Summary

Adds a --json flag to release and release-react. When set, the CLI emits a single-line JSON object describing the released package as the last line of stdout; all progress messages route to stderr. The motivation is the upcoming aetherpush/deploy-action GitHub Action, which needs structured outputs (label, package hash, size, etc.) to chain post-release steps without parsing prose with regex.

Behavior

With --json:

• stdout receives exactly one line: a compact JSON object.
• stderr receives all the human-readable progress (Uploading release package..., hermes/signing notices, success line).
• On failure: nothing on stdout, human error on stderr, exit non-zero. Standard UNIX convention.
• Pipes work clean: aether release MyApp ./bundle.js 1.0.0 --json | jq .label.

Without --json: zero change from current behavior.

Schema

The JSON object reuses the Package returned by the server (already typed Promise<Package> on the SDK), so it reflects the post-upload truth — label assigned, hash computed, size measured, description with the [ci=...] bracket already injected by Phase 4's --ci-metadata.

Fields: label, packageHash, size, appVersion, blobUrl, manifestBlobUrl, description, releasedBy, releaseMethod, uploadTime, rollout, isMandatory, isDisabled. Undefined fields are dropped from the JSON.

Design notes

The flag is scoped to release and release-react (declared per-builder, not in addCommonConfiguration). It does not autoset --non-interactive or vice versa — the two flags are orthogonal.

releaseReact already delegates to release at the end of its bundle/hermes/sign chain, so a single JSON emit point in release() covers both commands. The shared progressLog(command, message) helper routes 7 progress sites in the two functions to stderr when command.json is set.

The formatter lives in a small script/utils/release-json.ts module. promote and patch are out of scope for this PR but can adopt the same formatter in roughly three lines each when needed.

Tests

• __tests__/utils/release-json.test.ts: shape with a full package, dropping of undefined fields, single-line guarantee.
• __tests__/command-parser.test.ts: --json absent leaves the field undefined, present sets it true on both release and release-react.
• __tests__/command-executor.test.ts: with --json, the last stdout line parses as JSON and matches schema while the upload notice goes to stderr; without --json, the upload notice stays on stdout and no JSON line appears.

Coverage on release-json.ts: 100% across statements, branches, functions, lines. Suite total 392 tests, all passing.

Type of change

• feat
• fix
• refactor
• chore
• docs

Checklist

• Build and typecheck pass locally (npm run build)
• Tests added or updated (when test infrastructure is wired up)
• Relevant docs updated