diff --git a/backend/internal/integration/server_test.go b/backend/internal/integration/server_test.go
index 0b102af..e1a2e7f 100644
--- a/backend/internal/integration/server_test.go
+++ b/backend/internal/integration/server_test.go
@@ -16,6 +16,8 @@ import (
 	"context"
 	"encoding/json"
 	"fmt"
+	"image"
+	"image/jpeg"
 	"io"
 	"mime/multipart"
 	"net"
@@ -1575,41 +1577,25 @@ func TestPoolOperationsRequireACL(t *testing.T) {
 // Test helpers
 // ---------------------------------------------------------------------------
 
-// minimalJPEG returns the bytes of a 1×1 white JPEG image.
-// Generated offline; no external dependency needed.
+// minimalJPEG returns the bytes of a small solid-white JPEG produced by the
+// standard library encoder. Encoding is deterministic, so every call yields
+// byte-identical output — two uploads therefore hash to the same perceptual
+// hash (a solid image dHashes to 0), which is what the duplicate test relies on.
+//
+// It is encoded (rather than a hand-written byte literal) so the bytes decode
+// cleanly through image.Decode: that is the same path FileService.Upload takes
+// to compute the perceptual hash, and a fixture that only passes MIME sniffing
+// but fails to fully decode would leave phash NULL and silently break dedup.
 func minimalJPEG() []byte {
-	// This is a valid minimal JPEG: SOI + APP0 + DQT + SOF0 + DHT + SOS + EOI.
-	// 1×1 white pixel, quality ~50. Verified with `file` and browsers.
-	return []byte{
-		0xff, 0xd8, 0xff, 0xe0, 0x00, 0x10, 0x4a, 0x46, 0x49, 0x46, 0x00, 0x01,
-		0x01, 0x00, 0x00, 0x01, 0x00, 0x01, 0x00, 0x00, 0xff, 0xdb, 0x00, 0x43,
-		0x00, 0x08, 0x06, 0x06, 0x07, 0x06, 0x05, 0x08, 0x07, 0x07, 0x07, 0x09,
-		0x09, 0x08, 0x0a, 0x0c, 0x14, 0x0d, 0x0c, 0x0b, 0x0b, 0x0c, 0x19, 0x12,
-		0x13, 0x0f, 0x14, 0x1d, 0x1a, 0x1f, 0x1e, 0x1d, 0x1a, 0x1c, 0x1c, 0x20,
-		0x24, 0x2e, 0x27, 0x20, 0x22, 0x2c, 0x23, 0x1c, 0x1c, 0x28, 0x37, 0x29,
-		0x2c, 0x30, 0x31, 0x34, 0x34, 0x34, 0x1f, 0x27, 0x39, 0x3d, 0x38, 0x32,
-		0x3c, 0x2e, 0x33, 0x34, 0x32, 0xff, 0xc0, 0x00, 0x0b, 0x08, 0x00, 0x01,
-		0x00, 0x01, 0x01, 0x01, 0x11, 0x00, 0xff, 0xc4, 0x00, 0x1f, 0x00, 0x00,
-		0x01, 0x05, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x00, 0x00, 0x00, 0x00,
-		0x00, 0x00, 0x00, 0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08,
-		0x09, 0x0a, 0x0b, 0xff, 0xc4, 0x00, 0xb5, 0x10, 0x00, 0x02, 0x01, 0x03,
-		0x03, 0x02, 0x04, 0x03, 0x05, 0x05, 0x04, 0x04, 0x00, 0x00, 0x01, 0x7d,
-		0x01, 0x02, 0x03, 0x00, 0x04, 0x11, 0x05, 0x12, 0x21, 0x31, 0x41, 0x06,
-		0x13, 0x51, 0x61, 0x07, 0x22, 0x71, 0x14, 0x32, 0x81, 0x91, 0xa1, 0x08,
-		0x23, 0x42, 0xb1, 0xc1, 0x15, 0x52, 0xd1, 0xf0, 0x24, 0x33, 0x62, 0x72,
-		0x82, 0x09, 0x0a, 0x16, 0x17, 0x18, 0x19, 0x1a, 0x25, 0x26, 0x27, 0x28,
-		0x29, 0x2a, 0x34, 0x35, 0x36, 0x37, 0x38, 0x39, 0x3a, 0x43, 0x44, 0x45,
-		0x46, 0x47, 0x48, 0x49, 0x4a, 0x53, 0x54, 0x55, 0x56, 0x57, 0x58, 0x59,
-		0x5a, 0x63, 0x64, 0x65, 0x66, 0x67, 0x68, 0x69, 0x6a, 0x73, 0x74, 0x75,
-		0x76, 0x77, 0x78, 0x79, 0x7a, 0x83, 0x84, 0x85, 0x86, 0x87, 0x88, 0x89,
-		0x8a, 0x93, 0x94, 0x95, 0x96, 0x97, 0x98, 0x99, 0x9a, 0xa2, 0xa3, 0xa4,
-		0xa5, 0xa6, 0xa7, 0xa8, 0xa9, 0xaa, 0xb2, 0xb3, 0xb4, 0xb5, 0xb6, 0xb7,
-		0xb8, 0xb9, 0xba, 0xc2, 0xc3, 0xc4, 0xc5, 0xc6, 0xc7, 0xc8, 0xc9, 0xca,
-		0xd2, 0xd3, 0xd4, 0xd5, 0xd6, 0xd7, 0xd8, 0xd9, 0xda, 0xe1, 0xe2, 0xe3,
-		0xe4, 0xe5, 0xe6, 0xe7, 0xe8, 0xe9, 0xea, 0xf1, 0xf2, 0xf3, 0xf4, 0xf5,
-		0xf6, 0xf7, 0xf8, 0xf9, 0xfa, 0xff, 0xda, 0x00, 0x08, 0x01, 0x01, 0x00,
-		0x00, 0x3f, 0x00, 0xfb, 0xd3, 0xff, 0xd9,
+	img := image.NewGray(image.Rect(0, 0, 16, 16))
+	for i := range img.Pix {
+		img.Pix[i] = 0xff // white
 	}
+	var buf bytes.Buffer
+	if err := jpeg.Encode(&buf, img, &jpeg.Options{Quality: 75}); err != nil {
+		panic("minimalJPEG: encode: " + err.Error())
+	}
+	return buf.Bytes()
 }
 
 // replaceDSNDatabase returns a copy of dsn with the dbname parameter replaced.