diff --git a/internal/homesick/core/commit_test.go b/internal/homesick/core/commit_test.go
new file mode 100644
index 0000000..20064e5
--- /dev/null
+++ b/internal/homesick/core/commit_test.go
@@ -0,0 +1,112 @@
+package core_test
+
+import (
+	"io"
+	"os"
+	"os/exec"
+	"path/filepath"
+	"strings"
+	"testing"
+	"time"
+
+	"git.hrafn.xyz/aether/gosick/internal/homesick/core"
+	git "github.com/go-git/go-git/v5"
+	"github.com/go-git/go-git/v5/plumbing/object"
+	"github.com/stretchr/testify/require"
+	"github.com/stretchr/testify/suite"
+)
+
+type CommitSuite struct {
+	suite.Suite
+	tmpDir   string
+	homeDir  string
+	reposDir string
+	app      *core.App
+}
+
+func TestCommitSuite(t *testing.T) {
+	suite.Run(t, new(CommitSuite))
+}
+
+func (s *CommitSuite) SetupTest() {
+	s.tmpDir = s.T().TempDir()
+	s.homeDir = filepath.Join(s.tmpDir, "home")
+	s.reposDir = filepath.Join(s.homeDir, ".homesick", "repos")
+	require.NoError(s.T(), os.MkdirAll(s.reposDir, 0o755))
+
+	s.app = &core.App{
+		HomeDir:  s.homeDir,
+		ReposDir: s.reposDir,
+		Stdout:   io.Discard,
+		Stderr:   io.Discard,
+	}
+}
+
+func (s *CommitSuite) createCastleRepo(castle string) string {
+	castleRoot := filepath.Join(s.reposDir, castle)
+	repo, err := git.PlainInit(castleRoot, false)
+	require.NoError(s.T(), err)
+
+	filePath := filepath.Join(castleRoot, "home", ".vimrc")
+	require.NoError(s.T(), os.MkdirAll(filepath.Dir(filePath), 0o755))
+	require.NoError(s.T(), os.WriteFile(filePath, []byte("set number\n"), 0o644))
+
+	wt, err := repo.Worktree()
+	require.NoError(s.T(), err)
+	_, err = wt.Add("home/.vimrc")
+	require.NoError(s.T(), err)
+	_, err = wt.Commit("initial", &git.CommitOptions{Author: &object.Signature{
+		Name:  "Commit Test",
+		Email: "commit@test.local",
+		When:  time.Now(),
+	}})
+	require.NoError(s.T(), err)
+
+	return castleRoot
+}
+
+func gitOutputAt(dir string, args ...string) (string, error) {
+	cmd := exec.Command("git", args...)
+	cmd.Dir = dir
+	out, err := cmd.Output()
+	if err != nil {
+		return "", err
+	}
+	return string(out), nil
+}
+
+func (s *CommitSuite) TestCommit_CreatesCommitWithMessage() {
+	castleRoot := s.createCastleRepo("dotfiles")
+	target := filepath.Join(castleRoot, "home", ".vimrc")
+	require.NoError(s.T(), os.WriteFile(target, []byte("set number\nsyntax on\n"), 0o644))
+
+	require.NoError(s.T(), s.app.Commit("dotfiles", "update vimrc"))
+
+	subject, err := gitOutputAt(castleRoot, "log", "-1", "--pretty=%s")
+	require.NoError(s.T(), err)
+	require.Equal(s.T(), "update vimrc\n", subject)
+}
+
+func (s *CommitSuite) TestCommit_MessageEscaping() {
+	castleRoot := s.createCastleRepo("dotfiles")
+	target := filepath.Join(castleRoot, "home", ".vimrc")
+	require.NoError(s.T(), os.WriteFile(target, []byte("set number\nset relativenumber\n"), 0o644))
+
+	msg := "fix \"quoted\" message: keep spaces"
+	require.NoError(s.T(), s.app.Commit("dotfiles", msg))
+
+	subject, err := gitOutputAt(castleRoot, "log", "-1", "--pretty=%s")
+	require.NoError(s.T(), err)
+	require.Equal(s.T(), msg+"\n", subject)
+}
+
+func (s *CommitSuite) TestCommit_RequiresMessage() {
+	err := s.app.Commit("dotfiles", "   ")
+	require.Error(s.T(), err)
+	require.Contains(s.T(), strings.ToLower(err.Error()), "message")
+}
+
+func (s *CommitSuite) TestCommit_MissingCastleReturnsError() {
+	err := s.app.Commit("missing", "msg")
+	require.Error(s.T(), err)
+}