feat(check): add --json flag to check command

src/cli.test.ts

@@ -1,7 +1,8 @@
 import { describe, it, expect } from 'vitest';
-import { readFileSync } from 'fs';
+import { readFileSync, mkdtempSync } from 'fs';
 import { join } from 'path';
-import { runCliOutput, stripLogo, hasLogo } from './test-utils.ts';
+import { tmpdir } from 'os';
+import { runCli, runCliOutput, stripLogo, hasLogo } from './test-utils.ts';
 
 describe('skills CLI', () => {
   describe('--help', () => {
@@ -14,6 +15,7 @@ describe('skills CLI', () => {
       expect(output).toContain('check');
       expect(output).toContain('update');
       expect(output).toContain('Add Options:');
+      expect(output).toContain('Check Options:');
       expect(output).toContain('-g, --global');
       expect(output).toContain('-a, --agent');
       expect(output).toContain('-s, --skill');
@@ -67,6 +69,28 @@ describe('skills CLI', () => {
     });
   });
 
+  describe('check --json', () => {
+    it('should output valid JSON with no skills', () => {
+      const tempState = mkdtempSync(join(tmpdir(), 'skills-check-test-'));
+      const result = runCli(['check', '--json'], undefined, { XDG_STATE_HOME: tempState });
+      const parsed = JSON.parse(result.stdout.trim());
+      expect(parsed).toEqual([]);
+    });
+
+    it('should output an array', () => {
+      const tempState = mkdtempSync(join(tmpdir(), 'skills-check-test-'));
+      const result = runCli(['check', '--json'], undefined, { XDG_STATE_HOME: tempState });
+      const parsed = JSON.parse(result.stdout.trim());
+      expect(Array.isArray(parsed)).toBe(true);
+    });
+
+    it('should not contain ANSI codes', () => {
+      const tempState = mkdtempSync(join(tmpdir(), 'skills-check-test-'));
+      const result = runCli(['check', '--json'], undefined, { XDG_STATE_HOME: tempState });
+      expect(result.stdout).not.toMatch(/\x1b\[/);
+    });
+  });
+
   describe('logo display', () => {
     it('should not display logo for list command', () => {
       const output = runCliOutput(['list']);

src/cli.ts

@@ -150,6 +150,9 @@ ${BOLD}List Options:${RESET}
   -a, --agent <agents>   Filter by specific agents
   --json                 Output as JSON (machine-readable, no ANSI codes)
 
+${BOLD}Check Options:${RESET}
+  --json                 Output as JSON (machine-readable, no ANSI codes)
+
 ${BOLD}Options:${RESET}
   --help, -h        Show this help message
   --version, -v     Show version number
@@ -169,6 +172,7 @@ ${BOLD}Examples:${RESET}
   ${DIM}$${RESET} skills find                          ${DIM}# interactive search${RESET}
   ${DIM}$${RESET} skills find typescript               ${DIM}# search by keyword${RESET}
   ${DIM}$${RESET} skills check
+  ${DIM}$${RESET} skills check --json                     ${DIM}# JSON output${RESET}
   ${DIM}$${RESET} skills update
   ${DIM}$${RESET} skills experimental_install            ${DIM}# restore from skills-lock.json${RESET}
   ${DIM}$${RESET} skills init my-skill
@@ -397,13 +401,21 @@ function printSkippedSkills(skipped: SkippedSkill[]): void {
 }
 
 async function runCheck(args: string[] = []): Promise<void> {
-  console.log(`${TEXT}Checking for skill updates...${RESET}`);
-  console.log();
+  const json = args.includes('--json');
+
+  if (!json) {
+    console.log(`${TEXT}Checking for skill updates...${RESET}`);
+    console.log();
+  }
 
   const lock = readSkillLock();
   const skillNames = Object.keys(lock.skills);
 
   if (skillNames.length === 0) {
+    if (json) {
+      console.log(JSON.stringify([], null, 2));
+      return;
+    }
     console.log(`${DIM}No skills tracked in lock file.${RESET}`);
     console.log(`${DIM}Install skills with${RESET} ${TEXT}npx skills add <package>${RESET}`);
     return;
@@ -433,12 +445,18 @@ async function runCheck(args: string[] = []): Promise<void> {
 
   const totalSkills = skillNames.length - skipped.length;
   if (totalSkills === 0) {
+    if (json) {
+      console.log(JSON.stringify([], null, 2));
+      return;
+    }
     console.log(`${DIM}No GitHub skills to check.${RESET}`);
     printSkippedSkills(skipped);
     return;
   }
 
-  console.log(`${DIM}Checking ${totalSkills} skill(s) for updates...${RESET}`);
+  if (!json) {
+    console.log(`${DIM}Checking ${totalSkills} skill(s) for updates...${RESET}`);
+  }
 
   const updates: Array<{ name: string; source: string }> = [];
   const errors: Array<{ name: string; source: string; error: string }> = [];
@@ -467,6 +485,17 @@ async function runCheck(args: string[] = []): Promise<void> {
     }
   }
 
+  if (json) {
+    console.log(
+      JSON.stringify(
+        updates.map((u) => ({ name: u.name, source: u.source })),
+        null,
+        2
+      )
+    );
+    return;
+  }
+
   console.log();
 
   if (updates.length === 0) {