chore: add approved-plan continuity gate skeleton

scripts/approved_plan_continuity_gate.mjs

@@ -0,0 +1,67 @@
+#!/usr/bin/env node
+import fs from 'node:fs';
+
+function parseArgs(argv) {
+  let inputPath = null;
+  let compact = false;
+
+  for (let i = 0; i < argv.length; i += 1) {
+    const arg = argv[i];
+
+    if (arg === '--input') {
+      inputPath = argv[i + 1] ?? null;
+      i += 1;
+      continue;
+    }
+
+    if (arg.startsWith('--input=')) {
+      inputPath = arg.slice('--input='.length);
+      continue;
+    }
+
+    if (arg === '--compact') {
+      compact = true;
+      continue;
+    }
+  }
+
+  return { inputPath, compact };
+}
+
+function readInput(inputPath) {
+  if (!inputPath) {
+    return {
+      ok: false,
+      error: 'missing_required_input',
+    };
+  }
+
+  try {
+    const raw = fs.readFileSync(inputPath, 'utf8');
+    return {
+      ok: true,
+      bytes: Buffer.byteLength(raw, 'utf8'),
+      preview: raw.slice(0, 0),
+    };
+  } catch (error) {
+    return {
+      ok: false,
+      error: error instanceof Error ? error.message : String(error),
+    };
+  }
+}
+
+const { inputPath, compact } = parseArgs(process.argv.slice(2));
+const input = readInput(inputPath);
+
+const response = {
+  ok: true,
+  status: 'placeholder',
+  gate: 'approved_plan_continuity',
+  compact,
+  inputPath,
+  input,
+  verdict: 'not_implemented',
+};
+
+process.stdout.write(`${JSON.stringify(response)}\n`);