R2.1: Tenant context derivation

Short answer: Derive tenant context from verified session, never client payload. A tenant id in the request body lets one customer read another customer’s data.

Group: Security and tenancy. Status: stable. Generated from the rule definitions; do not edit by hand.

Playground: https://brevio.pro/tools/agent-guard-playground?rule=R2.1

What it catches

Tenant context derivation: derive tenant context from verified session, never client payload.

Why

A tenant id in the request body lets one customer read another customer’s data.

A bad example

const tenantId = req.body.tenantId;

A good example

const tenantId = session.tenantId;

How it is checked

A one-line card in the prompt of a slice that touches matching files (dev_rules.slice_micro_rules).

How to silence it

A person can silence one finding with brevio-core: ignore R2.1 -- reason on the line or the line above. Without the reason it does not count. An agent cannot silence it: the agent hook and the MCP tools never honour the comment, and a pull request that adds one is reported until a reviewer allows it. Fixing the code is still the better answer.

To change what the rule flags, edit its definition in dev_rules.py or code_rules/__init__.py. That is a code change and is reviewed like one.

R2.2 Tenant-scoped data access
R2.3 Dual-key entity resolution
R2.4 Raw-body webhook verification
R2.5 Outbound SSRF & timeout guard
Every rule