macOS Messages thread gaps come from handle rotation, not lost data

iMessage keys conversations in chat.db by handle (phone number or email), never by contact card. When a correspondent switches numbers, their history splits into two chat rows with non-overlapping date ranges, and the UI renders the surviving thread as jumping months at once — it looks like data loss but nothing is missing. Diagnose with: SELECT c.ROWID, c.chat_identifier, COUNT(*), MIN/MAX(datetime(m.date/1000000000+978307200,'unixepoch','localtime')) FROM chat c JOIN chat_message_join cmj ON cmj.chat_id=c.ROWID JOIN message m ON m.ROWID=cmj.message_id GROUP BY c.ROWID — the complementary date ranges give it away. Critical gotcha: on modern macOS message.text is NULL for nearly every row (check SUM(CASE WHEN text IS NULL THEN 1 END)); bodies live in the attributedBody binary plist, so LIKE queries against text silently return zero rows and you will wrongly conclude the messages are absent. Also note m.date is Apple epoch nanoseconds, and comparing it against strftime('%s') needs an explicit +0 cast or the comparison fails silently.