feat(skills): validate manifest permissions

src/skills/loader.ts

@@ -53,6 +53,84 @@ function hasValidInstallers(manifest: unknown): boolean {
   });
 }
 
+function isNumberArray(value: unknown): value is number[] {
+  return Array.isArray(value) && value.every((item) => typeof item === 'number' && Number.isFinite(item));
+}
+
+function hasValidPermissions(manifest: unknown): boolean {
+  if (!manifest || typeof manifest !== 'object') {
+    return false;
+  }
+
+  const candidate = manifest as { permissions?: unknown };
+  if (candidate.permissions === undefined) {
+    return true;
+  }
+
+  if (!candidate.permissions || typeof candidate.permissions !== 'object') {
+    return false;
+  }
+
+  const perms = candidate.permissions as {
+    tool_groups?: unknown;
+    tools?: unknown;
+    fs?: unknown;
+    net?: unknown;
+    secrets?: unknown;
+    execution_environment?: unknown;
+  };
+
+  if (perms.tool_groups !== undefined && !isStringArray(perms.tool_groups)) {
+    return false;
+  }
+  if (perms.tools !== undefined && !isStringArray(perms.tools)) {
+    return false;
+  }
+
+  if (perms.fs !== undefined) {
+    if (!perms.fs || typeof perms.fs !== 'object') {
+      return false;
+    }
+    const fsPerms = perms.fs as { read?: unknown; write?: unknown };
+    if (fsPerms.read !== undefined && !isStringArray(fsPerms.read)) {
+      return false;
+    }
+    if (fsPerms.write !== undefined && !isStringArray(fsPerms.write)) {
+      return false;
+    }
+  }
+
+  if (perms.net !== undefined) {
+    if (!Array.isArray(perms.net)) {
+      return false;
+    }
+    for (const entry of perms.net) {
+      if (!entry || typeof entry !== 'object') {
+        return false;
+      }
+      const e = entry as { host?: unknown; ports?: unknown };
+      if (typeof e.host !== 'string' || e.host.trim().length === 0) {
+        return false;
+      }
+      if (e.ports !== undefined && !isNumberArray(e.ports)) {
+        return false;
+      }
+    }
+  }
+
+  if (perms.secrets !== undefined && !isStringArray(perms.secrets)) {
+    return false;
+  }
+
+  if (perms.execution_environment !== undefined) {
+    if (perms.execution_environment !== 'sandbox' && perms.execution_environment !== 'host') {
+      return false;
+    }
+  }
+
+  return true;
+}
+
 /**
  * Check whether a skill's system requirements are met.
  *
@@ -136,6 +214,10 @@ export function loadSkill(directory: string, tier: SkillTier): Skill | null {
         console.warn(`Skill manifest at ${manifestPath} has invalid installers specification`);
         return null;
       }
+      if (!hasValidPermissions(raw)) {
+        console.warn(`Skill manifest at ${manifestPath} has invalid permissions specification`);
+        return null;
+      }
 
       manifest = {
         ...raw,