restore prior skill when toggling prompt source

Author: charlesvien

packages/ui/src/features/loops/components/LoopSkillFields.tsx

@@ -4,6 +4,7 @@ import { SettingsOptionSelect } from "@posthog/ui/features/settings/SettingsOpti
 import { useHostCapabilities } from "@posthog/ui/shell/useHostCapabilities";
 import { TextArea } from "@radix-ui/themes";
 import { useQuery } from "@tanstack/react-query";
+import { useRef } from "react";
 import type { LoopFormValues } from "../loopFormTypes";
 import type { LoopSkillDraft } from "../loopSkill";
 import { Field } from "./LoopFormPrimitives";
@@ -41,6 +42,7 @@ export function LoopInstructionsFields({
 }) {
   const { localWorkspaces } = useHostCapabilities();
   const trpc = useHostTRPC();
+  const lastSkill = useRef<LoopSkillDraft | null>(values.skill);
   const { data: localSkillData } = useQuery({
     ...trpc.skills.list.queryOptions(),
     enabled: localWorkspaces,
@@ -94,10 +96,17 @@ export function LoopInstructionsFields({
 
   const handleModeChange = (mode: string) => {
     if (mode === "skill") {
-      const first = localSkills[0];
-      if (!first) return;
-      onPatch({ skill: { kind: "local", ...first } });
+      // Restore whatever was picked before the toggle away; defaulting to the
+      // first local skill would silently swap the loop onto an unrelated one.
+      const restored =
+        lastSkill.current ??
+        (localSkills[0] ? { kind: "local" as const, ...localSkills[0] } : null);
+      if (!restored) return;
+      onPatch({ skill: restored });
     } else {
+      if (skill) {
+        lastSkill.current = skill;
+      }
       onPatch({ skill: null });
     }
   };
@@ -106,7 +115,9 @@ export function LoopInstructionsFields({
     if (value === ATTACHED_OPTION_VALUE) return;
     const picked = localSkills.find((local) => local.path === value);
     if (picked) {
-      onPatch({ skill: { kind: "local", ...picked } });
+      const draft: LoopSkillDraft = { kind: "local", ...picked };
+      lastSkill.current = draft;
+      onPatch({ skill: draft });
     }
   };