feat: add SSE process filter for stream parsing

noise-sse.el

@@ -50,5 +50,26 @@ Returns nil for empty or invalid events."
               (json-parse-string json-str)
             (error nil)))))))
 
+(defvar noise-sse--buffer ""
+  "Buffer for partial SSE event data.")
+
+(defun noise-sse--filter (proc string)
+  "Process filter for SSE connection.
+Buffers incoming STRING and processes complete events."
+  (setq noise-sse--buffer (concat noise-sse--buffer string))
+  (while (string-match "\n\n" noise-sse--buffer)
+    (let ((event-end (match-beginning 0))
+          (event-start 0))
+      (let ((event-str (substring noise-sse--buffer event-start event-end)))
+        (setq noise-sse--buffer
+              (substring noise-sse--buffer (+ event-end 2)))
+        (when-let ((event (noise-sse--parse-event event-str)))
+          (noise-sse--handle-event event))))))
+
+(defun noise-sse--handle-event (event)
+  "Handle a parsed SSE EVENT.
+This function will be overridden in noise-receive to process envelopes."
+  (message "SSE event received: %s" event))
+
 (provide 'noise-sse)
 ;;; noise-sse.el ends here

test/noise-sse-test.el

@@ -55,5 +55,26 @@
     (noise-sse--increase-reconnect-delay)
     (should (= 60 noise-sse--reconnect-delay))))
 
+(ert-deftest noise-sse--filter-processes-complete-event ()
+  "Process filter parses and calls handler for complete events."
+  (let ((processed-events '()))
+    (cl-letf (((symbol-function 'noise-sse--handle-event)
+               (lambda (event) (push event processed-events))))
+      (let ((noise-sse--buffer ""))
+        (noise-sse--filter nil "data: {\"type\":\"message\"}\n\n")
+        (should (= 1 (length processed-events)))
+        (should (hash-table-p (car processed-events)))))))
+
+(ert-deftest noise-sse--filter-buffers-incomplete-event ()
+  "Process filter buffers incomplete events until newline."
+  (let ((processed-events '()))
+    (cl-letf (((symbol-function 'noise-sse--handle-event)
+               (lambda (event) (push event processed-events))))
+      (let ((noise-sse--buffer ""))
+        (noise-sse--filter nil "data: {\"type\":\"message\"")
+        (should (= 0 (length processed-events)))
+        (noise-sse--filter nil "}\n\n")
+        (should (= 1 (length processed-events)))))))
+
 (provide 'noise-sse-test)
 ;;; noise-sse-test.el ends here