[Issue]: Gemini provider uses incorrect /v1/ endpoint

[SpicyMarinara]

Summary

Google Gemini provider requests return 404 errors and the model list cannot be fetched because Marinara Engine appends /v1/ instead of /v1beta/ to the endpoint.

Expected behavior

The Google Gemini provider should use the /v1beta/ endpoint so Gemini model requests and model list fetching succeed.

Actual behavior

Marinara Engine uses the /v1/ endpoint, causing 404 errors when calling Gemini models and preventing the model list from being fetched.

Steps to reproduce

1. Install or run Marinara Engine 2.4.2 (dd77689) through Termux on Android 16.
2. Configure the Google Gemini provider.
3. Attempt to fetch the model list or call a Gemini model.
4. Observe a 404 response caused by the request using /v1/ instead of /v1beta/.

Environment

• Marinara Engine version: 2.4.2 (dd77689)
• Install type: termux
• OS + version: Android 16
• Browser or app shell: Not provided

Logs, screenshots, or video

No logs or attachments provided. Gemini API method reference: https://ai.google.dev/api/all-methods

Additional context

The reporter initially referred to SillyTavern but clarified that the affected application is Marinara Engine.

Discord thread: Bug report - Gemini provider has wrong endpoint
Discord thread link: https://discord.com/channels/1417099416812392641/1536304459217371146
Requested by: Marinara (marinara_spaghetti, Discord ID 169561011928432653)

Discord thread transcript (6 messages)

[2026-08-10T09:25:26.234Z] Fussel: ME version: 2.4.2 (dd77689)
Installation method: Termux (Android 16)

When I try to call a Gemini model over the Google Gemini provider in Marinara Engine it results in a 404 error.
The reason it does that (and does not let me fetch the model list) is because the endpoint ME appends /v1/ when it should be with /v1beta/

See:
https://ai.google.dev/api/all-methods
All methods  |  Gemini API  |  Google AI for Developers
[Discord message: https://discord.com/channels/1417099416812392641/1536304459217371146/1536304459217371146]

[2026-08-10T09:31:58.268Z] Marinara: And this is ME’s problem how?
[Discord message: https://discord.com/channels/1417099416812392641/1536304459217371146/1536306103527153734]

[2026-08-10T09:32:06.405Z] Marinara: You should raise it on ST forum.
[Discord message: https://discord.com/channels/1417099416812392641/1536304459217371146/1536306137656336495]

[2026-08-10T09:33:14.719Z] Fussel: Sorry, for some reason I wrote SillyTavern and meant Marinara Engine 😅
[Discord message: https://discord.com/channels/1417099416812392641/1536304459217371146/1536306424186015846]

[2026-08-10T09:33:31.060Z] Fussel: That's on me
[Discord message: https://discord.com/channels/1417099416812392641/1536304459217371146/1536306492725002302]

[2026-08-10T09:33:37.716Z] Marinara: (no text content)
[Discord message: https://discord.com/channels/1417099416812392641/1536304459217371146/1536306520642420876]

Template check

Please uncheck (untick) the box below before submitting so we know you read the template. It is intentionally pre-checked:

• I DID NOT read this template and provide the requested details.

[SpicyMarinara]

Implementation is now owned by @SpicyMarinara in draft PR #4856.