Bug type

Regression (worked before, now fails)

Summary

Using volces/deepseek-v3-2-251201 model fails with 400 error: unknown field "prompt_cache_key"

Steps to reproduce

1. Configure volces provider with deepseek-v3-2-251201 model
2. Send a message to the agent
3. API request fails with error

Expected behavior

Agent should respond normally without API errors

Actual behavior

400 json: unknown field "prompt_cache_key" Request id: ...

OpenClaw version

2026.3.13

Operating system

Linux (Ubuntu 24.04)

Install method

No response

Model

volces/deepseek-v3-2-251201

Provider / routing chain

volces (Volcano Engine)

Config file / key location

No response

Additional provider/model setup details

No response

Logs, screenshots, and evidence

Impact and severity

No response

Additional information

Root cause: pi-ai library automatically adds prompt_cache_key and prompt_cache_retention fields to API requests. Volcano Engine DeepSeek API does not support these parameters.

Temporary workaround: Set cacheRetention: "none" in provider config.

Suggested fix: Check if base URL supports prompt cache before adding these fields, or add per-model config to disable prompt cache.