Answer "what would the other device end up with" without the other device

A tablet showed 200 of a person's 611 faces after syncing, and the obvious
suspects — that suggestions deliberately do not travel, that the cross-device
face match was too strict — were both wrong. Finding that out meant reading a
catalog on a release-signed Android build, which cannot be done.

So this stands the second device up locally: an empty catalog, given the images
a scan would have found, the shards adopted into it exactly as a sync does, and
the real catalog merged in as the remote. Then it counts, per person, against
what the source holds.

    person                     source     here
    Catherine                     611      611
    Me                            242      242
    Ian                           219      219

Which settled it: the merge carries everything, and the shortfall was transfer —
shards that never finished arriving. Worth keeping, because "did the sync lose
this or has it not got here yet" is a question that will come up again, and
guessing at it cost most of an evening.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

docs/traceability.md

@@ -9,7 +9,7 @@ Denominators are parsed from [`requirements.md`](requirements.md) at run time, n
 
 | Metric | Value |
 |---|---|
-| Source files scanned | 277 |
+| Source files scanned | 278 |
 | TRACES tags found | 811 |
 | Requirements defined | 177 |
 | Requirements covered | 106 |