fed-sx-m1: Step 8b-route — http_server:route/1 pure dispatch + ok/not_found helpers + 11 tests

next/kernel/http_server.erl

@@ -0,0 +1,49 @@
+-module(http_server).
+-export([route/1, ok_response/1, not_found_response/0, welcome_body/0]).
+
+%% HTTP request router per design §16.1.
+%%
+%% Request shape (mirrors what the SX-side `http-listen` builds and
+%% the http:listen/2 BIF bridge marshals into a proplist):
+%%   [{method, Binary}, {path, Binary}, {query, Binary},
+%%    {headers, [{Name, Value}, ...]}, {body, Binary}]
+%%
+%% Response shape:
+%%   [{status, Integer}, {headers, [{Name, Value}, ...]}, {body, Binary}]
+%%
+%% Real dispatch (actor docs, outbox listings, /activity POST,
+%% /.well-known/sx-capabilities, etc.) lands in Step 8c+. Step 8b
+%% wires the route/1 shape and a single hello-world handler that
+%% proves the request→response round-trip.
+%%
+%% Method/path comparison uses integer-segment binaries because
+%% `<<"GET">>` truncates to a single byte in this port.
+
+route(Req) ->
+    M = field(method, Req),
+    P = field(path, Req),
+    dispatch(M, P).
+
+%% 71 69 84 = "GET"  | 47 = "/"
+dispatch(<<71, 69, 84>>, <<47>>) ->
+    ok_response(welcome_body());
+dispatch(_, _) ->
+    not_found_response().
+
+%% "fed-sx kernel m1\n" — 17 bytes, hand-spelled.
+%%  f  e  d  -  s  x   _   k   e   r   n   e   l   _   m   1   \n
+welcome_body() ->
+    <<102,101,100,45,115,120,32,107,101,114,110,101,108,32,109,49,10>>.
+
+ok_response(Body) ->
+    [{status, 200}, {headers, []}, {body, Body}].
+
+not_found_response() ->
+    [{status, 404}, {headers, []},
+     {body, <<110,111,116,32,102,111,117,110,100,10>>}].  % "not found\n"
+
+%% Internal property-list field lookup. Returns nil when missing
+%% so the route falls into the not_found arm gracefully.
+field(K, [{K, V} | _]) -> V;
+field(K, [_ | Rest]) -> field(K, Rest);
+field(_, []) -> nil.