refactor(dr-014): slim webserver_impl to a composition root

With all seven behavior services extracted, remove the now-dead
webserver_impl forwarders. The MHD-adapter trampolines that stayed
(connection_notify / policy_callback / request_completed) now call
impl_->hooks_dispatch_ directly instead of the fire_* forwarders.

Removed:
- hook_phase_dispatch.cpp (11 fire_* forwarders), webserver_hook_firing.cpp
  (4 gated fire_*_gated forwarders), webserver_response_queue.cpp
  (materialize_and_queue_response forwarder) — deleted entirely.
- The 404/405/500 forwarders from webserver_error_pages.cpp (which now
  holds only the log_dispatch_error forwarder, still used by the v1 alias
  hooks) and all the corresponding declarations from the fragment header.

webserver_impl now holds only: the 5 state collaborators, the 7 behavior
services, the parent back-pointer + digest_opaque_ + SNI cache, the thin
lookup_v2 / has_hooks_for / phase_hook_count / invalidate_route_cache
forwarders (test + trampoline seams), and the static MHD trampolines. No
request-processing logic remains on it.

113/113 tests pass; cpplint/complexity/file-size gates green.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

Author: etr

src/Makefile.am

@@ -25,7 +25,7 @@ lib_LTLIBRARIES = libhttpserver.la
 # builds. The WS-off branch in websocket_handler.cpp provides stub
 # definitions (every member throws feature_unavailable except is_valid()
 # which returns false).
-libhttpserver_la_SOURCES = string_utilities.cpp webserver.cpp webserver_add_hook.cpp http_utils.cpp file_info.cpp http_request.cpp http_request_auth.cpp http_response.cpp http_response_factories.cpp http_resource.cpp create_webserver.cpp create_test_request.cpp websocket_handler.cpp hook_handle.cpp peer_address.cpp resource_hook_table.cpp cookie.cpp detail/http_endpoint.cpp detail/body.cpp detail/ip_representation.cpp detail/ip_access_control.cpp detail/ws_registry.cpp detail/hook_bus.cpp detail/route_table.cpp detail/daemon_lifecycle.cpp detail/dispatch_util.cpp detail/error_pages.cpp detail/hook_dispatcher.cpp detail/http_request_impl.cpp detail/http_request_impl_args.cpp detail/http_request_impl_tls.cpp detail/request_dispatcher.cpp detail/request_pipeline.cpp detail/response_materializer.cpp detail/upload_pipeline.cpp detail/websocket_upgrader.cpp detail/webserver_lifecycle.cpp detail/webserver_register.cpp detail/webserver_routes.cpp detail/webserver_routes_upsert.cpp detail/webserver_callbacks.cpp detail/webserver_callbacks_lifecycle.cpp detail/webserver_dispatch.cpp detail/webserver_request.cpp detail/webserver_response_queue.cpp detail/webserver_body_pipeline.cpp detail/webserver_error_pages.cpp detail/webserver_aliases.cpp detail/webserver_hook_firing.cpp detail/hook_phase_dispatch.cpp
+libhttpserver_la_SOURCES = string_utilities.cpp webserver.cpp webserver_add_hook.cpp http_utils.cpp file_info.cpp http_request.cpp http_request_auth.cpp http_response.cpp http_response_factories.cpp http_resource.cpp create_webserver.cpp create_test_request.cpp websocket_handler.cpp hook_handle.cpp peer_address.cpp resource_hook_table.cpp cookie.cpp detail/http_endpoint.cpp detail/body.cpp detail/ip_representation.cpp detail/ip_access_control.cpp detail/ws_registry.cpp detail/hook_bus.cpp detail/route_table.cpp detail/daemon_lifecycle.cpp detail/dispatch_util.cpp detail/error_pages.cpp detail/hook_dispatcher.cpp detail/http_request_impl.cpp detail/http_request_impl_args.cpp detail/http_request_impl_tls.cpp detail/request_dispatcher.cpp detail/request_pipeline.cpp detail/response_materializer.cpp detail/upload_pipeline.cpp detail/websocket_upgrader.cpp detail/webserver_lifecycle.cpp detail/webserver_register.cpp detail/webserver_routes.cpp detail/webserver_routes_upsert.cpp detail/webserver_callbacks.cpp detail/webserver_callbacks_lifecycle.cpp detail/webserver_dispatch.cpp detail/webserver_request.cpp detail/webserver_body_pipeline.cpp detail/webserver_error_pages.cpp detail/webserver_aliases.cpp 
 # noinst_HEADERS: shipped in the tarball but NEVER installed under $prefix/include.
 # Detail headers (httpserver/detail/*.hpp) live here so they cannot leak to
 # downstream consumers — the public surface comes in through <httpserver.hpp>.

src/detail/hook_phase_dispatch.cpp

@@ -110,7 +110,7 @@ void webserver_impl::request_completed(void *cls, struct MHD_Connection *connect
         // answer_to_connection never ran (e.g., very early MHD failures),
         // mr->ws may be null; skip the fire site in that degenerate case.
         if (mr->ws != nullptr && mr->ws->impl_ != nullptr) {
-            mr->ws->impl_->fire_request_completed_gated(mr, toe);
+            mr->ws->impl_->hooks_dispatch_.fire_request_completed_gated(mr, toe);
         }
     }
 

src/detail/webserver_callbacks.cpp

@@ -181,7 +181,7 @@ void webserver_impl::connection_notify(void* cls, struct MHD_Connection* connect
             // registered: a single relaxed atomic load + branch.
             if (hooks_armed(::httpserver::hook_phase::connection_opened)) {
                 ::httpserver::connection_open_ctx ctx{resolve_peer()};
-                ws_impl->fire_connection_opened(ctx);
+                ws_impl->hooks_dispatch_.fire_connection_opened(ctx);
             }
             break;
         }
@@ -192,7 +192,7 @@ void webserver_impl::connection_notify(void* cls, struct MHD_Connection* connect
             // ordering choice is safe regardless and pins the contract.
             if (hooks_armed(::httpserver::hook_phase::connection_closed)) {
                 ::httpserver::connection_close_ctx ctx{resolve_peer()};
-                ws_impl->fire_connection_closed(ctx);
+                ws_impl->hooks_dispatch_.fire_connection_closed(ctx);
             }
             // MHD ordering guarantee: NOTIFY_COMPLETED fires before
             // NOTIFY_CLOSED for the same connection. By the time we reach
@@ -238,7 +238,7 @@ MHD_Result webserver_impl::policy_callback(void *cls, const struct sockaddr* add
     if (is_phase_armed(impl, ::httpserver::hook_phase::accept_decision)) {
         ::httpserver::accept_ctx ctx{
             make_peer_address(addr), accepted, reason};
-        impl->fire_accept_decision(ctx);
+        impl->hooks_dispatch_.fire_accept_decision(ctx);
     }
 
     return decision;

src/detail/webserver_callbacks_lifecycle.cpp

@@ -18,47 +18,25 @@
      USA
 */
 
-// Thin webserver_impl forwarders into the error_pages behavior service
-// and the log_dispatch_error free function (DR-014 §4.11). The real logic
-// moved to detail/error_pages.cpp and detail/dispatch_util.cpp. These
-// forwarders keep the existing in-class call sites
-// (not_found_page(mr) / log_dispatch_error(msg) / ...) compiling
-// unchanged during the migration; they are removed once every caller is
-// itself a service holding error_pages& / the config bag directly.
+// The 404/405/500 synthesis moved to the error_pages behavior service
+// (detail/error_pages.cpp, DR-014 §4.11) and their webserver_impl forwarders
+// were removed once every caller became a service holding error_pages&
+// directly. Only the log_dispatch_error forwarder remains: it is still called
+// via impl_ptr->log_dispatch_error(...) from the v1 alias hooks in
+// webserver_aliases.cpp, so the thin member survives (delegating to the
+// detail::log_dispatch_error free function over the config bag).
 
 #include "httpserver/webserver.hpp"
 #include "httpserver/detail/webserver_impl.hpp"
 
 #include <string_view>
 
 #include "httpserver/create_webserver.hpp"
-#include "httpserver/http_response.hpp"
 #include "httpserver/detail/dispatch_util.hpp"
 
 namespace httpserver {
 namespace detail {
 
-http_response webserver_impl::not_found_page(detail::modded_request* mr) const {
-    return errors_.not_found_page(mr);
-}
-
-http_response webserver_impl::method_not_allowed_page(
-        detail::modded_request* mr) const {
-    return errors_.method_not_allowed_page(mr);
-}
-
-http_response webserver_impl::internal_error_page(detail::modded_request* mr,
-                                                  std::string_view msg,
-                                                  bool force_our) const {
-    return errors_.internal_error_page(mr, msg, force_our);
-}
-
-http_response webserver_impl::run_internal_error_handler_safely(
-        detail::modded_request* mr,
-        std::string_view msg) const {
-    return errors_.run_internal_error_handler_safely(mr, msg);
-}
-
 void webserver_impl::log_dispatch_error(std::string_view msg) const noexcept {
     detail::log_dispatch_error(parent->config, msg);
 }