All search endpoints accept ?format=json|markdown|text|ndjson (default:
json). Accept header negotiation also works (text/markdown, text/plain,
application/x-ndjson). Non-JSON formats skip the response cache to
avoid polluting the JSON cache key. Markdown output is optimised for
n8n Slack/email nodes; text output reduces token count ~25-30% vs JSON
for LLM grounding pipelines; NDJSON emits one result per line.