README.md

@@ -845,10 +845,11 @@ the server to the client (never C2S) and use 3-digit string codes in the
 | `442` | ERR_NOTONCHANNEL    | Action on unjoined channel | `{"command":"442","to":"alice","params":["#general"],"body":["You're not on that channel"]}` |
 | `482` | ERR_CHANOPRIVSNEEDED | Non-op tries op action | `{"command":"482","to":"alice","params":["#general"],"body":["You're not channel operator"]}` |
 
-**Note:** Numeric replies are planned for full implementation. The current MVP
-returns standard HTTP error responses (4xx/5xx with JSON error bodies) instead
-of numeric replies for error conditions. Numeric replies in the message queue
-will be added post-MVP.
+**Note:** Numeric replies are now implemented. All IRC command responses
+(success and error) are delivered as numeric replies through the message queue.
+HTTP error codes are reserved for transport-level issues (auth failures,
+malformed requests, server errors). The `params` field in the message envelope
+carries IRC-style parameters (e.g., channel name, target nick).
 
 ### Channel Modes
 
@@ -1054,8 +1055,8 @@ reference with all required and optional fields.
 
 | Command   | Required Fields     | Optional      | Response Status |
 |-----------|---------------------|---------------|-----------------|
-| `PRIVMSG` | `to`, `body`        | `meta`        | 201 Created     |
-| `NOTICE`  | `to`, `body`        | `meta`        | 201 Created     |
+| `PRIVMSG` | `to`, `body`        | `meta`        | 200 OK          |
+| `NOTICE`  | `to`, `body`        | `meta`        | 200 OK          |
 | `JOIN`    | `to`                |               | 200 OK          |
 | `PART`    | `to`                | `body`        | 200 OK          |
 | `NICK`    | `body`              |               | 200 OK          |
@@ -1063,18 +1064,44 @@ reference with all required and optional fields.
 | `QUIT`    |                     | `body`        | 200 OK          |
 | `PING`    |                     |               | 200 OK          |
 
-**Errors (all commands):**
+All IRC commands return HTTP 200 OK. IRC-level success and error responses
+are delivered as **numeric replies** through the message queue (see
+[Numeric Replies](#numeric-replies) below). HTTP error codes (4xx/5xx) are
+reserved for transport-level problems: malformed JSON (400), missing/invalid
+auth tokens (401), and server errors (500).
+
+**HTTP errors (transport-level only):**
 
 | Status | Error | When |
 |--------|-------|------|
-| 400    | `invalid request` | Malformed JSON |
-| 400    | `to field required` | Missing `to` for commands that need it |
-| 400    | `body required` | Missing `body` for commands that need it |
-| 400    | `unknown command: X` | Unrecognized command |
+| 400    | `invalid request` | Malformed JSON or empty command |
 | 401    | `unauthorized` | Missing or invalid auth token |
-| 404    | `channel not found` | Target channel doesn't exist |
-| 404    | `user not found` | DM target nick doesn't exist |
-| 409    | `nick already in use` | NICK target is taken |
+| 500    | `internal error` | Server-side failure |
+
+**IRC numeric error replies (delivered via message queue):**
+
+| Numeric | Name | When |
+|---------|------|------|
+| 401     | ERR_NOSUCHNICK | DM target nick doesn't exist |
+| 403     | ERR_NOSUCHCHANNEL | Target channel doesn't exist or invalid name |
+| 421     | ERR_UNKNOWNCOMMAND | Unrecognized command |
+| 432     | ERR_ERRONEUSNICKNAME | Invalid nickname format |
+| 433     | ERR_NICKNAMEINUSE | NICK target is taken |
+| 442     | ERR_NOTONCHANNEL | Not a member of the target channel |
+| 461     | ERR_NEEDMOREPARAMS | Missing required fields (to, body) |
+
+**IRC numeric success replies (delivered via message queue):**
+
+| Numeric | Name | When |
+|---------|------|------|
+| 001     | RPL_WELCOME | Sent on session creation/login |
+| 331     | RPL_NOTOPIC | Channel has no topic (on JOIN) |
+| 332     | RPL_TOPIC | Channel topic (on JOIN, TOPIC set) |
+| 353     | RPL_NAMREPLY | Channel member list (on JOIN) |
+| 366     | RPL_ENDOFNAMES | End of NAMES list (on JOIN) |
+| 375     | RPL_MOTDSTART | Start of MOTD |
+| 372     | RPL_MOTD | MOTD line |
+| 376     | RPL_ENDOFMOTD | End of MOTD |
 
 ### GET /api/v1/history — Message History
 

internal/db/queries.go

@@ -35,6 +35,7 @@ type IRCMessage struct {
 	Command string          `json:"command"`
 	From    string          `json:"from,omitempty"`
 	To      string          `json:"to,omitempty"`
+	Params  json.RawMessage `json:"params,omitempty"`
 	Body    json.RawMessage `json:"body,omitempty"`
 	TS      string          `json:"ts"`
 	Meta    json.RawMessage `json:"meta,omitempty"`
@@ -491,12 +492,17 @@ func (database *Database) GetSessionChannelIDs(
 func (database *Database) InsertMessage(
 	ctx context.Context,
 	command, from, target string,
+	params json.RawMessage,
 	body json.RawMessage,
 	meta json.RawMessage,
 ) (int64, string, error) {
 	msgUUID := uuid.New().String()
 	now := time.Now().UTC()
 
+	if params == nil {
+		params = json.RawMessage("[]")
+	}
+
 	if body == nil {
 		body = json.RawMessage("[]")
 	}
@@ -508,10 +514,10 @@ func (database *Database) InsertMessage(
 	res, err := database.conn.ExecContext(ctx,
 		`INSERT INTO messages
 		 (uuid, command, msg_from, msg_to,
-		  body, meta, created_at)
-		 VALUES (?, ?, ?, ?, ?, ?, ?)`,
+		  params, body, meta, created_at)
+		 VALUES (?, ?, ?, ?, ?, ?, ?, ?)`,
 		msgUUID, command, from, target,
-		string(body), string(meta), now)
+		string(params), string(body), string(meta), now)
 	if err != nil {
 		return 0, "", fmt.Errorf(
 			"insert message: %w", err,
@@ -578,7 +584,7 @@ func (database *Database) PollMessages(
 	rows, err := database.conn.QueryContext(ctx,
 		`SELECT cq.id, m.uuid, m.command,
 		   m.msg_from, m.msg_to,
-		   m.body, m.meta, m.created_at
+		   m.params, m.body, m.meta, m.created_at
 		 FROM client_queues cq
 		 INNER JOIN messages m
 		   ON m.id = cq.message_id
@@ -642,7 +648,7 @@ func (database *Database) queryHistory(
 	if beforeID > 0 {
 		rows, err := database.conn.QueryContext(ctx,
 			`SELECT id, uuid, command, msg_from,
-			   msg_to, body, meta, created_at
+			   msg_to, params, body, meta, created_at
 			 FROM messages
 			 WHERE msg_to = ? AND id < ?
 			   AND command = 'PRIVMSG'
@@ -659,7 +665,7 @@ func (database *Database) queryHistory(
 
 	rows, err := database.conn.QueryContext(ctx,
 		`SELECT id, uuid, command, msg_from,
-		   msg_to, body, meta, created_at
+		   msg_to, params, body, meta, created_at
 		 FROM messages
 		 WHERE msg_to = ?
 		   AND command = 'PRIVMSG'
@@ -684,16 +690,16 @@ func scanMessages(
 
 	for rows.Next() {
 		var (
-			msg        IRCMessage
-			qID        int64
-			body, meta string
-			createdAt  time.Time
+			msg                IRCMessage
+			qID                int64
+			params, body, meta string
+			createdAt          time.Time
 		)
 
 		err := rows.Scan(
 			&qID, &msg.ID, &msg.Command,
 			&msg.From, &msg.To,
-			&body, &meta, &createdAt,
+			&params, &body, &meta, &createdAt,
 		)
 		if err != nil {
 			return nil, fallbackQID, fmt.Errorf(
@@ -701,6 +707,10 @@ func scanMessages(
 			)
 		}
 
+		if params != "" && params != "[]" {
+			msg.Params = json.RawMessage(params)
+		}
+
 		msg.Body = json.RawMessage(body)
 		msg.Meta = json.RawMessage(meta)
 		msg.TS = createdAt.Format(time.RFC3339Nano)

internal/db/queries_test.go

@@ -383,7 +383,7 @@ func TestInsertMessage(t *testing.T) {
 	body := json.RawMessage(`["hello"]`)
 
 	dbID, msgUUID, err := database.InsertMessage(
-		ctx, "PRIVMSG", "poller", "#test", body, nil,
+		ctx, "PRIVMSG", "poller", "#test", nil, body, nil,
 	)
 	if err != nil {
 		t.Fatal(err)
@@ -417,7 +417,7 @@ func TestPollMessages(t *testing.T) {
 	body := json.RawMessage(`["hello"]`)
 
 	dbID, _, err := database.InsertMessage(
-		ctx, "PRIVMSG", "poller", "#test", body, nil,
+		ctx, "PRIVMSG", "poller", "#test", nil, body, nil,
 	)
 	if err != nil {
 		t.Fatal(err)
@@ -475,7 +475,7 @@ func TestGetHistory(t *testing.T) {
 	for range msgCount {
 		_, _, err := database.InsertMessage(
 			ctx, "PRIVMSG", "user", "#hist",
-			json.RawMessage(`["msg"]`), nil,
+			nil, json.RawMessage(`["msg"]`), nil,
 		)
 		if err != nil {
 			t.Fatal(err)
@@ -627,7 +627,7 @@ func TestEnqueueToClient(t *testing.T) {
 	body := json.RawMessage(`["test"]`)
 
 	dbID, _, err := database.InsertMessage(
-		ctx, "PRIVMSG", "sender", "#ch", body, nil,
+		ctx, "PRIVMSG", "sender", "#ch", nil, body, nil,
 	)
 	if err != nil {
 		t.Fatal(err)

internal/db/schema/001_initial.sql

@@ -50,6 +50,7 @@ CREATE TABLE IF NOT EXISTS messages (
     command TEXT NOT NULL DEFAULT 'PRIVMSG',
     msg_from TEXT NOT NULL DEFAULT '',
     msg_to TEXT NOT NULL DEFAULT '',
+    params TEXT NOT NULL DEFAULT '[]',
     body TEXT NOT NULL DEFAULT '[]',
     meta TEXT NOT NULL DEFAULT '{}',
     created_at DATETIME DEFAULT CURRENT_TIMESTAMP

internal/handlers/api.go

@@ -91,7 +91,7 @@ func (hdlr *Handlers) fanOut(
 	sessionIDs []int64,
 ) (string, error) {
 	dbID, msgUUID, err := hdlr.params.Database.InsertMessage(
-		request.Context(), command, from, target, body, nil,
+		request.Context(), command, from, target, nil, body, nil,
 	)
 	if err != nil {
 		return "", fmt.Errorf("insert message: %w", err)
@@ -185,7 +185,7 @@ func (hdlr *Handlers) handleCreateSession(
 		return
 	}
 
-	hdlr.deliverMOTD(request, clientID, sessionID)
+	hdlr.deliverMOTD(request, clientID, sessionID, payload.Nick)
 
 	hdlr.respondJSON(writer, request, map[string]any{
 		"id":    sessionID,
@@ -219,49 +219,76 @@ func (hdlr *Handlers) handleCreateSessionError(
 	)
 }
 
+// deliverWelcome sends the RPL_WELCOME (001) numeric to a
+// new client.
+func (hdlr *Handlers) deliverWelcome(
+	request *http.Request,
+	clientID int64,
+	nick string,
+) {
+	ctx := request.Context()
+
+	hdlr.enqueueNumeric(
+		ctx, clientID, "001", nick, nil,
+		"Welcome to the network, "+nick,
+	)
+}
+
 // deliverMOTD sends the MOTD as IRC numeric messages to a
 // new client.
 func (hdlr *Handlers) deliverMOTD(
 	request *http.Request,
 	clientID, sessionID int64,
+	nick string,
 ) {
 	motd := hdlr.params.Config.MOTD
-	serverName := hdlr.params.Config.ServerName
-
-	if serverName == "" {
-		serverName = "neoirc"
-	}
-
-	if motd == "" {
-		return
-	}
+	srvName := hdlr.serverName()
 
 	ctx := request.Context()
 
+	hdlr.deliverWelcome(request, clientID, nick)
+
+	if motd == "" {
+		hdlr.broker.Notify(sessionID)
+
+		return
+	}
+
 	hdlr.enqueueNumeric(
-		ctx, clientID, "375", serverName,
-		"- "+serverName+" Message of the Day -",
+		ctx, clientID, "375", nick, nil,
+		"- "+srvName+" Message of the Day -",
 	)
 
 	for line := range strings.SplitSeq(motd, "\n") {
 		hdlr.enqueueNumeric(
-			ctx, clientID, "372", serverName,
+			ctx, clientID, "372", nick, nil,
 			"- "+line,
 		)
 	}
 
 	hdlr.enqueueNumeric(
-		ctx, clientID, "376", serverName,
+		ctx, clientID, "376", nick, nil,
 		"End of /MOTD command.",
 	)
 
 	hdlr.broker.Notify(sessionID)
 }
 
+func (hdlr *Handlers) serverName() string {
+	name := hdlr.params.Config.ServerName
+	if name == "" {
+		return "neoirc"
+	}
+
+	return name
+}
+
 func (hdlr *Handlers) enqueueNumeric(
 	ctx context.Context,
 	clientID int64,
-	command, serverName, text string,
+	command, nick string,
+	params []string,
+	text string,
 ) {
 	body, err := json.Marshal([]string{text})
 	if err != nil {
@@ -272,9 +299,22 @@ func (hdlr *Handlers) enqueueNumeric(
 		return
 	}
 
+	var paramsJSON json.RawMessage
+
+	if len(params) > 0 {
+		paramsJSON, err = json.Marshal(params)
+		if err != nil {
+			hdlr.log.Error(
+				"marshal numeric params", "error", err,
+			)
+
+			return
+		}
+	}
+
 	dbID, _, insertErr := hdlr.params.Database.InsertMessage(
-		ctx, command, serverName, "",
-		json.RawMessage(body), nil,
+		ctx, command, hdlr.serverName(), nick,
+		paramsJSON, json.RawMessage(body), nil,
 	)
 	if insertErr != nil {
 		hdlr.log.Error(
@@ -532,7 +572,7 @@ func (hdlr *Handlers) HandleSendCommand() http.HandlerFunc {
 			writer, request.Body, hdlr.maxBodySize(),
 		)
 
-		sessionID, _, nick, ok :=
+		sessionID, clientID, nick, ok :=
 			hdlr.requireAuth(writer, request)
 		if !ok {
 			return
@@ -582,7 +622,8 @@ func (hdlr *Handlers) HandleSendCommand() http.HandlerFunc {
 		}
 
 		hdlr.dispatchCommand(
-			writer, request, sessionID, nick,
+			writer, request,
+			sessionID, clientID, nick,
 			payload.Command, payload.To,
 			payload.Body, bodyLines,
 		)
@@ -592,7 +633,7 @@ func (hdlr *Handlers) HandleSendCommand() http.HandlerFunc {
 func (hdlr *Handlers) dispatchCommand(
 	writer http.ResponseWriter,
 	request *http.Request,
-	sessionID int64,
+	sessionID, clientID int64,
 	nick, command, target string,
 	body json.RawMessage,
 	bodyLines func() []string,
@@ -600,24 +641,30 @@ func (hdlr *Handlers) dispatchCommand(
 	switch command {
 	case cmdPrivmsg, "NOTICE":
 		hdlr.handlePrivmsg(
-			writer, request, sessionID, nick,
+			writer, request,
+			sessionID, clientID, nick,
 			command, target, body, bodyLines,
 		)
 	case "JOIN":
 		hdlr.handleJoin(
-			writer, request, sessionID, nick, target,
+			writer, request,
+			sessionID, clientID, nick, target,
 		)
 	case "PART":
 		hdlr.handlePart(
-			writer, request, sessionID, nick, target, body,
+			writer, request,
+			sessionID, clientID, nick, target, body,
 		)
 	case "NICK":
 		hdlr.handleNick(
-			writer, request, sessionID, nick, bodyLines,
+			writer, request,
+			sessionID, clientID, nick, bodyLines,
 		)
 	case "TOPIC":
 		hdlr.handleTopic(
-			writer, request, nick, target, body, bodyLines,
+			writer, request,
+			sessionID, clientID, nick,
+			target, body, bodyLines,
 		)
 	case "QUIT":
 		hdlr.handleQuit(
@@ -627,50 +674,63 @@ func (hdlr *Handlers) dispatchCommand(
 		hdlr.respondJSON(writer, request,
 			map[string]string{
 				"command": "PONG",
-				"from":    hdlr.params.Config.ServerName,
+				"from":    hdlr.serverName(),
 			},
 			http.StatusOK)
 	default:
-		hdlr.respondError(
-			writer, request,
-			"unknown command: "+command,
-			http.StatusBadRequest,
+		hdlr.enqueueNumeric(
+			request.Context(), clientID,
+			"421", nick, []string{command},
+			"Unknown command",
 		)
+		hdlr.broker.Notify(sessionID)
+		hdlr.respondJSON(writer, request,
+			map[string]string{"status": "error"},
+			http.StatusOK)
 	}
 }
 
 func (hdlr *Handlers) handlePrivmsg(
 	writer http.ResponseWriter,
 	request *http.Request,
-	sessionID int64,
+	sessionID, clientID int64,
 	nick, command, target string,
 	body json.RawMessage,
 	bodyLines func() []string,
 ) {
 	if target == "" {
-		hdlr.respondError(
-			writer, request,
-			"to field required",
-			http.StatusBadRequest,
+		hdlr.enqueueNumeric(
+			request.Context(), clientID,
+			"461", nick, []string{command},
+			"Not enough parameters",
 		)
+		hdlr.broker.Notify(sessionID)
+		hdlr.respondJSON(writer, request,
+			map[string]string{"status": "error"},
+			http.StatusOK)
 
 		return
 	}
 
 	lines := bodyLines()
 	if len(lines) == 0 {
-		hdlr.respondError(
-			writer, request,
-			"body required",
-			http.StatusBadRequest,
+		hdlr.enqueueNumeric(
+			request.Context(), clientID,
+			"461", nick, []string{command},
+			"Not enough parameters",
 		)
+		hdlr.broker.Notify(sessionID)
+		hdlr.respondJSON(writer, request,
+			map[string]string{"status": "error"},
+			http.StatusOK)
 
 		return
 	}
 
 	if strings.HasPrefix(target, "#") {
 		hdlr.handleChannelMsg(
-			writer, request, sessionID, nick,
+			writer, request,
+			sessionID, clientID, nick,
 			command, target, body,
 		)
 
@@ -678,15 +738,36 @@ func (hdlr *Handlers) handlePrivmsg(
 	}
 
 	hdlr.handleDirectMsg(
-		writer, request, sessionID, nick,
+		writer, request,
+		sessionID, clientID, nick,
 		command, target, body,
 	)
 }
 
+// respondIRCError enqueues a numeric error reply, notifies
+// the broker, and sends HTTP 200 with {"status":"error"}.
+func (hdlr *Handlers) respondIRCError(
+	writer http.ResponseWriter,
+	request *http.Request,
+	clientID, sessionID int64,
+	numeric, nick string,
+	params []string,
+	text string,
+) {
+	hdlr.enqueueNumeric(
+		request.Context(), clientID,
+		numeric, nick, params, text,
+	)
+	hdlr.broker.Notify(sessionID)
+	hdlr.respondJSON(writer, request,
+		map[string]string{"status": "error"},
+		http.StatusOK)
+}
+
 func (hdlr *Handlers) handleChannelMsg(
 	writer http.ResponseWriter,
 	request *http.Request,
-	sessionID int64,
+	sessionID, clientID int64,
 	nick, command, target string,
 	body json.RawMessage,
 ) {
@@ -694,10 +775,10 @@ func (hdlr *Handlers) handleChannelMsg(
 		request.Context(), target,
 	)
 	if err != nil {
-		hdlr.respondError(
-			writer, request,
-			"channel not found",
-			http.StatusNotFound,
+		hdlr.respondIRCError(
+			writer, request, clientID, sessionID,
+			"403", nick, []string{target},
+			"No such channel",
 		)
 
 		return
@@ -720,15 +801,27 @@ func (hdlr *Handlers) handleChannelMsg(
 	}
 
 	if !isMember {
-		hdlr.respondError(
-			writer, request,
-			"not a member of this channel",
-			http.StatusForbidden,
+		hdlr.respondIRCError(
+			writer, request, clientID, sessionID,
+			"442", nick, []string{target},
+			"You're not on that channel",
 		)
 
 		return
 	}
 
+	hdlr.sendChannelMsg(
+		writer, request, command, nick, target, body, chID,
+	)
+}
+
+func (hdlr *Handlers) sendChannelMsg(
+	writer http.ResponseWriter,
+	request *http.Request,
+	command, nick, target string,
+	body json.RawMessage,
+	chID int64,
+) {
 	memberIDs, err := hdlr.params.Database.GetChannelMemberIDs(
 		request.Context(), chID,
 	)
@@ -761,13 +854,13 @@ func (hdlr *Handlers) handleChannelMsg(
 
 	hdlr.respondJSON(writer, request,
 		map[string]string{"id": msgUUID, "status": "sent"},
-		http.StatusCreated)
+		http.StatusOK)
 }
 
 func (hdlr *Handlers) handleDirectMsg(
 	writer http.ResponseWriter,
 	request *http.Request,
-	sessionID int64,
+	sessionID, clientID int64,
 	nick, command, target string,
 	body json.RawMessage,
 ) {
@@ -775,11 +868,15 @@ func (hdlr *Handlers) handleDirectMsg(
 		request.Context(), target,
 	)
 	if err != nil {
-		hdlr.respondError(
-			writer, request,
-			"user not found",
-			http.StatusNotFound,
+		hdlr.enqueueNumeric(
+			request.Context(), clientID,
+			"401", nick, []string{target},
+			"No such nick/channel",
 		)
+		hdlr.broker.Notify(sessionID)
+		hdlr.respondJSON(writer, request,
+			map[string]string{"status": "error"},
+			http.StatusOK)
 
 		return
 	}
@@ -805,20 +902,20 @@ func (hdlr *Handlers) handleDirectMsg(
 
 	hdlr.respondJSON(writer, request,
 		map[string]string{"id": msgUUID, "status": "sent"},
-		http.StatusCreated)
+		http.StatusOK)
 }
 
 func (hdlr *Handlers) handleJoin(
 	writer http.ResponseWriter,
 	request *http.Request,
-	sessionID int64,
+	sessionID, clientID int64,
 	nick, target string,
 ) {
 	if target == "" {
-		hdlr.respondError(
-			writer, request,
-			"to field required",
-			http.StatusBadRequest,
+		hdlr.respondIRCError(
+			writer, request, clientID, sessionID,
+			"461", nick, []string{"JOIN"},
+			"Not enough parameters",
 		)
 
 		return
@@ -830,15 +927,27 @@ func (hdlr *Handlers) handleJoin(
 	}
 
 	if !validChannelRe.MatchString(channel) {
-		hdlr.respondError(
-			writer, request,
-			"invalid channel name",
-			http.StatusBadRequest,
+		hdlr.respondIRCError(
+			writer, request, clientID, sessionID,
+			"403", nick, []string{channel},
+			"No such channel",
 		)
 
 		return
 	}
 
+	hdlr.executeJoin(
+		writer, request,
+		sessionID, clientID, nick, channel,
+	)
+}
+
+func (hdlr *Handlers) executeJoin(
+	writer http.ResponseWriter,
+	request *http.Request,
+	sessionID, clientID int64,
+	nick, channel string,
+) {
 	chID, err := hdlr.params.Database.GetOrCreateChannel(
 		request.Context(), channel,
 	)
@@ -879,6 +988,10 @@ func (hdlr *Handlers) handleJoin(
 		request, "JOIN", nick, channel, nil, memberIDs,
 	)
 
+	hdlr.deliverJoinNumerics(
+		request, clientID, sessionID, nick, channel, chID,
+	)
+
 	hdlr.respondJSON(writer, request,
 		map[string]string{
 			"status":  "joined",
@@ -887,19 +1000,96 @@ func (hdlr *Handlers) handleJoin(
 		http.StatusOK)
 }
 
+// deliverJoinNumerics sends RPL_TOPIC/RPL_NOTOPIC,
+// RPL_NAMREPLY, and RPL_ENDOFNAMES to the joining client.
+func (hdlr *Handlers) deliverJoinNumerics(
+	request *http.Request,
+	clientID, sessionID int64,
+	nick, channel string,
+	chID int64,
+) {
+	ctx := request.Context()
+
+	chInfo, err := hdlr.params.Database.GetChannelByName(
+		ctx, channel,
+	)
+	if err == nil {
+		_ = chInfo // chInfo is the ID; topic comes from DB.
+	}
+
+	// Get topic from channel info.
+	channels, listErr := hdlr.params.Database.ListChannels(
+		ctx, sessionID,
+	)
+
+	topic := ""
+
+	if listErr == nil {
+		for _, ch := range channels {
+			if ch.Name == channel {
+				topic = ch.Topic
+
+				break
+			}
+		}
+	}
+
+	if topic != "" {
+		hdlr.enqueueNumeric(
+			ctx, clientID, "332", nick,
+			[]string{channel}, topic,
+		)
+	} else {
+		hdlr.enqueueNumeric(
+			ctx, clientID, "331", nick,
+			[]string{channel}, "No topic is set",
+		)
+	}
+
+	// Get member list for NAMES reply.
+	members, memErr := hdlr.params.Database.ChannelMembers(
+		ctx, chID,
+	)
+
+	if memErr == nil && len(members) > 0 {
+		nicks := make([]string, 0, len(members))
+
+		for _, mem := range members {
+			nicks = append(nicks, mem.Nick)
+		}
+
+		hdlr.enqueueNumeric(
+			ctx, clientID, "353", nick,
+			[]string{"=", channel},
+			strings.Join(nicks, " "),
+		)
+	}
+
+	hdlr.enqueueNumeric(
+		ctx, clientID, "366", nick,
+		[]string{channel}, "End of /NAMES list",
+	)
+
+	hdlr.broker.Notify(sessionID)
+}
+
 func (hdlr *Handlers) handlePart(
 	writer http.ResponseWriter,
 	request *http.Request,
-	sessionID int64,
+	sessionID, clientID int64,
 	nick, target string,
 	body json.RawMessage,
 ) {
 	if target == "" {
-		hdlr.respondError(
-			writer, request,
-			"to field required",
-			http.StatusBadRequest,
+		hdlr.enqueueNumeric(
+			request.Context(), clientID,
+			"461", nick, []string{"PART"},
+			"Not enough parameters",
 		)
+		hdlr.broker.Notify(sessionID)
+		hdlr.respondJSON(writer, request,
+			map[string]string{"status": "error"},
+			http.StatusOK)
 
 		return
 	}
@@ -913,11 +1103,15 @@ func (hdlr *Handlers) handlePart(
 		request.Context(), channel,
 	)
 	if err != nil {
-		hdlr.respondError(
-			writer, request,
-			"channel not found",
-			http.StatusNotFound,
+		hdlr.enqueueNumeric(
+			request.Context(), clientID,
+			"403", nick, []string{channel},
+			"No such channel",
 		)
+		hdlr.broker.Notify(sessionID)
+		hdlr.respondJSON(writer, request,
+			map[string]string{"status": "error"},
+			http.StatusOK)
 
 		return
 	}
@@ -961,16 +1155,16 @@ func (hdlr *Handlers) handlePart(
 func (hdlr *Handlers) handleNick(
 	writer http.ResponseWriter,
 	request *http.Request,
-	sessionID int64,
+	sessionID, clientID int64,
 	nick string,
 	bodyLines func() []string,
 ) {
 	lines := bodyLines()
 	if len(lines) == 0 {
-		hdlr.respondError(
-			writer, request,
-			"body required (new nick)",
-			http.StatusBadRequest,
+		hdlr.respondIRCError(
+			writer, request, clientID, sessionID,
+			"461", nick, []string{"NICK"},
+			"Not enough parameters",
 		)
 
 		return
@@ -979,10 +1173,10 @@ func (hdlr *Handlers) handleNick(
 	newNick := strings.TrimSpace(lines[0])
 
 	if !validNickRe.MatchString(newNick) {
-		hdlr.respondError(
-			writer, request,
-			"invalid nick",
-			http.StatusBadRequest,
+		hdlr.respondIRCError(
+			writer, request, clientID, sessionID,
+			"432", nick, []string{newNick},
+			"Erroneous nickname",
 		)
 
 		return
@@ -998,15 +1192,27 @@ func (hdlr *Handlers) handleNick(
 		return
 	}
 
+	hdlr.executeNickChange(
+		writer, request,
+		sessionID, clientID, nick, newNick,
+	)
+}
+
+func (hdlr *Handlers) executeNickChange(
+	writer http.ResponseWriter,
+	request *http.Request,
+	sessionID, clientID int64,
+	nick, newNick string,
+) {
 	err := hdlr.params.Database.ChangeNick(
 		request.Context(), sessionID, newNick,
 	)
 	if err != nil {
 		if strings.Contains(err.Error(), "UNIQUE") {
-			hdlr.respondError(
-				writer, request,
-				"nick already in use",
-				http.StatusConflict,
+			hdlr.respondIRCError(
+				writer, request, clientID, sessionID,
+				"433", nick, []string{newNick},
+				"Nickname is already in use",
 			)
 
 			return
@@ -1056,7 +1262,7 @@ func (hdlr *Handlers) broadcastNick(
 
 	dbID, _, _ := hdlr.params.Database.InsertMessage(
 		request.Context(), "NICK", oldNick, "",
-		json.RawMessage(nickBody), nil,
+		nil, json.RawMessage(nickBody), nil,
 	)
 
 	_ = hdlr.params.Database.EnqueueToSession(
@@ -1088,15 +1294,16 @@ func (hdlr *Handlers) broadcastNick(
 func (hdlr *Handlers) handleTopic(
 	writer http.ResponseWriter,
 	request *http.Request,
+	sessionID, clientID int64,
 	nick, target string,
 	body json.RawMessage,
 	bodyLines func() []string,
 ) {
 	if target == "" {
-		hdlr.respondError(
-			writer, request,
-			"to field required",
-			http.StatusBadRequest,
+		hdlr.respondIRCError(
+			writer, request, clientID, sessionID,
+			"461", nick, []string{"TOPIC"},
+			"Not enough parameters",
 		)
 
 		return
@@ -1104,46 +1311,60 @@ func (hdlr *Handlers) handleTopic(
 
 	lines := bodyLines()
 	if len(lines) == 0 {
-		hdlr.respondError(
-			writer, request,
-			"body required (topic text)",
-			http.StatusBadRequest,
+		hdlr.respondIRCError(
+			writer, request, clientID, sessionID,
+			"461", nick, []string{"TOPIC"},
+			"Not enough parameters",
 		)
 
 		return
 	}
 
-	topic := strings.Join(lines, " ")
-
 	channel := target
 	if !strings.HasPrefix(channel, "#") {
 		channel = "#" + channel
 	}
 
-	err := hdlr.params.Database.SetTopic(
-		request.Context(), channel, topic,
+	chID, err := hdlr.params.Database.GetChannelByName(
+		request.Context(), channel,
 	)
 	if err != nil {
-		hdlr.log.Error(
-			"set topic failed", "error", err,
-		)
-		hdlr.respondError(
-			writer, request,
-			"internal error",
-			http.StatusInternalServerError,
+		hdlr.respondIRCError(
+			writer, request, clientID, sessionID,
+			"403", nick, []string{channel},
+			"No such channel",
 		)
 
 		return
 	}
 
-	chID, err := hdlr.params.Database.GetChannelByName(
-		request.Context(), channel,
+	hdlr.executeTopic(
+		writer, request,
+		sessionID, clientID, nick,
+		channel, strings.Join(lines, " "),
+		body, chID,
 	)
-	if err != nil {
+}
+
+func (hdlr *Handlers) executeTopic(
+	writer http.ResponseWriter,
+	request *http.Request,
+	sessionID, clientID int64,
+	nick, channel, topic string,
+	body json.RawMessage,
+	chID int64,
+) {
+	setErr := hdlr.params.Database.SetTopic(
+		request.Context(), channel, topic,
+	)
+	if setErr != nil {
+		hdlr.log.Error(
+			"set topic failed", "error", setErr,
+		)
 		hdlr.respondError(
 			writer, request,
-			"channel not found",
-			http.StatusNotFound,
+			"internal error",
+			http.StatusInternalServerError,
 		)
 
 		return
@@ -1157,6 +1378,12 @@ func (hdlr *Handlers) handleTopic(
 		request, "TOPIC", nick, channel, body, memberIDs,
 	)
 
+	hdlr.enqueueNumeric(
+		request.Context(), clientID,
+		"332", nick, []string{channel}, topic,
+	)
+	hdlr.broker.Notify(sessionID)
+
 	hdlr.respondJSON(writer, request,
 		map[string]string{
 			"status": "ok", "topic": topic,
@@ -1182,7 +1409,8 @@ func (hdlr *Handlers) handleQuit(
 
 	if len(channels) > 0 {
 		dbID, _, _ = hdlr.params.Database.InsertMessage(
-			request.Context(), "QUIT", nick, "", body, nil,
+			request.Context(), "QUIT", nick, "",
+			nil, body, nil,
 		)
 	}
 
@@ -1431,7 +1659,8 @@ func (hdlr *Handlers) cleanupUser(
 
 	if len(channels) > 0 {
 		quitDBID, _, _ = hdlr.params.Database.InsertMessage(
-			ctx, "QUIT", nick, "", nil, nil,
+			ctx, "QUIT", nick, "",
+			nil, nil, nil,
 		)
 	}
 

internal/handlers/api_test.go

@@ -462,6 +462,19 @@ func findMessage(
 	return false
 }
 
+func findNumeric(
+	msgs []map[string]any,
+	numeric string,
+) bool {
+	for _, msg := range msgs {
+		if msg[commandKey] == numeric {
+			return true
+		}
+	}
+
+	return false
+}
+
 // --- Tests ---
 
 func TestCreateSessionValid(t *testing.T) {
@@ -473,6 +486,47 @@ func TestCreateSessionValid(t *testing.T) {
 	}
 }
 
+func TestWelcomeNumeric(t *testing.T) {
+	tserver := newTestServer(t)
+	token := tserver.createSession("welcomer")
+
+	msgs, _ := tserver.pollMessages(token, 0)
+
+	if !findNumeric(msgs, "001") {
+		t.Fatalf(
+			"expected RPL_WELCOME (001), got %v",
+			msgs,
+		)
+	}
+}
+
+func TestJoinNumerics(t *testing.T) {
+	tserver := newTestServer(t)
+	token := tserver.createSession("jnumtest")
+
+	_, lastID := tserver.pollMessages(token, 0)
+
+	tserver.sendCommand(token, map[string]any{
+		commandKey: joinCmd, toKey: "#numtest",
+	})
+
+	msgs, _ := tserver.pollMessages(token, lastID)
+
+	if !findNumeric(msgs, "353") {
+		t.Fatalf(
+			"expected RPL_NAMREPLY (353), got %v",
+			msgs,
+		)
+	}
+
+	if !findNumeric(msgs, "366") {
+		t.Fatalf(
+			"expected RPL_ENDOFNAMES (366), got %v",
+			msgs,
+		)
+	}
+}
+
 func TestCreateSessionDuplicate(t *testing.T) {
 	tserver := newTestServer(t)
 	tserver.createSession("alice")
@@ -668,11 +722,23 @@ func TestJoinMissingTo(t *testing.T) {
 	tserver := newTestServer(t)
 	token := tserver.createSession("joiner3")
 
+	// Drain initial MOTD/welcome numerics.
+	_, lastID := tserver.pollMessages(token, 0)
+
 	status, _ := tserver.sendCommand(
 		token, map[string]any{commandKey: joinCmd},
 	)
-	if status != http.StatusBadRequest {
-		t.Fatalf("expected 400, got %d", status)
+	if status != http.StatusOK {
+		t.Fatalf("expected 200, got %d", status)
+	}
+
+	msgs, _ := tserver.pollMessages(token, lastID)
+
+	if !findNumeric(msgs, "461") {
+		t.Fatalf(
+			"expected ERR_NEEDMOREPARAMS (461), got %v",
+			msgs,
+		)
 	}
 }
 
@@ -699,9 +765,9 @@ func TestChannelMessage(t *testing.T) {
 			bodyKey:    []string{"hello world"},
 		},
 	)
-	if status != http.StatusCreated {
+	if status != http.StatusOK {
 		t.Fatalf(
-			"expected 201, got %d: %v", status, result,
+			"expected 200, got %d: %v", status, result,
 		)
 	}
 
@@ -728,11 +794,22 @@ func TestMessageMissingBody(t *testing.T) {
 		commandKey: joinCmd, toKey: "#test",
 	})
 
+	_, lastID := tserver.pollMessages(token, 0)
+
 	status, _ := tserver.sendCommand(token, map[string]any{
 		commandKey: privmsgCmd, toKey: "#test",
 	})
-	if status != http.StatusBadRequest {
-		t.Fatalf("expected 400, got %d", status)
+	if status != http.StatusOK {
+		t.Fatalf("expected 200, got %d", status)
+	}
+
+	msgs, _ := tserver.pollMessages(token, lastID)
+
+	if !findNumeric(msgs, "461") {
+		t.Fatalf(
+			"expected ERR_NEEDMOREPARAMS (461), got %v",
+			msgs,
+		)
 	}
 }
 
@@ -740,12 +817,23 @@ func TestMessageMissingTo(t *testing.T) {
 	tserver := newTestServer(t)
 	token := tserver.createSession("noto")
 
+	_, lastID := tserver.pollMessages(token, 0)
+
 	status, _ := tserver.sendCommand(token, map[string]any{
 		commandKey: privmsgCmd,
 		bodyKey:    []string{"hello"},
 	})
-	if status != http.StatusBadRequest {
-		t.Fatalf("expected 400, got %d", status)
+	if status != http.StatusOK {
+		t.Fatalf("expected 200, got %d", status)
+	}
+
+	msgs, _ := tserver.pollMessages(token, lastID)
+
+	if !findNumeric(msgs, "461") {
+		t.Fatalf(
+			"expected ERR_NEEDMOREPARAMS (461), got %v",
+			msgs,
+		)
 	}
 }
 
@@ -759,6 +847,8 @@ func TestNonMemberCannotSend(t *testing.T) {
 		commandKey: joinCmd, toKey: "#private",
 	})
 
+	_, lastID := tserver.pollMessages(aliceToken, 0)
+
 	// Alice tries to send without joining.
 	status, _ := tserver.sendCommand(
 		aliceToken,
@@ -768,8 +858,17 @@ func TestNonMemberCannotSend(t *testing.T) {
 			bodyKey:    []string{"sneaky"},
 		},
 	)
-	if status != http.StatusForbidden {
-		t.Fatalf("expected 403, got %d", status)
+	if status != http.StatusOK {
+		t.Fatalf("expected 200, got %d", status)
+	}
+
+	msgs, _ := tserver.pollMessages(aliceToken, lastID)
+
+	if !findNumeric(msgs, "442") {
+		t.Fatalf(
+			"expected ERR_NOTONCHANNEL (442), got %v",
+			msgs,
+		)
 	}
 }
 
@@ -786,9 +885,9 @@ func TestDirectMessage(t *testing.T) {
 			bodyKey:    []string{"hey bob"},
 		},
 	)
-	if status != http.StatusCreated {
+	if status != http.StatusOK {
 		t.Fatalf(
-			"expected 201, got %d: %v", status, result,
+			"expected 200, got %d: %v", status, result,
 		)
 	}
 
@@ -818,13 +917,24 @@ func TestDMToNonexistentUser(t *testing.T) {
 	tserver := newTestServer(t)
 	token := tserver.createSession("dmsender")
 
+	_, lastID := tserver.pollMessages(token, 0)
+
 	status, _ := tserver.sendCommand(token, map[string]any{
 		commandKey: privmsgCmd,
 		toKey:      "nobody",
 		bodyKey:    []string{"hello?"},
 	})
-	if status != http.StatusNotFound {
-		t.Fatalf("expected 404, got %d", status)
+	if status != http.StatusOK {
+		t.Fatalf("expected 200, got %d", status)
+	}
+
+	msgs, _ := tserver.pollMessages(token, lastID)
+
+	if !findNumeric(msgs, "401") {
+		t.Fatalf(
+			"expected ERR_NOSUCHNICK (401), got %v",
+			msgs,
+		)
 	}
 }
 
@@ -871,12 +981,23 @@ func TestNickCollision(t *testing.T) {
 
 	tserver.createSession("taken_nick")
 
+	_, lastID := tserver.pollMessages(token, 0)
+
 	status, _ := tserver.sendCommand(token, map[string]any{
 		commandKey: "NICK",
 		bodyKey:    []string{"taken_nick"},
 	})
-	if status != http.StatusConflict {
-		t.Fatalf("expected 409, got %d", status)
+	if status != http.StatusOK {
+		t.Fatalf("expected 200, got %d", status)
+	}
+
+	msgs, _ := tserver.pollMessages(token, lastID)
+
+	if !findNumeric(msgs, "433") {
+		t.Fatalf(
+			"expected ERR_NICKNAMEINUSE (433), got %v",
+			msgs,
+		)
 	}
 }
 
@@ -884,12 +1005,23 @@ func TestNickInvalid(t *testing.T) {
 	tserver := newTestServer(t)
 	token := tserver.createSession("nickval")
 
+	_, lastID := tserver.pollMessages(token, 0)
+
 	status, _ := tserver.sendCommand(token, map[string]any{
 		commandKey: "NICK",
 		bodyKey:    []string{"bad nick!"},
 	})
-	if status != http.StatusBadRequest {
-		t.Fatalf("expected 400, got %d", status)
+	if status != http.StatusOK {
+		t.Fatalf("expected 200, got %d", status)
+	}
+
+	msgs, _ := tserver.pollMessages(token, lastID)
+
+	if !findNumeric(msgs, "432") {
+		t.Fatalf(
+			"expected ERR_ERRONEUSNICKNAME (432), got %v",
+			msgs,
+		)
 	}
 }
 
@@ -897,11 +1029,22 @@ func TestNickEmptyBody(t *testing.T) {
 	tserver := newTestServer(t)
 	token := tserver.createSession("nicknobody")
 
+	_, lastID := tserver.pollMessages(token, 0)
+
 	status, _ := tserver.sendCommand(
 		token, map[string]any{commandKey: "NICK"},
 	)
-	if status != http.StatusBadRequest {
-		t.Fatalf("expected 400, got %d", status)
+	if status != http.StatusOK {
+		t.Fatalf("expected 200, got %d", status)
+	}
+
+	msgs, _ := tserver.pollMessages(token, lastID)
+
+	if !findNumeric(msgs, "461") {
+		t.Fatalf(
+			"expected ERR_NEEDMOREPARAMS (461), got %v",
+			msgs,
+		)
 	}
 }
 
@@ -938,12 +1081,23 @@ func TestTopicMissingTo(t *testing.T) {
 	tserver := newTestServer(t)
 	token := tserver.createSession("topicnoto")
 
+	_, lastID := tserver.pollMessages(token, 0)
+
 	status, _ := tserver.sendCommand(token, map[string]any{
 		commandKey: "TOPIC",
 		bodyKey:    []string{"topic"},
 	})
-	if status != http.StatusBadRequest {
-		t.Fatalf("expected 400, got %d", status)
+	if status != http.StatusOK {
+		t.Fatalf("expected 200, got %d", status)
+	}
+
+	msgs, _ := tserver.pollMessages(token, lastID)
+
+	if !findNumeric(msgs, "461") {
+		t.Fatalf(
+			"expected ERR_NEEDMOREPARAMS (461), got %v",
+			msgs,
+		)
 	}
 }
 
@@ -955,11 +1109,22 @@ func TestTopicMissingBody(t *testing.T) {
 		commandKey: joinCmd, toKey: "#topictest",
 	})
 
+	_, lastID := tserver.pollMessages(token, 0)
+
 	status, _ := tserver.sendCommand(token, map[string]any{
 		commandKey: "TOPIC", toKey: "#topictest",
 	})
-	if status != http.StatusBadRequest {
-		t.Fatalf("expected 400, got %d", status)
+	if status != http.StatusOK {
+		t.Fatalf("expected 200, got %d", status)
+	}
+
+	msgs, _ := tserver.pollMessages(token, lastID)
+
+	if !findNumeric(msgs, "461") {
+		t.Fatalf(
+			"expected ERR_NEEDMOREPARAMS (461), got %v",
+			msgs,
+		)
 	}
 }
 
@@ -1027,11 +1192,22 @@ func TestUnknownCommand(t *testing.T) {
 	tserver := newTestServer(t)
 	token := tserver.createSession("cmdtest")
 
+	_, lastID := tserver.pollMessages(token, 0)
+
 	status, _ := tserver.sendCommand(
 		token, map[string]any{commandKey: "BOGUS"},
 	)
-	if status != http.StatusBadRequest {
-		t.Fatalf("expected 400, got %d", status)
+	if status != http.StatusOK {
+		t.Fatalf("expected 200, got %d", status)
+	}
+
+	msgs, _ := tserver.pollMessages(token, lastID)
+
+	if !findNumeric(msgs, "421") {
+		t.Fatalf(
+			"expected ERR_UNKNOWNCOMMAND (421), got %v",
+			msgs,
+		)
 	}
 }
 
@@ -1278,12 +1454,18 @@ func TestLongPollTimeout(t *testing.T) {
 	tserver := newTestServer(t)
 	token := tserver.createSession("lp_timeout")
 
+	// Drain initial welcome/MOTD numerics.
+	_, lastID := tserver.pollMessages(token, 0)
+
 	start := time.Now()
 
 	resp, err := doRequestAuth(
 		t,
 		http.MethodGet,
-		tserver.url(apiMessages+"?timeout=1"),
+		tserver.url(fmt.Sprintf(
+			"%s?timeout=1&after=%d",
+			apiMessages, lastID,
+		)),
 		token,
 		nil,
 	)

internal/handlers/auth.go

@@ -80,7 +80,7 @@ func (hdlr *Handlers) handleRegister(
 		return
 	}
 
-	hdlr.deliverMOTD(request, clientID, sessionID)
+	hdlr.deliverMOTD(request, clientID, sessionID, payload.Nick)
 
 	hdlr.respondJSON(writer, request, map[string]any{
 		"id":    sessionID,
@@ -162,7 +162,7 @@ func (hdlr *Handlers) handleLogin(
 		return
 	}
 
-	sessionID, _, token, err :=
+	sessionID, clientID, token, err :=
 		hdlr.params.Database.LoginUser(
 			request.Context(),
 			payload.Nick,
@@ -178,6 +178,10 @@ func (hdlr *Handlers) handleLogin(
 		return
 	}
 
+	hdlr.deliverMOTD(
+		request, clientID, sessionID, payload.Nick,
+	)
+
 	hdlr.respondJSON(writer, request, map[string]any{
 		"id":    sessionID,
 		"nick":  payload.Nick,