author-migration

1#!/usr/bin/env node2// Computes the target-train version options for a migration authoring task3// (SKILL.md section 2). Anchored on the npm dist-tags: a prerelease `next`4// above `latest` is an active prerelease train; anything else means the train5// rolled over and the next cut starts a new minor. Requires the repo's6// node_modules to be installed; `semver` resolves from there.7import { execSync } from 'node:child_process';8import semver from 'semver';9 10function bail(reason) {11  console.error(12    `${reason}; compute the options by hand per SKILL.md section 2.`13  );14  process.exit(1);15}16 17let distTags;18try {19  distTags = JSON.parse(20    execSync('npm view nx dist-tags --json', {21      encoding: 'utf-8',22      timeout: 30_000,23    })24  );25} catch (e) {26  bail(`Could not read the nx dist-tags (${String(e.message).split('\n')[0]})`);27}28const { latest, next } = distTags ?? {};29if (!semver.valid(latest) || !semver.valid(next) || semver.prerelease(latest)) {30  bail(`Unexpected nx dist-tags (latest: ${latest}, next: ${next})`);31}32 33const options = [];34if (semver.prerelease(next) && semver.gt(next, latest)) {35  options.push({36    version: semver.inc(next, 'prerelease'),37    reason: `next prerelease on the active train (next is ${next})`,38    recommended: true,39  });40} else {41  // A stable next above latest (mid-promotion) means the rollover already42  // happened; anchor the new minor on it so the result is not backdated.43  const base = semver.gt(next, latest) ? next : latest;44  options.push({45    version: `${semver.inc(base, 'minor')}-beta.0`,46    reason: `first prerelease of the next minor (train rolled over: next is ${next})`,47    recommended: true,48  });49}50if (semver.major(next) <= semver.major(latest)) {51  options.push({52    version: `${semver.inc(latest, 'major')}-beta.0`,53    reason:54      'next major at beta.0, for breaking work aimed at the upcoming major (the branch, not this field, chooses the ship vehicle: merges only after the train switch)',55    recommended: false,56  });57}58 59console.log(`nx dist-tags: latest ${latest}, next ${next}\n`);60for (const { version, reason, recommended } of options) {61  console.log(`${recommended ? '*' : ' '} ${version}  ${reason}`);62}63console.log(64  '\n* recommended default for non-interactive runs. Interactive runs present every option plus free text (SKILL.md section 2).'65);66