feat: add native Windows hierarchy test harness

internal/client/spool/spool.go

@@ -11,6 +11,7 @@ import (
 	"net/url"
 	"path/filepath"
 	"strconv"
+	"strings"
 	"sync"
 	"time"
 
@@ -116,8 +117,7 @@ func Open(ctx context.Context, options Options) (*Store, error) {
 	query.Add("_pragma", "foreign_keys(ON)")
 	query.Add("_pragma", "synchronous(FULL)")
 	query.Add("_pragma", "busy_timeout("+strconv.FormatInt(options.BusyTimeout.Milliseconds(), 10)+")")
-	databaseURL := &url.URL{Scheme: "file", Path: filepath.ToSlash(databasePath), RawQuery: query.Encode()}
-	db, err := sql.Open("sqlite", databaseURL.String())
+	db, err := sql.Open("sqlite", sqliteFileURI(databasePath, query))
 	if err != nil {
 		_ = unlock()
 		return nil, err
@@ -136,6 +136,17 @@ func Open(ctx context.Context, options Options) (*Store, error) {
 	return store, nil
 }
 
+// sqliteFileURI creates a file: URI with no authority. SQLite requires a
+// Windows drive path to be /C:/... in the URI path; without the leading slash
+// net/url renders C: as an authority (file://C:/...), which SQLite rejects.
+func sqliteFileURI(path string, query url.Values) string {
+	path = strings.ReplaceAll(path, `\`, "/")
+	if len(path) >= 2 && path[1] == ':' {
+		path = "/" + path
+	}
+	return (&url.URL{Scheme: "file", Path: path, RawQuery: query.Encode()}).String()
+}
+
 func (store *Store) ClientInstanceID() domain.UUID { return store.identity }
 
 func (store *Store) Close() error {