`--json` / `--format json` always indented its streamed result. Agents and
scripts read REA through pipes and redirects, where indentation carries no
information: on real application results it added 16-45% model tokens
(o200k proxy) and 25-73% bytes. The skill's CLI fallback uses `--json`.
Indent only when stdout is a TTY, as `gh --json` does; piped or redirected
JSON is compact. The JSON value, `jsonl`, `--filter-output`,
`--full-output` and the token-window paths are unchanged. `jq .` restores
indentation for files.
Co-authored-by: Claude Opus 5.5 <noreply@anthropic.com>