Demote Signal receipt/typing/sync spam from INFO to DEBUG

signalbot logs every received envelope at INFO via `[Raw Message] {json}`. On a
busy account the delivery/read receipts, typing indicators, and read-sync
messages flood journald hard enough to rotate the journal down to ~1 minute,
burying real traffic and making failures impossible to debug after the fact.

Add a logging filter on the `signalbot` logger that suppresses content-free
envelopes (anything without a `dataMessage`) at INFO, while still emitting them
if the logger is explicitly set to DEBUG. Real message content stays at INFO.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

bot.py

@@ -102,6 +102,24 @@ logging.basicConfig(
 )
 log = logging.getLogger("signal-bot")
 
+
+class _RawReceiptNoiseFilter(logging.Filter):
+    """signalbot logs every received envelope at INFO via `[Raw Message] {json}`.
+    On a busy account that's a flood of delivery/read receipts, typing indicators,
+    and read-sync messages that rotates the journal down to ~1 minute and buries
+    real traffic. Suppress the content-free envelopes (anything without a
+    `dataMessage`) unless the signalbot logger is explicitly set to DEBUG — so they
+    stay capturable when you actually want to debug raw traffic, but don't spam INFO."""
+
+    def filter(self, record: logging.LogRecord) -> bool:
+        msg = record.getMessage()
+        if msg.startswith("[Raw Message] ") and '"dataMessage"' not in msg:
+            return logging.getLogger("signalbot").isEnabledFor(logging.DEBUG)
+        return True
+
+
+logging.getLogger("signalbot").addFilter(_RawReceiptNoiseFilter())
+
 # (group_id, sender) -> {"b64": ..., "time": monotonic}. Keyed per sender so a
 # stranger's later video doesn't silently become the target of your /speed or
 # /rev; _get_video falls back to the group's latest video when you have none.