diff --git a/backend/windmill-ai/src/types.rs b/backend/windmill-ai/src/types.rs
index fd09013486..f250c09606 100644
--- a/backend/windmill-ai/src/types.rs
+++ b/backend/windmill-ai/src/types.rs
@@ -85,7 +85,7 @@ pub enum Memory {
     Auto {
         #[serde(default)]
         context_length: usize,
-        #[serde(default)]
+        #[serde(default, deserialize_with = "deserialize_blank_as_none")]
         memory_id: Option<Uuid>,
     },
     /// Written before the step's `messages` input, which it is equivalent to.
@@ -94,6 +94,19 @@ pub enum Memory {
     },
 }
 
+// An editor form can leave `""` in a legacy baked id it never filled; it means no id rather than
+// failing every run of the step.
+fn deserialize_blank_as_none<'de, D: serde::Deserializer<'de>>(
+    deserializer: D,
+) -> Result<Option<Uuid>, D::Error> {
+    match <Option<String> as serde::Deserialize>::deserialize(deserializer)? {
+        Some(id) if !id.trim().is_empty() => Uuid::parse_str(id.trim())
+            .map(Some)
+            .map_err(serde::de::Error::custom),
+        _ => Ok(None),
+    }
+}
+
 fn deserialize_present_messages<'de, D: serde::Deserializer<'de>>(
     deserializer: D,
 ) -> Result<Option<Option<Vec<OpenAIMessage>>>, D::Error> {
diff --git a/backend/windmill-worker/src/ai_executor.rs b/backend/windmill-worker/src/ai_executor.rs
index e1a931bf7e..11a1b52f91 100644
--- a/backend/windmill-worker/src/ai_executor.rs
+++ b/backend/windmill-worker/src/ai_executor.rs
@@ -1978,6 +1978,18 @@ mod tests {
                 None,
                 Resolved::Window(baked, 4),
             ),
+            (
+                "legacy auto with an empty baked id uses the run's",
+                json!({ "memory": { "kind": "auto", "context_length": 4, "memory_id": "" } }),
+                Some(run),
+                Resolved::Window(run, 4),
+            ),
+            (
+                "legacy auto with an empty baked id and no run id is stateless",
+                json!({ "memory": { "kind": "auto", "context_length": 4, "memory_id": " " } }),
+                None,
+                Resolved::Stateless { noted: true },
+            ),
             (
                 "legacy auto without a length is off",
                 json!({ "memory": { "kind": "auto", "memory_id": baked } }),
diff --git a/frontend/src/lib/components/flows/agentFormFields.test.ts b/frontend/src/lib/components/flows/agentFormFields.test.ts
index d3112beb3b..ebdd1ef4ac 100644
--- a/frontend/src/lib/components/flows/agentFormFields.test.ts
+++ b/frontend/src/lib/components/flows/agentFormFields.test.ts
@@ -115,5 +115,10 @@ describe('memoryPropertyFor', () => {
 			'auto'
 		])
 		expect(kinds({ kind: 'manual', messages: [] })).toEqual(['off', 'window', 'manual'])
+		const autoVariant = (value: unknown) => memoryPropertyFor(property, value).oneOf.at(-1)
+		expect(autoVariant({ kind: 'auto', context_length: 4 }).properties.memory_id).toBeUndefined()
+		expect(
+			autoVariant({ kind: 'auto', context_length: 4, memory_id: 'x' }).properties.memory_id
+		).toBeDefined()
 	})
 })
diff --git a/frontend/src/lib/components/flows/flowInfers.ts b/frontend/src/lib/components/flows/flowInfers.ts
index 8a344a370d..bd2c1f8e40 100644
--- a/frontend/src/lib/components/flows/flowInfers.ts
+++ b/frontend/src/lib/components/flows/flowInfers.ts
@@ -213,8 +213,15 @@ export const LEGACY_MEMORY_VARIANTS: Record<string, any> = {
  *  value holds it. Otherwise the property itself is returned, which callers compare by identity to
  *  avoid rebuilding the step schema. */
 export function memoryPropertyFor(property: any, value: any): any {
-	const legacy = value?.kind ? LEGACY_MEMORY_VARIANTS[value.kind] : undefined
+	let legacy = value?.kind ? LEGACY_MEMORY_VARIANTS[value.kind] : undefined
 	if (!legacy || !property?.oneOf) return property
+	// The form fills an empty string field with `''` when it opens, so the baked id field is only
+	// offered to a value saved with the key. Keyed on presence rather than content, or clearing the
+	// id to retype it would remove the field mid-edit.
+	if (value.kind === 'auto' && !('memory_id' in value)) {
+		const { memory_id: _, ...properties } = legacy.properties
+		legacy = { ...legacy, properties }
+	}
 	return { ...property, oneOf: [...property.oneOf, legacy] }
 }
 
diff --git a/frontend/src/lib/components/flows/utils.svelte.ts b/frontend/src/lib/components/flows/utils.svelte.ts
index c6d625e28e..17afa2c6c6 100644
--- a/frontend/src/lib/components/flows/utils.svelte.ts
+++ b/frontend/src/lib/components/flows/utils.svelte.ts
@@ -163,10 +163,10 @@ export function normalizeAgentHistory(
 	if (!inputTransforms) return
 	const memory = inputTransforms.memory
 	if (
-		chatInputEnabled &&
 		memory?.type === 'static' &&
 		memory.value?.kind === 'auto' &&
-		memory.value.memory_id
+		'memory_id' in memory.value &&
+		(chatInputEnabled || !String(memory.value.memory_id ?? '').trim())
 	) {
 		const { memory_id: _, ...policy } = memory.value
 		memory.value = policy
diff --git a/frontend/src/lib/components/flows/utils.test.ts b/frontend/src/lib/components/flows/utils.test.ts
index 7239986879..04b24a7cc7 100644
--- a/frontend/src/lib/components/flows/utils.test.ts
+++ b/frontend/src/lib/components/flows/utils.test.ts
@@ -70,6 +70,14 @@ describe('normalizeAgentHistory', () => {
 		expect(transforms.memory.value).toEqual({ kind: 'auto', context_length: 10 })
 	})
 
+	it('drops an empty baked memory id, which names no memory', () => {
+		const transforms = {
+			memory: { type: 'static', value: { kind: 'auto', context_length: 10, memory_id: '' } }
+		}
+		normalizeAgentHistory(transforms, false)
+		expect(transforms.memory.value).toEqual({ kind: 'auto', context_length: 10 })
+	})
+
 	it('does not persist an empty static memory id or message list', () => {
 		const transforms: Record<string, any> = {
 			memory_id: { type: 'static', value: ' ' },