fix(skills): harden slash skill activation across chat channels (#3466)

* support slash skill activation

* format slash skill activation

* Preserve slash skill activation with uploads

* Address slash skill review feedback

* Address slash skill follow-up review

* Fix lazy slash skill storage resolution

* Keep slash skill activation out of system prompt

* Address slash skill review issues

* fix: harden slash skill command handling

* feat(frontend): add slash skill autocomplete

* fix: address slash skill review feedback

* fix: preserve slash skill text for IM uploads

frontend/tests/e2e/utils/mock-api.ts

@@ -35,11 +35,41 @@ export type MockAgent = {
   system_prompt?: string;
 };
 
+export type MockSkill = {
+  name: string;
+  description: string;
+  category?: string;
+  license?: string | null;
+  enabled?: boolean;
+};
+
 export type MockAPIOptions = {
   threads?: MockThread[];
   agents?: MockAgent[];
+  skills?: MockSkill[];
 };
 
+const DEFAULT_SKILLS: MockSkill[] = [
+  {
+    name: "data-analysis",
+    description: "Analyze structured data and produce charts.",
+    category: "public",
+    enabled: true,
+  },
+  {
+    name: "frontend-design",
+    description: "Create polished frontend interfaces.",
+    category: "public",
+    enabled: true,
+  },
+  {
+    name: "disabled-skill",
+    description: "Hidden from slash autocomplete.",
+    category: "public",
+    enabled: false,
+  },
+];
+
 // ---------------------------------------------------------------------------
 // mockLangGraphAPI
 // ---------------------------------------------------------------------------
@@ -52,6 +82,7 @@ export type MockAPIOptions = {
 export function mockLangGraphAPI(page: Page, options?: MockAPIOptions) {
   const threads = options?.threads ?? [];
   const agents = options?.agents ?? [];
+  const skills = options?.skills ?? DEFAULT_SKILLS;
 
   // Thread search — sidebar thread list & chats list page
   void page.route("**/api/langgraph/threads/search", (route) => {
@@ -259,6 +290,18 @@ export function mockLangGraphAPI(page: Page, options?: MockAPIOptions) {
     return route.fallback();
   });
 
+  // Skills list — settings page and slash autocomplete
+  void page.route("**/api/skills", (route) => {
+    if (route.request().method() === "GET") {
+      return route.fulfill({
+        status: 200,
+        contentType: "application/json",
+        body: JSON.stringify({ skills }),
+      });
+    }
+    return route.fallback();
+  });
+
   // Follow-up suggestions — input box auto-suggest after AI response
   void page.route("**/api/threads/*/suggestions", (route) => {
     if (route.request().method() === "POST") {