# Extracted pattern examples (representative snippets)

Note: snippets are verbatim extracts from repository files (Phase 1). Paths shown.

## DuckDB connect + schema init (database.py)
```python
conn = duckdb.connect(self.db_path)

# Create sequence for auto-incrementing IDs
try:
    conn.execute("CREATE SEQUENCE IF NOT EXISTS motions_id_seq START 1")
except:
    pass

# Create tables with proper ID handling
conn.execute("""
    CREATE TABLE IF NOT EXISTS motions (
        id INTEGER DEFAULT nextval('motions_id_seq'),
        title TEXT NOT NULL,
        description TEXT,
        date DATE,
        policy_area TEXT,
        voting_results JSON,
        winning_margin FLOAT,
        controversy_score FLOAT,
        layman_explanation TEXT,
        externe_identifier TEXT,
        body_text TEXT,
        url TEXT UNIQUE,
        created_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP,
        PRIMARY KEY (id)
    )
""")
conn.close()
```

## Read-only compute worker (svd_pipeline.py)
```python
conn = duckdb.connect(db_path, read_only=True)
try:
    rows = conn.execute(
        "SELECT motion_id, mp_name, vote FROM mp_votes WHERE date BETWEEN ? AND ?",
        (start_date, end_date),
    ).fetchall()
finally:
    conn.close()
```

## Requests with retry/backoff (ai_provider.py)
```python
resp = requests.post(url, json=json, headers=headers, timeout=10)
...
if getattr(resp, "status_code", 0) == 429:
    if attempt == retries:
        raise ProviderError(f"Provider returned HTTP {resp.status_code}")
    retry_after = None
    raw = resp.headers.get("Retry-After") if getattr(resp, "headers", None) else None
    if raw:
        try:
            retry_after = int(raw)
        except Exception:
            try:
                dt = parsedate_to_datetime(raw)
                now = datetime.now(tz=dt.tzinfo or timezone.utc)
                secs = (dt - now).total_seconds()
                retry_after = max(0, int(secs))
            except Exception:
                retry_after = None

    if retry_after is not None:
        time.sleep(retry_after)
        continue
```

## Embedding batch + per-item fallback (pipeline/ai_provider_wrapper.py)
```python
for start in range(0, len(texts), batch_size):
    chunk = texts[i:end]
    emb_chunk, emb_exc = _attempt_batch(chunk, i)
    if emb_chunk is not None:
        for j, emb in enumerate(emb_chunk):
            results[i + j] = emb
        i = end
        continue

    # batch failed -> fallback to per-item attempts
    for j in range(i, end):
        t = texts[j]
        single, single_exc = _attempt_batch([t], j)
        if single:
            results[j] = single[0]
            continue
        results[j] = None
```

## Similarity compute (similarity/compute.py)
```python
# Ensure consistent dimensionality: pad shorter vectors with zeros
lengths = [len(v) for v in vecs]
max_dim = max(lengths)
if len(set(lengths)) != 1:
    logger.warning(
        "Inconsistent vector dimensions detected (max=%d). Padding shorter vectors with zeros.",
        max_dim,
    )

matrix = np.zeros((len(vecs), max_dim), dtype=np.float32)
for i, v in enumerate(vecs):
    matrix[i, : len(v)] = v

# Normalize rows and compute cosine similarity
norms = np.linalg.norm(matrix, axis=1, keepdims=True)
norms[norms == 0] = 1.0
normalized = matrix / norms
sim = normalized @ normalized.T
```