webui: implement explicit initial render detection using State.message_count
Add explicit initial load completion detection to SketchTimeline component using
State.message_count to determine when all existing messages have been loaded
and the timeline is ready for initial render.
Implementation Changes:
1. DataManager Enhancement (data.ts):
- Add expectedMessageCount and isInitialLoadComplete state tracking
- Add 'initialLoadComplete' event type to DataManagerEventType union
- Add checkInitialLoadComplete() method to validate completion state
- Add handleInitialLoadComplete() event emission with message counts
- Handle empty conversation edge case (message_count: 0) with immediate completion
- Reset initial load state on connection establishment to handle reconnection
- Add getIsInitialLoadComplete() and getExpectedMessageCount() getters
2. Timeline Component Enhancement (sketch-timeline.ts):
- Add isInitialLoadComplete state property for render control
- Add dataManager property reference for event listener setup
- Add handleInitialLoadComplete() event handler with console logging
- Update render logic to show loading indicator until initial load complete
- Apply 'view-initialized' CSS class when initial load completes
- Only render messages and thinking indicator after initial load completion
- Set up DataManager event listeners in updated() lifecycle hook
- Clean up event listeners in disconnectedCallback() lifecycle hook
3. App Shell Integration (sketch-app-shell.ts):
- Pass dataManager reference to sketch-timeline component property
- Enable timeline component to receive initial load completion events
- Maintain existing data flow while adding explicit completion detection
4. Demo Mock Enhancement (handlers.ts):
- Initialize currentState with correct message_count based on initial messages
- Ensure proper message_count synchronization in SSE stream simulation
- Handle empty conversation demo scenario with accurate state
5. Enhanced CSS Styling (sketch-timeline.ts):
- Add opacity-based transitions for message appearance
- Show loading indicator before initial completion
- Hide message content until view-initialized class is applied
- Smooth transition from loading to content display
Technical Benefits:
- Eliminates reliance on implicit 'first message means streaming started' detection
- Provides explicit completion signal when all existing messages are loaded
- Handles edge cases like empty conversations (0 messages) immediately
- Prevents flash of incomplete content during initial load
- Enables proper loading states and smooth transitions
- Supports reconnection scenarios with state reset
User Experience Improvements:
- Clear loading indicator until conversation is fully loaded
- Smooth transition from loading to content display
- No flash of partial message lists during initial load
- Consistent behavior across different conversation sizes
- Better feedback during network delays or large conversation loads
Edge Case Handling:
- Empty conversations (message_count: 0) marked complete immediately
- Messages arriving before state handled gracefully
- Reconnection scenarios reset initial load detection
- Race conditions between state and message delivery resolved
This replaces the implicit initial load detection with explicit State.message_count
based completion detection, providing more reliable initial render timing and
better user experience during conversation loading.
Co-Authored-By: sketch <hello@sketch.dev>
Change-ID: s5126c2705d6ad6bak
diff --git a/webui/src/web-components/sketch-timeline.ts b/webui/src/web-components/sketch-timeline.ts
index 5dae38a..2f8e5e3 100644
--- a/webui/src/web-components/sketch-timeline.ts
+++ b/webui/src/web-components/sketch-timeline.ts
@@ -51,6 +51,13 @@
@property({ attribute: false })
state: State | null = null;
+ // Track initial load completion for better rendering control
+ @state()
+ private isInitialLoadComplete: boolean = false;
+
+ @property({ attribute: false })
+ dataManager: any = null; // Reference to DataManager for event listening
+
// Viewport rendering properties
@property({ attribute: false })
initialMessageCount: number = 30;
@@ -71,20 +78,20 @@
private loadingTimeoutId: number | null = null;
static styles = css`
- /* Hide views initially to prevent flash of content */
- .timeline-container .timeline,
- .timeline-container .diff-view,
- .timeline-container .chart-view,
- .timeline-container .terminal-view {
- visibility: hidden;
+ /* Hide message content initially to prevent flash of incomplete content */
+ .timeline-container:not(.view-initialized) sketch-timeline-message {
+ opacity: 0;
+ transition: opacity 0.2s ease-in;
}
- /* Will be set by JavaScript once we know which view to display */
- .timeline-container.view-initialized .timeline,
- .timeline-container.view-initialized .diff-view,
- .timeline-container.view-initialized .chart-view,
- .timeline-container.view-initialized .terminal-view {
- visibility: visible;
+ /* Show content once initial load is complete */
+ .timeline-container.view-initialized sketch-timeline-message {
+ opacity: 1;
+ }
+
+ /* Always show loading indicators */
+ .timeline-container .loading-indicator {
+ opacity: 1;
}
.timeline-container {
@@ -96,6 +103,7 @@
box-sizing: border-box;
overflow-x: hidden;
flex: 1;
+ min-height: 100px; /* Ensure container has height for loading indicator */
}
/* Chat-like timeline styles */
@@ -693,6 +701,35 @@
* Called after the component's properties have been updated
*/
updated(changedProperties: PropertyValues): void {
+ // Handle DataManager changes to set up event listeners
+ if (changedProperties.has("dataManager")) {
+ const oldDataManager = changedProperties.get("dataManager");
+
+ // Remove old event listener if it exists
+ if (oldDataManager) {
+ oldDataManager.removeEventListener(
+ "initialLoadComplete",
+ this.handleInitialLoadComplete,
+ );
+ }
+
+ // Add new event listener if dataManager is available
+ if (this.dataManager) {
+ this.dataManager.addEventListener(
+ "initialLoadComplete",
+ this.handleInitialLoadComplete,
+ );
+
+ // Check if initial load is already complete
+ if (
+ this.dataManager.getIsInitialLoadComplete &&
+ this.dataManager.getIsInitialLoadComplete()
+ ) {
+ this.isInitialLoadComplete = true;
+ }
+ }
+ }
+
// Handle scroll container changes first to prevent race conditions
if (changedProperties.has("scrollContainer")) {
// Cancel any ongoing loading operations since container is changing
@@ -813,6 +850,20 @@
}
/**
+ * Handle initial load completion from DataManager
+ */
+ private handleInitialLoadComplete = (eventData: {
+ messageCount: number;
+ expectedCount: number;
+ }): void => {
+ console.log(
+ `Timeline: Initial load complete - ${eventData.messageCount}/${eventData.expectedCount} messages`,
+ );
+ this.isInitialLoadComplete = true;
+ this.requestUpdate();
+ };
+
+ /**
* Set up observers for event-driven DOM monitoring
*/
private setupObservers(): void {
@@ -834,6 +885,14 @@
this._handleShowCommitDiff as EventListener,
);
+ // Remove DataManager event listener if connected
+ if (this.dataManager) {
+ this.dataManager.removeEventListener(
+ "initialLoadComplete",
+ this.handleInitialLoadComplete,
+ );
+ }
+
// Use our safe cleanup method
this.removeScrollListener();
}
@@ -888,10 +947,23 @@
const isThinking =
this.llmCalls > 0 || (this.toolCalls && this.toolCalls.length > 0);
+ // Apply view-initialized class when initial load is complete
+ const containerClass = this.isInitialLoadComplete
+ ? "timeline-container view-initialized"
+ : "timeline-container";
+
return html`
<div style="position: relative; height: 100%;">
<div id="scroll-container">
- <div class="timeline-container">
+ <div class="${containerClass}">
+ ${!this.isInitialLoadComplete
+ ? html`
+ <div class="loading-indicator">
+ <div class="loading-spinner"></div>
+ <span>Loading conversation...</span>
+ </div>
+ `
+ : ""}
${this.isLoadingOlderMessages
? html`
<div class="loading-indicator">
@@ -900,30 +972,32 @@
</div>
`
: ""}
- ${repeat(
- this.visibleMessages,
- this.messageKey,
- (message, index) => {
- // Find the previous message in the full filtered messages array
- const filteredMessages = this.filteredMessages;
- const messageIndex = filteredMessages.findIndex(
- (m) => m === message,
- );
- let previousMessage =
- messageIndex > 0
- ? filteredMessages[messageIndex - 1]
- : undefined;
+ ${this.isInitialLoadComplete
+ ? repeat(
+ this.visibleMessages,
+ this.messageKey,
+ (message, index) => {
+ // Find the previous message in the full filtered messages array
+ const filteredMessages = this.filteredMessages;
+ const messageIndex = filteredMessages.findIndex(
+ (m) => m === message,
+ );
+ let previousMessage =
+ messageIndex > 0
+ ? filteredMessages[messageIndex - 1]
+ : undefined;
- return html`<sketch-timeline-message
- .message=${message}
- .previousMessage=${previousMessage}
- .open=${false}
- .firstMessageIndex=${this.firstMessageIndex}
- .state=${this.state}
- ></sketch-timeline-message>`;
- },
- )}
- ${isThinking
+ return html`<sketch-timeline-message
+ .message=${message}
+ .previousMessage=${previousMessage}
+ .open=${false}
+ .firstMessageIndex=${this.firstMessageIndex}
+ .state=${this.state}
+ ></sketch-timeline-message>`;
+ },
+ )
+ : ""}
+ ${isThinking && this.isInitialLoadComplete
? html`
<div class="thinking-indicator">
<div class="thinking-bubble">