ENABLE_PROMPT_CACHING_1H=1 Works?

[ironbelly]

https://github.com/anthropics/claude-code/releases/tag/v2.1.108 - Only available via API.. Now Claude code talks to cliproxyapi via API so it works? but then the proxy talks to Anthropic via oauth, so it doesn't work?

[ironbelly]

The litellm x-pass- workaround failed to change behavior, so litellm is probably not the culprit (header filtering would have been bypassed). The most likely cause is one of:

1. cliproxyapi strips or rewrites anthropic-beta headers on the OAuth-mediated path. This is the leading hypothesis — the project (router-for-me/CLIProxyAPI) normalizes requests for OAuth compatibility.
2. Anthropic's Max OAuth path itself doesn't accept extended-cache-ttl-2025-04-11. The March 2026 default downgrade from 1h → 5m may have actually been a capability removal on the subscription path, not
   just a default change. The ENABLE_PROMPT_CACHING_1H workaround may only work for Claude Code's native OAuth flow, which talks directly to Anthropic without an intermediary OAuth proxy.
3. cliproxyapi mutates the request body to strip ttl: "1h" from cache_control blocks.

#2599