diff --git a/UAT_PLAYBOOK.md b/UAT_PLAYBOOK.md
index 42a0b07..cb02d20 100644
--- a/UAT_PLAYBOOK.md
+++ b/UAT_PLAYBOOK.md
@@ -38,6 +38,7 @@ GroomBook API is a Hono-based REST service (TypeScript/Node.js) powering the pet
 | TC-API-1.13 | Name fallback — user.name present | Auto-provision where Better-Auth user has name set | Staff name = user.name value from user table |
 | TC-API-1.14 | Name fallback — no name, email present | Auto-provision where Better-Auth user has name = null, email = "test@example.com" | Staff name = "test" (email prefix before @) |
 | TC-API-1.15 | Name fallback — no name, no email | Auto-provision where Better-Auth user has name = null, email = null | Staff name = "Unknown" |
+| TC-API-1.16 | OIDC login — Terraform-provisioned user | Initiate OIDC login as any UAT persona (uat-super, uat-groomer, uat-customer, uat-tester), complete authentik callback | 200 OK, session created — no account_not_linked error |
 
 ### 4.2 Client Management
 
diff --git a/src/lib/auth.ts b/src/lib/auth.ts
index 209e9d6..9e78740 100644
--- a/src/lib/auth.ts
+++ b/src/lib/auth.ts
@@ -251,6 +251,10 @@ export async function initAuth(): Promise<void> {
         },
       },
       account: {
+        accountLinking: {
+          enabled: true,
+          trustedProviders: ["authentik"],
+        },
         storeStateStrategy: "cookie" as const,
       },
       emailAndPassword: {