diff --git a/frontend/src/lib/common.ts b/frontend/src/lib/common.ts
index 3d829003b2..2a7830eaa4 100644
--- a/frontend/src/lib/common.ts
+++ b/frontend/src/lib/common.ts
@@ -28,10 +28,41 @@ export interface SchemaProperty {
 		contentEncoding?: 'base64'
 		enum?: string[]
 	}
+	customErrorMessage?: string
 	properties?: { [name: string]: SchemaProperty }
 	required?: string[]
 }
 
+export interface ModalSchemaProperty {
+	selectedType?: string
+	description: string
+	name: string
+	required: boolean
+	format?: string
+	pattern?: string
+	enum_?: string[]
+	default?: any
+	items?: { type?: 'string' | 'number' }
+	contentEncoding?: 'base64' | 'binary'
+	schema?: Schema
+	customErrorMessage?: string
+}
+
+export function modalToSchema(schema: ModalSchemaProperty): SchemaProperty {
+	return {
+		type: schema.selectedType,
+		description: schema.description,
+		pattern: schema.pattern,
+		default: schema.default,
+		enum: schema.enum_,
+		items: schema.items,
+		contentEncoding: schema.contentEncoding,
+		format: schema.format,
+		customErrorMessage: schema.customErrorMessage,
+		properties: schema.schema?.properties,
+		required: schema.schema?.required
+	}
+}
 export type Schema = {
 	$schema: string | undefined
 	type: string
diff --git a/frontend/src/lib/components/ArgInput.svelte b/frontend/src/lib/components/ArgInput.svelte
index 3ea5436a8e..ff67e061f6 100644
--- a/frontend/src/lib/components/ArgInput.svelte
+++ b/frontend/src/lib/components/ArgInput.svelte
@@ -1,6 +1,6 @@
 <script lang="ts">
 	import type { SchemaProperty } from '$lib/common'
-	import { setInputCat as computeInputCat } from '$lib/utils'
+	import { setInputCat as computeInputCat, emptyString } from '$lib/utils'
 	import { ChevronDown, DollarSign, Plus, X } from 'lucide-svelte'
 	import { createEventDispatcher } from 'svelte'
 	import autosize from 'svelte-autosize'
@@ -66,6 +66,7 @@
 	export let disablePortal = false
 	export let showSchemaExplorer = false
 	export let simpleTooltip: string | undefined = undefined
+	export let customErrorMessage: string | undefined = undefined
 
 	let seeEditable: boolean = enum_ != undefined || pattern != undefined
 	const dispatch = createEventDispatcher()
@@ -150,7 +151,13 @@
 			valid && (valid = false)
 		} else {
 			if (pattern && !testRegex(pattern, v)) {
-				error = `Should match ${pattern}`
+				if (!emptyString(customErrorMessage)) {
+					error = customErrorMessage ?? ''
+				} else if (format == 'email') {
+					error = 'invalid email address'
+				} else {
+					error = `Should match ${pattern}`
+				}
 				valid && (valid = false)
 			} else {
 				error = ''
@@ -234,7 +241,13 @@
 					{#if seeEditable}
 						<div class="mt-2">
 							{#if type == 'string' && format != 'date-time'}
-								<StringTypeNarrowing bind:format bind:pattern bind:enum_ bind:contentEncoding />
+								<StringTypeNarrowing
+									bind:customErrorMessage
+									bind:format
+									bind:pattern
+									bind:enum_
+									bind:contentEncoding
+								/>
 							{:else if type == 'number'}
 								<NumberTypeNarrowing bind:min={extra['min']} bind:max={extra['max']} />
 							{:else if type == 'object'}
@@ -446,6 +459,18 @@
 						: undefined}
 					{showSchemaExplorer}
 				/>
+			{:else if inputCat == 'email'}
+				<input
+					{autofocus}
+					on:focus
+					{disabled}
+					type="email"
+					class={valid
+						? ''
+						: 'border border-red-700 border-opacity-30 focus:border-red-700 focus:border-opacity-3'}
+					placeholder={defaultValue ?? ''}
+					bind:value
+				/>
 			{:else if inputCat == 'string'}
 				<div class="flex flex-col w-full">
 					<div class="flex flex-row w-full items-center justify-between relative">
@@ -467,7 +492,7 @@
 									'w-full',
 									valid
 										? ''
-										: 'border border-red-700 border-opacity-30 focus:border-red-700 focus:border-opacity-30 bg-red-100'
+										: 'border border-red-700 border-opacity-30 focus:border-red-700 focus:border-opacity-3'
 								)}
 								placeholder={defaultValue ?? ''}
 								bind:value
diff --git a/frontend/src/lib/components/LightweightArgInput.svelte b/frontend/src/lib/components/LightweightArgInput.svelte
index a657fcbb85..aaa7c290ee 100644
--- a/frontend/src/lib/components/LightweightArgInput.svelte
+++ b/frontend/src/lib/components/LightweightArgInput.svelte
@@ -1,5 +1,5 @@
 <script lang="ts">
-	import { setInputCat as computeInputCat } from '$lib/utils'
+	import { setInputCat as computeInputCat, emptyString } from '$lib/utils'
 	import { Badge, Button } from './common'
 	import { createEventDispatcher } from 'svelte'
 	import FieldHeader from './FieldHeader.svelte'
@@ -43,13 +43,12 @@
 	export let nestedRequired: string[] | undefined = undefined
 	export let extra: Record<string, any> = {}
 	export let displayType: boolean = true
+	export let customErrorMessage: string | undefined = undefined
 
 	const dispatch = createEventDispatcher()
 
 	$: maxHeight = maxRows ? `${1 + maxRows * 1.2}em` : `auto`
 
-	$: validateInput(pattern, value)
-
 	export let error: string = ''
 
 	let el: HTMLTextAreaElement | undefined = undefined
@@ -68,10 +67,8 @@
 	}
 
 	$: {
-		error = ''
 		if (inputCat === 'object') {
 			evalValueToRaw()
-			validateInput(pattern, value)
 		}
 	}
 
@@ -102,17 +99,23 @@
 		}
 	}
 
-	function validateInput(pattern: string | undefined, v: any): void {
+	function validateInput(pattern: string | undefined, v: any, required: boolean): void {
 		if (required && (v == undefined || v == null || v === '')) {
 			error = 'Required'
-			valid = false
+			valid && (valid = false)
 		} else {
 			if (pattern && !testRegex(pattern, v)) {
-				error = `Should match ${pattern}`
-				valid = false
+				if (!emptyString(customErrorMessage)) {
+					error = customErrorMessage ?? ''
+				} else if (format == 'email') {
+					error = 'invalid email address'
+				} else {
+					error = `should match ${pattern}`
+				}
+				valid && (valid = false)
 			} else {
 				error = ''
-				valid = true
+				!valid && (valid = true)
 			}
 		}
 	}
@@ -141,6 +144,8 @@
 		}
 	}
 
+	$: validateInput(pattern, value, required)
+
 	$: inputCat = computeInputCat(type, format, itemsType?.type, enum_, contentEncoding)
 </script>
 
@@ -209,47 +214,51 @@
 			{:else if inputCat == 'list'}
 				<div class="w-full">
 					<div class="w-full">
-						{#each value ?? [] as v, i}
-							<div class="flex flex-row max-w-md mt-1 w-full">
-								{#if itemsType?.type == 'number'}
-									<input type="number" bind:value={v} />
-								{:else if itemsType?.type == 'string' && itemsType?.contentEncoding == 'base64'}
-									<input
-										type="file"
-										class="my-6"
-										on:change={(x) => fileChanged(x, (val) => (value[i] = val))}
-										multiple={false}
-									/>
-								{:else if Array.isArray(itemsType?.enum)}
-									<select
-										on:focus={(e) => {
-											dispatch('focus')
+						{#if Array.isArray(value)}
+							{#each value ?? [] as v, i}
+								<div class="flex flex-row max-w-md mt-1 w-full">
+									{#if itemsType?.type == 'number'}
+										<input type="number" bind:value={v} />
+									{:else if itemsType?.type == 'string' && itemsType?.contentEncoding == 'base64'}
+										<input
+											type="file"
+											class="my-6"
+											on:change={(x) => fileChanged(x, (val) => (value[i] = val))}
+											multiple={false}
+										/>
+									{:else if Array.isArray(itemsType?.enum)}
+										<select
+											on:focus={(e) => {
+												dispatch('focus')
+											}}
+											class="px-6"
+											bind:value={v}
+										>
+											{#each itemsType?.enum ?? [] as e}
+												<option>{e}</option>
+											{/each}
+										</select>
+									{:else}
+										<input type="text" bind:value={v} />
+									{/if}
+									<button
+										transition:fade|local={{ duration: 100 }}
+										class="rounded-full p-1 bg-surface-secondary duration-200 hover:bg-surface-hover ml-2"
+										aria-label="Clear"
+										on:click={() => {
+											value = value.filter((el) => el != v)
+											if (value.length == 0) {
+												value = undefined
+											}
 										}}
-										class="px-6"
-										bind:value={v}
 									>
-										{#each itemsType?.enum ?? [] as e}
-											<option>{e}</option>
-										{/each}
-									</select>
-								{:else}
-									<input type="text" bind:value={v} />
-								{/if}
-								<button
-									transition:fade|local={{ duration: 100 }}
-									class="rounded-full p-1 bg-surface-secondary duration-200 hover:bg-surface-hover ml-2"
-									aria-label="Clear"
-									on:click={() => {
-										value = value.filter((el) => el != v)
-										if (value.length == 0) {
-											value = undefined
-										}
-									}}
-								>
-									<X size={14} />
-								</button>
-							</div>
-						{/each}
+										<X size={14} />
+									</button>
+								</div>
+							{/each}
+						{:else}
+							List is not an array
+						{/if}
 					</div>
 					<div class="flex my-2">
 						<Button
@@ -269,7 +278,7 @@
 						</Button>
 					</div>
 					<span class="ml-2">
-						{(value ?? []).length} item{(value ?? []).length > 1 ? 's' : ''}
+						{(value ?? []).length} item{(value ?? []).length != 1 ? 's' : ''}
 					</span>
 				</div>
 			{:else if inputCat == 'resource-object'}
@@ -312,12 +321,16 @@
 			{:else if inputCat == 'date'}
 				<DateTimeInput bind:value />
 			{:else if inputCat == 'base64'}
-				<input
-					type="file"
-					class="my-6"
-					on:change={(x) => fileChanged(x, (val) => (value = val))}
-					multiple={false}
-				/>
+				<div class="flex flex-col my-6 w-full">
+					<input
+						type="file"
+						on:change={(x) => fileChanged(x, (val) => (value = val))}
+						multiple={false}
+					/>
+					{#if value?.length}
+						<div class="text-2xs text-tertiary mt-1">File length: {value.length} base64 chars</div>
+					{/if}
+				</div>
 			{:else if inputCat == 'resource-string'}
 				<div class="flex flex-row gap-x-1 w-full">
 					<LightweightResourcePicker
@@ -327,6 +340,16 @@
 							: undefined}
 					/>
 				</div>
+			{:else if inputCat == 'email'}
+				<input
+					on:focus
+					type="email"
+					class={valid
+						? ''
+						: 'border border-red-700 border-opacity-30 focus:border-red-700 focus:border-opacity-3'}
+					placeholder={defaultValue ?? ''}
+					bind:value
+				/>
 			{:else if inputCat == 'string'}
 				<div class="flex flex-col w-full">
 					<div class="flex flex-row w-full items-center justify-between">
diff --git a/frontend/src/lib/components/LightweightSchemaForm.svelte b/frontend/src/lib/components/LightweightSchemaForm.svelte
index fdaceff84e..be9ae2ff18 100644
--- a/frontend/src/lib/components/LightweightSchemaForm.svelte
+++ b/frontend/src/lib/components/LightweightSchemaForm.svelte
@@ -75,6 +75,7 @@
 				enum_={schema.properties[argName].enum}
 				format={schema.properties[argName].format}
 				contentEncoding={schema.properties[argName].contentEncoding}
+				customErrorMessage={schema.properties[argName].customErrorMessage}
 				properties={schema.properties[argName].properties}
 				nestedRequired={schema.properties[argName].required}
 				itemsType={schema.properties[argName].items}
diff --git a/frontend/src/lib/components/SchemaEditor.svelte b/frontend/src/lib/components/SchemaEditor.svelte
index ea2598ae1d..f0c1eca492 100644
--- a/frontend/src/lib/components/SchemaEditor.svelte
+++ b/frontend/src/lib/components/SchemaEditor.svelte
@@ -1,9 +1,14 @@
 <script lang="ts">
-	import type { Schema, SchemaProperty, PropertyDisplayInfo } from '$lib/common'
+	import {
+		type Schema,
+		type SchemaProperty,
+		type PropertyDisplayInfo,
+		modalToSchema,
+		type ModalSchemaProperty
+	} from '$lib/common'
 	import { emptySchema, emptyString, sendUserToast } from '$lib/utils'
 	import { Button } from './common'
 	import { createEventDispatcher } from 'svelte'
-	import type { ModalSchemaProperty } from './SchemaModal.svelte'
 	import SchemaModal, { DEFAULT_PROPERTY, schemaToModal } from './SchemaModal.svelte'
 	import PropertyRow from './PropertyRow.svelte'
 	import SimpleEditor from './SimpleEditor.svelte'
@@ -79,20 +84,6 @@
 		}
 	}
 
-	function modalToSchema(schema: ModalSchemaProperty): SchemaProperty {
-		return {
-			type: schema.selectedType,
-			description: schema.description,
-			pattern: schema.pattern,
-			default: schema.default,
-			enum: schema.enum_,
-			items: schema.items,
-			contentEncoding: schema.contentEncoding,
-			format: schema.format,
-			properties: schema.schema?.properties,
-			required: schema.schema?.required
-		}
-	}
 	function handleAddOrEditArgument(modalProperty: ModalSchemaProperty): void {
 		// If editing the arg's name, oldName containing the old argument name must be provided
 		argError = ''
diff --git a/frontend/src/lib/components/SchemaForm.svelte b/frontend/src/lib/components/SchemaForm.svelte
index 2aac841003..2e2b11d6bc 100644
--- a/frontend/src/lib/components/SchemaForm.svelte
+++ b/frontend/src/lib/components/SchemaForm.svelte
@@ -102,6 +102,7 @@
 								bind:enum_={schema.properties[argName].enum}
 								bind:format={schema.properties[argName].format}
 								bind:contentEncoding={schema.properties[argName].contentEncoding}
+								bind:customErrorMessage={schema.properties[argName].customErrorMessage}
 								properties={schema.properties[argName].properties}
 								nestedRequired={schema.properties[argName].required}
 								bind:itemsType={schema.properties[argName].items}
@@ -131,6 +132,7 @@
 								enum_={schema.properties[argName].enum}
 								format={schema.properties[argName].format}
 								contentEncoding={schema.properties[argName].contentEncoding}
+								customErrorMessage={schema.properties[argName].customErrorMessage}
 								properties={schema.properties[argName].properties}
 								nestedRequired={schema.properties[argName].required}
 								itemsType={schema.properties[argName].items}
diff --git a/frontend/src/lib/components/SchemaModal.svelte b/frontend/src/lib/components/SchemaModal.svelte
index 33cb14fd75..81256973d5 100644
--- a/frontend/src/lib/components/SchemaModal.svelte
+++ b/frontend/src/lib/components/SchemaModal.svelte
@@ -1,5 +1,5 @@
 <script lang="ts" context="module">
-	import type { SchemaProperty, Schema } from '$lib/common'
+	import { type SchemaProperty, type ModalSchemaProperty, modalToSchema } from '$lib/common'
 	import Tab from './common/tabs/Tab.svelte'
 	import TabContent from './common/tabs/TabContent.svelte'
 	import Tabs from './common/tabs/Tabs.svelte'
@@ -8,20 +8,6 @@
 	export const ARG_TYPES = ['integer', 'number', 'string', 'boolean', 'object', 'array'] as const
 	export type ArgType = (typeof ARG_TYPES)[number]
 
-	export interface ModalSchemaProperty {
-		selectedType?: string
-		description: string
-		name: string
-		required: boolean
-		format?: string
-		pattern?: string
-		enum_?: string[]
-		default?: any
-		items?: { type?: 'string' | 'number' }
-		contentEncoding?: 'base64' | 'binary'
-		schema?: Schema
-	}
-
 	export function schemaToModal(
 		schema: SchemaProperty,
 		name: string,
@@ -68,6 +54,7 @@
 	import DrawerContent from './common/drawer/DrawerContent.svelte'
 	import Drawer from './common/drawer/Drawer.svelte'
 	import ArrayTypeNarrowing from './ArrayTypeNarrowing.svelte'
+	import LightweightSchemaForm from './LightweightSchemaForm.svelte'
 
 	export let error = ''
 	export let editing = false
@@ -202,7 +189,10 @@
 						bind:value={property.default}
 						type={property.selectedType}
 						pattern={property.pattern}
+						customErrorMessage={property.customErrorMessage}
 						itemsType={property.items}
+						contentEncoding={property.contentEncoding}
+						format={property.format}
 					/>
 					<Toggle
 						options={{ right: 'Required' }}
@@ -224,6 +214,7 @@
 					<div class="font-semibold text-secondary mb-1">Advanced</div>
 					{#if property.selectedType == 'string'}
 						<StringTypeNarrowing
+							bind:customErrorMessage={property.customErrorMessage}
 							bind:format={property.format}
 							bind:pattern={property.pattern}
 							bind:enum_={property.enum_}
@@ -254,7 +245,18 @@
 				</div>
 			{/if}
 		</div>
+		<div class="font-semibold text-secondary mb-1 pt-4">Preview</div>
+		<LightweightSchemaForm
+			displayType={false}
+			schema={{
+				properties: {
+					[property.name]: modalToSchema(property)
+				},
+				required: property.required ? [property.name] : []
+			}}
+		/>
 		<svelte:fragment slot="actions">
+			<div class="h-10" />
 			<Button
 				color="dark"
 				disabled={!property.name || error != ''}
diff --git a/frontend/src/lib/components/StringTypeNarrowing.svelte b/frontend/src/lib/components/StringTypeNarrowing.svelte
index 553abbb72f..2eecb8ae7a 100644
--- a/frontend/src/lib/components/StringTypeNarrowing.svelte
+++ b/frontend/src/lib/components/StringTypeNarrowing.svelte
@@ -1,12 +1,14 @@
 <script lang="ts">
 	import RadioButton from './RadioButton.svelte'
 	import ResourceTypePicker from './ResourceTypePicker.svelte'
+	import Toggle from './Toggle.svelte'
 	import { Button } from './common'
 
 	export let pattern: string | undefined
 	export let enum_: string[] | undefined
 	export let format: string | undefined
 	export let contentEncoding: 'base64' | 'binary' | undefined
+	export let customErrorMessage: string | undefined
 
 	let kind: 'none' | 'pattern' | 'enum' | 'resource' | 'format' | 'base64' = computeKind()
 	let patternStr: string = pattern ?? ''
@@ -32,6 +34,11 @@
 	$: pattern = patternStr == '' ? undefined : patternStr
 	$: contentEncoding = kind == 'base64' ? 'base64' : undefined
 
+	$: {
+		if (format == 'email') {
+			pattern = '^[\\w-.]+@([\\w-]+\\.)+[\\w-]{2,4}$'
+		}
+	}
 	function add() {
 		enum_ = enum_ ? enum_.concat('') : ['']
 	}
@@ -103,6 +110,22 @@
 				clear
 			</Button>
 		</div>
+		<div class="mt-2 flex gap-2">
+			<Toggle
+				size="xs"
+				options={{ right: 'Custom error message' }}
+				checked={customErrorMessage != undefined && customErrorMessage != ''}
+				on:change={(e) => {
+					if (e.detail) {
+						customErrorMessage = 'Custom error message'
+					} else {
+						customErrorMessage = undefined
+					}
+				}}
+				>Custom error message
+			</Toggle>
+			<input type="text" bind:value={customErrorMessage} />
+		</div>
 	</label>
 {:else if kind == 'enum'}
 	<label for="input" class="mb-2 text-secondary text-xs">
diff --git a/frontend/src/lib/infer.ts b/frontend/src/lib/infer.ts
index 81ab16375b..70edfbaa3b 100644
--- a/frontend/src/lib/infer.ts
+++ b/frontend/src/lib/infer.ts
@@ -123,7 +123,6 @@ function argSigToJsonSchemaType(
 		| { object: { key: string; typ: any }[] },
 	oldS: SchemaProperty
 ): void {
-	console.log(JSON.st)
 	const newS: SchemaProperty = { type: '' }
 	if (t === 'int') {
 		newS.type = 'integer'
diff --git a/frontend/src/lib/utils.ts b/frontend/src/lib/utils.ts
index e5502be6db..64ba48141f 100644
--- a/frontend/src/lib/utils.ts
+++ b/frontend/src/lib/utils.ts
@@ -311,6 +311,7 @@ export function isString(value: any) {
 
 export type InputCat =
 	| 'string'
+	| 'email'
 	| 'number'
 	| 'boolean'
 	| 'list'
@@ -350,6 +351,8 @@ export function setInputCat(
 		return 'yaml'
 	} else if (type == 'string' && contentEncoding == 'base64') {
 		return 'base64'
+	} else if (type == 'string' && format == 'email') {
+		return 'email'
 	} else {
 		return 'string'
 	}