feat(skills): add optional shell command runner

src/cli/skills.test.ts

@@ -23,6 +23,7 @@ import {
   mergeInstallerExecutionResults,
   runInstallerCommandsWithPolicy,
   noOpSkillInstallerCommandRunner,
+  createShellSkillInstallerCommandRunner,
   runSkillInstallAction,
 } from './skills.js';
 import type { Skill } from '../skills/index.js';
@@ -376,6 +377,33 @@ describe('skills CLI helpers', () => {
     expect(runner.run).toHaveBeenCalledWith(['brew install jq']);
   });
 
+  it('shell command runner reports succeeded command status', () => {
+    const runner = createShellSkillInstallerCommandRunner();
+
+    const results = runner.run(['node -e "process.exit(0)"']);
+
+    expect(results).toEqual([
+      {
+        command: 'node -e "process.exit(0)"',
+        status: 'succeeded',
+      },
+    ]);
+  });
+
+  it('shell command runner reports failed command with exit code reason', () => {
+    const runner = createShellSkillInstallerCommandRunner();
+
+    const results = runner.run(['node -e "process.exit(7)"']);
+
+    expect(results).toEqual([
+      {
+        command: 'node -e "process.exit(7)"',
+        status: 'failed',
+        reason: 'exit_code_7',
+      },
+    ]);
+  });
+
   it('maps runner command results into structured per-step statuses', () => {
     const attempted = [
       { installer_type: 'brew', command: 'brew install jq' },

src/cli/skills.ts

@@ -1,6 +1,7 @@
 import type { Command } from 'commander';
 import { resolve } from 'path';
 import { homedir } from 'os';
+import { spawnSync } from 'child_process';
 import type { Skill } from '../skills/index.js';
 import { loadAllSkills, SkillInstaller, buildInstallerPlan, loadSkill } from '../skills/index.js';
 import { loadConfigSafe } from './shared.js';
@@ -78,6 +79,57 @@ export const noOpSkillInstallerCommandRunner: SkillInstallerCommandRunner = {
   },
 };
 
+export function createShellSkillInstallerCommandRunner(): SkillInstallerCommandRunner {
+  return {
+    run(commands: string[]): SkillInstallerCommandRunResult[] {
+      return commands.map((command) => {
+        const result = spawnSync(command, {
+          shell: true,
+          stdio: 'pipe',
+          encoding: 'utf-8',
+        });
+
+        if (result.error) {
+          return {
+            command,
+            status: 'failed',
+            reason: `spawn_error:${result.error.message}`,
+          };
+        }
+
+        if (result.status === 0) {
+          return {
+            command,
+            status: 'succeeded',
+          };
+        }
+
+        if (result.status !== null) {
+          return {
+            command,
+            status: 'failed',
+            reason: `exit_code_${result.status}`,
+          };
+        }
+
+        if (result.signal) {
+          return {
+            command,
+            status: 'failed',
+            reason: `signal_${result.signal}`,
+          };
+        }
+
+        return {
+          command,
+          status: 'failed',
+          reason: 'unknown_failure',
+        };
+      });
+    },
+  };
+}
+
 export function toInstallerExecutionStepEnvelopes(
   steps: Array<{ installerType: string; command: string }>,
   policy: SkillInstallerExecutionPolicy,