feat(sentry): decode zstd request bodies

go.mod

@@ -5,6 +5,7 @@ go 1.26.1
 require (
 	github.com/emersion/go-smtp v0.24.0
 	github.com/golang-jwt/jwt/v5 v5.3.1
+	github.com/klauspost/compress v1.18.0
 	github.com/modelcontextprotocol/go-sdk v1.4.0
 	github.com/prometheus/client_golang v1.23.2
 	github.com/prometheus/client_model v0.6.2

modules/sentry/handler.go

@@ -11,6 +11,8 @@ import (
 	"net/http"
 	"strings"
 
+	"github.com/klauspost/compress/zstd"
+
 	"github.com/buggregator/go-buggregator/internal/event"
 )
 
@@ -324,9 +326,21 @@ func decompress(data []byte, encoding string) []byte {
 		if d, err := decompressZlib(data); err == nil {
 			return d
 		}
+	case "zstd":
+		if d, err := decompressZstd(data); err == nil {
+			return d
+		}
 	}
 
 	// Auto-detect by magic bytes (Sentry SDKs sometimes omit the header).
+	if len(data) >= 4 {
+		// Zstd magic: 0x28 0xb5 0x2f 0xfd
+		if data[0] == 0x28 && data[1] == 0xb5 && data[2] == 0x2f && data[3] == 0xfd {
+			if d, err := decompressZstd(data); err == nil {
+				return d
+			}
+		}
+	}
 	if len(data) >= 2 {
 		// Gzip magic: 0x1f 0x8b
 		if data[0] == 0x1f && data[1] == 0x8b {
@@ -354,6 +368,15 @@ func decompressGzip(data []byte) ([]byte, error) {
 	return io.ReadAll(r)
 }
 
+func decompressZstd(data []byte) ([]byte, error) {
+	r, err := zstd.NewReader(bytes.NewReader(data))
+	if err != nil {
+		return nil, err
+	}
+	defer r.Close()
+	return io.ReadAll(r)
+}
+
 func decompressZlib(data []byte) ([]byte, error) {
 	r, err := zlib.NewReader(bytes.NewReader(data))
 	if err != nil {

modules/sentry/handler_test.go

@@ -8,6 +8,8 @@ import (
 	"strconv"
 	"strings"
 	"testing"
+
+	"github.com/klauspost/compress/zstd"
 )
 
 func TestHandler_Priority(t *testing.T) {
@@ -152,6 +154,39 @@ func TestDecompress(t *testing.T) {
 		}
 	})
 
+	// sentry-php sends Content-Encoding: zstd by default since 4.x. Without zstd
+	// support the body stays compressed, fails to parse as an envelope and the
+	// event is dropped silently — the request still answers 200.
+	t.Run("zstd with header", func(t *testing.T) {
+		var buf bytes.Buffer
+		w, err := zstd.NewWriter(&buf)
+		if err != nil {
+			t.Fatalf("zstd writer: %v", err)
+		}
+		w.Write([]byte("zstd payload"))
+		w.Close()
+
+		got := decompress(buf.Bytes(), "zstd")
+		if string(got) != "zstd payload" {
+			t.Errorf("got %q, want %q", got, "zstd payload")
+		}
+	})
+
+	t.Run("zstd auto-detect by magic bytes", func(t *testing.T) {
+		var buf bytes.Buffer
+		w, err := zstd.NewWriter(&buf)
+		if err != nil {
+			t.Fatalf("zstd writer: %v", err)
+		}
+		w.Write([]byte("zstd auto-detected"))
+		w.Close()
+
+		got := decompress(buf.Bytes(), "")
+		if string(got) != "zstd auto-detected" {
+			t.Errorf("got %q, want %q", got, "zstd auto-detected")
+		}
+	})
+
 	t.Run("empty data", func(t *testing.T) {
 		got := decompress([]byte{}, "gzip")
 		if len(got) != 0 {