Log detailed error bodies for UI failures

cpp/runtime_components.cpp

@@ -288,7 +288,11 @@ void Scheduler::worker_loop() {
             }
             registry_.complete(ctx, RequestState::DONE, {status, body});
         } catch (const std::exception &e) {
+            log_line("request_id=" + ctx->request_id + " scheduler_exception=" + std::string(e.what()));
             registry_.complete(ctx, RequestState::FAILED, {500, json({{"error", e.what()}}).dump()});
+        } catch (...) {
+            log_line("request_id=" + ctx->request_id + " scheduler_exception=unknown");
+            registry_.complete(ctx, RequestState::FAILED, {500, json({{"error", "Unknown exception"}}).dump()});
         }
     }
 }

cpp/server.cpp

@@ -212,8 +212,13 @@ http::response<http::string_body> handle_request(
         auto elapsed_ms = std::chrono::duration_cast<std::chrono::milliseconds>(
             std::chrono::steady_clock::now() - start).count();
         metrics.observe_request_latency_ms(elapsed_ms);
-        log_line("request_id=" + request_id + " status=" + std::to_string(res.result_int()) +
-                 " elapsed_ms=" + std::to_string(elapsed_ms));
+        std::string log_message = "request_id=" + request_id +
+                                  " status=" + std::to_string(res.result_int()) +
+                                  " elapsed_ms=" + std::to_string(elapsed_ms);
+        if (res.result_int() >= 400) {
+            log_message += " error_body=" + truncate_body(res.body());
+        }
+        log_line(log_message);
         return res;
     };
 
@@ -442,6 +447,10 @@ http::response<http::string_body> handle_request(
                      " final_state=" + state_to_string(final_state) +
                      " upstream_status=" + std::to_string(result.status) +
                      " elapsed_ms=" + std::to_string(elapsed_ms));
+            if (result.status >= 400) {
+                log_line("request_id=" + request_id +
+                         " upstream_error_body=" + truncate_body(result.body));
+            }
             return res;
         }
 
@@ -468,12 +477,20 @@ http::response<http::string_body> handle_request(
                      " proxied_get model=" + worker->model +
                      " upstream_status=" + std::to_string(upstream.status) +
                      " elapsed_ms=" + std::to_string(elapsed_ms));
+            if (upstream.status >= 400) {
+                log_line("request_id=" + request_id +
+                         " proxied_get_error_body=" + truncate_body(upstream.body));
+            }
             return res;
         }
 
         return json_response(http::status::not_found, {{"error", "Not found"}});
     } catch (const std::exception &e) {
+        log_line("request_id=" + request_id + " exception=" + std::string(e.what()));
         return json_response(http::status::internal_server_error, {{"error", e.what()}});
+    } catch (...) {
+        log_line("request_id=" + request_id + " exception=unknown");
+        return json_response(http::status::internal_server_error, {{"error", "Unknown exception"}});
     }
 }
 
@@ -494,6 +511,9 @@ void do_session(
         http::write(socket, res);
         beast::error_code ec;
         socket.shutdown(boost::asio::ip::tcp::socket::shutdown_send, ec);
+    } catch (const std::exception &e) {
+        log_line("session_exception=" + std::string(e.what()));
     } catch (...) {
+        log_line("session_exception=unknown");
     }
 }