fix(settings): search_provider_id NULL scan failure

The ::text cast on search_providers.id prevented sqlc from inferring
nullability via LEFT JOIN, generating a non-nullable string field that
crashes when the bot has no search provider bound.

db/queries/settings.sql

@@ -7,7 +7,7 @@ SELECT
   chat_models.model_id AS chat_model_id,
   memory_models.model_id AS memory_model_id,
   embedding_models.model_id AS embedding_model_id,
-  search_providers.id::text AS search_provider_id
+  search_providers.id AS search_provider_id
 FROM bots
 LEFT JOIN models AS chat_models ON chat_models.id = bots.chat_model_id
 LEFT JOIN models AS memory_models ON memory_models.id = bots.memory_model_id
@@ -37,7 +37,7 @@ SELECT
   chat_models.model_id AS chat_model_id,
   memory_models.model_id AS memory_model_id,
   embedding_models.model_id AS embedding_model_id,
-  search_providers.id::text AS search_provider_id
+  search_providers.id AS search_provider_id
 FROM updated
 LEFT JOIN models AS chat_models ON chat_models.id = updated.chat_model_id
 LEFT JOIN models AS memory_models ON memory_models.id = updated.memory_model_id

internal/db/sqlc/settings.sql.go

@@ -38,7 +38,7 @@ SELECT
   chat_models.model_id AS chat_model_id,
   memory_models.model_id AS memory_model_id,
   embedding_models.model_id AS embedding_model_id,
-  search_providers.id::text AS search_provider_id
+  search_providers.id AS search_provider_id
 FROM bots
 LEFT JOIN models AS chat_models ON chat_models.id = bots.chat_model_id
 LEFT JOIN models AS memory_models ON memory_models.id = bots.memory_model_id
@@ -55,7 +55,7 @@ type GetSettingsByBotIDRow struct {
 	ChatModelID        pgtype.Text `json:"chat_model_id"`
 	MemoryModelID      pgtype.Text `json:"memory_model_id"`
 	EmbeddingModelID   pgtype.Text `json:"embedding_model_id"`
-	SearchProviderID   string      `json:"search_provider_id"`
+	SearchProviderID   pgtype.UUID `json:"search_provider_id"`
 }
 
 func (q *Queries) GetSettingsByBotID(ctx context.Context, id pgtype.UUID) (GetSettingsByBotIDRow, error) {
@@ -96,7 +96,7 @@ SELECT
   chat_models.model_id AS chat_model_id,
   memory_models.model_id AS memory_model_id,
   embedding_models.model_id AS embedding_model_id,
-  search_providers.id::text AS search_provider_id
+  search_providers.id AS search_provider_id
 FROM updated
 LEFT JOIN models AS chat_models ON chat_models.id = updated.chat_model_id
 LEFT JOIN models AS memory_models ON memory_models.id = updated.memory_model_id
@@ -123,7 +123,7 @@ type UpsertBotSettingsRow struct {
 	ChatModelID        pgtype.Text `json:"chat_model_id"`
 	MemoryModelID      pgtype.Text `json:"memory_model_id"`
 	EmbeddingModelID   pgtype.Text `json:"embedding_model_id"`
-	SearchProviderID   string      `json:"search_provider_id"`
+	SearchProviderID   pgtype.UUID `json:"search_provider_id"`
 }
 
 func (q *Queries) UpsertBotSettings(ctx context.Context, arg UpsertBotSettingsParams) (UpsertBotSettingsRow, error) {

internal/settings/service.go

@@ -7,6 +7,7 @@ import (
 	"log/slog"
 	"strings"
 
+	"github.com/google/uuid"
 	"github.com/jackc/pgx/v5/pgtype"
 
 	"github.com/memohai/memoh/internal/db"
@@ -175,13 +176,15 @@ func normalizeBotSettingsFields(
 	chatModelID pgtype.Text,
 	memoryModelID pgtype.Text,
 	embeddingModelID pgtype.Text,
-	searchProviderID string,
+	searchProviderID pgtype.UUID,
 ) Settings {
 	settings := normalizeBotSetting(maxContextLoadTime, language, allowGuest)
 	settings.ChatModelID = strings.TrimSpace(chatModelID.String)
 	settings.MemoryModelID = strings.TrimSpace(memoryModelID.String)
 	settings.EmbeddingModelID = strings.TrimSpace(embeddingModelID.String)
-	settings.SearchProviderID = strings.TrimSpace(searchProviderID)
+	if searchProviderID.Valid {
+		settings.SearchProviderID = uuid.UUID(searchProviderID.Bytes).String()
+	}
 	return settings
 }