diff --git a/frontend/src/lib/components/JsonInputs.svelte b/frontend/src/lib/components/JsonInputs.svelte
index 2f4b04f8e4..546ab36069 100644
--- a/frontend/src/lib/components/JsonInputs.svelte
+++ b/frontend/src/lib/components/JsonInputs.svelte
@@ -13,13 +13,18 @@
 		 * payload nobody has typed into tracks the schema instead of going stale. The first edit
 		 * hands the buffer to the user and later changes stop overwriting it. */
 		initialCode?: string
+		/** Show the payload without taking edits. For a caller that must keep this editor
+		 * mounted while refusing writes: swapping it for the fields instead would mount the
+		 * widgets, and a `password` field mints a variable from whatever literal it opens on. */
+		readOnly?: boolean
 	}
 
 	let {
 		updateOnBlur = true,
 		placeholder = 'Write a JSON payload. The input schema will be inferred.<br/><br/>Example:<br/><br/>{<br/>&nbsp;&nbsp;"foo": "12"<br/>}',
 		selected = false,
-		initialCode = ''
+		initialCode = '',
+		readOnly = false
 	}: Props = $props()
 
 	let pendingJson = $state(untrack(() => initialCode))
@@ -130,6 +135,7 @@
 			bind:code={pendingJson}
 			lang="json"
 			class="h-full json-inputs-editor"
+			{readOnly}
 			{placeholder}
 		/>
 	</div>
diff --git a/frontend/src/lib/components/RunForm.svelte b/frontend/src/lib/components/RunForm.svelte
index cede84f394..c01f7598ca 100644
--- a/frontend/src/lib/components/RunForm.svelte
+++ b/frontend/src/lib/components/RunForm.svelte
@@ -135,10 +135,13 @@
 			  }
 			| undefined
 		/** Set to refuse every write this form can make, and to say so when a run is
-		 * attempted. No edits, no dynamic-select helper, no JSON, and no run — `run()` mints
-		 * the `password` arguments it is about to send, so refusing in `runAction` is already
-		 * too late. For a form standing in for a chat card under plan mode, which promised
-		 * none of it. */
+		 * attempted: the fields are disabled, the dynamic-select helper is not wired, the JSON
+		 * editor is read-only, and `run()` refuses before it mints the `password` arguments it
+		 * would send — so a caller cannot gate this in `runAction`, which comes after that
+		 * mint. For a form standing in for a chat card under plan mode, which promised none of
+		 * it. The caller must also leave this form on the side it is showing: swapping fields
+		 * for JSON or back mounts a `password` widget, which mints from the literal it opens
+		 * on regardless of being disabled. */
 		runRefusal?: string
 		runAction: (
 			scheduledForStr: string | undefined,
@@ -349,6 +352,7 @@
 			>
 				<JsonInputs
 					bind:this={jsonEditor}
+					readOnly={argsReadonly}
 					on:select={(e) => {
 						// The other way into the arguments, and the one disabling the fields misses.
 						if (argsReadonly) return
diff --git a/frontend/src/lib/components/details/FlowDetail.svelte b/frontend/src/lib/components/details/FlowDetail.svelte
index 8612f871f9..b9ca597f6d 100644
--- a/frontend/src/lib/components/details/FlowDetail.svelte
+++ b/frontend/src/lib/components/details/FlowDetail.svelte
@@ -865,6 +865,10 @@
 											{inputSelected}
 										/>
 
+										<!-- Not offered while the form refuses writes: each side of this
+										     toggle mounts what the other unmounts, and a `password` field
+										     mints a variable from the literal it opens on. The form stays on
+										     whichever side it is already showing, read-only. -->
 										{#if hasSchema && !pendingRun?.planModeActive}
 											<Toggle
 												bind:checked={jsonView}
@@ -921,7 +925,7 @@
 									bind:args
 									schedulable={!pendingRun}
 									bind:this={runForm}
-									jsonView={jsonView && !pendingRun?.planModeActive}
+									{jsonView}
 									actions={promptForAi ? undefined : aiAssistant}
 								/>
 							</div>
diff --git a/frontend/src/lib/components/details/ScriptDetail.svelte b/frontend/src/lib/components/details/ScriptDetail.svelte
index acb61567f8..6d463434eb 100644
--- a/frontend/src/lib/components/details/ScriptDetail.svelte
+++ b/frontend/src/lib/components/details/ScriptDetail.svelte
@@ -1059,6 +1059,10 @@
 										}}
 										{inputSelected}
 									/>
+									<!-- Not offered while the form refuses writes: each side of this toggle
+									     mounts what the other unmounts, and a `password` field mints a
+									     variable from the literal it opens on. The form stays on whichever
+									     side it is already showing, read-only. -->
 									{#if hasSchema && !pendingRun?.planModeActive}
 										<Toggle
 											bind:checked={jsonView}
@@ -1135,7 +1139,7 @@
 								bind:args
 								schedulable={!pendingRun}
 								bind:this={runForm}
-								jsonView={jsonView && !pendingRun?.planModeActive}
+								{jsonView}
 								actions={promptForAi ? undefined : aiAssistant}
 							/>
 						</div>