fix(core): ExtraContent lost after alias resolution

[xfromcnZL]

Summary

• ExtraContent (reply quotes, location text, etc.) was silently discarded during message processing
• Root cause: handleMessage correctly prepends ExtraContent to msg.Content, but the subsequent alias resolution uses the original content variable (without ExtraContent) and overwrites msg.Content
• Fix: pass msg.Content (which includes ExtraContent) to resolveAlias instead of the original content variable

Bug reproduction

1. User replies to a message in Discord (or any platform that sets ExtraContent)
2. enrichReplyContent correctly returns [Reply to user]: original message
3. Line 1342 correctly sets msg.Content = ExtraContent + "\n" + content
4. Bug: Line 1347 content = e.resolveAlias(content) uses the original content without ExtraContent
5. Line 1348 msg.Content = content overwrites the enriched content — reply context is lost
6. Agent never sees what the user was replying to

Changes

• core/engine.go: Changed resolveAlias(content) → resolveAlias(msg.Content) (1 line)

Test plan

• go test ./core/ -run Alias passes
• go build ./... passes
• Manual test: Discord reply now correctly delivers quoted context to the agent

🤖 Generated with Claude Code

[chenhg5]

LGTM. Correct fix — using msg.Content (which preserves ExtraContent prefix from reply quotes) instead of the already-stripped local variable. Simple and correct.

PR: #553

[chenhg5]

@xfromcnZL, please help resolve the current code conflicts. Thx.

[xfromcnZL]

Thanks for flagging the conflict @chenhg5.

After reviewing, main already fixes the same ExtraContent-loss bug with a better approach (resolve aliases on pure user text first, then merge ExtraContent back). This avoids the edge case where reply-quoted content could accidentally trigger an alias match.

Since the root cause is already addressed on main, closing this PR as superseded. 🙏