vhs-watch

What this skill does

# VHS Watch: Monitoring & Watchlists

Track VHS Berlin courses and searches for changes over time.

## Workflow

### Action: Save a Watch

**User request:** "Watch this search" or "Monitor B1 German courses in Mitte"

#### Step 1: Capture the Query
Extract:
- User-friendly label (e.g., "B1 German evening Mitte")
- Query type: `natural_language`, `course_id`, `district_location`, `keyword`
- Query payload (JSON):
  ```json
  {
    "text": "B1 German evening courses in Mitte",
    "parsed": {
      "district": "mitte",
      "category": "german",
      "level": "B1",
      "time": "evening"
    }
  }
  ```

#### Step 2: Store the Watch
```sql
INSERT INTO watched_searches (label, query_type, query_payload, created_at, enabled)
VALUES (
  'B1 German evening Mitte',
  'natural_language',
  '{"text": "...", "parsed": {...}}',
  datetime('now'),
  1
);
```

#### Step 3: Take Initial Snapshot
Run the search immediately using `vhs-search` skill, then store the baseline:

```sql
INSERT INTO snapshots (watch_id, extracted_at, result_hash, result_count, result_course_ids)
VALUES (
  last_insert_rowid(),
  datetime('now'),
  'sha256_of_sorted_ids',
  5,
  '["VHS-12345", "VHS-12346", ...]'
);
```

#### Step 4: Confirm
```
✅ Saved watch: "B1 German evening Mitte"
Found 5 matching courses. I'll check for changes when you ask.
```

---

### Action: Check Watches

**User request:** "Check my watches" or "Any updates?"

#### Step 1: Load Active Watches
```sql
SELECT watch_id, label, query_type, query_payload, last_checked_at
FROM watched_searches
WHERE enabled = 1
ORDER BY last_checked_at ASC NULLS FIRST;
```

#### Step 2: For Each Watch, Refresh Results
Re-run the search using `vhs-search` skill or direct query.

#### Step 3: Compare with Last Snapshot
```sql
SELECT result_course_ids
FROM snapshots
WHERE watch_id = ?
ORDER BY extracted_at DESC
LIMIT 1;
```

Parse the JSON arrays and compare:
- **New courses**: IDs in current but not in previous
- **Disappeared courses**: IDs in previous but not in current
- **Still present**: IDs in both

For still-present courses, check if details changed:
```sql
SELECT source_course_id, booking_status, price_text, start_date
FROM courses
WHERE source_course_id IN (...)
ORDER BY extracted_at DESC;
```

Compare latest vs. previous:
- Booking status change
- Price change
- Date change

#### Step 4: Log Events
For each detected change:
```sql
INSERT INTO course_events (course_id, event_type, old_value, new_value, detected_at, watch_id)
VALUES (
  'VHS-12345',
  'status_change',
  '{"booking_status": "Warteliste"}',
  '{"booking_status": "Anmeldung möglich"}',
  datetime('now'),
  ?
);
```

#### Step 5: Store New Snapshot
```sql
INSERT INTO snapshots (watch_id, extracted_at, result_hash, result_count, result_course_ids)
VALUES (...);
```

Update the watch:
```sql
UPDATE watched_searches
SET last_checked_at = datetime('now')
WHERE watch_id = ?;
```

#### Step 6: Report Changes
```
## Updates for "B1 German evening Mitte"

**New courses (2):**
- Deutsch B1.2 Intensiv — Mitte, VHS Linienstraße, starts May 20
- Deutsch B1 Abendkurs — Mitte, VHS Antonstraße, starts Jun 1

**Status changes (1):**
- "Deutsch B1.1 Kompakt" — now open for registration (was waitlist)

**No longer available (1):**
- "Deutsch B1 Wochenende" — removed from listing
```

If no changes:
```
✅ No changes detected in your 3 active watches.
Last checked: 2 days ago
```

---

### Action: List Watches

**User request:** "Show my watches" or "What am I monitoring?"

```sql
SELECT watch_id, label, query_type, created_at, last_checked_at, enabled
FROM watched_searches
ORDER BY created_at DESC;
```

Present:
```
## Your Watches

1. **B1 German evening Mitte** (active)
   - Created: Apr 12, 2026
   - Last checked: Apr 18, 2026 (5 courses)

2. **Pottery weekend classes** (active)
   - Created: Apr 5, 2026
   - Last checked: never

3. **Spanish A2 Neukölln** (paused)
   - Created: Mar 20, 2026
   - Last checked: Apr 1, 2026
```

---

### Action: Remove a Watch

**User request:** "Stop watching B1 German" or "Remove watch #2"

```sql
DELETE FROM watched_searches
WHERE watch_id = ? OR label LIKE '%...%';
```

Confirm:
```
✅ Removed watch: "B1 German evening Mitte"
```

---

## Tips

- **Check frequency**: Recommend checking daily or weekly, not every hour (to avoid hammering VHS site)
- **Change detection**: SHA-256 hash of sorted course IDs for fast snapshot comparison
- **Event logging**: Keep a permanent log of changes for historical reference
- **Pause vs. delete**: Offer to pause watches instead of deleting (can resume later)

## See Also

- `vhs-search` skill (for running the actual searches)
- `vhs-digest` skill (for weekly summaries)
- `data/schema.sql` (for database structure)