fixes for storage managament

internal/app/files/secret_chat_files.go

@@ -0,0 +1,52 @@
+package files
+
+import (
+	"context"
+	"fmt"
+
+	"go.uber.org/zap"
+
+	"telesrv/internal/domain"
+)
+
+// DeleteEncryptedFileBlob deletes a secret-chat encrypted file's blob bytes
+// (location_key "enc:<id>") once the recipient has fully downloaded it --
+// see internal/rpc/upload.go's onUploadGetFile, which calls this after a
+// getFile response whose bytes reach the end of the file. Secret chats are
+// single-device on both ends (no multi-device sync, unlike ordinary chats),
+// so once the one recipient device that will ever ask for this ciphertext
+// has it, the server has no further reason to keep it -- unlike ordinary
+// message media, there is no "another device might still need to fetch
+// this" case to protect against.
+//
+// No-op unless TELESRV_SECRET_CHAT_DELETE_FILE_AFTER_DOWNLOAD is enabled
+// (WithSecretChatDeleteFileAfterDownload, default true). Best-effort: the
+// caller is a fire-and-forget goroutine off the download response, so
+// errors are only logged, never propagated -- a failed cleanup here must
+// never turn into a failed or delayed file download.
+func (s *Service) DeleteEncryptedFileBlob(ctx context.Context, locationKey string) error {
+	if !s.secretChatDeleteFileAfterDownload {
+		return nil
+	}
+	store, ok := s.media.(mediaRetentionStore)
+	if !ok {
+		return nil
+	}
+	blob, found, err := s.media.GetFileBlob(ctx, locationKey)
+	if err != nil {
+		return fmt.Errorf("get encrypted file blob: %w", err)
+	}
+	if !found {
+		// Already deleted (e.g. a racing duplicate getFile request for the
+		// same final chunk) -- nothing left to do.
+		return nil
+	}
+	if err := s.media.DeleteFileBlobRow(ctx, locationKey); err != nil {
+		return fmt.Errorf("delete encrypted file blob row: %w", err)
+	}
+	s.blobCache.delete(locationKey)
+	s.deleteOrphanedBlobs(ctx, store, []domain.FileBlob{blob})
+	s.log.Info("secret chat file deleted after download",
+		zap.String("location_key", locationKey), zap.Int64("size", blob.Size))
+	return nil
+}