fix: handle mention-only messages

[JSerFeng]

What this PR does

Rome prompted me to mention it in a Lark group to bind that group. I mentioned the bot without adding any text, but Rome did not respond.

The Lark SDK normalizes an @-only text message to an empty content string. The Feishu adapter treated that event like an unsupported media-only message and dropped it. An @-only text message now enters the normal inbound path as hello.

Just an idea, close this at any time if there is a better solution, as I'm not expert of agent development

[yunfanye]

Code Review: ✅ APPROVE

This PR handles the Feishu/Lark SDK’s mention-only normalization at the provider boundary: an empty normalized text event that mentions the bot becomes hello, while empty media events remain dropped. I fully reviewed both changed files, traced delivery through the Feishu connection integration and inbox message hook, and verified the pinned SDK’s normalization behavior; the design stays provider-specific and does not alter shared contracts.

Validation passed with Biome on both changed files, the full @rome/core typecheck, and feishu.test.ts (30 tests).

Verdict: APPROVE — The change is narrowly scoped, preserves existing media filtering and mention policy, and adds a regression test that covers the reported behavior.

No issues found. Code looks good!

---

Automated review by RomeOS Code Review · commit db04acd

[yunfanye]

Merging this fix as written so mention-only messages stop disappearing.

A follow-up should preserve the visible mention as @${this.channel.botIdentity?.name ?? "Rome"} rather than rewrite it to hello. That keeps the stored transcript faithful to what the user sent. The same normalization should cover Discord, where stripping a bot-only mention also leaves an empty message.

[yunfanye]

Follow-up opened in #54. It preserves bare mentions as @<bot name> for both Feishu/Lark and Discord while keeping normal addressed prose clean.

[zoolsher]

@JSerFeng Thanks for your contribution!