Three ways a chunk disappeared from a graph with no way to tell:
A build checks out one connection and then spends minutes per chunk waiting
on the model, so the connection idles long enough for the server or a pooler
to drop it. The pool only validates a connection when it hands one out, and
this one was handed out at the start of the build, so the next write raised
"the connection is lost", the chunk was marked failed, and the build carried
on a chunk short. apply_chunk and mark_chunk now reconnect and retry once;
every statement they run is an idempotent upsert, so a replay cannot
double-write. Only connection loss retries — a bad statement still surfaces.
An unparseable model response marked the chunk failed and logged nothing at
all, so failed_chunks was the only evidence and it named no chunk. Both
failure modes now log the chunk id.
The summary's node count summed per-chunk upserts, so an entity appearing in
ten chunks counted ten times: it reported writes, not graph size. It now
reports the distinct node count, falling back to the write count only if the
count query fails.
Alex
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