diff --git a/dev-packages/cli/src/commands/check-header.ts b/dev-packages/cli/src/commands/check-header.ts
index 3d7e3cf..38bffc1 100644
--- a/dev-packages/cli/src/commands/check-header.ts
+++ b/dev-packages/cli/src/commands/check-header.ts
@@ -24,9 +24,9 @@ import {
     configureExec,
     exec,
     filterFiles,
+    getChangesComparedToDefaultBranch,
     getChangesOfLastCommit,
     getLastModificationDate,
-    getUncommittedChanges,
     globby,
     readFile,
     replaceInFile,
@@ -59,8 +59,9 @@ export const CheckHeaderCommand = baseCommand() //
     .addOption(
         new Option(
             '-t, --type <type>',
-            'The scope of the check. In addition to a full recursive check, is also possible to only' +
-                ' consider pending changes or the last commit'
+            'The scope of the check. In addition to a full recursive check, it is also possible to only consider' +
+                ' the files changed compared to the default branch (`changes`, incl. uncommitted changes - i.e. the' +
+                ' files that would show up in a pull request) or the files changed with the last commit (`lastCommit`)'
         )
             .choices(checkTypes)
             .default('full')
@@ -111,7 +112,7 @@ async function getFiles(rootDir: string, options: HeaderCheckOptions): Promise<s
         return resolveFiles(result);
     }
 
-    let changedFiles = options.type === 'changes' ? getUncommittedChanges(rootDir) : getChangesOfLastCommit(rootDir);
+    let changedFiles = options.type === 'changes' ? getChangesComparedToDefaultBranch(rootDir) : getChangesOfLastCommit(rootDir);
     changedFiles = changedFiles.filter(minimatch.filter(includePattern));
 
     excludePattern.forEach(pattern => {
diff --git a/dev-packages/cli/src/commands/repo/common/utils.ts b/dev-packages/cli/src/commands/repo/common/utils.ts
index 844fc17..a374283 100644
--- a/dev-packages/cli/src/commands/repo/common/utils.ts
+++ b/dev-packages/cli/src/commands/repo/common/utils.ts
@@ -62,6 +62,23 @@ export function resolveWorkspaceDir(cliDir?: string): string {
     return process.cwd();
 }
 
+/**
+ * Resolves the absolute path to a specific repository within the workspace.
+ *
+ * Accepts a `--dir` that points at the workspace (the common case) as well as one that already
+ * points at the repository itself, so that callers passing `--dir <repo>` don't end up with the
+ * repository segment duplicated (e.g. `.../glsp-server-node/glsp-server-node`).
+ */
+export function resolveRepoDir(repo: GLSPRepo, cliDir?: string): string {
+    const workspaceDir = resolveWorkspaceDir(cliDir);
+    const repoDir = path.resolve(workspaceDir, repo);
+    // `--dir` already points at the repo itself: don't append the repo name a second time.
+    if (!fs.existsSync(repoDir) && path.basename(workspaceDir) === repo) {
+        return workspaceDir;
+    }
+    return repoDir;
+}
+
 // ── Repo discovery ────────────────────────────────────────────────────────
 
 export function discoverRepos(dir: string): GLSPRepo[] {
diff --git a/dev-packages/cli/src/commands/repo/server-node.ts b/dev-packages/cli/src/commands/repo/server-node.ts
index 6b0b272..435db40 100644
--- a/dev-packages/cli/src/commands/repo/server-node.ts
+++ b/dev-packages/cli/src/commands/repo/server-node.ts
@@ -18,7 +18,7 @@ import * as fs from 'fs';
 import * as path from 'path';
 import { Command } from 'commander';
 import { baseCommand } from '../../util';
-import { configureRepoEnv, resolveWorkspaceDir } from './common/utils';
+import { configureRepoEnv, resolveRepoDir } from './common/utils';
 
 export const BROWSER_BUNDLE_PATH = 'examples/workflow-server-bundled-web/wf-glsp-server-webworker.js';
 export const NODE_BUNDLE_PATH = 'examples/workflow-server-bundled/wf-glsp-server-node.js';
@@ -39,8 +39,7 @@ export const BrowserBundleCommand: Command = baseCommand()
     .action(async (_cmdOptions: unknown, thisCmd: Command) => {
         const cli = thisCmd.opts<{ dir?: string; verbose: boolean }>();
         configureRepoEnv(cli);
-        const dir = resolveWorkspaceDir(cli.dir);
-        const repoDir = path.resolve(dir, 'glsp-server-node');
+        const repoDir = resolveRepoDir('glsp-server-node', cli.dir);
         const bundlePath = resolveBundlePath(repoDir, BROWSER_BUNDLE_PATH, 'Browser bundle');
         process.stdout.write(bundlePath);
     });
@@ -53,8 +52,7 @@ export const NodeBundleCommand: Command = baseCommand()
     .action(async (_cmdOptions: unknown, thisCmd: Command) => {
         const cli = thisCmd.opts<{ dir?: string; verbose: boolean }>();
         configureRepoEnv(cli);
-        const dir = resolveWorkspaceDir(cli.dir);
-        const repoDir = path.resolve(dir, 'glsp-server-node');
+        const repoDir = resolveRepoDir('glsp-server-node', cli.dir);
         const bundlePath = resolveBundlePath(repoDir, NODE_BUNDLE_PATH, 'Node server bundle');
         process.stdout.write(bundlePath);
     });
diff --git a/dev-packages/cli/src/util/git-util.spec.ts b/dev-packages/cli/src/util/git-util.spec.ts
index ad5910f..a1b4334 100644
--- a/dev-packages/cli/src/util/git-util.spec.ts
+++ b/dev-packages/cli/src/util/git-util.spec.ts
@@ -15,9 +15,17 @@
  ********************************************************************************/
 
 import { expect } from 'chai';
-import { createSandbox } from 'sinon';
+import { createSandbox, match } from 'sinon';
 import * as processUtil from './process-util';
-import { commitChanges, getDefaultBranch, getLastModificationDate, getUncommittedChanges, hasChanges } from './git-util';
+import {
+    commitChanges,
+    getChangesComparedToDefaultBranch,
+    getDefaultBranch,
+    getDefaultBranchRef,
+    getLastModificationDate,
+    getUncommittedChanges,
+    hasChanges
+} from './git-util';
 
 const sandbox = createSandbox();
 
@@ -84,6 +92,44 @@ describe('git-util', () => {
         });
     });
 
+    describe('getDefaultBranchRef', () => {
+        it('should resolve the ref from origin/HEAD when available', () => {
+            execStub.withArgs(match(/symbolic-ref/)).returns('origin/develop');
+            expect(getDefaultBranchRef('/repo')).to.equal('origin/develop');
+        });
+
+        it('should fall back to the first existing candidate ref', () => {
+            execStub.withArgs(match(/symbolic-ref/)).returns('');
+            execStub.withArgs(match('origin/main')).throws(new Error('unknown revision'));
+            execStub.withArgs(match('origin/master')).throws(new Error('unknown revision'));
+            execStub.withArgs(match(/--verify --quiet main/)).returns('');
+            expect(getDefaultBranchRef('/repo')).to.equal('main');
+        });
+
+        it('should return undefined when no default branch can be determined', () => {
+            execStub.throws(new Error('not a git repository'));
+            expect(getDefaultBranchRef('/repo')).to.be.undefined;
+        });
+    });
+
+    describe('getChangesComparedToDefaultBranch', () => {
+        it('should merge committed and uncommitted changes and deduplicate', () => {
+            execStub.withArgs(match(/symbolic-ref/)).returns('origin/main');
+            execStub.withArgs(match(/diff --name-only/)).returns('src/a.ts\nsrc/b.ts');
+            execStub.withArgs(match(/status --porcelain/)).returns(' M src/b.ts\n?? src/c.ts');
+            const result = getChangesComparedToDefaultBranch('/repo');
+            expect(result).to.have.members(['/repo/src/a.ts', '/repo/src/b.ts', '/repo/src/c.ts']);
+            expect(result).to.have.length(3);
+        });
+
+        it('should only consider uncommitted changes when no default branch is found', () => {
+            execStub.throws(new Error('not a git repository'));
+            execStub.withArgs(match(/status --porcelain/)).returns(' M src/only.ts');
+            const result = getChangesComparedToDefaultBranch('/repo');
+            expect(result).to.deep.equal(['/repo/src/only.ts']);
+        });
+    });
+
     describe('getLastModificationDate', () => {
         it('should return a Date for a valid date string', () => {
             execStub.returns('2024-01-15 10:30:00 +0000');
diff --git a/dev-packages/cli/src/util/git-util.ts b/dev-packages/cli/src/util/git-util.ts
index 392541d..562cd79 100644
--- a/dev-packages/cli/src/util/git-util.ts
+++ b/dev-packages/cli/src/util/git-util.ts
@@ -67,6 +67,54 @@ export function getChangesOfLastCommit(path?: string): string[] {
         .map(file => resolve(path ?? process.cwd(), file));
 }
 
+/**
+ * Returns the files that have been changed compared to the default branch (e.g. master/main), i.e. the
+ * files that would show up as changed in a pull request. Includes both the committed changes of the
+ * current branch (relative to the merge-base with the default branch) and any uncommitted
+ * (staged, not staged or untracked) changes.
+ *
+ */
+export function getChangesComparedToDefaultBranch(path?: string): string[] {
+    const baseRef = getDefaultBranchRef(path);
+    const committedChanges = baseRef
+        ? exec(`git diff --name-only ${baseRef}...HEAD`, { cwd: path, silent: true })
+              .split('\n')
+              .filter(value => value.trim().length !== 0)
+              .map(file => resolve(path ?? process.cwd(), file.trim()))
+        : [];
+
+    return [...new Set([...committedChanges, ...getUncommittedChanges(path)])];
+}
+
+/**
+ * Resolves a git ref pointing to the tip of the default branch (e.g. master/main) that can be used for diffing.
+ * The lookup is performed offline and prefers the remote-tracking branch (origin/<default>) over the local branch.
+ * @returns The resolved ref or `undefined` if no default branch could be determined.
+ */
+export function getDefaultBranchRef(path?: string): string | undefined {
+    // `origin/HEAD` is set up by `git clone` and points to the remote default branch
+    try {
+        const ref = exec('git symbolic-ref --short refs/remotes/origin/HEAD', { cwd: path, silent: true, fatal: false });
+        if (ref) {
+            return ref;
+        }
+    } catch {
+        // not configured, fall through to the candidate lookup below
+    }
+
+    const candidates = ['origin/main', 'origin/master', 'main', 'master'];
+    return candidates.find(ref => refExists(ref, path));
+}
+
+function refExists(ref: string, path?: string): boolean {
+    try {
+        exec(`git rev-parse --verify --quiet ${ref}`, { cwd: path, silent: true, fatal: false });
+        return true;
+    } catch {
+        return false;
+    }
+}
+
 /**
  * Returns the commit message of the last commit
  *
diff --git a/dev-packages/cli/tests/e2e/check-header.e2e.spec.ts b/dev-packages/cli/tests/e2e/check-header.e2e.spec.ts
index 332348c..869ac82 100644
--- a/dev-packages/cli/tests/e2e/check-header.e2e.spec.ts
+++ b/dev-packages/cli/tests/e2e/check-header.e2e.spec.ts
@@ -90,6 +90,17 @@ describe('checkHeaders e2e', () => {
         expect(result.stdout).to.contain('1 copyright header violations');
     });
 
+    it('should check files changed against the default branch with --type changes', () => {
+        commitFile(repoDir, 'src/base.ts', VALID_HEADER + '\nconst x = 1;\n', 'add base file');
+        // Branch off and add a file without a header - only this file should be checked.
+        execSync('git checkout -b feature', { cwd: repoDir });
+        commitFile(repoDir, 'src/feature.ts', 'const y = 2;\n', 'add feature file');
+        const result = runCli(['checkHeaders', repoDir, '--type', 'changes']);
+        expect(result.stdout).to.contain('Check copy right headers of 1 files');
+        expect(result.stdout).to.contain('feature.ts');
+        expect(result.stdout).to.not.contain('base.ts');
+    });
+
     it('should only check last commit files with --type lastCommit', () => {
         commitFile(repoDir, 'src/old.ts', VALID_HEADER + '\nconst x = 1;\n', 'add old file');
         commitFile(repoDir, 'src/new.ts', 'const y = 2;\n', 'add new file');