diff --git a/frontend/src/lib/components/DynamicInput.svelte b/frontend/src/lib/components/DynamicInput.svelte
index 9f6f3b8261..76395f397f 100644
--- a/frontend/src/lib/components/DynamicInput.svelte
+++ b/frontend/src/lib/components/DynamicInput.svelte
@@ -35,6 +35,9 @@
 		name: string
 		/** Workspace the helper script runs in; defaults to the nav workspace. */
 		workspace?: string
+		/** Reaches the fallback editor too, which is what renders when there is no
+		 * `helperScript` — a caller disabling this argument means all of it. */
+		disabled?: boolean
 	}
 
 	let {
@@ -42,7 +45,8 @@
 		helperScript,
 		format,
 		otherArgs: otherArgs,
-		workspace = undefined
+		workspace = undefined,
+		disabled = false
 	}: Props = $props()
 
 	let [inputType, entrypoint] = $derived(format.includes('-') ? format.split('-', 2) : [format, ''])
@@ -190,7 +194,7 @@
 				items={safeSelectItems(items || [])}
 				placeholder="Select items"
 				noItemsMsg={_items.status === 'loading' ? 'Loading...' : 'No items found'}
-				disabled={_items.status === 'loading'}
+				disabled={disabled || _items.status === 'loading'}
 			/>
 		{:else if inputType === 'dynselect'}
 			<Select
@@ -199,6 +203,7 @@
 				{items}
 				bind:filterText
 				loading={!open && _items.status === 'loading'}
+				{disabled}
 				clearable
 				noItemsMsg={_items.status === 'loading' ? 'Loading...' : 'No items found'}
 			/>
@@ -222,7 +227,7 @@
 		{#await import('$lib/components/JsonEditor.svelte')}
 			<Loader2 class="animate-spin" />
 		{:then Module}
-			<Module.default code={JSON.stringify(value, null, 2)} bind:value />
+			<Module.default code={JSON.stringify(value, null, 2)} {disabled} bind:value />
 		{/await}
 	</div>
 {/if}
diff --git a/frontend/src/lib/components/copilot/chat/RunArgsFormDisplay.svelte b/frontend/src/lib/components/copilot/chat/RunArgsFormDisplay.svelte
index edac4033b8..beab7e6f6b 100644
--- a/frontend/src/lib/components/copilot/chat/RunArgsFormDisplay.svelte
+++ b/frontend/src/lib/components/copilot/chat/RunArgsFormDisplay.svelte
@@ -41,6 +41,12 @@
 	let submitting = $state(false)
 	let cardNode = $state<HTMLDivElement | undefined>()
 
+	// The picker moves while a form sits open, so this is live state, not mount-time. Both
+	// writes the form makes on its own are held off it — the variable a password field
+	// mints on its first keystroke, the entrypoint a `dynselect-` argument runs — because
+	// neither waits for Run, and plan mode promised neither would happen.
+	const planMode = $derived(aiChatManager.planModeActive)
+
 	onMount(() => {
 		void tick().then(() => cardNode?.scrollIntoView({ block: 'nearest' }))
 	})
@@ -119,7 +125,10 @@
 			does not undo it. Everything else waits for the user; keep it that way. -->
 			<SchemaForm
 				bind:schema
-				helperScript={{ source: 'deployed', path: runForm.path, runnable_kind: 'script' }}
+				helperScript={planMode
+					? undefined
+					: { source: 'deployed', path: runForm.path, runnable_kind: 'script' }}
+				disabled={planMode}
 				{workspace}
 				prettifyHeader
 				lightHeader
@@ -153,6 +162,9 @@
 				<span class="font-mono">{runForm.strippedKeys.join(', ')}</span>
 			</p>
 		{/if}
+		{#if planMode}
+			<p class="mt-2 text-2xs text-secondary">{PLAN_MODE_MESSAGES.runFormRefused}</p>
+		{/if}
 	</div>
 
 	<!-- Both buttons rest while a submit is in flight: the ephemeral variables exist by
@@ -163,7 +175,7 @@
 			variant="accent"
 			unifiedSize="sm"
 			startIcon={{ icon: Play }}
-			disabled={!isValid || submitting}
+			disabled={!isValid || submitting || planMode}
 			onClick={run}
 		>
 			Run