fire-planner/fire_planner/api/simulate.py
Viktor Barzin 9cc781a8d6
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fire-planner: ProjectionLab parity Wave 1 — tabbed shell, year stats, goals,
income streams, Sankey cashflow, progress overlay, settings sub-pages

Wave 1 (9 features across 4 streams):

Stream A — dashboard skeleton
  1.A.1 ScenarioShell with top tabs (Plan/Cash Flow/Tax Analytics/Compare/
        Reports/Estate/Settings) + left Sidebar with Plans switcher.
  1.A.2 GET /scenarios/{id}/year-stats?year=N returning per-year metrics
        (NW, Δ NW, taxable income, taxes, eff. rate, spending, contribs,
        investment growth). YearScrubber + YearStatsPanel render the
        right-hand sidebar; URL ?year= preserves selection.
  1.A.3 FanChart gains optional `milestones` prop (lib/milestone.ts maps
        life_event.kind → emoji) + selectedYear marker line.

Stream B — goals + progress
  1.B.1 New goals_eval module: target_nw_by_year / never_run_out /
        target_real_income probability evaluation. Wired into POST
        /simulate (exact, per-path) and GET /scenarios/{id}/projection
        (approximated from persisted fan via percentile interpolation).
        GoalsSection renders pass/fail badges.
  1.B.2 GET /scenarios/{id}/progress overlays AccountSnapshot totals on
        the projection fan; ProgressPage shows variance side-panel.

Stream C — income + cashflow
  1.C.1 New IncomeStream model + alembic 0003 + CRUD endpoints. Engine
        aggregates streams into per-year inflows + taxable arrays;
        income tax routes through the jurisdiction tax engine.
        IncomeStreamsSection on Plan tab.
  1.C.2 GET /scenarios/{id}/cashflow?year=N returns sources/sinks for
        an ECharts Sankey (sums conserve). CashflowTab body.

Stream D — settings
  1.D.1 SettingsTab + sub-nav (Milestones/Rates/Dividends/Bonds/Tax/
        Metrics/Other/Notes); placeholder cards for unbuilt sub-pages.
  1.D.2 LifeEventsSection relocated to /scenarios/:id/settings.
  1.D.3 RatesSettings (Fixed/Historical/Advanced segmented + per-asset
        cards). SimulateRequest gains rates_mode, inflation_pct,
        stocks/bonds growth + dividend, stocks_allocation. New
        build_fixed_paths() in simulator. Real-return arithmetic
        verified against (1+g+d)/(1+i)−1 ≈ 5.4%.
  1.D.4 NotesSettings — markdown textarea, save-on-blur, stored in
        scenario.config_json.notes.

Backend: 238 pytest pass (+19 new), mypy + ruff clean.
Frontend: typecheck + 7 unit tests + production build clean.

Roadmap for Wave 2-N is documented in the implementation plan.
2026-05-10 12:49:44 +00:00

246 lines
10 KiB
Python

"""Sync simulate + multi-scenario compare.
Unlike the persisted Cartesian recompute (`/recompute`), these run a
single scenario inline and return the result immediately. The React UI
uses these for what-if exploration — no DB write.
Returns a fan-chart series in the same shape as
`GET /scenarios/{id}/projection`, so frontend chart code is shared.
"""
from __future__ import annotations
import asyncio
import time
from decimal import Decimal
from pathlib import Path
import numpy as np
from fastapi import APIRouter, HTTPException
from sqlalchemy.ext.asyncio import async_sessionmaker
from fire_planner.api.schemas import (
CompareRequest,
CompareResult,
GoalProbability,
ProjectionPoint,
SimulateRequest,
SimulateResult,
)
from fire_planner.glide_path import static
from fire_planner.goals_eval import evaluate_goals
from fire_planner.income_streams import IncomeStreamInput, streams_to_arrays
from fire_planner.ingest.wealthfolio_pg import create_wf_sync_engine_from_env
from fire_planner.life_events import EventInput, events_to_cashflow_array
from fire_planner.returns.bootstrap import block_bootstrap
from fire_planner.returns.shiller import load_from_csv, synthetic_returns
from fire_planner.returns.wealthfolio_returns import (
compute_annual_returns_from_pg,
constant_real_return_paths,
)
from fire_planner.scenarios import build_regime_schedule, build_strategy
from fire_planner.simulator import SimulationResult, build_fixed_paths, simulate
router = APIRouter(tags=["simulate"])
_RETURNS_CSV = Path("/data/shiller_returns.csv")
def _shiller_paths(seed: int, n_paths: int, n_years: int) -> np.ndarray:
bundle = (load_from_csv(_RETURNS_CSV) if _RETURNS_CSV.exists() else synthetic_returns(seed=42))
rng = np.random.default_rng(seed)
return block_bootstrap(bundle, n_paths=n_paths, n_years=n_years, block_size=5, rng=rng)
async def _wealthfolio_paths(seed: int, n_paths: int, n_years: int) -> np.ndarray:
"""Block-bootstrap the user's actual blended real returns. With
typically <10 distinct annual samples, block_size=1 is appropriate
— there's no serial-correlation signal to preserve."""
eng = create_wf_sync_engine_from_env()
try:
factory = async_sessionmaker(eng, expire_on_commit=False)
async with factory() as wf_sess:
bundle = await compute_annual_returns_from_pg(wf_sess)
finally:
await eng.dispose()
rng = np.random.default_rng(seed)
return block_bootstrap(bundle, n_paths=n_paths, n_years=n_years, block_size=1, rng=rng)
async def _build_paths(req: SimulateRequest) -> np.ndarray:
if req.rates_mode == "fixed":
return build_fixed_paths(
n_paths=req.n_paths,
n_years=req.horizon_years,
inflation_pct=float(req.inflation_pct),
stocks_growth_pct=float(req.stocks_growth_pct),
stocks_dividend_pct=float(req.stocks_dividend_pct),
bonds_growth_pct=float(req.bonds_growth_pct),
bonds_dividend_pct=float(req.bonds_dividend_pct),
)
if req.returns_mode == "manual":
if req.manual_real_return_pct is None:
raise HTTPException(
status_code=400,
detail="manual_real_return_pct is required when returns_mode='manual'",
)
return constant_real_return_paths(
n_paths=req.n_paths,
n_years=req.horizon_years,
real_return_pct=float(req.manual_real_return_pct),
)
if req.returns_mode == "wealthfolio":
try:
return await _wealthfolio_paths(req.seed, req.n_paths, req.horizon_years)
except ValueError as e:
raise HTTPException(
status_code=400,
detail=f"Wealthfolio history insufficient: {e}",
) from e
return _shiller_paths(req.seed, req.n_paths, req.horizon_years)
def _project(req: SimulateRequest, paths: np.ndarray) -> tuple[SimulationResult, float]:
annual_savings = (np.full(req.horizon_years, float(req.savings_per_year_gbp), dtype=np.float64)
if req.savings_per_year_gbp > 0 else None)
floor = float(req.floor_gbp) if req.floor_gbp is not None else None
cashflow_adjustments = None
if req.life_events:
engine_events = [
EventInput(
year_start=ev.year_start,
year_end=ev.year_end,
delta_gbp_per_year=float(ev.delta_gbp_per_year),
one_time_amount_gbp=(float(ev.one_time_amount_gbp)
if ev.one_time_amount_gbp is not None else None),
enabled=ev.enabled,
) for ev in req.life_events
]
cashflow_adjustments = events_to_cashflow_array(engine_events, req.horizon_years)
income_inflows = None
income_taxable = None
if req.income_streams:
engine_streams = [
IncomeStreamInput(
kind=s.kind,
start_year=s.start_year,
end_year=s.end_year,
amount_gbp_per_year=float(s.amount_gbp_per_year),
growth_pct=float(s.growth_pct),
tax_treatment=s.tax_treatment,
enabled=s.enabled,
) for s in req.income_streams
]
income_inflows, income_taxable = streams_to_arrays(engine_streams, req.horizon_years)
strategy = build_strategy(
req.strategy,
floor=floor,
annual_real_adjust_pct=float(req.annual_real_adjust_pct),
guardrail_threshold_pct=(float(req.guardrail_threshold_pct)
if req.guardrail_threshold_pct is not None else None),
guardrail_cut_pct=float(req.guardrail_cut_pct),
)
glide_alloc = float(req.stocks_allocation) if req.rates_mode == "fixed" else 1.0
started = time.perf_counter()
result = simulate(
paths=paths,
initial_portfolio=float(req.nw_seed_gbp),
spending_target=float(req.spending_gbp),
glide=static(glide_alloc),
strategy=strategy,
regime=build_regime_schedule(req.jurisdiction, req.leave_uk_year),
horizon_years=req.horizon_years,
annual_savings=annual_savings,
cashflow_adjustments=cashflow_adjustments,
income_inflows=income_inflows,
income_taxable=income_taxable,
)
elapsed = time.perf_counter() - started
return result, elapsed
def _to_response(
result: SimulationResult,
elapsed: float,
req: SimulateRequest | None = None,
) -> SimulateResult:
# portfolio_real has n_years+1 columns (year 0 = seed, year k = end-of-year k).
# withdrawal_real / tax_real have n_years columns (year k = withdrawn in year k+1).
# Yearly point k describes "end of year k+1": portfolio after withdrawal & growth.
pcts = [10, 25, 50, 75, 90]
portfolio_quantiles = {p: np.percentile(result.portfolio_real, p, axis=0) for p in pcts}
median_wd = np.percentile(result.withdrawal_real, 50, axis=0)
median_tax = np.percentile(result.tax_real, 50, axis=0)
n_years = result.n_years
survival_path = (result.success_mask.astype(np.float64).mean(axis=0) if
result.success_mask.ndim == 2 else np.ones(n_years))
yearly = [
ProjectionPoint(
year_idx=y,
p10_portfolio_gbp=Decimal(str(round(float(portfolio_quantiles[10][y + 1]), 2))),
p25_portfolio_gbp=Decimal(str(round(float(portfolio_quantiles[25][y + 1]), 2))),
p50_portfolio_gbp=Decimal(str(round(float(portfolio_quantiles[50][y + 1]), 2))),
p75_portfolio_gbp=Decimal(str(round(float(portfolio_quantiles[75][y + 1]), 2))),
p90_portfolio_gbp=Decimal(str(round(float(portfolio_quantiles[90][y + 1]), 2))),
p50_withdrawal_gbp=Decimal(str(round(float(median_wd[y]), 2))),
p50_tax_gbp=Decimal(str(round(float(median_tax[y]), 2))),
survival_rate=Decimal(str(round(float(survival_path[y]), 4))),
) for y in range(n_years)
]
median_ytr = result.median_years_to_ruin()
goals_probability: list[GoalProbability] = []
if req is not None and req.goals:
evaluations = evaluate_goals(result, req.goals, req.horizon_years)
goals_probability = [
GoalProbability(
goal_id=None,
name=ev.name,
kind=ev.kind,
probability=Decimal(str(round(ev.probability, 4))),
threshold=Decimal(str(round(ev.threshold, 4))),
passed=ev.passed,
) for ev in evaluations
]
return SimulateResult(
success_rate=Decimal(str(round(float(result.success_rate), 4))),
p10_ending_gbp=Decimal(str(round(float(result.ending_percentile(10)), 2))),
p50_ending_gbp=Decimal(str(round(float(result.ending_percentile(50)), 2))),
p90_ending_gbp=Decimal(str(round(float(result.ending_percentile(90)), 2))),
median_lifetime_tax_gbp=Decimal(str(round(float(result.median_lifetime_tax()), 2))),
median_years_to_ruin=(Decimal(str(round(float(median_ytr), 2)))
if median_ytr is not None else None),
elapsed_seconds=Decimal(str(round(elapsed, 3))),
yearly=yearly,
goals_probability=goals_probability,
)
@router.post("/simulate", response_model=SimulateResult)
async def simulate_one(req: SimulateRequest) -> SimulateResult:
"""Run one scenario synchronously, no DB write. ~1-3s for 5k paths."""
paths = await _build_paths(req)
try:
result, elapsed = await asyncio.to_thread(_project, req, paths)
except KeyError as e:
raise HTTPException(status_code=400, detail=f"Unknown name: {e}") from None
return _to_response(result, elapsed, req)
@router.post("/compare", response_model=CompareResult)
async def compare_scenarios(req: CompareRequest) -> CompareResult:
"""Run 2-5 scenarios in parallel, return all results."""
async def one(s: SimulateRequest) -> SimulateResult:
paths = await _build_paths(s)
result, elapsed = await asyncio.to_thread(_project, s, paths)
return _to_response(result, elapsed, s)
try:
results = await asyncio.gather(*(one(s) for s in req.scenarios))
except KeyError as e:
raise HTTPException(status_code=400, detail=f"Unknown name: {e}") from None
return CompareResult(results=results)