DL-347

Multi-actor comms coverage is tiered: cross-agent conversation, fan-out/isolation, and offline redelivery are asserted at the podman e2e tier with agent authorship carried by the real Runner session→account binding (no per-agent credential — relay_comms.go:7-15), and a non-admin observer client proves the credentialed transport path; the D9 visibility/leak matrix stays at the pgtest tier with e2e proving only one transport positive+negative. every agent-reachable relay arm is covered by a unit test at the runnerhub tier (podman is spent on the tool→relay→server JOIN, never on arm dispatch), and each native agent tool has at least one real-server execution. No new build tag or CI tier — new legs ride the existing e2e skip-guard

Status: Active (Matt, 2026-09-08)

Record: ../../server/compass-comms-multi-actor-test-coverage/design.md#resolved-decisions