feat: Add IndexNow sitemap notification to deployment

.github/workflows/Build-Test-And-Deploy.yml

@@ -238,6 +238,49 @@ jobs:
           git tag -f "deployed/prod/${{ github.sha }}"
           git push origin "deployed/prod/${{ github.sha }}" --force
 
+      - name: Notify IndexNow of Sitemap Update
+        continue-on-error: true
+        env:
+          INDEXNOW_API_KEY: ${{ secrets.INDEXNOW_API_KEY }}
+        run: |
+          # IndexNow Protocol: Notifies search engines (Bing, Yandex, Naver) of content updates.
+          # See: https://www.indexnow.org/documentation
+          #
+          # Domain ownership is verified via a key file hosted at:
+          #   https://essentialcsharp.com/{key}.txt  (served from wwwroot/{key}.txt)
+          # The file must contain exactly the key value. Without it, submissions return HTTP 403.
+          #
+          # We fetch the live sitemap (app is confirmed up after smoke test) and extract all <loc>
+          # URLs to submit as actual content URLs per the IndexNow spec.
+
+          # Fetch the live sitemap and extract all <loc> URLs into a newline-delimited list
+          SITEMAP=$(curl -sf "https://essentialcsharp.com/sitemap.xml")
+          if [ -z "$SITEMAP" ]; then
+            echo "::warning::Could not fetch sitemap; skipping IndexNow submission."
+            exit 0
+          fi
+
+          # Build a JSON array from <loc>...</loc> entries
+          URL_ARRAY=$(echo "$SITEMAP" \
+            | grep -oP '(?<=<loc>)[^<]+' \
+            | jq -Rn '[inputs]')
+
+          URL_COUNT=$(echo "$URL_ARRAY" | jq 'length')
+          echo "Submitting $URL_COUNT URLs to IndexNow..."
+
+          RESPONSE=$(curl -s -o /dev/null -w "%{http_code}" -X POST https://api.indexnow.org/indexnow \
+            -H "Content-Type: application/json; charset=utf-8" \
+            -d "{
+              \"host\": \"essentialcsharp.com\",
+              \"key\": \"$INDEXNOW_API_KEY\",
+              \"urlList\": $URL_ARRAY
+            }")
+
+          echo "IndexNow response: HTTP $RESPONSE"
+          if [ "$RESPONSE" != "200" ] && [ "$RESPONSE" != "202" ]; then
+            echo "::warning::IndexNow submission returned HTTP $RESPONSE (200/202 = success, 202 = key validation pending)."
+          fi
+
       - name: Logout of Azure CLI
         if: always()
         uses: azure/CLI@v3

EssentialCSharp.Web/wwwroot/6b397fbb613bfbacb059e4972cf3ec15.txt

@@ -0,0 +1 @@
+6b397fbb613bfbacb059e4972cf3ec15

README.md

@@ -11,3 +11,37 @@ For any bugs, questions, or anything else with specifically the code found insid
 For information on setting up your local development environment, please see the [Getting Started Guide](docs/getting-started.md).
 
 Please use issues or discussions to report issues found.
+
+## IndexNow Setup (Production Deployment)
+
+The deployment workflow notifies search engines (Bing, Yandex, Naver) of content updates via the [IndexNow protocol](https://www.indexnow.org/). After each successful production deploy the workflow fetches the live `sitemap.xml`, extracts all content URLs, and submits them in a single batch POST to IndexNow.
+
+### How It Works
+
+1. After the smoke test confirms the app is live, the workflow fetches `https://essentialcsharp.com/sitemap.xml`.
+2. All `<loc>` URLs are extracted and POSTed to `https://api.indexnow.org/indexnow`.
+3. IndexNow distributes those URLs to all participating search engines (Bing, Yandex, Naver, etc.).
+
+### Setup Requirements
+
+#### 1. Key Verification File (already committed)
+IndexNow requires domain ownership proof via a publicly accessible `.txt` file at the root of the domain:
+- The key file lives at `EssentialCSharp.Web/wwwroot/{key}.txt`
+- The filename and file content are the same value (the key itself)
+- ASP.NET Core's static file middleware serves it at `https://essentialcsharp.com/{key}.txt`
+- IndexNow crawls that URL to verify domain ownership before accepting submissions
+- Without this file, all submissions return HTTP 403
+
+The key file is intentionally public — that is by design. The "security" is that only the domain owner can host a file at that path.
+
+#### 2. GitHub Secret
+Store the key value in GitHub repository secrets as `INDEXNOW_API_KEY`. The workflow reads it from there — the secret value must match the key filename/content committed to the repo.
+
+Go to: **GitHub repo → Settings → Secrets and variables → Actions → New repository secret**
+- Name: `INDEXNOW_API_KEY`
+- Value: the key string (same value as the `.txt` filename in `wwwroot/`)
+
+### Important Notes
+- The IndexNow step uses `continue-on-error: true` — a submission failure will never block a deployment
+- Submitting all sitemap URLs on every deploy is intentional; IndexNow has no hard rate limit for batch submissions and the full URL list ensures nothing is missed
+- To rotate the key: generate a new hex string, add a new `wwwroot/{newkey}.txt`, update the GitHub Secret, and remove the old `.txt` file