Agent and non-interactive mode: --no-input, --json everywhere, exit codes

[Interlap01]

What

Agent / non-interactive mode across the CLI.

• Exit codes in one place (internal/exitcode): 0 ok, 1 failure, 2 usage, 3 auth, 4 CI run failed, 5 timeout, 130 interrupted. Errors are tagged where they arise (exitcode.With, or an ExitCode() method on github.RunFailedError, github.APIError/asc.Error for 401). Cobra flag/argument errors and unknown subcommands of a group (builder ios nope, which used to print help and exit 0) exit 2.
• No hidden prompts: global --no-input (also BUILDER_NO_INPUT=1, CI=true, or --json). Every question goes through one helper. With --yes it takes the default. In a terminal it prompts. Otherwise it fails at once with exit 2 and names the flag to pass.
  • init: --project, --ios-path, --flutter-version, --jdk-version, --commit, --build, --yes. --yes takes the detected values but never commits or builds. Missing answers fail before any file is written.
  • signing csr / p12 / setup (manual mode): flags named. csr --yes replaces an existing key.
  • dev flutter|rn|kmp: --device or --yes (first device), --resign/--apple-id with BUILDER_APPLE_ID_PASSWORD, --bundle-id. Without a terminal it takes the newest IPA.
  • auth codemagic|bitrise|apple fail fast off a terminal.
• auth github --token-stdin checks the token with GET /user. A classic token missing repo, workflow or gist is refused (exit 3, not saved, missing scopes named). Fine-grained tokens report no scopes, so they are saved without the check. Off a terminal, the browser flow needs --device-flow.
• --json on auth github|status|logout|apple|codemagic|bitrise, init, ios build (build ID, IPA path/size, run URL, duration; progress on stderr), ios share, ios cancel, signing csr|p12|setup --certificate, mobai ping|install|forward. dev * prints NDJSON session events (device, installed, launched, vm_service/metro) on stdout, and everything else goes to stderr.
• Docs: README section "Using Builder from agents and CI" (flags per command, JSON shapes, exit-code table). CLAUDE.md patterns updated.

Why

Cloud coding agents and CI drive Builder without a TTY. Before this change, init and the dev sessions could hang on promptui, auth github had no token path, and every failure exited 1.

How tested

• go test -race ./... and golangci-lint v2.12.2 (the CI version): clean.
• New tests run each command that used to prompt with stdin not a terminal and a 10s guard against blocking: init, signing csr|p12|setup, auth github|codemagic|apple, dev --skip-install. They also cover the --no-input/BUILDER_NO_INPUT/CI switches with a terminal, the dev device/re-sign/IPA choices against a fake MobAI, auth github --token-stdin with stubbed GitHub checks (plus an httptest test of the scope parsing), JSON shapes (ios build, ios share, init, mobai ping), and exit-code mapping on a test tree and the real command tree.
• No live runs against GitHub, CI providers or devices.

Left out

• update and mobai run-debug have no --json: update prints one line, and run-debug streams app output.
• Failures go to stderr as Error: .... There is no JSON error object on stdout; the exit code carries the category.
• No GH_TOKEN environment fallback for the stored GitHub login. Pipe it with --token-stdin instead.
• ios build on GitHub still installs no signal handler, so Ctrl-C ends the process by signal (shells report 130).