Here is a diff for turning the above script into a margaret-find.go tool that searches for a message key. Since we don't store the references as strings in base64 we need to compute the ref for each message again...

24,25c24,25
<     if len(os.Args) != 3 {
<         check(fmt.Errorf("usage: margret-find <log dir> <searchkey>"))
---
>     if len(os.Args) != 2 {
>         check(fmt.Errorf("usage: margret-dump.go <log dir>"))
35,39d34
<     // make sure we get a ref we understand
<     // and parse it means we can compare it without encoding it up to b64 again..!
<     searchRef, err := ssb.ParseMessageRef(os.Args[2])
<     check(err)
<
44,47c39
<     src, err := ofstLog.Query(
<         margaret.Reverse(true), // read last entries first
<         margaret.SeqWrap(true), // also get the sequence (so we don't have to keep track of it ourselvs)
<     )
---
>     src, err := ofstLog.Query(margaret.Limit(3))
49a42
>     i := 0
60,67c53
<         // go abstraction magic, now first unbox the sequence-value pair
<         sw, ok := msgv.(margaret.SeqWrapper)
<         if !ok {
<             check(fmt.Errorf("unexpected type: %T", msgv))
<         }
<         msgv = sw.Value() // message inside here
<
<         // now get the message type that's nice to work with
---
>         // go abstraction magic, get a message type that's nice to work with
73,79d58
<         i := sw.Seq()
<
<         if !msg.Key().Equal(*searchRef) {
<             // fmt.Println("not found, skipping",i)
<             continue
<         }
<
81c60,61
<         fmt.Printf("\n\nFound Message%02d: %s\n", i, msg.Key().Ref())
---
>         fmt.Printf("\n\nMessage%02d: %s\n", i, msg.Key().Ref())
>         i++