fix(yara): match skill install paths case-insensitively in the Bash hook

src/agent/__tests__/skill-case-scan.test.ts

@@ -0,0 +1,54 @@
+import fs from 'node:fs';
+import os from 'node:os';
+import path from 'node:path';
+import { scan } from '@posthog/warlock';
+import { createPostToolUseYaraHooks } from '@agent/yara-hooks';
+
+vi.mock('@utils/debug');
+vi.mock('@utils/analytics');
+
+const poisoned = {
+  matched: true as const,
+  matches: [
+    {
+      rule: 'prompt_injection_instruction_override',
+      metadata: { severity: 'critical' as const, scan_context: 'input' },
+      matchedStrings: [],
+    },
+  ],
+};
+
+it('scans uppercase text files in a skill the agent installed with Bash', async () => {
+  const cwd = fs.mkdtempSync(path.join(os.tmpdir(), 'wizard-case-scan-'));
+  const skillDir = '.claude/skills/nextjs';
+  fs.mkdirSync(path.join(cwd, skillDir), { recursive: true });
+  fs.writeFileSync(path.join(cwd, skillDir, 'SKILL.md'), '# Loadable skill');
+  fs.writeFileSync(path.join(cwd, skillDir, 'PAYLOAD.TXT'), 'poisoned text');
+  vi.mocked(scan).mockImplementation((content) =>
+    Promise.resolve(
+      content.includes('poisoned text') ? poisoned : { matched: false },
+    ),
+  );
+  const onTerminate = vi.fn();
+  const hook = createPostToolUseYaraHooks(undefined, onTerminate)[2].hooks[0];
+  try {
+    const result = await hook(
+      {
+        session_id: 's1',
+        transcript_path: '/tmp/t',
+        cwd,
+        tool_name: 'Bash',
+        tool_input: {
+          command: `mkdir -p ${skillDir} && curl -sL 'https://github.com/PostHog/context-mill/releases/download/v1/nextjs.tar.gz' | tar xzf - -C ${skillDir}`,
+        },
+      },
+      't1',
+      { signal: new AbortController().signal },
+    );
+    expect(result.stopReason).toContain('Poisoned skill');
+    expect(onTerminate).toHaveBeenCalledTimes(1);
+  } finally {
+    fs.rmSync(cwd, { recursive: true, force: true });
+    vi.mocked(scan).mockReset();
+  }
+});

src/agent/yara-hooks.ts

@@ -1154,6 +1154,7 @@ async function scanSkillFiles(
   const files = await fg('**/*.{md,txt,yaml,yml,json,js,ts,py,rb,sh}', {
     cwd: absoluteDir,
     absolute: true,
+    caseSensitiveMatch: false,
   });
 
   if (files.length === 0) {