feat: add semantic WeChat session actions

wechat/intent/classifier.mjs

@@ -6,6 +6,7 @@ import {
   isTopicResetText,
   wantsDocxDownload,
 } from './patterns.mjs';
+import { WECHAT_SESSION_ACTION } from './session-action.mjs';
 
 /**
  * @typedef {object} WechatPageGenerateIntent
@@ -15,6 +16,7 @@ import {
  *
  * @typedef {object} WechatSessionResetIntent
  * @property {'session.reset'} kind
+ * @property {string} sessionAction
  *
  * @typedef {object} WechatStatusProbeIntent
  * @property {'status.probe'} kind
@@ -46,7 +48,9 @@ export function classifyWechatIntent(intent) {
   const text = String(intent?.agentText ?? intent?.displayText ?? '').trim();
 
   if (msgType === 'text' || msgType === 'voice') {
-    if (isTopicResetText(text)) return { kind: 'session.reset' };
+    if (isTopicResetText(text)) {
+      return { kind: 'session.reset', sessionAction: WECHAT_SESSION_ACTION.RESET };
+    }
     if (STATUS_PROBE_PATTERN.test(text)) return { kind: 'status.probe' };
     if (GREETING_PATTERN.test(text.replace(/[!！。.\s]+$/g, ''))) return { kind: 'greeting' };
     if (CONNECTIVITY_TEST_PATTERN.test(text.replace(/[!！。.\s]+$/g, ''))) {

wechat/intent/session-action.mjs

@@ -0,0 +1,95 @@
+/** Session actions are broader than one fixed reset phrase. */
+export const WECHAT_SESSION_ACTION = Object.freeze({
+  CONTINUE: 'continue',
+  RESET: 'reset',
+  IGNORE_PREVIOUS: 'ignore_previous',
+  UNCLEAR: 'unclear',
+});
+
+const RESET_VERBS = /(?:换|开|新建|开启|开始|另起|重新|从头|清空|作废)/u;
+const RESET_TARGETS = /(?:新?会话|对话|聊天|上下文|话题|主题)/u;
+const CONTEXT_REFERENCES = /(?:之前|刚才|前面|上面|当前|这个|刚刚)/u;
+const IGNORE_VERBS = /(?:忽略|不要管|别管|不参考|不要参考|不用参考|忘掉|忘记)/u;
+const CONTINUE_VERBS = /(?:继续|接着|还是|回到|沿着)/u;
+const SESSION_SEMANTIC_HINT = /(?:换个思路|另一个话题|不同话题|重置|清除|忘记刚才|刚才.*不要|从现在开始)/u;
+
+function normalizeText(text) {
+  return String(text ?? '')
+    .trim()
+    .replace(/[\u200b-\u200d\ufeff]/g, '')
+    .replace(/[\s，。！？、；：“”‘’（）()【】\[\]{}]+/gu, '');
+}
+
+function classifyByMeaning(text) {
+  const normalized = normalizeText(text);
+  if (!normalized) return { action: WECHAT_SESSION_ACTION.UNCLEAR, confidence: 0 };
+
+  const hasTarget = RESET_TARGETS.test(normalized);
+  const hasContext = CONTEXT_REFERENCES.test(normalized);
+  const hasResetVerb = RESET_VERBS.test(normalized);
+  const hasIgnoreVerb = IGNORE_VERBS.test(normalized);
+  const hasContinueVerb = CONTINUE_VERBS.test(normalized);
+
+  if (hasContinueVerb && hasTarget && !hasResetVerb) {
+    return { action: WECHAT_SESSION_ACTION.CONTINUE, confidence: 0.94, source: 'semantic_rules' };
+  }
+  if (hasIgnoreVerb && (hasContext || hasTarget) && !/(?:新|重新|另起|开启|开始)/u.test(normalized)) {
+    return { action: WECHAT_SESSION_ACTION.IGNORE_PREVIOUS, confidence: 0.9, source: 'semantic_rules' };
+  }
+  if ((hasResetVerb && hasTarget) || /(?:重新开始|从头来|重来一次|另开一个)/u.test(normalized)) {
+    return { action: WECHAT_SESSION_ACTION.RESET, confidence: 0.98, source: 'semantic_rules' };
+  }
+  return { action: WECHAT_SESSION_ACTION.UNCLEAR, confidence: 0.35, source: 'fallback' };
+}
+
+function normalizeSemanticResult(result) {
+  if (!result) return null;
+  const raw = String(result.action ?? result.intent ?? result.label ?? '').trim().toLowerCase();
+  const aliases = {
+    'session.reset': WECHAT_SESSION_ACTION.RESET,
+    reset: WECHAT_SESSION_ACTION.RESET,
+    new_session: WECHAT_SESSION_ACTION.RESET,
+    continue: WECHAT_SESSION_ACTION.CONTINUE,
+    reuse: WECHAT_SESSION_ACTION.CONTINUE,
+    ignore_previous: WECHAT_SESSION_ACTION.IGNORE_PREVIOUS,
+    ignore: WECHAT_SESSION_ACTION.IGNORE_PREVIOUS,
+    unclear: WECHAT_SESSION_ACTION.UNCLEAR,
+  };
+  const action = aliases[raw];
+  if (!action) return null;
+  return {
+    action,
+    confidence: Number.isFinite(Number(result.confidence)) ? Number(result.confidence) : 0.7,
+    source: 'semantic_model',
+    reason: String(result.reason ?? '').trim() || null,
+  };
+}
+
+/**
+ * Resolve a session action. A channel may inject a small semantic model for
+ * ambiguous phrases; the meaning-based fallback keeps this path safe when the
+ * model is unavailable or times out.
+ */
+export async function resolveWechatSessionAction(text, { semanticClassifier = null, logger = console } = {}) {
+  const deterministic = classifyByMeaning(text);
+  if (deterministic.action !== WECHAT_SESSION_ACTION.UNCLEAR) return deterministic;
+  if (typeof semanticClassifier !== 'function') return deterministic;
+  const normalized = normalizeText(text);
+  if (!RESET_TARGETS.test(normalized) && !CONTEXT_REFERENCES.test(normalized) && !SESSION_SEMANTIC_HINT.test(normalized)) {
+    return deterministic;
+  }
+  try {
+    const semantic = normalizeSemanticResult(await semanticClassifier({
+      text: String(text ?? '').trim(),
+      actions: Object.values(WECHAT_SESSION_ACTION),
+    }));
+    if (semantic) return semantic;
+  } catch (err) {
+    logger?.warn?.('[wechat-session-intent] semantic classifier failed:', err);
+  }
+  return deterministic;
+}
+
+export function isWechatSessionResetAction(result) {
+  return result?.action === WECHAT_SESSION_ACTION.RESET;
+}