Improve Discord bridge state handling

pkg/connector/bridge_state.go

@@ -0,0 +1,127 @@
+// mautrix-discord - A Matrix-Discord puppeting bridge.
+// Copyright (C) 2026 Tulir Asokan
+//
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Affero General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU Affero General Public License for more details.
+//
+// You should have received a copy of the GNU Affero General Public License
+// along with this program.  If not, see <https://www.gnu.org/licenses/>.
+
+package connector
+
+import (
+	"time"
+
+	"maunium.net/go/mautrix/bridgev2/status"
+)
+
+const (
+	DiscordNotLoggedIn   status.BridgeStateErrorCode = "discord-not-logged-in"
+	DiscordInvalidAuth   status.BridgeStateErrorCode = "discord-invalid-auth"
+	DiscordDisconnected  status.BridgeStateErrorCode = "discord-disconnected"
+	DiscordConnectFailed status.BridgeStateErrorCode = "discord-connect-failed"
+)
+
+const discordDisconnectDebounce = 7 * time.Second
+
+func init() {
+	status.BridgeStateHumanErrors.Update(status.BridgeStateErrorMap{
+		DiscordNotLoggedIn:   "You're not logged into Discord. Relogin to continue using the bridge.",
+		DiscordInvalidAuth:   "You were logged out of Discord. Relogin to continue using the bridge.",
+		DiscordDisconnected:  "Disconnected from Discord. Trying to reconnect.",
+		DiscordConnectFailed: "Connecting to Discord failed.",
+	})
+}
+
+func (d *DiscordClient) resetBridgeStateTracking() {
+	d.bridgeStateLock.Lock()
+	if d.disconnectTimer != nil {
+		d.disconnectTimer.Stop()
+		d.disconnectTimer = nil
+	}
+	d.invalidAuthDetected = false
+	d.bridgeStateLock.Unlock()
+}
+
+func (d *DiscordClient) markConnected() {
+	if d.UserLogin == nil {
+		return
+	}
+	d.bridgeStateLock.Lock()
+	if d.disconnectTimer != nil {
+		d.disconnectTimer.Stop()
+		d.disconnectTimer = nil
+	}
+	d.invalidAuthDetected = false
+	d.bridgeStateLock.Unlock()
+	d.UserLogin.BridgeState.Send(status.BridgeState{StateEvent: status.StateConnected})
+}
+
+func (d *DiscordClient) markInvalidAuth(message string) {
+	if d.UserLogin == nil {
+		return
+	}
+	d.bridgeStateLock.Lock()
+	d.invalidAuthDetected = true
+	if d.disconnectTimer != nil {
+		d.disconnectTimer.Stop()
+		d.disconnectTimer = nil
+	}
+	d.bridgeStateLock.Unlock()
+	d.UserLogin.BridgeState.Send(status.BridgeState{
+		StateEvent: status.StateBadCredentials,
+		Error:      DiscordInvalidAuth,
+		Message:    message,
+	})
+}
+
+func (d *DiscordClient) scheduleTransientDisconnect(message string) {
+	if d.UserLogin == nil {
+		return
+	}
+	d.bridgeStateLock.Lock()
+	if d.invalidAuthDetected {
+		d.bridgeStateLock.Unlock()
+		return
+	}
+	if d.disconnectTimer != nil {
+		d.disconnectTimer.Stop()
+	}
+	login := d.UserLogin
+	d.disconnectTimer = time.AfterFunc(discordDisconnectDebounce, func() {
+		d.bridgeStateLock.Lock()
+		d.disconnectTimer = nil
+		invalidAuth := d.invalidAuthDetected
+		d.bridgeStateLock.Unlock()
+		if invalidAuth {
+			return
+		}
+		login.BridgeState.Send(status.BridgeState{
+			StateEvent: status.StateTransientDisconnect,
+			Error:      DiscordDisconnected,
+			Message:    message,
+		})
+	})
+	d.bridgeStateLock.Unlock()
+}
+
+func (d *DiscordClient) sendConnectFailure(err error) {
+	if d.UserLogin == nil || err == nil {
+		return
+	}
+	d.UserLogin.BridgeState.Send(status.BridgeState{
+		StateEvent: status.StateUnknownError,
+		Error:      DiscordConnectFailed,
+		Message:    err.Error(),
+		Info: map[string]any{
+			"go_error": err.Error(),
+		},
+	})
+}

pkg/connector/client.go

@@ -48,6 +48,10 @@ type DiscordClient struct {
 
 	markedOpened     map[string]time.Time
 	markedOpenedLock sync.Mutex
+
+	bridgeStateLock     sync.Mutex
+	disconnectTimer     *time.Timer
+	invalidAuthDetected bool
 }
 
 func (d *DiscordConnector) LoadUserLogin(ctx context.Context, login *bridgev2.UserLogin) error {
@@ -95,6 +99,7 @@ func (d *DiscordClient) SetUp(ctx context.Context, meta *discordid.UserLoginMeta
 	}
 
 	d.markedOpened = make(map[string]time.Time)
+	d.resetBridgeStateTracking()
 }
 
 func (d *DiscordClient) Connect(ctx context.Context) {
@@ -104,7 +109,7 @@ func (d *DiscordClient) Connect(ctx context.Context) {
 		log.Error().Msg("No session present")
 		d.UserLogin.BridgeState.Send(status.BridgeState{
 			StateEvent: status.StateBadCredentials,
-			Error:      "discord-not-logged-in",
+			Error:      DiscordNotLoggedIn,
 		})
 		return
 	}
@@ -135,12 +140,16 @@ func (cl *DiscordClient) connect(ctx context.Context) error {
 	}
 	if err != nil {
 		log.Err(err).Msg("Failed to connect to Discord")
+		cl.sendConnectFailure(err)
 		return err
 	}
 
 	// Ensure that we actually have a user.
 	if !cl.IsLoggedIn() {
-		return fmt.Errorf("unknown identity even after connecting to Discord")
+		err := fmt.Errorf("unknown identity even after connecting to Discord")
+		log.Err(err).Msg("No Discord user available after connecting")
+		cl.sendConnectFailure(err)
+		return err
 	}
 	user := cl.Session.State.User
 	log.Info().Str("user_id", user.ID).Str("user_username", user.Username).Msg("Connected to Discord")

pkg/connector/handlediscord.go

@@ -25,7 +25,6 @@ import (
 	"github.com/rs/zerolog"
 	"maunium.net/go/mautrix/bridgev2"
 	"maunium.net/go/mautrix/bridgev2/networkid"
-	"maunium.net/go/mautrix/bridgev2/status"
 
 	"go.mau.fi/mautrix-discord/pkg/discordid"
 )
@@ -196,16 +195,21 @@ func (d *DiscordClient) handleDiscordEvent(rawEvt any) {
 		Logger()
 
 	switch evt := rawEvt.(type) {
+	case *discordgo.Connect:
+		log.Info().Msg("Discord gateway connected")
+		d.markConnected()
+	case *discordgo.Disconnect:
+		log.Info().Msg("Discord gateway disconnected")
+		d.scheduleTransientDisconnect("")
+	case *discordgo.InvalidAuth:
+		log.Warn().Msg("Discord gateway reported invalid auth")
+		d.markInvalidAuth("You have been logged out of Discord, please reconnect")
 	case *discordgo.Ready:
 		log.Info().Msg("Received READY dispatch from discordgo")
-		d.UserLogin.BridgeState.Send(status.BridgeState{
-			StateEvent: status.StateConnected,
-		})
+		d.markConnected()
 	case *discordgo.Resumed:
 		log.Info().Msg("Received RESUMED dispatch from discordgo")
-		d.UserLogin.BridgeState.Send(status.BridgeState{
-			StateEvent: status.StateConnected,
-		})
+		d.markConnected()
 	case *discordgo.MessageCreate:
 		if evt.Author == nil {
 			log.Trace().Int("message_type", int(evt.Message.Type)).

pkg/connector/login_generic.go

@@ -97,6 +97,11 @@ func (dl *DiscordGenericLogin) FinalizeCreatingLogin(ctx context.Context, token
 		Str("user_username", user.Username).
 		Msg("Logged in to Discord")
 
+	// We already opened the gateway session before creating the UserLogin,
+	// which means the initial READY/CONNECT event was dropped. Send Connected
+	// here so infra gets login status for new logins.
+	client.markConnected()
+
 	return ul, nil
 }