test(server): cover tag-mode version pill; chore: rename gitArchive ref param; docs: prefix slash note

@@ -61,6 +61,7 @@   enabled: true
   package: "."              # or ./cmd/<name>
   source: bookmark          # opt in to bookmark-mode releases
   # bookmark_prefix: release/  # default; change only if you need a different prefix
+                               # must end in "/" so the version is its own path segment
 ```
 
 Register the release webhook (same command as tag mode; see [MANUAL.md](MANUAL.md) for webhook

@@ -166,17 +166,17 @@ 	}
 	return ver, nil
 }
 
-func gitArchive(bareRepo, prefix, tag, outPath string) error {
+func gitArchive(bareRepo, prefix, ref, outPath string) error {
 	out, err := os.Create(outPath)
 	if err != nil {
 		return err
 	}
 	defer out.Close()
-	cmd := exec.Command("git", "-C", bareRepo, "archive", "--format=tar.gz", "--prefix="+prefix+"/", tag)
+	cmd := exec.Command("git", "-C", bareRepo, "archive", "--format=tar.gz", "--prefix="+prefix+"/", ref)
 	cmd.Stdout = out
 	cmd.Stderr = os.Stderr
 	if err := cmd.Run(); err != nil {
-		return fmt.Errorf("git archive %s@%s: %w", bareRepo, tag, err)
+		return fmt.Errorf("git archive %s@%s: %w", bareRepo, ref, err)
 	}
 	return nil
 }

@@ -51,3 +51,29 @@ 	if ref.Message != "ship v1.2.3" {
 		t.Errorf("label = %q, want tip subject", ref.Message)
 	}
 }
+
+// tagRepo builds a bare "proj.git" in tag mode (no .custard.yaml) with a
+// lightweight semver tag v1.0.0 on a commit.
+func tagRepo(t *testing.T) *Server {
+	t.Helper()
+	root := t.TempDir()
+	work := filepath.Join(root, "work")
+	gitRun(t, root, "init", "-q", "-b", "main", "work")
+	if err := os.WriteFile(filepath.Join(work, "README.md"),
+		[]byte("hello\n"), 0o644); err != nil {
+		t.Fatal(err)
+	}
+	gitRun(t, work, "add", ".")
+	gitRun(t, work, "commit", "-q", "-m", "init")
+	gitRun(t, work, "tag", "v1.0.0")
+	gitRun(t, work, "clone", "-q", "--bare", work, filepath.Join(root, "proj.git"))
+	return &Server{store: gitread.New(root), cfg: config.Config{ReposPath: root}}
+}
+
+func TestLatestReleaseTagMode(t *testing.T) {
+	s := tagRepo(t)
+	ref, ok := s.latestRelease("proj")
+	if !ok || ref.Name != "v1.0.0" {
+		t.Fatalf("latestRelease = %q,%v; want v1.0.0,true", ref.Name, ok)
+	}
+}