E2E testing showed admin POSTs of materialized BQ rows whose source_query
uses BigQuery-native backtick identifiers (`prj.ds.t`) silently no-op'd at
the next sync tick — the materialize path runs the SQL through the DuckDB
BQ extension's COPY which uses DuckDB's parser; backticks aren't recognized
and the query either parse-errors or matches zero rows. No parquet lands at
the canonical path and no error reaches an operator-visible surface.
Two-part fix:
1. RegisterTableRequest's _check_mode_query_coherence model_validator now
rejects any source_query containing a backtick with a 422 + actionable
message pointing at the DuckDB equivalent (bq."dataset"."table"). Same
check is applied in update_table on the merged record so PATCHes that
flip a stored source_query to backtick form are also caught. Covers BQ
AND Keboola materialized rows since both connectors funnel source_query
through DuckDB's COPY.
2. _run_materialized_pass now persists per-row failures via the new
SyncStateRepository.set_error / clear_error methods (existing
sync_state.error / status columns — no schema migration). GET
/api/admin/registry enriches each row with `last_sync_error` from a
single batched SELECT against sync_state, so the admin UI / da admin
status can show "this table failed last sync because: X" instead of
operators having to trawl scheduler logs. Recovered rows have the
error cleared automatically — update_sync's success path resets
status='ok' / error=NULL on the upsert.
The materialized-path test fixture's _materialized_payload helper is
updated to use DuckDB-flavor SQL (the prior backtick example pre-dated the
fix). 6 new tests cover register/update rejection on BQ + Keboola, the
sync_state error persistence, and the registry response surface.
