Wire up cache, file watcher, and Unix socket daemon

Adds a gen_server cache holding the rendered menu, an fs/inotify-based
watcher that debounces changes and invalidates it, a Unix domain
socket serving the cached binary, and the escript client Openbox
invokes (with an inline render fallback if the daemon isn't running).
Also documents local deployment (systemd user unit, Openbox menu.xml
wiring) in the README.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

1 files changed, 41 insertions, 0 deletions

diff --git a/src/er_xdg_pipe_menu_cli.erl b/src/er_xdg_pipe_menu_cli.erl
new file mode 100644
index 0000000..92ac715
--- /dev/null
+++ b/src/er_xdg_pipe_menu_cli.erl
@@ -0,0 +1,41 @@
+%%%-------------------------------------------------------------------
+%% @doc Entry point invoked by Openbox as the pipe menu command.
+%%
+%% Tries the running daemon's Unix socket first for an instant,
+%% pre-rendered response; if the daemon isn't reachable, falls back to
+%% scanning, parsing and rendering inline so the menu still works.
+%% @end
+%%%-------------------------------------------------------------------
+
+-module(er_xdg_pipe_menu_cli).
+
+-export([main/1]).
+
+-define(CONNECT_TIMEOUT_MS, 200).
+-define(RECV_TIMEOUT_MS, 1000).
+
+main(_Args) ->
+    Menu =
+        case from_daemon() of
+            {ok, Bin} -> Bin;
+            error -> er_xdg_pipe_menu_cache:build(er_xdg_pipe_menu_scanner:data_dirs())
+        end,
+    io:put_chars(Menu).
+
+from_daemon() ->
+    Path = er_xdg_pipe_menu_socket:socket_path(),
+    case gen_tcp:connect({local, Path}, 0, [binary, {active, false}], ?CONNECT_TIMEOUT_MS) of
+        {ok, Socket} ->
+            Result = recv_all(Socket, []),
+            gen_tcp:close(Socket),
+            Result;
+        {error, _Reason} ->
+            error
+    end.
+
+recv_all(Socket, Acc) ->
+    case gen_tcp:recv(Socket, 0, ?RECV_TIMEOUT_MS) of
+        {ok, Data} -> recv_all(Socket, [Data | Acc]);
+        {error, closed} -> {ok, iolist_to_binary(lists:reverse(Acc))};
+        {error, _Reason} -> error
+    end.