Under the A2 trust model the connector is the SOLE crypto/identity
boundary: it verifies/decrypts every inbound platform payload at the edge
(it holds the tenant secrets), normalizes to a tenant-scoped MessageEvent,
and forwards only the sanitized event. The gateway re-validates nothing —
it cannot without being handed the shared signing secret, which on a
shared bot is itself the cross-tenant leak.
The relay path already imports no platform-crypto today; this locks that
in as an enforced invariant so nobody bolts re-validation (Discord
ed25519, Twilio HMAC, WeCom BizMsgCrypt, generic webhook signature checks)
onto the relay later and silently re-couples the gateway to platform
secrets it must never hold. Verification stays in the direct platform
adapters (gateway/platforms/*) which serve non-relay deployments.
- test_relay_package_imports_no_platform_crypto: AST-walks gateway/relay/*
and fails on any import of a platform-crypto/verification module.
- test_relay_package_calls_no_signature_verification: fails on any
verification-symbol reference (ed25519/hmac/bizmsg/verify_*).
Invariants (assert the relation 'relay re-validates nothing'), not frozen
snapshots. Verified the guard bites: injecting a wecom_crypto import makes
it fail, removing it goes green. docs §6 rewrite follows in a later commit.
c28a02b49d