Closes#2397. Today, every empty-peer condition (true empty, 401/403, 404,
5xx, network) collapses to a single message: "No peers available (this
workspace may be isolated)". The user has no way to tell whether they need
to provision more workspaces (true isolation), restart the workspace
(auth), re-register (404), page on-call (5xx), or check network (timeout) —
five different operator actions, one ambiguous string.
Wire:
- new helper get_peers_with_diagnostic() in a2a_client.py returns
(peers, error_summary). error_summary is None on 200; a short
actionable string on every other branch.
- get_peers() now shims through it so non-tool callers (system-prompt
formatters) keep the bare-list contract.
- tool_list_peers() switches to the diagnostic helper and surfaces the
actual reason. The "may be isolated" string is removed; true empty
now reads "no peers in the platform registry."
Tests:
- TestGetPeersWithDiagnostic: 200, 200-empty, 401, 403, 404, 5xx,
network exception, 200-but-non-list-body, and the bare-list-shim
regression guard.
- TestToolListPeers: each diagnostic branch surfaces its reason +
explicit assertion that "may be isolated" is gone.
Coverage 91.53% (floor 86%). 122 a2a tests pass.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
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