fix: Push3 evolution: selection loop orchestrator (#546)

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

tools/push3-evolution/mutate-cli.ts

@@ -0,0 +1,57 @@
+/**
+ * mutate-cli.ts — CLI wrapper for Push3 mutation operators.
+ *
+ * Commands:
+ *   mutate    <push3file> <rate>           Apply `rate` random mutations.
+ *   crossover <push3file1> <push3file2>    Single-point crossover of two programs.
+ *
+ * Outputs the resulting Push3 program text to stdout.
+ * Exits 1 on invalid input or mutation failure.
+ */
+
+import { readFileSync } from 'fs';
+import { parse } from '../push3-transpiler/src/parser';
+import { mutate, crossover, serialize } from './mutate';
+
+function loadProgram(filePath: string) {
+  const src = readFileSync(filePath, 'utf8');
+  return parse(src);
+}
+
+const [, , cmd, ...args] = process.argv;
+
+switch (cmd) {
+  case 'mutate': {
+    const [file, rateStr] = args;
+    if (!file || !rateStr) {
+      process.stderr.write('Usage: mutate-cli mutate <push3file> <rate>\n');
+      process.exit(1);
+    }
+    const rate = parseInt(rateStr, 10);
+    if (isNaN(rate) || rate < 0) {
+      process.stderr.write(`Invalid rate: ${rateStr}\n`);
+      process.exit(1);
+    }
+    const program = loadProgram(file);
+    const mutated = mutate(program, rate);
+    process.stdout.write(serialize(mutated) + '\n');
+    break;
+  }
+
+  case 'crossover': {
+    const [file1, file2] = args;
+    if (!file1 || !file2) {
+      process.stderr.write('Usage: mutate-cli crossover <push3file1> <push3file2>\n');
+      process.exit(1);
+    }
+    const a = loadProgram(file1);
+    const b = loadProgram(file2);
+    const crossed = crossover(a, b);
+    process.stdout.write(serialize(crossed) + '\n');
+    break;
+  }
+
+  default:
+    process.stderr.write(`Unknown command: ${cmd}\nCommands: mutate, crossover\n`);
+    process.exit(1);
+}