Summary

Coding agents that run the CLI now get JSON output by default, so they can parse structured results instead of scraping human-formatted tables. I resolve the effective output format once at the TypeScript entrypoint (both the legacy and next roots): an explicit --output / --output-format always wins, otherwise a detected coding agent gets json and everyone else keeps text. For Go-proxied commands this flows down as --output json to the Go subprocess, which renders JSON for the data-returning commands and ignores the flag elsewhere, so no Go changes were needed.

Changes

• Resolve output format from coding-agent detection in both CLI roots, defaulting agents to json when no format is set explicitly.
• Add a shared resolveAgentOutputFormat helper (explicit ?? (agent ? json : text)) reused by both roots, with unit tests.
• Make the --output-format global flag optional so an explicitly-passed format is distinguishable from the default.
• Suppress the agent JSON default whenever the Go-compat -o/--output flag is passed explicitly: -o json|yaml|toml|env already short-circuits inside handlers, and -o pretty now keeps rendering the human table on natively ported commands instead of being overridden to JSON.

Behavior notes

• Humans and CI keep their current output: production telemetry shows ~99.6% of CI invocations carry no coding-agent env signal, so they don't flip.
• Error rendering follows the resolved format. In text mode errors stay as red text on stderr, unchanged. In agent-default JSON mode handler errors emit the existing structured envelope ({"_tag":"Error","error":{code,message}}) on stdout with a non-zero exit code, the same behavior --output-format json already had, so agents get parseable failures instead of prose.
• Interactive prompts already refuse to block in JSON mode (NonInteractiveError), so a detected agent cannot hang on a confirm prompt.
• --help and --version render before the output layer engages and stay text in both roots.
• --agent yes|no overrides detection in both directions for the default-format decision.

Linear

• fixes GROWTH-913