Add JSON format support to session destroy for native API clients

This is so that native API clients can get the session record deleted
server-side. They still need to take care of clearing any cookies
they've set in web views.

Co-Authored-By: Claude Opus 4.5 <[email protected]>

Author: rosa

app/controllers/sessions_controller.rb

@@ -20,7 +20,11 @@ def create
 
   def destroy
     terminate_session
-    redirect_to_logout_url
+
+    respond_to do |format|
+      format.html { redirect_to_logout_url }
+      format.json { head :no_content }
+    end
   end
 
   private

docs/API.md

@@ -118,6 +118,22 @@ __Error responses:__
 | `401 Unauthorized` | Invalid `pending_authentication_token` or `code` |
 | `429 Too Many Requests` | Rate limit exceeded |
 
+
+#### Delete server-side session (_log out_)
+
+To log out and destroy the server-side session:
+
+```bash
+curl -X DELETE \
+  -H "Accept: application/json" \
+  -H "Cookie: session_token=eyJfcmFpbHMi..." \
+  https://app.fizzy.do/session
+```
+
+__Response:__
+
+Returns `204 No Content` on success.
+
 ## Caching
 
 Most endpoints return [ETag](https://developer.mozilla.org/en-US/docs/Web/HTTP/Reference/Headers/ETag) and [Cache-Control](https://developer.mozilla.org/en-US/docs/Web/HTTP/Reference/Headers/Cache-Control) headers. You can use these to avoid re-downloading unchanged data.

test/controllers/api_test.rb

@@ -22,6 +22,26 @@ class ApiTest < ActionDispatch::IntegrationTest
     end
   end
 
+  test "logout with user credentials" do
+    identity = identities(:david)
+
+    untenanted do
+      post session_path(format: :json), params: { email_address: identity.email_address }
+      magic_link = MagicLink.last
+
+      assert_difference -> { identity.sessions.count }, +1 do
+        post session_magic_link_path(format: :json), params: { code: magic_link.code, pending_authentication_token: @response.parsed_body["pending_authentication_token"] }
+      end
+      assert cookies[:session_token].present?
+
+      assert_difference -> { identity.sessions.count }, -1 do
+        delete session_path(format: :json)
+      end
+      assert_response :no_content
+      assert_not cookies[:session_token].present?
+    end
+  end
+
   test "authenticate with valid access token" do
     get boards_path(format: :json), env: @davids_bearer_token
     assert_response :success

test/controllers/sessions_controller_test.rb

@@ -117,4 +117,15 @@ class SessionsControllerTest < ActionDispatch::IntegrationTest
       assert_response :unprocessable_entity
     end
   end
+
+  test "destroy via JSON" do
+    sign_in_as :kevin
+
+    untenanted do
+      delete session_path(format: :json)
+
+      assert_response :no_content
+      assert_not cookies[:session_token].present?
+    end
+  end
 end