docs: add Neon AI Gateway endpoint guide

content/docs/configuration/librechat_yaml/ai_endpoints/meta.json

@@ -18,6 +18,7 @@
     "mlx",
     "moonshot",
     "nearai",
+    "neon",
     "neurochain",
     "ollama",
     "openrouter",

content/docs/configuration/librechat_yaml/ai_endpoints/neon.mdx

@@ -0,0 +1,75 @@
+---
+title: Neon AI Gateway
+description: Configure Neon AI Gateway as a custom endpoint in LibreChat.
+---
+
+Neon AI Gateway is an OpenAI-compatible inference gateway provided by Neon. A single Neon credential gives you access to models from OpenAI, Google, Meta, Databricks, and Alibaba, so you do not need separate provider accounts.
+
+<Callout type="warning" title="Paid plans and regional availability">
+
+Neon AI Gateway is generally available. It requires a paid Neon plan and is not available in every region; see [Regions](https://neon.com/docs/introduction/regions) for current coverage.
+
+</Callout>
+
+## Get a credential
+
+In the [Neon Console](https://console.neon.tech/), select your branch, click **Credentials** under **APP BACKEND**, then **Create credential** and check the `ai_gateway:invoke` scope. Neon shows the credential only once, so copy it before closing the dialog.
+
+You can also create one through the Neon API:
+
+```bash
+curl -X POST "https://console.neon.tech/api/v2/projects/{project_id}/branches/{branch_id}/credentials" \
+  -H "Authorization: Bearer $NEON_API_KEY" \
+  -H "Content-Type: application/json" \
+  -d '{"scopes": ["ai_gateway:invoke"], "principal_type": "user"}'
+```
+
+Add the credential to your `.env` file:
+
+```bash filename=".env"
+NEON_AI_GATEWAY_TOKEN=nt_live_your-credential-here
+```
+
+## Find your branch host
+
+Every Neon branch has its own gateway host, so there is no single URL that covers a whole account. The Neon Console shows the host for a branch on the AI Gateway page as `NEON_AI_GATEWAY_BASE_URL`, written below as `https://<your-neon-branch-host>`. It is not the same as your database connection string.
+
+Chat completions live at `/v1/chat/completions`, so the `baseURL` is the branch host with `/v1` appended.
+
+## Configuration
+
+Add the endpoint under `endpoints.custom` in your `librechat.yaml`:
+
+```yaml filename="librechat.yaml"
+    - name: "Neon AI Gateway"
+      apiKey: "${NEON_AI_GATEWAY_TOKEN}"
+      baseURL: "https://<your-neon-branch-host>/v1"
+      models:
+        default: ["gpt-5-mini"]
+        fetch: true
+      titleConvo: true
+      titleModel: "gpt-5-mini"
+      modelDisplayLabel: "Neon"
+```
+
+To keep the host out of `librechat.yaml`, put the full URL including `/v1` in an environment variable and reference it:
+
+```yaml filename="librechat.yaml"
+      baseURL: "${NEON_GATEWAY_URL}"
+```
+
+To pin a fixed model list instead of fetching the catalog, set `fetch: false` and name the models yourself:
+
+```yaml filename="librechat.yaml"
+      models:
+        default: ["gpt-5-mini", "gemini-3-flash", "qwen3-next-80b-a3b-instruct"]
+        fetch: false
+```
+
+## Notes
+
+- Neon implements `GET /v1/models`, so `fetch: true` works and returns only the models your branch can serve. The catalog is small, so fetching it does not slow down the model list.
+- Model IDs are short, for example `gpt-5-mini`, `gemini-3-flash`, or `llama-4-maverick`. The [Neon model catalog](https://neon.com/docs/ai-gateway/models) lists context windows and pricing, and the same catalog is browsable on [Models.dev](https://models.dev/providers/neon/).
+- Because the host is per branch, add one custom endpoint per Neon branch you want to reach, each with its own `name`.
+- A `403` means the credential lacks the `ai_gateway:invoke` scope or does not cover the branch you are calling. A `429` with error code `REQUEST_LIMIT_EXCEEDED` is a Neon account quota, not a LibreChat error; check the `Retry-After` header.
+- Open-weight models are available to every project immediately, while frontier models from OpenAI and Google roll out gradually, so a model listed in the catalog may not yet be enabled on your project.