[Skills] Foundation: Centralize management logic and feedback rendering (#15952)

packages/cli/src/utils/skillSettings.ts

@@ -0,0 +1,123 @@
+/**
+ * @license
+ * Copyright 2026 Google LLC
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+import {
+  isLoadableSettingScope,
+  type SettingScope,
+  type LoadedSettings,
+} from '../config/settings.js';
+
+export interface ModifiedScope {
+  scope: SettingScope;
+  path: string;
+}
+
+export type SkillActionStatus = 'success' | 'no-op' | 'error';
+
+/**
+ * Metadata representing the result of a skill settings operation.
+ */
+export interface SkillActionResult {
+  status: SkillActionStatus;
+  skillName: string;
+  action: 'enable' | 'disable';
+  /** Scopes where the skill's state was actually changed. */
+  modifiedScopes: ModifiedScope[];
+  /** Scopes where the skill was already in the desired state. */
+  alreadyInStateScopes: ModifiedScope[];
+  /** Error message if status is 'error'. */
+  error?: string;
+}
+
+/**
+ * Enables a skill by removing it from the specified disabled list.
+ */
+export function enableSkill(
+  settings: LoadedSettings,
+  skillName: string,
+  scope: SettingScope,
+): SkillActionResult {
+  if (!isLoadableSettingScope(scope)) {
+    return {
+      status: 'error',
+      skillName,
+      action: 'enable',
+      modifiedScopes: [],
+      alreadyInStateScopes: [],
+      error: `Invalid settings scope: ${scope}`,
+    };
+  }
+
+  const scopePath = settings.forScope(scope).path;
+  const currentScopeDisabled =
+    settings.forScope(scope).settings.skills?.disabled ?? [];
+
+  if (!currentScopeDisabled.includes(skillName)) {
+    return {
+      status: 'no-op',
+      skillName,
+      action: 'enable',
+      modifiedScopes: [],
+      alreadyInStateScopes: [{ scope, path: scopePath }],
+    };
+  }
+
+  const newDisabled = currentScopeDisabled.filter((name) => name !== skillName);
+  settings.setValue(scope, 'skills.disabled', newDisabled);
+
+  return {
+    status: 'success',
+    skillName,
+    action: 'enable',
+    modifiedScopes: [{ scope, path: scopePath }],
+    alreadyInStateScopes: [],
+  };
+}
+
+/**
+ * Disables a skill by adding it to the disabled list in the specified scope.
+ */
+export function disableSkill(
+  settings: LoadedSettings,
+  skillName: string,
+  scope: SettingScope,
+): SkillActionResult {
+  if (!isLoadableSettingScope(scope)) {
+    return {
+      status: 'error',
+      skillName,
+      action: 'disable',
+      modifiedScopes: [],
+      alreadyInStateScopes: [],
+      error: `Invalid settings scope: ${scope}`,
+    };
+  }
+
+  const scopePath = settings.forScope(scope).path;
+  const currentScopeDisabled =
+    settings.forScope(scope).settings.skills?.disabled ?? [];
+
+  if (currentScopeDisabled.includes(skillName)) {
+    return {
+      status: 'no-op',
+      skillName,
+      action: 'disable',
+      modifiedScopes: [],
+      alreadyInStateScopes: [{ scope, path: scopePath }],
+    };
+  }
+
+  const newDisabled = [...currentScopeDisabled, skillName];
+  settings.setValue(scope, 'skills.disabled', newDisabled);
+
+  return {
+    status: 'success',
+    skillName,
+    action: 'disable',
+    modifiedScopes: [{ scope, path: scopePath }],
+    alreadyInStateScopes: [],
+  };
+}

packages/cli/src/utils/skillUtils.ts

@@ -0,0 +1,66 @@
+/**
+ * @license
+ * Copyright 2026 Google LLC
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+import { SettingScope } from '../config/settings.js';
+import type { SkillActionResult } from './skillSettings.js';
+
+/**
+ * Shared logic for building the core skill action message while allowing the
+ * caller to control how each scope and its path are rendered (e.g., bolding or
+ * dimming).
+ *
+ * This function ONLY returns the description of what happened. It is up to the
+ * caller to append any interface-specific guidance (like "Use /skills reload"
+ * or "Restart required").
+ */
+export function renderSkillActionFeedback(
+  result: SkillActionResult,
+  formatScope: (label: string, path: string) => string,
+): string {
+  const { skillName, action, status, error } = result;
+
+  if (status === 'error') {
+    return (
+      error ||
+      `An error occurred while attempting to ${action} skill "${skillName}".`
+    );
+  }
+
+  if (status === 'no-op') {
+    return `Skill "${skillName}" is already ${action === 'enable' ? 'enabled' : 'disabled'}.`;
+  }
+
+  const isEnable = action === 'enable';
+  const actionVerb = isEnable ? 'enabled' : 'disabled';
+  const preposition = isEnable
+    ? 'by removing it from the disabled list in'
+    : 'by adding it to the disabled list in';
+
+  const formatScopeItem = (s: { scope: SettingScope; path: string }) => {
+    const label =
+      s.scope === SettingScope.Workspace ? 'project' : s.scope.toLowerCase();
+    return formatScope(label, s.path);
+  };
+
+  const totalAffectedScopes = [
+    ...result.modifiedScopes,
+    ...result.alreadyInStateScopes,
+  ];
+
+  if (totalAffectedScopes.length === 2) {
+    const s1 = formatScopeItem(totalAffectedScopes[0]);
+    const s2 = formatScopeItem(totalAffectedScopes[1]);
+
+    if (isEnable) {
+      return `Skill "${skillName}" ${actionVerb} ${preposition} ${s1} and ${s2} settings.`;
+    } else {
+      return `Skill "${skillName}" is now disabled in both ${s1} and ${s2} settings.`;
+    }
+  }
+
+  const s = formatScopeItem(totalAffectedScopes[0]);
+  return `Skill "${skillName}" ${actionVerb} ${preposition} ${s} settings.`;
+}