Build a Public Project Cost-Benefit and Timing Review Workbench — Implementation planning and evidence-linked development

## User
A public-sector analyst comparing infrastructure proposals.

## Build
Compare fictional public projects using transparent timing, cost, and benefit assumptions. Keep distributional effects and unpriced impacts visible beside the present-value calculation.

## Input Contract
- Key: project_id + scenario_id + year + flow_type.
- Fields: amount, real_or_nominal, price_year, beneficiary_group, discount_rate, evidence_quality.
- Do not discount nominal flows using an unexplained real rate. Separate transfers from resource costs.

## Workflow
1. Reconcile flows and economic accounting boundaries.
2. Calculate present values under stated timing and rate assumptions.
3. Compare distributional and unpriced effects separately.
4. Export a ranked scenario report with switching-value sensitivities.

## Interface
A project comparison table with cash-flow timelines, distribution panels, and assumption sensitivity controls.

## Deliverables
- A transparent project appraisal workbook.
- A decision memo with unpriced impacts and uncertainty rather than one unsupported ranking.
- Runnable local application, setup commands, and a dependency lockfile.
- Versioned input data, data dictionary, acquisition instructions, and rights notes.
- Calculation traces, source references, assumption records, and exported review artifacts.
- A deterministic baseline and tests for normal, incomplete, contradictory, and failure-recovery cases.
- A recorded complete workflow with a reproducible manifest and explicit limitations.

## Acceptance Criteria
- Discounting follows the stated time-zero convention.
- Price basis and discount basis are compatible.
- Transfers are not counted as both a benefit and a net resource gain without justification.
- A positive present value is not labeled automatic policy approval.

## Contrast Case
Identical future benefits can reverse a project ranking when timing differs. The fixture isolates the stated discount convention.

## Dataset Scope
The attached starter files are prototype inputs. Expected starter answers are visible. They are not independent holdouts.

Full target: Author three fictional projects with annual costs, benefits, maintenance, uncertainty scenarios, and beneficiary groups. Supply discount assumptions instead of claiming a mandated rate.

Complete target contracts and expert review remain pending. Public observations are not historical release vintages.

## Tools
NumPy, pandas, openpyxl

Use an available model appropriate to the task. Record provider, model identifier, version or retrieval date, settings, cost, and latency. Use deterministic code for calculations. Models may extract, retrieve, or explain evidence. They must not invent missing records, override approval rules, or claim professional authority.

## Constraints
No discount rate in the fixtures is a current government requirement.

- No fabricated records, source citations, professional endorsements, or expert-adjudication claims.
- No future-data leakage into dated decisions, model fitting, or historical valuation inputs.
- No unauthorized payments, account restrictions, regulatory filings, or production changes.
- No automated appraisal certification, tax-compliance determination, or unsupported fraud accusation.
- No concealed uncertainty or silently invented inputs required for a numerical conclusion.

## Scoring
- Correct domain calculations and justified methods with documented assumptions. Weight: 30.
- Source lineage, temporal integrity, rights checks, and explicit synthetic-data labels. Weight: 25.
- A working application with review, export, error handling, and reproducible state. Weight: 20.
- Adversarial cases, uncertainty, missing-data behavior, and sensitivity analysis. Weight: 15.
- Evidence-linked conclusions that distinguish facts, assumptions, and unresolved judgments. Weight: 10.
Score each dimension from zero to two. Weighted score = sum(weight * score / 2). A failed safety gate blocks acceptance.