When a peer_agent push lands and the agent needs context from prior
turns with that workspace ("what task did this peer assign me last
hour?", "what did I tell them?"), the only options today are
re-deriving from memory (lossy) or scrolling activity_logs in the
canvas (no agent-facing tool). Surface the platform's existing
audit log directly via a new MCP tool so agents can read both sides
of an A2A conversation in chronological order.
Implementation:
- a2a_tools.py: new tool_chat_history(peer_id, limit=20, before_ts="")
hits /workspaces/<self>/activity?peer_id=X&limit=N (the new server
filter from molecule-core#2472). Reverses the DESC response into
chronological order so the agent reads top-down. Graceful error
envelope on validation/network/non-200 — never crashes the MCP
server, agent can branch on Error: prefix.
- platform_tools/registry.py: ToolSpec wired into the A2A section so
the rendered system-prompt block automatically includes it. Same
pattern as the existing inbox_peek/inbox_pop/wait_for_message.
- a2a_mcp_server.py: dispatch in handle_tool_call.
- executor_helpers.py: _CLI_A2A_COMMAND_KEYWORDS gets a None entry
(CLI runtimes don't expose chat history today; flip to a keyword
when a2a_cli grows a `history` subcommand).
- snapshots/a2a_instructions_mcp.txt regenerated.
Tests: 10 new branches in TestChatHistory (validation / param
forwarding / limit cap / before_ts pass-through / DESC→chronological
reorder / 400 verbatim / 500 generic / network exc / non-list resp).
Mutation-verified: reverting a2a_tools.py fails 10/10. Full test
suite remains green at 1516 passed.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
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