feat: 实现 SQLite 迁移备份、完整表结构与简单写入队列

internal/store/migrate.go

@@ -5,6 +5,8 @@ import (
 	"embed"
 	"fmt"
 	"io/fs"
+	"os"
+	"path/filepath"
 	"sort"
 	"strconv"
 	"strings"
@@ -14,8 +16,11 @@ import (
 //go:embed migrations/*.sql
 var migrationFS embed.FS
 
-// Migrate 应用尚未执行的迁移。T0.1 仅为空执行器加 0001 占位；完整备份与表结构见 T0.3。
-func Migrate(db *sql.DB) error {
+// Migrate 应用尚未执行的嵌入迁移。
+// 若 dbExisted 为 true（调用 Open/Migrate 前已有 nixmsg.db）且存在未应用版本，
+// 先 VACUUM INTO <data_dir>/backup/pre-migrate-<时间>.db，再迁移。
+// 任一版本失败则返回错误，调用方不得继续带半新半旧库提供服务。
+func Migrate(db *sql.DB, dataDir string, dbExisted bool) error {
 	if _, err := db.Exec(`
 CREATE TABLE IF NOT EXISTS schema_migrations (
   version INTEGER PRIMARY KEY,
@@ -24,9 +29,38 @@ CREATE TABLE IF NOT EXISTS schema_migrations (
 		return fmt.Errorf("ensure schema_migrations: %w", err)
 	}
 
+	pending, err := pendingMigrations(db)
+	if err != nil {
+		return err
+	}
+	if len(pending) == 0 {
+		return nil
+	}
+
+	if dbExisted {
+		if err := backupBeforeMigrate(db, dataDir); err != nil {
+			return err
+		}
+	}
+
+	for _, m := range pending {
+		if err := applyMigration(db, m); err != nil {
+			return err
+		}
+	}
+	return nil
+}
+
+type migrationFile struct {
+	version int
+	name    string
+	body    string
+}
+
+func pendingMigrations(db *sql.DB) ([]migrationFile, error) {
 	entries, err := fs.ReadDir(migrationFS, "migrations")
 	if err != nil {
-		return fmt.Errorf("read migrations: %w", err)
+		return nil, fmt.Errorf("read migrations: %w", err)
 	}
 	var names []string
 	for _, e := range entries {
@@ -37,10 +71,11 @@ CREATE TABLE IF NOT EXISTS schema_migrations (
 	}
 	sort.Strings(names)
 
+	var pending []migrationFile
 	for _, name := range names {
 		version, err := parseMigrationVersion(name)
 		if err != nil {
-			return err
+			return nil, err
 		}
 		var exists int
 		err = db.QueryRow(`SELECT 1 FROM schema_migrations WHERE version = ?`, version).Scan(&exists)
@@ -48,36 +83,58 @@ CREATE TABLE IF NOT EXISTS schema_migrations (
 			continue
 		}
 		if err != sql.ErrNoRows {
-			return fmt.Errorf("check migration %d: %w", version, err)
+			return nil, fmt.Errorf("check migration %d: %w", version, err)
 		}
-
 		body, err := migrationFS.ReadFile("migrations/" + name)
 		if err != nil {
-			return fmt.Errorf("read migration %s: %w", name, err)
+			return nil, fmt.Errorf("read migration %s: %w", name, err)
 		}
-		sqlText := strings.TrimSpace(string(body))
-		tx, err := db.Begin()
-		if err != nil {
-			return fmt.Errorf("begin migration %d: %w", version, err)
-		}
-		if sqlText != "" {
-			if _, err := tx.Exec(sqlText); err != nil {
-				_ = tx.Rollback()
-				return fmt.Errorf("apply migration %d: %w", version, err)
-			}
-		}
-		if _, err := tx.Exec(
-			`INSERT INTO schema_migrations(version, applied_at) VALUES(?, ?)`,
-			version,
-			time.Now().UnixMilli(),
-		); err != nil {
+		pending = append(pending, migrationFile{
+			version: version,
+			name:    name,
+			body:    strings.TrimSpace(string(body)),
+		})
+	}
+	return pending, nil
+}
+
+func backupBeforeMigrate(db *sql.DB, dataDir string) error {
+	backupDir := filepath.Join(dataDir, "backup")
+	if err := os.MkdirAll(backupDir, 0o755); err != nil {
+		return fmt.Errorf("mkdir backup: %w", err)
+	}
+	stamp := time.Now().UTC().Format("20060102T150405")
+	backupPath := filepath.Join(backupDir, "pre-migrate-"+stamp+".db")
+	// SQLite VACUUM INTO 需要字面量路径；统一用斜杠，并对单引号转义。
+	quoted := strings.ReplaceAll(filepath.ToSlash(backupPath), "'", "''")
+	if _, err := db.Exec("VACUUM INTO '" + quoted + "'"); err != nil {
+		return fmt.Errorf("vacuum into backup %s: %w", backupPath, err)
+	}
+	return nil
+}
+
+func applyMigration(db *sql.DB, m migrationFile) error {
+	tx, err := db.Begin()
+	if err != nil {
+		return fmt.Errorf("begin migration %d: %w", m.version, err)
+	}
+	if m.body != "" {
+		if _, err := tx.Exec(m.body); err != nil {
 			_ = tx.Rollback()
-			return fmt.Errorf("record migration %d: %w", version, err)
-		}
-		if err := tx.Commit(); err != nil {
-			return fmt.Errorf("commit migration %d: %w", version, err)
+			return fmt.Errorf("apply migration %d (%s): %w", m.version, m.name, err)
 		}
 	}
+	if _, err := tx.Exec(
+		`INSERT INTO schema_migrations(version, applied_at) VALUES(?, ?)`,
+		m.version,
+		time.Now().UnixMilli(),
+	); err != nil {
+		_ = tx.Rollback()
+		return fmt.Errorf("record migration %d: %w", m.version, err)
+	}
+	if err := tx.Commit(); err != nil {
+		return fmt.Errorf("commit migration %d: %w", m.version, err)
+	}
 	return nil
 }