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Store state between tool calls

Persist data across calls in a Glxymesh MCP tool with the built-in key/value store. Get, put, delete and list by prefix, scoping, and size limits.

Each call runs in a fresh WebAssembly instance, so package variables are reset every time. To keep data between calls, use host.KV.

API

import "glxymesh.com/mcp-core/host"

err := host.KV.Put("counter", []byte("41"))

value, found, err := host.KV.Get("counter")   // found is false for a missing key; that's not an error

err = host.KV.Delete("counter")

keys, err := host.KV.List("session:")         // every key that starts with the prefix

Keys are strings and values are bytes. Encode structured data yourself, for example with encoding/json.

Scope

Each tool has its own keyspace, keyed by organization, project and tool name. Two tools can use the same key without collisions, and no tool can read another tool’s data. Renaming a tool gives it a new, empty keyspace.

Limits


Key	up to 512 bytes
Value	up to 1 MiB

Keys aren’t locked between calls. If two calls update the same key at the same time, the last write wins.