go-store/CLAUDE.md

CLAUDE.md

This file provides guidance to Claude Code (claude.ai/code) when working with code in this repository.

What This Is

SQLite key-value store with TTL, namespace isolation, and reactive events. Pure Go (no CGO). Module: dappco.re/go/core/store

AX Notes

• Prefer descriptive names over abbreviations.
• Public comments should show real usage with concrete values.
• Keep examples in UK English.
• Do not add compatibility aliases; the primary API names are the contract.
• Preserve the single-connection SQLite design.
• Verify with go test ./..., go test -race ./..., and go vet ./... before committing.
• Use conventional commits and include the Co-Authored-By: Virgil <virgil@lethean.io> trailer.

Getting Started

Part of the Go workspace at ~/Code/go.work—run go work sync after cloning. Single Go package with store.go (core), events.go (watchers/callbacks), and scope.go (scoping/quota).

go test ./... -count=1

Commands

go test ./...                        # Run all tests
go test -v -run TestEvents_Watch_Good_SpecificKey ./... # Run single test
go test -race ./...                  # Race detector (must pass before commit)
go test -cover ./...                 # Coverage (target: 95%+)
go test -bench=. -benchmem ./...     # Benchmarks
golangci-lint run ./...              # Lint (config in .golangci.yml)
go vet ./...                         # Vet

Architecture

Single-connection SQLite. store.go pins MaxOpenConns(1) because SQLite pragmas (WAL, busy_timeout) are per-connection — a pool would hand out unpragma'd connections causing SQLITE_BUSY. This is the most important architectural decision; don't change it.

Three-layer design:

• store.go — Core Store type: CRUD on an entries table keyed by (group_name, entry_key), TTL via expires_at (Unix ms), background purge goroutine (60s interval), text/template rendering, iter.Seq2 iterators
• events.go — Event system: Watch/Unwatch (buffered chan, cap 16, non-blocking sends drop events) and OnChange callbacks (synchronous in writer goroutine). Watcher and callback registries use separate locks, so callbacks can register or unregister subscriptions without deadlocking.
• scope.go — ScopedStore wraps *Store, prefixes groups with namespace:. Quota enforcement (MaxKeys/MaxGroups) checked before writes; upserts bypass quota. Namespace regex: ^[a-zA-Z0-9-]+$

TTL enforcement is triple-layered: lazy delete on Get, query-time WHERE filtering on bulk reads, and background purge goroutine.

LIKE queries use escapeLike() with ^ as escape char to prevent SQL wildcard injection in CountAll and Groups/GroupsSeq.

Key API

package main

import (
	"fmt"
	"time"

	"dappco.re/go/core/store"
)

func main() {
	storeInstance, err := store.New(":memory:")
	if err != nil {
		return
	}
	defer storeInstance.Close()

	if err := storeInstance.Set("group", "key", "value"); err != nil {
		return
	}
	value, err := storeInstance.Get("group", "key")
	if err != nil {
		return
	}
	fmt.Println(value)

	if err := storeInstance.SetWithTTL("session", "token", "abc123", 5*time.Minute); err != nil {
		return
	}

	scopedStore, err := store.NewScoped(storeInstance, "tenant")
	if err != nil {
		return
	}
	if err := scopedStore.SetIn("config", "theme", "dark"); err != nil {
		return
	}

	quotaScopedStore, err := store.NewScopedWithQuota(storeInstance, "tenant", store.QuotaConfig{MaxKeys: 100, MaxGroups: 10})
	if err != nil {
		return
	}
	if err := quotaScopedStore.SetIn("prefs", "locale", "en-GB"); err != nil {
		return
	}

	events := storeInstance.Watch("group")
	defer storeInstance.Unwatch("group", events)
	go func() {
		for event := range events {
			fmt.Println(event.Type, event.Group, event.Key, event.Value)
		}
	}()

	unregister := storeInstance.OnChange(func(event store.Event) {
		fmt.Println("changed", event.Group, event.Key, event.Value)
	})
	defer unregister()
}

Coding Standards

• UK English in all code, comments, docs (colour, behaviour, serialise, organisation)
• Error strings: "store.Method: what failed" — self-identifying without stack traces
• go test -race ./... must pass before commit
• Conventional commits: type(scope): description
• Co-Author: Co-Authored-By: Virgil <virgil@lethean.io>
• Only runtime dependency allowed: modernc.org/sqlite. No CGO. New deps must be pure Go with EUPL-1.2-compatible licence.

Test Conventions

• Test names follow Test<File>_<Function>_<Good|Bad|Ugly>, for example TestEvents_Watch_Good_SpecificKey
• Use New(":memory:") unless testing persistence; use t.TempDir() for file-backed
• TTL tests: 1ms TTL + 5ms sleep; use sync.WaitGroup not sleeps for goroutine sync
• require for preconditions, assert for verifications (testify)

Adding a New Method

1. Implement on *Store in store.go
2. If mutating, call storeInstance.notify(Event{...}) after successful database write
3. Add delegation method on ScopedStore in scope.go (prefix the group)
4. Update checkQuota in scope.go if it affects key/group counts
5. Write Test<File>_<Function>_<Good|Bad|Ugly> tests
6. Run go test -race ./... and go vet ./...

Docs

• docs/architecture.md — full internal design details
• docs/development.md — test patterns, benchmarks, coding standards
• docs/history.md — completed phases, known limitations