From d2a06ebbbe5ec101fbb73fa9b645d70aab41b6b2 Mon Sep 17 00:00:00 2001
From: Tulir Asokan <tulir@maunium.net>
Date: Tue, 28 Apr 2026 16:09:13 +0300
Subject: [PATCH] capabilities: mark lottie and webm as allowed sticker formats

---
 pkg/connector/capabilities.go  |  6 +++---
 pkg/connector/handlematrix.go  | 10 +++++++++-
 pkg/connector/media/sticker.go | 24 ++++++++++++++++++++++++
 3 files changed, 36 insertions(+), 4 deletions(-)

diff --git a/pkg/connector/capabilities.go b/pkg/connector/capabilities.go
index b306f504..c27a223c 100644
--- a/pkg/connector/capabilities.go
+++ b/pkg/connector/capabilities.go
@@ -145,9 +145,9 @@ var fileCaps = event.FileFeatureMap{
 			// These are converted to webp
 			"image/jpeg": event.CapLevelPartialSupport,
 			"image/png":  event.CapLevelPartialSupport,
-			// TODO
-			//"video/lottie+json": event.CapLevelFullySupported,
-			//"video/webm": event.CapLevelFullySupported,
+			// These will only go through if they're from an imported Telegram pack
+			"video/lottie+json": event.CapLevelPartialSupport,
+			"video/webm":        event.CapLevelPartialSupport,
 		},
 	},
 	event.CapMsgVoice: {
diff --git a/pkg/connector/handlematrix.go b/pkg/connector/handlematrix.go
index 62e3f4fe..1a013347 100644
--- a/pkg/connector/handlematrix.go
+++ b/pkg/connector/handlematrix.go
@@ -54,6 +54,7 @@ import (
 	"maunium.net/go/mautrix/event"
 	"maunium.net/go/mautrix/id"
 
+	"go.mau.fi/mautrix-telegram/pkg/connector/media"
 	"go.mau.fi/mautrix-telegram/pkg/gotd/telegram/message"
 	"go.mau.fi/mautrix-telegram/pkg/gotd/telegram/uploader"
 	"go.mau.fi/mautrix-telegram/pkg/gotd/tg"
@@ -275,10 +276,17 @@ func (tc *TelegramClient) transferMediaToTelegram(ctx context.Context, content *
 		} else if sticker && (info.MimeType != "video/webm" && info.MimeType != "application/x-tgsticker") {
 			uploadFilename, err = ffmpeg.ConvertPath(ctx, uploadFilename, ".webp", []string{}, []string{}, false)
 			if err != nil {
-				return fmt.Errorf("failed to convert sticker to webm: %+w", err)
+				return fmt.Errorf("failed to convert sticker to webm: %w", err)
 			}
 			defer os.Remove(uploadFilename)
 			info.MimeType = "image/webp"
+		} else if sticker && info.MimeType == "video/lottie+json" {
+			uploadFilename, err = media.CompressGZip(f)
+			if err != nil {
+				return fmt.Errorf("failed to compress lottie sticker: %w", err)
+			}
+			defer os.Remove(uploadFilename)
+			info.MimeType = "application/x-tgsticker"
 		} else if cfg, _, err := image.DecodeConfig(f); err != nil {
 			forceDocument = true
 		} else if fileInfo, err := f.Stat(); err != nil {
diff --git a/pkg/connector/media/sticker.go b/pkg/connector/media/sticker.go
index 160df901..e5f4c521 100644
--- a/pkg/connector/media/sticker.go
+++ b/pkg/connector/media/sticker.go
@@ -110,6 +110,30 @@ func (c *AnimatedStickerConfig) convertWebm(ctx context.Context, src *os.File) *
 	}
 }
 
+func CompressGZip(src *os.File) (replPath string, err error) {
+	tempFile, err := os.CreateTemp("", "telegram-sticker-gzip-*.tgs")
+	if err != nil {
+		return "", fmt.Errorf("failed to create temp file: %w", err)
+	}
+	writer := gzip.NewWriter(tempFile)
+	defer func() {
+		_ = tempFile.Close()
+		_ = writer.Close()
+		if replPath == "" {
+			_ = os.Remove(tempFile.Name())
+		}
+	}()
+	_, err = io.Copy(writer, src)
+	if err != nil {
+		return "", fmt.Errorf("failed to compress lottie gzip: %w", err)
+	}
+	err = writer.Close()
+	if err != nil {
+		return "", fmt.Errorf("failed to close gzip writer: %w", err)
+	}
+	return tempFile.Name(), nil
+}
+
 func extractGZip(src *os.File) (*ConvertedSticker, error) {
 	reader, err := gzip.NewReader(src)
 	if err != nil {