Pre-fix `agnes pull` decided what to download from sync_state hash
equality alone:
if server_hash != local_hash or tid not in local_tables or not server_hash:
to_download.append(tid)
If the recorded local hash matched server but the actual parquet had
been deleted from disk, the download was skipped. The next DuckDB
view rebuild then fails on a missing file. Repro: `rm
server/parquet/X.parquet && agnes pull` → 'Updated 0 tables', X
still missing.
Failure modes that produce hash-equal-but-file-missing:
- manual `rm` of a single parquet
- operator-side cleanup of `server/parquet/`
- two workspaces sharing one user's
`~/.config/agnes/sync_state.json` (TODO(workspace-scoped-sync-state)
in pull.py): one workspace writes its parquets, the other reads
sync_state and concludes 'I already have these'
- disk corruption / partial restore from backup
Fix: existence check runs alongside the hash compare. Missing file
forces a re-download regardless of hash equality. `parquet_dir` is
hoisted above the loop so the existence check is in scope when the
download set is built.
Tests: regression test for the hash-equal-but-missing-file case +
counterpart for the fast-path (hash-equal-and-file-present must
still skip).
