## Summary
Remove the `hidden` tag from the `PromptCacheKey` field on
`ChatModelOpenAIProviderOptions` so the auto-generated JSON schema
no longer marks it as hidden. This allows the admin model
configuration UI to render a "Prompt Cache Key" text input for
OpenAI models alongside other visible options like Reasoning Effort,
Service Tier, and Web Search.
## Changes
- **`codersdk/chats.go`**: Remove `hidden:"true"` from `PromptCacheKey`
struct tag.
- **`site/src/api/chatModelOptionsGenerated.json`**: Regenerated via
`make gen` — `hidden: true` removed from the `prompt_cache_key` entry.
- **`modelConfigFormLogic.test.ts`**: Extend existing "all fields set"
tests to cover extract and build roundtrip for `promptCacheKey`.
## How it works
The `hidden` Go struct tag propagates through the code generation
pipeline:
1. Go struct tag → `scripts/modeloptionsgen` →
`chatModelOptionsGenerated.json`
2. The frontend `getVisibleProviderFields()` filters out fields with
`hidden: true`
3. Removing the tag makes the field visible in the schema-driven form
renderer
No new UI components are needed — the existing `ModelConfigFields`
component
automatically renders the field as a text input based on the schema
(`type: "string"`, `input_type: "input"`).
The field appears as **"Prompt Cache Key"** with description
"Key for enabling cross-request prompt caching" in the OpenAI provider
section of the admin model configuration form.
Michael Suchacz
f9c265ca6e