All files / src/components/session SessionTimeline.tsx

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
import { useCallback, useEffect, useRef } from "react";
import { useAutoScroll } from "../../hooks/useAutoScroll";
import type { TimelineItem } from "../../types";
import { EmptyState } from "../shared/EmptyState";
import { TimelineEntry } from "./TimelineEntry";
 
const USER_MESSAGE_TOP_OFFSET = 8;
const ASSISTANT_MESSAGE_TOP_OFFSET = 8;
 
/**
 * Wait for all images inside `container` to finish loading so that
 * offsetTop calculations account for the final layout.  Resolves
 * immediately when there are no pending images.
 */
function waitForImages(container: HTMLElement): Promise<void> {
  const imgs = container.querySelectorAll<HTMLImageElement>("img");
  const pending = Array.from(imgs).filter((img) => !img.complete);
  if (pending.length === 0) return Promise.resolve();
  return Promise.all(
    pending.map(
      (img) =>
        new Promise<void>((resolve) => {
          img.addEventListener("load", () => resolve(), { once: true });
          img.addEventListener("error", () => resolve(), { once: true });
        }),
    ),
  ).then(() => {});
}
 
export function SessionTimeline({
  items,
  subAgents,
  connection,
  waitMessage,
  itemsVersion,
}: {
  items: TimelineItem[];
  subAgents: Record<string, { title: string; status: string }>;
  connection: "disconnected" | "connecting" | "connected";
  waitMessage: string | null;
  itemsVersion: number;
}) {
  const previousLengthRef = useRef<number | undefined>(undefined);
  const latestItem = items.at(-1);
  const latestItemIsUserMessage =
    latestItem?.kind === "message" && latestItem.role === "user";
  const { containerRef, showNewMessages, setShowNewMessages, scrollToBottom, userScrolledRef } =
    useAutoScroll(itemsVersion, { followOnChange: false });
 
  const scrollToTarget = useCallback(
    (container: HTMLElement, target: HTMLElement, offset: number) => {
      container.scrollTo({
        top: Math.max(target.offsetTop - offset, 0),
        behavior: "smooth",
      });
    },
    [],
  );
 
  useEffect(() => {
    const previousLength = previousLengthRef.current;
    previousLengthRef.current = items.length;
 
    const container = containerRef.current;
    if (!container) return;
 
    const isNewItem =
      previousLength !== undefined && items.length > previousLength;
 
    if (isNewItem && latestItem) {
      // New item added — scroll to the top of that item
      const target = container.querySelector<HTMLElement>(
        `[data-timeline-item-id="${CSS.escape(latestItem.itemId)}"]`,
      );
 
      if (latestItemIsUserMessage) {
        // Always scroll to user messages
        if (target) {
          void waitForImages(container).then(() => {
            scrollToTarget(container, target, USER_MESSAGE_TOP_OFFSET);
          });
        }
        userScrolledRef.current = false;
      } else if (!userScrolledRef.current) {
        // Scroll to top of new assistant/tool/thinking item
        if (target) {
          void waitForImages(container).then(() => {
            scrollToTarget(container, target, ASSISTANT_MESSAGE_TOP_OFFSET);
          });
        }
      } else {
        setShowNewMessages(true);
      }
    } else if (!isNewItem) {
      // Existing item content updated — stick to bottom
      if (!userScrolledRef.current) {
        container.scrollTo({ top: container.scrollHeight, behavior: "instant" });
      } else {
        setShowNewMessages(true);
      }
    }
  }, [containerRef, itemsVersion, items.length, latestItem, latestItemIsUserMessage, userScrolledRef, setShowNewMessages, scrollToTarget]);
 
  if (items.length === 0 && connection === "connected") {
    return (
      <div className="session-scroll-area" ref={containerRef}>
        <div className="timeline">
          <EmptyState
            title="No messages yet"
            description="Send a message to start the conversation"
          />
        </div>
      </div>
    );
  }
 
  return (
    <div className="session-scroll-area" ref={containerRef}>
      <div className="timeline">
        {items.map((item) => (
          <TimelineEntry
            key={item.itemId}
            item={item}
            subAgentTitle={item.subAgentId ? subAgents[item.subAgentId]?.title : undefined}
            subAgentStatus={item.subAgentId ? subAgents[item.subAgentId]?.status : undefined}
          />
        ))}
        {waitMessage ? (
          <div className="processing-indicator">
            <div className="spinner spinner--sm" />
            <span>{waitMessage}</span>
          </div>
        ) : null}
        {showNewMessages ? (
          <button
            type="button"
            className="timeline__new-messages"
            onClick={scrollToBottom}
          >
            New messages below
          </button>
        ) : null}
      </div>
    </div>
  );
}