Make genai prices auto-update in the worker

[petyosi]

We keep the prices in memory, I believe this should be good enough for a worker? Auto-updating every 30 minutes, as Samuel suggested. The update is non-blocking.

[Copilot]

Pull Request Overview

This PR implements automatic price data updates for the AI gateway by introducing a new price auto-update mechanism that fetches and caches provider pricing data from the @pydantic/genai-prices package.

• Adds a new setupPriceAutoUpdate module with TTL-based caching (30-minute refresh interval)
• Integrates the price update setup into the main request handler
• Implements concurrent fetch prevention and stale data handling logic

Reviewed Changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 4 comments.

File	Description
gateway/src/setupPriceAutoUpdate.ts	New module implementing price data auto-update with caching, TTL management, and integration with the genai-prices package
gateway/src/index.ts	Integrates price auto-update by calling setupPriceAutoUpdate at the start of each gateway request

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[alexmojaki]

Personally, I think this is unnecessary, as this will tax one unlucky request every 30 minutes.

I think it should be running in the background and the calculation should be using whatever latest data is already present. That data should be replaced independently.

[Copilot]

Pull Request Overview

Copilot reviewed 3 out of 4 changed files in this pull request and generated 7 comments.

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[alexmojaki]

I'm confused how this is non-blocking. refreshGenaiPrices() returns waitForUpdate() which returns providerDataPromise which should be freshDataPromise.