fix: explicitly disable add_generation_prompt when using continue_final_message

Some tokenizers (e.g., Kimi-K2-Thinking) default add_generation_prompt=True,
which conflicts with continue_final_message=True. Explicitly set
add_generation_prompt=False to avoid the ValueError.

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

dashboard/package-lock.json

@@ -863,7 +863,6 @@
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 			"dev": true,
 			"license": "MIT",
-			"peer": true,
 			"dependencies": {
 				"@standard-schema/spec": "^1.0.0",
 				"@sveltejs/acorn-typescript": "^1.0.5",
@@ -903,7 +902,6 @@
 			"integrity": "sha512-Y1Cs7hhTc+a5E9Va/xwKlAJoariQyHY+5zBgCZg4PFWNYQ1nMN9sjK1zhw1gK69DuqVP++sht/1GZg1aRwmAXQ==",
 			"dev": true,
 			"license": "MIT",
-			"peer": true,
 			"dependencies": {
 				"@sveltejs/vite-plugin-svelte-inspector": "^4.0.1",
 				"debug": "^4.4.1",
@@ -1520,7 +1518,6 @@
 			"integrity": "sha512-LCCV0HdSZZZb34qifBsyWlUmok6W7ouER+oQIGBScS8EsZsQbrtFTUrDX4hOl+CS6p7cnNC4td+qrSVGSCTUfQ==",
 			"dev": true,
 			"license": "MIT",
-			"peer": true,
 			"dependencies": {
 				"undici-types": "~6.21.0"
 			}
@@ -1530,7 +1527,6 @@
 			"resolved": "https://registry.npmjs.org/acorn/-/acorn-8.15.0.tgz",
 			"integrity": "sha512-NZyJarBfL7nWwIq+FDL6Zp/yHEhePMNnnJ0y3qfieCrmNvYct8uvtiV41UvlSe6apAfk0fY1FbWx+NwfmpvtTg==",
 			"license": "MIT",
-			"peer": true,
 			"bin": {
 				"acorn": "bin/acorn"
 			},
@@ -1943,7 +1939,6 @@
 			"integrity": "sha512-fmTRWbNMmsmWq6xJV8D19U/gw/bwrHfNXxrIN+HfZgnzqTHp9jOmKMhsTUjXOJnZOdZY9Q28y4yebKzqDKlxlQ==",
 			"dev": true,
 			"license": "ISC",
-			"peer": true,
 			"engines": {
 				"node": ">=12"
 			}
@@ -2651,7 +2646,6 @@
 			"integrity": "sha512-5gTmgEY/sqK6gFXLIsQNH19lWb4ebPDLA4SdLP7dsWkIXHWlG66oPuVvXSGFPppYZz8ZDZq0dYYrbHfBCVUb1Q==",
 			"dev": true,
 			"license": "MIT",
-			"peer": true,
 			"engines": {
 				"node": ">=12"
 			},
@@ -2839,7 +2833,6 @@
 			"resolved": "https://registry.npmjs.org/svelte/-/svelte-5.45.3.tgz",
 			"integrity": "sha512-ngKXNhNvwPzF43QqEhDOue7TQTrG09em1sd4HBxVF0Wr2gopAmdEWan+rgbdgK4fhBtSOTJO8bYU4chUG7VXZQ==",
 			"license": "MIT",
-			"peer": true,
 			"dependencies": {
 				"@jridgewell/remapping": "^2.3.4",
 				"@jridgewell/sourcemap-codec": "^1.5.0",
@@ -2984,7 +2977,6 @@
 			"integrity": "sha512-jl1vZzPDinLr9eUt3J/t7V6FgNEw9QjvBPdysz9KfQDD41fQrC2Y4vKQdiaUpFT4bXlb1RHhLpp8wtm6M5TgSw==",
 			"dev": true,
 			"license": "Apache-2.0",
-			"peer": true,
 			"bin": {
 				"tsc": "bin/tsc",
 				"tsserver": "bin/tsserver"
@@ -3006,7 +2998,6 @@
 			"integrity": "sha512-+Oxm7q9hDoLMyJOYfUYBuHQo+dkAloi33apOPP56pzj+vsdJDzr+j1NISE5pyaAuKL4A3UD34qd0lx5+kfKp2g==",
 			"dev": true,
 			"license": "MIT",
-			"peer": true,
 			"dependencies": {
 				"esbuild": "^0.25.0",
 				"fdir": "^6.4.4",

dashboard/src/lib/components/ChatMessages.svelte

@@ -1,14 +1,16 @@
 <script lang="ts">
-	import { 
-		messages, 
-		currentResponse, 
+	import {
+		messages,
+		currentResponse,
 		isLoading,
 		deleteMessage,
 		editAndRegenerate,
-		regenerateLastResponse
+		regenerateLastResponse,
+		regenerateFromToken
 	} from '$lib/stores/app.svelte';
 	import type { MessageAttachment } from '$lib/stores/app.svelte';
 	import MarkdownContent from './MarkdownContent.svelte';
+	import TokenHeatmap from './TokenHeatmap.svelte';
 
 	interface Props {
 		class?: string;
@@ -95,6 +97,23 @@
 let copiedMessageId = $state<string | null>(null);
 let expandedThinkingMessageIds = $state<Set<string>>(new Set());
 
+// Uncertainty view state - tracks which messages show token heatmap
+let uncertaintyViewMessageIds = $state<Set<string>>(new Set());
+
+function toggleUncertaintyView(messageId: string) {
+	const newSet = new Set(uncertaintyViewMessageIds);
+	if (newSet.has(messageId)) {
+		newSet.delete(messageId);
+	} else {
+		newSet.add(messageId);
+	}
+	uncertaintyViewMessageIds = newSet;
+}
+
+function isUncertaintyViewEnabled(messageId: string): boolean {
+	return uncertaintyViewMessageIds.has(messageId);
+}
+
 	function formatTimestamp(timestamp: number): string {
 		return new Date(timestamp).toLocaleTimeString('en-US', { 
 			hour12: false,
@@ -366,7 +385,17 @@ function isThinkingExpanded(messageId: string): boolean {
 									</div>
 								{/if}
 								<div class="text-xs text-foreground">
-									<MarkdownContent content={message.content || (loading ? response : '')} />
+									{#if message.role === 'assistant' && isUncertaintyViewEnabled(message.id) && message.tokens && message.tokens.length > 0}
+										<!-- Uncertainty heatmap view -->
+										<TokenHeatmap
+											tokens={message.tokens}
+											isGenerating={loading}
+											onRegenerateFrom={(tokenIndex) => regenerateFromToken(message.id, tokenIndex)}
+										/>
+									{:else}
+										<!-- Normal markdown view -->
+										<MarkdownContent content={message.content || (loading ? response : '')} />
+									{/if}
 									{#if loading && !message.content}
 										<span class="inline-block w-2 h-4 bg-exo-yellow/70 ml-1 cursor-blink"></span>
 									{/if}
@@ -419,6 +448,19 @@ function isThinkingExpanded(messageId: string): boolean {
 								</svg>
 							</button>
 						{/if}
+
+						<!-- Uncertainty view toggle (assistant messages with tokens only) -->
+						{#if message.role === 'assistant' && message.tokens && message.tokens.length > 0}
+							<button
+								onclick={() => toggleUncertaintyView(message.id)}
+								class="p-1.5 transition-colors rounded cursor-pointer {isUncertaintyViewEnabled(message.id) ? 'text-exo-yellow' : 'text-exo-light-gray hover:text-exo-yellow'}"
+								title={isUncertaintyViewEnabled(message.id) ? 'Hide uncertainty' : 'Show uncertainty'}
+							>
+								<svg class="w-3.5 h-3.5" fill="none" viewBox="0 0 24 24" stroke="currentColor">
+									<path stroke-linecap="round" stroke-linejoin="round" stroke-width="2" d="M9 19v-6a2 2 0 00-2-2H5a2 2 0 00-2 2v6a2 2 0 002 2h2a2 2 0 002-2zm0 0V9a2 2 0 012-2h2a2 2 0 012 2v10m-6 0a2 2 0 002 2h2a2 2 0 002-2m0 0V5a2 2 0 012-2h2a2 2 0 012 2v14a2 2 0 01-2 2h-2a2 2 0 01-2-2z" />
+								</svg>
+							</button>
+						{/if}
 						
 						<!-- Delete button -->
 						<button

dashboard/src/lib/components/TokenHeatmap.svelte

@@ -0,0 +1,192 @@
+<script lang="ts">
+	import type { TokenData } from '$lib/stores/app.svelte';
+
+	interface Props {
+		tokens: TokenData[];
+		class?: string;
+		isGenerating?: boolean;
+		onRegenerateFrom?: (tokenIndex: number) => void;
+	}
+
+	let { tokens, class: className = '', isGenerating = false, onRegenerateFrom }: Props = $props();
+
+	// Tooltip state - track both token data and index
+	let hoveredTokenIndex = $state<number | null>(null);
+	let hoveredPosition = $state<{ x: number; y: number } | null>(null);
+	let isTooltipHovered = $state(false);
+	let hideTimeoutId: ReturnType<typeof setTimeout> | null = null;
+
+	// Derive the hovered token from the index (stable across re-renders)
+	const hoveredToken = $derived(
+		hoveredTokenIndex !== null && hoveredPosition && tokens[hoveredTokenIndex]
+			? { token: tokens[hoveredTokenIndex], index: hoveredTokenIndex, ...hoveredPosition }
+			: null
+	);
+
+	/**
+	 * Get confidence styling based on probability.
+	 * Following Apple design principles: high confidence tokens blend in,
+	 * only uncertainty draws attention.
+	 */
+	function getConfidenceClass(probability: number): string {
+		if (probability > 0.8) return 'text-inherit'; // Expected tokens - blend in
+		if (probability > 0.5) return 'bg-gray-500/10 text-inherit'; // Slight hint
+		if (probability > 0.2) return 'bg-amber-500/15 text-amber-200/90'; // Subtle warmth
+		return 'bg-red-500/20 text-red-200/90'; // Draws attention
+	}
+
+	/**
+	 * Get border/underline styling for uncertain tokens
+	 */
+	function getBorderClass(probability: number): string {
+		if (probability > 0.8) return 'border-transparent'; // No border for expected
+		if (probability > 0.5) return 'border-gray-500/20';
+		if (probability > 0.2) return 'border-amber-500/30';
+		return 'border-red-500/40';
+	}
+
+	function clearHideTimeout() {
+		if (hideTimeoutId) {
+			clearTimeout(hideTimeoutId);
+			hideTimeoutId = null;
+		}
+	}
+
+	function handleMouseEnter(event: MouseEvent, token: TokenData, index: number) {
+		clearHideTimeout();
+		const rect = (event.target as HTMLElement).getBoundingClientRect();
+		hoveredTokenIndex = index;
+		hoveredPosition = {
+			x: rect.left + rect.width / 2,
+			y: rect.top - 10
+		};
+	}
+
+	function handleMouseLeave() {
+		clearHideTimeout();
+		// Use longer delay during generation to account for re-renders
+		const delay = isGenerating ? 300 : 100;
+		hideTimeoutId = setTimeout(() => {
+			if (!isTooltipHovered) {
+				hoveredTokenIndex = null;
+				hoveredPosition = null;
+			}
+		}, delay);
+	}
+
+	function handleTooltipEnter() {
+		clearHideTimeout();
+		isTooltipHovered = true;
+	}
+
+	function handleTooltipLeave() {
+		isTooltipHovered = false;
+		hoveredTokenIndex = null;
+		hoveredPosition = null;
+	}
+
+	function handleRegenerate() {
+		if (hoveredToken && onRegenerateFrom) {
+			const indexToRegenerate = hoveredToken.index;
+			// Clear hover state immediately
+			hoveredTokenIndex = null;
+			hoveredPosition = null;
+			isTooltipHovered = false;
+			// Call regenerate
+			onRegenerateFrom(indexToRegenerate);
+		}
+	}
+
+	function formatProbability(prob: number): string {
+		return (prob * 100).toFixed(1) + '%';
+	}
+
+	function formatLogprob(logprob: number): string {
+		return logprob.toFixed(3);
+	}
+
+	function getProbabilityColor(probability: number): string {
+		if (probability > 0.8) return 'text-gray-300';
+		if (probability > 0.5) return 'text-gray-400';
+		if (probability > 0.2) return 'text-amber-400';
+		return 'text-red-400';
+	}
+</script>
+
+<div class="token-heatmap leading-relaxed {className}">
+	{#each tokens as tokenData, i (i)}
+		<span
+			role="button"
+			tabindex="0"
+			class="token-span inline rounded px-0.5 py-0.5 cursor-pointer transition-all duration-150 border {getConfidenceClass(tokenData.probability)} {getBorderClass(tokenData.probability)} hover:opacity-80"
+			onmouseenter={(e) => handleMouseEnter(e, tokenData, i)}
+			onmouseleave={handleMouseLeave}
+		>{tokenData.token}</span>
+	{/each}
+</div>
+
+<!-- Tooltip -->
+{#if hoveredToken}
+	<div
+		class="fixed z-50"
+		style="left: {hoveredToken.x}px; top: {hoveredToken.y}px; transform: translate(-50%, -100%);"
+		onmouseenter={handleTooltipEnter}
+		onmouseleave={handleTooltipLeave}
+	>
+		<div class="bg-gray-900/95 backdrop-blur-sm border border-gray-700/50 rounded-xl shadow-xl p-3 text-sm min-w-48">
+			<!-- Token info -->
+			<div class="mb-2">
+				<span class="text-gray-500 text-xs">Token:</span>
+				<span class="text-white font-mono ml-1">"{hoveredToken.token.token}"</span>
+				<span class="{getProbabilityColor(hoveredToken.token.probability)} ml-2">{formatProbability(hoveredToken.token.probability)}</span>
+			</div>
+
+			<div class="text-gray-400 text-xs mb-1">
+				logprob: <span class="text-gray-300 font-mono">{formatLogprob(hoveredToken.token.logprob)}</span>
+			</div>
+
+			<!-- Top alternatives -->
+			{#if hoveredToken.token.topLogprobs.length > 0}
+				<div class="border-t border-gray-700/50 mt-2 pt-2">
+					<div class="text-gray-500 text-xs mb-1">Alternatives:</div>
+					{#each hoveredToken.token.topLogprobs.slice(0, 5) as alt, idx (idx)}
+						{@const altProb = Math.exp(alt.logprob)}
+						<div class="flex justify-between items-center text-xs py-0.5">
+							<span class="text-gray-300 font-mono truncate max-w-24">"{alt.token}"</span>
+							<span class="text-gray-400 ml-2">{formatProbability(altProb)}</span>
+						</div>
+					{/each}
+				</div>
+			{/if}
+
+			<!-- Regenerate button -->
+			{#if onRegenerateFrom}
+				<button
+					onclick={handleRegenerate}
+					class="w-full mt-2 pt-2 border-t border-gray-700/50 flex items-center justify-center gap-1.5 text-xs text-gray-400 hover:text-white transition-colors cursor-pointer"
+				>
+					<svg class="w-3 h-3" fill="none" viewBox="0 0 24 24" stroke="currentColor">
+						<path stroke-linecap="round" stroke-linejoin="round" stroke-width="2" d="M4 4v5h.582m15.356 2A8.001 8.001 0 004.582 9m0 0H9m11 11v-5h-.581m0 0a8.003 8.003 0 01-15.357-2m15.357 2H15" />
+					</svg>
+					Regenerate from here
+				</button>
+			{/if}
+		</div>
+		<!-- Arrow -->
+		<div class="absolute left-1/2 -translate-x-1/2 top-full">
+			<div class="border-8 border-transparent border-t-gray-900"></div>
+		</div>
+	</div>
+{/if}
+
+<style>
+	.token-heatmap {
+		word-wrap: break-word;
+		white-space: pre-wrap;
+	}
+
+	.token-span {
+		margin: 0;
+		border-width: 1px;
+	}
+</style>

dashboard/src/lib/stores/app.svelte.ts

@@ -182,6 +182,20 @@ export interface MessageAttachment {
 	mimeType?: string;
 }
 
+// Token-level data for uncertainty visualization
+export interface TopLogprob {
+	token: string;
+	logprob: number;
+	bytes?: number[];
+}
+
+export interface TokenData {
+	token: string;
+	logprob: number;
+	probability: number; // exp(logprob)
+	topLogprobs: TopLogprob[];
+}
+
 export interface Message {
 	id: string;
 	role: "user" | "assistant" | "system";
@@ -191,6 +205,7 @@ export interface Message {
 	attachments?: MessageAttachment[];
 	ttftMs?: number; // Time to first token in ms (for assistant messages)
 	tps?: number; // Tokens per second (for assistant messages)
+	tokens?: TokenData[]; // Token-level data for uncertainty visualization
 }
 
 export interface Conversation {
@@ -368,6 +383,21 @@ class AppStore {
 	private fetchInterval: ReturnType<typeof setInterval> | null = null;
 	private previewsInterval: ReturnType<typeof setInterval> | null = null;
 	private lastConversationPersistTs = 0;
+	private currentRequestController: AbortController | null = null;
+
+	/**
+	 * Abort any in-flight generation request
+	 */
+	abortCurrentRequest(): boolean {
+		if (this.currentRequestController) {
+			this.currentRequestController.abort();
+			this.currentRequestController = null;
+			this.isLoading = false;
+			this.currentResponse = "";
+			return true;
+		}
+		return false;
+	}
 
 	constructor() {
 		if (browser) {
@@ -1046,6 +1076,10 @@ class AppStore {
 		// Remove any messages after the user message
 		this.messages = this.messages.slice(0, lastUserIndex + 1);
 
+		// Create abort controller for this request
+		const controller = new AbortController();
+		this.currentRequestController = controller;
+
 		// Resend the message to get a new response
 		this.isLoading = true;
 		this.currentResponse = "";
@@ -1107,7 +1141,10 @@ class AppStore {
 					model: modelToUse,
 					messages: apiMessages,
 					stream: true,
+					logprobs: true,
+					top_logprobs: 5,
 				}),
+				signal: controller.signal,
 			});
 
 			if (!response.ok) {
@@ -1140,6 +1177,7 @@ class AppStore {
 			const decoder = new TextDecoder();
 			let fullContent = "";
 			let partialLine = "";
+			const collectedTokens: TokenData[] = [];
 
 			while (true) {
 				const { done, value } = await reader.read();
@@ -1158,6 +1196,29 @@ class AppStore {
 							const json = JSON.parse(trimmed.slice(6));
 							const delta = json.choices?.[0]?.delta?.content;
 							if (delta) {
+								// Extract logprobs for uncertainty visualization
+								const logprobsData = json.choices?.[0]?.logprobs;
+								if (logprobsData?.content?.[0]) {
+									const logprobItem = logprobsData.content[0];
+									const tokenData: TokenData = {
+										token: logprobItem.token || delta,
+										logprob: logprobItem.logprob ?? 0,
+										probability: Math.exp(logprobItem.logprob ?? 0),
+										topLogprobs: (logprobItem.top_logprobs || []).map(
+											(item: {
+												token: string;
+												logprob: number;
+												bytes?: number[];
+											}) => ({
+												token: item.token,
+												logprob: item.logprob,
+												bytes: item.bytes,
+											}),
+										),
+									};
+									collectedTokens.push(tokenData);
+								}
+
 								fullContent += delta;
 								const { displayContent, thinkingContent } =
 									this.stripThinkingTags(fullContent);
@@ -1170,6 +1231,7 @@ class AppStore {
 								if (idx !== -1) {
 									this.messages[idx].content = displayContent;
 									this.messages[idx].thinking = thinkingContent || undefined;
+									this.messages[idx].tokens = [...collectedTokens];
 								}
 								this.persistActiveConversation();
 							}
@@ -1187,9 +1249,16 @@ class AppStore {
 			if (idx !== -1) {
 				this.messages[idx].content = displayContent;
 				this.messages[idx].thinking = thinkingContent || undefined;
+				if (collectedTokens.length > 0) {
+					this.messages[idx].tokens = collectedTokens;
+				}
 			}
 			this.persistActiveConversation();
 		} catch (error) {
+			// Don't show error for aborted requests (user cancelled)
+			if (error instanceof Error && error.name === "AbortError") {
+				return;
+			}
 			const idx = this.messages.findIndex((m) => m.id === assistantMessage.id);
 			if (idx !== -1) {
 				this.messages[idx].content =
@@ -1197,6 +1266,10 @@ class AppStore {
 			}
 			this.persistActiveConversation();
 		} finally {
+			// Clean up controller if this is still the active request
+			if (this.currentRequestController === controller) {
+				this.currentRequestController = null;
+			}
 			this.isLoading = false;
 			this.currentResponse = "";
 			this.updateActiveConversation();
@@ -1218,6 +1291,210 @@ class AppStore {
 		this.tps = null;
 	}
 
+	/**
+	 * Regenerate from a specific token in an assistant message.
+	 * Keeps content up to and including the specified token, then continues generation.
+	 * If a generation is already in progress, it will be aborted first.
+	 */
+	async regenerateFromToken(
+		messageId: string,
+		tokenIndex: number,
+	): Promise<void> {
+		// Abort any in-flight request first
+		this.abortCurrentRequest();
+
+		const messageIdx = this.messages.findIndex((m) => m.id === messageId);
+		if (messageIdx === -1) return;
+
+		const message = this.messages[messageIdx];
+		if (message.role !== "assistant" || !message.tokens) return;
+
+		// Get tokens up to and including the specified index
+		const keptTokens = message.tokens.slice(0, tokenIndex + 1);
+		const prefixText = keptTokens.map((t) => t.token).join("");
+
+		// Update the message with just the prefix
+		this.messages[messageIdx].content = prefixText;
+		this.messages[messageIdx].tokens = keptTokens;
+		this.messages[messageIdx].thinking = undefined;
+		this.persistActiveConversation();
+
+		// Start loading
+		this.isLoading = true;
+		this.currentResponse = prefixText;
+
+		// Create abort controller for this request
+		const controller = new AbortController();
+		this.currentRequestController = controller;
+
+		try {
+			const systemPrompt = {
+				role: "system" as const,
+				content:
+					"You are a helpful AI assistant. Respond directly and concisely. Do not show your reasoning or thought process.",
+			};
+
+			// Build messages: all messages before this one, plus the prefix as assistant
+			const apiMessages: { role: string; content: string }[] = [systemPrompt];
+			for (let i = 0; i < messageIdx; i++) {
+				const m = this.messages[i];
+				apiMessages.push({ role: m.role, content: m.content || "" });
+			}
+			// Add the prefix as a partial assistant response to continue from
+			apiMessages.push({ role: "assistant", content: prefixText });
+
+			// Determine which model to use
+			let modelToUse = this.selectedChatModel;
+			if (!modelToUse) {
+				const firstInstanceKey = Object.keys(this.instances)[0];
+				if (firstInstanceKey) {
+					const instance = this.instances[firstInstanceKey] as
+						| Record<string, unknown>
+						| undefined;
+					if (instance) {
+						const keys = Object.keys(instance);
+						if (keys.length === 1) {
+							const inst = instance[keys[0]] as
+								| { shardAssignments?: { modelId?: string } }
+								| undefined;
+							modelToUse = inst?.shardAssignments?.modelId || "";
+						}
+					}
+				}
+			}
+
+			if (!modelToUse) {
+				this.messages[messageIdx].content =
+					prefixText + "\n\nError: No model available.";
+				this.isLoading = false;
+				this.updateActiveConversation();
+				return;
+			}
+
+			const response = await fetch("/v1/chat/completions", {
+				method: "POST",
+				headers: { "Content-Type": "application/json" },
+				body: JSON.stringify({
+					model: modelToUse,
+					messages: apiMessages,
+					stream: true,
+					logprobs: true,
+					top_logprobs: 5,
+					continue_from_prefix: true,
+				}),
+				signal: controller.signal,
+			});
+
+			if (!response.ok) {
+				const errorText = await response.text();
+				this.messages[messageIdx].content =
+					prefixText + `\n\nError: ${response.status} - ${errorText}`;
+				this.isLoading = false;
+				this.updateActiveConversation();
+				return;
+			}
+
+			const reader = response.body?.getReader();
+			if (!reader) {
+				this.messages[messageIdx].content =
+					prefixText + "\n\nError: No response stream available";
+				this.isLoading = false;
+				this.updateActiveConversation();
+				return;
+			}
+
+			const decoder = new TextDecoder();
+			let fullContent = prefixText;
+			let partialLine = "";
+			const collectedTokens: TokenData[] = [...keptTokens];
+
+			while (true) {
+				const { done, value } = await reader.read();
+				if (done) break;
+
+				const chunk = decoder.decode(value, { stream: true });
+				const lines = (partialLine + chunk).split("\n");
+				partialLine = lines.pop() || "";
+
+				for (const line of lines) {
+					const trimmed = line.trim();
+					if (!trimmed || trimmed === "data: [DONE]") continue;
+
+					if (trimmed.startsWith("data: ")) {
+						try {
+							const json = JSON.parse(trimmed.slice(6));
+							const delta = json.choices?.[0]?.delta?.content;
+							if (delta) {
+								// Extract logprobs for uncertainty visualization
+								const logprobsData = json.choices?.[0]?.logprobs;
+								if (logprobsData?.content?.[0]) {
+									const logprobItem = logprobsData.content[0];
+									const tokenData: TokenData = {
+										token: logprobItem.token || delta,
+										logprob: logprobItem.logprob ?? 0,
+										probability: Math.exp(logprobItem.logprob ?? 0),
+										topLogprobs: (logprobItem.top_logprobs || []).map(
+											(item: {
+												token: string;
+												logprob: number;
+												bytes?: number[];
+											}) => ({
+												token: item.token,
+												logprob: item.logprob,
+												bytes: item.bytes,
+											}),
+										),
+									};
+									collectedTokens.push(tokenData);
+								}
+
+								fullContent += delta;
+								const { displayContent, thinkingContent } =
+									this.stripThinkingTags(fullContent);
+								this.currentResponse = displayContent;
+
+								this.messages[messageIdx].content = displayContent;
+								this.messages[messageIdx].thinking =
+									thinkingContent || undefined;
+								this.messages[messageIdx].tokens = [...collectedTokens];
+								this.persistActiveConversation();
+							}
+						} catch {
+							// Skip malformed JSON
+						}
+					}
+				}
+			}
+
+			// Final cleanup
+			const { displayContent, thinkingContent } =
+				this.stripThinkingTags(fullContent);
+			this.messages[messageIdx].content = displayContent;
+			this.messages[messageIdx].thinking = thinkingContent || undefined;
+			if (collectedTokens.length > 0) {
+				this.messages[messageIdx].tokens = collectedTokens;
+			}
+			this.persistActiveConversation();
+		} catch (error) {
+			// Don't show error for aborted requests (user cancelled)
+			if (error instanceof Error && error.name === "AbortError") {
+				return;
+			}
+			this.messages[messageIdx].content =
+				prefixText +
+				`\n\nError: ${error instanceof Error ? error.message : "Unknown error"}`;
+			this.persistActiveConversation();
+		} finally {
+			// Clean up controller if this is still the active request
+			if (this.currentRequestController === controller) {
+				this.currentRequestController = null;
+			}
+			this.isLoading = false;
+			this.currentResponse = "";
+			this.updateActiveConversation();
+		}
+	}
+
 	/**
 	 * Strip thinking tags from content for display.
 	 * Handles both complete <think>...</think> blocks and in-progress <think>... blocks during streaming.
@@ -1274,6 +1551,10 @@ class AppStore {
 			this.startChat();
 		}
 
+		// Create abort controller for this request
+		const controller = new AbortController();
+		this.currentRequestController = controller;
+
 		this.isLoading = true;
 		this.currentResponse = "";
 		this.ttftMs = null;
@@ -1408,7 +1689,10 @@ class AppStore {
 					messages: apiMessages,
 					temperature: 0.7,
 					stream: true,
+					logprobs: true,
+					top_logprobs: 5,
 				}),
+				signal: controller.signal,
 			});
 
 			if (!response.ok) {
@@ -1424,6 +1708,7 @@ class AppStore {
 			const decoder = new TextDecoder();
 			let fullContent = "";
 			let buffer = "";
+			const collectedTokens: TokenData[] = [];
 
 			while (true) {
 				const { done, value } = await reader.read();
@@ -1463,6 +1748,29 @@ class AppStore {
 									this.tps = (tokenCount / elapsed) * 1000;
 								}
 
+								// Extract logprobs for uncertainty visualization
+								const logprobsData = parsed.choices?.[0]?.logprobs;
+								if (logprobsData?.content?.[0]) {
+									const logprobItem = logprobsData.content[0];
+									const tokenData: TokenData = {
+										token: logprobItem.token || tokenContent,
+										logprob: logprobItem.logprob ?? 0,
+										probability: Math.exp(logprobItem.logprob ?? 0),
+										topLogprobs: (logprobItem.top_logprobs || []).map(
+											(item: {
+												token: string;
+												logprob: number;
+												bytes?: number[];
+											}) => ({
+												token: item.token,
+												logprob: item.logprob,
+												bytes: item.bytes,
+											}),
+										),
+									};
+									collectedTokens.push(tokenData);
+								}
+
 								fullContent += tokenContent;
 
 								// Strip thinking tags for display and extract thinking content
@@ -1477,6 +1785,8 @@ class AppStore {
 								if (idx !== -1) {
 									this.messages[idx].content = displayContent;
 									this.messages[idx].thinking = thinkingContent || undefined;
+									// Update tokens during streaming for real-time visualization
+									this.messages[idx].tokens = [...collectedTokens];
 								}
 								this.persistActiveConversation();
 							}
@@ -1524,9 +1834,17 @@ class AppStore {
 				if (this.tps !== null) {
 					this.messages[idx].tps = this.tps;
 				}
+				// Store token data for uncertainty visualization
+				if (collectedTokens.length > 0) {
+					this.messages[idx].tokens = collectedTokens;
+				}
 			}
 			this.persistActiveConversation();
 		} catch (error) {
+			// Don't show error for aborted requests (user cancelled)
+			if (error instanceof Error && error.name === "AbortError") {
+				return;
+			}
 			console.error("Error sending message:", error);
 			// Update the assistant message with error
 			const idx = this.messages.findIndex((m) => m.id === assistantMessage.id);
@@ -1536,6 +1854,10 @@ class AppStore {
 			}
 			this.persistActiveConversation();
 		} finally {
+			// Clean up controller if this is still the active request
+			if (this.currentRequestController === controller) {
+				this.currentRequestController = null;
+			}
 			this.isLoading = false;
 			this.currentResponse = "";
 			this.updateActiveConversation();
@@ -1615,6 +1937,9 @@ export const editMessage = (messageId: string, newContent: string) =>
 export const editAndRegenerate = (messageId: string, newContent: string) =>
 	appStore.editAndRegenerate(messageId, newContent);
 export const regenerateLastResponse = () => appStore.regenerateLastResponse();
+export const regenerateFromToken = (messageId: string, tokenIndex: number) =>
+	appStore.regenerateFromToken(messageId, tokenIndex);
+export const abortCurrentRequest = () => appStore.abortCurrentRequest();
 
 // Conversation actions
 export const conversations = () => appStore.conversations;

src/exo/master/adapters/__init__.py

@@ -0,0 +1 @@
+"""API adapters for different API formats (Claude, OpenAI Responses, etc.)."""

src/exo/master/adapters/claude.py

@@ -0,0 +1,184 @@
+"""Claude Messages API adapter for converting requests/responses."""
+
+from collections.abc import AsyncGenerator
+
+from exo.shared.types.api import (
+    ChatCompletionChoice,
+    ChatCompletionMessage,
+    ChatCompletionResponse,
+    FinishReason,
+)
+from exo.shared.types.chunks import TokenChunk
+from exo.shared.types.claude_api import (
+    ClaudeContentBlockDeltaEvent,
+    ClaudeContentBlockStartEvent,
+    ClaudeContentBlockStopEvent,
+    ClaudeMessageDelta,
+    ClaudeMessageDeltaEvent,
+    ClaudeMessageDeltaUsage,
+    ClaudeMessagesRequest,
+    ClaudeMessagesResponse,
+    ClaudeMessageStart,
+    ClaudeMessageStartEvent,
+    ClaudeMessageStopEvent,
+    ClaudeStopReason,
+    ClaudeTextBlock,
+    ClaudeTextDelta,
+    ClaudeUsage,
+)
+from exo.shared.types.common import CommandId
+from exo.shared.types.tasks import ChatCompletionTaskParams
+
+
+def finish_reason_to_claude_stop_reason(
+    finish_reason: FinishReason | None,
+) -> ClaudeStopReason | None:
+    """Map OpenAI finish_reason to Claude stop_reason."""
+    if finish_reason is None:
+        return None
+    mapping: dict[FinishReason, ClaudeStopReason] = {
+        "stop": "end_turn",
+        "length": "max_tokens",
+        "tool_calls": "tool_use",
+        "content_filter": "end_turn",
+        "function_call": "tool_use",
+    }
+    return mapping.get(finish_reason, "end_turn")
+
+
+def claude_request_to_chat_params(
+    request: ClaudeMessagesRequest,
+) -> ChatCompletionTaskParams:
+    """Convert Claude Messages API request to internal ChatCompletionTaskParams."""
+    messages: list[ChatCompletionMessage] = []
+
+    # Add system message if present
+    if request.system:
+        if isinstance(request.system, str):
+            messages.append(
+                ChatCompletionMessage(role="system", content=request.system)
+            )
+        else:
+            # List of text blocks
+            system_text = "".join(block.text for block in request.system)
+            messages.append(ChatCompletionMessage(role="system", content=system_text))
+
+    # Convert messages
+    for msg in request.messages:
+        content: str
+        if isinstance(msg.content, str):
+            content = msg.content
+        else:
+            # Concatenate text blocks (images not supported for MVP)
+            text_parts: list[str] = []
+            for block in msg.content:
+                if isinstance(block, ClaudeTextBlock):
+                    text_parts.append(block.text)
+            content = "".join(text_parts)
+
+        messages.append(ChatCompletionMessage(role=msg.role, content=content))
+
+    return ChatCompletionTaskParams(
+        model=request.model,
+        messages=messages,
+        max_tokens=request.max_tokens,
+        temperature=request.temperature,
+        top_p=request.top_p,
+        top_k=request.top_k,
+        stop=request.stop_sequences,
+        stream=request.stream,
+    )
+
+
+def chat_response_to_claude_response(
+    response: ChatCompletionResponse,
+) -> ClaudeMessagesResponse:
+    """Convert internal ChatCompletionResponse to Claude Messages API response."""
+    content_text = ""
+    stop_reason: ClaudeStopReason | None = None
+
+    if response.choices:
+        choice = response.choices[0]
+        if isinstance(choice, ChatCompletionChoice) and choice.message.content:
+            content_text = (
+                choice.message.content
+                if isinstance(choice.message.content, str)
+                else str(choice.message.content)
+            )
+        stop_reason = finish_reason_to_claude_stop_reason(choice.finish_reason)
+
+    # Use actual usage data from response if available
+    input_tokens = response.usage.prompt_tokens if response.usage else 0
+    output_tokens = response.usage.completion_tokens if response.usage else 0
+
+    return ClaudeMessagesResponse(
+        id=f"msg_{response.id}",
+        model=response.model,
+        content=[ClaudeTextBlock(text=content_text)],
+        stop_reason=stop_reason,
+        usage=ClaudeUsage(
+            input_tokens=input_tokens,
+            output_tokens=output_tokens,
+        ),
+    )
+
+
+async def generate_claude_stream(
+    command_id: CommandId,
+    model: str,
+    chunk_stream: AsyncGenerator[TokenChunk, None],
+) -> AsyncGenerator[str, None]:
+    """Generate Claude Messages API streaming events from TokenChunks."""
+    # Initial message_start event
+    initial_message = ClaudeMessageStart(
+        id=f"msg_{command_id}",
+        model=model,
+        content=[],
+        stop_reason=None,
+        usage=ClaudeUsage(input_tokens=0, output_tokens=0),
+    )
+    start_event = ClaudeMessageStartEvent(message=initial_message)
+    yield f"event: message_start\ndata: {start_event.model_dump_json()}\n\n"
+
+    # content_block_start
+    block_start = ClaudeContentBlockStartEvent(
+        index=0, content_block=ClaudeTextBlock(text="")
+    )
+    yield f"event: content_block_start\ndata: {block_start.model_dump_json()}\n\n"
+
+    output_tokens = 0
+    stop_reason: ClaudeStopReason | None = None
+    last_stats = None
+
+    async for chunk in chunk_stream:
+        output_tokens += 1  # Count each chunk as one token
+        last_stats = chunk.stats or last_stats
+
+        # content_block_delta
+        delta_event = ClaudeContentBlockDeltaEvent(
+            index=0,
+            delta=ClaudeTextDelta(text=chunk.text),
+        )
+        yield f"event: content_block_delta\ndata: {delta_event.model_dump_json()}\n\n"
+
+        if chunk.finish_reason is not None:
+            stop_reason = finish_reason_to_claude_stop_reason(chunk.finish_reason)
+
+    # Use actual token count from stats if available
+    if last_stats is not None:
+        output_tokens = last_stats.generation_tokens
+
+    # content_block_stop
+    block_stop = ClaudeContentBlockStopEvent(index=0)
+    yield f"event: content_block_stop\ndata: {block_stop.model_dump_json()}\n\n"
+
+    # message_delta
+    message_delta = ClaudeMessageDeltaEvent(
+        delta=ClaudeMessageDelta(stop_reason=stop_reason),
+        usage=ClaudeMessageDeltaUsage(output_tokens=output_tokens),
+    )
+    yield f"event: message_delta\ndata: {message_delta.model_dump_json()}\n\n"
+
+    # message_stop
+    message_stop = ClaudeMessageStopEvent()
+    yield f"event: message_stop\ndata: {message_stop.model_dump_json()}\n\n"

src/exo/master/adapters/responses.py

@@ -0,0 +1,199 @@
+"""OpenAI Responses API adapter for converting requests/responses."""
+
+from collections.abc import AsyncGenerator
+
+from exo.shared.types.api import (
+    ChatCompletionChoice,
+    ChatCompletionMessage,
+    ChatCompletionResponse,
+)
+from exo.shared.types.chunks import TokenChunk
+from exo.shared.types.common import CommandId
+from exo.shared.types.openai_responses import (
+    ResponseCompletedEvent,
+    ResponseContentPartAddedEvent,
+    ResponseContentPartDoneEvent,
+    ResponseCreatedEvent,
+    ResponseInProgressEvent,
+    ResponseMessageItem,
+    ResponseOutputItemAddedEvent,
+    ResponseOutputItemDoneEvent,
+    ResponseOutputText,
+    ResponsesRequest,
+    ResponsesResponse,
+    ResponseTextDeltaEvent,
+    ResponseTextDoneEvent,
+    ResponseUsage,
+)
+from exo.shared.types.tasks import ChatCompletionTaskParams
+
+
+def responses_request_to_chat_params(
+    request: ResponsesRequest,
+) -> ChatCompletionTaskParams:
+    """Convert OpenAI Responses API request to internal ChatCompletionTaskParams."""
+    messages: list[ChatCompletionMessage] = []
+
+    # Add instructions as system message if present
+    if request.instructions:
+        messages.append(
+            ChatCompletionMessage(role="system", content=request.instructions)
+        )
+
+    # Convert input to messages
+    if isinstance(request.input, str):
+        messages.append(ChatCompletionMessage(role="user", content=request.input))
+    else:
+        for msg in request.input:
+            messages.append(
+                ChatCompletionMessage(
+                    role=msg.role,
+                    content=msg.content,
+                )
+            )
+
+    return ChatCompletionTaskParams(
+        model=request.model,
+        messages=messages,
+        max_tokens=request.max_output_tokens,
+        temperature=request.temperature,
+        top_p=request.top_p,
+        stream=request.stream,
+    )
+
+
+def chat_response_to_responses_response(
+    response: ChatCompletionResponse,
+) -> ResponsesResponse:
+    """Convert internal ChatCompletionResponse to OpenAI Responses API response."""
+    output_text = ""
+
+    if response.choices:
+        choice = response.choices[0]
+        if isinstance(choice, ChatCompletionChoice) and choice.message.content:
+            output_text = (
+                choice.message.content
+                if isinstance(choice.message.content, str)
+                else str(choice.message.content)
+            )
+
+    item_id = f"item_{response.id}"
+    output_item = ResponseMessageItem(
+        id=item_id,
+        content=[ResponseOutputText(text=output_text)],
+    )
+
+    usage = None
+    if response.usage:
+        usage = ResponseUsage(
+            input_tokens=response.usage.prompt_tokens,
+            output_tokens=response.usage.completion_tokens,
+            total_tokens=response.usage.total_tokens,
+        )
+
+    return ResponsesResponse(
+        id=f"resp_{response.id}",
+        model=response.model,
+        output=[output_item],
+        output_text=output_text,
+        usage=usage,
+    )
+
+
+async def generate_responses_stream(
+    command_id: CommandId,
+    model: str,
+    chunk_stream: AsyncGenerator[TokenChunk, None],
+) -> AsyncGenerator[str, None]:
+    """Generate OpenAI Responses API streaming events from TokenChunks."""
+    response_id = f"resp_{command_id}"
+    item_id = f"item_{command_id}"
+
+    # response.created
+    initial_response = ResponsesResponse(
+        id=response_id,
+        model=model,
+        status="in_progress",
+        output=[],
+        output_text="",
+    )
+    created_event = ResponseCreatedEvent(response=initial_response)
+    yield f"event: response.created\ndata: {created_event.model_dump_json()}\n\n"
+
+    # response.in_progress
+    in_progress_event = ResponseInProgressEvent(response=initial_response)
+    yield f"event: response.in_progress\ndata: {in_progress_event.model_dump_json()}\n\n"
+
+    # response.output_item.added
+    initial_item = ResponseMessageItem(
+        id=item_id,
+        content=[ResponseOutputText(text="")],
+        status="in_progress",
+    )
+    item_added = ResponseOutputItemAddedEvent(output_index=0, item=initial_item)
+    yield f"event: response.output_item.added\ndata: {item_added.model_dump_json()}\n\n"
+
+    # response.content_part.added
+    initial_part = ResponseOutputText(text="")
+    part_added = ResponseContentPartAddedEvent(
+        output_index=0, content_index=0, part=initial_part
+    )
+    yield f"event: response.content_part.added\ndata: {part_added.model_dump_json()}\n\n"
+
+    accumulated_text = ""
+    last_stats = None
+
+    async for chunk in chunk_stream:
+        accumulated_text += chunk.text
+        last_stats = chunk.stats or last_stats
+
+        # response.output_text.delta
+        delta_event = ResponseTextDeltaEvent(
+            output_index=0,
+            content_index=0,
+            delta=chunk.text,
+        )
+        yield f"event: response.output_text.delta\ndata: {delta_event.model_dump_json()}\n\n"
+
+    # response.output_text.done
+    text_done = ResponseTextDoneEvent(
+        output_index=0, content_index=0, text=accumulated_text
+    )
+    yield f"event: response.output_text.done\ndata: {text_done.model_dump_json()}\n\n"
+
+    # response.content_part.done
+    final_part = ResponseOutputText(text=accumulated_text)
+    part_done = ResponseContentPartDoneEvent(
+        output_index=0, content_index=0, part=final_part
+    )
+    yield f"event: response.content_part.done\ndata: {part_done.model_dump_json()}\n\n"
+
+    # response.output_item.done
+    final_item = ResponseMessageItem(
+        id=item_id,
+        content=[ResponseOutputText(text=accumulated_text)],
+        status="completed",
+    )
+    item_done = ResponseOutputItemDoneEvent(output_index=0, item=final_item)
+    yield f"event: response.output_item.done\ndata: {item_done.model_dump_json()}\n\n"
+
+    # Create usage from stats if available
+    usage = None
+    if last_stats is not None:
+        usage = ResponseUsage(
+            input_tokens=last_stats.prompt_tokens,
+            output_tokens=last_stats.generation_tokens,
+            total_tokens=last_stats.prompt_tokens + last_stats.generation_tokens,
+        )
+
+    # response.completed
+    final_response = ResponsesResponse(
+        id=response_id,
+        model=model,
+        status="completed",
+        output=[final_item],
+        output_text=accumulated_text,
+        usage=usage,
+    )
+    completed_event = ResponseCompletedEvent(response=final_response)
+    yield f"event: response.completed\ndata: {completed_event.model_dump_json()}\n\n"

src/exo/master/api.py

@@ -14,6 +14,16 @@ from hypercorn.config import Config
 from hypercorn.typing import ASGIFramework
 from loguru import logger
 
+from exo.master.adapters.claude import (
+    chat_response_to_claude_response,
+    claude_request_to_chat_params,
+    generate_claude_stream,
+)
+from exo.master.adapters.responses import (
+    chat_response_to_responses_response,
+    generate_responses_stream,
+    responses_request_to_chat_params,
+)
 from exo.master.placement import place_instance as get_instance_placements
 from exo.shared.apply import apply
 from exo.shared.election import ElectionMessage
@@ -31,6 +41,8 @@ from exo.shared.types.api import (
     DeleteInstanceResponse,
     FinishReason,
     GenerationStats,
+    Logprobs,
+    LogprobsContentItem,
     ModelList,
     ModelListModel,
     PlaceInstanceParams,
@@ -39,6 +51,10 @@ from exo.shared.types.api import (
     StreamingChoiceResponse,
 )
 from exo.shared.types.chunks import TokenChunk
+from exo.shared.types.claude_api import (
+    ClaudeMessagesRequest,
+    ClaudeMessagesResponse,
+)
 from exo.shared.types.commands import (
     ChatCompletion,
     Command,
@@ -52,6 +68,10 @@ from exo.shared.types.common import CommandId, NodeId, SessionId
 from exo.shared.types.events import ChunkGenerated, Event, ForwarderEvent, IndexedEvent
 from exo.shared.types.memory import Memory
 from exo.shared.types.models import ModelId, ModelMetadata
+from exo.shared.types.openai_responses import (
+    ResponsesRequest,
+    ResponsesResponse,
+)
 from exo.shared.types.state import State
 from exo.shared.types.tasks import ChatCompletionTaskParams
 from exo.shared.types.worker.instances import Instance, InstanceId, InstanceMeta
@@ -65,6 +85,20 @@ from exo.utils.event_buffer import OrderedBuffer
 def chunk_to_response(
     chunk: TokenChunk, command_id: CommandId
 ) -> ChatCompletionResponse:
+    # Build logprobs if available
+    logprobs: Logprobs | None = None
+    if chunk.logprob is not None:
+        logprobs = Logprobs(
+            content=[
+                LogprobsContentItem(
+                    token=chunk.text,
+                    logprob=chunk.logprob,
+                    bytes=list(chunk.text.encode("utf-8")),
+                    top_logprobs=chunk.top_logprobs or [],
+                )
+            ]
+        )
+
     return ChatCompletionResponse(
         id=command_id,
         created=int(time.time()),
@@ -73,6 +107,7 @@ def chunk_to_response(
             StreamingChoiceResponse(
                 index=0,
                 delta=ChatCompletionMessage(role="assistant", content=chunk.text),
+                logprobs=logprobs,
                 finish_reason=chunk.finish_reason,
             )
         ],
@@ -168,6 +203,8 @@ class API:
             self.chat_completions
         )
         self.app.post("/bench/chat/completions")(self.bench_chat_completions)
+        self.app.post("/v1/messages", response_model=None)(self.claude_messages)
+        self.app.post("/v1/responses", response_model=None)(self.openai_responses)
         self.app.get("/state")(lambda: self.state)
         self.app.get("/events")(lambda: self._event_log)
 
@@ -548,6 +585,75 @@ class API:
         response = await self._collect_chat_completion_with_stats(command.command_id)
         return response
 
+    async def claude_messages(
+        self, payload: ClaudeMessagesRequest
+    ) -> ClaudeMessagesResponse | StreamingResponse:
+        """Handle Claude Messages API requests."""
+        chat_params = claude_request_to_chat_params(payload)
+        model_meta = await resolve_model_meta(chat_params.model)
+        chat_params.model = model_meta.model_id
+
+        if not any(
+            instance.shard_assignments.model_id == chat_params.model
+            for instance in self.state.instances.values()
+        ):
+            await self._trigger_notify_user_to_download_model(chat_params.model)
+            raise HTTPException(
+                status_code=404,
+                detail=f"No instance found for model {chat_params.model}",
+            )
+
+        command = ChatCompletion(request_params=chat_params)
+        await self._send(command)
+
+        if payload.stream:
+            return StreamingResponse(
+                generate_claude_stream(
+                    command.command_id,
+                    payload.model,
+                    self._chat_chunk_stream(command.command_id),
+                ),
+                media_type="text/event-stream",
+            )
+
+        response = await self._collect_chat_completion(command.command_id)
+        return chat_response_to_claude_response(response)
+
+    async def openai_responses(
+        self, payload: ResponsesRequest
+    ) -> ResponsesResponse | StreamingResponse:
+        """Handle OpenAI Responses API requests."""
+        chat_params = responses_request_to_chat_params(payload)
+
+        model_meta = await resolve_model_meta(chat_params.model)
+        chat_params.model = model_meta.model_id
+
+        if not any(
+            instance.shard_assignments.model_id == chat_params.model
+            for instance in self.state.instances.values()
+        ):
+            await self._trigger_notify_user_to_download_model(chat_params.model)
+            raise HTTPException(
+                status_code=404,
+                detail=f"No instance found for model {chat_params.model}",
+            )
+
+        command = ChatCompletion(request_params=chat_params)
+        await self._send(command)
+
+        if payload.stream:
+            return StreamingResponse(
+                generate_responses_stream(
+                    command.command_id,
+                    payload.model,
+                    self._chat_chunk_stream(command.command_id),
+                ),
+                media_type="text/event-stream",
+            )
+
+        response = await self._collect_chat_completion(command.command_id)
+        return chat_response_to_responses_response(response)
+
     def _calculate_total_available_memory(self) -> Memory:
         """Calculate total available memory across all nodes in bytes."""
         total_available = Memory()
@@ -612,9 +718,17 @@ class API:
                         and event.command_id in self._chat_completion_queues
                     ):
                         assert isinstance(event.chunk, TokenChunk)
-                        await self._chat_completion_queues[event.command_id].send(
-                            event.chunk
-                        )
+                        try:
+                            await self._chat_completion_queues[event.command_id].send(
+                                event.chunk
+                            )
+                        except (anyio.BrokenResourceError, KeyError):
+                            # Client disconnected, queue was closed/removed - this is expected
+                            # when clients abort requests (e.g., regenerate from token)
+                            logger.debug(
+                                f"Client disconnected for command {event.command_id}, "
+                                "dropping chunk"
+                            )
 
     async def _pause_on_new_election(self):
         with self.election_receiver as ems:

src/exo/master/tests/test_claude_api.py

@@ -0,0 +1,392 @@
+"""Tests for Claude Messages API conversion functions and types."""
+
+import json
+from typing import Any, cast
+
+import pydantic
+import pytest
+
+from exo.master.adapters.claude import (
+    chat_response_to_claude_response,
+    claude_request_to_chat_params,
+    finish_reason_to_claude_stop_reason,
+)
+from exo.shared.types.api import (
+    ChatCompletionChoice,
+    ChatCompletionMessage,
+    ChatCompletionResponse,
+    Usage,
+)
+from exo.shared.types.claude_api import (
+    ClaudeContentBlockDeltaEvent,
+    ClaudeContentBlockStartEvent,
+    ClaudeContentBlockStopEvent,
+    ClaudeMessage,
+    ClaudeMessageDelta,
+    ClaudeMessageDeltaEvent,
+    ClaudeMessageDeltaUsage,
+    ClaudeMessagesRequest,
+    ClaudeMessageStart,
+    ClaudeMessageStartEvent,
+    ClaudeMessageStopEvent,
+    ClaudeTextBlock,
+    ClaudeTextDelta,
+    ClaudeUsage,
+)
+
+
+class TestFinishReasonToClaudeStopReason:
+    """Tests for finish_reason to Claude stop_reason mapping."""
+
+    def test_stop_maps_to_end_turn(self):
+        assert finish_reason_to_claude_stop_reason("stop") == "end_turn"
+
+    def test_length_maps_to_max_tokens(self):
+        assert finish_reason_to_claude_stop_reason("length") == "max_tokens"
+
+    def test_tool_calls_maps_to_tool_use(self):
+        assert finish_reason_to_claude_stop_reason("tool_calls") == "tool_use"
+
+    def test_function_call_maps_to_tool_use(self):
+        assert finish_reason_to_claude_stop_reason("function_call") == "tool_use"
+
+    def test_content_filter_maps_to_end_turn(self):
+        assert finish_reason_to_claude_stop_reason("content_filter") == "end_turn"
+
+    def test_none_returns_none(self):
+        assert finish_reason_to_claude_stop_reason(None) is None
+
+
+class TestClaudeRequestToChatParams:
+    """Tests for converting Claude Messages API requests to ChatCompletionTaskParams."""
+
+    def test_basic_request_conversion(self):
+        request = ClaudeMessagesRequest(
+            model="claude-3-opus",
+            max_tokens=100,
+            messages=[
+                ClaudeMessage(role="user", content="Hello"),
+            ],
+        )
+        params = claude_request_to_chat_params(request)
+
+        assert params.model == "claude-3-opus"
+        assert params.max_tokens == 100
+        assert len(params.messages) == 1
+        assert params.messages[0].role == "user"
+        assert params.messages[0].content == "Hello"
+
+    def test_request_with_system_string(self):
+        request = ClaudeMessagesRequest(
+            model="claude-3-opus",
+            max_tokens=100,
+            system="You are a helpful assistant.",
+            messages=[
+                ClaudeMessage(role="user", content="Hello"),
+            ],
+        )
+        params = claude_request_to_chat_params(request)
+
+        assert len(params.messages) == 2
+        assert params.messages[0].role == "system"
+        assert params.messages[0].content == "You are a helpful assistant."
+        assert params.messages[1].role == "user"
+        assert params.messages[1].content == "Hello"
+
+    def test_request_with_system_text_blocks(self):
+        request = ClaudeMessagesRequest(
+            model="claude-3-opus",
+            max_tokens=100,
+            system=[
+                ClaudeTextBlock(text="You are helpful. "),
+                ClaudeTextBlock(text="Be concise."),
+            ],
+            messages=[
+                ClaudeMessage(role="user", content="Hello"),
+            ],
+        )
+        params = claude_request_to_chat_params(request)
+
+        assert len(params.messages) == 2
+        assert params.messages[0].role == "system"
+        assert params.messages[0].content == "You are helpful. Be concise."
+
+    def test_request_with_content_blocks(self):
+        request = ClaudeMessagesRequest(
+            model="claude-3-opus",
+            max_tokens=100,
+            messages=[
+                ClaudeMessage(
+                    role="user",
+                    content=[
+                        ClaudeTextBlock(text="First part. "),
+                        ClaudeTextBlock(text="Second part."),
+                    ],
+                ),
+            ],
+        )
+        params = claude_request_to_chat_params(request)
+
+        assert len(params.messages) == 1
+        assert params.messages[0].content == "First part. Second part."
+
+    def test_request_with_multi_turn_conversation(self):
+        request = ClaudeMessagesRequest(
+            model="claude-3-opus",
+            max_tokens=100,
+            messages=[
+                ClaudeMessage(role="user", content="Hello"),
+                ClaudeMessage(role="assistant", content="Hi there!"),
+                ClaudeMessage(role="user", content="How are you?"),
+            ],
+        )
+        params = claude_request_to_chat_params(request)
+
+        assert len(params.messages) == 3
+        assert params.messages[0].role == "user"
+        assert params.messages[1].role == "assistant"
+        assert params.messages[2].role == "user"
+
+    def test_request_with_optional_parameters(self):
+        request = ClaudeMessagesRequest(
+            model="claude-3-opus",
+            max_tokens=100,
+            messages=[ClaudeMessage(role="user", content="Hello")],
+            temperature=0.7,
+            top_p=0.9,
+            top_k=40,
+            stop_sequences=["STOP", "END"],
+            stream=True,
+        )
+        params = claude_request_to_chat_params(request)
+
+        assert params.temperature == 0.7
+        assert params.top_p == 0.9
+        assert params.top_k == 40
+        assert params.stop == ["STOP", "END"]
+        assert params.stream is True
+
+
+class TestChatResponseToClaudeResponse:
+    """Tests for converting ChatCompletionResponse to Claude Messages API response."""
+
+    def test_basic_response_conversion(self):
+        response = ChatCompletionResponse(
+            id="chatcmpl-123",
+            created=1234567890,
+            model="llama-3.2-1b",
+            choices=[
+                ChatCompletionChoice(
+                    index=0,
+                    message=ChatCompletionMessage(
+                        role="assistant",
+                        content="Hello! How can I help you?",
+                    ),
+                    finish_reason="stop",
+                )
+            ],
+            usage=Usage(prompt_tokens=10, completion_tokens=7, total_tokens=17),
+        )
+        claude_response = chat_response_to_claude_response(response)
+
+        assert claude_response.id == "msg_chatcmpl-123"
+        assert claude_response.model == "llama-3.2-1b"
+        assert claude_response.role == "assistant"
+        assert claude_response.type == "message"
+        assert len(claude_response.content) == 1
+        assert claude_response.content[0].type == "text"
+        assert claude_response.content[0].text == "Hello! How can I help you?"
+        assert claude_response.stop_reason == "end_turn"
+        assert claude_response.usage.input_tokens == 10
+        assert claude_response.usage.output_tokens == 7
+
+    def test_response_with_length_finish_reason(self):
+        response = ChatCompletionResponse(
+            id="chatcmpl-123",
+            created=1234567890,
+            model="llama-3.2-1b",
+            choices=[
+                ChatCompletionChoice(
+                    index=0,
+                    message=ChatCompletionMessage(
+                        role="assistant", content="Truncated..."
+                    ),
+                    finish_reason="length",
+                )
+            ],
+        )
+        claude_response = chat_response_to_claude_response(response)
+
+        assert claude_response.stop_reason == "max_tokens"
+
+    def test_response_with_empty_content(self):
+        response = ChatCompletionResponse(
+            id="chatcmpl-123",
+            created=1234567890,
+            model="llama-3.2-1b",
+            choices=[
+                ChatCompletionChoice(
+                    index=0,
+                    message=ChatCompletionMessage(role="assistant", content=""),
+                    finish_reason="stop",
+                )
+            ],
+            usage=Usage(prompt_tokens=10, completion_tokens=0, total_tokens=10),
+        )
+        claude_response = chat_response_to_claude_response(response)
+
+        assert claude_response.content[0].text == ""
+        assert claude_response.usage.output_tokens == 0
+
+    def test_response_with_no_choices(self):
+        response = ChatCompletionResponse(
+            id="chatcmpl-123",
+            created=1234567890,
+            model="llama-3.2-1b",
+            choices=[],
+        )
+        claude_response = chat_response_to_claude_response(response)
+
+        assert claude_response.content[0].text == ""
+        assert claude_response.stop_reason is None
+        assert claude_response.usage.input_tokens == 0
+        assert claude_response.usage.output_tokens == 0
+
+    def test_response_without_usage(self):
+        """Test response conversion when usage data is not available."""
+        response = ChatCompletionResponse(
+            id="chatcmpl-123",
+            created=1234567890,
+            model="llama-3.2-1b",
+            choices=[
+                ChatCompletionChoice(
+                    index=0,
+                    message=ChatCompletionMessage(role="assistant", content="Hello!"),
+                    finish_reason="stop",
+                )
+            ],
+        )
+        claude_response = chat_response_to_claude_response(response)
+
+        assert claude_response.content[0].text == "Hello!"
+        assert claude_response.usage.input_tokens == 0
+        assert claude_response.usage.output_tokens == 0
+
+
+class TestClaudeMessagesRequestValidation:
+    """Tests for Claude Messages API request validation."""
+
+    def test_request_requires_model(self):
+        with pytest.raises(pydantic.ValidationError):
+            ClaudeMessagesRequest.model_validate(
+                {
+                    "max_tokens": 100,
+                    "messages": [{"role": "user", "content": "Hello"}],
+                }
+            )
+
+    def test_request_requires_max_tokens(self):
+        with pytest.raises(pydantic.ValidationError):
+            ClaudeMessagesRequest.model_validate(
+                {
+                    "model": "claude-3-opus",
+                    "messages": [{"role": "user", "content": "Hello"}],
+                }
+            )
+
+    def test_request_requires_messages(self):
+        with pytest.raises(pydantic.ValidationError):
+            ClaudeMessagesRequest.model_validate(
+                {
+                    "model": "claude-3-opus",
+                    "max_tokens": 100,
+                }
+            )
+
+
+class TestClaudeStreamingEvents:
+    """Tests for Claude Messages API streaming event serialization."""
+
+    def test_message_start_event_format(self):
+        message = ClaudeMessageStart(
+            id="msg_123",
+            model="claude-3-opus",
+            content=[],
+            stop_reason=None,
+            usage=ClaudeUsage(input_tokens=10, output_tokens=0),
+        )
+        event = ClaudeMessageStartEvent(message=message)
+        json_str = event.model_dump_json()
+        parsed = cast(dict[str, Any], json.loads(json_str))
+
+        assert parsed["type"] == "message_start"
+        assert parsed["message"]["id"] == "msg_123"
+        assert parsed["message"]["type"] == "message"
+        assert parsed["message"]["role"] == "assistant"
+        assert parsed["message"]["model"] == "claude-3-opus"
+
+    def test_content_block_start_event_format(self):
+        event = ClaudeContentBlockStartEvent(
+            index=0,
+            content_block=ClaudeTextBlock(text=""),
+        )
+        json_str = event.model_dump_json()
+        parsed = cast(dict[str, Any], json.loads(json_str))
+
+        assert parsed["type"] == "content_block_start"
+        assert parsed["index"] == 0
+        assert parsed["content_block"]["type"] == "text"
+        assert parsed["content_block"]["text"] == ""
+
+    def test_content_block_delta_event_format(self):
+        event = ClaudeContentBlockDeltaEvent(
+            index=0,
+            delta=ClaudeTextDelta(text="Hello"),
+        )
+        json_str = event.model_dump_json()
+        parsed = cast(dict[str, Any], json.loads(json_str))
+
+        assert parsed["type"] == "content_block_delta"
+        assert parsed["index"] == 0
+        assert parsed["delta"]["type"] == "text_delta"
+        assert parsed["delta"]["text"] == "Hello"
+
+    def test_content_block_stop_event_format(self):
+        event = ClaudeContentBlockStopEvent(index=0)
+        json_str = event.model_dump_json()
+        parsed = cast(dict[str, Any], json.loads(json_str))
+
+        assert parsed["type"] == "content_block_stop"
+        assert parsed["index"] == 0
+
+    def test_message_delta_event_format(self):
+        event = ClaudeMessageDeltaEvent(
+            delta=ClaudeMessageDelta(stop_reason="end_turn"),
+            usage=ClaudeMessageDeltaUsage(output_tokens=25),
+        )
+        json_str = event.model_dump_json()
+        parsed = cast(dict[str, Any], json.loads(json_str))
+
+        assert parsed["type"] == "message_delta"
+        assert parsed["delta"]["stop_reason"] == "end_turn"
+        assert parsed["usage"]["output_tokens"] == 25
+
+    def test_message_stop_event_format(self):
+        event = ClaudeMessageStopEvent()
+        json_str = event.model_dump_json()
+        parsed = cast(dict[str, Any], json.loads(json_str))
+
+        assert parsed["type"] == "message_stop"
+
+    def test_sse_format(self):
+        """Test that SSE format is correctly generated."""
+        event = ClaudeContentBlockDeltaEvent(
+            index=0,
+            delta=ClaudeTextDelta(text="Hello"),
+        )
+        # Simulate the SSE format used in the streaming generator
+        sse_line = f"event: content_block_delta\ndata: {event.model_dump_json()}\n\n"
+
+        assert sse_line.startswith("event: content_block_delta\n")
+        assert "data: " in sse_line
+        assert sse_line.endswith("\n\n")

src/exo/master/tests/test_openai_responses_api.py

@@ -0,0 +1,414 @@
+"""Tests for OpenAI Responses API conversion functions and types."""
+
+import json
+from typing import Any, cast
+
+import pydantic
+import pytest
+
+from exo.master.adapters.responses import (
+    chat_response_to_responses_response,
+    responses_request_to_chat_params,
+)
+from exo.shared.types.api import (
+    ChatCompletionChoice,
+    ChatCompletionMessage,
+    ChatCompletionResponse,
+    Usage,
+)
+from exo.shared.types.openai_responses import (
+    ResponseCompletedEvent,
+    ResponseContentPartAddedEvent,
+    ResponseCreatedEvent,
+    ResponseInputMessage,
+    ResponseMessageItem,
+    ResponseOutputItemAddedEvent,
+    ResponseOutputItemDoneEvent,
+    ResponseOutputText,
+    ResponsesRequest,
+    ResponsesResponse,
+    ResponseTextDeltaEvent,
+    ResponseTextDoneEvent,
+    ResponseUsage,
+)
+
+
+class TestResponsesRequestToChatParams:
+    """Tests for converting OpenAI Responses API requests to ChatCompletionTaskParams."""
+
+    def test_string_input_conversion(self):
+        request = ResponsesRequest(
+            model="gpt-4o",
+            input="Hello, how are you?",
+        )
+        params = responses_request_to_chat_params(request)
+
+        assert params.model == "gpt-4o"
+        assert len(params.messages) == 1
+        assert params.messages[0].role == "user"
+        assert params.messages[0].content == "Hello, how are you?"
+
+    def test_message_array_input_conversion(self):
+        request = ResponsesRequest(
+            model="gpt-4o",
+            input=[
+                ResponseInputMessage(role="user", content="Hello"),
+                ResponseInputMessage(role="assistant", content="Hi there!"),
+                ResponseInputMessage(role="user", content="How are you?"),
+            ],
+        )
+        params = responses_request_to_chat_params(request)
+
+        assert len(params.messages) == 3
+        assert params.messages[0].role == "user"
+        assert params.messages[0].content == "Hello"
+        assert params.messages[1].role == "assistant"
+        assert params.messages[1].content == "Hi there!"
+        assert params.messages[2].role == "user"
+        assert params.messages[2].content == "How are you?"
+
+    def test_request_with_instructions(self):
+        request = ResponsesRequest(
+            model="gpt-4o",
+            input="Hello",
+            instructions="You are a helpful assistant. Be concise.",
+        )
+        params = responses_request_to_chat_params(request)
+
+        assert len(params.messages) == 2
+        assert params.messages[0].role == "system"
+        assert params.messages[0].content == "You are a helpful assistant. Be concise."
+        assert params.messages[1].role == "user"
+        assert params.messages[1].content == "Hello"
+
+    def test_request_with_optional_parameters(self):
+        request = ResponsesRequest(
+            model="gpt-4o",
+            input="Hello",
+            max_output_tokens=500,
+            temperature=0.8,
+            top_p=0.95,
+            stream=True,
+        )
+        params = responses_request_to_chat_params(request)
+
+        assert params.max_tokens == 500
+        assert params.temperature == 0.8
+        assert params.top_p == 0.95
+        assert params.stream is True
+
+    def test_request_with_system_role_in_messages(self):
+        request = ResponsesRequest(
+            model="gpt-4o",
+            input=[
+                ResponseInputMessage(role="system", content="Be helpful"),
+                ResponseInputMessage(role="user", content="Hello"),
+            ],
+        )
+        params = responses_request_to_chat_params(request)
+
+        assert len(params.messages) == 2
+        assert params.messages[0].role == "system"
+        assert params.messages[1].role == "user"
+
+    def test_request_with_developer_role(self):
+        request = ResponsesRequest(
+            model="gpt-4o",
+            input=[
+                ResponseInputMessage(role="developer", content="Internal note"),
+                ResponseInputMessage(role="user", content="Hello"),
+            ],
+        )
+        params = responses_request_to_chat_params(request)
+
+        assert len(params.messages) == 2
+        assert params.messages[0].role == "developer"
+
+
+class TestChatResponseToResponsesResponse:
+    """Tests for converting ChatCompletionResponse to OpenAI Responses API response."""
+
+    def test_basic_response_conversion(self):
+        response = ChatCompletionResponse(
+            id="chatcmpl-123",
+            created=1234567890,
+            model="llama-3.2-1b",
+            choices=[
+                ChatCompletionChoice(
+                    index=0,
+                    message=ChatCompletionMessage(
+                        role="assistant",
+                        content="Hello! How can I help you?",
+                    ),
+                    finish_reason="stop",
+                )
+            ],
+        )
+        responses_response = chat_response_to_responses_response(response)
+
+        assert responses_response.id == "resp_chatcmpl-123"
+        assert responses_response.object == "response"
+        assert responses_response.model == "llama-3.2-1b"
+        assert responses_response.status == "completed"
+        assert responses_response.output_text == "Hello! How can I help you?"
+        assert len(responses_response.output) == 1
+        assert responses_response.output[0].type == "message"
+        assert responses_response.output[0].role == "assistant"
+        assert len(responses_response.output[0].content) == 1
+        assert responses_response.output[0].content[0].type == "output_text"
+        assert (
+            responses_response.output[0].content[0].text == "Hello! How can I help you?"
+        )
+
+    def test_response_with_usage(self):
+        response = ChatCompletionResponse(
+            id="chatcmpl-123",
+            created=1234567890,
+            model="llama-3.2-1b",
+            choices=[
+                ChatCompletionChoice(
+                    index=0,
+                    message=ChatCompletionMessage(role="assistant", content="Hello!"),
+                    finish_reason="stop",
+                )
+            ],
+            usage=Usage(
+                prompt_tokens=10,
+                completion_tokens=5,
+                total_tokens=15,
+            ),
+        )
+        responses_response = chat_response_to_responses_response(response)
+
+        assert responses_response.usage is not None
+        assert responses_response.usage.input_tokens == 10
+        assert responses_response.usage.output_tokens == 5
+        assert responses_response.usage.total_tokens == 15
+
+    def test_response_with_empty_content(self):
+        response = ChatCompletionResponse(
+            id="chatcmpl-123",
+            created=1234567890,
+            model="llama-3.2-1b",
+            choices=[
+                ChatCompletionChoice(
+                    index=0,
+                    message=ChatCompletionMessage(role="assistant", content=""),
+                    finish_reason="stop",
+                )
+            ],
+        )
+        responses_response = chat_response_to_responses_response(response)
+
+        assert responses_response.output_text == ""
+        assert responses_response.output[0].content[0].text == ""
+
+    def test_response_with_no_choices(self):
+        response = ChatCompletionResponse(
+            id="chatcmpl-123",
+            created=1234567890,
+            model="llama-3.2-1b",
+            choices=[],
+        )
+        responses_response = chat_response_to_responses_response(response)
+
+        assert responses_response.output_text == ""
+
+    def test_response_without_usage(self):
+        response = ChatCompletionResponse(
+            id="chatcmpl-123",
+            created=1234567890,
+            model="llama-3.2-1b",
+            choices=[
+                ChatCompletionChoice(
+                    index=0,
+                    message=ChatCompletionMessage(role="assistant", content="Hello!"),
+                    finish_reason="stop",
+                )
+            ],
+        )
+        responses_response = chat_response_to_responses_response(response)
+
+        assert responses_response.usage is None
+
+    def test_response_item_id_format(self):
+        response = ChatCompletionResponse(
+            id="chatcmpl-abc123",
+            created=1234567890,
+            model="llama-3.2-1b",
+            choices=[
+                ChatCompletionChoice(
+                    index=0,
+                    message=ChatCompletionMessage(role="assistant", content="Hello!"),
+                    finish_reason="stop",
+                )
+            ],
+        )
+        responses_response = chat_response_to_responses_response(response)
+
+        assert responses_response.output[0].id == "item_chatcmpl-abc123"
+
+
+class TestResponsesRequestValidation:
+    """Tests for OpenAI Responses API request validation."""
+
+    def test_request_requires_model(self):
+        with pytest.raises(pydantic.ValidationError):
+            ResponsesRequest.model_validate(
+                {
+                    "input": "Hello",
+                }
+            )
+
+    def test_request_requires_input(self):
+        with pytest.raises(pydantic.ValidationError):
+            ResponsesRequest.model_validate(
+                {
+                    "model": "gpt-4o",
+                }
+            )
+
+    def test_request_accepts_string_input(self):
+        request = ResponsesRequest(
+            model="gpt-4o",
+            input="Hello",
+        )
+        assert request.input == "Hello"
+
+    def test_request_accepts_message_array_input(self):
+        request = ResponsesRequest(
+            model="gpt-4o",
+            input=[ResponseInputMessage(role="user", content="Hello")],
+        )
+        assert len(request.input) == 1
+
+
+class TestResponsesStreamingEvents:
+    """Tests for OpenAI Responses API streaming event serialization."""
+
+    def test_response_created_event_format(self):
+        response = ResponsesResponse(
+            id="resp_123",
+            model="gpt-4o",
+            status="in_progress",
+            output=[],
+            output_text="",
+        )
+        event = ResponseCreatedEvent(response=response)
+        json_str = event.model_dump_json()
+        parsed = cast(dict[str, Any], json.loads(json_str))
+
+        assert parsed["type"] == "response.created"
+        assert parsed["response"]["id"] == "resp_123"
+        assert parsed["response"]["object"] == "response"
+        assert parsed["response"]["status"] == "in_progress"
+
+    def test_output_item_added_event_format(self):
+        item = ResponseMessageItem(
+            id="item_123",
+            content=[ResponseOutputText(text="")],
+            status="in_progress",
+        )
+        event = ResponseOutputItemAddedEvent(output_index=0, item=item)
+        json_str = event.model_dump_json()
+        parsed = cast(dict[str, Any], json.loads(json_str))
+
+        assert parsed["type"] == "response.output_item.added"
+        assert parsed["output_index"] == 0
+        assert parsed["item"]["type"] == "message"
+        assert parsed["item"]["id"] == "item_123"
+        assert parsed["item"]["role"] == "assistant"
+
+    def test_content_part_added_event_format(self):
+        part = ResponseOutputText(text="")
+        event = ResponseContentPartAddedEvent(
+            output_index=0,
+            content_index=0,
+            part=part,
+        )
+        json_str = event.model_dump_json()
+        parsed = cast(dict[str, Any], json.loads(json_str))
+
+        assert parsed["type"] == "response.content_part.added"
+        assert parsed["output_index"] == 0
+        assert parsed["content_index"] == 0
+        assert parsed["part"]["type"] == "output_text"
+
+    def test_text_delta_event_format(self):
+        event = ResponseTextDeltaEvent(
+            output_index=0,
+            content_index=0,
+            delta="Hello",
+        )
+        json_str = event.model_dump_json()
+        parsed = cast(dict[str, Any], json.loads(json_str))
+
+        assert parsed["type"] == "response.output_text.delta"
+        assert parsed["output_index"] == 0
+        assert parsed["content_index"] == 0
+        assert parsed["delta"] == "Hello"
+
+    def test_text_done_event_format(self):
+        event = ResponseTextDoneEvent(
+            output_index=0,
+            content_index=0,
+            text="Hello, world!",
+        )
+        json_str = event.model_dump_json()
+        parsed = cast(dict[str, Any], json.loads(json_str))
+
+        assert parsed["type"] == "response.output_text.done"
+        assert parsed["text"] == "Hello, world!"
+
+    def test_output_item_done_event_format(self):
+        item = ResponseMessageItem(
+            id="item_123",
+            content=[ResponseOutputText(text="Hello, world!")],
+            status="completed",
+        )
+        event = ResponseOutputItemDoneEvent(output_index=0, item=item)
+        json_str = event.model_dump_json()
+        parsed = cast(dict[str, Any], json.loads(json_str))
+
+        assert parsed["type"] == "response.output_item.done"
+        assert parsed["item"]["status"] == "completed"
+        assert parsed["item"]["content"][0]["text"] == "Hello, world!"
+
+    def test_response_completed_event_format(self):
+        item = ResponseMessageItem(
+            id="item_123",
+            content=[ResponseOutputText(text="Hello!")],
+            status="completed",
+        )
+        response = ResponsesResponse(
+            id="resp_123",
+            model="gpt-4o",
+            status="completed",
+            output=[item],
+            output_text="Hello!",
+            usage=ResponseUsage(input_tokens=10, output_tokens=5, total_tokens=15),
+        )
+        event = ResponseCompletedEvent(response=response)
+        json_str = event.model_dump_json()
+        parsed = cast(dict[str, Any], json.loads(json_str))
+
+        assert parsed["type"] == "response.completed"
+        assert parsed["response"]["status"] == "completed"
+        assert parsed["response"]["output_text"] == "Hello!"
+        assert parsed["response"]["usage"]["total_tokens"] == 15
+
+    def test_sse_format(self):
+        """Test that SSE format is correctly generated."""
+        event = ResponseTextDeltaEvent(
+            output_index=0,
+            content_index=0,
+            delta="Hello",
+        )
+        # Simulate the SSE format used in the streaming generator
+        sse_line = (
+            f"event: response.output_text.delta\ndata: {event.model_dump_json()}\n\n"
+        )
+
+        assert sse_line.startswith("event: response.output_text.delta\n")
+        assert "data: " in sse_line
+        assert sse_line.endswith("\n\n")

src/exo/shared/types/api.py

@@ -146,10 +146,12 @@ class ChatCompletionTaskParams(BaseModel):
     stream: bool = False
     temperature: float | None = None
     top_p: float | None = None
+    top_k: int | None = None
     tools: list[dict[str, Any]] | None = None
     tool_choice: str | dict[str, Any] | None = None
     parallel_tool_calls: bool | None = None
     user: str | None = None
+    continue_from_prefix: bool = False  # When True, continue the last assistant message
 
 
 class BenchChatCompletionTaskParams(ChatCompletionTaskParams):

src/exo/shared/types/chunks.py

@@ -1,6 +1,6 @@
 from enum import Enum
 
-from exo.shared.types.api import GenerationStats
+from exo.shared.types.api import GenerationStats, TopLogprobItem
 from exo.utils.pydantic_ext import TaggedModel
 
 from .api import FinishReason
@@ -20,6 +20,8 @@ class BaseChunk(TaggedModel):
 class TokenChunk(BaseChunk):
     text: str
     token_id: int
+    logprob: float | None = None  # Log probability of the selected token
+    top_logprobs: list[TopLogprobItem] | None = None  # Top-k alternative tokens
     finish_reason: FinishReason | None = None
     stats: GenerationStats | None = None
 

src/exo/shared/types/claude_api.py

@@ -0,0 +1,168 @@
+"""Claude Messages API types for request/response conversion."""
+
+from typing import Literal
+
+from pydantic import BaseModel, Field
+
+# Type aliases
+ClaudeRole = Literal["user", "assistant"]
+ClaudeStopReason = Literal["end_turn", "max_tokens", "stop_sequence", "tool_use"]
+
+
+# Content block types
+class ClaudeTextBlock(BaseModel, frozen=True):
+    """Text content block in Claude Messages API."""
+
+    type: Literal["text"] = "text"
+    text: str
+
+
+class ClaudeImageSource(BaseModel, frozen=True):
+    """Image source for Claude image blocks."""
+
+    type: Literal["base64", "url"]
+    media_type: str | None = None
+    data: str | None = None
+    url: str | None = None
+
+
+class ClaudeImageBlock(BaseModel, frozen=True):
+    """Image content block in Claude Messages API."""
+
+    type: Literal["image"] = "image"
+    source: ClaudeImageSource
+
+
+ClaudeContentBlock = ClaudeTextBlock | ClaudeImageBlock
+
+
+# Request types
+class ClaudeMessage(BaseModel, frozen=True):
+    """Message in Claude Messages API request."""
+
+    role: ClaudeRole
+    content: str | list[ClaudeContentBlock]
+
+
+class ClaudeMessagesRequest(BaseModel):
+    """Request body for Claude Messages API."""
+
+    model: str
+    max_tokens: int
+    messages: list[ClaudeMessage]
+    system: str | list[ClaudeTextBlock] | None = None
+    stop_sequences: list[str] | None = None
+    stream: bool = False
+    temperature: float | None = None
+    top_p: float | None = None
+    top_k: int | None = None
+    metadata: dict[str, str] | None = None
+
+
+# Response types
+class ClaudeUsage(BaseModel, frozen=True):
+    """Token usage in Claude Messages API response."""
+
+    input_tokens: int
+    output_tokens: int
+
+
+class ClaudeMessagesResponse(BaseModel, frozen=True):
+    """Response body for Claude Messages API."""
+
+    id: str
+    type: Literal["message"] = "message"
+    role: Literal["assistant"] = "assistant"
+    content: list[ClaudeTextBlock]
+    model: str
+    stop_reason: ClaudeStopReason | None = None
+    stop_sequence: str | None = None
+    usage: ClaudeUsage
+
+
+# Streaming event types
+class ClaudeMessageStart(BaseModel, frozen=True):
+    """Partial message in message_start event."""
+
+    id: str
+    type: Literal["message"] = "message"
+    role: Literal["assistant"] = "assistant"
+    content: list[ClaudeTextBlock] = Field(default_factory=list)
+    model: str
+    stop_reason: ClaudeStopReason | None = None
+    stop_sequence: str | None = None
+    usage: ClaudeUsage
+
+
+class ClaudeMessageStartEvent(BaseModel, frozen=True):
+    """Event sent at start of message stream."""
+
+    type: Literal["message_start"] = "message_start"
+    message: ClaudeMessageStart
+
+
+class ClaudeContentBlockStartEvent(BaseModel, frozen=True):
+    """Event sent at start of a content block."""
+
+    type: Literal["content_block_start"] = "content_block_start"
+    index: int
+    content_block: ClaudeTextBlock
+
+
+class ClaudeTextDelta(BaseModel, frozen=True):
+    """Delta for text content block."""
+
+    type: Literal["text_delta"] = "text_delta"
+    text: str
+
+
+class ClaudeContentBlockDeltaEvent(BaseModel, frozen=True):
+    """Event sent for content block delta."""
+
+    type: Literal["content_block_delta"] = "content_block_delta"
+    index: int
+    delta: ClaudeTextDelta
+
+
+class ClaudeContentBlockStopEvent(BaseModel, frozen=True):
+    """Event sent at end of a content block."""
+
+    type: Literal["content_block_stop"] = "content_block_stop"
+    index: int
+
+
+class ClaudeMessageDeltaUsage(BaseModel, frozen=True):
+    """Usage in message_delta event."""
+
+    output_tokens: int
+
+
+class ClaudeMessageDelta(BaseModel, frozen=True):
+    """Delta in message_delta event."""
+
+    stop_reason: ClaudeStopReason | None = None
+    stop_sequence: str | None = None
+
+
+class ClaudeMessageDeltaEvent(BaseModel, frozen=True):
+    """Event sent with final message delta."""
+
+    type: Literal["message_delta"] = "message_delta"
+    delta: ClaudeMessageDelta
+    usage: ClaudeMessageDeltaUsage
+
+
+class ClaudeMessageStopEvent(BaseModel, frozen=True):
+    """Event sent at end of message stream."""
+
+    type: Literal["message_stop"] = "message_stop"
+
+
+ClaudeStreamEvent = (
+    ClaudeMessageStartEvent
+    | ClaudeContentBlockStartEvent
+    | ClaudeContentBlockDeltaEvent
+    | ClaudeContentBlockStopEvent
+    | ClaudeMessageDeltaEvent
+    | ClaudeMessageStopEvent
+)

src/exo/shared/types/openai_responses.py

@@ -0,0 +1,162 @@
+"""OpenAI Responses API types for request/response conversion."""
+
+import time
+from typing import Literal
+
+from pydantic import BaseModel, Field
+
+# Type aliases
+ResponseStatus = Literal["completed", "failed", "in_progress", "incomplete"]
+ResponseRole = Literal["user", "assistant", "system", "developer"]
+
+
+# Request types
+class ResponseInputMessage(BaseModel, frozen=True):
+    """Input message for Responses API."""
+
+    role: ResponseRole
+    content: str
+
+
+class ResponsesRequest(BaseModel):
+    """Request body for OpenAI Responses API."""
+
+    model: str
+    input: str | list[ResponseInputMessage]
+    instructions: str | None = None
+    max_output_tokens: int | None = None
+    temperature: float | None = None
+    top_p: float | None = None
+    stream: bool = False
+    # previous_response_id not supported in MVP
+    metadata: dict[str, str] | None = None
+
+
+# Response types
+class ResponseOutputText(BaseModel, frozen=True):
+    """Text content in response output."""
+
+    type: Literal["output_text"] = "output_text"
+    text: str
+    annotations: list[dict[str, str]] = Field(default_factory=list)
+
+
+class ResponseMessageItem(BaseModel, frozen=True):
+    """Message item in response output array."""
+
+    type: Literal["message"] = "message"
+    id: str
+    role: Literal["assistant"] = "assistant"
+    content: list[ResponseOutputText]
+    status: ResponseStatus = "completed"
+
+
+ResponseItem = ResponseMessageItem  # Can expand for function_call, reasoning, etc.
+
+
+class ResponseUsage(BaseModel, frozen=True):
+    """Token usage in Responses API response."""
+
+    input_tokens: int
+    output_tokens: int
+    total_tokens: int
+
+
+class ResponsesResponse(BaseModel, frozen=True):
+    """Response body for OpenAI Responses API."""
+
+    id: str
+    object: Literal["response"] = "response"
+    created_at: int = Field(default_factory=lambda: int(time.time()))
+    status: ResponseStatus = "completed"
+    model: str
+    output: list[ResponseItem]
+    output_text: str
+    usage: ResponseUsage | None = None
+
+
+# Streaming event types
+class ResponseCreatedEvent(BaseModel, frozen=True):
+    """Event sent when response is created."""
+
+    type: Literal["response.created"] = "response.created"
+    response: ResponsesResponse
+
+
+class ResponseInProgressEvent(BaseModel, frozen=True):
+    """Event sent when response starts processing."""
+
+    type: Literal["response.in_progress"] = "response.in_progress"
+    response: ResponsesResponse
+
+
+class ResponseOutputItemAddedEvent(BaseModel, frozen=True):
+    """Event sent when an output item is added."""
+
+    type: Literal["response.output_item.added"] = "response.output_item.added"
+    output_index: int
+    item: ResponseItem
+
+
+class ResponseContentPartAddedEvent(BaseModel, frozen=True):
+    """Event sent when a content part is added."""
+
+    type: Literal["response.content_part.added"] = "response.content_part.added"
+    output_index: int
+    content_index: int
+    part: ResponseOutputText
+
+
+class ResponseTextDeltaEvent(BaseModel, frozen=True):
+    """Event sent for text delta during streaming."""
+
+    type: Literal["response.output_text.delta"] = "response.output_text.delta"
+    output_index: int
+    content_index: int
+    delta: str
+
+
+class ResponseTextDoneEvent(BaseModel, frozen=True):
+    """Event sent when text content is done."""
+
+    type: Literal["response.output_text.done"] = "response.output_text.done"
+    output_index: int
+    content_index: int
+    text: str
+
+
+class ResponseContentPartDoneEvent(BaseModel, frozen=True):
+    """Event sent when a content part is done."""
+
+    type: Literal["response.content_part.done"] = "response.content_part.done"
+    output_index: int
+    content_index: int
+    part: ResponseOutputText
+
+
+class ResponseOutputItemDoneEvent(BaseModel, frozen=True):
+    """Event sent when an output item is done."""
+
+    type: Literal["response.output_item.done"] = "response.output_item.done"
+    output_index: int
+    item: ResponseItem
+
+
+class ResponseCompletedEvent(BaseModel, frozen=True):
+    """Event sent when response is completed."""
+
+    type: Literal["response.completed"] = "response.completed"
+    response: ResponsesResponse
+
+
+ResponsesStreamEvent = (
+    ResponseCreatedEvent
+    | ResponseInProgressEvent
+    | ResponseOutputItemAddedEvent
+    | ResponseContentPartAddedEvent
+    | ResponseTextDeltaEvent
+    | ResponseTextDoneEvent
+    | ResponseContentPartDoneEvent
+    | ResponseOutputItemDoneEvent
+    | ResponseCompletedEvent
+)

src/exo/shared/types/worker/runner_response.py

@@ -1,4 +1,4 @@
-from exo.shared.types.api import FinishReason, GenerationStats
+from exo.shared.types.api import FinishReason, GenerationStats, TopLogprobItem
 from exo.utils.pydantic_ext import TaggedModel
 
 
@@ -13,7 +13,8 @@ class TokenizedResponse(BaseRunnerResponse):
 class GenerationResponse(BaseRunnerResponse):
     text: str
     token: int
-    # logprobs: list[float] | None = None # too big. we can change to be top-k
+    logprob: float | None = None  # Log probability of the selected token
+    top_logprobs: list[TopLogprobItem] | None = None  # Top-k alternative tokens
     finish_reason: FinishReason | None = None
     stats: GenerationStats | None = None
 

src/exo/worker/engines/mlx/__init__.py

@@ -40,4 +40,6 @@ class TokenizerWrapper:
         messages_dicts: list[dict[str, Any]],
         tokenize: bool = False,
         add_generation_prompt: bool = True,
+        continue_final_message: bool = False,
+        tools: list[dict[str, Any]] | None = None,
     ) -> str: ...

src/exo/worker/engines/mlx/generator/generate.py

@@ -12,6 +12,7 @@ from exo.shared.types.api import (
     ChatCompletionMessage,
     FinishReason,
     GenerationStats,
+    TopLogprobItem,
 )
 from exo.shared.types.memory import Memory
 from exo.shared.types.tasks import ChatCompletionTaskParams
@@ -115,6 +116,60 @@ def eos_ids_from_tokenizer(tokenizer: TokenizerWrapper) -> list[int]:
     return eos
 
 
+def extract_top_logprobs(
+    logprobs: mx.array,
+    tokenizer: TokenizerWrapper,
+    top_k: int,
+    selected_token: int,
+) -> tuple[float, list[TopLogprobItem]]:
+    """Extract the selected token's logprob and top-k alternative tokens.
+
+    Args:
+        logprobs: Full vocabulary logprobs array from MLX
+        tokenizer: Tokenizer for decoding token IDs to strings
+        top_k: Number of top alternatives to return
+        selected_token: The token ID that was actually sampled
+
+    Returns:
+        Tuple of (selected_token_logprob, list of TopLogprobItem for top-k tokens)
+    """
+    # Get the logprob of the selected token
+    selected_logprob = float(logprobs[selected_token].item())
+
+    # Get top-k indices (most probable tokens)
+    # mx.argpartition gives indices that would partition the array
+    # We negate logprobs since argpartition finds smallest, and we want largest
+    top_k = min(top_k, logprobs.shape[0])  # Don't exceed vocab size
+    top_indices = mx.argpartition(-logprobs, top_k)[:top_k]
+
+    # Get the actual logprob values for these indices
+    top_values = logprobs[top_indices]
+
+    # Sort by logprob (descending) for consistent ordering
+    sort_order = mx.argsort(-top_values)
+    top_indices = top_indices[sort_order]
+    top_values = top_values[sort_order]
+
+    # Convert to list of TopLogprobItem
+    top_logprob_items: list[TopLogprobItem] = []
+    for i in range(top_k):
+        token_id = int(top_indices[i].item())
+        token_logprob = float(top_values[i].item())
+        # Decode token ID to string
+        token_str = tokenizer.decode([token_id])
+        # Get byte representation
+        token_bytes = list(token_str.encode("utf-8"))
+        top_logprob_items.append(
+            TopLogprobItem(
+                token=token_str,
+                logprob=token_logprob,
+                bytes=token_bytes,
+            )
+        )
+
+    return selected_logprob, top_logprob_items
+
+
 def mlx_generate(
     model: Model,
     tokenizer: TokenizerWrapper,
@@ -146,9 +201,24 @@ def mlx_generate(
     sampler = make_sampler(
         temp=task.temperature if task.temperature is not None else 0.7,
         top_p=task.top_p if task.top_p is not None else 1.0,
+        top_k=task.top_k if task.top_k is not None else 0,
     )
 
+    # Normalize stop sequences to a list
+    stop_sequences: list[str] = (
+        ([task.stop] if isinstance(task.stop, str) else task.stop)
+        if task.stop is not None
+        else []
+    )
+    max_stop_len = max((len(s) for s in stop_sequences), default=0)
+
     max_tokens = task.max_tokens or MAX_TOKENS
+    accumulated_text = ""
+
+    # Determine if we need to extract logprobs
+    should_extract_logprobs = task.logprobs is True
+    num_top_logprobs = task.top_logprobs if task.top_logprobs is not None else 5
+
     for out in stream_generate(
         model=model,
         tokenizer=tokenizer,
@@ -163,9 +233,41 @@ def mlx_generate(
         kv_bits=KV_BITS,
     ):
         logger.info(out.text)
+        accumulated_text += out.text
 
+        # Check for stop sequences
+        text = out.text
+        finish_reason: FinishReason | None = cast(
+            FinishReason | None, out.finish_reason
+        )
+        stop_matched = False
+
+        if stop_sequences:
+            for stop_seq in stop_sequences:
+                if stop_seq in accumulated_text:
+                    # Trim text to just before the stop sequence
+                    stop_index = accumulated_text.find(stop_seq)
+                    text_before_stop = accumulated_text[:stop_index]
+                    chunk_start = len(accumulated_text) - len(out.text)
+                    text = text_before_stop[chunk_start:]
+                    finish_reason = "stop"
+                    stop_matched = True
+                    break
+
+        # Extract logprobs if requested
+        token_logprob: float | None = None
+        top_logprobs: list[TopLogprobItem] | None = None
+        if should_extract_logprobs:
+            token_logprob, top_logprobs = extract_top_logprobs(
+                logprobs=out.logprobs,
+                tokenizer=tokenizer,
+                top_k=num_top_logprobs,
+                selected_token=out.token,
+            )
+
+        is_done = finish_reason is not None
         stats: GenerationStats | None = None
-        if out.finish_reason is not None:
+        if is_done:
             stats = GenerationStats(
                 prompt_tps=float(out.prompt_tps),
                 generation_tps=float(out.generation_tps),
@@ -173,22 +275,25 @@ def mlx_generate(
                 generation_tokens=int(out.generation_tokens),
                 peak_memory_usage=Memory.from_gb(out.peak_memory),
             )
-
-            if out.finish_reason not in get_args(FinishReason):
-                # We don't throw here as this failure case is really not all that bad
-                # Just log the error and move on
+            if not stop_matched and out.finish_reason not in get_args(FinishReason):
                 logger.warning(
                     f"Model generated unexpected finish_reason: {out.finish_reason}"
                 )
 
         yield GenerationResponse(
-            text=out.text,
+            text=text,
             token=out.token,
-            finish_reason=cast(FinishReason | None, out.finish_reason),
+            logprob=token_logprob,
+            top_logprobs=top_logprobs,
+            finish_reason=finish_reason,
             stats=stats,
         )
 
-        if out.finish_reason is not None:
+        if is_done:
             break
 
+        # Limit accumulated_text to what's needed for stop sequence detection
+        if max_stop_len > 0 and len(accumulated_text) > max_stop_len:
+            accumulated_text = accumulated_text[-max_stop_len:]
+
         # TODO: Do we want an mx_barrier?

src/exo/worker/engines/mlx/utils_mlx.py

@@ -359,12 +359,26 @@ def apply_chat_template(
             {k: v for k, v in message.model_dump().items() if v is not None}  # type: ignore
         )
 
-    prompt: str = tokenizer.apply_chat_template(
-        formatted_messages,
-        tokenize=False,
-        add_generation_prompt=True,
-        tools=chat_task_data.tools,
-    )
+    # Use continue_final_message when continuing from prefix (e.g., regenerate from token)
+    # This keeps the final assistant message open without EOS tokens
+    # Note: explicitly set add_generation_prompt=False when using continue_final_message
+    # because some tokenizers (e.g., Kimi) default add_generation_prompt=True
+    prompt: str
+    if chat_task_data.continue_from_prefix:
+        prompt = tokenizer.apply_chat_template(
+            formatted_messages,
+            tokenize=False,
+            continue_final_message=True,
+            add_generation_prompt=False,
+            tools=chat_task_data.tools,
+        )
+    else:
+        prompt = tokenizer.apply_chat_template(
+            formatted_messages,
+            tokenize=False,
+            add_generation_prompt=True,
+            tools=chat_task_data.tools,
+        )
 
     logger.info(prompt)
 

src/exo/worker/runner/runner.py

@@ -186,6 +186,8 @@ def main(
                                                 model=shard_metadata.model_meta.model_id,
                                                 text=response.text,
                                                 token_id=response.token,
+                                                logprob=response.logprob,
+                                                top_logprobs=response.top_logprobs,
                                                 finish_reason=response.finish_reason,
                                                 stats=response.stats,
                                             ),