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From the documentation:
When the last event in the score is played by a next message, there is no note following that one, so a unique delta time of -1 is sent out to signal that the last note has been played.
That -1 value might be what you need to look for (I have never used detonate myself) and then retrigger the playback. Not sure if this is helpful since the doc seems to suggest that the -1 is only sent when using the next message, but it's something.