[Fix] Clamp Gemini 4 Argon limits to Google's values on Vercel AI Gateway

[zoomote]

​Opened on behalf of Toray Altas. Follow up by mentioning @roomote, in the web UI, or in Discord.

Related GitHub Issue

No linked issue. Follow-up to the merged #2043, requested by a maintainer (Toray Altas) via Discord: re-audit provider catalogs for Gemini 4 Argon and fix any wrong metadata.

Description

The Vercel AI Gateway catalog now lists google/gemini-4-argon, but reports context_window: 1,000,000 and max_tokens: 1,000,000. Google's authoritative limits are a shared 1,048,576-token window (input + thinking + output) and a 65,536-token single-request output cap, with longer decodes handled through continuation tokens.

This PR adds a per-model override in parseVercelAiGatewayModel (src/api/providers/fetchers/vercel-ai-gateway.ts) for google/gemini-4-argon, following the existing per-model override pattern used for openai/gpt-6-astra and others:

• contextWindow: 1,048,576 and maxTokens: 65,536 (Google's documented values, not the gateway's).
• supportsReasoningEffort: low, medium, high, with default medium.
• supportsTemperature: false (the Google backend ignores temperature/top_p/top_k on this model).

Zoo Gateway inherits the same override because it reuses parseVercelAiGatewayModel.

Provider re-audit results (all checked live):

Provider	Live catalog status	Change in this PR
Gemini Developer API (ai.google.dev)	Listed (Gemini 4, stable; paid tier only)	None — registry entry merged in #2043
Vertex AI	Listed; locations global, us, eu	None — registry entry merged in #2043
Vercel AI Gateway	Listed (google/gemini-4-argon); wrong context/max_tokens (1,000,000 each)	Per-model override (this PR)
Zoo Gateway	Same catalog/parser as Vercel AI Gateway	Inherits the override
OpenRouter	Listed (google/gemini-4-argon); metadata matches Google's values	None — dynamic catalog fetch
Requesty	Lists vertex/gemini-4-argon (and @eu)	None — dynamic catalog fetch
Unbound	No Gemini models in its catalog	None

No metadata deltas found for the entries merged in #2043; the registry values still match Google's documentation.

Test Procedure

• Added a parseVercelAiGatewayModel test in src/api/providers/fetchers/__tests__/vercel-ai-gateway.spec.ts asserting the clamped context window and max tokens, thinking levels, default effort, and supportsTemperature: false for google/gemini-4-argon.
• Fetcher suites (vercel-ai-gateway.spec.ts, zoo-gateway.spec.ts): 30/30 passed.
• pnpm run check-types in src: passed. ESLint clean on the touched files.
• Full pnpm test from the repository root, re-run after rebasing onto current main: 13/13 tasks green; the src suite alone is 539 test files, 10,819 tests passed. (zoo-code#test is intermittently flaky under the parallel turbo run in this environment; standalone and rerun results are green.)

Pre-Submission Checklist

• Issue Linked: No GitHub issue exists; follow-up requested by a maintainer via Discord (see "Related GitHub Issue").
• Scope: My changes are focused on the linked issue (one major feature/fix per PR).
• Self-Review: I reviewed my own code with care.
• Writing Style: The PR title and description use Simplified Technical English (ASD-STE100): short sentences, plain words, active voice, one idea per sentence, no contractions.
• Testing: New and/or updated tests have been added to cover my changes (if applicable).
• Visual Snapshot (UI changes only): Not applicable. This is a fetcher parser override; no layout, theme token, or rendered-state change. Behavior is covered by Vitest.
• Documentation Impact: I checked if my changes need documentation updates (see "Documentation Updates" section below).
• Contribution Guidelines: I read and agree to the Contributor Guidelines.

Visual Snapshots

Not applicable: no layout, theme, or rendered-state change.

Videos (interaction / animation only)

Not applicable: no new interaction flow or animation.

Documentation Updates

• No documentation updates are required.
• Yes, documentation updates are required. Paired docs PR: [Docs] Note third-party gateway availability for Gemini 4 Argon Zoo-Code-Docs#67 adds a third-party availability note for Gemini 4 Argon on the Google Gemini provider page.

Additional Notes

Sources: https://cloud.google.com/gemini-enterprise-agent-platform/models/guides/gemini-4-argon and the live Vercel AI Gateway, OpenRouter, and Requesty model catalogs.

Get in Touch

Toray Altas (taltas) on Discord.

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