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PLAT-39414 connector: resolve Reddit user IDs without a directory search #9

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PLAT-39414 connector: resolve Reddit user IDs without a directory search #9

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6cc62ef
PLAT-39414 connector: resolve Reddit user IDs without a directory search
Fizzadar Oct 20, 2026
50df6a9
PLAT-39414 connector: return members for newly created DMs
Fizzadar Oct 21, 2026
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4 changes: 4 additions & 0 deletions pkg/connector/ids.go
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Original file line number Diff line number Diff line change
Expand Up @@ -25,6 +25,10 @@ func makeUserLoginID(matrixUserID id.UserID) networkid.UserLoginID {
return networkid.UserLoginID(makeUserID(matrixUserID))
}

func isRedditUserID(userID networkid.UserID) bool {
return strings.HasPrefix(string(userID), "t2_") && len(userID) > 3 && strings.Trim(string(userID)[3:], "0123456789abcdefghijklmnopqrstuvwxyz") == ""
}

func userIDToMatrix(userID networkid.UserID, homeserver string) id.UserID {
return id.UserID(fmt.Sprintf("@%s:%s", userID, matrixServerName(homeserver)))
}
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3 changes: 1 addition & 2 deletions pkg/connector/membership.go
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Original file line number Diff line number Diff line change
Expand Up @@ -3,7 +3,6 @@ package connector
import (
"context"
"errors"
"strings"

"maunium.net/go/mautrix"
"maunium.net/go/mautrix/bridgev2"
Expand Down Expand Up @@ -55,7 +54,7 @@ func (r *RedditClient) HandleMatrixMembership(ctx context.Context, msg *bridgev2
case *bridgev2.UserLogin:
targetID = networkid.UserID(target.ID)
}
if !strings.HasPrefix(string(targetID), "t2_") || strings.Trim(string(targetID)[3:], "0123456789abcdefghijklmnopqrstuvwxyz") != "" || len(targetID) <= 3 {
if !isRedditUserID(targetID) {
return nil, permanentFailure(event.MessageStatusUnsupported, "only reddit accounts can be invited or removed")
}
if targetID == r.userID {
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53 changes: 39 additions & 14 deletions pkg/connector/startchat.go
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Original file line number Diff line number Diff line change
Expand Up @@ -2,13 +2,15 @@ package connector

import (
"context"
"errors"
"strings"

"go.mau.fi/util/ptr"
"maunium.net/go/mautrix"
"maunium.net/go/mautrix/bridgev2"
"maunium.net/go/mautrix/bridgev2/database"
"maunium.net/go/mautrix/bridgev2/networkid"
"maunium.net/go/mautrix/event"
"maunium.net/go/mautrix/id"
)

Expand All @@ -18,28 +20,43 @@ var (
_ bridgev2.GroupCreatingNetworkAPI = (*RedditClient)(nil)
)

// ResolveIdentifier turns a Reddit username (with or without "u/" prefix) into
// a ghost + optional DM. It first searches Reddit's user directory, then —
// if createChat is set — opens (or finds) a DM with the resolved user.
// ResolveIdentifier turns a Reddit username (with or without "u/" prefix) or
// t2_ user ID into a ghost + optional DM. Usernames are looked up in Reddit's
// user directory and IDs by profile; if createChat is set, it then opens (or
// finds) a DM with the resolved user.
func (r *RedditClient) ResolveIdentifier(ctx context.Context, identifier string, createChat bool) (*bridgev2.ResolveIdentifierResponse, error) {
identifier = strings.TrimSpace(identifier)
identifier = strings.TrimPrefix(identifier, "u/")
identifier = strings.TrimPrefix(identifier, "/u/")
if identifier == "" {
return nil, bridgev2.RespError(mautrix.MInvalidParam.WithMessage("Enter a Reddit username."))
}
results, err := r.remote().SearchUsers(ctx, identifier)
if err != nil {
return nil, wrapRedditRespError(err)
}
var match *userDirectoryHit

@indent indent Bot Oct 21, 2026

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⚪️ Nit · Usernames shaped like t2_ IDs no longer resolve through the directory

Any identifier matching t2_[0-9a-z]+ now goes only to GetProfile and skips SearchUsers. Reddit usernames can contain underscores and are case-insensitive, so a real account named like t2_abc typed as u/t2_abc is looked up as an ID. If no account has that ID the user gets 'No Reddit user found', and if one does they get the wrong person. Before this change SearchUsers matched it by display name. Fall back to the directory search when GetProfile returns MNotFound.

Found by Indent Review Agent

for _, hit := range results.Results {
display := hit.DisplayName
if strings.EqualFold(stripUserPrefix(display), identifier) || strings.EqualFold(string(hit.UserID), "@"+identifier+":reddit.com") {
if match != nil && match.UserID != hit.UserID {
return nil, bridgev2.RespError(mautrix.MInvalidParam.WithMessage("Multiple Reddit users match %q.", identifier))
if userID := networkid.UserID(identifier); isRedditUserID(userID) {
mxid := userIDToMatrix(userID, "")
profile, err := r.matrix().GetProfile(ctx, mxid)
if err == nil {
name := profile.DisplayName
if name == "" {
name = identifier
}
match = &userDirectoryHit{UserID: mxid, Name: name}
} else if !errors.Is(err, mautrix.MNotFound) {
return nil, wrapRedditRespError(err)
}
} else {
results, err := r.remote().SearchUsers(ctx, identifier)
if err != nil {
return nil, wrapRedditRespError(err)
}
for _, hit := range results.Results {
display := hit.DisplayName
if strings.EqualFold(stripUserPrefix(display), identifier) || strings.EqualFold(string(hit.UserID), "@"+identifier+":reddit.com") {
if match != nil && match.UserID != hit.UserID {
return nil, bridgev2.RespError(mautrix.MInvalidParam.WithMessage("Multiple Reddit users match %q.", identifier))
}
match = &userDirectoryHit{UserID: hit.UserID, Name: display, Avatar: string(hit.AvatarURL)}
}
match = &userDirectoryHit{UserID: hit.UserID, Name: display, Avatar: string(hit.AvatarURL)}
}
}
if match == nil {
Expand All @@ -59,7 +76,7 @@ func (r *RedditClient) ResolveIdentifier(ctx context.Context, identifier string,
if !createChat {
return resp, nil
}
roomID, _, err := r.remote().CreateOrGetDM(ctx, match.UserID)
roomID, created, err := r.remote().CreateOrGetDM(ctx, match.UserID)
if err != nil {
return nil, wrapRedditRespError(err)
}
Expand All @@ -70,6 +87,14 @@ func (r *RedditClient) ResolveIdentifier(ctx context.Context, identifier string,
Type: ptr.Ptr(database.RoomTypeDM),
},
}
if created {
members := &bridgev2.ChatMemberList{MemberMap: make(bridgev2.ChatMemberMap), OtherUserID: uid}
members.MemberMap.Set(bridgev2.ChatMember{EventSender: r.makeSender(userIDToMatrix(r.userID, "")), Membership: event.MembershipJoin})
members.MemberMap.Set(bridgev2.ChatMember{EventSender: r.makeSender(match.UserID), Membership: event.MembershipInvite})
resp.Chat.PortalInfo.Name = resp.UserInfo.Name
resp.Chat.PortalInfo.Members = members
resp.Chat.PortalInfo.CanBackfill = true
}
return resp, nil
}

Expand Down
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