feat: add menus, subscriptions, public users, and plugin bridge to SDK

New capability interfaces:
- menus.Menus: menu/nav access (GetMenuByName, GetMenuItems)
- subscriptions.Subscriptions: tier/plan access (GetUserTierLevel, GetTierBySlug, ListActivePlans)
- auth.PublicUsers: public user profiles (GetByUsername, GetByID)
- plugin.PluginBridge: inter-plugin service registry with typed GetServiceAs[T] helper

All added to ServiceDeps for plugin consumption.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

auth/public_users.go

@@ -0,0 +1,25 @@
+package auth
+
+import (
+	"context"
+
+	"github.com/google/uuid"
+)
+
+// PublicUsers provides public/community user profile access for plugins.
+type PublicUsers interface {
+	GetByUsername(ctx context.Context, username string) (*PublicUserProfile, error)
+	GetByID(ctx context.Context, id uuid.UUID) (*PublicUserProfile, error)
+}
+
+// PublicUserProfile is a plugin-facing view of a public user.
+type PublicUserProfile struct {
+	ID            uuid.UUID
+	Email         string
+	Username      string
+	DisplayName   string
+	AvatarURL     string
+	Bio           string
+	EmailVerified bool
+	Role          string
+}

menus/menus.go

@@ -0,0 +1,34 @@
+package menus
+
+import (
+	"context"
+
+	"github.com/google/uuid"
+)
+
+// Menus provides menu and navigation access for plugins.
+type Menus interface {
+	GetMenuByName(ctx context.Context, name string) (*Menu, error)
+	GetMenuItems(ctx context.Context, menuID uuid.UUID) ([]MenuItem, error)
+}
+
+// Menu represents a named navigation menu.
+type Menu struct {
+	ID   uuid.UUID
+	Name string
+}
+
+// MenuItem represents a single entry in a navigation menu.
+type MenuItem struct {
+	ID           uuid.UUID
+	MenuID       uuid.UUID
+	Label        string
+	URL          string
+	PageSlug     string
+	ParentID     *uuid.UUID
+	SortOrder    int32
+	OpenInNewTab bool
+	CssClass     string
+	ItemType     string
+	Icon         string
+}

plugin/bridge.go

@@ -0,0 +1,22 @@
+package plugin
+
+// PluginBridge allows plugins to share services with each other.
+// Plugins register named services during startup; other plugins look them up at runtime.
+type PluginBridge interface {
+	RegisterService(pluginName, serviceName string, service any)
+	GetService(pluginName, serviceName string) any
+}
+
+// GetServiceAs retrieves a typed service from the bridge.
+func GetServiceAs[T any](bridge PluginBridge, pluginName, serviceName string) (T, bool) {
+	var zero T
+	if bridge == nil {
+		return zero, false
+	}
+	svc := bridge.GetService(pluginName, serviceName)
+	if svc == nil {
+		return zero, false
+	}
+	typed, ok := svc.(T)
+	return typed, ok
+}

plugin/deps.go

@@ -5,10 +5,13 @@ import (
 
 	"connectrpc.com/connect"
 	"git.dev.alexdunmow.com/block/core/ai"
+	"git.dev.alexdunmow.com/block/core/auth"
 	"git.dev.alexdunmow.com/block/core/content"
 	"git.dev.alexdunmow.com/block/core/crypto"
 	"git.dev.alexdunmow.com/block/core/gating"
+	"git.dev.alexdunmow.com/block/core/menus"
 	"git.dev.alexdunmow.com/block/core/settings"
+	"git.dev.alexdunmow.com/block/core/subscriptions"
 )
 
 // ServiceDeps provides dependencies that plugins need for RPC service handlers.
@@ -18,6 +21,9 @@ type ServiceDeps struct {
 	Settings      settings.Settings
 	Gating        gating.Gating
 	Crypto        crypto.Crypto
+	Menus         menus.Menus
+	PublicUsers   auth.PublicUsers
+	Subscriptions subscriptions.Subscriptions
 
 	// Database — for plugin's own sqlc queries
 	Pool Pool
@@ -36,6 +42,9 @@ type ServiceDeps struct {
 	// Email
 	EmailSender EmailSender
 
+	// Plugin interop
+	Bridge PluginBridge
+
 	// Extension points — typed as narrow interfaces where possible
 	JobRunner        JobRunner
 	EmbeddingService EmbeddingService

subscriptions/subscriptions.go

@@ -0,0 +1,44 @@
+package subscriptions
+
+import (
+	"context"
+	"time"
+
+	"github.com/google/uuid"
+)
+
+// Subscriptions provides subscription tier and billing plan access for plugins.
+type Subscriptions interface {
+	GetUserTierLevel(ctx context.Context, userID uuid.UUID) (*TierLevel, error)
+	GetTierBySlug(ctx context.Context, slug string) (*Tier, error)
+	ListActivePlans(ctx context.Context, tierID uuid.UUID) ([]Plan, error)
+}
+
+// TierLevel is the resolved tier for a user.
+type TierLevel struct {
+	Level    int
+	Features []byte
+}
+
+// Tier is a subscription tier definition.
+type Tier struct {
+	ID          uuid.UUID
+	Name        string
+	Slug        string
+	Level       int
+	Description string
+	Features    []byte
+	IsDefault   bool
+	Position    int
+}
+
+// Plan is an active billing plan within a tier.
+type Plan struct {
+	ID              uuid.UUID
+	TierID          uuid.UUID
+	BillingInterval string
+	Amount          int32
+	Currency        string
+	IsActive        bool
+	CreatedAt       time.Time
+}