## What kind of change does this PR introduce?
Docs update. Aligns documentation and style guides with the **Sign in /
Sign out / Sign up** platform standard.
Closes DOCS-1328. Related to
[#49874](https://github.com/supabase/supabase/pull/49874).
## What is the current behavior?
Docs style guides prefer _login_ / _log in_. Guide prose uses mixed
login and sign in wording.
## What is the new behavior?
- [WORD_LIST.md](apps/docs/WORD_LIST.md) and
[copywriting.mdx](apps/design-system/content/docs/copywriting.mdx)
document the sign in standard
- Design-system auth examples updated
- Guide prose and API reference spec descriptions updated
### Terminology
**Standard:** Use _sign in_, _sign out_, and _sign up_ as verbs. Use
_sign-in_, _sign-out_, and _sign-up_ as nouns and adjectives. Match
Studio UI labels (**Sign in**, **Sign out**, **Sign up**).
**Preserved intentionally:**
| Category | Keep as-is | Example |
| -------- | ---------- | ------- |
| Feature name | social login | `/social-login`, `features.mdx` heading,
OAuth provider section |
| URL slugs | `login` in paths | `/phone-login`, `/login-flows`,
`choosing-login-flow` |
| CLI | `supabase login` / `supabase logout` | Reference ids
`supabase-login` / `supabase-logout`; executable commands unchanged |
| SDK methods | `logout()` | Kotlin/Swift method names in API reference
titles and examples |
| Third-party UI | Provider product labels | Facebook Login, Kakao
Login, portal **Login** buttons |
| Postgres | Database terminology | login privileges, login credentials,
login via role |
| Audit/logging | Log prose | "Generates the following **log** in the
Postgres Logs" |
| Code and routes | Paths and filenames | `app/login/`, `Login.tsx`,
`demos/android-login` |
| External URLs | Third-party login pages | `dash.cloudflare.com/login`,
`console.neon.tech/login`, `vercel.com/login` |
| API identifiers | Event and field names | Audit actions
`login`/`logout`, `should_logout_user` |
## To test
- Run `pnpm lint:mdx` in `apps/docs`
- Spot-check `features.mdx`, `social-login.mdx`, and a provider guide
(e.g. Facebook, Kakao)
<!-- This is an auto-generated comment: release notes by coderabbit.ai
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## Summary by CodeRabbit
* **Documentation**
* Standardized authentication terminology across guides, reference
material, CLI documentation, and copywriting guidance using “sign in,”
“sign out,” and “sign up.”
* Updated authentication instructions, headings, link text, examples,
and SSO guidance for clearer, more consistent wording.
* Corrected related grammar, spelling, hyphenation, and documentation
links while preserving established product names and implementation
commands.
* **Style**
* Refined code examples with consistent import ordering and spacing.
* **Examples**
* Updated authentication button and menu labels to “Sign in” and “Sign
out.”
<!-- end of auto-generated comment: release notes by coderabbit.ai -->
Closes DOCS-1176
## Summary
This PR adds documentation-writing guidance for humans and agents, then
applies it to the “Securing your API” guide.
## Changes
- Add a documentation word list based on Google’s style guide and
existing MDX lint rules.
- Add a shared `docs-guides` Agent Skill with Cursor and Claude
integration.
- Expand contributing guidance for information types, procedures,
chunking, links, admonitions, grammar, and terminology.
- Restructure “Securing your API” into contextual and procedural
sections.
- Add section navigation, cross-references, transitions, and procedural
outcomes.
- Reduce repeated admonitions and improve scannability.
## Manual testing
1. Open `/docs/guides/api/securing-your-api` in Preview and compare to
Live.
https://docs-git-docs-restructure-api-supabase.vercel.app/docs/guides/api/securing-your-api
2. See that the content is improved and clear with no important context
removed.
3. See the Admonitions that are no longer marked as admonitions. See the
content still makes sense.
4. Review the diff of `CONTRIBUTING.md` and `WORD_LIST.md`.
5. See that you agree with the new rules and that they are clear.
<!-- This is an auto-generated comment: release notes by coderabbit.ai
-->
## Summary by CodeRabbit
* **Documentation**
* Updated documentation-writing guidelines with clearer standards for
structure, formatting, components, diagrams, terminology, and
navigation.
* Added a comprehensive word and style reference for consistent
documentation language.
* Reworked the API security guide with clearer guidance on grants, RLS,
dedicated schemas, pre-request checks, rate limiting, and API keys.
* Added documentation authoring workflow guidance, including validation
and formatting steps.
<!-- end of auto-generated comment: release notes by coderabbit.ai -->
