chore: import upstream snapshot with attribution

apps/sim/lib/mothership/skills.ts

@@ -0,0 +1,67 @@
+import { db, skill } from '@sim/db'
+import { createLogger } from '@sim/logger'
+import { eq } from 'drizzle-orm'
+import type { ToolSchema } from '@/lib/copilot/chat/payload'
+
+const logger = createLogger('MothershipUserSkills')
+
+export const LOAD_USER_SKILL_TOOL_NAME = 'load_user_skill'
+
+/**
+ * Build the single load_user_skill tool that exposes all workspace
+ * user-created skills to the mothership and its subagents.
+ *
+ * User skills live in the `skill` table (builtins are code-only and are treated
+ * as defaults, so they are excluded here). The tool is a non-deferred,
+ * sim-executed request-local tool: when the model calls it, Go forwards the
+ * call and sim resolves the content via resolveSkillContent (see tools/index.ts).
+ * It is available to all users — there is no super-admin gate, unlike the curated
+ * mothership_settings tools.
+ *
+ * Embedded copilot/internal skills are not handled here: those are autoloaded
+ * into each agent's system prompt on the Go side and never sent as loadable.
+ */
+export async function buildUserSkillTool(workspaceId: string): Promise<ToolSchema | null> {
+  if (!workspaceId) return null
+
+  let rows: { name: string; description: string }[]
+  try {
+    rows = await db
+      .select({ name: skill.name, description: skill.description })
+      .from(skill)
+      .where(eq(skill.workspaceId, workspaceId))
+  } catch (error) {
+    logger.error('Failed to load workspace skills for load_user_skill tool', { error, workspaceId })
+    return null
+  }
+
+  if (rows.length === 0) return null
+
+  const skillNames = rows.map((r) => r.name)
+  const catalog = rows.map((r) => `- ${r.name}: ${r.description}`).join('\n')
+
+  return {
+    name: LOAD_USER_SKILL_TOOL_NAME,
+    description: `Load a user-created skill's full instructions. You MUST call this before following a skill: the list below only tells you which skills exist and when each applies — it is NOT the instructions. To use a skill, call load_user_skill with its exact name and follow the content it returns; never act on a skill's name or description alone. Available skills:\n${catalog}`,
+    input_schema: {
+      type: 'object',
+      properties: {
+        skill_name: {
+          type: 'string',
+          description: 'Exact name of the user skill to load.',
+          enum: skillNames,
+        },
+      },
+      required: ['skill_name'],
+      additionalProperties: false,
+    },
+    // Do NOT set executeLocally: skill content is resolved on the sim backend
+    // (DB), so Go must dispatch this with executor "sim". executeLocally maps to
+    // ClientExecutable, which routes the call to the browser client (no handler)
+    // and the load hangs. mothershipToolKind 'skill' is enough for sim routing.
+    params: {
+      mothershipToolKind: 'skill',
+      mothershipToolName: LOAD_USER_SKILL_TOOL_NAME,
+    },
+  }
+}