fix: chatd refactor (#26270)

Implements the chatd stabilization RFC.

Combines:
- https://github.com/coder/coder/pull/25908
- https://github.com/coder/coder/pull/25923
- https://github.com/coder/coder/pull/26109
- https://github.com/coder/coder/pull/26110
- https://github.com/coder/coder/pull/26111
- https://github.com/coder/coder/pull/26112

codersdk/chats.go

@@ -93,6 +93,7 @@ const (
 	ChatStatusCompleted      ChatStatus = "completed"
 	ChatStatusError          ChatStatus = "error"
 	ChatStatusRequiresAction ChatStatus = "requires_action"
+	ChatStatusInterrupting   ChatStatus = "interrupting"
 )
 
 // ChatClientType indicates whether a chat was created from the
@@ -1502,6 +1503,8 @@ const (
 	ChatStreamEventTypeQueueUpdate    ChatStreamEventType = "queue_update"
 	ChatStreamEventTypeRetry          ChatStreamEventType = "retry"
 	ChatStreamEventTypeActionRequired ChatStreamEventType = "action_required"
+	ChatStreamEventTypePreviewReset   ChatStreamEventType = "preview_reset"
+	ChatStreamEventTypeHistoryReset   ChatStreamEventType = "history_reset"
 )
 
 // ChatQueuedMessage represents a queued message waiting to be processed.
@@ -1515,8 +1518,11 @@ type ChatQueuedMessage struct {
 
 // ChatStreamMessagePart is a streamed message part update.
 type ChatStreamMessagePart struct {
-	Role ChatMessageRole `json:"role,omitempty"`
-	Part ChatMessagePart `json:"part"`
+	Role              ChatMessageRole `json:"role,omitempty"`
+	Part              ChatMessagePart `json:"part"`
+	HistoryVersion    int64           `json:"history_version,omitempty"`
+	GenerationAttempt int64           `json:"generation_attempt,omitempty"`
+	Seq               int64           `json:"seq,omitempty"`
 }
 
 // ChatStreamStatus represents an updated chat status.
@@ -3250,6 +3256,22 @@ func (c *ExperimentalClient) InterruptChat(ctx context.Context, chatID uuid.UUID
 	return chat, json.NewDecoder(res.Body).Decode(&chat)
 }
 
+// ReconcileInvalidChatState recovers a chat stuck in an invalid
+// execution state, moving it into an error state from which the caller
+// can send a new message or edit history to continue.
+func (c *ExperimentalClient) ReconcileInvalidChatState(ctx context.Context, chatID uuid.UUID) (Chat, error) {
+	res, err := c.Request(ctx, http.MethodPost, fmt.Sprintf("/api/experimental/chats/%s/reconcile-invalid", chatID), nil)
+	if err != nil {
+		return Chat{}, err
+	}
+	defer res.Body.Close()
+	if res.StatusCode != http.StatusOK {
+		return Chat{}, ReadBodyAsError(res)
+	}
+	var chat Chat
+	return chat, json.NewDecoder(res.Body).Decode(&chat)
+}
+
 // RegenerateChatTitle requests the server to regenerate the chat's
 // title using richer conversation context.
 func (c *ExperimentalClient) RegenerateChatTitle(ctx context.Context, chatID uuid.UUID) (Chat, error) {

codersdk/chats_test.go

@@ -172,6 +172,42 @@ func TestChatErrorKind_JSONRoundTrip(t *testing.T) {
 	require.Equal(t, codersdk.ChatErrorKindUsageLimit, decodedRetry.Kind)
 }
 
+func TestChatStreamEvent_JSONRoundTripIncludesResetTypesAndPartMetadata(t *testing.T) {
+	t.Parallel()
+
+	chatID := uuid.New()
+	events := []codersdk.ChatStreamEvent{
+		{Type: codersdk.ChatStreamEventTypePreviewReset, ChatID: chatID},
+		{Type: codersdk.ChatStreamEventTypeHistoryReset, ChatID: chatID},
+		{
+			Type:   codersdk.ChatStreamEventTypeMessagePart,
+			ChatID: chatID,
+			MessagePart: &codersdk.ChatStreamMessagePart{
+				Role:              codersdk.ChatMessageRoleAssistant,
+				Part:              codersdk.ChatMessageText("partial"),
+				HistoryVersion:    12,
+				GenerationAttempt: 3,
+				Seq:               4,
+			},
+		},
+	}
+	data, err := json.Marshal(events)
+	require.NoError(t, err)
+	require.Contains(t, string(data), `"type":"preview_reset"`)
+	require.Contains(t, string(data), `"type":"history_reset"`)
+	require.Contains(t, string(data), `"history_version":12`)
+	require.Contains(t, string(data), `"generation_attempt":3`)
+	require.Contains(t, string(data), `"seq":4`)
+
+	var decoded []codersdk.ChatStreamEvent
+	require.NoError(t, json.Unmarshal(data, &decoded))
+	require.Equal(t, codersdk.ChatStreamEventTypePreviewReset, decoded[0].Type)
+	require.Equal(t, codersdk.ChatStreamEventTypeHistoryReset, decoded[1].Type)
+	require.Equal(t, int64(12), decoded[2].MessagePart.HistoryVersion)
+	require.Equal(t, int64(3), decoded[2].MessagePart.GenerationAttempt)
+	require.Equal(t, int64(4), decoded[2].MessagePart.Seq)
+}
+
 func TestChatMessagePart_StripInternal(t *testing.T) {
 	t.Parallel()