memory-service: Skill for Claude Code

GORM Query Patterns

Use this skill when touching GORM-backed persistence code in this repo.

Base the query shape on whether "no row" is expected control flow or an exceptional condition.

Rules

• For slice reads, use Find(&rows). An empty result set is normal.
• For a single-row lookup where "not found" is expected, use Limit(1).Find(&row) and branch on RowsAffected.
• Do not use Find(&row) without Limit(1) for a single struct destination. GORM's query docs warn that it can read more than one row and is not deterministic without a limit.
• Use Take, First, or Last only when you want GORM to return ErrRecordNotFound.
• Use First or Last only when the ordering is part of the behavior. Otherwise prefer Take for required single-row fetches.
• When the store API returns a domain-level ErrNotFound or nil, nil for absence, do not route that control flow through gorm.ErrRecordNotFound; check RowsAffected instead.

Preferred Patterns

Expected absence, returning a domain ErrNotFound:

var row SomeRecord
result := tx.Where("user_id = ? AND external_id = ?", companyID, externalID).
	Limit(1).
	Find(&row)
if result.Error != nil {
	return nil, result.Error
}
if result.RowsAffected == 0 {
	return nil, ErrNotFound
}
return &row, nil

Expected absence, returning no result:

var row SomeRecord
result := tx.Where("user_id = ? AND status = ?", companyID, "running").
	Order("started_at desc").
	Limit(1).
	Find(&row)
if result.Error != nil {
	return nil, result.Error
}
if result.RowsAffected == 0 {
	return nil, nil
}
return &row, nil

Required row, missing row is exceptional:

var row SomeRecord
if err := tx.Where("id = ? AND user_id = ?", id, companyID).Take(&row).Error; err != nil {
	if errors.Is(err, gorm.ErrRecordNotFound) {
		return ErrNotFound
	}
	return err
}

Repo Notes

• GORM stores live in internal/plugin/store/postgres and internal/plugin/store/sqlite. Inside route-scoped transactions, get the handle with dbFor(ctx) / writeDBFor(ctx, ...), not s.db.
• Example of the optional single-row pattern: internal/plugin/store/postgres/episodic_kind.go (Limit(1).Find(...) plus RowsAffected).
• Prefer consistent query shapes within one file. If a helper uses the optional-single-row pattern, keep nearby helpers aligned.