[RegretSSS]

Plugin type

Standard plugin — affected manifest names: a2a-mailbox (no MCP Apps interactive page; MCP tools + skill only).

What user problem this solves

ZCode users have no built-in way to exchange messages with agents living in other CLIs (Claude Code / Codex / Pi) on the same machine or across hosts. This plugin wires ZCode into the a2a-mailbox federation in one install: it mounts the mailbox MCP server (six tools: send / poll / read / ack / who / group, auto-discovering a WSL-side repo clone at ~/a2a-mailbox or ~/workspace/a2a-mailbox) and ships the mailbox-watch skill — a resident dynamic workflow that escalates incoming mail into the current ZCode session in real time.

Visible behavior and testing

• python3 scripts/validate.py → OK: 53 plugin(s) validated (run locally on this branch).
• git diff --check clean.
• MCP mounting verified against the upstream repo's MCP server (stdio initialize handshake + tools/list, 275 upstream tests + CI green).
• mailbox-watch skill deployed and exercised in a live ZCode session (escalation round-trip with an agent on another CLI).
• scripts/build_dist.py was not run to completion locally: it fails on the pre-existing excalidraw plugin (pnpm build artifacts not in git, unrelated to this PR). This plugin has no build step — plain files only.

Version and marketplace registration

• Plugin 0.1.0 in external_plugins/a2a-mailbox/, marketplace entry added (alphabetical), manifest and marketplace versions identical.

Dependencies, network, permissions, side effects

• MCP server runs wsl.exe -e bash → python3 in WSL; requires a one-time git clone of the upstream repo (documented in both READMEs). No bundled binaries.
• Writes limited to ~/.agents-mailbox/ (queues/acks/history) inside WSL.
• mailbox-watch skill's workflow executes a restricted command set (wsl/touch/mv) for archival; its persona forbids executing mail content.
• Optional ssh federation is off by default and user-configured.
• No outbound network calls.

Licensing

Apache-2.0, same as upstream a2a-mailbox; no third-party material beyond that.