diff --git a/.github/workflows/collect-prs.yml b/.github/workflows/collect-prs.yml
index b420cea..18842f9 100644
--- a/.github/workflows/collect-prs.yml
+++ b/.github/workflows/collect-prs.yml
@@ -1,75 +1,102 @@
-# This workflow will build a .NET project
-
-name: collect dotnet-runtime PRs
-
-on:
-  schedule:
-    - cron: '0 0 * * *'
-  workflow_dispatch: # Allow manual trigger
-
-concurrency:
-  group: "pages"
-  cancel-in-progress: true
-
-jobs:
-  summarize:
-    runs-on: ubuntu-latest
-    permissions:
-      contents: write
-    timeout-minutes: 70 # Message Batches: up to 40 min wait (Program.cs) + one-by-one fallback
-    outputs:
-      has_changes: ${{ steps.commit.outputs.has_changes }}
-    steps:
-    - uses: actions/checkout@9c091bb21b7c1c1d1991bb908d89e4e9dddfe3e0 # v7.0.0
-    - name: Setup .NET
-      uses: prozolic/Actions/.github/actions/setup-dotnet@main
-      with:
-        dotnet-version: 10.0.x
-    - name: Restore dependencies
-      run: dotnet restore
-    - name: Build
-      run: dotnet build -c Release
-    - name: configure-pages@v4 latest PRs and create PRs.
-      run: dotnet run --project ./src/PRDigest.NET/PRDigest.NET.csproj --no-launch-profile -c Release ./archives ./outputs -g
-      env:
-        GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
-        ANTHROPIC_API_KEY: ${{ secrets.ANTHROPIC_API_KEY }}
-    - name: Commit and push changes
-      id: commit
-      run: |
-        git config --local user.email "41898282+github-actions[bot]@users.noreply.github.com"
-        git config --local user.name "github-actions[bot]"
-        git add ./archives
-
-        if git diff --quiet && git diff --staged --quiet; then
-          echo "has_changes=false" >> "$GITHUB_OUTPUT"
-        else
-          git commit -m "Summarize latest PRs by github-actions[bot]" && git push origin main
-          echo "has_changes=true" >> "$GITHUB_OUTPUT"
-        fi
-    - name: Upload artifact
-      uses: actions/upload-pages-artifact@fc324d3547104276b827a68afc52ff2a11cc49c9 # v5.0.0
-      with:
-        path: ./outputs/
-
-  deploy:
-    needs: summarize
-    permissions:
-      contents: read
-      pages: write
-      id-token: write
-    environment:
-      name: github-pages
-      url: ${{steps.deployment.outputs.page_url}}
-    runs-on: ubuntu-latest
-    steps:
-      - name: Deploy
-        id: deployment
-        uses: actions/deploy-pages@cd2ce8fcbc39b97be8ca5fce6e763baed58fa128 # v5.0.0
-
-  # NOTE: push with GITHUB_TOKEN won't invoke the event,
-  #       as a workaround, directly call the action.
-  release:
-    needs: [summarize, deploy]
-    if: needs.summarize.outputs.has_changes == 'true'
-    uses: ./.github/workflows/create-release.yml
+# This workflow will build a .NET project
+
+name: collect dotnet-runtime PRs
+
+on:
+  schedule:
+    - cron: '0 0 * * *'
+  workflow_dispatch: # Allow manual trigger
+
+concurrency:
+  group: "pages"
+  cancel-in-progress: true
+
+jobs:
+  summarize:
+    runs-on: ubuntu-latest
+    permissions:
+      contents: write
+      id-token: write # GitHub OIDC token for Workload Identity Federation with the Claude API
+    timeout-minutes: 70 # Message Batches: up to 40 min wait (Program.cs) + one-by-one fallback
+    outputs:
+      has_changes: ${{ steps.commit.outputs.has_changes }}
+    steps:
+    - uses: actions/checkout@9c091bb21b7c1c1d1991bb908d89e4e9dddfe3e0 # v7.0.0
+    - name: Setup .NET
+      uses: prozolic/Actions/.github/actions/setup-dotnet@main
+      with:
+        dotnet-version: 10.0.x
+    - name: Restore dependencies
+      run: dotnet restore
+    - name: Build
+      run: dotnet build -c Release
+    - name: configure-pages@v4 latest PRs and create PRs.
+      run: |
+        fetch_identity_token() {
+          local token
+          token=$(curl -fsS -H "Authorization: Bearer $ACTIONS_ID_TOKEN_REQUEST_TOKEN" \
+            "$ACTIONS_ID_TOKEN_REQUEST_URL&audience=https://api.anthropic.com" | jq -er .value) &&
+          printf '%s' "$token" > "$ANTHROPIC_IDENTITY_TOKEN_FILE.tmp" &&
+          mv "$ANTHROPIC_IDENTITY_TOKEN_FILE.tmp" "$ANTHROPIC_IDENTITY_TOKEN_FILE"
+        }
+        fetch_identity_token
+
+        # A GitHub ID token expires about 5 minutes after it is issued, while this step can run
+        # for over 40 minutes (Message Batches). The SDK re-reads the file whenever it refreshes
+        # its Anthropic access token, so keep the file fresh in the background.
+        # Every 60 s: an Anthropic token lives at most twice the JWT's remaining lifetime and is
+        # refreshed 120 s before expiry, and a JWT (jti) can be exchanged only once, so a staler
+        # file could be read again by the next refresh (jti_reused).
+        while sleep 60; do
+          fetch_identity_token || echo "::warning::Failed to refresh the GitHub OIDC token"
+        done &
+        refresher=$!
+        trap 'kill "$refresher"' EXIT
+
+        dotnet run --project ./src/PRDigest.NET/PRDigest.NET.csproj --no-launch-profile -c Release ./archives ./outputs -g
+      env:
+        GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+        ANTHROPIC_FEDERATION_RULE_ID: ${{ secrets.ANTHROPIC_FEDERATION_RULE_ID }}
+        ANTHROPIC_ORGANIZATION_ID: ${{ secrets.ANTHROPIC_ORGANIZATION_ID }}
+        ANTHROPIC_SERVICE_ACCOUNT_ID: ${{ secrets.ANTHROPIC_SERVICE_ACCOUNT_ID }}
+        ANTHROPIC_WORKSPACE_ID: ${{ secrets.ANTHROPIC_WORKSPACE_ID }}
+        ANTHROPIC_IDENTITY_TOKEN_FILE: ${{ runner.temp }}/gha-jwt
+    - name: Commit and push changes
+      id: commit
+      run: |
+        git config --local user.email "41898282+github-actions[bot]@users.noreply.github.com"
+        git config --local user.name "github-actions[bot]"
+        git add ./archives
+
+        if git diff --quiet && git diff --staged --quiet; then
+          echo "has_changes=false" >> "$GITHUB_OUTPUT"
+        else
+          git commit -m "Summarize latest PRs by github-actions[bot]" && git push origin main
+          echo "has_changes=true" >> "$GITHUB_OUTPUT"
+        fi
+    - name: Upload artifact
+      uses: actions/upload-pages-artifact@fc324d3547104276b827a68afc52ff2a11cc49c9 # v5.0.0
+      with:
+        path: ./outputs/
+
+  deploy:
+    needs: summarize
+    permissions:
+      contents: read
+      pages: write
+      id-token: write
+    environment:
+      name: github-pages
+      url: ${{steps.deployment.outputs.page_url}}
+    runs-on: ubuntu-latest
+    steps:
+      - name: Deploy
+        id: deployment
+        uses: actions/deploy-pages@cd2ce8fcbc39b97be8ca5fce6e763baed58fa128 # v5.0.0
+
+  # NOTE: push with GITHUB_TOKEN won't invoke the event,
+  #       as a workaround, directly call the action.
+  release:
+    needs: [summarize, deploy]
+    if: needs.summarize.outputs.has_changes == 'true'
+    uses: ./.github/workflows/create-release.yml
diff --git a/src/PRDigest.NET/Program.cs b/src/PRDigest.NET/Program.cs
index f38a1e2..440ed70 100644
--- a/src/PRDigest.NET/Program.cs
+++ b/src/PRDigest.NET/Program.cs
@@ -341,7 +341,7 @@ async ValueTask SummarizeSequentiallyAsync(IAnthropicClient client, PullRequestI
 
 IAnthropicClient CreateAnthropicClient()
 {
-    // Configures ANTHROPIC_API_KEY.
+    // Configures ANTHROPIC_API_KEY (local) or Workload Identity Federation (ANTHROPIC_IDENTITY_TOKEN_FILE etc., GitHub Actions).
     AnthropicClient anthropicClient = new();
     return anthropicClient.WithOptions(options => options with
     {