feat(threads): private threads and thread membership

README.md

@@ -24,7 +24,7 @@ msgs, _ := c.Messages().Read(ctx, "", 20, "")           // oldest-first
 | `Guilds()` | `List` `Sole` |
 | `Members()` | `List` `Get` `Kick` `Ban` |
 | `Roles()` | `List` `Create` `Update` `Delete` `Assign` `Unassign` |
-| `Threads()` | `Start` `CreateForum` `ForumPost` |
+| `Threads()` | `Start` `StartPrivate` `AddMember` `CreateForum` `ForumPost` |
 | `Reactions()` | `Add` `Remove` |
 | `Permissions()` | `Set` `Remove` |
 | `Webhooks()` | `Create` `List` `Delete` `Execute` |

threads.go

@@ -24,6 +24,31 @@ func (t *Threads) Start(ctx context.Context, channelID, messageID, name string)
 	return &ch, nil
 }
 
+// StartPrivate opens a private thread in channelID, with no parent message so
+// the channel shows no trace of it. Only invited members and moderators holding
+// MANAGE_THREADS can see it — invitable is false, so members cannot pull others
+// in. The creating bot is a member; add the humans with AddMember.
+func (t *Threads) StartPrivate(ctx context.Context, channelID, name string) (*Channel, error) {
+	var ch Channel
+	if err := t.rt.Do(ctx, http.MethodPost, "/channels/"+seg(channelID)+"/threads",
+		map[string]any{
+			"name":                  name,
+			"type":                  ChannelPrivateThread,
+			"invitable":             false,
+			"auto_archive_duration": autoArchive,
+		}, &ch); err != nil {
+		return nil, err
+	}
+	return &ch, nil
+}
+
+// AddMember gives userID access to threadID. A private thread is invisible until
+// its members are added, so this is what makes one usable by a person.
+func (t *Threads) AddMember(ctx context.Context, threadID, userID string) error {
+	return t.rt.Do(ctx, http.MethodPut,
+		"/channels/"+seg(threadID)+"/thread-members/"+seg(userID), nil, nil)
+}
+
 // CreateForum creates a forum channel named name in guildID (or the sole guild).
 func (t *Threads) CreateForum(ctx context.Context, guildID, name string) (*Channel, error) {
 	gid, err := t.def.resolveGuild(ctx, guildID)

threads_test.go

@@ -33,6 +33,45 @@ func TestThreadsStart(t *testing.T) {
 	}
 }
 
+// A private thread is created off the CHANNEL, never off a message: a message
+// would be the public trace the thread exists to avoid.
+func TestThreadsStartPrivate(t *testing.T) {
+	s := transport.NewStub().Reply(`{"id":"t9","name":"job","type":12}`)
+	ch, err := thr(s).StartPrivate(context.Background(), "c1", "job")
+	if err != nil {
+		t.Fatal(err)
+	}
+	if ch.ID != "t9" || ch.Type != ChannelPrivateThread {
+		t.Fatalf("thread = %+v", ch)
+	}
+	c := s.Last()
+	if c.Method != "POST" || c.Path != "/channels/c1/threads" {
+		t.Fatalf("call = %s %s", c.Method, c.Path)
+	}
+	body := c.Body.(map[string]any)
+	if body["type"] != ChannelPrivateThread {
+		t.Errorf("type = %v, want a private thread", body["type"])
+	}
+	// invitable would let any member drag others in, which defeats the point.
+	if body["invitable"] != false {
+		t.Errorf("invitable = %v, want false", body["invitable"])
+	}
+	if body["auto_archive_duration"] != autoArchive {
+		t.Errorf("auto_archive_duration = %v", body["auto_archive_duration"])
+	}
+}
+
+func TestThreadsAddMember(t *testing.T) {
+	s := transport.NewStub().Reply(``)
+	if err := thr(s).AddMember(context.Background(), "t9", "u1"); err != nil {
+		t.Fatal(err)
+	}
+	c := s.Last()
+	if c.Method != "PUT" || c.Path != "/channels/t9/thread-members/u1" {
+		t.Fatalf("call = %s %s", c.Method, c.Path)
+	}
+}
+
 func TestThreadsCreateForum(t *testing.T) {
 	s := transport.NewStub().
 		Reply(`[{"id":"g1"}]`).