web-ui package

packages/web-ui/src/components/StreamingMessageContainer.ts

@@ -0,0 +1,101 @@
+import { html } from "@mariozechner/mini-lit";
+import type { AgentTool, Message, ToolResultMessage } from "@mariozechner/pi-ai";
+import { LitElement } from "lit";
+import { property, state } from "lit/decorators.js";
+
+export class StreamingMessageContainer extends LitElement {
+	@property({ type: Array }) tools: AgentTool[] = [];
+	@property({ type: Boolean }) isStreaming = false;
+	@property({ type: Object }) pendingToolCalls?: Set<string>;
+	@property({ type: Object }) toolResultsById?: Map<string, ToolResultMessage>;
+
+	@state() private _message: Message | null = null;
+	private _pendingMessage: Message | null = null;
+	private _updateScheduled = false;
+	private _immediateUpdate = false;
+
+	protected override createRenderRoot(): HTMLElement | DocumentFragment {
+		return this;
+	}
+
+	override connectedCallback(): void {
+		super.connectedCallback();
+		this.style.display = "block";
+	}
+
+	// Public method to update the message with batching for performance
+	public setMessage(message: Message | null, immediate = false) {
+		// Store the latest message
+		this._pendingMessage = message;
+
+		// If this is an immediate update (like clearing), apply it right away
+		if (immediate || message === null) {
+			this._immediateUpdate = true;
+			this._message = message;
+			this.requestUpdate();
+			// Cancel any pending updates since we're clearing
+			this._pendingMessage = null;
+			this._updateScheduled = false;
+			return;
+		}
+
+		// Otherwise batch updates for performance during streaming
+		if (!this._updateScheduled) {
+			this._updateScheduled = true;
+
+			requestAnimationFrame(async () => {
+				// Only apply the update if we haven't been cleared
+				if (!this._immediateUpdate && this._pendingMessage !== null) {
+					// Deep clone the message to ensure Lit detects changes in nested properties
+					// (like toolCall.arguments being mutated during streaming)
+					this._message = JSON.parse(JSON.stringify(this._pendingMessage));
+					this.requestUpdate();
+				}
+				// Reset for next batch
+				this._pendingMessage = null;
+				this._updateScheduled = false;
+				this._immediateUpdate = false;
+			});
+		}
+	}
+
+	override render() {
+		// Show loading indicator if loading but no message yet
+		if (!this._message) {
+			if (this.isStreaming)
+				return html`<div class="flex flex-col gap-3 mb-3">
+					<span class="mx-4 inline-block w-2 h-4 bg-muted-foreground animate-pulse"></span>
+				</div>`;
+			return html``; // Empty until a message is set
+		}
+		const msg = this._message;
+
+		if (msg.role === "toolResult") {
+			// Skip standalone tool result in streaming; the stable list will render paired tool-message
+			return html``;
+		} else if (msg.role === "user") {
+			// Skip standalone tool result in streaming; the stable list will render it immediiately
+			return html``;
+		} else if (msg.role === "assistant") {
+			// Assistant message - render inline tool messages during streaming
+			return html`
+				<div class="flex flex-col gap-3 mb-3">
+					<assistant-message
+						.message=${msg}
+						.tools=${this.tools}
+						.isStreaming=${this.isStreaming}
+						.pendingToolCalls=${this.pendingToolCalls}
+						.toolResultsById=${this.toolResultsById}
+						.hideToolCalls=${false}
+					></assistant-message>
+					${this.isStreaming ? html`<span class="mx-4 inline-block w-2 h-4 bg-muted-foreground animate-pulse"></span>` : ""}
+				</div>
+			`;
+		}
+	}
+}
+
+// Register custom element
+if (!customElements.get("streaming-message-container")) {
+	customElements.define("streaming-message-container", StreamingMessageContainer);
+}