In cross-project BQ setups (where billing != data), the SA typically has
serviceusage.services.use on the billing project but not on the data
project. The rewriter passed bq.projects.data as the first arg to
bigquery_query(), which BQ uses as the execution + billing project →
403 USER_PROJECT_DENIED.
Match the convention used everywhere else in the codebase
(app/api/v2_scan.py, app/api/v2_sample.py, app/api/v2_schema.py,
connectors/bigquery/extractor.py): backtick paths inside the inner SQL
use the **data** project (resolves the actual table location), the
bigquery_query() first arg uses the **billing** project (decides who
pays + which project the job runs under). For single-project deploys
the two are identical so the fix is a no-op there.
Test pins the cross-project case: data-prj for backticks, billing-prj
for the bigquery_query() first arg.
81d065b1ea