# Rule 53: Full Slot Migration - No Deprecation Notes

🚨 **CRITICAL**: When migrating slots from `slot_fixes.yaml`:

1. **Follow the `revision` section EXACTLY** - The `slot_fixes.yaml` file specifies the exact replacement slots and classes to use
2. **Perform FULL MIGRATION** - Completely remove the deprecated slot from the entity class
3. **Do NOT add deprecation notes** - Never keep both old and new slots with deprecation markers

---

## 🚨 slot_fixes.yaml is AUTHORITATIVE AND CURATED 🚨

**File Location**: `schemas/20251121/linkml/modules/slots/slot_fixes.yaml`

**THIS FILE IS THE SINGLE SOURCE OF TRUTH FOR ALL SLOT MIGRATIONS.**

The `slot_fixes.yaml` file has been **manually curated** to specify the exact replacement slots and classes for each deprecated slot. The revisions are based on:

1. **Ontology analysis** - Each replacement was chosen based on alignment with base ontologies (CIDOC-CRM, RiC-O, PROV-O, Schema.org, etc.)
2. **Semantic correctness** - Revisions reflect the intended meaning of the original slot
3. **Pattern consistency** - Follows established naming conventions (Rule 39: RiC-O style, Rule 43: singular nouns)
4. **Class hierarchy design** - Type/Types pattern (Rule 0b) applied where appropriate

**YOU MUST NOT**:
- ❌ Substitute different slots than those specified in `revision`
- ❌ Use your own judgment to pick "similar" slots
- ❌ Skip the revision and invent new mappings
- ❌ Partially apply the revision (e.g., use the slot but not the class)

**YOU MUST**:
- ✅ Follow the `revision` section TO THE LETTER
- ✅ Use EXACTLY the slots and classes specified
- ✅ Apply ALL components of the revision (both slots AND classes)
- ✅ Interpret `link_branch` fields correctly (see below)
- ✅ Update `processed.status: true` after completing migration

---

## Understanding `link_branch` in Revision Plans

🚨 **CRITICAL**: The `link_branch` field in revision plans indicates **nested class attributes**. Items with `link_branch: N` are slots/classes that belong TO the primary class, not standalone replacements.

### How to Interpret `link_branch`

| Revision Item | Meaning |
|---------------|---------|
| Items **WITHOUT** `link_branch` | **PRIMARY** slot and class to create |
| Items **WITH** `link_branch: 1` | First attribute branch that the primary class needs |
| Items **WITH** `link_branch: 2` | Second attribute branch that the primary class needs |
| Items **WITH** `link_branch: N` | Nth attribute branch for the primary class |

### Example: `visitor_count` Revision

```yaml
- original_slot_id: https://nde.nl/ontology/hc/slot/visitor_count
  revision:
    - label: has_or_had_quantity     # PRIMARY SLOT (no link_branch)
      type: slot
    - label: Quantity                 # PRIMARY CLASS (no link_branch)
      type: class
    - label: has_or_had_measurement_unit   # Quantity needs this slot
      type: slot
      link_branch: 1                        # ← Branch 1: unit attribute
    - label: MeasureUnit                    # Range of has_or_had_measurement_unit
      type: class
      value:
        - visitors
      link_branch: 1
    - label: temporal_extent               # Quantity needs this slot too
      type: slot
      link_branch: 2                        # ← Branch 2: time attribute
    - label: TimeSpan                       # Range of temporal_extent
      type: class
      link_branch: 2
```

**Interpretation**: This creates:
1. **Primary**: `has_or_had_quantity` slot → `Quantity` class
2. **Branch 1**: `Quantity.has_or_had_measurement_unit` → `MeasureUnit` (with value "visitors")
3. **Branch 2**: `Quantity.temporal_extent` → `TimeSpan`

### Resulting Class Structure

```yaml
# The Quantity class should have these slots:
Quantity:
  slots:
    - has_or_had_measurement_unit  # From link_branch: 1
    - temporal_extent              # From link_branch: 2
```

### Complex Example: `visitor_conversion_rate`

```yaml
- original_slot_id: https://nde.nl/ontology/hc/slot/visitor_conversion_rate
  revision:
    - label: has_or_had_conversion_rate    # PRIMARY SLOT
      type: slot
    - label: ConversionRate                 # PRIMARY CLASS
      type: class
    - label: has_or_had_type               # ConversionRate.has_or_had_type
      type: slot
      link_branch: 1
    - label: ConversionRateType            # Abstract type class
      type: class
      link_branch: 1
    - label: includes_or_included          # ConversionRateType hierarchy slot
      type: slot  
      link_branch: 1
    - label: ConversionRateTypes           # Concrete subclasses file
      type: class
      link_branch: 1
    - label: temporal_extent               # ConversionRate.temporal_extent
      type: slot
      link_branch: 2
    - label: TimeSpan                      # Range of temporal_extent
      type: class
      link_branch: 2
```

**Interpretation**:
1. **Primary**: `has_or_had_conversion_rate` → `ConversionRate`
2. **Branch 1**: Type hierarchy with `ConversionRateType` (abstract) + `ConversionRateTypes` (concrete subclasses)
3. **Branch 2**: Temporal tracking via `temporal_extent` → `TimeSpan`

### Migration Checklist for `link_branch` Revisions

- [ ] Create/verify PRIMARY slot exists
- [ ] Create/verify PRIMARY class exists
- [ ] For EACH `link_branch: N`:
  - [ ] Add the branch slot to PRIMARY class's `slots:` list
  - [ ] Import the branch slot file
  - [ ] Import the branch class file (if creating new class)
  - [ ] Verify range of branch slot points to branch class
- [ ] Update consuming class to use PRIMARY slot (not deprecated slot)
- [ ] Update examples to show nested structure

---

## Mandatory: Follow slot_fixes.yaml Revisions Exactly

**The `revision` section in `slot_fixes.yaml` is AUTHORITATIVE.** Do not substitute different slots based on your own judgment.

**Example from slot_fixes.yaml**:
```yaml
- original_slot_id: https://nde.nl/ontology/hc/slot/actual_start
  revision:
    - label: begin_of_the_begin   # ← USE THIS SLOT
      type: slot
    - label: TimeSpan             # ← USE THIS CLASS
      type: class
```

**CORRECT**: Use `begin_of_the_begin` slot (as specified)
**WRONG**: Substitute `has_actual_start_date` (not in revision)

## The Problem

Adding deprecation notes while keeping both old and new slots:
- Creates schema bloat with redundant properties
- Confuses data consumers about which slot to use
- Violates single-source-of-truth principle
- Complicates future data validation

## Anti-Pattern (WRONG)

```yaml
# WRONG - Keeping deprecated slot with deprecation note
classes:
  TemporaryLocation:
    slots:
      - actual_start        # OLD - kept with deprecation note
      - actual_end          # OLD - kept with deprecation note
      - has_actual_start_date  # NEW
      - has_actual_end_date    # NEW
    slot_usage:
      actual_start:
        deprecated: |
          DEPRECATED: Use has_actual_start_date instead.
        # ... more deprecation documentation
```

## Correct Pattern

```yaml
# CORRECT - Only new slots, old slots completely removed
classes:
  TemporaryLocation:
    slots:
      - has_actual_start_date  # NEW - only new slots present
      - has_actual_end_date    # NEW
    # NO slot_usage for deprecated slots - they don't exist in this class
```

## Migration Steps

When processing a slot from `slot_fixes.yaml`:

1. **Identify affected entity class(es)**
2. **Remove old slot from imports** (if dedicated import file exists)
3. **Remove old slot from slots list**
4. **Remove any slot_usage for old slot**
5. **Add new slot import** (if not already present)
6. **Add new slot to slots list**
7. **Add slot_usage for new slot** (if range override or customization needed)
8. **Update examples** to use new slot
9. **Validate with gen-owl**

## What Happens to Old Slot Files

The old slot files in `modules/slots/` (e.g., `actual_start.yaml`, `activities_societies.yaml`) are **NOT deleted** because:
- Other entity classes might still use them
- They serve as documentation of the old schema
- They can be archived when all usages are migrated

However, the old slots are **removed from the entity class** being migrated.

## Example: TemporaryLocation Migration

**Before** (with old slots):
```yaml
imports:
  - ../slots/actual_end
  - ../slots/actual_start
  - ../slots/has_actual_start_date
  - ../slots/has_actual_end_date

slots:
  - actual_end
  - actual_start
  - has_actual_start_date
  - has_actual_end_date
```

**After** (fully migrated):
```yaml
imports:
  # actual_end and actual_start imports REMOVED
  - ../slots/has_actual_start_date
  - ../slots/has_actual_end_date

slots:
  # actual_end and actual_start REMOVED from list
  - has_actual_start_date
  - has_actual_end_date
```

## Slot Usage for New Slots

Only add `slot_usage` for the new slot if you need to:
- Override the range for this specific class
- Add class-specific examples
- Add class-specific constraints

Do NOT add `slot_usage` just to document that it replaces an old slot.

## Recording in slot_fixes.yaml

When marking a slot as processed:

```yaml
- original_slot_id: https://nde.nl/ontology/hc/slot/actual_start
  processed:
    status: true
    timestamp: '2026-01-14T16:00:00Z'
    session: "session-2026-01-14-type-migration"
    notes: "FULLY MIGRATED: TemporaryLocation - actual_start REMOVED, using temporal_extent with TimeSpan.begin_of_the_begin (Rule 53)"
```

Note the "FULLY MIGRATED" prefix in notes to confirm this was a complete removal, not a deprecation-in-place.

---

## ⚠️ Common Mistakes to Avoid ⚠️

### Mistake 1: Substituting Different Slots

**slot_fixes.yaml specifies**:
```yaml
- original_slot_id: https://nde.nl/ontology/hc/slot/actual_start
  revision:
    - label: begin_of_the_begin   # ← MUST USE THIS
      type: slot
    - label: TimeSpan             # ← WITH THIS CLASS
      type: class
```

| Action | Status |
|--------|--------|
| Using `begin_of_the_begin` with `TimeSpan` | ✅ CORRECT |
| Using `has_actual_start_date` (invented) | ❌ WRONG |
| Using `start_date` (different slot) | ❌ WRONG |
| Using `begin_of_the_begin` WITHOUT `TimeSpan` | ❌ WRONG (incomplete) |

### Mistake 2: Partial Application

The revision often specifies MULTIPLE components that work together:

```yaml
revision:
  - label: has_or_had_type       # ← Slot for linking
    type: slot
  - label: BackupType            # ← Abstract base class
    type: class
  - label: includes_or_included  # ← Slot for hierarchy
    type: slot
  - label: BackupTypes           # ← Concrete subclasses
    type: class
```

**All four components** are part of the migration. Don't just use `has_or_had_type` and ignore the class structure.

### Mistake 3: Using `temporal_extent` Slot Correctly

When `slot_fixes.yaml` specifies TimeSpan-based revision:

```yaml
revision:
  - label: begin_of_the_begin
    type: slot
  - label: TimeSpan
    type: class
```

This means: **Use the `temporal_extent` slot** (which has `range: TimeSpan`) and access the temporal bounds via TimeSpan's slots:

```yaml
# CORRECT: Use temporal_extent with TimeSpan structure
temporal_extent:
  begin_of_the_begin: '2020-06-15'
  end_of_the_end: '2022-03-15'

# WRONG: Create new has_actual_start_date slot
has_actual_start_date: '2020-06-15'  # ❌ Not in revision!
```

### Mistake 4: Not Updating Examples

When migrating slots, **update ALL examples** in the class file:
- Description examples (in class description)
- slot_usage examples
- Class-level examples (at bottom of file)

---

## Verification Checklist

Before marking a slot as processed:

- [ ] Read the `revision` section completely
- [ ] Identified ALL slots and classes in revision
- [ ] Removed old slot from imports
- [ ] Removed old slot from slots list
- [ ] Removed old slot from slot_usage
- [ ] Added new slot(s) per revision
- [ ] Added new class import(s) per revision
- [ ] Updated ALL examples to use new slots
- [ ] Validated with `linkml-lint` or `gen-owl`
- [ ] Updated `slot_fixes.yaml` with:
  - `status: true`
  - `timestamp` (ISO 8601)
  - `session` identifier
  - `notes` with "FULLY MIGRATED:" prefix

---

## See Also

- Rule 9: Enum-to-Class Promotion (single source of truth principle)
- Rule 0b: Type/Types File Naming Convention
- Rule: Slot Naming Convention (Current Style)
- `.opencode/ENUM_TO_CLASS_PRINCIPLE.md`
- `schemas/20251121/linkml/modules/slots/slot_fixes.yaml` - **AUTHORITATIVE** master list of migrations