Files
nvi/api/runtime/runner.py

204 lines
7.2 KiB
Python

"""langgraph wiring — the one place the framework appears.
Graph: START → plan → execute → synthesize → END
`execute` iterates Plan steps and dispatches each to its Analysis. A step
can declare an optional `fallback` Analysis that runs when the primary
errors or returns an empty finding.
"""
from __future__ import annotations
import dataclasses
import logging
from typing import Any
from langgraph.graph import END, START, StateGraph
from api import langfuse_client as lf
from api.analyses.registry import REGISTRY as ANALYSES
from api.analyses.types import Finding
from api.llm import chat
from api.plan.planner import plan as run_planner
from api.prompts import load, render
from api.runtime import events
from api.runtime.context import current_analysis, current_run_id
from api.runtime.state import RunState
logger = logging.getLogger("nvi.runtime")
def _plan_node(state: RunState) -> dict[str, Any]:
plan_obj = run_planner(state["question"])
return {
"plan_rationale": plan_obj.rationale,
"plan_steps": [s.to_dict() for s in plan_obj.steps],
}
def _step_id(idx: int, name: str, suffix: str | None = None) -> str:
base = f"{name}#{idx}"
return f"{base}.{suffix}" if suffix else base
async def _invoke_analysis(name: str, args: dict[str, Any], question: str,
*, step_id: str, run_id: str, why: str) -> Finding:
"""Run a single Analysis with contextvar set, events around it, and
error→Finding catch. Returns the Finding (success or failure)."""
analysis = ANALYSES.get(name)
await events.publish(run_id, events.analysis_start(name, args, why, step_id=step_id))
if analysis is None:
f = Finding(analysis=name, summary="", error=f"unknown analysis {name!r}")
else:
token = current_analysis.set(step_id)
try:
f = await analysis.run(args, question)
except Exception as e:
logger.exception("analysis %s raised", name)
f = Finding(analysis=name, summary="", error=str(e))
finally:
current_analysis.reset(token)
await events.publish(run_id, events.analysis_end(name, f, step_id=step_id))
return f
def _finding_is_empty_or_errored(f: Finding) -> bool:
if f.error:
return True
if not f.summary and not f.rows:
return True
return False
async def _execute_node(state: RunState) -> dict[str, Any]:
findings: list[dict[str, Any]] = []
run_id = state["run_id"]
for idx, step in enumerate(state.get("plan_steps", [])):
primary_name = step["analysis"]
primary_args = step.get("args", {})
primary_why = step.get("why", "")
primary_step_id = _step_id(idx, primary_name)
primary = await _invoke_analysis(
primary_name, primary_args, state["question"],
step_id=primary_step_id, run_id=run_id, why=primary_why,
)
primary_dict = dataclasses.asdict(primary)
primary_dict["step_id"] = primary_step_id
findings.append(primary_dict)
fb = step.get("fallback")
if fb and _finding_is_empty_or_errored(primary):
fb_name = fb["analysis"]
fb_step_id = _step_id(idx, fb_name, suffix="fallback")
reason = primary.error or "primary returned empty finding"
await events.publish(run_id, events.analysis_fallback(
primary=primary_name, fallback=fb_name, reason=reason,
step_id=fb_step_id,
))
fb_finding = await _invoke_analysis(
fb_name, fb.get("args", {}), state["question"],
step_id=fb_step_id, run_id=run_id, why=fb.get("why", ""),
)
fb_dict = dataclasses.asdict(fb_finding)
fb_dict["step_id"] = fb_step_id
fb_dict["is_fallback_for"] = primary_step_id
findings.append(fb_dict)
return {"findings": findings}
async def _synthesize_node(state: RunState) -> dict[str, Any]:
await events.publish(state["run_id"], events.synth_start())
findings = state.get("findings", [])
# Effective findings = primary OR its fallback if the primary was empty.
# Pass everything through; the LLM weighs which one to cite.
usable = [f for f in findings if not _finding_is_empty_or_errored(_dict_to_finding(f))]
if not usable:
return {
"answer": "I couldn't answer this question — see the per-analysis errors above.",
"error": "all_analyses_failed",
}
findings_block = "\n\n".join(
f"[{f['analysis']}{ ' (fallback)' if f.get('is_fallback_for') else '' }]\n"
f"summary: {f.get('summary') or '(none)'}\n"
f"error: {f.get('error') or '(none)'}\n"
f"sql: {f.get('sql')}"
for f in findings
)
with lf.span("synthesize", as_type="generation", input={"findings": len(findings)}) as span:
answer = chat(
system=load("synthesize.system"),
user=render(
"synthesize.user",
question=state["question"],
findings_block=findings_block,
),
max_tokens=512,
)
span.update(output={"answer": answer})
return {"answer": answer}
def _dict_to_finding(d: dict[str, Any]) -> Finding:
return Finding(
analysis=d.get("analysis", ""),
summary=d.get("summary", ""),
rows=d.get("rows") or [],
sql=d.get("sql") or [],
error=d.get("error"),
metadata=d.get("metadata") or {},
)
def build_graph():
g: StateGraph = StateGraph(RunState)
g.add_node("plan", _plan_node)
g.add_node("execute", _execute_node)
g.add_node("synthesize", _synthesize_node)
g.add_edge(START, "plan")
g.add_edge("plan", "execute")
g.add_edge("execute", "synthesize")
g.add_edge("synthesize", END)
return g.compile()
GRAPH = build_graph()
async def run(run_id: str, question: str) -> RunState:
"""Drive the graph end-to-end, publishing SSE events along the way."""
initial: RunState = {"run_id": run_id, "question": question}
final: RunState = initial
token = current_run_id.set(run_id)
try:
await events.publish(run_id, events.run_start(question))
async for event in GRAPH.astream(initial, stream_mode="updates"):
for node, update in event.items():
await events.publish(run_id, events.node_update(node, update))
if isinstance(update, dict):
final = {**final, **update}
if node == "plan" and isinstance(update, dict):
await events.publish(
run_id,
events.plan_ready(
update.get("plan_rationale", ""),
update.get("plan_steps", []),
),
)
await events.publish(
run_id,
events.run_end(answer=final.get("answer", ""), error=final.get("error")),
)
except Exception as e:
logger.exception("run %s failed", run_id)
await events.publish(run_id, events.run_end(error=str(e)))
final = {**final, "error": str(e)}
finally:
current_run_id.reset(token)
await events.close(run_id)
lf.flush()
return final