Add bumpy check command for pre-push hook changeset verification

Compares changed files on branch vs base, maps them to packages,
and exits non-zero if any changed packages are missing changesets.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: theoephraim

DIFFERENCES_FROM_CHANGESETS.md

@@ -121,6 +121,12 @@ Custom changelog formatters with full context (release info, changesets, dates).
 
 `bumpy ci check` and `bumpy ci release` handle PR checks and release automation without needing a separate GitHub Action or bot installation. Just `bunx @varlock/bumpy ci check` in any workflow.
 
+### Local changeset verification
+
+`bumpy check` verifies that all changed packages on the current branch have corresponding changesets. Designed for pre-push hooks — compares your branch to the base branch, maps changed files to packages, and exits non-zero if any are missing. No GitHub API needed.
+
+Changesets has no built-in equivalent — users rely on the CI bot comment to catch missing changesets after pushing.
+
 ---
 
 ## Planned / Not Yet Implemented

llms.md

@@ -313,6 +313,20 @@ JSON output shape:
 }
 ```
 
+### `bumpy check`
+
+Verify that all changed packages on the current branch have corresponding changesets. Compares files changed vs the base branch, maps them to managed packages, and exits non-zero if any are missing changesets.
+
+Designed for pre-push hooks — no GitHub API needed.
+
+```yaml
+# lefthook.yml
+pre-push:
+  jobs:
+    - name: bumpy-check
+      run: bunx @varlock/bumpy check
+```
+
 ### `bumpy version`
 
 Apply all pending changesets: bump versions in `package.json`, update `CHANGELOG.md`, delete consumed changeset files. Optionally creates a git commit if `commit: true` in config.

packages/bumpy/src/cli.ts

@@ -89,6 +89,13 @@ async function main() {
         break;
       }
 
+      case 'check': {
+        const rootDir = await findRoot();
+        const { checkCommand } = await import('./commands/check.ts');
+        await checkCommand(rootDir);
+        break;
+      }
+
       case 'ci': {
         const rootDir = await findRoot();
         const subcommand = args[1];
@@ -178,6 +185,7 @@ function printHelp() {
     add                     Create a new changeset
     generate                Generate changeset from conventional commits
     status                  Show pending releases
+    check                   Verify changed packages have changesets (for pre-push hooks)
     version                 Apply changesets and bump versions
     publish                 Publish versioned packages
     ci check                PR check — report pending releases, comment on PR

packages/bumpy/src/commands/check.ts

@@ -0,0 +1,89 @@
+import { relative } from 'node:path';
+import { log, colorize } from '../utils/logger.ts';
+import { loadConfig } from '../core/config.ts';
+import { discoverWorkspace } from '../core/workspace.ts';
+import { readChangesets } from '../core/changeset.ts';
+import { tryRun } from '../utils/shell.ts';
+import type { WorkspacePackage } from '../types.ts';
+
+/**
+ * Local check: detect which packages have changed on this branch
+ * and verify they have corresponding changesets.
+ * Designed for pre-push hooks — no GitHub API needed.
+ */
+export async function checkCommand(rootDir: string): Promise<void> {
+  const config = await loadConfig(rootDir);
+  const { packages } = await discoverWorkspace(rootDir, config);
+  const changesets = await readChangesets(rootDir);
+
+  // Find which packages already have changesets
+  const coveredPackages = new Set<string>();
+  for (const cs of changesets) {
+    for (const release of cs.releases) {
+      coveredPackages.add(release.name);
+    }
+  }
+
+  // Find which packages have changed on this branch vs base
+  const baseBranch = config.baseBranch;
+  const changedFiles = getChangedFiles(rootDir, baseBranch);
+
+  if (changedFiles.length === 0) {
+    log.info('No changed files detected.');
+    return;
+  }
+
+  const changedPackages = findChangedPackages(changedFiles, packages, rootDir);
+
+  if (changedPackages.length === 0) {
+    log.info('No managed packages have changed.');
+    return;
+  }
+
+  // Check which changed packages are missing changesets
+  const missing = changedPackages.filter((name) => !coveredPackages.has(name));
+
+  if (missing.length === 0) {
+    log.success(`All ${changedPackages.length} changed package(s) have changesets.`);
+    return;
+  }
+
+  // Report missing
+  log.warn(`${missing.length} changed package(s) missing changesets:\n`);
+  for (const name of missing) {
+    console.log(`  ${colorize(name, 'yellow')}`);
+  }
+  console.log();
+  log.dim('Run `bumpy add` to create a changeset, or `bumpy add --empty` if no release is needed.');
+  process.exit(1);
+}
+
+/** Get files changed on this branch compared to the base branch */
+function getChangedFiles(rootDir: string, baseBranch: string): string[] {
+  // Try merge-base first (works on branches)
+  const mergeBase = tryRun(`git merge-base HEAD origin/${baseBranch}`, { cwd: rootDir });
+  const ref = mergeBase || `origin/${baseBranch}`;
+  const diff = tryRun(`git diff --name-only ${ref}`, { cwd: rootDir });
+  if (!diff) return [];
+  return diff.split('\n').filter(Boolean);
+}
+
+/** Map changed files to the packages they belong to */
+function findChangedPackages(
+  changedFiles: string[],
+  packages: Map<string, WorkspacePackage>,
+  rootDir: string,
+): string[] {
+  const changed = new Set<string>();
+
+  for (const file of changedFiles) {
+    for (const [name, pkg] of packages) {
+      const pkgRelDir = relative(rootDir, pkg.dir);
+      if (file.startsWith(pkgRelDir + '/')) {
+        changed.add(name);
+      }
+    }
+  }
+
+  return [...changed];
+}