---
title: "Right-Wing Party Axis Validation"
type: feat
status: completed
date: 2026-04-05
origin: docs/brainstorms/2026-04-05-right-wing-party-axis-validation-requirements.md
---

# Right-Wing Party Axis Validation

## Overview

Add automated tests that assert PVV, FVD, JA21, and SGP appear on the RIGHT side of the political compass (mean-based), using real DuckDB data. Consolidate the conflicting `RIGHT_PARTIES`/`LEFT_PARTIES` inline definitions into `analysis/config.py`.

## Problem Frame

The AGENTS.md convention states that PVV, FVD, JA21, and SGP must appear on the RIGHT side of all axes. Three files define conflicting party sets: `svd_labels.py` has 9 right parties, `political_axis.py` has 6, and neither matches the convention. No automated validation exists.

## Requirements Trace

- R1. Canonical party sets defined once, imported everywhere
- R2. Validation test loads real data from DuckDB
- R3. 2D political compass orientation check (statistical, mean-based)
- R4. `compute_flip_direction` consistency check
- R5. Clear failure messages

## Scope Boundaries

- Only aligned scores validated (not unaligned)
- Center parties (VVD, NSC, BBB, CDA, ChristenUnie) not validated
- Per-party strict sign checks excluded — statistical mean check
- `political_axis.py` not updated (out of scope per requirements)

## Context & Research

### Relevant Code and Patterns

- `analysis/config.py` — existing constants module with `__all__`, `_PARTY_NORMALIZE` at lines 247-256
- `analysis/svd_labels.py` — `compute_flip_direction` at lines 127-166, uses inline `RIGHT_PARTIES`/`LEFT_PARTIES`
- `analysis/explorer_data.py` — `load_party_scores_all_windows_aligned` at lines 212-241, returns `{party: [[x,y] per window]}`
- `analysis/trajectory.py` — `_load_window_ids` at line 121 (not exported in `__all__`)
- `tests/conftest.py` — `tmp_duckdb_path` fixture at line 70, `tmp_duckdb_conn` fixture at line 76
- `tests/test_svd_labels.py` — existing tests for `compute_flip_direction` with synthetic data

### Key Structural Insight

`load_party_scores_all_windows_aligned` returns `{party: [[x, y], [x, y], ...]}` — data grouped by party, not by window. To validate per window, the test must iterate window indices and build per-window dicts: `{party: [x, y]}` where index matches the window position.

`compute_flip_direction(component, {party: [scores]})` indexes into `scores[component-1]`, so:
- `compute_flip_direction(1, party_scores)` checks x-axis orientation
- `compute_flip_direction(2, party_scores)` checks y-axis orientation

## Key Technical Decisions

- **Synthetic DuckDB fixture data, not real DB**: Temporary DB with controlled `party_axis_scores` rows avoids dependency on a populated real database. Follows existing pattern from `test_analysis.py`.
- **Extract window-indexing helper**: A helper `build_window_party_scores(scores_by_party, window_idx)` separates data transformation from DB access — enables unit testing the logic without DuckDB.
- **`_PARTY_NORMALIZE` for alias handling**: Normalize party names from DB before building `party_scores` dict. DB may return "GL" while canonical sets expect "GroenLinks-PvdA".

## Open Questions

### Resolved During Planning

- **DB fixture vs real DB**: Use synthetic fixture data in temporary DuckDB. This is the pattern used by `test_analysis.py` and gives full control over the test scenario.
- **Per-window iteration**: Data is `{party: [[x,y] per window]}` — iterate by window index, not by key lookup.
- **`political_axis.py` scope**: Not updated. Uses separate `right_parties`/`left_parties` for PCA centroid orientation, distinct concern from this validation.

### Deferred to Implementation

- **Test DB schema exactness**: The `party_axis_scores` schema (column names, nullability) should be verified against `explorer_data.py` query at implementation time.

## Implementation Units

- [ ] **Unit 1: Add canonical party sets to `config.py`**

**Goal:** Add `CANONICAL_RIGHT` and `CANONICAL_LEFT` frozensets as the single source of truth.

**Requirements:** R1

**Dependencies:** None

**Files:**
- Modify: `analysis/config.py`

**Approach:**
- Add `CANONICAL_RIGHT = frozenset({"PVV", "FVD", "JA21", "SGP"})` matching AGENTS.md exactly
- Add `CANONICAL_LEFT = frozenset({"SP", "PvdA", "GL", "GroenLinks", "GroenLinks-PvdA", "DENK", "PvdD", "Volt"})` matching svd_labels.py LEFT_PARTIES exactly
- Add both to `__all__`

**Patterns to follow:**
- `CURRENT_PARLIAMENT_PARTIES` frozenset pattern at `config.py` line 235

**Test scenarios:**
- Test expectation: none — this is a data definition change, not behavioral code

**Verification:**
- `CANONICAL_RIGHT` and `CANONICAL_LEFT` accessible via `from analysis.config import CANONICAL_RIGHT, CANONICAL_LEFT`

---

- [ ] **Unit 2: Update `svd_labels.py` to import from `config.py`**

**Goal:** `compute_flip_direction` uses canonical sets from config instead of inline definitions.

**Requirements:** R1

**Dependencies:** Unit 1

**Files:**
- Modify: `analysis/svd_labels.py`

**Approach:**
- Replace inline `RIGHT_PARTIES` and `LEFT_PARTIES` frozensets with:
  ```python
  from analysis.config import CANONICAL_RIGHT, CANONICAL_LEFT
  RIGHT_PARTIES = CANONICAL_RIGHT  # backward compat alias
  LEFT_PARTIES = CANONICAL_LEFT   # backward compat alias
  ```
- This preserves any external callers that import `RIGHT_PARTIES`/`LEFT_PARTIES` from `svd_labels`

**Patterns to follow:**
- Alias pattern (re-export) rather than removing the old names — backward compat

**Test scenarios:**
- Happy path: `compute_flip_direction` produces same results as before (baseline established by existing tests in `test_svd_labels.py`)
- Existing tests in `test_svd_labels.py` run and pass after the import swap

**Verification:**
- `pytest tests/test_svd_labels.py` passes

---

- [ ] **Unit 3: Extract `build_window_party_scores` helper in `explorer_data.py`**

**Goal:** Separate window-indexing logic from DB access so it can be unit tested without DuckDB.

**Requirements:** R2, R3

**Dependencies:** None

**Files:**
- Create: `analysis/explorer_data.py` (add function)

**Approach:**
Add a helper:
```python
def build_window_party_scores(
    scores_by_party: Dict[str, List[List[float]]],
    window_idx: int
) -> Dict[str, List[float]]:
    """Extract scores for one window as {party: [x, y]} for compute_flip_direction."""
```

The function takes the output of `load_party_scores_all_windows_aligned` and extracts `scores_by_party[party][window_idx]` for all parties, returning `{party: [x, y]}`. Returns empty dict if window_idx is out of range.

**Patterns to follow:**
- `load_party_scores_all_windows_aligned` pattern at `explorer_data.py` line 212

**Test scenarios:**
- Happy path: Given `{"PVV": [[0.5, 0.3], [0.6, 0.4]], "SP": [[-0.4, -0.2], [-0.5, -0.3]]}` and `window_idx=0`, returns `{"PVV": [0.5, 0.3], "SP": [-0.4, -0.2]}`
- Edge case: `window_idx=99` out of range → returns `{}`
- Edge case: Empty input dict → returns `{}`

**Verification:**
- Unit tests pass without DuckDB

---

- [ ] **Unit 4: Create `tests/test_axis_political_orientation.py`**

**Goal:** Integration test validating political compass orientation against DuckDB data.

**Requirements:** R2, R3, R4, R5

**Dependencies:** Units 1, 2, 3

**Files:**
- Create: `tests/test_axis_political_orientation.py`

**Approach:**
Two-layer test structure:

1. **Synthetic fixture layer** (DuckDB integration test):
   - Create temporary DB with `party_axis_scores` table
   - Insert controlled rows: correct orientation (right_mean > left_mean) and incorrect orientation (right_mean < left_mean)
   - Call `load_party_scores_all_windows_aligned` and `build_window_party_scores`
   - Assert orientation checks pass/fail correctly

2. **Validation assertions** (layered on helper from Unit 3):
   - For each window (iterate `scores_by_party[party]` length):
     - Build per-window dict via `build_window_party_scores`
     - Call `compute_flip_direction(1, party_scores)` → assert `False` (no flip needed)
     - Call `compute_flip_direction(2, party_scores)` → assert `False`
   - On failure: assert message includes window, axis, right_mean, left_mean

Use `tmp_duckdb_conn` fixture. Create schema and insert rows in test setup.

**Patterns to follow:**
- `test_analysis.py` fixture setup pattern (lines 13-60) for synthetic SVD vector setup
- `test_svd_labels.py` assertion style for `compute_flip_direction` validation

**Test scenarios:**
- Happy path (correct orientation): Right mean > left mean on both axes → both `compute_flip_direction` calls return `False`
- Error path (incorrect orientation): Right mean < left mean → at least one call returns `True`, test fails with clear message
- Edge case: Party not in canonical sets → gracefully skipped (no crash)
- Edge case: Empty party list → returns `False` (no flip)
- Edge case: Aliased party name ("GL" vs "GroenLinks-PvdA") → normalized before check

**Verification:**
- `pytest tests/test_axis_political_orientation.py` runs and passes
- `pytest tests/test_svd_labels.py` still passes (backward compat check)

## System-Wide Impact

- **Error propagation**: No error paths in this feature — orientation violations produce assertion failures, not exceptions
- **Unchanged invariants**: `compute_flip_direction` output unchanged for existing callers (alias re-export)
- **API surface parity**: No new public APIs; `CANONICAL_RIGHT`/`CANONICAL_LEFT` are read-only constants

## Risks & Dependencies

| Risk | Mitigation |
|------|------------|
| DuckDB fixture schema mismatch | Verify `party_axis_scores` column names against `explorer_data.py` query at implementation time |
| Window index boundary errors | `build_window_party_scores` returns `{}` for out-of-range indices — graceful degradation |
| `_PARTY_NORMALIZE` aliases incomplete | Add aliases as needed during implementation — test with edge cases |

## Sources & References

- **Origin document:** [docs/brainstorms/2026-04-05-right-wing-party-axis-validation-requirements.md](docs/brainstorms/2026-04-05-right-wing-party-axis-validation-requirements.md)
- **AGENTS.md convention:** `docs/solutions/best-practices/svd-labels-voting-patterns-not-semantics.md`
- Related code: `analysis/svd_labels.py`, `analysis/config.py`, `analysis/explorer_data.py`
- Related tests: `tests/test_svd_labels.py`, `tests/test_analysis.py`