[Headroom Vercel SDK](https://headroom-docs.vercel.app/docs)
Headroom’s Compress Cache Retrieve pattern as part of a MCP server
```mermaid
sequenceDiagram
participant Client
participant MCP as MCP Server
participant Headroom
participant CCR as Context Store
participant Retrieval as CCR Retrieval
participant LLM
%% Initial request
Client->>MCP: Send request
MCP->>Headroom: Forward full context: `compress`
%% Compression + storage
Headroom->>CCR: Store full context
Headroom->>LLM: Send compressed prompt
%% LLM asks for more info
LLM-->>Headroom: Tool call (need more data)
Headroom-->>MCP: Forward tool request
%% Retrieval flow (now explicit)
MCP->>Retrieval: Invoke retrieval tool `ccr_retrieve`
Retrieval->>CCR: Fetch full context
CCR-->>Retrieval: Return data
Retrieval-->>MCP: Return relevant chunk
%% Retry with more context
MCP->>Headroom: Send enriched prompt
Headroom->>LLM: Resend request
LLM-->>Headroom: Final response
Headroom-->>MCP: Forward response
MCP-->>Client: Final answer
```