feat(info): add parent-relative diff output

README.md

@@ -280,12 +280,15 @@ dub bottom
 
 ### `dub info` and `dub branch info`
 
-Show tracked metadata for a branch.
+Show tracked metadata for a branch, optionally including the parent-relative diff.
 
 ```bash
 # current branch
 dub info
 
+# current branch with parent-relative diff
+dub info --diff
+
 # explicit branch
 dub info feat/auth-login
 

apps/docs/content/docs/commands/log.mdx

@@ -49,6 +49,9 @@ For detailed metadata about a specific branch:
 # Current branch
 dub info
 
+# Current branch with parent-relative diff
+dub info --diff
+
 # Explicit branch
 dub info feat/auth-login
 ```

packages/cli/src/commands/branch.test.ts

@@ -1,6 +1,7 @@
+import * as fs from 'node:fs';
 import { afterEach, beforeEach, describe, expect, it } from 'vitest';
 import { createTestRepo, gitInRepo } from '../../test/helpers';
-import { branchInfo, formatBranchInfo } from './branch';
+import { branchInfo, branchInfoOutput, formatBranchInfo } from './branch';
 import { create } from './create';
 import { init } from './init';
 
@@ -100,4 +101,47 @@ describe('branch info', () => {
     expect(untracked).toContain('Tracked: no');
     expect(untracked).toContain('not tracked by DubStack');
   });
+
+  it('includes a parent-relative diff when requested', async () => {
+    await create('feat/a', dir);
+    await create('feat/b', dir);
+    await gitInRepo(dir, ['checkout', 'feat/b']);
+
+    await fs.promises.writeFile(`${dir}/feature.txt`, 'hello from feat/b\n');
+    await gitInRepo(dir, ['add', 'feature.txt']);
+    await gitInRepo(dir, ['commit', '-m', 'feat: add branch diff fixture']);
+
+    const output = await branchInfoOutput(dir, undefined, { diff: true });
+    expect(output).toContain('Branch: feat/b');
+    expect(output).toContain('Diff vs feat/a:');
+    expect(output).toContain('diff --git a/feature.txt b/feature.txt');
+  });
+
+  it('shows an explicit marker when there are no changes relative to the parent', async () => {
+    await create('feat/a', dir);
+    await create('feat/b', dir);
+
+    const output = await branchInfoOutput(dir, undefined, { diff: true });
+    expect(output).toContain('Diff vs feat/a:');
+    expect(output).toContain('(no changes)');
+  });
+
+  it('explains that root branches do not have a parent-relative diff', async () => {
+    await create('feat/a', dir);
+    await gitInRepo(dir, ['checkout', 'main']);
+
+    const output = await branchInfoOutput(dir, 'main', { diff: true });
+    expect(output).toContain('Branch: main');
+    expect(output).toContain('Diff: unavailable for stack root branches.');
+  });
+
+  it('explains that untracked branches cannot show a dubstack diff', async () => {
+    await gitInRepo(dir, ['checkout', '-b', 'rogue']);
+
+    const output = await branchInfoOutput(dir, undefined, { diff: true });
+    expect(output).toContain('Branch: rogue');
+    expect(output).toContain(
+      'Diff: unavailable because this branch is not tracked by DubStack.',
+    );
+  });
 });

packages/cli/src/commands/branch.ts

@@ -1,4 +1,4 @@
-import { getCurrentBranch } from '../lib/git';
+import { getCurrentBranch, getDiffBetween } from '../lib/git';
 import { findStackForBranch, readState, type Stack } from '../lib/state';
 
 export interface BranchInfoResult {
@@ -80,3 +80,45 @@ export function formatBranchInfo(info: BranchInfoResult): string {
     `Children: ${childrenLabel}`,
   ].join('\n');
 }
+
+export interface BranchInfoOutputOptions {
+  diff?: boolean;
+}
+
+/**
+ * Formats branch info and optionally appends a parent-relative git diff.
+ */
+export async function branchInfoOutput(
+  cwd: string,
+  branchName?: string,
+  options: BranchInfoOutputOptions = {},
+): Promise<string> {
+  const info = await branchInfo(cwd, branchName);
+  const summary = formatBranchInfo(info);
+
+  if (!options.diff) {
+    return summary;
+  }
+
+  if (!info.tracked) {
+    return [
+      summary,
+      '',
+      'Diff: unavailable because this branch is not tracked by DubStack.',
+    ].join('\n');
+  }
+
+  if (!info.parent) {
+    return [summary, '', 'Diff: unavailable for stack root branches.'].join(
+      '\n',
+    );
+  }
+
+  const diff = await getDiffBetween(info.parent, info.currentBranch, cwd);
+  return [
+    summary,
+    '',
+    `Diff vs ${info.parent}:`,
+    diff.trim().length > 0 ? diff.trimEnd() : '(no changes)',
+  ].join('\n');
+}

packages/cli/src/index.ts

@@ -22,7 +22,7 @@ import { createRequire } from 'node:module';
 import chalk from 'chalk';
 import { Command } from 'commander';
 import { abortCommand } from './commands/abort';
-import { branchInfo, formatBranchInfo } from './commands/branch';
+import { branchInfoOutput } from './commands/branch';
 import {
   checkout,
   interactiveCheckout,
@@ -76,6 +76,15 @@ const { version } = require('../package.json') as { version: string };
 
 const program = new Command();
 
+async function showInfo(
+  branch: string | undefined,
+  options: { diff?: boolean },
+): Promise<void> {
+  console.log(
+    await branchInfoOutput(process.cwd(), branch, { diff: options.diff }),
+  );
+}
+
 program
   .name('dub')
   .description('Manage stacked diffs (dependent git branches) with ease')
@@ -329,20 +338,16 @@ program
     new Command('info')
       .description('Show tracked stack info for the current branch')
       .argument('[branch]', 'Branch to inspect (defaults to current branch)')
-      .action(async (branch?: string) => {
-        const info = await branchInfo(process.cwd(), branch);
-        console.log(formatBranchInfo(info));
-      }),
+      .option('-d, --diff', 'Show the parent-relative git diff for the branch')
+      .action(showInfo),
   );
 
 program
   .command('info')
   .argument('[branch]', 'Branch to inspect (defaults to current branch)')
+  .option('-d, --diff', 'Show the parent-relative git diff for the branch')
   .description('Show tracked stack info for a branch')
-  .action(async (branch?: string) => {
-    const info = await branchInfo(process.cwd(), branch);
-    console.log(formatBranchInfo(info));
-  });
+  .action(showInfo);
 
 program
   .command('track')