Problem

Messages sent via the Feishu adapter could be silently dropped with zero observability — no error log, no warning, no trace. This made it impossible to diagnose why a message never reached the user.

Root Cause

Two gaps in the delivery chain combined to create a black hole:

1. stream_consumer.py _send_new_chunk(): When adapter.send() returns success=False, the method silently sets _edit_supported = False and returns reply_to_id — no log, no retry, no alert. Any failed send is completely invisible.

2. feishu.py send() and _finalize_send_result(): Neither the send attempt nor its result were ever logged. A failed API call (e.g. invalid post payload, rate limit, permission error) would return SendResult(success=False) which the stream consumer then silently swallowed.

3. feishu.py thread_id resolution: Some Feishu message events provide root_id but not thread_id. Without the root_id fallback, topic replies could fail to route correctly — another silent failure path.

Fix

1. stream_consumer.py — Log send failures

# Before: silent swallow
else:
    self._edit_supported = False
    return reply_to_id

# After: log with full context
else:
    self._edit_supported = False
    logger.warning(
        "[StreamConsumer] Send failed (success=%s, msg_id=%s, error=%s) "
        "chat=%s reply_to=%s text_len=%d",
        result.success, result.message_id, getattr(result, "error", None),
        self.chat_id, reply_to_id, len(text),
    )
    return reply_to_id

2. feishu.py — Add delivery logging to send()

Each chunk send now logs: chat_id, reply_to, chunk index, msg_type, payload_len, content_len.

3. feishu.py — Add result logging to _finalize_send_result()

• Success: logger.info("[Feishu] send succeeded: msg_id=%s", msg_id)
• Failure: logger.warning("[Feishu] send failed: code=%s msg=%s", code, msg)

4. feishu.py — Add root_id fallback for thread_id

# Before
thread_id=getattr(message, "thread_id", None) or None,

# After  
thread_id=getattr(message, "thread_id", None) or getattr(message, "root_id", None) or None,

Impact

• Zero behavioral changes — all fixes are logging-only (patches 1-3) or a defensive fallback (patch 4)
• Any future silent drop will now produce at least two log entries: one from the feishu adapter and one from the stream consumer
• The root_id fallback fixes a known issue where Feishu topic replies could fail to route when thread_id is not present in the message event

Testing

• Verified syntax with py_compile.compile() for both files
• Tested Feishu API directly with markdown table payloads (create, reply, reply_in_thread) — all return code:0
• Confirmed the fix branch applies cleanly to main