--- a/seobeo/seobeo.h	Tue Aug 04 16:49:01 2026 -0700
+++ b/seobeo/seobeo.h	Tue Aug 04 16:49:11 2026 -0700
@@ -27,6 +27,10 @@
 
 
 #define INITIAL_BUFFER_CAPACITY 4096
+#define SEOBEO_SSE_RETRY_NONE -1
+#define SEOBEO_SSE_EVENT_TOO_LARGE -2
+#define SEOBEO_SSE_INVALID_EVENT -3
+#define SEOBEO_SSE_BACKPRESSURE -4
 
 // HTTP STATUS CODE
 #define HTTP_OK 200
@@ -342,6 +346,8 @@
 extern void                  Seobeo_Router_Register(const char *method, const char *path_pattern, Seobeo_Route_Handler handler);
 /* Register a streaming route handler. Handler receives client handle for direct streaming. */
 extern void                  Seobeo_Router_Register_Stream(const char *method, const char *path_pattern, Seobeo_Stream_Handler handler);
+/* Register a GET route that owns an SSE stream until its handler returns. */
+extern void                  Seobeo_Router_Register_SSE(const char *path_pattern, Seobeo_SSE_Handler handler);
 /* Clean up router resources */
 extern void                  Seobeo_Router_Destroy();
 /* Find matching route handler (internal use) */
@@ -353,16 +359,36 @@
 extern char                 *Seobeo_Web_LoadFile(const char *file_path, size_t *p_file_size);
 /* Being a proxy and keeping the client open */
 extern Seobeo_Stream_Handler Seobeo_Router_Find_Stream_Handler(const char *method, const char *path, Seobeo_Request_Entry **pp_request_map, Dowa_Arena *p_arena);
+extern Seobeo_SSE_Handler    Seobeo_Router_Find_SSE_Handler(const char *method, const char *path, Seobeo_Request_Entry **pp_request_map, Dowa_Arena *p_arena);
+
+/* Start an SSE response and send its required HTTP headers. */
+extern int32          Seobeo_SSE_Start(Seobeo_SSE_Stream *p_stream, Seobeo_Handle *p_handle);
+/* Send one SSE record. retry_ms may be SEOBEO_SSE_RETRY_NONE. */
+extern int32          Seobeo_SSE_Send(Seobeo_SSE_Stream *p_stream, const Seobeo_SSE_Event *p_event);
+/* Send a data-only SSE record. */
+extern int32          Seobeo_SSE_Send_Data(Seobeo_SSE_Stream *p_stream, const char *data);
+/* Send a comment/heartbeat record. */
+extern int32          Seobeo_SSE_Send_Comment(Seobeo_SSE_Stream *p_stream, const char *comment);
+/* Flush queued SSE bytes. Returns 1 when the socket would block. */
+extern int32          Seobeo_SSE_Flush(Seobeo_SSE_Stream *p_stream);
+/* Return TRUE while the stream can still accept records. */
+extern boolean        Seobeo_SSE_Is_Open(const Seobeo_SSE_Stream *p_stream);
+/* Retain a stream before storing it beyond the connection callback. */
+extern boolean        Seobeo_SSE_Retain(Seobeo_SSE_Stream *p_stream);
+/* Release a previously retained stream. */
+extern void           Seobeo_SSE_Release(Seobeo_SSE_Stream *p_stream);
+/* Stop accepting records. The router retains ownership of the handle. */
+extern void           Seobeo_SSE_Close(Seobeo_SSE_Stream *p_stream);
 
 // --- Helper functions --- //
 /* Destroy handle. It will handle all NULL poointers. */
 extern void           Seobeo_Handle_Destroy(Seobeo_Handle *p_handle);
 /* Write to socket from write_buffer in the handle. */
-extern int            Seobeo_Handle_Flush(Seobeo_Handle *p_handle); 
+extern int32          Seobeo_Handle_Flush(Seobeo_Handle *p_handle);
 /* Write to socket with given data source, if the data source is bigger than the write buffer for handle then we just directly write from the data source. */
-extern int            Seobeo_Handle_Queue(Seobeo_Handle *p_handle, const uint8_t *data, uint32_t data_size); 
+extern int32          Seobeo_Handle_Queue(Seobeo_Handle *p_handle, const uint8 *data, uint32 data_size);
 /* Read to socket from read_buffer in the handle. */
-extern int            Seobeo_Handle_Read(Seobeo_Handle *p_handle); 
+extern int32          Seobeo_Handle_Read(Seobeo_Handle *p_handle);
 /* Move to read_buffer to front and we already consumed the given amount in the handle. */
 extern void           Seobeo_Handle_Consume(Seobeo_Handle *p_handle, uint32 consumed);
 /* Assign IP4 or IP6 to sockaddr. TODO: Maybe create my own struct for this? */