# Session Complete: CustodianAppellation Phase 2 Refactoring

**Date**: 2025-11-22, 18:12 UTC  
**Status**: ✅ COMPLETE  
**Schema Version**: 0.1.0 → 0.2.0 (Phase 2)

---

## What We Accomplished

### Phase 2: Moving Appellations from Custodian to CustodianName

**Goal**: Align with W3C SKOS best practices by making appellations variants of names (not hub identifiers).

**Results**:
- ✅ Refactored `CustodianAppellation` to connect to `CustodianName` (not `Custodian`)
- ✅ Changed property from `crm:P1_is_identified_by` → `skos:altLabel`
- ✅ Created inverse relationship: `variant_of_name` using `skos:broader`
- ✅ Updated all schema module files
- ✅ Deprecated old `appellations.yaml` slot with migration instructions
- ✅ Generated RDF outputs (4 formats, 160-458 KB)
- ✅ Generated Mermaid ER diagram (176 lines)
- ✅ Validated schema successfully

---

## Key Architecture Changes

### Before (Phase 1)
```
Custodian --[crm:P1_is_identified_by]--> CustodianAppellation
```
*Problem*: Suggests appellations identify the hub (semantic confusion)

### After (Phase 2)
```
Custodian --[skos:prefLabel]--> CustodianName --[skos:altLabel]--> CustodianAppellation
```
*Correct*: Appellations are variants of the canonical name

---

## Files Modified

### Schema Modules (5 files)
1. ✅ `modules/classes/Appellation.yaml` - Changed to connect to CustodianName
2. ✅ `modules/classes/Custodian.yaml` - Removed appellations slot
3. ✅ `modules/classes/CustodianName.yaml` - Added alternative_names slot
4. ✅ `modules/slots/alternative_names.yaml` - NEW (CustodianName → Appellation)
5. ✅ `modules/slots/variant_of_name.yaml` - NEW (Appellation → CustodianName, inverse)

### Main Schema
6. ✅ `01_custodian_name_modular.yaml` - Updated imports and change log

### Deprecated
7. ⚠️ `modules/slots/appellations.yaml` - DEPRECATED with migration path

---

## Generated Outputs

### RDF (4 formats)
```bash
schemas/20251121/rdf/
├── 01_custodian_name_modular_20251122_181217.owl.ttl  (160 KB)
├── 01_custodian_name_modular_20251122_181224.nt       (458 KB)
├── 01_custodian_name_modular_20251122_181224.jsonld   (382 KB)
└── 01_custodian_name_modular_20251122_181224.rdf      (330 KB)
```

### UML Diagrams (1 file)
```bash
schemas/20251121/uml/mermaid/
└── 01_custodian_name_modular_20251122_181237_er.mmd  (176 lines)
```

**Verified Relationships**:
```mermaid
CustodianName ||--}o CustodianAppellation : "alternative_names"
CustodianAppellation ||--|o CustodianName : "variant_of_name"
```

---

## Validation Status

### Schema Compilation ✅
```bash
$ gen-owl -f ttl 01_custodian_name_modular.yaml
# SUCCESS: 160 KB output, no errors
```

### ER Diagram ✅
- ✅ CustodianName → CustodianAppellation relationship present
- ✅ CustodianAppellation → CustodianName inverse present
- ❌ No direct Custodian → Appellation link (correct by design!)

---

## Documentation Generated

1. ✅ `APPELLATION_REFACTORING_PHASE2_20251122.md` - Complete Phase 2 technical documentation
2. ✅ `SESSION_COMPLETE_20251122_APPELLATION_PHASE2.md` - This summary

---

## Next Actions (TODO)

### Critical for v0.2.0 Release
- [ ] Create data migration script (`scripts/migrate_appellations_phase2.py`)
- [ ] Update README.md with new architecture diagrams
- [ ] Update SCHEMA_MODULES.md with alternative_names/variant_of_name documentation
- [ ] Create unit tests for new relationships

### Future Enhancements
- [ ] Add language-tagged appellations (`@lang` support)
- [ ] Track appellation provenance (source, temporal validity)
- [ ] Authority control integration (VIAF, ISNI)

---

## Related Sessions

| Session | Date | Focus | Status |
|---------|------|-------|--------|
| Legal Entity Refactoring | 2025-11-22 AM | Add comprehensive legal entity model | ✅ Complete |
| Phase 1: Appellation/Identifier | 2025-11-22 AM | Connect orphaned classes to Custodian | ✅ Complete |
| **Phase 2: SKOS Alignment** | **2025-11-22 PM** | **Move appellations to CustodianName** | **✅ Complete** |

---

## Session Handoff

**Current State**: Schema is validated and RDF outputs generated. Ready for data migration.

**For Next Agent**:
1. **If continuing refactoring**: Review `APPELLATION_REFACTORING_PHASE2_20251122.md` for complete technical details
2. **If creating migration script**: Convert `Custodian.appellations` → `CustodianName.alternative_names`
3. **If updating docs**: Use generated ER diagram to update architecture visualizations

**Key Files**:
- Main schema: `schemas/20251121/linkml/01_custodian_name_modular.yaml`
- Phase 2 docs: `APPELLATION_REFACTORING_PHASE2_20251122.md`
- Phase 1 docs: `APPELLATION_IDENTIFIER_REFACTORING_20251122.md`

---

**Session End Time**: 2025-11-22, 18:12 UTC  
**Total Duration**: ~45 minutes  
**Files Modified**: 7 (6 schema + 1 main)  
**Files Generated**: 5 (4 RDF + 1 UML)  
**Status**: ✅ READY FOR NEXT PHASE