# UAT: FDA Label Paradigm Shift (Epoch Supersession)

**Date:** YYYY-MM-DD
**Feature:** Epoch-Based Invalidation
**Status:** [ ] PASS / [ ] FAIL / [ ] BLOCKED

## Scenario

FDA updates the drug label for Semaglutide with significant new safety information. This creates a new "epoch" that supersedes hundreds of pre-existing assertions based on outdated label information.

Key validation: The epoch switch must invalidate O(1), not iterate O(N) through all assertions.

## Acceptance Criteria

| Criterion | Expected | Met? |
|-----------|----------|------|
| Old epoch assertions | Exist in storage | [ ] |
| New epoch created | Hash returned | [ ] |
| EpochAware query | Returns only new epoch | [ ] |
| Invalidation performance | O(1) not O(N) | [ ] |
| Old data still queryable | With explicit epoch filter | [ ] |

## Test Matrix

| Step | Action | Expected | Actual | Status |
|------|--------|----------|--------|--------|
| 1 | Create 100 old-epoch assertions | 100 hashes returned | | [ ] |
| 2 | Create new epoch | Epoch hash returned | | [ ] |
| 3 | Create new-epoch assertion | Hash returned | | [ ] |
| 4 | Query with EpochAware lens | Only new assertion | | [ ] |
| 5 | Query old epoch explicitly | Old assertions returned | | [ ] |
| 6 | Measure invalidation time | < 10ms | | [ ] |

## Setup Commands

```bash
# Start StemeDB
cargo run --bin stemedb-api &
sleep 2
```

## Test Commands

### Step 1: Ingest Old-Epoch Assertions (Pre-FDA Update)

```bash
# Create 100 assertions in the "pre-2024-label" epoch
for i in $(seq 1 100); do
  curl -s -X POST http://localhost:18180/v1/assertions \
    -H "Content-Type: application/json" \
    -d "{
      \"subject\": \"Semaglutide\",
      \"predicate\": \"has_boxed_warning\",
      \"object\": {\"Boolean\": false},
      \"confidence\": 0.9,
      \"source_class\": \"Clinical\",
      \"epoch\": \"0000000000000000000000000000000000000000000000000000000000000001\"
    }" > /dev/null
done
echo "Created 100 old-epoch assertions"
```

**Expected:** 100 assertions created
**Actual:**
**Status:** [ ]

### Step 2: Create New Epoch (FDA Label Update)

```bash
curl -X POST http://localhost:18180/v1/epochs \
  -H "Content-Type: application/json" \
  -d '{
    "name": "FDA Label Update 2024",
    "description": "New boxed warning added for thyroid C-cell tumors",
    "supersedes": "0000000000000000000000000000000000000000000000000000000000000001",
    "effective_date": "2024-06-15T00:00:00Z"
  }'
```

**Expected:** `{"epoch_id": "..."}`
**Actual:**
**Status:** [ ]

### Step 3: Create New-Epoch Assertion

```bash
curl -X POST http://localhost:18180/v1/assertions \
  -H "Content-Type: application/json" \
  -d '{
    "subject": "Semaglutide",
    "predicate": "has_boxed_warning",
    "object": {"Boolean": true},
    "confidence": 1.0,
    "source_class": "Regulatory",
    "epoch": "<NEW_EPOCH_ID_FROM_STEP_2>"
  }'
```

**Expected:** Hash returned
**Actual:**
**Status:** [ ]

### Step 4: Query with EpochAware Lens

```bash
curl "http://localhost:18180/v1/query?subject=Semaglutide&predicate=has_boxed_warning&lens=epoch-aware"
```

**Expected:** Only the new-epoch assertion (has_boxed_warning = true)
**Actual:**
**Status:** [ ]

### Step 5: Query Old Epoch Explicitly

```bash
curl "http://localhost:18180/v1/query?subject=Semaglutide&predicate=has_boxed_warning&epoch=0000000000000000000000000000000000000000000000000000000000000001"
```

**Expected:** Returns old assertions (has_boxed_warning = false)
**Actual:**
**Status:** [ ]

### Step 6: Measure Invalidation Performance

The epoch creation (Step 2) should complete in O(1) time, regardless of how many assertions exist in the old epoch.

```bash
# Time the epoch creation
time curl -X POST http://localhost:18180/v1/epochs \
  -H "Content-Type: application/json" \
  -d '{
    "name": "Performance Test Epoch",
    "supersedes": "0000000000000000000000000000000000000000000000000000000000000001"
  }'
```

**Expected:** < 10ms (should not scan 100 assertions)
**Actual:**
**Status:** [ ]

## Sign-Off Checklist

- [ ] Old epoch assertions preserved in storage
- [ ] New epoch created successfully
- [ ] EpochAware lens filters to current epoch
- [ ] Time-travel query to old epoch works
- [ ] Invalidation is O(1) not O(N)

## Notes

*Verify that epoch supersession happens at query time (via lens), not at write time (no mass updates).*

---

**Tester:**
**Date:**
**Result:**