6.1.0 — more than one warehouse data source

A deployment can query more than one warehouse database, including
databases on different servers. Existing setups keep working unchanged.

Added

• Multiple warehouse data sources (PR #131). project_config/datasources.yaml is optional and lists named sources. Each source names only the environment variable holding its connection string, for example url_env: DB_URL_MAIN. The connection string itself stays in .env, because project_config/ is versioned and reviewed.
  • Without the file there is one source, default, using DB_CONNECTION_URL, exactly as before.
  • A template is in project_config.example/datasources.example.yaml; the design and roadmap are in docs/design/DATASOURCES.md.
• Each table names its source (PR #131). A schema.yaml table may set datasource:; a table without it belongs to the default source. Several databases on one server are one source: a table in another database on that server sets a multi-part db_schema: "OtherDb.dbo", rendered [OtherDb].[dbo].[Table].
• Queries are routed by their tables (PR #131). The source is derived from the tables a query reads, never chosen by the model. One query runs on one source. A query whose tables span two sources is refused with the new guard reason cross_datasource, and the web UI explains why in Persian.
• Every source is checked (PR #131).
  • Startup refuses an application database that matches any source, and a table assigned to a source that is not configured. Admin-panel schema.yaml drafts are checked the same way.
  • /health pings every source; database_detail names each one when there are several.
  • scripts/verify_deployment.py and the admin panel run the connectivity, read-only login, row cap and query timeout checks once per source.
  • Schema drift compares each source's tables against that source's own server.
• The audit record names the data source (PR #131). The new datasource field is the source the query's SQL targeted. Older records simply lack it.

Upgrading

• No action needed for a single-database setup.
• To add a second database on the same server, keep one source and give the table a multi-part db_schema, such as OtherDb.dbo.
• To add a database on another server, copy datasources.example.yaml to project_config/datasources.yaml, set one DB_URL_* variable per source in .env, add datasource: to that server's tables in schema.yaml, and restart. Create the read-only login on every source's server (docs/db-hardening.md), then run python scripts/verify_deployment.py.
• Changing datasources.yaml needs a restart.