Files
smart-support/backend/app/ws_handler.py
Yaojia Wang 1050df780d feat: complete phase 2 -- multi-agent routing, interrupt TTL, escalation, templates
- Intent classification with LLM structured output (single/multi/ambiguous)
- Discount agent with apply_discount and generate_coupon tools
- Interrupt manager with 30-min TTL auto-expiration and retry prompts
- Webhook escalation module with exponential backoff retry (max 3)
- Three vertical industry templates (e-commerce, SaaS, fintech)
- Template loading in AgentRegistry
- Enhanced supervisor prompt with dynamic agent descriptions
- 153 tests passing, 90.18% coverage
2026-03-30 21:04:39 +02:00

270 lines
9.3 KiB
Python

"""WebSocket message handling logic -- extracted from main for testability."""
from __future__ import annotations
import json
import logging
import re
from typing import TYPE_CHECKING, Any
from langchain_core.messages import HumanMessage
from langgraph.types import Command
from app.graph import classify_intent
if TYPE_CHECKING:
from fastapi import WebSocket
from langgraph.graph.state import CompiledStateGraph
from app.callbacks import TokenUsageCallbackHandler
from app.interrupt_manager import InterruptManager
from app.session_manager import SessionManager
logger = logging.getLogger(__name__)
MAX_MESSAGE_SIZE = 32_768 # 32 KB
MAX_CONTENT_LENGTH = 8_000 # characters
THREAD_ID_PATTERN = re.compile(r"^[a-zA-Z0-9\-_]{1,128}$")
async def handle_user_message(
ws: WebSocket,
graph: CompiledStateGraph,
session_manager: SessionManager,
callback_handler: TokenUsageCallbackHandler,
thread_id: str,
content: str,
interrupt_manager: InterruptManager | None = None,
) -> None:
"""Process a user message through the graph and stream results back."""
if session_manager.is_expired(thread_id):
msg = "Session expired. Please start a new conversation."
await _send_json(ws, {"type": "error", "message": msg})
return
session_manager.touch(thread_id)
# Run intent classification if available (for logging/future multi-intent)
classification = await classify_intent(graph, content)
if classification is not None:
logger.info(
"Intent classification for thread %s: ambiguous=%s, intents=%s",
thread_id,
classification.is_ambiguous,
[i.agent_name for i in classification.intents],
)
# If ambiguous, send clarification and return
if classification.is_ambiguous and classification.clarification_question:
await _send_json(
ws,
{
"type": "clarification",
"thread_id": thread_id,
"message": classification.clarification_question,
},
)
await _send_json(ws, {"type": "message_complete", "thread_id": thread_id})
return
config = {"configurable": {"thread_id": thread_id}, "callbacks": [callback_handler]}
# If multi-intent detected, add routing hint to the message
if classification and len(classification.intents) > 1:
agent_names = [i.agent_name for i in classification.intents]
hint = (
f"\n[System: This request involves multiple actions. "
f"Execute in order: {', '.join(agent_names)}]"
)
input_msg = {"messages": [HumanMessage(content=content + hint)]}
else:
input_msg = {"messages": [HumanMessage(content=content)]}
try:
async for chunk in graph.astream(input_msg, config=config, stream_mode="messages"):
msg_chunk, metadata = chunk
node = metadata.get("langgraph_node", "")
if hasattr(msg_chunk, "tool_calls") and msg_chunk.tool_calls:
for tc in msg_chunk.tool_calls:
await _send_json(
ws,
{
"type": "tool_call",
"agent": node,
"tool": tc.get("name", ""),
"args": tc.get("args", {}),
},
)
elif hasattr(msg_chunk, "content") and msg_chunk.content:
await _send_json(
ws,
{
"type": "token",
"agent": node,
"content": msg_chunk.content,
},
)
state = await graph.aget_state(config)
if _has_interrupt(state):
interrupt_data = _extract_interrupt(state)
session_manager.extend_for_interrupt(thread_id)
# Register interrupt with TTL tracking
if interrupt_manager is not None:
interrupt_manager.register(
thread_id=thread_id,
action=interrupt_data.get("action", "unknown"),
params=interrupt_data.get("params", {}),
)
await _send_json(
ws,
{
"type": "interrupt",
"thread_id": thread_id,
**interrupt_data,
},
)
else:
await _send_json(ws, {"type": "message_complete", "thread_id": thread_id})
except Exception:
logger.exception("Error processing message for thread %s", thread_id)
err = "An error occurred processing your message."
await _send_json(ws, {"type": "error", "message": err})
async def handle_interrupt_response(
ws: WebSocket,
graph: CompiledStateGraph,
session_manager: SessionManager,
callback_handler: TokenUsageCallbackHandler,
thread_id: str,
approved: bool,
interrupt_manager: InterruptManager | None = None,
) -> None:
"""Resume graph execution after interrupt approval/rejection."""
# Check interrupt TTL before resuming
if interrupt_manager is not None:
status = interrupt_manager.check_status(thread_id)
if status is not None and status.is_expired:
retry_prompt = interrupt_manager.generate_retry_prompt(status.record)
interrupt_manager.resolve(thread_id)
session_manager.resolve_interrupt(thread_id)
await _send_json(ws, retry_prompt)
return
interrupt_manager.resolve(thread_id)
session_manager.resolve_interrupt(thread_id)
session_manager.touch(thread_id)
config = {"configurable": {"thread_id": thread_id}, "callbacks": [callback_handler]}
try:
async for chunk in graph.astream(
Command(resume=approved),
config=config,
stream_mode="messages",
):
msg_chunk, metadata = chunk
node = metadata.get("langgraph_node", "")
if hasattr(msg_chunk, "content") and msg_chunk.content:
await _send_json(
ws,
{
"type": "token",
"agent": node,
"content": msg_chunk.content,
},
)
await _send_json(ws, {"type": "message_complete", "thread_id": thread_id})
except Exception:
logger.exception("Error resuming interrupt for thread %s", thread_id)
err = "An error occurred processing your response."
await _send_json(ws, {"type": "error", "message": err})
async def dispatch_message(
ws: WebSocket,
graph: CompiledStateGraph,
session_manager: SessionManager,
callback_handler: TokenUsageCallbackHandler,
raw_data: str,
interrupt_manager: InterruptManager | None = None,
) -> None:
"""Parse and route an incoming WebSocket message."""
if len(raw_data) > MAX_MESSAGE_SIZE:
await _send_json(ws, {"type": "error", "message": "Message too large"})
return
try:
data = json.loads(raw_data)
except json.JSONDecodeError:
await _send_json(ws, {"type": "error", "message": "Invalid JSON"})
return
msg_type = data.get("type")
thread_id = data.get("thread_id", "")
if not thread_id:
await _send_json(ws, {"type": "error", "message": "Missing thread_id"})
return
if not THREAD_ID_PATTERN.match(thread_id):
await _send_json(ws, {"type": "error", "message": "Invalid thread_id format"})
return
if msg_type == "message":
content = data.get("content", "")
if not content:
await _send_json(ws, {"type": "error", "message": "Missing message content"})
return
if len(content) > MAX_CONTENT_LENGTH:
await _send_json(ws, {"type": "error", "message": "Message content too long"})
return
await handle_user_message(
ws, graph, session_manager, callback_handler, thread_id, content,
interrupt_manager=interrupt_manager,
)
elif msg_type == "interrupt_response":
approved = data.get("approved", False)
await handle_interrupt_response(
ws, graph, session_manager, callback_handler, thread_id, approved,
interrupt_manager=interrupt_manager,
)
else:
await _send_json(ws, {"type": "error", "message": "Unknown message type"})
def _has_interrupt(state: Any) -> bool:
"""Check if the graph state has a pending interrupt."""
tasks = getattr(state, "tasks", ())
return any(getattr(t, "interrupts", ()) for t in tasks)
def _extract_interrupt(state: Any) -> dict:
"""Extract interrupt data from graph state."""
for task in getattr(state, "tasks", ()):
for intr in getattr(task, "interrupts", ()):
value = intr.value if hasattr(intr, "value") else {}
if not isinstance(value, dict):
value = {}
return {
"action": value.get("action", "unknown"),
"params": value,
}
return {"action": "unknown", "params": {}}
async def _send_json(ws: WebSocket, data: dict) -> None:
"""Send a JSON message through the WebSocket."""
await ws.send_json(data)