mcp-tenant-context is a small, dependency-free library that propagates a per-request TenantContext (tenant slug + actor identity) through an AsyncLocalStorage. It performs no network, filesystem, subprocess, crypto or database operations. Its security relevance is narrow but real: it is the primitive that downstream servers build cross-tenant isolation on top of.

The property this library guarantees is context isolation: two concurrent runWithTenantContext scopes never observe each other's context. That property is covered by the test suite (nested, sibling-concurrent, async-iterator and detached-timer cases). A bug that breaks it — for example, one request reading another request's tenantSlug — is a security issue and in scope for this policy.

The library deliberately does not validate or sanitise its inputs. The following are the consumer's responsibility, and getting them wrong is the most likely way to turn a correct library into a vulnerable system:

• Validate tenantSlug before constructing a context (non-empty, expected charset, e.g. ^[a-z0-9][a-z0-9-]{0,62}$). An empty or attacker-controlled slug fed straight into WHERE tenant_slug = $1 is a cross-tenant risk.
• Parameterise SQL. tenantSlug is a plain string; never interpolate it.
• Verify email out of band (it comes from your OAuth/identity layer) and lowercase it before building an actor.
• Reject anonymous actors at the handler level where a tenant is required.

Please report suspected vulnerabilities privately. Do not open a public issue for a security report.

• Email: security@studiomeyer.io (or hello@studiomeyer.io)
• Preferred: GitHub private vulnerability reporting ("Report a vulnerability" on the repository Security tab).

Include a description, affected version, and a minimal reproduction if possible. We aim to acknowledge within 5 working days and to coordinate a fix and disclosure timeline with you. We credit reporters who want credit.

The latest 0.x release on npm receives security fixes. Pre-1.0, fixes ship as patch releases against the most recent minor.