Bug: a Design Director coordinator with 6 freshly-created worker peers
rendered an empty `## Your Peers` section in its system prompt — the
hosting registry endpoint correctly returned all 6 peers, but
`summarize_peer_cards()` silently dropped every entry whose
`agent_card` column was null (the default until A2A discovery has
run end-to-end against the worker). The coordinator then refused to
delegate any task because "no peers exist".
Fix: fall back to the registry row's `name` and `role` columns when
`agent_card` is missing, malformed, or wrong-typed, instead of
skipping the peer. The registry endpoint
(`workspace-server/internal/handlers/discovery.go:queryPeerMaps`) has
always returned both fields — they were just being thrown away on
the consumer side. `build_peer_section()` now renders `Role: …` when
the agent_card-derived skill list is empty so the coordinator's
prompt still has something concrete to delegate against.
Also hoists `import json` out of the per-peer loop body to module
level (was previously imported once per iteration).
Tests: new `test_shared_runtime_peer_summary.py` pins all four
fallback cases (null / malformed string / wrong type / null + no
DB name) plus the agent-card-present happy path and the mixed-list
case the coordinator actually consumes. First peer-summary test
coverage `shared_runtime.py` has had — no prior tests existed.
Refs: 2026-04-27 Design Director discovery report from infra team.
8ff0748ab9