From 13f5220f90ff59fb5936f5c159c6baea478cb098 Mon Sep 17 00:00:00 2001
From: josh-hemphill <j1.robofan@gmail.com>
Date: Tue, 11 Nov 2025 19:13:56 -0800
Subject: [PATCH] feat: support limiting analyzed commits by path

Passing paths to the end of the git log call, allows analyzing commits on a package-by-package basis in a monorepo
---
 src/cli.ts      |  1 +
 src/config.ts   |  3 +++
 src/generate.ts |  2 +-
 src/git.ts      | 34 ++++++++++++++++++++++++++++++++++
 src/types.ts    |  6 ++++++
 5 files changed, 45 insertions(+), 1 deletion(-)

diff --git a/src/cli.ts b/src/cli.ts
index 74993b4..6def3c6 100644
--- a/src/cli.ts
+++ b/src/cli.ts
@@ -28,6 +28,7 @@ cli
   .option('--group', 'Nest commit messages under their scopes')
   .option('--dry', 'Dry run')
   .option('--assets <paths...>', 'Files to upload as assets to the release. Use quotes to prevent shell glob expansion, e.g., "--assets \'dist/*.js\'"')
+  .option('--commit-paths [paths...]', 'Paths to filter commits by. If true, CWD will be used as the path')
   .help()
 
 async function readTokenFromGitHubCli() {
diff --git a/src/config.ts b/src/config.ts
index dd596b0..5e89eca 100644
--- a/src/config.ts
+++ b/src/config.ts
@@ -45,6 +45,9 @@ export async function resolveConfig(options: ChangelogOptions) {
   // @ts-expect-error backward compatibility
   config.releaseRepo = config.releaseRepo || config.releaseGithub || config.repo
   config.prerelease = config.prerelease ?? isPrerelease(config.to)
+  config.commitPaths = config.commitPaths ?? []
+  if (config.commitPaths === true)
+    config.commitPaths = [config.cwd ?? process.cwd()]
 
   if (typeof config.repo !== 'string')
     throw new Error(`Invalid GitHub repository, expected a string but got ${JSON.stringify(config.repo)}`)
diff --git a/src/generate.ts b/src/generate.ts
index f908728..8e14b6f 100644
--- a/src/generate.ts
+++ b/src/generate.ts
@@ -1,5 +1,5 @@
 import type { ChangelogOptions } from './types'
-import { getGitDiff } from 'changelogen'
+import { getGitDiff } from './git'
 import { resolveConfig } from './config'
 import { resolveAuthors } from './github'
 import { generateMarkdown } from './markdown'
diff --git a/src/git.ts b/src/git.ts
index c530262..785242a 100644
--- a/src/git.ts
+++ b/src/git.ts
@@ -1,3 +1,4 @@
+import { RawGitCommit } from 'changelogen'
 import semver from 'semver'
 
 export async function getGitHubRepo(baseUrl: string) {
@@ -79,6 +80,39 @@ export async function getLastMatchingTag(
   return tag
 }
 
+export async function getGitDiff(
+  from: string,
+  to: string,
+  paths: string[] = [],
+): Promise<RawGitCommit[]> {
+  // https://git-scm.com/docs/pretty-formats
+  const r = await execCommand(
+    'git',
+    [
+      '--no-pager', 'log',
+      `${from ? `${from}...` : ''}${to}`,
+      '--pretty="----%n%s|%h|%an|%ae%n%b"',
+      '--name-status',
+      ...(paths.length > 0 ? ['--', ...paths] : []),
+    ],
+  );
+  return r
+    .split("----\n")
+    .splice(1)
+    .map((line) => {
+      const [firstLine, ..._body] = line.split("\n");
+      const [message, shortHash, authorName, authorEmail] =
+        firstLine.split("|");
+      const r: RawGitCommit = {
+        message,
+        shortHash,
+        author: { name: authorName, email: authorEmail },
+        body: _body.join("\n"),
+      };
+      return r;
+    });
+}
+
 export async function isRefGitTag(to: string) {
   const { execa } = await import('execa')
   try {
diff --git a/src/types.ts b/src/types.ts
index ed6e261..fa1b83c 100644
--- a/src/types.ts
+++ b/src/types.ts
@@ -100,6 +100,12 @@ export interface ChangelogOptions extends Partial<ChangelogenOptions> {
    * `--assets path1,path2` or `--assets path1 --assets path2`
    */
   assets?: string[] | string
+
+  /**
+   * Paths to filter commits by
+   * If true, CWD will be used as the path
+   */
+  commitPaths?: string[] | true
 }
 
 export type ResolvedChangelogOptions = Required<ChangelogOptions>