diff --git a/.claude/launch.json b/.claude/launch.json
new file mode 100644
index 0000000000..f39dfd1f15
--- /dev/null
+++ b/.claude/launch.json
@@ -0,0 +1,29 @@
+{
+  "version": "0.0.1",
+  "configurations": [
+    {
+      "name": "frontend",
+      "runtimeExecutable": "npm",
+      "runtimeArgs": ["run", "dev", "--", "--port", "3100"],
+      "port": 3100,
+      "cwd": "frontend",
+      "env": {
+        "REMOTE": "https://app.windmill.dev"
+      }
+    },
+    {
+      "name": "backend",
+      "runtimeExecutable": "cargo",
+      "runtimeArgs": ["run"],
+      "port": 8000,
+      "cwd": "backend"
+    },
+    {
+      "name": "multiplayer",
+      "runtimeExecutable": "npm",
+      "runtimeArgs": ["run", "dev"],
+      "port": 3002,
+      "cwd": "multiplayer"
+    }
+  ]
+}
diff --git a/frontend/src/lib/components/copilot/chat/AIChatDisplay.svelte b/frontend/src/lib/components/copilot/chat/AIChatDisplay.svelte
index 140f20f140..c7999fc489 100644
--- a/frontend/src/lib/components/copilot/chat/AIChatDisplay.svelte
+++ b/frontend/src/lib/components/copilot/chat/AIChatDisplay.svelte
@@ -2,6 +2,7 @@
 	import AIChatMessage from './AIChatMessage.svelte'
 	import { type Snippet } from 'svelte'
 	import {
+		ArrowUp,
 		CheckIcon,
 		Code2,
 		FileCode,
@@ -122,58 +123,54 @@
 		<div class="flex flex-row items-center gap-2">
 			<Popover>
 				{#snippet trigger()}
-							
-						<Button
-							on:click={() => {}}
-							title="History"
-							size="md"
-							btnClasses="!p-1"
-							startIcon={{ icon: HistoryIcon }}
-							iconOnly
-							variant="border"
-							color="light"
-							propagateEvent
-						/>
-					
-							{/snippet}
+					<Button
+						on:click={() => {}}
+						title="History"
+						size="md"
+						btnClasses="!p-1"
+						startIcon={{ icon: HistoryIcon }}
+						iconOnly
+						variant="border"
+						color="light"
+						propagateEvent
+					/>
+				{/snippet}
 				{#snippet content({ close })}
-							
-						<div class="p-1 overflow-y-auto max-h-[300px]">
-							{#if pastChats.length === 0}
-								<div class="text-center text-primary text-xs">No history</div>
-							{:else}
-								<div class="flex flex-col">
-									{#each pastChats as chat}
-										<button
-											class="text-left flex flex-row items-center gap-2 justify-between hover:bg-gray-100 dark:hover:bg-gray-700 rounded-md p-1"
-											onclick={() => {
-												loadPastChat(chat.id)
-												close()
-											}}
+					<div class="p-1 overflow-y-auto max-h-[300px]">
+						{#if pastChats.length === 0}
+							<div class="text-center text-primary text-xs">No history</div>
+						{:else}
+							<div class="flex flex-col">
+								{#each pastChats as chat}
+									<button
+										class="text-left flex flex-row items-center gap-2 justify-between hover:bg-gray-100 dark:hover:bg-gray-700 rounded-md p-1"
+										onclick={() => {
+											loadPastChat(chat.id)
+											close()
+										}}
+									>
+										<div
+											class="text-xs font-medium w-48 text-ellipsis overflow-hidden whitespace-nowrap flex-1"
+											title={chat.title}
 										>
-											<div
-												class="text-xs font-medium w-48 text-ellipsis overflow-hidden whitespace-nowrap flex-1"
-												title={chat.title}
-											>
-												{chat.title}
-											</div>
-											<Button
-												iconOnly
-												size="xs2"
-												btnClasses="!p-1"
-												variant="default"
-												startIcon={{ icon: X }}
-												on:click={() => {
-													deletePastChat(chat.id)
-												}}
-											/>
-										</button>
-									{/each}
-								</div>
-							{/if}
-						</div>
-					
-							{/snippet}
+											{chat.title}
+										</div>
+										<Button
+											iconOnly
+											size="xs2"
+											btnClasses="!p-1"
+											variant="default"
+											startIcon={{ icon: X }}
+											on:click={() => {
+												deletePastChat(chat.id)
+											}}
+										/>
+									</button>
+								{/each}
+							</div>
+						{/if}
+					</div>
+				{/snippet}
 			</Popover>
 			<Button
 				title="New chat"
@@ -224,7 +221,7 @@
 		</div>
 	{/if}
 
-	<div class:border-t={messages.length > 0} class="relative">
+	<div class="relative px-2 pb-2 pt-1 w-full max-w-xl mx-auto">
 		{#if aiChatManager.loading}
 			<div class="absolute -top-10 w-full flex flex-row justify-center">
 				<Button
@@ -265,28 +262,28 @@
 				</Button>
 			</div>
 		{/if}
-		<div class="px-2">
-			<AIChatInput
-				bind:this={aiChatInput}
-				bind:selectedContext
-				{availableContext}
-				{disabled}
-				isFirstMessage={messages.length === 0}
-			/>
-			<div
-				class={`flex flex-row ${
-					aiChatManager.mode === 'script' && hasDiff ? 'justify-between' : 'justify-end'
-				} items-center`}
-			>
-				{#if aiChatManager.mode === 'script' && hasDiff}
-					<ChatQuickActions {askAi} {diffMode} />
-				{/if}
-				{#if disabled}
-					<div class="text-primary text-xs my-2 px-2">
-						<Markdown md={disabledMessage} />
-					</div>
-				{:else}
-					<div class="flex flex-row gap-x-1.5 min-w-0 flex-wrap items-center">
+		<div
+			class="rounded-2xl border border-light bg-surface shadow-sm transition-all focus-within:shadow-md focus-within:border-gray-300 dark:focus-within:border-gray-600"
+		>
+			<div class="px-1 pt-0.5">
+				<AIChatInput
+					bind:this={aiChatInput}
+					bind:selectedContext
+					{availableContext}
+					{disabled}
+					isFirstMessage={messages.length === 0}
+				/>
+			</div>
+			<div class="flex flex-row items-center justify-between gap-2 px-2 pb-1.5 pt-0.5">
+				<div class="flex flex-row items-center gap-x-1.5 min-w-0 flex-wrap">
+					{#if aiChatManager.mode === 'script' && hasDiff}
+						<ChatQuickActions {askAi} {diffMode} />
+					{/if}
+					{#if disabled}
+						<div class="text-primary text-xs px-1">
+							<Markdown md={disabledMessage} />
+						</div>
+					{:else}
 						<ChatMode />
 						{#if aiChatManager.mode === AIMode.APP}
 							<DatatableCreationPolicy />
@@ -367,12 +364,35 @@
 								</div>
 							{/if}
 						{/if}
-					</div>
+					{/if}
+				</div>
+
+				{#if !disabled}
+					<button
+						type="button"
+						aria-label={aiChatManager.loading ? 'Stop' : 'Send'}
+						title={aiChatManager.loading ? 'Stop' : 'Send'}
+						class="shrink-0 inline-flex items-center justify-center w-7 h-7 rounded-full bg-gray-900 dark:bg-gray-100 text-white dark:text-gray-900 hover:bg-gray-700 dark:hover:bg-gray-300 disabled:opacity-30 disabled:cursor-not-allowed transition-colors"
+						disabled={!aiChatManager.loading && !aiChatInput?.hasContent()}
+						onclick={() => {
+							if (aiChatManager.loading) {
+								cancel()
+							} else {
+								aiChatInput?.triggerSend()
+							}
+						}}
+					>
+						{#if aiChatManager.loading}
+							<Square class="w-3 h-3" />
+						{:else}
+							<ArrowUp class="w-3.5 h-3.5" strokeWidth={2.5} />
+						{/if}
+					</button>
 				{/if}
 			</div>
 		</div>
 		{#if (aiChatManager.mode === AIMode.NAVIGATOR || aiChatManager.mode === AIMode.ASK) && suggestions.length > 0 && messages.filter((m) => m.role === 'user').length === 0 && !disabled}
-			<div class="px-2 mt-4">
+			<div class="mt-4">
 				<div class="flex flex-col gap-2">
 					{#each suggestions as suggestion}
 						<Button
diff --git a/frontend/src/lib/components/copilot/chat/AIChatInput.svelte b/frontend/src/lib/components/copilot/chat/AIChatInput.svelte
index b496dbb6c8..b7632335b3 100644
--- a/frontend/src/lib/components/copilot/chat/AIChatInput.svelte
+++ b/frontend/src/lib/components/copilot/chat/AIChatInput.svelte
@@ -159,6 +159,17 @@
 		}
 	}
 
+	export function triggerSend() {
+		if (disabled) {
+			return
+		}
+		onSendRequest ? onSendRequest(instructions) : sendRequest()
+	}
+
+	export function hasContent(): boolean {
+		return instructions.trim().length > 0
+	}
+
 	$effect(() => {
 		if (editingMessageIndex !== null) {
 			focusInput()
@@ -364,29 +375,25 @@
 			<div class="flex flex-row gap-1 mb-1 overflow-scroll pt-2 no-scrollbar">
 				<Popover>
 					{#snippet trigger()}
-									
-							<div
-								class="border rounded-md px-1 py-0.5 font-normal text-primary text-xs hover:bg-surface-hover bg-surface"
-								>@</div
-							>
-						
-									{/snippet}
+						<div
+							class="border rounded-md px-1 py-0.5 font-normal text-primary text-xs hover:bg-surface-hover bg-surface"
+							>@</div
+						>
+					{/snippet}
 					{#snippet content({ close })}
-									
-							<AvailableContextList
-								{availableContext}
-								{selectedContext}
-								onSelect={(element) => {
-									addContextToSelection(element)
-									close()
-								}}
-								onSelectWorkspaceItem={(element) => {
-									addContextToSelection(element)
-									close()
-								}}
-							/>
-						
-									{/snippet}
+						<AvailableContextList
+							{availableContext}
+							{selectedContext}
+							onSelect={(element) => {
+								addContextToSelection(element)
+								close()
+							}}
+							onSelectWorkspaceItem={(element) => {
+								addContextToSelection(element)
+								close()
+							}}
+						/>
+					{/snippet}
 				</Popover>
 				{#each selectedContext as element}
 					<ContextElementBadge
@@ -423,25 +430,21 @@
 			<div class="flex flex-row gap-1 mb-1 overflow-scroll pt-2 no-scrollbar">
 				<Popover>
 					{#snippet trigger()}
-											
-							<div
-								class="border rounded-md px-1 py-0.5 font-normal text-primary text-xs hover:bg-surface-hover bg-surface"
-								>@</div
-							>
-						
-											{/snippet}
+						<div
+							class="border rounded-md px-1 py-0.5 font-normal text-primary text-xs hover:bg-surface-hover bg-surface"
+							>@</div
+						>
+					{/snippet}
 					{#snippet content({ close })}
-											
-							<AppAvailableContextList
-								{availableContext}
-								{selectedContext}
-								onSelect={(element) => {
-									addContextToSelection(element)
-									close()
-								}}
-							/>
-						
-											{/snippet}
+						<AppAvailableContextList
+							{availableContext}
+							{selectedContext}
+							onSelect={(element) => {
+								addContextToSelection(element)
+								close()
+							}}
+						/>
+					{/snippet}
 				</Popover>
 				{#each selectedContext as element (element.type + '-' + element.title)}
 					<ContextElementBadge
diff --git a/frontend/src/routes/(root)/(logged)/design-sandbox/+page.svelte b/frontend/src/routes/(root)/(logged)/design-sandbox/+page.svelte
new file mode 100644
index 0000000000..32ed8fd22e
--- /dev/null
+++ b/frontend/src/routes/(root)/(logged)/design-sandbox/+page.svelte
@@ -0,0 +1,194 @@
+<script lang="ts">
+	import { onMount } from 'svelte'
+	import { Pane, Splitpanes } from 'svelte-splitpanes'
+	import AIChat from '$lib/components/copilot/chat/AIChat.svelte'
+	import FlowWrapper from '$lib/components/FlowWrapper.svelte'
+	import { chatState } from '$lib/components/copilot/chat/sharedChatState.svelte'
+	import { aiChatManager, AIMode } from '$lib/components/copilot/chat/AIChatManager.svelte'
+	import { copilotInfo } from '$lib/aiStore'
+	import type { DisplayMessage } from '$lib/components/copilot/chat/shared'
+	import type { FlowBuilderWhitelabelCustomUi } from '$lib/components/custom_ui'
+
+	// Fake conversation: user asks the assistant to build a 3-step user-engagement flow.
+	const fakeMessages: DisplayMessage[] = [
+		{
+			role: 'user',
+			index: 0,
+			content:
+				'I need a flow that pulls users from our API every morning, filters out the inactive ones, and sends a re-engagement email to the rest.'
+		},
+		{
+			role: 'assistant',
+			content:
+				"Sounds good — I'll wire that up as three steps: a fetch from your `/users` endpoint, a filter on `last_active_at`, and a notify step that sends the email. Let me add them now."
+		},
+		{
+			role: 'tool',
+			tool_call_id: 'tool_step_a',
+			toolName: 'create_step',
+			content: 'Created step `a` — Fetch users',
+			parameters: { id: 'a', summary: 'Fetch users', language: 'bun' },
+			result: { ok: true, id: 'a' },
+			showDetails: false
+		},
+		{
+			role: 'tool',
+			tool_call_id: 'tool_step_b',
+			toolName: 'create_step',
+			content: 'Created step `b` — Filter active',
+			parameters: { id: 'b', summary: 'Filter active', language: 'python3' },
+			result: { ok: true, id: 'b' },
+			showDetails: false
+		},
+		{
+			role: 'tool',
+			tool_call_id: 'tool_step_c',
+			toolName: 'create_step',
+			content: 'Created step `c` — Notify',
+			parameters: { id: 'c', summary: 'Notify', language: 'bun' },
+			result: { ok: true, id: 'c' },
+			showDetails: false
+		},
+		{
+			role: 'assistant',
+			content:
+				'All three steps are in place:\n\n- **Fetch users** calls `GET /users` and returns the list.\n- **Filter active** keeps users whose `last_active_at` is within the last 30 days.\n- **Notify** sends the `re_engagement_v2` email template to each one.\n\nYou can hit **Test flow** in the top-right to dry-run it. Want me to add a daily schedule trigger as well?'
+		},
+		{
+			role: 'user',
+			index: 1,
+			content:
+				'Yes please, every weekday at 9am Europe/Paris. Also can the email use `name` instead of `first_name`?'
+		},
+		{
+			role: 'assistant',
+			content: "On it — adding the schedule and updating the Notify step's template variable."
+		},
+		{
+			role: 'tool',
+			tool_call_id: 'tool_schedule',
+			toolName: 'add_schedule',
+			content: 'Added weekday schedule at 09:00 Europe/Paris',
+			parameters: { cron: '0 9 * * 1-5', timezone: 'Europe/Paris' },
+			result: { ok: true, schedule_id: 'sched_001' },
+			showDetails: false
+		},
+		{
+			role: 'tool',
+			tool_call_id: 'tool_edit_c',
+			toolName: 'edit_step',
+			content: 'Updated `Notify` to reference `user.name`',
+			parameters: { id: 'c', diff: '- {{ user.first_name }}\n+ {{ user.name }}' },
+			result: { ok: true },
+			showDetails: false,
+			isLoading: true
+		}
+	]
+
+	function applyMocks() {
+		// Pretend Windmill AI is enabled with an Anthropic model so the chat input is active.
+		copilotInfo.set({
+			enabled: true,
+			defaultModel: { model: 'claude-sonnet-4-5', provider: 'anthropic' },
+			aiModels: [{ model: 'claude-sonnet-4-5', provider: 'anthropic' }],
+			customPrompts: {},
+			maxTokensPerModel: {}
+		})
+		aiChatManager.mode = AIMode.FLOW
+		aiChatManager.displayMessages = fakeMessages
+	}
+
+	// The parent (logged) layout always renders its AiChatLayout (right-side chat).
+	// We hide it here and render our own AIChat on the left of the page.
+	onMount(() => {
+		chatState.size = 0
+		applyMocks()
+		// loadCopilot() in the parent layout is async and may overwrite our mock once
+		// it resolves — re-apply after a beat to be safe for design preview.
+		setTimeout(applyMocks, 1500)
+	})
+
+	// Minimal fake flow with a few modules so the editor has something to show.
+	let flowStore = $state({
+		val: {
+			summary: 'Sandbox flow',
+			description: 'A fake flow used to prototype design changes.',
+			value: {
+				modules: [
+					{
+						id: 'a',
+						summary: 'Fetch users',
+						value: {
+							type: 'rawscript' as const,
+							language: 'bun' as const,
+							content:
+								"export async function main() {\n  return [{ id: 1, name: 'Ada' }, { id: 2, name: 'Linus' }]\n}\n",
+							input_transforms: {}
+						}
+					},
+					{
+						id: 'b',
+						summary: 'Filter active',
+						value: {
+							type: 'rawscript' as const,
+							language: 'python3' as const,
+							content: 'def main(users: list):\n    return [u for u in users if u]\n',
+							input_transforms: {
+								users: { type: 'javascript' as const, expr: 'results.a' }
+							}
+						}
+					},
+					{
+						id: 'c',
+						summary: 'Notify',
+						value: {
+							type: 'rawscript' as const,
+							language: 'bun' as const,
+							content:
+								"export async function main(users: any[]) {\n  console.log('notifying', users.length)\n}\n",
+							input_transforms: {
+								users: { type: 'javascript' as const, expr: 'results.b' }
+							}
+						}
+					}
+				]
+			},
+			path: 'u/admin/sandbox_flow',
+			edited_at: '',
+			edited_by: '',
+			archived: false,
+			extra_perms: {},
+			schema: {
+				$schema: 'https://json-schema.org/draft/2020-12/schema',
+				properties: {},
+				required: [],
+				type: 'object'
+			}
+		}
+	})
+
+	let flowStateStore = $state({ val: {} })
+
+	let customUi: FlowBuilderWhitelabelCustomUi = {
+		aiAgent: true
+	}
+</script>
+
+<div class="h-full w-full flex flex-col min-h-0">
+	<Splitpanes horizontal={false} class="flex-1 min-h-0">
+		<Pane size={50} minSize={20} class="flex flex-col min-h-0 border-r border-light">
+			<AIChat />
+		</Pane>
+		<Pane size={50} minSize={30} class="flex flex-col min-h-0">
+			<FlowWrapper
+				disableAi
+				pathStoreInit="u/admin/sandbox_flow"
+				{customUi}
+				selectedId={undefined}
+				newFlow
+				{flowStore}
+				{flowStateStore}
+			/>
+		</Pane>
+	</Splitpanes>
+</div>