diff --git a/src/selftest/run.ts b/src/selftest/run.ts
index 75ee331..0496163 100644
--- a/src/selftest/run.ts
+++ b/src/selftest/run.ts
@@ -5,24 +5,64 @@ import { createSelfTestContext, type SelfTestCase, type SelfTestResult } from ".
 
 const root = path.resolve(import.meta.dirname, "../..");
 const casesDir = path.join(root, "src/selftest/cases");
-const context = await createSelfTestContext(root);
+
+const args = process.argv.slice(2);
+const listOnly = args.includes("--list");
+const helpRequested = args.some((arg) => arg === "--help" || arg === "-h");
+const requestedCases = args.filter((arg) => arg !== "--list" && arg !== "--help" && arg !== "-h");
+
+function caseName(file: string): string {
+  return file.replace(/\.ts$/u, "");
+}
+
+function normalizeSelector(value: string): string {
+  return caseName(path.basename(value));
+}
 
 try {
   const caseFiles = (await readdir(casesDir))
     .filter((file) => file.endsWith(".ts") && !file.endsWith(".d.ts"))
     .sort();
-  const results: SelfTestResult[] = [];
+  const availableCases = caseFiles.map(caseName);
 
-  for (const file of caseFiles) {
-    const moduleUrl = pathToFileURL(path.join(casesDir, file)).href;
-    const imported = await import(moduleUrl) as { default?: SelfTestCase; selfTest?: SelfTestCase };
-    const selfTest = imported.default ?? imported.selfTest;
-    if (typeof selfTest !== "function") throw new Error(`self-test case ${file} must export default or selfTest function`);
-    const result = await selfTest(context);
-    results.push({ name: result.name ?? file.replace(/\.ts$/u, ""), tests: result.tests ?? [] });
+  if (helpRequested) {
+    console.log(JSON.stringify({ ok: true, usage: "bun run src/selftest/run.ts [--list] [case ...]", availableCases }));
+    process.exit(0);
   }
 
-  console.log(JSON.stringify({ ok: true, cases: results, tests: results.flatMap((result) => result.tests) }));
-} finally {
-  await context.cleanup();
+  if (listOnly) {
+    console.log(JSON.stringify({ ok: true, cases: availableCases }));
+    process.exit(0);
+  }
+
+  const requestedSet = new Set(requestedCases.map(normalizeSelector));
+  const selectedCaseFiles = requestedSet.size === 0
+    ? caseFiles
+    : caseFiles.filter((file) => requestedSet.has(caseName(file)));
+  const missingCases = [...requestedSet].filter((name) => !availableCases.includes(name));
+  if (missingCases.length > 0) {
+    console.error(JSON.stringify({ ok: false, error: "unknown-selftest-case", requestedCases: [...requestedSet], missingCases, availableCases }));
+    process.exit(1);
+  }
+
+  const context = await createSelfTestContext(root);
+  const results: SelfTestResult[] = [];
+
+  try {
+    for (const file of selectedCaseFiles) {
+      const moduleUrl = pathToFileURL(path.join(casesDir, file)).href;
+      const imported = await import(moduleUrl) as { default?: SelfTestCase; selfTest?: SelfTestCase };
+      const selfTest = imported.default ?? imported.selfTest;
+      if (typeof selfTest !== "function") throw new Error(`self-test case ${file} must export default or selfTest function`);
+      const result = await selfTest(context);
+      results.push({ name: result.name ?? caseName(file), tests: result.tests ?? [] });
+    }
+  } finally {
+    await context.cleanup();
+  }
+
+  console.log(JSON.stringify({ ok: true, selectedCases: selectedCaseFiles.map(caseName), cases: results, tests: results.flatMap((result) => result.tests) }));
+} catch (error) {
+  console.error(JSON.stringify({ ok: false, error: error instanceof Error ? error.message : String(error) }));
+  process.exit(1);
 }