feat: indent echo responses for readable evidence

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

.playwright-mcp/page-2026-09-03T06-48-11-954Z.yml

@@ -0,0 +1 @@
+- generic [active] [ref=f3e1]: "{\"headers\":{\"host\":[\"app1.hyeonworks.com\"],\"user-agent\":[\"Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/152.0.0.0 Safari/537.36\"],\"accept\":[\"text/html,application/xhtml+xml,application/xml;q=0.9,image/avif,image/webp,image/apng,*/*;q=0.8,application/signed-exchange;v=b3;q=0.7\"],\"accept-encoding\":[\"gzip, deflate, br, zstd\"],\"accept-language\":[\"en-US,en;q=0.9\"],\"priority\":[\"u=0, i\"],\"sec-ch-ua\":[\"\\\"Chromium\\\";v=\\\"152\\\", \\\"Not?A_Brand\\\";v=\\\"24\\\", \\\"Google Chrome\\\";v=\\\"152\\\"\"],\"sec-ch-ua-mobile\":[\"?0\"],\"sec-ch-ua-platform\":[\"\\\"Linux\\\"\"],\"sec-fetch-dest\":[\"document\"],\"sec-fetch-mode\":[\"navigate\"],\"sec-fetch-site\":[\"none\"],\"sec-fetch-user\":[\"?1\"],\"upgrade-insecure-requests\":[\"1\"],\"x-forwarded-host\":[\"app1.hyeonworks.com\"],\"x-forwarded-port\":[\"443\"],\"x-forwarded-proto\":[\"https\"],\"x-forwarded-server\":[\"traefik-697889c85-g7xpp\"],\"x-real-ip\":[\"100.123.124.30\"]},\"remoteAddr\":\"100.123.124.30\",\"localAddr\":\"10.42.0.10\",\"scheme\":\"https\",\"secure\":true,\"serverName\":\"app1.hyeonworks.com\",\"serverPort\":443,\"requestUrl\":\"https://app1.hyeonworks.com/api/echo\"}"

backend/src/main/resources/application.yml

@@ -9,6 +9,11 @@ server:
 spring:
   application:
     name: keycloak-pattern-api
+  jackson:
+    serialization:
+      # /api/echo is read by humans and captured as evidence screenshots, so the
+      # response is indented rather than relying on a browser's JSON viewer.
+      indent-output: true
   security:
     oauth2:
       resourceserver: