From d8aaa73573c46a8a23f6c6850d38438ad395752c Mon Sep 17 00:00:00 2001
From: hugocasa <hugo@casademont.ch>
Date: Tue, 22 Sep 2026 19:07:43 +0200
Subject: [PATCH] feat: chat with a saved agent from the agent editor (#11292)

* feat: chat with a saved agent from the agent editor

* fix: keep agent chats apart from a same-path flow's conversations

* fix: point an agent editor chat's model gap at the agent, not a step

* fix: match the memory gate's icon to the chat's empty state
---
 .../flows/content/AgentEditorHost.svelte      | 202 +++++++++++++++---
 .../flows/content/AgentEditorModal.svelte     |  37 +++-
 .../flows/conversations/FlowChat.svelte       |  13 +-
 .../conversations/FlowChatInterface.svelte    |  11 +-
 .../flows/conversations/agentChatInputs.ts    |  12 +-
 .../conversations/agentEditorChat.test.ts     |  76 +++++++
 .../flows/conversations/agentEditorChat.ts    | 101 +++++++++
 7 files changed, 406 insertions(+), 46 deletions(-)
 create mode 100644 frontend/src/lib/components/flows/conversations/agentEditorChat.test.ts
 create mode 100644 frontend/src/lib/components/flows/conversations/agentEditorChat.ts

diff --git a/frontend/src/lib/components/flows/content/AgentEditorHost.svelte b/frontend/src/lib/components/flows/content/AgentEditorHost.svelte
index b6a98160be..4f69d3a1a1 100644
--- a/frontend/src/lib/components/flows/content/AgentEditorHost.svelte
+++ b/frontend/src/lib/components/flows/content/AgentEditorHost.svelte
@@ -1,7 +1,16 @@
 <script lang="ts">
 	import { getContext, setContext, untrack } from 'svelte'
 	import { writable } from 'svelte/store'
-	import { Alert } from '$lib/components/common'
+	import { Info, MessageCircleOff } from 'lucide-svelte'
+	import { Alert, Button } from '$lib/components/common'
+	import FlowChat from '../conversations/FlowChat.svelte'
+	import {
+		AGENT_CHAT_SCHEMA,
+		agentChatFlow,
+		agentChatGap,
+		agentChatPath
+	} from '../conversations/agentEditorChat'
+	import { runFlowPreview } from '../utils.svelte'
 	import { deepEqual } from 'fast-equals'
 	import type { Flow, FlowModule, InputTransform, Job, OpenFlow } from '$lib/gen'
 	import { emptySchema, type StateStore } from '$lib/utils'
@@ -30,7 +39,12 @@
 		type AIAgentConfig
 	} from '../agentResourceUtils'
 	import { agentArgsToTransforms } from '../linkedAgentDrafts'
-	import { AGENT_EDITOR_RUN_INPUTS, AGENT_TOOLS_ROW } from '../agentFormFields'
+	import {
+		AGENT_EDITOR_RUN_INPUTS,
+		AGENT_TOOLS_ROW,
+		DEFAULT_AGENT_MEMORY,
+		keepsManagedMemory
+	} from '../agentFormFields'
 	import { toolDisplayName, type AgentTool } from '../agentToolUtils'
 	import { useAgentDraft } from '../agentDraft.svelte'
 	import Path from '$lib/components/Path.svelte'
@@ -199,6 +213,17 @@
 	// apart from the echo of their own write.
 	let lastArgs = $state<string | undefined>(undefined)
 
+	// Picked on the first load, after which it is the reader's: following the memory setting live
+	// would pull them out of a chat for switching memory off in the form.
+	let testMode = $state<'form' | 'chat' | undefined>(undefined)
+	// Mounted the first time it is shown, then only hidden: unmounting destroys the SDK chat,
+	// which stops following the turn in flight, and its answer would never show.
+	let chatMounted = $state(false)
+	function showTestMode(mode: 'form' | 'chat') {
+		testMode = mode
+		if (mode === 'chat') chatMounted = true
+	}
+
 	// draft.args -> module. Only when the draft moved on its own (a load, an external write, a
 	// discard); an edit made in the form arrives here as its own echo and is skipped.
 	$effect(() => {
@@ -217,6 +242,7 @@
 				} as any
 			}
 			flowStore.val.value.modules = [built]
+			if (testMode === undefined) showTestMode(keepsManagedMemory(args.memory) ? 'chat' : 'form')
 			// Caught rather than left to float: a tool whose shape the schema loader cannot read
 			// would otherwise reject into the global unhandled-rejection handler, which reports the
 			// bare message and no stack — saying nothing about which agent or tool caused it. The
@@ -294,6 +320,43 @@
 	let testIsLoading = $state(false)
 	let scriptProgress = $state(undefined)
 
+	let chatPath = $derived(agentChatPath(path))
+
+	/** One chat turn: the agent as edited, not as deployed, the same as a run from the form. */
+	async function runChatTurn(
+		userMessage: string,
+		conversationId: string,
+		inputs?: Record<string, any>
+	): Promise<string | undefined> {
+		if (!agentModule) return undefined
+		return await runFlowPreview(
+			{ ...(inputs ?? {}), user_message: userMessage },
+			agentChatFlow($state.snapshot(agentModule) as FlowModule),
+			chatPath,
+			undefined,
+			conversationId,
+			undefined,
+			workspace
+		)
+	}
+
+	// What the composer reads for its model button and paperclip.
+	let chatModules = $derived(agentModule ? agentChatFlow(agentModule).value.modules : undefined)
+	let chatGap = $derived(agentChatGap(agentValue?.input_transforms))
+
+	function turnOnMemory() {
+		if (!agentValue) return
+		agentValue.input_transforms.memory = {
+			type: 'static',
+			value: structuredClone(DEFAULT_AGENT_MEMORY)
+		}
+	}
+
+	function turnOnStreaming() {
+		if (!agentValue) return
+		agentValue.input_transforms.streaming = { type: 'static', value: true }
+	}
+
 	// Adding a tool goes straight into it: the editor has no graph to show the new node on, so the
 	// tool it just created is the only place the click can land.
 	async function addTool(detail: { kind: string; script?: any; flow?: any; inlineScript?: any }) {
@@ -341,6 +404,18 @@
 	export function draftHandle() {
 		return draft
 	}
+	/** The switch between the form and the chat, which the dialog's header holds. `mode` is
+	 *  undefined until the agent loads and picks the first one. */
+	export function testPaneHandle() {
+		return {
+			get mode() {
+				return testMode
+			},
+			set mode(mode: 'form' | 'chat' | undefined) {
+				if (mode) showTestMode(mode)
+			}
+		}
+	}
 </script>
 
 {#if draft.refusal}
@@ -359,7 +434,7 @@
 		<!-- Resizable as the step panel's config and test are: a long system prompt and a long
 		     answer want opposite splits, and only the reader knows which they are on. -->
 		<Splitpanes class="h-full">
-			<Pane size={66} minSize={30}>
+			<Pane size={55} minSize={30}>
 				<div class="h-full min-h-0 overflow-auto">
 					<div class="px-4 pt-4">
 						<Label label="Path">
@@ -410,37 +485,98 @@
 					</PropPickerWrapper>
 				</div>
 			</Pane>
-			<!-- Laid out as the script editor's preview column is: what a run takes above what it
-			     produced, both alongside what is being edited. -->
-			<Pane size={34} minSize={20}>
-				<Splitpanes horizontal class="h-full">
-					<Pane size={40} minSize={15}>
-						<div class="h-full overflow-auto">
-							<ModulePreview
-								mod={agentModule as FlowModule}
-								schema={flowLocalAgentSchema(schema)}
-								pickableProperties={stepPropPicker?.pickableProperties}
-								runInputKeys={AGENT_EDITOR_RUN_INPUTS}
-								bind:testJob
-								bind:testIsLoading
-								bind:scriptProgress
-							/>
+			<Pane size={45} minSize={20}>
+				<div class="h-full min-h-0 flex flex-col">
+					<!-- Laid out as the script editor's preview column is: what a run takes above what it
+					     produced, both alongside what is being edited. -->
+					<div class="flex-1 min-h-0 {testMode === 'chat' ? 'hidden' : ''}">
+						<Splitpanes horizontal class="h-full">
+							<Pane size={40} minSize={15}>
+								<div class="h-full overflow-auto">
+									<ModulePreview
+										mod={agentModule as FlowModule}
+										schema={flowLocalAgentSchema(schema)}
+										pickableProperties={stepPropPicker?.pickableProperties}
+										runInputKeys={AGENT_EDITOR_RUN_INPUTS}
+										bind:testJob
+										bind:testIsLoading
+										bind:scriptProgress
+									/>
+								</div>
+							</Pane>
+							<Pane size={60} minSize={20}>
+								<ModulePreviewResultViewer
+									lang="deno"
+									editor={undefined}
+									diffEditor={undefined}
+									mod={agentModule as FlowModule}
+									{testJob}
+									{testIsLoading}
+									{scriptProgress}
+									disableMock
+									disableHistory
+								/>
+							</Pane>
+						</Splitpanes>
+					</div>
+					{#if chatMounted}
+						<div class={testMode === 'chat' ? 'flex flex-col flex-1 min-h-0' : 'hidden'}>
+							{#if chatGap?.memory}
+								<div
+									class="flex-1 flex flex-col items-center justify-center gap-2 px-8 text-center"
+								>
+									<MessageCircleOff size={48} class="text-tertiary opacity-50 mb-2" />
+									<p class="text-sm font-semibold text-emphasis">Chat needs managed memory</p>
+									<p class="text-xs text-secondary max-w-xs">
+										{chatGap.memoryCanTurnOn
+											? 'Without it, every message would be answered without the ones before it.'
+											: 'This agent replays a fixed list of messages. Switch its memory to managed to chat with it.'}
+									</p>
+									{#if chatGap.memoryCanTurnOn && !readOnly}
+										<Button
+											unifiedSize="sm"
+											variant="default"
+											btnClasses="bg-surface mt-2"
+											onClick={turnOnMemory}
+										>
+											Turn on managed memory
+										</Button>
+									{/if}
+								</div>
+							{:else if chatGap?.noStream}
+								<div
+									class="shrink-0 flex items-center gap-2 px-4 py-1.5 border-b text-2xs text-secondary"
+								>
+									<Info size={12} class="shrink-0" />
+									<span class="flex-1">
+										{chatGap.noStream === 'image'
+											? 'Image answers do not stream: each one shows once its run ends.'
+											: 'Streaming is off: each answer shows once its run ends.'}
+									</span>
+									{#if chatGap.noStream === 'off' && !readOnly}
+										<Button unifiedSize="2xs" variant="subtle" onClick={turnOnStreaming}>
+											Turn on
+										</Button>
+									{/if}
+								</div>
+							{/if}
+							<!-- Hidden rather than unmounted while memory is off: switching it off mid-turn must
+							     not end the chat following that turn. Test chats, since what runs is the agent as
+							     edited. -->
+							<div class={chatGap?.memory ? 'hidden' : 'flex flex-col flex-1 min-h-0'}>
+								<FlowChat
+									onRunFlow={runChatTurn}
+									path={chatPath}
+									conversationKind="test"
+									subject="agent"
+									frame="none"
+									inputSchema={AGENT_CHAT_SCHEMA}
+									flowModules={chatModules}
+								/>
+							</div>
 						</div>
-					</Pane>
-					<Pane size={60} minSize={20}>
-						<ModulePreviewResultViewer
-							lang="deno"
-							editor={undefined}
-							diffEditor={undefined}
-							mod={agentModule as FlowModule}
-							{testJob}
-							{testIsLoading}
-							{scriptProgress}
-							disableMock
-							disableHistory
-						/>
-					</Pane>
-				</Splitpanes>
+					{/if}
+				</div>
 			</Pane>
 		</Splitpanes>
 	</div>
diff --git a/frontend/src/lib/components/flows/content/AgentEditorModal.svelte b/frontend/src/lib/components/flows/content/AgentEditorModal.svelte
index a6e113f39b..ea45761bf9 100644
--- a/frontend/src/lib/components/flows/content/AgentEditorModal.svelte
+++ b/frontend/src/lib/components/flows/content/AgentEditorModal.svelte
@@ -1,5 +1,7 @@
 <script lang="ts">
-	import { FlaskConical, History, Save } from 'lucide-svelte'
+	import { FlaskConical, FormInput, History, MessageSquare, Save } from 'lucide-svelte'
+	import ToggleButtonGroup from '$lib/components/common/toggleButton-v2/ToggleButtonGroup.svelte'
+	import ToggleButton from '$lib/components/common/toggleButton-v2/ToggleButton.svelte'
 	import { onDestroy, untrack } from 'svelte'
 	import { resource } from 'runed'
 	import Modal, { type ModalTrailSegment } from '$lib/components/common/modal/Modal.svelte'
@@ -93,6 +95,7 @@
 	})
 
 	let draft = $derived(host?.draftHandle())
+	let testPane = $derived(host?.testPaneHandle())
 	// The load refused this path, so there is no agent to deploy, evaluate or show a history of:
 	// the dialog carries only the refusal the host renders.
 	let refused = $derived(draft?.refusal != null)
@@ -268,6 +271,38 @@
 			{#snippet settings()}
 				<div class="flex flex-row items-center gap-2 shrink-0">
 					{#if !inEvals && !refused}
+						<!-- Switches the editor's right-hand pane, and is drawn only once the agent has
+						     loaded and the pane has picked its first mode. -->
+						{#if testPane?.mode}
+							<ToggleButtonGroup
+								bind:selected={
+									() => testPane?.mode,
+									(mode) => {
+										if (testPane) testPane.mode = mode
+									}
+								}
+								noWFull
+							>
+								{#snippet children({ item })}
+									<ToggleButton
+										size="sm"
+										value="chat"
+										label="Chat"
+										icon={MessageSquare}
+										tooltip="Chat with the agent: each message runs it, and it remembers the conversation"
+										{item}
+									/>
+									<ToggleButton
+										size="sm"
+										value="form"
+										label="Form"
+										icon={FormInput}
+										tooltip="Run the agent once, on the inputs in a form"
+										{item}
+									/>
+								{/snippet}
+							</ToggleButtonGroup>
+						{/if}
 						{#if readOnly}
 							<Badge
 								color="gray"
diff --git a/frontend/src/lib/components/flows/conversations/FlowChat.svelte b/frontend/src/lib/components/flows/conversations/FlowChat.svelte
index 52116991c6..01e2f60850 100644
--- a/frontend/src/lib/components/flows/conversations/FlowChat.svelte
+++ b/frontend/src/lib/components/flows/conversations/FlowChat.svelte
@@ -49,6 +49,9 @@
 		 * users have no test chats to look at.
 		 */
 		conversationKind?: 'test' | 'deployed'
+		/** What a message runs, as the chat names it. An agent has no deployed chats, so its
+		 *  sidebar offers no filter between those and the test ones. */
+		subject?: 'flow' | 'agent'
 	}
 
 	let {
@@ -62,7 +65,8 @@
 		description = undefined,
 		wideLayout = false,
 		frame = 'top',
-		conversationKind = 'deployed'
+		conversationKind = 'deployed',
+		subject = 'flow'
 	}: Props = $props()
 
 	const flowEditorContext = getContext<FlowEditorContext>('FlowEditorContext')
@@ -87,13 +91,13 @@
 			pollDelayMs: $enterpriseLicense ? 50 : undefined,
 			run: async ({ user_message, ...inputs }, { conversationId }) => {
 				const jobId = await onRunFlow(String(user_message), conversationId, inputs)
-				if (!jobId) throw new Error('the flow did not start')
+				if (!jobId) throw new Error(`the ${subject} did not start`)
 				// The server creates the conversation with the run, so the sidebar can list
 				// it now, whatever becomes of the turn.
 				sidebar?.conversationStarted(conversationId)
 				return jobId
 			},
-			onError: (error) => sendUserToast('Failed to run flow: ' + error.message, true)
+			onError: (error) => sendUserToast(`Failed to run ${subject}: ${error.message}`, true)
 		})
 		const unsubscribe = created.subscribe((s) => (chatState = s))
 		chat = created
@@ -126,7 +130,7 @@
 				{chat}
 				{chatState}
 				defaultKind={conversationKind}
-				canFilterKind={conversationKind !== 'deployed'}
+				canFilterKind={conversationKind !== 'deployed' && subject === 'flow'}
 			/>
 		{/if}
 		<!-- pb-3 on the chat alone, not on the row: the transcript and composer stop short of
@@ -147,6 +151,7 @@
 					{description}
 					{wideLayout}
 					{conversationKind}
+					{subject}
 				/>
 			{/key}
 		</div>
diff --git a/frontend/src/lib/components/flows/conversations/FlowChatInterface.svelte b/frontend/src/lib/components/flows/conversations/FlowChatInterface.svelte
index 2f5240d533..cad5688d89 100644
--- a/frontend/src/lib/components/flows/conversations/FlowChatInterface.svelte
+++ b/frontend/src/lib/components/flows/conversations/FlowChatInterface.svelte
@@ -44,6 +44,8 @@
 		wideLayout?: boolean
 		/** What this surface's runs create: previews in the editor, deployed runs on the flow page. */
 		conversationKind?: 'test' | 'deployed'
+		/** What a message runs, as the composer names it. */
+		subject?: 'flow' | 'agent'
 	}
 
 	let {
@@ -56,7 +58,8 @@
 		workspace = undefined,
 		description = undefined,
 		wideLayout = false,
-		conversationKind = 'deployed'
+		conversationKind = 'deployed',
+		subject = 'flow'
 	}: Props = $props()
 
 	// Derive helperScript for dynamic inputs from schema
@@ -91,7 +94,7 @@
 	const modelWiring = $derived(resolveAgentModelWiring(flowModules))
 	// An agent with nothing to call cannot answer, and the composer cannot fix it, so the
 	// chat says what to go and do instead of offering controls that write nowhere.
-	const modelGap = $derived(agentModelGap(modelWiring))
+	const modelGap = $derived(agentModelGap(modelWiring, subject))
 	const showModelButton = $derived(showsModelButton(modelWiring))
 
 	// LocalStorage helpers
@@ -273,7 +276,7 @@
 		{:else}
 			<MessageCircle size={48} class="mx-auto mb-4 opacity-50" />
 			<p class="text-lg font-medium">Start a conversation</p>
-			<p class="text-sm">Send a message to run the flow and see the results</p>
+			<p class="text-sm">Send a message to run the {subject} and see the results</p>
 			{#if !emptyString(description)}
 				<div class="mt-6 pt-4 border-t max-w-md text-left text-xs text-tertiary">
 					<GfmMarkdown md={description ?? ''} noPadding prose="sm" />
@@ -336,7 +339,7 @@
 		{wideLayout}
 		{emptyHint}
 		footerSettings={modalSchema || showModelButton ? footerSettings : undefined}
-		placeholder="Send a message to run the flow"
+		placeholder="Send a message to run the {subject}"
 		disabled={deploymentInProgress || !!modelGap || !!wrongKindReason}
 		disabledMessage={deploymentInProgress
 			? 'Deployment in progress'
diff --git a/frontend/src/lib/components/flows/conversations/agentChatInputs.ts b/frontend/src/lib/components/flows/conversations/agentChatInputs.ts
index 0ebaa9d918..1c178bde26 100644
--- a/frontend/src/lib/components/flows/conversations/agentChatInputs.ts
+++ b/frontend/src/lib/components/flows/conversations/agentChatInputs.ts
@@ -242,15 +242,19 @@ export function resolveAgentModelWiring(
  * about it, because no flow input feeds either field. Saying so beats a dead model button.
  * A field the flow exposes is never a gap: the reader picks it in the composer.
  */
-export function agentModelGap(wiring: AgentModelWiring | undefined): string | undefined {
+export function agentModelGap(
+	wiring: AgentModelWiring | undefined,
+	subject: 'flow' | 'agent' = 'flow'
+): string | undefined {
 	// No agent, several of them, or an expression we cannot read: not ours to judge.
 	if (!wiring || wiring.whole) return undefined
 	// Asked of each agent rather than of what they agree on: agents that merely disagree
 	// about the model all have one, and the message would be false — while an agent with
 	// an empty model still cannot run, however well the others are configured.
-	return wiring.someAgentCannotRun
-		? 'Pick a provider and model on the AI agent step to use this chat.'
-		: undefined
+	if (!wiring.someAgentCannotRun) return undefined
+	return subject === 'agent'
+		? 'Pick a provider and model for this agent to use this chat.'
+		: 'Pick a provider and model on the AI agent step to use this chat.'
 }
 
 /**
diff --git a/frontend/src/lib/components/flows/conversations/agentEditorChat.test.ts b/frontend/src/lib/components/flows/conversations/agentEditorChat.test.ts
new file mode 100644
index 0000000000..c00c1e4297
--- /dev/null
+++ b/frontend/src/lib/components/flows/conversations/agentEditorChat.test.ts
@@ -0,0 +1,76 @@
+import { describe, expect, it } from 'vitest'
+import type { FlowModule } from '$lib/gen'
+import { agentChatFlow, agentChatGap, agentChatPath } from './agentEditorChat'
+
+describe('agentChatPath', () => {
+	it('is a path no flow can take, so a same-path flow never shares its conversations', () => {
+		const flowPath = /^[ufg](\/[\w-]+){2,}$/
+		expect('f/support/agent').toMatch(flowPath)
+		expect(agentChatPath('f/support/agent')).not.toMatch(flowPath)
+	})
+})
+
+function agent(inputTransforms: Record<string, any>): FlowModule {
+	return {
+		id: '__wm_agent_root',
+		value: { type: 'aiagent', tools: [{ id: 't' }], input_transforms: inputTransforms }
+	} as unknown as FlowModule
+}
+
+describe('agentChatFlow', () => {
+	it('runs the agent in chat mode on the message and files, never on a step memory id', () => {
+		const flow = agentChatFlow(
+			agent({
+				system_prompt: { type: 'static', value: 'Be brief' },
+				user_message: { type: 'static', value: 'a default' },
+				memory_id: { type: 'static' },
+				previous_messages: { type: 'static' }
+			})
+		)
+		expect(flow.value.chat_input_enabled).toBe(true)
+		const step = flow.value.modules[0].value as any
+		expect(step.tools).toEqual([{ id: 't' }])
+		expect(step.input_transforms).toEqual({
+			system_prompt: { type: 'static', value: 'Be brief' },
+			user_message: { type: 'javascript', expr: 'flow_input.user_message' },
+			user_attachments: { type: 'javascript', expr: 'flow_input.user_attachments' }
+		})
+	})
+})
+
+describe('agentChatGap', () => {
+	it('is nothing to fix with managed memory and streaming left at its default', () => {
+		expect(
+			agentChatGap({ memory: { type: 'static', value: { kind: 'window', context_length: 10 } } })
+		).toBeUndefined()
+	})
+
+	it('reads an agent with no memory setting as off, and offers to turn it on', () => {
+		expect(agentChatGap({})).toEqual({ memory: true, memoryCanTurnOn: true, noStream: undefined })
+	})
+
+	it('flags memory off and streaming off', () => {
+		expect(
+			agentChatGap({
+				memory: { type: 'static', value: { kind: 'off' } },
+				streaming: { type: 'static', value: false }
+			})
+		).toEqual({ memory: true, memoryCanTurnOn: true, noStream: 'off' })
+	})
+
+	it('does not offer to replace a legacy manual memory', () => {
+		expect(
+			agentChatGap({ memory: { type: 'static', value: { kind: 'manual', messages: [] } } })
+		).toEqual({ memory: true, memoryCanTurnOn: false, noStream: undefined })
+	})
+
+	it('flags an image answer as never streaming, whatever the setting', () => {
+		expect(
+			agentChatGap({
+				memory: { type: 'static', value: { kind: 'window', context_length: 10 } },
+				output_type: { type: 'static', value: 'image' },
+				streaming: { type: 'static', value: true }
+			})
+		).toEqual({ memory: false, memoryCanTurnOn: false, noStream: 'image' })
+	})
+})
diff --git a/frontend/src/lib/components/flows/conversations/agentEditorChat.ts b/frontend/src/lib/components/flows/conversations/agentEditorChat.ts
new file mode 100644
index 0000000000..b754e04bb8
--- /dev/null
+++ b/frontend/src/lib/components/flows/conversations/agentEditorChat.ts
@@ -0,0 +1,101 @@
+import type { AiAgent, FlowModule, InputTransform, OpenFlow } from '$lib/gen'
+import { AGENT_FLOW_LOCAL_KEYS } from '../agentResourceUtils'
+import { agentMemoryMode, keepsManagedMemory } from '../agentFormFields'
+
+/**
+ * What an agent's chat runs, and files its conversations, under. Conversations are keyed by path
+ * alone, and a flow may share the agent's, so the suffix is one no flow path can carry (its
+ * segments are `[\w-]`): otherwise each would list the other's chats, and continuing one would run
+ * a step that never saw its memory. The first two segments, which the server checks a preview
+ * run's path against, stay the agent's.
+ */
+export function agentChatPath(agentPath: string): string {
+	return `${agentPath}.chat`
+}
+
+/**
+ * The inputs of the flow a saved agent is chatted with: the message, and the files the composer's
+ * paperclip uploads. `user_message` is the name the server requires of a chat-mode run.
+ */
+export const AGENT_CHAT_SCHEMA = {
+	$schema: 'https://json-schema.org/draft/2020-12/schema',
+	type: 'object',
+	properties: {
+		user_message: { type: 'string', description: 'Message from user' },
+		user_attachments: {
+			type: 'array',
+			items: { type: 'object', resourceType: 's3object' },
+			description: 'Images or PDFs for the agent to read'
+		}
+	},
+	required: ['user_message']
+}
+
+/**
+ * The chat-mode flow one turn of the agent editor's chat runs: the agent as edited, alone, reading
+ * the message and files from the chat. Every other flow-local input is dropped, `memory_id` above
+ * all: a step memory id, even an empty one, would replace the conversation's and the agent would
+ * not remember the turns before.
+ */
+export function agentChatFlow(agent: FlowModule): OpenFlow {
+	const value = agent.value as AiAgent
+	const brain = Object.fromEntries(
+		Object.entries(value.input_transforms ?? {}).filter(
+			([key]) => !(AGENT_FLOW_LOCAL_KEYS as readonly string[]).includes(key)
+		)
+	)
+	return {
+		summary: '',
+		value: {
+			chat_input_enabled: true,
+			modules: [
+				{
+					id: agent.id,
+					value: {
+						...value,
+						input_transforms: {
+							...brain,
+							user_message: { type: 'javascript', expr: 'flow_input.user_message' },
+							user_attachments: { type: 'javascript', expr: 'flow_input.user_attachments' }
+						} as AiAgent['input_transforms']
+					}
+				}
+			]
+		},
+		schema: AGENT_CHAT_SCHEMA
+	}
+}
+
+/** What the agent as configured takes away from a chat. */
+export type AgentChatGap = {
+	/** No managed memory: every message would be answered without the ones before it, so the
+	 *  chat is not offered at all. */
+	memory: boolean
+	/** Whether turning memory on is a plain switch, rather than replacing an older manual list. */
+	memoryCanTurnOn: boolean
+	/** Why a turn shows nothing until its run ends: streaming switched off, or an image answer,
+	 *  which the worker never streams whatever the setting. */
+	noStream: 'off' | 'image' | undefined
+}
+
+function staticValue(transform: InputTransform | undefined): unknown {
+	return transform?.type === 'static' ? transform.value : undefined
+}
+
+export function agentChatGap(
+	transforms: Record<string, InputTransform> | undefined
+): AgentChatGap | undefined {
+	const memory = staticValue(transforms?.['memory'])
+	const gap: AgentChatGap = {
+		memory: !keepsManagedMemory(memory),
+		memoryCanTurnOn: agentMemoryMode(memory) === 'off',
+		noStream:
+			staticValue(transforms?.['output_type']) === 'image'
+				? 'image'
+				: // Unset streams: it is on by default.
+					staticValue(transforms?.['streaming']) === false
+					? 'off'
+					: undefined
+	}
+	return gap.memory || gap.noStream ? gap : undefined
+}