"""A2A client tools (``a2a`` toolset): a2a_discover/call/list/history/orchestrate talk to *other* agents. Peers come from config.yaml ``a2a_agents: {name: {url, auth: {type: bearer, token}, timeout, capabilities}}``. Stdlib urllib; wire format is A2A v1.0 ``SendMessage`` (v0.3 replies still parse).""" from __future__ import annotations import contextlib import json import logging import urllib.error import urllib.request from concurrent.futures import ThreadPoolExecutor, as_completed from typing import Any, Optional from gateway.platforms._shared import coerce_port as _coerce_int, get_scoped_secret as _get_scoped_secret from . import protocol, security logger = logging.getLogger(__name__) _DEFAULT_TIMEOUT = 120 _ORCHESTRATE_MAX_WORKERS = 6 # max parallel peers for fan-out def _load_config() -> dict: """Read-only view of config.yaml; peers are only read, never mutated (cache-safe).""" from hermes_cli.config import load_config_readonly return load_config_readonly() or {} def _configured_peers() -> dict: return _load_config().get("a2a_agents") or {} def _peer_from_entry(entry: dict, **extra: Any) -> dict: return {"url": entry.get("url", ""), "auth": entry.get("auth", {}) or {}, "timeout": int(entry.get("timeout", _DEFAULT_TIMEOUT)), **extra} def _resolve_peer(agent: str) -> Optional[dict]: """Peer name -> {url, auth, timeout, capabilities, tenant}, or treat ``agent`` as a URL.""" if agent.startswith(("http://", "https://")): return {"url": agent, "auth": {}, "timeout": _DEFAULT_TIMEOUT, "capabilities": []} entry = _configured_peers().get(agent) return _peer_from_entry(entry, capabilities=entry.get("capabilities", []) or [], tenant=entry.get("tenant", "")) if entry else None def _auth_header(auth: dict) -> dict: return {"Authorization": f"Bearer {auth['token']}"} if auth and auth.get("type") == "bearer" and auth.get("token") else {} def _http_json(url: str, headers: dict, timeout: int, method: str, data: Optional[bytes] = None) -> dict: req = urllib.request.Request(url, data=data, headers=headers, method=method) with urllib.request.urlopen(req, timeout=timeout) as resp: # noqa: S310 (configured peers) return json.loads(resp.read().decode("utf-8")) def _http_get_json(url: str, headers: dict, timeout: int) -> dict: return _http_json(url, headers, timeout, "GET") def _http_post_json(url: str, body: dict, headers: dict, timeout: int) -> dict: hdrs = {"Content-Type": "application/json", "A2A-Version": protocol.PROTOCOL_VERSION, **headers} return _http_json(url, hdrs, timeout, "POST", json.dumps(body).encode("utf-8")) def _fetch_card(base_url: str, headers: dict, timeout: int) -> dict: """GET the v1.0 agent-card.json; on 404 fall back to the v0.2 agent.json alias.""" base = base_url.rstrip("/") try: return _http_get_json(base + "/.well-known/agent-card.json", headers, timeout) except urllib.error.HTTPError as e: if e.code != 404: raise return _http_get_json(base + "/.well-known/agent.json", headers, timeout) def _select_jsonrpc_interface(card: Optional[dict]) -> Optional[dict]: if isinstance(card, dict): for iface in card.get("supportedInterfaces", []) or []: if isinstance(iface, dict) and iface.get("protocolBinding") == "JSONRPC" and iface.get("url"): return iface return None def _rpc_url(base_url: str, card: Optional[dict]) -> str: """Card's JSONRPC interface (v1.0 supportedInterfaces) > card's legacy top-level url > base.""" if iface := _select_jsonrpc_interface(card): return str(iface["url"]) if isinstance(card, dict) and isinstance(card.get("url"), str) and card["url"]: return card["url"] return base_url.rstrip("/") def _send_task(agent_label: str, peer: dict, message: str, context_id: str) -> tuple[str, str, str]: """One SendMessage to a peer -> (reply_text, context_id, state). Raises urllib errors / ValueError for the caller to format; handles redaction, audit, persistence, metrics.""" base_url = peer.get("url", "") headers = _auth_header(peer.get("auth", {}) or {}) timeout = int(peer.get("timeout", _DEFAULT_TIMEOUT)) try: card = _fetch_card(base_url, headers, min(timeout, 30)) # best-effort, to learn the rpc URL except Exception: card = None ctx = context_id or protocol.new_context_id() safe_message = security.redact_outbound(message) # v1.0: contextId lives inside the Message, not at the params top level. rpc_body = {"jsonrpc": "2.0", "id": protocol.new_task_id(), "method": "SendMessage", "params": {"message": protocol.text_message(protocol.ROLE_USER, safe_message, context_id=ctx)}} iface = _select_jsonrpc_interface(card) tenant = str(iface["tenant"]) if iface and iface.get("tenant") else str(peer.get("tenant") or "") if tenant: rpc_body["params"]["tenant"] = tenant security.audit("outbound", agent_label, rpc_body["id"], safe_message) protocol.persist_message(ctx, "user", safe_message, rpc_body["id"]) protocol.metrics.outbound_total += 1 resp = _http_post_json(_rpc_url(base_url, card), rpc_body, headers, timeout) if "error" in resp: raise ValueError(f"Peer '{agent_label}' returned an error: {resp['error'].get('message', resp['error'])}") payload = protocol.unwrap_send_message_response(resp.get("result", {})) reply = _reply_text_from_result(payload) reply_ctx, state = ctx, "" if isinstance(payload, dict): reply_ctx = payload.get("contextId", ctx) state = (payload.get("status") or {}).get("state", "") protocol.persist_message(reply_ctx, "agent", reply, rpc_body["id"]) protocol.metrics.inbound_total += 1 return reply, reply_ctx, state def _reply_text_from_result(result: Any) -> str: result = protocol.unwrap_send_message_response(result) if not isinstance(result, dict): return str(result) # Artifacts first (final output), then status message (interim/clarify), else bare Message. for artifact in result.get("artifacts", []) or []: txt = protocol.extract_text(artifact) if txt: return txt return protocol.extract_text((result.get("status", {}) or {}).get("message") or result) _AUTH_ERR = "Error: peer '{agent}' rejected auth (HTTP {code}). Check the configured token." _HTTP_CALL_ERRORS = {401: _AUTH_ERR, 403: _AUTH_ERR, 429: "Error: peer '{agent}' rate limited us (HTTP 429). Retry later."} def a2a_discover(args: dict, **_: Any) -> str: """Fetch and summarize the Agent Card at ``url``.""" url = str(args.get("url") or "").strip() if not url: return "Error: 'url' is required (e.g. http://localhost:9999)." try: card = _fetch_card(url, {}, _DEFAULT_TIMEOUT) except urllib.error.HTTPError as e: return f"Error: discovery failed — HTTP {e.code} from {url}." except Exception as e: return f"Error: could not reach {url} — {e}." caps = card.get("capabilities", {}) or {} skills = card.get("skills", []) or [] auth = "yes" if card.get("security") else "no" proto = ", ".join( f"{i.get('protocolBinding', '?')} v{i.get('protocolVersion', '?')}" for i in (card.get("supportedInterfaces", []) or []) if isinstance(i, dict) ) or f"v{card.get('protocolVersion', '?')} (pre-1.0 card)" lines = [f"Agent: {card.get('name', '?')}", f"Description: {card.get('description', '')}", f"URL: {_rpc_url(url, card)}", f"Protocol: {proto}", f"Streaming: {bool(caps.get('streaming'))} Push: {bool(caps.get('pushNotifications'))} Auth required: {auth}", f"Skills ({len(skills)}):"] lines.extend(f" - {s.get('name', s.get('id', '?'))}: {s.get('description', '')}" for s in skills[:20]) return "\n".join(lines) def a2a_call(args: dict, **_: Any) -> str: """Send a task to a peer (configured name or direct URL); ``context_id`` continues a prior exchange.""" # Accept common aliases models reach for (observed live: 'agent_name'). agent = str(args.get("agent") or args.get("agent_name") or args.get("name") or "").strip() message = str(args.get("message") or args.get("text") or args.get("task") or "").strip() context_id = str(args.get("context_id") or args.get("contextId") or "").strip() if not agent or not message: return "Error: both 'agent' and 'message' are required." peer = _resolve_peer(agent) if not peer or not peer.get("url"): return f"Error: unknown agent '{agent}'. Configure it under 'a2a_agents' in config.yaml or pass a full http(s):// URL." try: reply, reply_ctx, state = _send_task(agent, peer, message, context_id) except urllib.error.HTTPError as e: return _HTTP_CALL_ERRORS.get(e.code, "Error: call to '{agent}' failed — HTTP {code}.").format(agent=agent, code=e.code) except ValueError as e: return str(e) except Exception as e: return f"Error: call to '{agent}' failed — {e}." short_state = state.replace("TASK_STATE_", "").replace("_", "-").lower() # v0.3 states pass through header = f"[{agent} · context {reply_ctx}" + (f" · {short_state}" if state else "") + "]" body = reply or "(no text reply)" if state == protocol.STATE_INPUT_REQUIRED: body += f"\n\n(The peer needs more input — answer by calling a2a_call again with context_id '{reply_ctx}'.)" return f"{header}\n{body}" def a2a_list(args: dict | None = None, **_: Any) -> str: """List configured A2A peers, persisted conversations, and metrics.""" peers = _configured_peers() lines = [] if peers: lines.append(f"Configured peers ({len(peers)}):") for name, entry in peers.items(): caps = entry.get("capabilities", []) lines.append(f" - {name}: {entry.get('url', '?')} (auth: {(entry.get('auth') or {}).get('type', 'none')})" + (f" caps: {', '.join(caps)}" if caps else "")) else: lines.append("No peers configured. Add them under 'a2a_agents' in config.yaml.") if convos := protocol.list_conversations(): lines.append("") lines.append(f"Persisted conversations ({len(convos)}) — recall with a2a_history:") lines.extend(f" - {c}" for c in convos[:25]) m = protocol.metrics.snapshot() lines.append("") lines.append(f"Metrics: {m['inbound_total']} in / {m['outbound_total']} out, {m['tasks_completed']} completed, " f"{m['tasks_failed']} failed, {m['streams_started']} streams, {m['push_sent']} push sent, " f"{m['anti_loop_triggers']} anti-loop, {m['rate_limit_triggers']} rate-limited, avg {m['avg_latency_ms']}ms") return "\n".join(lines) def a2a_history(args: dict, **_: Any) -> str: """Recall a persisted A2A conversation (survives compaction/restarts).""" context_id = str(args.get("context_id") or args.get("contextId") or "").strip() if not context_id: return "Error: 'context_id' is required (see a2a_list for known conversations)." limit = max(1, min(_coerce_int(args.get("limit") or 50, 50), 200)) messages = protocol.load_conversation(context_id, limit=limit) if not messages: return f"No persisted conversation for context '{context_id}'." lines = [f"Conversation {context_id} (last {len(messages)} messages):"] for m in messages: text = (m.get("text") or "").strip() lines.append(f"[{m.get('role', '?')}] {text[:1000] + ' …[truncated]' if len(text) > 1000 else text}") return "\n".join(lines) def _match_peers_by_capability(capability: str) -> list[tuple[str, dict]]: """Configured peers that advertise the capability ('*' matches all).""" return [(name, entry) for name, entry in _configured_peers().items() if capability in (entry.get("capabilities", []) or []) or capability == "*"] def _call_peer_sync(agent_name: str, peer_entry: dict, message: str, context_id: str = "") -> tuple[str, str]: """Call a single peer synchronously -> (agent_name, reply_text).""" try: reply, _ctx, _state = _send_task(agent_name, _peer_from_entry(peer_entry), message, context_id) return (agent_name, reply or "(no reply)") except Exception as e: return (agent_name, f"Error: {e}") def a2a_orchestrate(args: dict, **_: Any) -> str: """Fan-out a task to peers matching a capability. Modes: ``all``, ``first`` (first successful), ``best`` (longest successful — coarse; use ``all`` to judge yourself).""" capability = str(args.get("capability") or "").strip() message = str(args.get("message") or args.get("task") or "").strip() mode = str(args.get("mode") or "all").strip().lower() mode = mode if mode in ("all", "first", "best") else "all" context_id = str(args.get("context_id") or "").strip() if not message: return "Error: 'message' is required." if not capability: return "Error: 'capability' is required (or use '*' for all peers)." if not (matches := _match_peers_by_capability(capability)): return f"Error: no configured peers advertise capability '{capability}'." results: list[tuple[str, str]] = [] with ThreadPoolExecutor(max_workers=min(len(matches), _ORCHESTRATE_MAX_WORKERS)) as pool: futures = {pool.submit(_call_peer_sync, name, entry, message, context_id): name for name, entry in matches} for fut in as_completed(futures): name = futures[fut] try: results.append(fut.result()) if mode == "first" and not results[-1][1].startswith("Error:"): for f in futures: # good reply; cancel peers that haven't started f.cancel() break except Exception as e: results.append((name, f"Error: {e}")) results.sort(key=lambda r: r[0]) # deterministic output successes = [(name, reply) for name, reply in results if not reply.startswith("Error:")] if mode in ("best", "first"): if not successes: return "\n".join(["All peers failed:"] + [f" {name}: {reply}" for name, reply in results]) name, reply = max(successes, key=lambda r: len(r[1])) if mode == "best" else successes[0] return f"[{mode}: {name}]\n{reply}" return "\n".join([f"Orchestrated '{capability}' to {len(matches)} peer(s):"] + [line for name, reply in results for line in (f"\n--- {name} ---", reply)]) def _str(description: str) -> dict: return {"type": "string", "description": description} # name -> (handler, description, properties, required) _TOOLS: dict[str, tuple[Any, str, dict, list[str]]] = { "a2a_discover": (a2a_discover, "Fetch and summarize another agent's A2A Agent Card from a URL (its name, description, " "capabilities, and skills). Use this to find out what a remote agent can do before calling it.", {"url": _str("Base URL of the remote A2A agent, e.g. http://localhost:9999")}, ["url"]), "a2a_call": (a2a_call, "Send a natural-language task to a remote A2A agent and return its reply. The agent is a peer " "(any A2A-compliant framework), not a sub-agent you control. Pass 'context_id' from a previous " "reply to continue a multi-turn exchange.", {"agent": _str("Configured peer name (from a2a_agents) or a full http(s):// URL."), "message": _str("The task / message to send the peer, in natural language."), "context_id": _str("Optional: context id from a prior reply, to continue the conversation.")}, ["agent", "message"]), "a2a_list": (a2a_list, "List configured A2A peer agents, persisted A2A conversations, and metrics.", {}, []), "a2a_history": (a2a_history, "Recall a persisted A2A conversation transcript by context_id (survives restarts and " "context compaction). Use a2a_list to see known context ids.", {"context_id": _str("Context id of the conversation to recall."), "limit": {"type": "integer", "description": "Max messages to return (default 50, max 200)."}}, ["context_id"]), "a2a_orchestrate": (a2a_orchestrate, "Fan-out a task to multiple peer agents by capability. Peers are matched from config.yaml " "a2a_agents.*.capabilities. Modes: 'all' (return all replies), 'first' (first successful), " "'best' (longest successful reply).", {"capability": _str("Capability to match (e.g. 'research', 'code') or '*' for all peers."), "message": _str("The task to send to all matching peers."), "mode": {"type": "string", "enum": ["all", "first", "best"], "description": "How to aggregate results. Default: 'all'."}, "context_id": _str("Optional: shared context id for all peers.")}, ["capability", "message"]), } def _a2a_tools_available() -> bool: """check_fn: serve the client tools ONLY when the operator opted into A2A (peers under ``a2a_agents``, inbound platform enabled, or A2A_PORT set). Fail closed. Maintainer-directed (#95681): these registered unconditionally, so every session on every install paid ~561 tok/call for tools whose only possible output without config is 'no peers configured'. A2A is unrelated to Bot Mode (bots talk over gateway RPCs) — for most installs this toolset is foreign-agent plumbing they never enabled. Config adds mid-session surface at the next compaction (#97073). """ cfg = {} with contextlib.suppress(Exception): cfg = _load_config() if cfg.get("a2a_agents"): return True try: # Scoped like the platform gate: os.environ is the launch profile's under multiplexing (#122126). if _get_scoped_secret("A2A_PORT"): return True a2a_cfg = (cfg.get("platforms") or {}).get("a2a") or {} return bool(isinstance(a2a_cfg, dict) and a2a_cfg.get("enabled")) except Exception: # noqa: BLE001 return False def register_tools(ctx) -> None: """Register the client tools in the ``a2a`` toolset (config-gated).""" for name, (handler, description, properties, required) in _TOOLS.items(): parameters: dict[str, Any] = {"type": "object", "properties": properties} if required: parameters["required"] = required ctx.register_tool(name=name, toolset="a2a", handler=handler, description=description, schema={"name": name, "description": description, "parameters": parameters}, emoji="\U0001f9e9", check_fn=_a2a_tools_available) # puzzle piece