Add Azure OpenAI soft-delete troubleshooting section

Co-authored-by: ianjensenisme <[email protected]>

Author: ianjensenisme

docs/troubleshooting.md

@@ -8,6 +8,21 @@ If you see an InsufficientQuota error mentioning "Tokens Per Minute", the reques
 
 This occurs when Terraform tries to create the private endpoint before the Azure OpenAI (Cognitive Services) account leaves the `Accepted` state; wait until the resource shows `Succeeded` (portal or `az resource show`) and re-run the provisioning (`azd provision`).
 
+## Azure OpenAI resource name already exists error
+
+If you encounter an error like `Code="ResourceNameAlreadyExists" Message="The resource name 'oai-copilot-studio-xyz' is already in use"` during deployment, this typically indicates that an Azure OpenAI resource with the same name exists in a soft-deleted state.
+
+**Symptoms:**
+- Deployment fails with `ResourceNameAlreadyExists` error
+- The resource was previously deleted via `azd down` or Terraform destroy
+- Error occurs within 48 hours of the previous deletion
+
+**Cause:**
+Azure OpenAI (Cognitive Services) resources are soft-deleted by default and remain in a "recently deleted" state for 48 hours. During this retention period, the resource name is reserved and cannot be reused.
+
+**Solution:**
+In CI/CD workflows, soft-deleted resources are automatically purged after `azd down`. For local development, you can manually purge the resource by following the instructions in the [Clean Up section of the README](../README.md#clean-up).
+
 ## Use GitHub Copilot to help troubleshoot
 
 If you're unsure how to fix a deployment error, open the relevant files in VS Code and use GitHub Copilot for suggestions. Copilot can propose TFVARS overrides, sample values, terraform plan snippets, or concise support-request wording; always review and test generated suggestions before applying them.