[Docs]: Update Supabase's docs to reference CedarJS instead of Redwood

[Tobbe]

Our docs at https://cedarjs.com/docs/how-to/supabase-auth link to Supabase's RW docs. We should update those docs, or create new ones, and link to Cedar docs instead

https://supabase.com/docs/guides/getting-started/tutorials/with-redwoodjs

Are you interested in working on this?

• I'm interested in working on this

[github-actions]

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[lisa-assistant]

Implementation Plan

The issue has two parts: (1) updating the Cedar how-to doc that links to Supabase's outdated Redwood guide, and (2) working with Supabase to update their external documentation. They're independent and (1) can be done without (2).

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Part 1 — Update the Cedar how-to doc (in-repo)

File: docs/docs/how-to/supabase-auth.md

The page links to https://supabase.io/docs/guides/with-redwoodjs (line 26) as a prerequisite called "Go through the Supabase Cedar Quick Start". That URL no longer makes sense — Supabase's Redwood guide covers the old redwoodjs setup, not Cedar's.

Fixes in docs/docs/how-to/supabase-auth.md:

1. Line 26 — Replace the broken prerequisite link:

   • Old: [Go through the Supabase Cedar Quick Start](https://supabase.io/docs/guides/with-redwoodjs)
   • New: [Set up Supabase Auth in your Cedar app](../auth/supabase.md)

   The replacement links to the canonical Cedar Supabase auth doc at docs/docs/auth/supabase.md, which already exists and covers the full setup in Cedar terms.

2. Line 691 — The "Cedar Auth Playground" link points to https://redwood-playground-auth.netlify.app/supabase. This is an old Redwood playground — either update it to a Cedar playground if one exists, or remove the dead link.

3. Domain update — Replace supabase.io URLs with supabase.com (Supabase migrated domains).

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Part 2 — Request/contribute a CedarJS guide to Supabase's docs

Supabase's docs are open source at github.com/supabase/supabase (in apps/docs/).

Steps:

1. Open a GitHub issue in supabase/supabase requesting a CedarJS tutorial, referencing the old Redwood one at apps/docs/content/guides/getting-started/tutorials/with-redwoodjs.mdx.
2. Or open a PR that adds a new with-cedarjs.mdx tutorial (a port of the Redwood one using Cedar CLI commands and @cedarjs/* imports), or updates the existing Redwood tutorial to note that CedarJS is the successor.

The Supabase Redwood tutorial covers: creating the project, setting up the database, adding auth, building the UI, and deploying. A Cedar equivalent follows the same structure but uses yarn cedar setup auth supabase, @cedarjs/web, etc.

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Edge Cases

• The how-to doc (supabase-auth.md) is long (~700 lines) and uses GoTrue-based patterns that Supabase has since moved away from — a future issue might modernize this doc to use @supabase/ssr and Supabase's current auth approach.
• Don't remove or rename the how-to/supabase-auth.md page without setting up a redirect in docusaurus.config.ts — it may be linked externally.

[lisa-assistant]

Self-fix confidence: 8/10

Part 1 (the in-repo doc fix) is straightforward: 2-3 line changes in a markdown file with clear correct targets. Part 2 (contributing to Supabase's repo) is a good-faith collaboration effort that I could draft as a PR, but acceptance depends on the Supabase team.

The 2-point deduction is for: (1) I haven't verified that the Cedar Auth Playground link has a live replacement — if there's no Cedar playground yet, I'd need to decide whether to remove the line or leave it linking to the old Redwood one; (2) a more thorough fix would modernize the GoTrue-based patterns throughout the how-to doc to match Supabase's current auth SDK, which is a larger scope change.