expose_in_sqllab flag ignored in SQL Lab database selector (6.1.0 regression)

[JhonMcLovin]

Bug description

After upgrading from Superset 6.0.0 to 6.1.0, SQL Lab displays databases where expose_in_sqllab = false.

Previously (6.0.0), these databases were correctly hidden from the SQL Lab dropdown, but in 6.1.0 they are shown regardless of the flag.

This breaks setups that rely on dual database configurations (separate DBs for Explore vs SQL Lab).

Screenshots/recordings

1. Create a database with:
   expose_in_sqllab = false

2. Create another database with:
   expose_in_sqllab = true

3. Ensure user has access to a dataset that uses the hidden DB

4. Open SQL Lab

5. Observe both databases appear in dropdown

Superset version

master / latest-dev

Python version

3.9

Node version

I don't know

Browser

Chrome

Additional context

Expected behavior
Databases with expose_in_sqllab = false should NOT appear in SQL Lab database selector.
Actual behavior
Databases appear in SQL Lab dropdown even when:

• expose_in_sqllab = false
• correctly stored in metadata DB
  Additional context
• API /api/v1/database returns entries with expose_in_sqllab=false
• SQL Lab frontend does not filter them out
• Role-based filtering is working correctly, but expose_in_sqllab is ignored

Checklist

• I have searched Superset docs and Slack and didn't find a solution to my problem.
• I have searched the GitHub issue tracker and didn't find a similar bug report.
• I have checked Superset's logs for errors and if I found a relevant Python stacktrace, I included it here as text in the "additional context" section.

[sadpandajoe]

@dosubot figure out the issue

[debabsah]

I looked into this since it overlaps with the SQL Lab database-selector area, and the obvious fix (re-adding a filter) may not be the right one. A few findings:

• The SQL Lab dropdown's own fetch is already scoped correctly. In SQL Lab mode, DatabaseSelector adds an expose_in_sqllab eq true filter alongside the name filter (superset-frontend/src/components/DatabaseSelector/index.tsx), and the list API allows that filter (expose_in_sqllab is in search_columns in superset/databases/api.py). That block is unchanged between 6.0.0 and 6.1.0.
• The SQL Lab bootstrap, however, seeds the store with every database unfiltered: bootstrap_sqllab_data iterates DatabaseDAO.find_all() with no expose_in_sqllab filter (superset/sqllab/utils.py). That has been the case since at least 6.0.0, so it is not itself the change, but it does mean the editor starts with hidden databases in state.

So this does not look like a removed filter; the unfiltered bootstrap state appears to be getting surfaced in the selector. That state handling is the same area being reworked in #41245 / #41281 (SET_DATABASES), so the two are likely related.

Happy to reproduce on 6.1.0, bisect 6.0.0 to 6.1.0 to pin the exact change, and open a small PR. Two questions first:

1. Intended behavior: should expose_in_sqllab = false databases be fully hidden from SQL Lab, including the bootstrap state, not just the dropdown query?
2. Would you prefer this be coordinated with fix(sqllab): preserve database state on SET_DATABASES #41281, since they touch the same path?