diff --git a/cmd/vociferate/main_test.go b/cmd/vociferate/main_test.go
new file mode 100644
index 0000000..0139349
--- /dev/null
+++ b/cmd/vociferate/main_test.go
@@ -0,0 +1,120 @@
+package main
+
+import (
+	"flag"
+	"os"
+	"os/exec"
+	"path/filepath"
+	"strings"
+	"testing"
+)
+
+func TestMainRecommendPrintsTag(t *testing.T) {
+	root := t.TempDir()
+	writeFile(t, filepath.Join(root, "release-version"), "1.1.6\n")
+	writeFile(t, filepath.Join(root, "changelog.md"), "# Changelog\n\n## [Unreleased]\n\n### Added\n\n- Feature.\n\n## [1.1.6] - 2017-12-20\n")
+
+	stdout, stderr, code := runMain(t, "--recommend", "--root", root)
+	if code != 0 {
+		t.Fatalf("expected exit 0, got %d (stderr: %s)", code, stderr)
+	}
+	if strings.TrimSpace(stdout) != "v1.2.0" {
+		t.Fatalf("unexpected recommended tag: %q", strings.TrimSpace(stdout))
+	}
+}
+
+func TestMainUsageExitWhenRequiredFlagsMissing(t *testing.T) {
+	_, stderr, code := runMain(t)
+	if code != 2 {
+		t.Fatalf("expected exit 2, got %d", code)
+	}
+	if !strings.Contains(stderr, "usage: vociferate") {
+		t.Fatalf("expected usage text in stderr, got: %s", stderr)
+	}
+}
+
+func TestMainPrepareUpdatesFiles(t *testing.T) {
+	root := t.TempDir()
+	writeFile(t, filepath.Join(root, ".git", "config"), "[remote \"origin\"]\n\turl = git@git.hrafn.xyz:aether/vociferate.git\n")
+	writeFile(t, filepath.Join(root, "release-version"), "1.1.6\n")
+	writeFile(t, filepath.Join(root, "changelog.md"), "# Changelog\n\n## [Unreleased]\n\n### Fixed\n\n- Patch note.\n\n## [1.1.6] - 2017-12-20\n")
+
+	_, stderr, code := runMain(t, "--version", "v1.1.7", "--date", "2026-03-20", "--root", root)
+	if code != 0 {
+		t.Fatalf("expected exit 0, got %d (stderr: %s)", code, stderr)
+	}
+
+	versionBytes, err := os.ReadFile(filepath.Join(root, "release-version"))
+	if err != nil {
+		t.Fatalf("read release-version: %v", err)
+	}
+	if strings.TrimSpace(string(versionBytes)) != "1.1.7" {
+		t.Fatalf("unexpected version file value: %q", string(versionBytes))
+	}
+}
+
+func TestMainPrepareReturnsExitOneOnFailure(t *testing.T) {
+	root := t.TempDir()
+	_, stderr, code := runMain(t, "--version", "v1.1.7", "--date", "2026-03-20", "--root", root)
+	if code != 1 {
+		t.Fatalf("expected exit 1, got %d", code)
+	}
+	if !strings.Contains(stderr, "prepare release") {
+		t.Fatalf("expected prepare error in stderr, got: %s", stderr)
+	}
+}
+
+func TestHelperProcess(t *testing.T) {
+	if os.Getenv("GO_WANT_HELPER_PROCESS") != "1" {
+		return
+	}
+
+	idx := -1
+	for i, arg := range os.Args {
+		if arg == "--" {
+			idx = i
+			break
+		}
+	}
+	if idx == -1 {
+		os.Exit(2)
+	}
+
+	args := append([]string{"vociferate"}, os.Args[idx+1:]...)
+	os.Args = args
+	flag.CommandLine = flag.NewFlagSet(args[0], flag.ExitOnError)
+
+	main()
+	os.Exit(0)
+}
+
+func runMain(t *testing.T, args ...string) (string, string, int) {
+	t.Helper()
+
+	cmdArgs := append([]string{"-test.run=TestHelperProcess", "--"}, args...)
+	cmd := exec.Command(os.Args[0], cmdArgs...)
+	cmd.Env = append(os.Environ(), "GO_WANT_HELPER_PROCESS=1")
+
+	out, err := cmd.CombinedOutput()
+	output := string(out)
+	if err == nil {
+		return output, "", 0
+	}
+
+	if exitErr, ok := err.(*exec.ExitError); ok {
+		return "", output, exitErr.ExitCode()
+	}
+
+	t.Fatalf("run helper process: %v", err)
+	return "", "", -1
+}
+
+func writeFile(t *testing.T, path, content string) {
+	t.Helper()
+	if err := os.MkdirAll(filepath.Dir(path), 0o755); err != nil {
+		t.Fatalf("mkdir for %s: %v", path, err)
+	}
+	if err := os.WriteFile(path, []byte(content), 0o644); err != nil {
+		t.Fatalf("write file %s: %v", path, err)
+	}
+}
diff --git a/internal/vociferate/vociferate_internal_test.go b/internal/vociferate/vociferate_internal_test.go
new file mode 100644
index 0000000..c7df7de
--- /dev/null
+++ b/internal/vociferate/vociferate_internal_test.go
@@ -0,0 +1,123 @@
+package vociferate
+
+import (
+	"os"
+	"path/filepath"
+	"testing"
+)
+
+func TestNormalizeRepoURL(t *testing.T) {
+	t.Parallel()
+
+	tests := []struct {
+		name      string
+		remoteURL string
+		wantURL   string
+		wantOK    bool
+	}{
+		{name: "https", remoteURL: "https://git.hrafn.xyz/aether/vociferate.git", wantURL: "https://git.hrafn.xyz/aether/vociferate", wantOK: true},
+		{name: "http", remoteURL: "http://teapot:3000/aether/vociferate.git", wantURL: "http://teapot:3000/aether/vociferate", wantOK: true},
+		{name: "ssh with scheme", remoteURL: "ssh://git@git.hrafn.xyz/aether/vociferate.git", wantURL: "https://git.hrafn.xyz/aether/vociferate", wantOK: true},
+		{name: "scp style", remoteURL: "git@git.hrafn.xyz:aether/vociferate.git", wantURL: "https://git.hrafn.xyz/aether/vociferate", wantOK: true},
+		{name: "empty", remoteURL: "", wantURL: "", wantOK: false},
+		{name: "unsupported scheme", remoteURL: "ftp://example.com/repo.git", wantURL: "", wantOK: false},
+		{name: "invalid ssh missing user", remoteURL: "ssh://git.hrafn.xyz/aether/vociferate.git", wantURL: "", wantOK: false},
+		{name: "invalid scp style", remoteURL: "git.hrafn.xyz:aether/vociferate.git", wantURL: "", wantOK: false},
+	}
+
+	for _, tt := range tests {
+		tt := tt
+		t.Run(tt.name, func(t *testing.T) {
+			t.Parallel()
+			gotURL, gotOK := normalizeRepoURL(tt.remoteURL)
+			if gotOK != tt.wantOK {
+				t.Fatalf("normalizeRepoURL(%q) ok = %v, want %v", tt.remoteURL, gotOK, tt.wantOK)
+			}
+			if gotURL != tt.wantURL {
+				t.Fatalf("normalizeRepoURL(%q) url = %q, want %q", tt.remoteURL, gotURL, tt.wantURL)
+			}
+		})
+	}
+}
+
+func TestParseSemver(t *testing.T) {
+	t.Parallel()
+
+	tests := []struct {
+		name    string
+		input   string
+		want    semver
+		wantErr bool
+	}{
+		{name: "valid", input: "1.2.3", want: semver{major: 1, minor: 2, patch: 3}, wantErr: false},
+		{name: "missing part", input: "1.2", wantErr: true},
+		{name: "non numeric", input: "1.two.3", wantErr: true},
+	}
+
+	for _, tt := range tests {
+		tt := tt
+		t.Run(tt.name, func(t *testing.T) {
+			t.Parallel()
+			got, err := parseSemver(tt.input)
+			if tt.wantErr {
+				if err == nil {
+					t.Fatalf("parseSemver(%q) expected error", tt.input)
+				}
+				return
+			}
+			if err != nil {
+				t.Fatalf("parseSemver(%q) unexpected error: %v", tt.input, err)
+			}
+			if got != tt.want {
+				t.Fatalf("parseSemver(%q) = %+v, want %+v", tt.input, got, tt.want)
+			}
+		})
+	}
+}
+
+func TestOriginRemoteURLFromGitConfig(t *testing.T) {
+	t.Parallel()
+
+	t.Run("origin exists", func(t *testing.T) {
+		t.Parallel()
+		config := "[core]\n\trepositoryformatversion = 0\n[remote \"origin\"]\n\turl = git@git.hrafn.xyz:aether/vociferate.git\n"
+		url, ok := originRemoteURLFromGitConfig(config)
+		if !ok {
+			t.Fatal("expected origin url to be found")
+		}
+		if url != "git@git.hrafn.xyz:aether/vociferate.git" {
+			t.Fatalf("unexpected url: %q", url)
+		}
+	})
+
+	t.Run("origin missing", func(t *testing.T) {
+		t.Parallel()
+		config := "[core]\n\trepositoryformatversion = 0\n[remote \"upstream\"]\n\turl = git@git.hrafn.xyz:aether/vociferate.git\n"
+		_, ok := originRemoteURLFromGitConfig(config)
+		if ok {
+			t.Fatal("expected origin url to be absent")
+		}
+	})
+}
+
+func TestDeriveRepositoryURLFromGitConfigFallback(t *testing.T) {
+	t.Setenv("GITHUB_SERVER_URL", "")
+	t.Setenv("GITHUB_REPOSITORY", "")
+
+	root := t.TempDir()
+	configPath := filepath.Join(root, ".git", "config")
+	if err := os.MkdirAll(filepath.Dir(configPath), 0o755); err != nil {
+		t.Fatalf("mkdir .git: %v", err)
+	}
+	if err := os.WriteFile(configPath, []byte("[remote \"origin\"]\n\turl = git@git.hrafn.xyz:aether/vociferate.git\n"), 0o644); err != nil {
+		t.Fatalf("write git config: %v", err)
+	}
+
+	url, ok := deriveRepositoryURL(root)
+	if !ok {
+		t.Fatal("expected repository URL from git config")
+	}
+	if url != "https://git.hrafn.xyz/aether/vociferate" {
+		t.Fatalf("unexpected repository URL: %q", url)
+	}
+}