fix(feishu): normalize all mentions in inbound agent context (#30252)

* fix(feishu): normalize all mentions in inbound agent context

Convert Feishu mention placeholders to explicit <at user_id="..."> tags (including bot mentions), add mention semantics hints for the model, and remove unused mentionMessageBody parsing to keep context handling consistent.

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

* fix(feishu): use replacer callback and escape only < > in normalizeMentions

Switch String.replace to a function replacer to prevent $ sequences in
display names from being interpolated as replacement patterns. Narrow
escaping to < and > only — & does not need escaping in LLM prompt tag
bodies and escaping it degrades readability (e.g. R&D → R&amp;D).

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

* fix(feishu): only use open_id in normalizeMentions tag, drop user_id fallback

When a mention has no open_id, degrade to @name instead of emitting
<at user_id="uid_...">. This keeps the tag user_id space exclusively
open_id, so the bot self-reference hint (which uses botOpenId) is
always consistent with what appears in the tags.

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

* fix(feishu): register mention strip pattern for <at> tags in channel dock

Add mentions.stripPatterns to feishuPlugin so that normalizeCommandBody
receives a slash-clean string after normalizeMentions replaces Feishu
placeholders with <at user_id="...">name</at> tags. Without this,
group slash commands like @Bot /help had their leading / obscured by
the tag prefix and no longer triggered command handlers.

Pattern mirrors the approach used by Slack (<@[^>]+>) and Discord (<@!?\d+>).

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

* fix(feishu): strip bot mention in p2p to preserve DM slash commands

In p2p messages the bot mention is a pure addressing prefix; converting
it to <at user_id="..."> breaks slash commands because buildCommandContext
skips stripMentions for DMs. Extend normalizeMentions with a stripKeys
set and populate it with bot mention keys in p2p, so @Bot /help arrives
as /help. Non-bot mentions (mention-forward targets) are still normalized
to <at> tags in both p2p and group contexts.

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

* Changelog: note Feishu inbound mention normalization

---------

Co-authored-by: Claude Sonnet 4.6 <noreply@anthropic.com>
Co-authored-by: Tak Hoffman <781889+Takhoffman@users.noreply.github.com>

extensions/feishu/src/channel.ts

@@ -88,6 +88,9 @@ export const feishuPlugin: ChannelPlugin<ResolvedFeishuAccount> = {
   groups: {
     resolveToolPolicy: resolveFeishuGroupToolPolicy,
   },
+  mentions: {
+    stripPatterns: () => ['<at user_id="[^"]*">[^<]*</at>'],
+  },
   reload: { configPrefixes: ["channels.feishu"] },
   configSchema: {
     schema: {