feat(03-03): add typed path params and per-plugin rollback

Compile regex and enum constraints at route registration so malformed and unknown IDs share a 404, and named rollback errors isolate one plugin's history.

Co-authored-by: Cursor <cursoragent@cursor.com>

lagoon/migrations.go

@@ -1,6 +1,7 @@
 package lagoon
 
 import (
+	"errors"
 	"fmt"
 	"strings"
 	"unicode"
@@ -13,6 +14,13 @@ import (
 
 const historyTablePrefix = "summer_migrations_"
 
+var (
+	// ErrUnknownPlugin is returned when migrate:rollback names a plugin that is not activated.
+	ErrUnknownPlugin = errors.New("lagoon: plugin is not activated")
+	// ErrNoMigrations is returned when there is no plugin migration set to roll back.
+	ErrNoMigrations = errors.New("lagoon: no plugin migrations to roll back")
+)
+
 // HistoryTableName returns the isolated gormigrate table for pluginID.
 func HistoryTableName(pluginID string) (string, error) {
 	if err := validatePluginID(pluginID); err != nil {
@@ -83,26 +91,30 @@ func RollbackLast(gdb *gorm.DB, plugins []party.Plugin, pluginID string) error {
 		pluginID = lastMigrationPlugin(plugins)
 	}
 	if pluginID == "" {
-		return fmt.Errorf("lagoon: no plugin migrations to roll back")
+		return ErrNoMigrations
 	}
+	var target party.Plugin
 	for _, p := range plugins {
-		if p.ID() != pluginID {
-			continue
+		if p.ID() == pluginID {
+			target = p
+			break
 		}
-		hm, ok := p.(pact.HasMigrations)
-		if !ok {
-			return fmt.Errorf("lagoon: plugin %q has no migrations", pluginID)
-		}
-		m, err := migrator(gdb, p.ID(), hm.Migrations())
-		if err != nil {
-			return err
-		}
-		if err := m.RollbackLast(); err != nil {
-			return fmt.Errorf("lagoon: rollback %s: %w", pluginID, err)
-		}
-		return nil
 	}
-	return fmt.Errorf("lagoon: plugin %q is not activated", pluginID)
+	if target == nil {
+		return fmt.Errorf("%w: %q", ErrUnknownPlugin, pluginID)
+	}
+	hm, ok := target.(pact.HasMigrations)
+	if !ok || len(hm.Migrations()) == 0 {
+		return fmt.Errorf("%w: %q", ErrNoMigrations, pluginID)
+	}
+	m, err := migrator(gdb, target.ID(), hm.Migrations())
+	if err != nil {
+		return err
+	}
+	if err := m.RollbackLast(); err != nil {
+		return fmt.Errorf("lagoon: rollback %s: %w", pluginID, err)
+	}
+	return nil
 }
 
 func lastMigrationPlugin(plugins []party.Plugin) string {