secrets.APOLLO_GRAPH_REF }}
+          name: github
+          schema: ./github.graphql
+          no-url: true
diff --git a/github.graphql b/github.graphql
new file mode 100644
index 0000000..0c01e6f
--- /dev/null
+++ b/github.graphql
@@ -0,0 +1,43 @@
+extend schema
+  @link(url: "https://specs.apollo.dev/federation/v2.10", import: ["@key"])
+  @link(
+    url: "https://specs.apollo.dev/connect/v0.1"
+    import: ["@connect", "@source"]
+  )
+  @source(
+    name: "github"
+    http: {
+      baseURL: "https://api.github.com"
+      headers: [
+        { name: "Accept", value: "application/vnd.github+json" }
+        { name: "User-Agent", value: "{$config.agent}" }
+        { name: "Authorization", value: "token {$config.token}" }
+      ]
+    }
+  )
+
+type Query {
+  "All trees in the leetcode-study repository"
+  gitTrees: [GitTree]!
+    @connect(
+      source: "github"
+      # https://docs.github.com/en/rest/git/trees#get-a-tree
+      http: {
+        GET: "/repos/DaleStudy/leetcode-study/git/trees/main?recursive=1"
+      }
+      selection: """
+      $.tree {
+        type
+        path
+      }
+      """
+    )
+}
+
+"A file or directory in the Git repository"
+type GitTree {
+  "The type of the node"
+  type: String!
+  "The path of the node"
+  path: String!
+}
diff --git a/products.graphql b/products.graphql
deleted file mode 100644
index cda65e2..0000000
--- a/products.graphql
+++ /dev/null
@@ -1,58 +0,0 @@
-# This schema uses Apollo Connectors, a declarative programming model for
-# GraphQL that allows you to plug in your existing REST services directly into
-# a graph. To learn more, visit Apollo's documentation: 🔗https://www.apollographql.com/docs/graphos/schema-design/connectors
-
-# Guided tutorial: 🔗 https://www.apollographql.com/docs/graphos/get-started/guides/rest
-
-extend schema
-  @link( # Enable this schema to use Apollo Federation features
-    url: "https://specs.apollo.dev/federation/v2.10"
-  )
-  @link( # Enable this schema to use Apollo Connectors
-    url: "https://specs.apollo.dev/connect/v0.1"
-    import: ["@connect", "@source"]
-  )
-
-# A @source directive defines a shared data source for multiple Connectors.
-# ✏️ Replace the `name` and `baseURL` of this @source with your own REST API.
-@source(
-  name: "ecomm"
-  # A @source directive defines a shared data source for multiple Connectors.
-  http: {
-    baseURL: "https://ecommerce.demo-api.apollo.dev/"
-    headers: [
-      # If your API requires headers, add them here and in your router.yaml file.
-      { name: "name", value: "{$config.apiKey}" }
-    ]
-  }
-)
-
-# ✏️ Replace this example type with your own object type.
-type Product {
-  id: ID!
-  name: String
-  description: String
-}
-
-# ✏️ Set up your Query field with the endpoint that returns the data you want.
-
-type Query {
-  # The Query.products field uses @connect to connect to the /products endpoint in the "ecomm" source.
-  # To check out the JSON response for this endpoint, go to 🔗 https://ecommerce.demo-api.apollo.dev/products.
-  products: [Product]
-    # A @connect directive defines the API data source of a GraphQL schema field.
-    @connect(
-      source: "ecomm"
-      http: { GET: "/products" } # GET, POST, PUT, PATCH, DELETE.
-      # Use @connect for any field that should be resolved by your REST API endpoints.
-      # Use the selection argument to map fields from the JSON response to the type.
-      # You can do more with this selection mapping. Lean more at 🔗 https://www.apollographql.com/docs/graphos/schema-design/connectors/responses
-      selection: """
-      $.products {
-        id
-        name
-        description
-      }
-      """
-    )
-}