feat(infra): implement zero-dependency pure in-memory cache plugin

backend/plugins/infra/cache_memory/plugin.go

@@ -0,0 +1,66 @@
+// Copyright 2026 Arctel.net
+// SPDX-License-Identifier: Apache-2.0
+
+// Package cache_memory provides the in-memory cache infrastructure plugin for Cordis.
+package cache_memory
+
+import (
+	"Wavelet/core"
+	"Wavelet/core/contracts"
+)
+
+const defaultRAMCapacity = 10000
+
+// Option configures the cache_memory plugin.
+type Option func(*Plugin)
+
+// WithCapacity sets the maximum capacity for the in-memory cache.
+func WithCapacity(capacity int) Option {
+	return func(p *Plugin) {
+		p.capacity = capacity
+	}
+}
+
+// Plugin implements core.Plugin to provide contracts.CacheService using in-memory storage.
+type Plugin struct {
+	capacity int
+}
+
+// New creates a new in-memory cache infrastructure plugin.
+func New(opts ...Option) *Plugin {
+	p := &Plugin{
+		capacity: defaultRAMCapacity,
+	}
+	for _, opt := range opts {
+		if opt != nil {
+			opt(p)
+		}
+	}
+	return p
+}
+
+// Name returns the unique identifier of the cache_memory plugin.
+func (p *Plugin) Name() string {
+	return "cache_memory"
+}
+
+// Manifest returns the plugin metadata.
+func (p *Plugin) Manifest() core.Manifest {
+	return core.Manifest{
+		Name:        "cache_memory",
+		Version:     "1.0.0",
+		Description: "Zero-dependency pure in-memory cache infrastructure plugin",
+		Author:      "Wavelet Team",
+	}
+}
+
+// Apply mounts the in-memory cache service into the Context.
+func (p *Plugin) Apply(ctx *core.Context) error {
+	svc, err := newMemoryCacheService(p.capacity, ctx.Events())
+	if err != nil {
+		return err
+	}
+
+	core.Provide[contracts.CacheService](ctx, svc)
+	return nil
+}