fix: Detect streaming state in reasoning content blocks (#21549)

tools/server/public/index.html

@@ -18,7 +18,7 @@
 		<div style="display: contents">
 			<script>
 				{
-					__sveltekit_1y361v9 = {
+					__sveltekit_1wqaxod = {
 						base: new URL('.', location).pathname.slice(0, -1)
 					};
 

tools/server/webui/src/lib/components/app/chat/ChatMessages/ChatMessageAgenticContent.svelte

@@ -33,7 +33,7 @@
 	const showToolCallInProgress = $derived(config().showToolCallInProgress as boolean);
 	const showThoughtInProgress = $derived(config().showThoughtInProgress as boolean);
 
-	const sections = $derived(deriveAgenticSections(message, toolMessages, []));
+	const sections = $derived(deriveAgenticSections(message, toolMessages, [], isStreaming));
 
 	// Parse tool results with images
 	const sectionsParsed = $derived(

tools/server/webui/src/lib/utils/agentic.ts

@@ -38,14 +38,19 @@ export type ToolResultLine = {
 function deriveSingleTurnSections(
 	message: DatabaseMessage,
 	toolMessages: DatabaseMessage[] = [],
-	streamingToolCalls: ApiChatCompletionToolCall[] = []
+	streamingToolCalls: ApiChatCompletionToolCall[] = [],
+	isStreaming: boolean = false
 ): AgenticSection[] {
 	const sections: AgenticSection[] = [];
 
 	// 1. Reasoning content (from dedicated field)
 	if (message.reasoningContent) {
+		const toolCalls = parseToolCalls(message.toolCalls);
+		const hasContentAfterReasoning =
+			!!message.content?.trim() || toolCalls.length > 0 || streamingToolCalls.length > 0;
+		const isPending = isStreaming && !hasContentAfterReasoning;
 		sections.push({
-			type: AgenticSectionType.REASONING,
+			type: isPending ? AgenticSectionType.REASONING_PENDING : AgenticSectionType.REASONING,
 			content: message.reasoningContent
 		});
 	}
@@ -104,12 +109,13 @@ function deriveSingleTurnSections(
 export function deriveAgenticSections(
 	message: DatabaseMessage,
 	toolMessages: DatabaseMessage[] = [],
-	streamingToolCalls: ApiChatCompletionToolCall[] = []
+	streamingToolCalls: ApiChatCompletionToolCall[] = [],
+	isStreaming: boolean = false
 ): AgenticSection[] {
 	const hasAssistantContinuations = toolMessages.some((m) => m.role === MessageRole.ASSISTANT);
 
 	if (!hasAssistantContinuations) {
-		return deriveSingleTurnSections(message, toolMessages, streamingToolCalls);
+		return deriveSingleTurnSections(message, toolMessages, streamingToolCalls, isStreaming);
 	}
 
 	const sections: AgenticSection[] = [];
@@ -127,7 +133,12 @@ export function deriveAgenticSections(
 			const isLastTurn = i + 1 + turnToolMsgs.length >= toolMessages.length;
 
 			sections.push(
-				...deriveSingleTurnSections(msg, turnToolMsgs, isLastTurn ? streamingToolCalls : [])
+				...deriveSingleTurnSections(
+					msg,
+					turnToolMsgs,
+					isLastTurn ? streamingToolCalls : [],
+					isLastTurn && isStreaming
+				)
 			);
 
 			i += 1 + turnToolMsgs.length;

tools/server/webui/tests/unit/agentic-sections.test.ts

@@ -162,6 +162,36 @@ describe('deriveAgenticSections', () => {
 		expect(sections[4].content).toBe('Here is the analysis.');
 	});
 
+	it('returns REASONING_PENDING when streaming with only reasoning content', () => {
+		const msg = makeAssistant({
+			reasoningContent: 'Let me think about this...'
+		});
+		const sections = deriveAgenticSections(msg, [], [], true);
+		expect(sections).toHaveLength(1);
+		expect(sections[0].type).toBe(AgenticSectionType.REASONING_PENDING);
+		expect(sections[0].content).toBe('Let me think about this...');
+	});
+
+	it('returns REASONING (not pending) when streaming but text content has appeared', () => {
+		const msg = makeAssistant({
+			content: 'The answer is',
+			reasoningContent: 'Let me think...'
+		});
+		const sections = deriveAgenticSections(msg, [], [], true);
+		expect(sections).toHaveLength(2);
+		expect(sections[0].type).toBe(AgenticSectionType.REASONING);
+		expect(sections[1].type).toBe(AgenticSectionType.TEXT);
+	});
+
+	it('returns REASONING (not pending) when not streaming', () => {
+		const msg = makeAssistant({
+			reasoningContent: 'Let me think...'
+		});
+		const sections = deriveAgenticSections(msg, [], [], false);
+		expect(sections).toHaveLength(1);
+		expect(sections[0].type).toBe(AgenticSectionType.REASONING);
+	});
+
 	it('multi-turn: streaming tool calls on last turn', () => {
 		const assistant1 = makeAssistant({
 			toolCalls: JSON.stringify([