restructure: move el compiler content into lang/

lang/examples/http-status-envelope.el

@@ -0,0 +1,33 @@
+// http-status-envelope.el — acceptance test for the __status__ HTTP envelope.
+//
+// Before fix: a handler returning {"__status__":401,"error":"unauthorized"}
+// went out as an HTTP 200 with the JSON body verbatim, so Cloud Run logs were
+// full of 200s for what should have been 4xx/5xx.
+//
+// After fix: when the response body's FIRST key is __status__, the runtime
+// reads the integer value as the HTTP status code and strips the marker from
+// the body before sending it to the client.
+//
+// Verify with curl:
+//   curl -i http://localhost:8081/auth   -> HTTP/1.1 401 Unauthorized
+//   curl -i http://localhost:8081/health -> HTTP/1.1 200 OK
+//   curl -i http://localhost:8081/oops   -> HTTP/1.1 503 Service Unavailable
+
+fn handle(method: String, path: String, body: String) -> String {
+    if path == "/auth" {
+        return "{\"__status__\":401,\"error\":\"unauthorized\"}"
+    }
+    if path == "/oops" {
+        return "{\"__status__\":503,\"error\":\"degraded\"}"
+    }
+    if path == "/health" {
+        return "{\"ok\":true}"
+    }
+    return "{\"__status__\":404,\"error\":\"not found\"}"
+}
+
+fn main() -> Int {
+    http_set_handler("handle")
+    http_serve(8081, "handle")
+    return 0
+}