diff --git a/frontend/src/lib/common.ts b/frontend/src/lib/common.ts
index 94d2090665..9bd03af131 100644
--- a/frontend/src/lib/common.ts
+++ b/frontend/src/lib/common.ts
@@ -46,6 +46,7 @@ export interface SchemaProperty {
 	title?: string
 	placeholder?: string
 	oneOf?: SchemaProperty[]
+	originalType?: string
 }
 
 export interface ModalSchemaProperty {
diff --git a/frontend/src/lib/components/StringTypeNarrowing.svelte b/frontend/src/lib/components/StringTypeNarrowing.svelte
index 40e3b645eb..76acf833e4 100644
--- a/frontend/src/lib/components/StringTypeNarrowing.svelte
+++ b/frontend/src/lib/components/StringTypeNarrowing.svelte
@@ -24,8 +24,8 @@
 	export let noExtra = false
 	export let dateFormat: string | undefined
 	export let enumLabels: Record<string, string> = {}
-	export let allowKindChange: boolean = true
-	export let allowAddingOrDeletingEnumValues: boolean = true
+	export let overrideAllowKindChange: boolean = true
+	export let originalType: string | undefined = undefined
 
 	let kind: 'none' | 'pattern' | 'enum' | 'resource' | 'format' | 'base64' = computeKind(
 		enum_,
@@ -34,6 +34,8 @@
 		format
 	)
 
+	const allowKindChange = overrideAllowKindChange || originalType === 'string'
+
 	let patternStr: string = pattern ?? ''
 	let resource: string | undefined
 
@@ -204,13 +206,13 @@
 							/>
 						{/if}
 
-						{#if allowAddingOrDeletingEnumValues}
+						{#if allowKindChange}
 							<Button size="sm" on:click={() => remove(e)}>-</Button>
 						{/if}
 					</div>
 				{/each}
 			</div>
-			{#if allowAddingOrDeletingEnumValues}
+			{#if allowKindChange}
 				<div class="flex flex-row my-1">
 					<Button color="light" size="sm" on:click={add}>+</Button>
 				</div>
diff --git a/frontend/src/lib/components/schema/PropertyEditor.svelte b/frontend/src/lib/components/schema/PropertyEditor.svelte
index aa22a360c3..0d81460ead 100644
--- a/frontend/src/lib/components/schema/PropertyEditor.svelte
+++ b/frontend/src/lib/components/schema/PropertyEditor.svelte
@@ -148,8 +148,8 @@
 								bind:disableVariablePicker={extra['disableVariablePicker']}
 								bind:dateFormat={extra['dateFormat']}
 								bind:enumLabels={extra['enumLabels']}
-								allowKindChange={isFlowInput || isAppInput}
-								allowAddingOrDeletingEnumValues={isFlowInput || isAppInput}
+								originalType={extra['originalType']}
+								overrideAllowKindChange={isFlowInput || isAppInput}
 							/>
 						{:else if type == 'number' || type == 'integer'}
 							<NumberTypeNarrowing
diff --git a/frontend/src/lib/inferArgSig.ts b/frontend/src/lib/inferArgSig.ts
index bc6a7c3dea..c54cce752a 100644
--- a/frontend/src/lib/inferArgSig.ts
+++ b/frontend/src/lib/inferArgSig.ts
@@ -36,6 +36,7 @@ export function argSigToJsonSchemaType(
 	} else if (t === 'bytes') {
 		newS.type = 'string'
 		newS.contentEncoding = 'base64'
+		newS.originalType = 'bytes'
 	} else if (t === 'datetime') {
 		newS.type = 'string'
 		newS.format = 'date-time'
@@ -78,8 +79,10 @@ export function argSigToJsonSchemaType(
 	} else if (typeof t !== 'string' && `str` in t) {
 		newS.type = 'string'
 		if (t.str) {
+			newS.originalType = 'enum'
 			newS.enum = t.str
 		} else {
+			newS.originalType = 'string'
 			newS.enum = undefined
 		}
 	} else if (typeof t !== 'string' && `resource` in t) {