Add smart ACK provider for WeChat MP replies

Replace fixed ackText with a rule-based AckProvider that picks
response templates by message type and intent (translate, summary,
rewrite, poster, ppt, mindmap, code, search, schedule). Pure sync,
zero I/O, auto-falls back to config.ackText on any error.

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

mindspace-config.mjs

@@ -0,0 +1,96 @@
+const PUBLIC_PAGE_LIMIT_KEY = 'public_page_limit';
+
+function asPositiveInteger(value, fallback) {
+  const parsed = Number(value);
+  if (!Number.isFinite(parsed) || parsed < 1) return fallback;
+  return Math.floor(parsed);
+}
+
+async function ensureConfigTable(pool) {
+  await pool.query(`
+    CREATE TABLE IF NOT EXISTS mindspace_config (
+      \`key\` VARCHAR(64) PRIMARY KEY,
+      value TEXT NOT NULL,
+      description VARCHAR(255) NULL,
+      updated_at BIGINT NOT NULL
+    ) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_unicode_ci
+  `);
+}
+
+export function defaultMindSpaceConfig(env = process.env) {
+  return {
+    publicPageLimit: asPositiveInteger(env.MINDSPACE_FREE_PUBLIC_PAGE_LIMIT ?? 5, 5),
+  };
+}
+
+async function readConfigRows(pool) {
+  const [rows] = await pool.query(
+    'SELECT `key`, value FROM mindspace_config',
+  );
+  return rows;
+}
+
+export async function ensureMindSpaceConfig(pool, { env = process.env, seedDefault = true } = {}) {
+  await ensureConfigTable(pool);
+  if (!seedDefault) return;
+  const [rows] = await pool.query('SELECT COUNT(*) AS count FROM mindspace_config');
+  if (Number(rows[0]?.count ?? 0) > 0) return;
+
+  const now = Date.now();
+  const defaults = defaultMindSpaceConfig(env);
+  await pool.query(
+    `INSERT INTO mindspace_config (\`key\`, value, description, updated_at)
+     VALUES (?, ?, ?, ?)`,
+    [PUBLIC_PAGE_LIMIT_KEY, String(defaults.publicPageLimit), '公开页面数量上限', now],
+  );
+}
+
+export async function loadMindSpaceConfig(pool, { env = process.env } = {}) {
+  const config = defaultMindSpaceConfig(env);
+  try {
+    const rows = await readConfigRows(pool);
+    for (const row of rows) {
+      if (row.key === PUBLIC_PAGE_LIMIT_KEY) {
+        config.publicPageLimit = asPositiveInteger(row.value, config.publicPageLimit);
+      }
+    }
+  } catch (error) {
+    if (error?.code === 'ER_NO_SUCH_TABLE') return config;
+    throw error;
+  }
+  return config;
+}
+
+export async function updateMindSpaceConfig(pool, patch, { env = process.env } = {}) {
+  await ensureConfigTable(pool);
+  const updates = [];
+  if (patch?.publicPageLimit !== undefined) {
+    const publicPageLimit = asPositiveInteger(patch.publicPageLimit, null);
+    if (!publicPageLimit) {
+      throw Object.assign(new Error('公开页面数量上限必须是大于 0 的整数'), {
+        code: 'invalid_mindspace_config',
+      });
+    }
+    updates.push([PUBLIC_PAGE_LIMIT_KEY, String(publicPageLimit), '公开页面数量上限']);
+  }
+
+  if (updates.length === 0) return loadMindSpaceConfig(pool, { env });
+
+  const now = Date.now();
+  for (const [key, value, description] of updates) {
+    await pool.query(
+      `INSERT INTO mindspace_config (\`key\`, value, description, updated_at)
+       VALUES (?, ?, ?, ?)
+       ON DUPLICATE KEY UPDATE
+         value = VALUES(value),
+         description = VALUES(description),
+         updated_at = VALUES(updated_at)`,
+      [key, value, description, now],
+    );
+  }
+  return loadMindSpaceConfig(pool, { env });
+}
+
+export const mindspaceConfigInternals = {
+  PUBLIC_PAGE_LIMIT_KEY,
+};