Agent-System-Backend/internal/store/system_identity.go

package store

import (
	"database/sql"
	"errors"
	"fmt"
)

// ErrSystemIdentityMismatch 库内身份与期望不符（错库/错实例/多行）——启动必须失败。
var ErrSystemIdentityMismatch = errors.New("system identity mismatch")

// ErrSystemIdentityMissing 表中无身份行——须先 Ensure（svc init / 首次建立），禁止静默插入。
var ErrSystemIdentityMissing = errors.New("system identity missing")

// SystemIdentity 是 agent_system_identity 表的一行（一库一服务身份）。
type SystemIdentity struct {
	InstanceID    string
	DBRef         string
	SchemaVersion int
	CreatedAt     string
}

// EnsureSystemIdentity 仅用于显式建立路径：表空则插入；已存在且一致则幂等；
// 不一致或多余行 fail-closed。绝不在常规 start 路径调用以「补写」掩盖漂移。
func (s *Store) EnsureSystemIdentity(instanceID, dbref string) error {
	if instanceID == "" {
		return fmt.Errorf("EnsureSystemIdentity: instance_id 为空")
	}
	if dbref == "" {
		dbref = "sqlite"
	}
	row, n, err := s.readSystemIdentity()
	if err != nil {
		return err
	}
	if n > 1 {
		return fmt.Errorf("%w: agent_system_identity 有 %d 行（期望至多 1）", ErrSystemIdentityMismatch, n)
	}
	if n == 1 {
		if row.InstanceID != instanceID || row.DBRef != dbref {
			return fmt.Errorf("%w: 库内 instance_id=%q dbref=%q ≠ 期望 %q / %q",
				ErrSystemIdentityMismatch, row.InstanceID, row.DBRef, instanceID, dbref)
		}
		return nil
	}
	ver := latestMigrationVersion()
	_, err = s.db.Exec(s.q(`INSERT INTO agent_system_identity(instance_id, dbref, schema_version, created_at) VALUES(?,?,?,?)`),
		instanceID, dbref, ver, nowISO())
	if err != nil {
		return fmt.Errorf("EnsureSystemIdentity insert: %w", err)
	}
	return nil
}

// VerifySystemIdentity 常规启动校验：必须恰有一行且与期望一致；缺失不插入。
func (s *Store) VerifySystemIdentity(instanceID, dbref string) error {
	if instanceID == "" {
		return fmt.Errorf("VerifySystemIdentity: instance_id 为空")
	}
	if dbref == "" {
		dbref = "sqlite"
	}
	row, n, err := s.readSystemIdentity()
	if err != nil {
		return err
	}
	if n == 0 {
		return fmt.Errorf("%w: agent_system_identity 无行（先 svc init / identity ensure，禁止静默建空身份）", ErrSystemIdentityMissing)
	}
	if n > 1 {
		return fmt.Errorf("%w: agent_system_identity 有 %d 行（期望至多 1）", ErrSystemIdentityMismatch, n)
	}
	if row.InstanceID != instanceID || row.DBRef != dbref {
		return fmt.Errorf("%w: 库内 instance_id=%q dbref=%q ≠ 期望 %q / %q",
			ErrSystemIdentityMismatch, row.InstanceID, row.DBRef, instanceID, dbref)
	}
	return nil
}

func (s *Store) readSystemIdentity() (SystemIdentity, int, error) {
	rows, err := s.db.Query(`SELECT instance_id, dbref, schema_version, created_at FROM agent_system_identity`)
	if err != nil {
		return SystemIdentity{}, 0, fmt.Errorf("read agent_system_identity: %w", err)
	}
	defer rows.Close()
	var out SystemIdentity
	n := 0
	for rows.Next() {
		n++
		var id, ref, created string
		var ver int
		if err := rows.Scan(&id, &ref, &ver, &created); err != nil {
			return SystemIdentity{}, 0, err
		}
		if n == 1 {
			out = SystemIdentity{InstanceID: id, DBRef: ref, SchemaVersion: ver, CreatedAt: created}
		}
	}
	if err := rows.Err(); err != nil {
		return SystemIdentity{}, 0, err
	}
	return out, n, nil
}

// GetSystemIdentity 读取唯一身份行（无行返回 sql.ErrNoRows）。
func (s *Store) GetSystemIdentity() (SystemIdentity, error) {
	row, n, err := s.readSystemIdentity()
	if err != nil {
		return SystemIdentity{}, err
	}
	if n == 0 {
		return SystemIdentity{}, sql.ErrNoRows
	}
	if n > 1 {
		return SystemIdentity{}, fmt.Errorf("%w: %d rows", ErrSystemIdentityMismatch, n)
	}
	return row, nil
}