feat(core): add typed eventbus and domain extension points

core/extpoints/migration.go

@@ -0,0 +1,83 @@
+package extpoints
+
+import (
+	"io/fs"
+	"sync"
+)
+
+// MigrationEntry contains the migration filesystem and configuration for a plugin.
+type MigrationEntry struct {
+	PluginID string
+	FS       fs.FS
+	Dir      string
+}
+
+// MigrationExtension defines the interface for registering and querying plugin migrations.
+type MigrationExtension interface {
+	Register(pluginID string, fsys fs.FS, dir ...string)
+	Entries() []MigrationEntry
+	Get(pluginID string) (MigrationEntry, bool)
+}
+
+// MigrationRegistry collects and stores migration entries from plugins.
+type MigrationRegistry struct {
+	mu      sync.RWMutex
+	entries []MigrationEntry
+	lookup  map[string]MigrationEntry
+}
+
+// NewMigrationRegistry creates a new migration registry.
+func NewMigrationRegistry() *MigrationRegistry {
+	return &MigrationRegistry{
+		lookup: make(map[string]MigrationEntry),
+	}
+}
+
+// Register adds a migration entry for a plugin.
+// If dir is not specified, it defaults to "migrations".
+func (m *MigrationRegistry) Register(pluginID string, fsys fs.FS, dir ...string) {
+	m.mu.Lock()
+	defer m.mu.Unlock()
+
+	migrationDir := "migrations"
+	if len(dir) > 0 && dir[0] != "" {
+		migrationDir = dir[0]
+	}
+
+	entry := MigrationEntry{
+		PluginID: pluginID,
+		FS:       fsys,
+		Dir:      migrationDir,
+	}
+
+	// If entry already exists, update in-place; otherwise append
+	if _, exists := m.lookup[pluginID]; exists {
+		for i, e := range m.entries {
+			if e.PluginID == pluginID {
+				m.entries[i] = entry
+				break
+			}
+		}
+	} else {
+		m.entries = append(m.entries, entry)
+	}
+
+	m.lookup[pluginID] = entry
+}
+
+// Entries returns a copy of all registered migration entries in registration order.
+func (m *MigrationRegistry) Entries() []MigrationEntry {
+	m.mu.RLock()
+	defer m.mu.RUnlock()
+	res := make([]MigrationEntry, len(m.entries))
+	copy(res, m.entries)
+	return res
+}
+
+// Get retrieves the migration entry for a specific plugin ID.
+func (m *MigrationRegistry) Get(pluginID string) (MigrationEntry, bool) {
+	m.mu.RLock()
+	defer m.mu.RUnlock()
+	e, ok := m.lookup[pluginID]
+	return e, ok
+}