1 files changed, 40 insertions, 0 deletions
diff --git a/src/loader/detect.h b/src/loader/detect.h
new file mode 100644
index 0000000..95e549c
--- /dev/null
+++ b/src/loader/detect.h
@@ -0,0 +1,40 @@
+#ifndef GGAZE_DETECT_H
+#define GGAZE_DETECT_H
+
+/*:*
+ * ggaze — image format detection
+ *
+ * Content-sniffing (magic bytes), never extension-based. detect_format() takes
+ * the first N bytes of a file and returns the detected GgazeFormat. The loader
+ * uses this to dispatch to the right backend; see docs/architecture.md "Image
+ * decode" and docs/tech-stack.md.
+ *
+ * Copyright (c) 2026 ggaze contributors
+ * SPDX-License-Identifier: GPL-3.0-or-later
+ *:*/
+
+#include <glib.h>
+
+G_BEGIN_DECLS
+
+typedef enum {
+   GGAZE_FMT_UNKNOWN = 0,
+   GGAZE_FMT_JPEG,    /* FF D8 FF */
+   GGAZE_FMT_PNG,     /* 89 50 4E 47 0D 0A 1A 0A */
+   GGAZE_FMT_GIF,     /* "GIF8" */
+   GGAZE_FMT_WEBP,    /* RIFF .... WEBP */
+   GGAZE_FMT_TIFF,    /* II 2A 00 | MM 00 2A */
+   GGAZE_FMT_ICO,     /* 00 00 01 00 */
+   GGAZE_FMT_JXL,     /* FF 0A | "....JXL " container */
+   GGAZE_FMT_AVIF,    /* ftyp avif/avis */
+   GGAZE_FMT_HEIF     /* ftyp heic/heix/mif1 */
+} GgazeFormat;
+
+/* Sniff p_head (u_len bytes) and return the detected format. Never reads
+ * past u_len. Returns GGAZE_FMT_UNKNOWN if the buffer is too short or
+ * unrecognized. */
+GgazeFormat detect_format(const guint8 *p_head, gsize u_len);
+
+G_END_DECLS
+
+#endif /* GGAZE_DETECT_H */
+\ No newline at end of file