fix: offer no memory id for legacy manual memory, document linked history inputs

backend/windmill-worker/src/ai_executor.rs

@@ -453,9 +453,9 @@ pub async fn handle_ai_agent_job(
         ));
     };
 
-    // A linked step takes its brain and tools from the resource and keeps only the flow-local
-    // inputs (user message, attachments, memory id and messages) of its own; both stay rigid, so the one thing it may
-    // bind to this flow is the tools' inputs, overlaid from `tool_inputs` below.
+    // A linked step takes its brain and tools from the resource and keeps only the flow-local inputs
+    // (user message, attachments, memory id and messages) of its own; both stay rigid, so the one
+    // thing it may bind to this flow is the tools' inputs, overlaid from `tool_inputs` below.
     let (mut args, tools): (AIAgentArgs, Vec<AgentTool>) = if let Some(agent_ref) = agent.as_deref()
     {
         let agent_path = agent_ref

docs/reusable-ai-agents.md

@@ -65,7 +65,8 @@ The worker reconciles them once per agent invocation, nested agent tools include
 
 Memory is stored per (memory id, step id), in `ai_agent_memory` or S3 at
 `memory/{workspace}/{memory id}/{step}.json`. The chat transcript (`flow_conversation_message`)
-always follows the run's id, even when a step sets its own.
+always follows the run's id, even when a step sets its own. Nothing expires stored memory: deleting a chat conversation deletes
+its memory, and a memory named by a string id stays until it is overwritten.
 
 Compatibility runs one way. New workers read every older shape. The editor rewrites a legacy step
 only when the author changes it, so a flow nobody edits keeps running on older workers, while a

frontend/src/lib/components/flows/agentFormFields.test.ts

@@ -4,6 +4,7 @@ import {
 	AGENT_FIELD_BY_KEY,
 	AGENT_FIELDS,
 	AGENT_HISTORY_KEYS,
+	memoryIdUnusedNote,
 	agentFieldIsSet,
 	agentStreamingEnabled,
 	initialVisibleAgentFields
@@ -127,3 +128,16 @@ describe('agentStreamingEnabled', () => {
 		).toBe(false)
 	})
 })
+
+describe('memoryIdUnusedNote', () => {
+	// Mirrors the worker's order: offering a memory id that a run would ignore misleads the author.
+	it('offers a memory id only when the policy reads memory', () => {
+		expect(memoryIdUnusedNote(undefined)).toMatch(/off/)
+		expect(memoryIdUnusedNote({ kind: 'off' })).toMatch(/off/)
+		expect(memoryIdUnusedNote({ kind: 'window', context_length: 0 })).toMatch(/off/)
+		expect(memoryIdUnusedNote({ kind: 'auto' })).toMatch(/off/)
+		expect(memoryIdUnusedNote({ kind: 'manual', messages: [] })).toMatch(/fixed list/)
+		expect(memoryIdUnusedNote({ kind: 'window', context_length: 10 })).toBeUndefined()
+		expect(memoryIdUnusedNote({ kind: 'auto', context_length: 4, memory_id: 'x' })).toBeUndefined()
+	})
+})

frontend/src/lib/components/flows/agentFormFields.ts

@@ -44,6 +44,19 @@ export function memoryPolicyIsOff(memory: any): boolean {
 	return false
 }
 
+/** Why a step's history row offers no memory id, when it offers none: the agent keeps no memory, or
+ *  its memory setting supplies a fixed list of messages, which the worker sends before it would
+ *  read any memory. */
+export function memoryIdUnusedNote(memory: any): string | undefined {
+	if (memory?.kind === 'manual') {
+		return 'This agent sends a fixed list of messages set in its memory, so no memory id applies.'
+	}
+	if (memoryPolicyIsOff(memory)) {
+		return "This agent's memory is off, so no memory id applies. Turn memory on in the agent to change this."
+	}
+	return undefined
+}
+
 /** A memory setting in words, for a linked agent's summary. */
 export function describeMemoryPolicy(memory: any): string {
 	if (memory?.kind === 'manual') return 'Provided messages'

frontend/src/lib/components/flows/agentResourceUtils.ts

@@ -121,7 +121,8 @@ export function inputTransformsToAgentConfig(
 
 /**
  * Reduce the AI agent schema to only the flow-local inputs. Used when a step is linked to a saved
- * agent: the brain fields come from the resource, so only user_message/user_attachments stay editable.
+ * agent: the brain fields come from the resource, so only the user message, attachments and history
+ * inputs stay editable.
  */
 export function flowLocalAgentSchema(schema: any): any {
 	if (!schema?.properties) {

frontend/src/lib/components/flows/content/AgentHistoryInput.svelte

@@ -14,8 +14,8 @@
 		label: string
 		tooltip?: string
 		chatInputEnabled?: boolean
-		/** The agent keeps no memory, so no memory id applies to this step. */
-		memoryOff?: boolean
+		/** Why no memory id applies to this step, when the agent reads no memory. */
+		memoryUnusedNote?: string
 		/** The step's editor for one history input, with the error to show under it. */
 		field: Snippet<[AgentHistoryKey, string | undefined]>
 		/** Called for each key this row removes, so the form forgets its validity. */
@@ -27,7 +27,7 @@
 		label,
 		tooltip = undefined,
 		chatInputEnabled = false,
-		memoryOff = false,
+		memoryUnusedNote = undefined,
 		field,
 		onRemoveKey = undefined
 	}: Props = $props()
@@ -58,11 +58,8 @@
 	<div class="flex min-h-7 items-end">
 		<FieldHeader {label} simpleTooltip={tooltip} displayType={false} />
 	</div>
-	{#if memoryOff}
-		<p class="text-xs text-secondary">
-			This agent's memory is off, so no memory id applies. Turn memory on in the agent to change
-			this.
-		</p>
+	{#if memoryUnusedNote}
+		<p class="text-xs text-secondary">{memoryUnusedNote}</p>
 		{#if source === 'here'}
 			<div class="flex items-center gap-2">
 				<Badge color="yellow" small>Ignored</Badge>

frontend/src/lib/components/flows/content/AiAgentStepInputs.svelte

@@ -41,7 +41,7 @@
 		AGENT_FIELDS,
 		AGENT_HISTORY_ROW,
 		AGENT_TOOLS_ROW,
-		memoryPolicyIsOff,
+		memoryIdUnusedNote,
 		AGENT_FIELD_GROUPS,
 		agentFieldAppliesTo,
 		initialVisibleAgentFields,
@@ -164,14 +164,14 @@
 
 	// The brain edited here, or the linked agent's. An expression, or a linked agent still loading,
 	// reads as keeping memory, so the history row never offers less than a run may use.
-	let memoryOff = $derived.by(() => {
+	let memoryUnusedNote = $derived.by(() => {
 		if ('memory' in schemaProperties) {
 			const transform = args?.memory
 			return transform == undefined || transform.type === 'static'
-				? memoryPolicyIsOff(transform?.value)
-				: false
+				? memoryIdUnusedNote(transform?.value)
+				: undefined
 		}
-		return linkedMemory ? memoryPolicyIsOff(linkedMemory.memory) : false
+		return linkedMemory ? memoryIdUnusedNote(linkedMemory.memory) : undefined
 	})
 
 	let scopedFields = $derived(
@@ -415,7 +415,7 @@
 												label={spec.label}
 												tooltip={spec.tooltip}
 												{chatInputEnabled}
-												{memoryOff}
+												{memoryUnusedNote}
 												onRemoveKey={(key) => delete inputCheck[key]}
 											>
 												{#snippet field(key, error)}

openflow.openapi.yaml

@@ -1155,7 +1155,7 @@ components:
             Path of a reusable `ai_agent` resource (hybrid linking). When set, the agent brain
             config (provider/model/system prompt/etc.) and tool set are resolved at runtime from
             that resource; the module's input_transforms then only carry the flow-local inputs
-            (user_message/user_attachments).
+            (user_message, user_attachments and the history inputs memory_id and messages).
         tool_inputs:
           type: object
           description: |