Add artifact message persistence for session reconstruction

- Add ArtifactMessage type as core part of AppMessage union (not CustomMessages)
- ArtifactsRuntimeProvider appends artifact messages on create/update/delete
- MessageList filters out artifact messages (UI display only)
- artifacts.ts reconstructFromMessages handles artifact messages
- Export ARTIFACTS_RUNTIME_PROVIDER_DESCRIPTION from main index
- Fix artifact creation bug: pass filename as title instead of mimeType

Changes:
- web-ui/src/components/Messages.ts: Add ArtifactMessage to BaseMessage union
- web-ui/src/components/MessageList.ts: Skip artifact messages in render
- web-ui/src/components/sandbox/ArtifactsRuntimeProvider.ts: Append messages, fix title parameter
- web-ui/src/ChatPanel.ts: Pass agent.appendMessage callback
- web-ui/src/tools/artifacts/artifacts.ts: Handle artifact messages in reconstructFromMessages
- web-ui/src/index.ts: Export ARTIFACTS_RUNTIME_PROVIDER_DESCRIPTION
- web-ui/example/src/custom-messages.ts: Update message transformer to filter artifacts

packages/web-ui/example/src/custom-messages.ts

@@ -78,6 +78,11 @@ export function createSystemNotification(
 export function customMessageTransformer(messages: AppMessage[]): Message[] {
 	return messages
 		.filter((m) => {
+			// Filter out artifact messages - they're for session reconstruction only
+			if (m.role === "artifact") {
+				return false;
+			}
+
 			// Keep LLM-compatible messages + custom messages
 			return (
 				m.role === "user" ||

packages/web-ui/example/src/main.ts

@@ -194,7 +194,11 @@ Feel free to use these tools when needed to provide accurate and helpful respons
 		}
 	});
 
-	await chatPanel.setAgent(agent);
+	await chatPanel.setAgent(agent, {
+		onApiKeyRequired: async (provider: string) => {
+			return await ApiKeyPromptDialog.prompt(provider);
+		}
+	});
 };
 
 const loadSession = async (sessionId: string): Promise<boolean> => {
@@ -377,9 +381,6 @@ async function initApp() {
 
 	// Create ChatPanel
 	chatPanel = new ChatPanel();
-	chatPanel.onApiKeyRequired = async (provider: string) => {
-		return await ApiKeyPromptDialog.prompt(provider);
-	};
 
 	// Check for session in URL
 	const urlParams = new URLSearchParams(window.location.search);

packages/web-ui/src/ChatPanel.ts

@@ -1,9 +1,11 @@
 import { Badge, html } from "@mariozechner/mini-lit";
 import { LitElement } from "lit";
-import { customElement, property, state } from "lit/decorators.js";
+import { customElement, state } from "lit/decorators.js";
 import type { Agent } from "./agent/agent.js";
 import "./components/AgentInterface.js";
+import type { AgentTool } from "@mariozechner/pi-ai";
 import type { AgentInterface } from "./components/AgentInterface.js";
+import { ArtifactsRuntimeProvider } from "./components/sandbox/ArtifactsRuntimeProvider.js";
 import { AttachmentsRuntimeProvider } from "./components/sandbox/AttachmentsRuntimeProvider.js";
 import type { SandboxRuntimeProvider } from "./components/sandbox/SandboxRuntimeProvider.js";
 import { ArtifactsPanel, ArtifactsToolRenderer } from "./tools/artifacts/index.js";
@@ -23,25 +25,6 @@ export class ChatPanel extends LitElement {
 	@state() private artifactCount = 0;
 	@state() private showArtifactsPanel = false;
 	@state() private windowWidth = 0;
-	@property({ attribute: false }) runtimeProvidersFactory = () => {
-		const attachments: Attachment[] = [];
-		for (const message of this.agent!.state.messages) {
-			if (message.role === "user") {
-				message.attachments?.forEach((a) => {
-					attachments.push(a);
-				});
-			}
-		}
-		const providers: SandboxRuntimeProvider[] = [];
-		if (attachments.length > 0) {
-			providers.push(new AttachmentsRuntimeProvider(attachments));
-		}
-		return providers;
-	};
-	@property({ attribute: false }) sandboxUrlProvider?: () => string;
-	@property({ attribute: false }) onApiKeyRequired?: (provider: string) => Promise<boolean>;
-	@property({ attribute: false }) onBeforeSend?: () => void | Promise<void>;
-	@property({ attribute: false }) additionalTools?: any[];
 
 	private resizeHandler = () => {
 		this.windowWidth = window.innerWidth;
@@ -72,7 +55,19 @@ export class ChatPanel extends LitElement {
 		window.removeEventListener("resize", this.resizeHandler);
 	}
 
-	async setAgent(agent: Agent) {
+	async setAgent(
+		agent: Agent,
+		config?: {
+			onApiKeyRequired?: (provider: string) => Promise<boolean>;
+			onBeforeSend?: () => void | Promise<void>;
+			sandboxUrlProvider?: () => string;
+			toolsFactory?: (
+				agent: Agent,
+				agentInterface: AgentInterface,
+				artifactsPanel: ArtifactsPanel,
+			) => AgentTool<any>[];
+		},
+	) {
 		this.agent = agent;
 
 		// Create AgentInterface
@@ -82,26 +77,74 @@ export class ChatPanel extends LitElement {
 		this.agentInterface.enableModelSelector = true;
 		this.agentInterface.enableThinkingSelector = true;
 		this.agentInterface.showThemeToggle = false;
-		this.agentInterface.onApiKeyRequired = this.onApiKeyRequired;
+		this.agentInterface.onApiKeyRequired = config?.onApiKeyRequired;
-		this.agentInterface.onBeforeSend = this.onBeforeSend;
+		this.agentInterface.onBeforeSend = config?.onBeforeSend;
 
 		// Create JavaScript REPL tool
 		const javascriptReplTool = createJavaScriptReplTool();
-		if (this.sandboxUrlProvider) {
+		if (config?.sandboxUrlProvider) {
-			javascriptReplTool.sandboxUrlProvider = this.sandboxUrlProvider;
+			javascriptReplTool.sandboxUrlProvider = config.sandboxUrlProvider;
 		}
 
 		// Set up artifacts panel
 		this.artifactsPanel = new ArtifactsPanel();
-		if (this.sandboxUrlProvider) {
+		if (config?.sandboxUrlProvider) {
-			this.artifactsPanel.sandboxUrlProvider = this.sandboxUrlProvider;
+			this.artifactsPanel.sandboxUrlProvider = config.sandboxUrlProvider;
 		}
 		// Register the standalone tool renderer (not the panel itself)
 		registerToolRenderer("artifacts", new ArtifactsToolRenderer(this.artifactsPanel));
 
 		// Runtime providers factory
-		javascriptReplTool.runtimeProvidersFactory = this.runtimeProvidersFactory;
+		const runtimeProvidersFactory = () => {
-		this.artifactsPanel.runtimeProvidersFactory = this.runtimeProvidersFactory;
+			const attachments: Attachment[] = [];
+			for (const message of this.agent!.state.messages) {
+				if (message.role === "user") {
+					message.attachments?.forEach((a) => {
+						attachments.push(a);
+					});
+				}
+			}
+			const providers: SandboxRuntimeProvider[] = [];
+
+			// Add attachments provider if there are attachments
+			if (attachments.length > 0) {
+				providers.push(new AttachmentsRuntimeProvider(attachments));
+			}
+
+			// Add artifacts provider (always available)
+			providers.push(
+				new ArtifactsRuntimeProvider(
+					() => this.artifactsPanel!.artifacts,
+					async (filename: string, content: string) => {
+						await this.artifactsPanel!.tool.execute("", {
+							command: "create",
+							filename,
+							content,
+						});
+					},
+					async (filename: string, content: string) => {
+						await this.artifactsPanel!.tool.execute("", {
+							command: "rewrite",
+							filename,
+							content,
+						});
+					},
+					async (filename: string) => {
+						await this.artifactsPanel!.tool.execute("", {
+							command: "delete",
+							filename,
+						});
+					},
+					(message: any) => {
+						this.agent!.appendMessage(message);
+					},
+				),
+			);
+
+			return providers;
+		};
+		javascriptReplTool.runtimeProvidersFactory = runtimeProvidersFactory;
+		this.artifactsPanel.runtimeProvidersFactory = runtimeProvidersFactory;
 
 		this.artifactsPanel.onArtifactsChange = () => {
 			const count = this.artifactsPanel?.artifacts?.size ?? 0;
@@ -125,7 +168,8 @@ export class ChatPanel extends LitElement {
 		};
 
 		// Set tools on the agent
-		const tools = [javascriptReplTool, this.artifactsPanel.tool, ...(this.additionalTools || [])];
+		const additionalTools = config?.toolsFactory?.(agent, this.agentInterface, this.artifactsPanel) || [];
+		const tools = [javascriptReplTool, this.artifactsPanel.tool, ...additionalTools];
 		this.agent.setTools(tools);
 
 		// Reconstruct artifacts from existing messages

packages/web-ui/src/agent/agent.ts

@@ -293,10 +293,10 @@ export class Agent {
 			this.patch({ isStreaming: false, streamMessage: null, pendingToolCalls: new Set<string>() });
 			this.abortController = undefined;
 		}
-		/*{
+		{
 			const { systemPrompt, model, messages } = this._state;
 			console.log("final state:", { systemPrompt, model, messages });
-		}*/
+		}
 	}
 
 	private patch(p: Partial<AgentState>): void {

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

@@ -37,6 +37,11 @@ export class MessageList extends LitElement {
 		const items: Array<{ key: string; template: TemplateResult }> = [];
 		let index = 0;
 		for (const msg of this.messages) {
+			// Skip artifact messages - they're for session persistence only, not UI display
+			if (msg.role === "artifact") {
+				continue;
+			}
+
 			// Try custom renderer first
 			const customTemplate = renderMessage(msg);
 			if (customTemplate) {

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

@@ -15,8 +15,18 @@ import { i18n } from "../utils/i18n.js";
 
 export type UserMessageWithAttachments = UserMessageType & { attachments?: Attachment[] };
 
+// Artifact message type for session persistence
+export interface ArtifactMessage {
+	role: "artifact";
+	action: "create" | "update" | "delete";
+	filename: string;
+	content?: string;
+	title?: string;
+	timestamp: string;
+}
+
 // Base message union
-type BaseMessage = AssistantMessageType | UserMessageWithAttachments | ToolResultMessageType;
+type BaseMessage = AssistantMessageType | UserMessageWithAttachments | ToolResultMessageType | ArtifactMessage;
 
 // Extensible interface - apps can extend via declaration merging
 // Example:

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

@@ -169,7 +169,7 @@ export class SandboxIframe extends LitElement {
 		return new Promise((resolve, reject) => {
 			// 4. Create execution consumer for lifecycle messages
 			const executionConsumer: MessageConsumer = {
-				handleMessage(message: any): boolean {
+				async handleMessage(message: any): Promise<boolean> {
 					if (message.type === "console") {
 						logs.push({
 							type: message.method === "error" ? "error" : "log",

packages/web-ui/src/components/sandbox/ArtifactsRuntimeProvider.ts

@@ -0,0 +1,232 @@
+import { ARTIFACTS_RUNTIME_PROVIDER_DESCRIPTION } from "../../prompts/tool-prompts.js";
+import type { SandboxRuntimeProvider } from "./SandboxRuntimeProvider.js";
+
+/**
+ * Artifacts Runtime Provider
+ *
+ * Provides programmatic access to session artifacts from sandboxed code.
+ * Allows code to create, read, update, and delete artifacts dynamically.
+ */
+export class ArtifactsRuntimeProvider implements SandboxRuntimeProvider {
+	constructor(
+		private getArtifactsFn: () => Map<string, { content: string }>,
+		private createArtifactFn: (filename: string, content: string, title?: string) => Promise<void>,
+		private updateArtifactFn: (filename: string, content: string, title?: string) => Promise<void>,
+		private deleteArtifactFn: (filename: string) => Promise<void>,
+		private appendMessageFn?: (message: any) => void,
+	) {}
+
+	getData(): Record<string, any> {
+		// No initial data injection needed - artifacts are accessed via async functions
+		return {};
+	}
+
+	getRuntime(): (sandboxId: string) => void {
+		// This function will be stringified, so no external references!
+		return (sandboxId: string) => {
+			// Helper to send message and wait for response
+			const sendArtifactMessage = (action: string, data: any): Promise<any> => {
+				console.log("Sending artifact message:", action, data);
+				return new Promise((resolve, reject) => {
+					const messageId = `artifact_${Date.now()}_${Math.random().toString(36).substring(2, 9)}`;
+
+					const handler = (event: MessageEvent) => {
+						if (event.data.type === "artifact-response" && event.data.messageId === messageId) {
+							window.removeEventListener("message", handler);
+							if (event.data.success) {
+								resolve(event.data.result);
+							} else {
+								reject(new Error(event.data.error || "Artifact operation failed"));
+							}
+						}
+					};
+
+					window.addEventListener("message", handler);
+
+					window.parent.postMessage(
+						{
+							type: "artifact-operation",
+							sandboxId,
+							messageId,
+							action,
+							data,
+						},
+						"*",
+					);
+				});
+			};
+
+			// Auto-parse/stringify for .json files
+			const isJsonFile = (filename: string) => filename.endsWith(".json");
+
+			(window as any).hasArtifact = async (filename: string): Promise<boolean> => {
+				return await sendArtifactMessage("has", { filename });
+			};
+
+			(window as any).getArtifact = async (filename: string): Promise<any> => {
+				const content = await sendArtifactMessage("get", { filename });
+				// Auto-parse .json files
+				if (isJsonFile(filename)) {
+					try {
+						return JSON.parse(content);
+					} catch (e) {
+						throw new Error(`Failed to parse JSON from ${filename}: ${e}`);
+					}
+				}
+				return content;
+			};
+
+			(window as any).createArtifact = async (filename: string, content: any, mimeType?: string): Promise<void> => {
+				let finalContent = content;
+				let finalMimeType = mimeType;
+
+				// Auto-stringify .json files
+				if (isJsonFile(filename) && typeof content !== "string") {
+					finalContent = JSON.stringify(content, null, 2);
+					finalMimeType = mimeType || "application/json";
+				} else if (typeof content === "string") {
+					finalContent = content;
+					finalMimeType = mimeType || "text/plain";
+				} else {
+					finalContent = JSON.stringify(content, null, 2);
+					finalMimeType = mimeType || "application/json";
+				}
+
+				await sendArtifactMessage("create", { filename, content: finalContent, mimeType: finalMimeType });
+			};
+
+			(window as any).updateArtifact = async (filename: string, content: any, mimeType?: string): Promise<void> => {
+				let finalContent = content;
+				let finalMimeType = mimeType;
+
+				// Auto-stringify .json files
+				if (isJsonFile(filename) && typeof content !== "string") {
+					finalContent = JSON.stringify(content, null, 2);
+					finalMimeType = mimeType || "application/json";
+				} else if (typeof content === "string") {
+					finalContent = content;
+					finalMimeType = mimeType || "text/plain";
+				} else {
+					finalContent = JSON.stringify(content, null, 2);
+					finalMimeType = mimeType || "application/json";
+				}
+
+				await sendArtifactMessage("update", { filename, content: finalContent, mimeType: finalMimeType });
+			};
+
+			(window as any).deleteArtifact = async (filename: string): Promise<void> => {
+				await sendArtifactMessage("delete", { filename });
+			};
+		};
+	}
+
+	async handleMessage(message: any, respond: (response: any) => void): Promise<boolean> {
+		if (message.type !== "artifact-operation") {
+			return false;
+		}
+
+		const { action, data, messageId } = message;
+
+		const sendResponse = (success: boolean, result?: any, error?: string) => {
+			respond({
+				type: "artifact-response",
+				messageId,
+				success,
+				result,
+				error,
+			});
+		};
+
+		try {
+			switch (action) {
+				case "has": {
+					const artifacts = this.getArtifactsFn();
+					const exists = artifacts.has(data.filename);
+					sendResponse(true, exists);
+					break;
+				}
+
+				case "get": {
+					const artifacts = this.getArtifactsFn();
+					const artifact = artifacts.get(data.filename);
+					if (!artifact) {
+						sendResponse(false, undefined, `Artifact not found: ${data.filename}`);
+					} else {
+						sendResponse(true, artifact.content);
+					}
+					break;
+				}
+
+				case "create": {
+					try {
+						// Note: mimeType parameter is ignored - artifact type is inferred from filename extension
+						// Third parameter is title, defaults to filename
+						await this.createArtifactFn(data.filename, data.content, data.filename);
+						// Append artifact message for session persistence
+						this.appendMessageFn?.({
+							role: "artifact",
+							action: "create",
+							filename: data.filename,
+							content: data.content,
+							title: data.filename,
+							timestamp: new Date().toISOString(),
+						});
+						sendResponse(true);
+					} catch (err: any) {
+						sendResponse(false, undefined, err.message);
+					}
+					break;
+				}
+
+				case "update": {
+					try {
+						// Note: mimeType parameter is ignored - artifact type is inferred from filename extension
+						// Third parameter is title, defaults to filename
+						await this.updateArtifactFn(data.filename, data.content, data.filename);
+						// Append artifact message for session persistence
+						this.appendMessageFn?.({
+							role: "artifact",
+							action: "update",
+							filename: data.filename,
+							content: data.content,
+							timestamp: new Date().toISOString(),
+						});
+						sendResponse(true);
+					} catch (err: any) {
+						sendResponse(false, undefined, err.message);
+					}
+					break;
+				}
+
+				case "delete": {
+					try {
+						await this.deleteArtifactFn(data.filename);
+						// Append artifact message for session persistence
+						this.appendMessageFn?.({
+							role: "artifact",
+							action: "delete",
+							filename: data.filename,
+							timestamp: new Date().toISOString(),
+						});
+						sendResponse(true);
+					} catch (err: any) {
+						sendResponse(false, undefined, err.message);
+					}
+					break;
+				}
+
+				default:
+					sendResponse(false, undefined, `Unknown artifact action: ${action}`);
+			}
+
+			return true;
+		} catch (error: any) {
+			sendResponse(false, undefined, error.message);
+			return true;
+		}
+	}
+
+	getDescription(): string {
+		return ARTIFACTS_RUNTIME_PROVIDER_DESCRIPTION;
+	}
+}

packages/web-ui/src/components/sandbox/AttachmentsRuntimeProvider.ts

@@ -1,3 +1,4 @@
+import { ATTACHMENTS_RUNTIME_DESCRIPTION } from "../../prompts/tool-prompts.js";
 import type { Attachment } from "../../utils/attachment-utils.js";
 import type { SandboxRuntimeProvider } from "./SandboxRuntimeProvider.js";
 
@@ -96,4 +97,8 @@ export class AttachmentsRuntimeProvider implements SandboxRuntimeProvider {
 			};
 		};
 	}
+
+	getDescription(): string {
+		return ATTACHMENTS_RUNTIME_DESCRIPTION;
+	}
 }

packages/web-ui/src/components/sandbox/SandboxMessageRouter.ts

@@ -8,7 +8,7 @@ export interface MessageConsumer {
 	 * Handle a message from a sandbox.
 	 * @returns true if message was consumed (stops propagation), false otherwise
 	 */
-	handleMessage(message: any): boolean;
+	handleMessage(message: any): Promise<boolean>;
 }
 
 /**
@@ -111,7 +111,7 @@ export class SandboxMessageRouter {
 	private setupListener(): void {
 		if (this.messageListener) return;
 
-		this.messageListener = (e: MessageEvent) => {
+		this.messageListener = async (e: MessageEvent) => {
 			const { sandboxId } = e.data;
 			if (!sandboxId) return;
 
@@ -129,14 +129,14 @@ export class SandboxMessageRouter {
 			// 1. Try provider handlers first (for bidirectional comm like memory)
 			for (const provider of context.providers) {
 				if (provider.handleMessage) {
-					const handled = provider.handleMessage(e.data, respond);
+					const handled = await provider.handleMessage(e.data, respond);
 					if (handled) return; // Stop if handled
 				}
 			}
 
 			// 2. Broadcast to consumers (for one-way messages like console)
 			for (const consumer of context.consumers) {
-				const consumed = consumer.handleMessage(e.data);
+				const consumed = await consumer.handleMessage(e.data);
 				if (consumed) break; // Stop if consumed
 			}
 		};

packages/web-ui/src/components/sandbox/SandboxRuntimeProvider.ts

@@ -26,5 +26,11 @@ export interface SandboxRuntimeProvider {
 	 * @param respond - Function to send a response back to the sandbox
 	 * @returns true if message was handled, false otherwise
 	 */
-	handleMessage?(message: any, respond: (response: any) => void): boolean;
+	handleMessage?(message: any, respond: (response: any) => void): Promise<boolean>;
+
+	/**
+	 * Optional documentation describing what globals/functions this provider injects.
+	 * This will be appended to tool descriptions dynamically so the LLM knows what's available.
+	 */
+	getDescription?(): string;
 }

packages/web-ui/src/index.ts

@@ -42,6 +42,8 @@ export { ModelSelector } from "./dialogs/ModelSelector.js";
 export { PersistentStorageDialog } from "./dialogs/PersistentStorageDialog.js";
 export { SessionListDialog } from "./dialogs/SessionListDialog.js";
 export { ApiKeysTab, ProxyTab, SettingsDialog, SettingsTab } from "./dialogs/SettingsDialog.js";
+// Prompts
+export { ARTIFACTS_RUNTIME_PROVIDER_DESCRIPTION } from "./prompts/tool-prompts.js";
 // Storage
 export { AppStorage, getAppStorage, setAppStorage } from "./storage/app-storage.js";
 export { IndexedDBStorageBackend } from "./storage/backends/indexeddb-storage-backend.js";

packages/web-ui/src/prompts/tool-prompts.ts

@@ -0,0 +1,251 @@
+/**
+ * Centralized tool prompts/descriptions.
+ * Each prompt is either a string constant or a template function.
+ */
+
+// ============================================================================
+// JavaScript REPL Tool
+// ============================================================================
+
+export const JAVASCRIPT_REPL_BASE_DESCRIPTION = `Execute JavaScript code in a sandboxed browser environment with full modern browser capabilities.
+
+Environment: Modern browser with ALL Web APIs available:
+- ES2023+ JavaScript (async/await, optional chaining, nullish coalescing, etc.)
+- DOM APIs (document, window, Canvas, WebGL, etc.)
+- Fetch API for HTTP requests
+
+Loading external libraries via dynamic imports (use esm.run):
+- XLSX (Excel files): const XLSX = await import('https://esm.run/xlsx');
+- Papa Parse (CSV): const Papa = (await import('https://esm.run/papaparse')).default;
+- Lodash: const _ = await import('https://esm.run/lodash-es');
+- D3.js: const d3 = await import('https://esm.run/d3');
+- Chart.js: const Chart = (await import('https://esm.run/chart.js/auto')).default;
+- Three.js: const THREE = await import('https://esm.run/three');
+- Any npm package: await import('https://esm.run/package-name')
+
+IMPORTANT for graphics/canvas:
+- Use fixed dimensions like 400x400 or 800x600, NOT window.innerWidth/Height
+- For Three.js: renderer.setSize(400, 400) and camera aspect ratio of 1
+- For Chart.js: Set options: { responsive: false, animation: false } to ensure immediate rendering
+- Web Storage (localStorage, sessionStorage, IndexedDB)
+- Web Workers, WebAssembly, WebSockets
+- Media APIs (Audio, Video, WebRTC)
+- File APIs (Blob, FileReader, etc.)
+- Crypto API for cryptography
+- And much more - anything a modern browser supports!
+
+Output:
+- console.log() - All output is captured as text`;
+
+export const JAVASCRIPT_REPL_CHART_EXAMPLE = `
+    - Chart.js example:
+      const Chart = (await import('https://esm.run/chart.js/auto')).default;
+      const canvas = document.createElement('canvas');
+      canvas.width = 400; canvas.height = 300;
+      document.body.appendChild(canvas);
+      new Chart(canvas, {
+        type: 'line',
+        data: {
+          labels: ['Jan', 'Feb', 'Mar', 'Apr'],
+          datasets: [{ label: 'Sales', data: [10, 20, 15, 25], borderColor: 'blue' }]
+        },
+        options: { responsive: false, animation: false }
+      });
+      const blob = await new Promise(resolve => canvas.toBlob(resolve, 'image/png'));
+      await returnFile('chart.png', blob, 'image/png');`;
+
+export const JAVASCRIPT_REPL_FOOTER = `
+
+- All standard browser globals (window, document, fetch, etc.)`;
+
+/**
+ * Build complete JavaScript REPL description with optional provider docs.
+ */
+export function buildJavaScriptReplDescription(providerDocs?: string): string {
+	return (
+		JAVASCRIPT_REPL_BASE_DESCRIPTION +
+		(providerDocs ? "\n" + providerDocs + JAVASCRIPT_REPL_CHART_EXAMPLE : "") +
+		JAVASCRIPT_REPL_FOOTER
+	);
+}
+
+// ============================================================================
+// Artifacts Tool
+// ============================================================================
+
+export const ARTIFACTS_BASE_DESCRIPTION = `Creates and manages file artifacts. Each artifact is a file with a filename and content.
+
+IMPORTANT: Always prefer updating existing files over creating new ones. Check available files first.
+
+Commands:
+1. create: Create a new file
+   - filename: Name with extension (required, e.g., 'index.html', 'script.js', 'README.md')
+   - title: Display name for the tab (optional, defaults to filename)
+   - content: File content (required)
+
+2. update: Update part of an existing file
+   - filename: File to update (required)
+   - old_str: Exact string to replace (required)
+   - new_str: Replacement string (required)
+
+3. rewrite: Completely replace a file's content
+   - filename: File to rewrite (required)
+   - content: New content (required)
+   - title: Optionally update display title
+
+4. get: Retrieve the full content of a file
+   - filename: File to retrieve (required)
+   - Returns the complete file content
+
+5. delete: Delete a file
+   - filename: File to delete (required)
+
+6. logs: Get console logs and errors (HTML files only)
+   - filename: HTML file to get logs for (required)
+   - Returns all console output and runtime errors`;
+
+export const ARTIFACTS_RUNTIME_EXAMPLE = `- Example HTML artifact that processes a CSV attachment:
+  <script>
+    // List available files
+    const files = listFiles();
+    console.log('Available files:', files);
+
+    // Find CSV file
+    const csvFile = files.find(f => f.mimeType === 'text/csv');
+    if (csvFile) {
+      const csvContent = readTextFile(csvFile.id);
+      // Process CSV data...
+    }
+
+    // Display image
+    const imageFile = files.find(f => f.mimeType.startsWith('image/'));
+    if (imageFile) {
+      const bytes = readBinaryFile(imageFile.id);
+      const blob = new Blob([bytes], {type: imageFile.mimeType});
+      const url = URL.createObjectURL(blob);
+      document.body.innerHTML = '<img src="' + url + '">';
+    }
+  </script>
+`;
+
+export const ARTIFACTS_HTML_SECTION = `
+For text/html artifacts:
+- Must be a single self-contained file
+- External scripts: Use CDNs like https://esm.sh, https://unpkg.com, or https://cdnjs.cloudflare.com
+- Preferred: Use https://esm.sh for npm packages (e.g., https://esm.sh/three for Three.js)
+- For ES modules, use: <script type="module">import * as THREE from 'https://esm.sh/three';</script>
+- For Three.js specifically: import from 'https://esm.sh/three' or 'https://esm.sh/three@0.160.0'
+- For addons: import from 'https://esm.sh/three/examples/jsm/controls/OrbitControls.js'
+- No localStorage/sessionStorage - use in-memory variables only
+- CSS should be included inline
+- CRITICAL REMINDER FOR HTML ARTIFACTS:
+	- ALWAYS set a background color inline in <style> or directly on body element
+	- Failure to set a background color is a COMPLIANCE ERROR
+	- Background color MUST be explicitly defined to ensure visibility and proper rendering
+- Can embed base64 images directly in img tags
+- Ensure the layout is responsive as the iframe might be resized
+- Note: Network errors (404s) for external scripts may not be captured in logs due to browser security
+
+For application/vnd.ant.code artifacts:
+- Include the language parameter for syntax highlighting
+- Supports all major programming languages
+
+For text/markdown:
+- Standard markdown syntax
+- Will be rendered with full formatting
+- Can include base64 images using markdown syntax
+
+For image/svg+xml:
+- Complete SVG markup
+- Will be rendered inline
+- Can embed raster images as base64 in SVG
+
+CRITICAL REMINDER FOR ALL ARTIFACTS:
+- Prefer to update existing files rather than creating new ones
+- Keep filenames consistent and descriptive
+- Use appropriate file extensions
+- Ensure HTML artifacts have a defined background color`;
+
+/**
+ * Build complete artifacts description with optional provider docs.
+ */
+export function buildArtifactsDescription(providerDocs?: string): string {
+	const runtimeSection = providerDocs
+		? `
+
+For text/html artifacts with runtime capabilities:${providerDocs}
+${ARTIFACTS_RUNTIME_EXAMPLE}
+`
+		: "";
+
+	return ARTIFACTS_BASE_DESCRIPTION + runtimeSection + ARTIFACTS_HTML_SECTION;
+}
+
+// ============================================================================
+// Artifacts Runtime Provider
+// ============================================================================
+
+export const ARTIFACTS_RUNTIME_PROVIDER_DESCRIPTION = `
+Artifact Management (persistent session files you can access/modify programmatically):
+- await hasArtifact(filename) - Check if artifact exists, returns boolean
+  * Example: if (await hasArtifact('data.json')) { ... }
+- await getArtifact(filename) - Read artifact content, returns string or object
+  * Auto-parses .json files to objects, otherwise returns raw string content
+  * Example: const data = await getArtifact('data.json'); // Returns parsed object
+  * Example: const markdown = await getArtifact('notes.md'); // Returns string
+- await createArtifact(filename, content) - Create new persistent artifact
+  * Auto-stringifies objects for .json files
+  * Example: await createArtifact('data.json', {items: []}) // Auto-stringifies
+  * Example: await createArtifact('research-notes.md', '# Research Notes\\n', 'text/markdown')
+- await updateArtifact(filename, content) - Completely replace artifact content
+  * Auto-stringifies objects for .json files
+  * Full content replacement (not diff-based)
+  * Example: const data = await getArtifact('data.json'); data.items.push(newItem); await updateArtifact('data.json', data);
+  * Example: await updateArtifact('research-notes.md', updatedMarkdown, 'text/markdown')
+- await deleteArtifact(filename) - Delete an artifact
+  * Example: await deleteArtifact('old-notes.md')
+
+Powerful pattern for evolving data:
+  const data = await hasArtifact('data.json') ? await getArtifact('data.json') : {items: []};
+  data.items.push(newScrapedItem);
+  await (await hasArtifact('data.json') ? updateArtifact : createArtifact)('data.json', data);
+
+Binary data must be converted to a base64 string before passing to createArtifact or updateArtifact.
+Example:
+  const blob = await new Promise(resolve => canvas.toBlob(resolve, 'image/png'));
+  const arrayBuffer = await blob.arrayBuffer();
+  const base64 = btoa(String.fromCharCode(...new Uint8Array(arrayBuffer)));
+  await createArtifact('image.png', base64);
+`;
+
+// ============================================================================
+// Attachments Runtime Provider
+// ============================================================================
+
+export const ATTACHMENTS_RUNTIME_DESCRIPTION = `
+Global variables:
+- attachments[] - Array of attachment objects from user messages
+  * Properties:
+    - id: string (unique identifier)
+    - fileName: string (e.g., "data.xlsx")
+    - mimeType: string (e.g., "application/vnd.openxmlformats-officedocument.spreadsheetml.sheet")
+    - size: number (bytes)
+  * Helper functions:
+    - listFiles() - Returns array of {id, fileName, mimeType, size} for all attachments
+    - readTextFile(attachmentId) - Returns text content of attachment (for CSV, JSON, text files)
+    - readBinaryFile(attachmentId) - Returns Uint8Array of binary data (for images, Excel, etc.)
+  * Examples:
+    - const files = listFiles();
+    - const csvContent = readTextFile(files[0].id); // Read CSV as text
+    - const xlsxBytes = readBinaryFile(files[0].id); // Read Excel as binary
+- await returnFile(filename, content, mimeType?) - Create downloadable files (async function!)
+  * Always use await with returnFile
+  * REQUIRED: For Blob/Uint8Array binary content, you MUST supply a proper MIME type (e.g., "image/png").
+    If omitted, the REPL throws an Error with stack trace pointing to the offending line.
+  * Strings without a MIME default to text/plain.
+  * Objects are auto-JSON stringified and default to application/json unless a MIME is provided.
+  * Canvas images: Use toBlob() with await Promise wrapper
+  * Examples:
+    - await returnFile('data.txt', 'Hello World', 'text/plain')
+    - await returnFile('data.json', {key: 'value'}, 'application/json')
+    - await returnFile('data.csv', 'name,age\\nJohn,30', 'text/csv')`;

packages/web-ui/src/tools/artifacts/ArtifactElement.ts

@@ -2,7 +2,6 @@ import { LitElement, type TemplateResult } from "lit";
 
 export abstract class ArtifactElement extends LitElement {
 	public filename = "";
-	public displayTitle = "";
 
 	protected override createRenderRoot(): HTMLElement | DocumentFragment {
 		return this; // light DOM for shared styles

packages/web-ui/src/tools/artifacts/HtmlArtifact.ts

@@ -16,7 +16,6 @@ import "./Console.js";
 @customElement("html-artifact")
 export class HtmlArtifact extends ArtifactElement {
 	@property() override filename = "";
-	@property({ attribute: false }) override displayTitle = "";
 	@property({ attribute: false }) runtimeProviders: SandboxRuntimeProvider[] = [];
 	@property({ attribute: false }) sandboxUrlProvider?: () => string;
 
@@ -87,7 +86,7 @@ export class HtmlArtifact extends ArtifactElement {
 
 		// Create consumer for console messages
 		const consumer: MessageConsumer = {
-			handleMessage: (message: any): boolean => {
+			handleMessage: async (message: any): Promise<boolean> => {
 				if (message.type === "console") {
 					// Create new array reference for Lit reactivity
 					this.logs = [

packages/web-ui/src/tools/artifacts/MarkdownArtifact.ts

@@ -10,7 +10,6 @@ import { ArtifactElement } from "./ArtifactElement.js";
 @customElement("markdown-artifact")
 export class MarkdownArtifact extends ArtifactElement {
 	@property() override filename = "";
-	@property({ attribute: false }) override displayTitle = "";
 
 	private _content = "";
 	override get content(): string {

packages/web-ui/src/tools/artifacts/SvgArtifact.ts

@@ -9,7 +9,6 @@ import { ArtifactElement } from "./ArtifactElement.js";
 @customElement("svg-artifact")
 export class SvgArtifact extends ArtifactElement {
 	@property() override filename = "";
-	@property({ attribute: false }) override displayTitle = "";
 
 	private _content = "";
 	override get content(): string {

packages/web-ui/src/tools/artifacts/TextArtifact.ts

@@ -56,7 +56,6 @@ const CODE_EXTENSIONS = [
 @customElement("text-artifact")
 export class TextArtifact extends ArtifactElement {
 	@property() override filename = "";
-	@property({ attribute: false }) override displayTitle = "";
 
 	private _content = "";
 	override get content(): string {

packages/web-ui/src/tools/artifacts/artifacts.ts

@@ -6,7 +6,9 @@ import { html, LitElement, type TemplateResult } from "lit";
 import { customElement, property, state } from "lit/decorators.js";
 import { createRef, type Ref, ref } from "lit/directives/ref.js";
 import { X } from "lucide";
+import type { ArtifactMessage } from "../../components/Messages.js";
 import type { SandboxRuntimeProvider } from "../../components/sandbox/SandboxRuntimeProvider.js";
+import { buildArtifactsDescription } from "../../prompts/tool-prompts.js";
 import { i18n } from "../../utils/i18n.js";
 import type { ArtifactElement } from "./ArtifactElement.js";
 import { HtmlArtifact } from "./HtmlArtifact.js";
@@ -17,7 +19,6 @@ import { TextArtifact } from "./TextArtifact.js";
 // Simple artifact model
 export interface Artifact {
 	filename: string;
-	title: string;
 	content: string;
 	createdAt: Date;
 	updatedAt: Date;
@@ -29,7 +30,6 @@ const artifactsParamsSchema = Type.Object({
 		description: "The operation to perform",
 	}),
 	filename: Type.String({ description: "Filename including extension (e.g., 'index.html', 'script.js')" }),
-	title: Type.Optional(Type.String({ description: "Display title for the tab (defaults to filename)" })),
 	content: Type.Optional(Type.String({ description: "File content" })),
 	old_str: Type.Optional(Type.String({ description: "String to replace (for update command)" })),
 	new_str: Type.Optional(Type.String({ description: "Replacement string (for update command)" })),
@@ -101,7 +101,7 @@ export class ArtifactsPanel extends LitElement {
 	}
 
 	// Get or create artifact element
-	private getOrCreateArtifactElement(filename: string, content: string, title: string): ArtifactElement {
+	private getOrCreateArtifactElement(filename: string, content: string): ArtifactElement {
 		let element = this.artifactElements.get(filename);
 
 		if (!element) {
@@ -121,7 +121,6 @@ export class ArtifactsPanel extends LitElement {
 				element = new TextArtifact();
 			}
 			element.filename = filename;
-			element.displayTitle = title;
 			element.content = content;
 			element.style.display = "none";
 			element.style.height = "100%";
@@ -143,7 +142,6 @@ export class ArtifactsPanel extends LitElement {
 		} else {
 			// Just update content
 			element.content = content;
-			element.displayTitle = title;
 			if (element instanceof HtmlArtifact) {
 				const runtimeProviders = this.runtimeProvidersFactory?.() || [];
 				element.runtimeProviders = runtimeProviders;
@@ -179,106 +177,20 @@ export class ArtifactsPanel extends LitElement {
 
 	// Build the AgentTool (no details payload; return only output strings)
 	public get tool(): AgentTool<typeof artifactsParamsSchema, undefined> {
+		const self = this;
 		return {
 			label: "Artifacts",
 			name: "artifacts",
-			description: `Creates and manages file artifacts. Each artifact is a file with a filename and content.
+			get description() {
+				// Get dynamic provider descriptions
+				const providers = self.runtimeProvidersFactory?.() || [];
+				const providerDocs = providers
+					.map((p) => p.getDescription?.())
+					.filter(Boolean)
+					.join("\n");
 
-IMPORTANT: Always prefer updating existing files over creating new ones. Check available files first.
+				return buildArtifactsDescription(providerDocs || undefined);
-
+			},
-Commands:
-1. create: Create a new file
-   - filename: Name with extension (required, e.g., 'index.html', 'script.js', 'README.md')
-   - title: Display name for the tab (optional, defaults to filename)
-   - content: File content (required)
-
-2. update: Update part of an existing file
-   - filename: File to update (required)
-   - old_str: Exact string to replace (required)
-   - new_str: Replacement string (required)
-
-3. rewrite: Completely replace a file's content
-   - filename: File to rewrite (required)
-   - content: New content (required)
-   - title: Optionally update display title
-
-4. get: Retrieve the full content of a file
-   - filename: File to retrieve (required)
-   - Returns the complete file content
-
-5. delete: Delete a file
-   - filename: File to delete (required)
-
-6. logs: Get console logs and errors (HTML files only)
-   - filename: HTML file to get logs for (required)
-   - Returns all console output and runtime errors
-
-For text/html artifacts with attachments:
-- HTML artifacts automatically have access to user attachments via JavaScript
-- Available global functions in HTML artifacts:
-  * listFiles() - Returns array of {id, fileName, mimeType, size} for all attachments
-  * readTextFile(attachmentId) - Returns text content of attachment (for CSV, JSON, text files)
-  * readBinaryFile(attachmentId) - Returns Uint8Array of binary data (for images, Excel, etc.)
-- Example HTML artifact that processes a CSV attachment:
-  <script>
-    // List available files
-    const files = listFiles();
-    console.log('Available files:', files);
-
-    // Find CSV file
-    const csvFile = files.find(f => f.mimeType === 'text/csv');
-    if (csvFile) {
-      const csvContent = readTextFile(csvFile.id);
-      // Process CSV data...
-    }
-
-    // Display image
-    const imageFile = files.find(f => f.mimeType.startsWith('image/'));
-    if (imageFile) {
-      const bytes = readBinaryFile(imageFile.id);
-      const blob = new Blob([bytes], {type: imageFile.mimeType});
-      const url = URL.createObjectURL(blob);
-      document.body.innerHTML = '<img src="' + url + '">';
-    }
-  </script>
-
-For text/html artifacts:
-- Must be a single self-contained file
-- External scripts: Use CDNs like https://esm.sh, https://unpkg.com, or https://cdnjs.cloudflare.com
-- Preferred: Use https://esm.sh for npm packages (e.g., https://esm.sh/three for Three.js)
-- For ES modules, use: <script type="module">import * as THREE from 'https://esm.sh/three';</script>
-- For Three.js specifically: import from 'https://esm.sh/three' or 'https://esm.sh/three@0.160.0'
-- For addons: import from 'https://esm.sh/three/examples/jsm/controls/OrbitControls.js'
-- No localStorage/sessionStorage - use in-memory variables only
-- CSS should be included inline
-- CRITICAL REMINDER FOR HTML ARTIFACTS:
-	- ALWAYS set a background color inline in <style> or directly on body element
-	- Failure to set a background color is a COMPLIANCE ERROR
-	- Background color MUST be explicitly defined to ensure visibility and proper rendering
-- Can embed base64 images directly in img tags
-- Ensure the layout is responsive as the iframe might be resized
-- Note: Network errors (404s) for external scripts may not be captured in logs due to browser security
-
-For application/vnd.ant.code artifacts:
-- Include the language parameter for syntax highlighting
-- Supports all major programming languages
-
-For text/markdown:
-- Standard markdown syntax
-- Will be rendered with full formatting
-- Can include base64 images using markdown syntax
-
-For image/svg+xml:
-- Complete SVG markup
-- Will be rendered inline
-- Can embed raster images as base64 in SVG
-
-CRITICAL REMINDER FOR ALL ARTIFACTS:
-- Prefer to update existing files rather than creating new ones
-- Keep filenames consistent and descriptive
-- Use appropriate file extensions
-- Ensure HTML artifacts have a defined background color
-`,
 			parameters: artifactsParamsSchema,
 			// Execute mutates our local store and returns a plain output
 			execute: async (_toolCallId: string, args: Static<typeof artifactsParamsSchema>, _signal?: AbortSignal) => {
@@ -289,7 +201,9 @@ CRITICAL REMINDER FOR ALL ARTIFACTS:
 	}
 
 	// Re-apply artifacts by scanning a message list (optional utility)
-	public async reconstructFromMessages(messages: Array<Message | { role: "aborted" }>): Promise<void> {
+	public async reconstructFromMessages(
+		messages: Array<Message | { role: "aborted" } | { role: "artifact" }>,
+	): Promise<void> {
 		const toolCalls = new Map<string, ToolCall>();
 		const artifactToolName = "artifacts";
 
@@ -307,7 +221,34 @@ CRITICAL REMINDER FOR ALL ARTIFACTS:
 		// 2) Build an ordered list of successful artifact operations
 		const operations: Array<ArtifactsParams> = [];
 		for (const m of messages) {
-			if ((m as any).role === "toolResult" && (m as any).toolName === artifactToolName && !(m as any).isError) {
+			// Handle artifact messages (from programmatic operations like browser_javascript)
+			if ((m as any).role === "artifact") {
+				const artifactMsg = m as ArtifactMessage;
+				switch (artifactMsg.action) {
+					case "create":
+						operations.push({
+							command: "create",
+							filename: artifactMsg.filename,
+							content: artifactMsg.content,
+						});
+						break;
+					case "update":
+						operations.push({
+							command: "rewrite",
+							filename: artifactMsg.filename,
+							content: artifactMsg.content,
+						});
+						break;
+					case "delete":
+						operations.push({
+							command: "delete",
+							filename: artifactMsg.filename,
+						});
+						break;
+				}
+			}
+			// Handle tool result messages (from artifacts tool calls)
+			else if ((m as any).role === "toolResult" && (m as any).toolName === artifactToolName && !(m as any).isError) {
 				const toolCallId = (m as any).toolCallId as string;
 				const call = toolCalls.get(toolCallId);
 				if (!call) continue;
@@ -318,30 +259,27 @@ CRITICAL REMINDER FOR ALL ARTIFACTS:
 		}
 
 		// 3) Compute final state per filename by simulating operations in-memory
-		type FinalArtifact = { title: string; content: string };
+		const finalArtifacts = new Map<string, string>();
-		const finalArtifacts = new Map<string, FinalArtifact>();
 		for (const op of operations) {
 			const filename = op.filename;
 			switch (op.command) {
 				case "create": {
 					if (op.content) {
-						finalArtifacts.set(filename, { title: op.title || filename, content: op.content });
+						finalArtifacts.set(filename, op.content);
 					}
 					break;
 				}
 				case "rewrite": {
 					if (op.content) {
-						// If file didn't exist earlier but rewrite succeeded, treat as fresh content
+						finalArtifacts.set(filename, op.content);
-						const existing = finalArtifacts.get(filename);
-						finalArtifacts.set(filename, { title: op.title || existing?.title || filename, content: op.content });
 					}
 					break;
 				}
 				case "update": {
-					const existing = finalArtifacts.get(filename);
+					let existing = finalArtifacts.get(filename);
 					if (!existing) break; // skip invalid update (shouldn't happen for successful results)
 					if (op.old_str !== undefined && op.new_str !== undefined) {
-						existing.content = existing.content.replace(op.old_str, op.new_str);
+						existing = existing.replace(op.old_str, op.new_str);
 						finalArtifacts.set(filename, existing);
 					}
 					break;
@@ -367,8 +305,8 @@ CRITICAL REMINDER FOR ALL ARTIFACTS:
 		this._artifacts = new Map(this._artifacts);
 
 		// 5) Create artifacts in a single pass without waiting for iframe execution or tab switching
-		for (const [filename, { title, content }] of finalArtifacts.entries()) {
+		for (const [filename, content] of finalArtifacts.entries()) {
-			const createParams: ArtifactsParams = { command: "create", filename, title, content } as const;
+			const createParams: ArtifactsParams = { command: "create", filename, content } as const;
 			try {
 				await this.createArtifact(createParams, { skipWait: true, silent: true });
 			} catch {
@@ -436,10 +374,8 @@ CRITICAL REMINDER FOR ALL ARTIFACTS:
 			return `Error: File ${params.filename} already exists`;
 		}
 
-		const title = params.title || params.filename;
 		const artifact: Artifact = {
 			filename: params.filename,
-			title: title,
 			content: params.content,
 			createdAt: new Date(),
 			updatedAt: new Date(),
@@ -448,7 +384,7 @@ CRITICAL REMINDER FOR ALL ARTIFACTS:
 		this._artifacts = new Map(this._artifacts);
 
 		// Create or update element
-		this.getOrCreateArtifactElement(params.filename, params.content, title);
+		this.getOrCreateArtifactElement(params.filename, params.content);
 		if (!options.silent) {
 			this.showArtifact(params.filename);
 			this.onArtifactsChange?.();
@@ -487,7 +423,7 @@ CRITICAL REMINDER FOR ALL ARTIFACTS:
 		this._artifacts.set(params.filename, artifact);
 
 		// Update element
-		this.getOrCreateArtifactElement(params.filename, artifact.content, artifact.title);
+		this.getOrCreateArtifactElement(params.filename, artifact.content);
 		if (!options.silent) {
 			this.onArtifactsChange?.();
 			this.requestUpdate();
@@ -521,12 +457,11 @@ CRITICAL REMINDER FOR ALL ARTIFACTS:
 		}
 
 		artifact.content = params.content;
-		if (params.title) artifact.title = params.title;
 		artifact.updatedAt = new Date();
 		this._artifacts.set(params.filename, artifact);
 
 		// Update element
-		this.getOrCreateArtifactElement(params.filename, artifact.content, artifact.title);
+		this.getOrCreateArtifactElement(params.filename, artifact.content);
 		if (!options.silent) {
 			this.onArtifactsChange?.();
 		}

packages/web-ui/src/tools/javascript-repl.ts

@@ -5,6 +5,7 @@ import { createRef, ref } from "lit/directives/ref.js";
 import { Code } from "lucide";
 import { type SandboxFile, SandboxIframe, type SandboxResult } from "../components/SandboxedIframe.js";
 import type { SandboxRuntimeProvider } from "../components/sandbox/SandboxRuntimeProvider.js";
+import { buildJavaScriptReplDescription } from "../prompts/tool-prompts.js";
 import type { Attachment } from "../utils/attachment-utils.js";
 import { registerToolRenderer, renderCollapsibleHeader, renderHeader } from "./renderer-registry.js";
 import type { ToolRenderer } from "./types.js";
@@ -125,78 +126,16 @@ export function createJavaScriptReplTool(): AgentTool<typeof javascriptReplSchem
 		name: "javascript_repl",
 		runtimeProvidersFactory: () => [], // default to empty array
 		sandboxUrlProvider: undefined, // optional, for browser extensions
-		description: `Execute JavaScript code in a sandboxed browser environment with full modern browser capabilities.
+		get description() {
+			// Get dynamic provider descriptions
+			const providers = this.runtimeProvidersFactory?.() || [];
+			const providerDocs = providers
+				.map((p) => p.getDescription?.())
+				.filter(Boolean)
+				.join("\n");
 
-Environment: Modern browser with ALL Web APIs available:
+			return buildJavaScriptReplDescription(providerDocs || undefined);
-- ES2023+ JavaScript (async/await, optional chaining, nullish coalescing, etc.)
-- DOM APIs (document, window, Canvas, WebGL, etc.)
-- Fetch API for HTTP requests
-
-Loading external libraries via dynamic imports (use esm.run):
-- XLSX (Excel files): const XLSX = await import('https://esm.run/xlsx');
-- Papa Parse (CSV): const Papa = (await import('https://esm.run/papaparse')).default;
-- Lodash: const _ = await import('https://esm.run/lodash-es');
-- D3.js: const d3 = await import('https://esm.run/d3');
-- Chart.js: const Chart = (await import('https://esm.run/chart.js/auto')).default;
-- Three.js: const THREE = await import('https://esm.run/three');
-- Any npm package: await import('https://esm.run/package-name')
-
-IMPORTANT for graphics/canvas:
-- Use fixed dimensions like 400x400 or 800x600, NOT window.innerWidth/Height
-- For Three.js: renderer.setSize(400, 400) and camera aspect ratio of 1
-- For Chart.js: Set options: { responsive: false, animation: false } to ensure immediate rendering
-- Web Storage (localStorage, sessionStorage, IndexedDB)
-- Web Workers, WebAssembly, WebSockets
-- Media APIs (Audio, Video, WebRTC)
-- File APIs (Blob, FileReader, etc.)
-- Crypto API for cryptography
-- And much more - anything a modern browser supports!
-
-Output:
-- console.log() - All output is captured as text
-- await returnFile(filename, content, mimeType?) - Create downloadable files (async function!)
-  * Always use await with returnFile
-  * REQUIRED: For Blob/Uint8Array binary content, you MUST supply a proper MIME type (e.g., "image/png").
-    If omitted, the REPL throws an Error with stack trace pointing to the offending line.
-  * Strings without a MIME default to text/plain.
-  * Objects are auto-JSON stringified and default to application/json unless a MIME is provided.
-  * Canvas images: Use toBlob() with await Promise wrapper
-  * Examples:
-    - await returnFile('data.txt', 'Hello World', 'text/plain')
-    - await returnFile('data.json', {key: 'value'}, 'application/json')
-    - await returnFile('data.csv', 'name,age\\nJohn,30', 'text/csv')
-    - Chart.js example:
-      const Chart = (await import('https://esm.run/chart.js/auto')).default;
-      const canvas = document.createElement('canvas');
-      canvas.width = 400; canvas.height = 300;
-      document.body.appendChild(canvas);
-      new Chart(canvas, {
-        type: 'line',
-        data: {
-          labels: ['Jan', 'Feb', 'Mar', 'Apr'],
-          datasets: [{ label: 'Sales', data: [10, 20, 15, 25], borderColor: 'blue' }]
 		},
-        options: { responsive: false, animation: false }
-      });
-      const blob = await new Promise(resolve => canvas.toBlob(resolve, 'image/png'));
-      await returnFile('chart.png', blob, 'image/png');
-
-Global variables:
-- attachments[] - Array of attachment objects from user messages
-  * Properties:
-    - id: string (unique identifier)
-    - fileName: string (e.g., "data.xlsx")
-    - mimeType: string (e.g., "application/vnd.openxmlformats-officedocument.spreadsheetml.sheet")
-    - size: number (bytes)
-  * Helper functions:
-    - listFiles() - Returns array of {id, fileName, mimeType, size} for all attachments
-    - readTextFile(attachmentId) - Returns text content of attachment (for CSV, JSON, text files)
-    - readBinaryFile(attachmentId) - Returns Uint8Array of binary data (for images, Excel, etc.)
-  * Examples:
-    - const files = listFiles();
-    - const csvContent = readTextFile(files[0].id); // Read CSV as text
-    - const xlsxBytes = readBinaryFile(files[0].id); // Read Excel as binary
-- All standard browser globals (window, document, fetch, etc.)`,
 		parameters: javascriptReplSchema,
 		execute: async function (_toolCallId: string, args: Static<typeof javascriptReplSchema>, signal?: AbortSignal) {
 			const result = await executeJavaScript(