feat(chat): optimistic echo and moderation delivery notices

api/chat.lua

@@ -44,15 +44,56 @@ local function make_not_enabled_cb()
 	end
 end
 
+-- How much of a message to quote when attributing a failed send to it (item
+-- 2: with several sends in flight -- the fast-typing case that triggers rate
+-- limiting -- the player needs to tell which one a notice is about). Long
+-- enough to recognize at a glance, short enough to stay on one line.
+local NOTICE_QUOTE_MAX = 30
+
+local function quote_for_notice(text)
+	return '"' .. MPAPI.truncate(text, NOTICE_QUOTE_MAX) .. '"'
+end
+
 local function make_publish_fn(lobby)
 	return function(text)
 		if not MPAPI.config.chat_enabled then
 			MPAPI.chat.addMessage(localize('k_chat_client_disabled'), COLOUR_SYSTEM)
 			return
 		end
-		MPAPI._internal.send_chat_message(lobby.code, text, function(err, _)
+		-- The server rejects whitespace-only messages; don't echo them either.
+		if text:match('^%s*$') then
+			return
+		end
+		-- Optimistic echo: the sender sees their message the instant they hit
+		-- enter rather than after the round trip. The log is append-only on
+		-- both backends (DebugPlus owns its own log and hands back no handle),
+		-- so a line cannot be retracted or recoloured afterwards -- instead a
+		-- failure notice below quotes the message it refers to, which also
+		-- disambiguates several sends in flight.
+		local own_name = MPAPI.chat._own_name or localize('k_you')
+		MPAPI.chat.addMessage(own_name .. ': ' .. text, COLOUR_OWN)
+
+		MPAPI._internal.send_chat_message(lobby.code, text, function(err, data)
 			if err then
-				MPAPI.chat.addMessage('[!] ' .. tostring(err), COLOUR_SYSTEM)
+				-- Client-side failures (offline, transport, an unreadable
+				-- server response) don't carry player-facing copy -- only
+				-- ErrorKind.SERVER does -- so those get a generic reason
+				-- instead of leaking transport/proxy jargon.
+				local reason = tostring(err)
+				if err.kind ~= MPAPI.ErrorKind.SERVER then
+					reason = localize('k_chat_reason_unavailable')
+				end
+				MPAPI.chat.addMessage(
+					localize('k_chat_not_sent') .. ' ' .. quote_for_notice(text) .. ': ' .. reason,
+					COLOUR_SYSTEM
+				)
+				return
+			end
+
+			if data and type(data.publishText) == 'string' and data.publishText ~= text then
+				-- Moderation rewrote the message; the echo above showed the raw
+				-- form, so tell the sender what other players actually got.
+				MPAPI.chat.addMessage(localize('k_chat_sent_as') .. ' ' .. data.publishText, COLOUR_SYSTEM)
 			end
 		end)
 	end
@@ -74,9 +115,15 @@ local function subscribe_chat(lobby)
 			return
 		end
 
+		-- Own messages are rendered directly from the send result (see
+		-- make_publish_fn), never from this subscription; drop our own MQTT
+		-- echo so they don't double-render.
+		if sender_id == lobby.player_id then
+			return
+		end
+
 		local name = data.displayName or sender_id
-		local colour = (sender_id == lobby.player_id) and COLOUR_OWN or COLOUR_INCOMING
-		MPAPI.chat.addMessage(name .. ': ' .. data.message, colour)
+		MPAPI.chat.addMessage(name .. ': ' .. data.message, COLOUR_INCOMING)
 	end)
 end
 

compatibility/debugplus.lua

@@ -87,6 +87,11 @@ local function patch(dp_console, orig_render)
 				-- /say <message> → send as chat, don't let DP see it at all.
 				if M.send_fn then
 					M.send_fn(say_arg)
+				elseif MPAPI.connection_state.chat_enabled then
+					-- Chat is enabled server-side but we're not in a lobby
+					-- (send_fn only exists while lobby chat is active) --
+					-- mirrors chat.lua's make_not_enabled_cb branch.
+					M.addMessage(localize('k_chat_lobby_only'), COLOUR_SYSTEM)
 				else
 					M.addMessage(localize('k_chat_not_enabled'), COLOUR_SYSTEM)
 				end

localization/en-us.lua

@@ -73,6 +73,13 @@ return {
 			k_match_status_completed = 'Completed',
 			k_match_status_abandoned = 'Abandoned',
 			k_match_status_terminated = 'Terminated',
+			-- Delivery outcomes for a message the player already saw echoed.
+			-- The frame makes no claim about why or for how long: the reason
+			-- appended after it is the server's own self-contained sentence,
+			-- or k_chat_reason_unavailable when the server gave none.
+			k_chat_not_sent = '[MultiplayerAPI] Not sent',
+			k_chat_sent_as = '[MultiplayerAPI] Other players saw:',
+			k_chat_reason_unavailable = 'Something went wrong. Try again.',
 			-- Chat section in account overlay
 			k_chat_section_title = 'Chat',
 			b_chat_on = 'On',

networking/api_client/lobby.lua

@@ -96,13 +96,25 @@ function api_client:send_chat_message(jwt_token, code, message, callback)
 
 	self:_enqueue(function(status, body)
 		if status < 200 or status >= 300 then
+			-- Only a decoded { error = "..." } body is genuine player-facing
+			-- copy (chat.lua's k_chat_not_sent guard shows it verbatim). A
+			-- non-JSON or bare-status response -- a proxy error page, an
+			-- unexpected 5xx with no body -- carries no usable reason, so it's
+			-- TRANSPORT rather than SERVER: the caller falls back to its own
+			-- clean message instead of leaking this raw text to the player.
 			local ok, data = pcall(api_client.json_decode, body)
-			local emsg = (ok and data and data.error) or ('Server returned status ' .. tostring(status))
-			callback(MPAPI.make_error(MPAPI.ErrorKind.SERVER, emsg), nil)
+			if ok and data and data.error then
+				callback(MPAPI.make_error(MPAPI.ErrorKind.SERVER, data.error), nil)
+			else
+				callback(MPAPI.make_error(MPAPI.ErrorKind.TRANSPORT, 'Server returned status ' .. tostring(status)), nil)
+			end
 			return
 		end
 
-		callback(nil, { ok = true })
+		-- Pass the response body through: on a moderation rewrite it carries
+		-- publishText (what other players actually received).
+		local ok, data = pcall(api_client.json_decode, body)
+		callback(nil, (ok and type(data) == 'table') and data or { ok = true })
 	end, function(msg)
 		callback(MPAPI.make_error(MPAPI.ErrorKind.TRANSPORT, 'HTTP request failed: ' .. tostring(msg)), nil)
 	end)