# Security Audit: Personalization Correctness Verification

## Scope

Audited `tidal/tests/pg1_personalization_correctness.rs` — a pure integration test file. No production code changes.

## Verdict: PASS

This feature adds only test code. There are no security implications.

## Findings

### Attack Surface

**None.** This feature:

- Adds no new public API endpoints
- Modifies no production code paths
- Introduces no new dependencies
- Does not handle user input, network data, or file I/O beyond ephemeral test databases
- Does not introduce any `unsafe` code

### Data Safety

- All tests use `TidalDb::builder().ephemeral()` — no persistent data is created or modified
- No secrets, credentials, or PII are present in test data
- Entity IDs and user IDs are synthetic test constants

### Dependency Review

No new crate dependencies were added. The test file uses only existing `tidaldb` public API types.

### Numerical Safety

- Decay score computations use `f64` arithmetic with documented tolerance bounds (1e-6)
- The `analytical_decay_score` helper uses `saturating_sub` to prevent underflow on timestamp differences
- `relative_error` handles the zero-denominator case explicitly
- The `no_nan_or_infinity_in_scores` test guards against IEEE 754 special values across 6 profiles with edge-case signal weights (1e15, 1e-15, zero)

## Checklist

| Check | Status |
|-------|--------|
| No new unsafe code | PASS |
| No new dependencies | PASS |
| No secrets or PII | PASS |
| No file system side effects | PASS (ephemeral DBs only) |
| No network access | PASS |
| No privilege escalation paths | PASS |