## Context
Back to working on the [RLS
Tester](https://github.com/orgs/supabase/discussions/45233), slowly
adding support for mutation queries. First part here will be to add
support for testing `INSERT` based queries (Note that there's no changes
to the sandbox stuff in this PR)
## Changes involved
- If testing an `INSERT` query, we show a big warning first that the
query will be ran on the actual DB
- Note that we skip the warning if the sandbox is used
<img width="534" height="231" alt="image"
src="https://github.com/user-attachments/assets/ef75a0c9-61e4-49b0-9d78-458e8e5f7f4f"
/>
- If the testing as an anon user + RLS enabled
<img width="601" height="386" alt="image"
src="https://github.com/user-attachments/assets/b21f048d-bac1-4ddd-b84b-c231ae9f9e3e"
/>
- If testing as an auth-ed user + RLS enabled, but the INSERT violates
RLS (conditions don't meet)
<img width="604" height="489" alt="image"
src="https://github.com/user-attachments/assets/41c40486-48d5-4eee-b7cd-8f993edc47be"
/>
- Else if testing as an auth-ed user + RLS enabled and INSERT matches
RLS
<img width="612" height="402" alt="image"
src="https://github.com/user-attachments/assets/41854b40-b351-408b-8d23-cc5e0fa40813"
/>
- Minor cosmetic layout change here
- Use layout horizontal
- Also added the user ID below the dropdown with click to copy action
for convenience
<img width="615" height="528" alt="image"
src="https://github.com/user-attachments/assets/b9c04395-5435-474a-b3c5-640143faa782"
/>
- Added inline guard againsts some conditions
- Should not be able to run UPDATE or DELETE queries
<img width="622" height="319" alt="image"
src="https://github.com/user-attachments/assets/351af7c6-8f1e-47ae-8651-3b9b0b512490"
/>
- Should not be able to run multiple queries
<img width="612" height="317" alt="image"
src="https://github.com/user-attachments/assets/603d9a1f-1d1f-40f2-806d-93aea6b6cf8e"
/>
## To test
- [ ] Verify that the RLS Tester works as expected for an insert query
- Against actual DB
- Against sandbox (only available on staging)
- [ ] Verify that inline guards are all working as expected
- Let me know if there's any edge cases I might have missed!
<!-- This is an auto-generated comment: release notes by coderabbit.ai
-->
## Summary by CodeRabbit
* **New Features**
* RLS Tester results are now operation-aware (SELECT vs mutations), with
clearer “no rows/all rows” and policy evaluation explanations.
* Added copy-to-clipboard for the impersonated user ID.
* Query parsing now surfaces richer context, including WHERE clause
details and statement count, and SELECT-only previews.
* **Bug Fixes**
* Improved handling of blocked mutation queries and RLS-related error
messaging.
* Updated RLS Tester navigation to the correct policies page.
* Refined sandbox-assisted execution flow and empty/error states.
<!-- end of auto-generated comment: release notes by coderabbit.ai -->
## Context
Resolves FE-3077
Related discussion: https://github.com/orgs/supabase/discussions/45233
Verifying the correctness of your RLS policies set up has always been a
gap, as highlighted by a number of GitHub discussions like
[here](https://github.com/orgs/supabase/discussions/12269) and
[here](https://github.com/orgs/supabase/discussions/14401). As such,
we're piloting a dedicated UI for RLS testing (using role impersonation
as the base), in which you'll be able to
- Run a SQL query as a user (not logged in / logged in - this is the
role impersonation part)
- See which RLS policies are being evaluated as part of the query
- And hopefully be able to debug which policies are not set up correctly
Changes are currently set as a feature preview - and we'll iterate as we
get feedback from everyone 🙂🙏
<img width="613" height="957" alt="image"
src="https://github.com/user-attachments/assets/83c37f8a-28fc-43b3-b0ff-e28571d8710c"
/>
<!-- This is an auto-generated comment: release notes by coderabbit.ai
-->
## Summary by CodeRabbit
* **New Features**
* RLS Tester: run queries as anon or authenticated users, view inferred
SQL, per-table policy summaries, and data previews of accessible rows.
* UI preview: new RLS Tester preview card and modal with opt-in toggle;
RLS Tester sheet with role/user selector and query editor.
* SQLEditor: “Explain” tab is always visible.
* **Chores**
* Added supporting API endpoints, background checks for table RLS
status, and a local-storage flag to persist the preview opt-in.
<!-- end of auto-generated comment: release notes by coderabbit.ai -->
