# Progress Log - Direct SNOMED Indication Mapping

## Project Context

This project extends the existing HCD Pathway Analysis application with direct SNOMED code matching from GP records. The previous project (Phases 1-5) established the pre-computed pathway architecture and modern UI. This phase adds:

1. **Diagnosis-based directorate assignment** - Primary method using GP SNOMED codes
2. **Indication-based icicle chart** - New chart type showing Trust → Search_Term → Drug → Pathway

## Key Files Reference

**Existing (reuse these):**
- `data_processing/schema.py` - SQLite schema (add new table)
- `data_processing/diagnosis_lookup.py` - Existing cluster-based lookup (extend with direct SNOMED)
- `data_processing/pathway_pipeline.py` - Pathway processing (add indication type)
- `cli/refresh_pathways.py` - CLI refresh command (add chart type support)
- `pathways_app/pathways_app.py` - Reflex app (add chart type toggle)
- `tools/data.py` - Data transformations including department_identification()

**New data:**
- `data/drug_snomed_mapping_enriched.csv` - 163K rows, 187 Search_Terms, 364 drugs

## Known Patterns

### SNOMED Mapping Structure
The enriched mapping CSV has columns:
- Drug, Indication, TA_ID (from NICE TAs)
- Search_Term (simplified grouping, 187 unique values)
- SNOMEDCode, SNOMEDDescription
- CleanedDrugName, PrimaryDirectorate, AllDirectorates

### Direct SNOMED Lookup Logic
For a patient on drug X:
1. Get all SNOMED codes for that drug from ref_drug_snomed_mapping
2. Query PrimaryCareClinicalCoding for those codes (patient's GP record)
3. If match found → use Search_Term and PrimaryDirectorate from matched row
4. If no match → fall back to department_identification()
5. Use most recent SNOMED code by EventDateTime if multiple matches

### Chart Type Architecture
- `chart_type` column in pathway_nodes: "directory" or "indication"
- 12 total pathway datasets: 6 date filters × 2 chart types
- Indication chart: mixed labels (Search_Term for matched, Directorate for unmatched)

### Date Filter Combinations
| ID | Initiated | Last Seen | Default |
|----|-----------|-----------|---------|
| `all_6mo` | All years | Last 6 months | Yes |
| `all_12mo` | All years | Last 12 months | No |
| `1yr_6mo` | Last 1 year | Last 6 months | No |
| `1yr_12mo` | Last 1 year | Last 12 months | No |
| `2yr_6mo` | Last 2 years | Last 6 months | No |
| `2yr_12mo` | Last 2 years | Last 12 months | No |

### Expected Volumes
- SNOMED mapping: 163K rows
- Search_Terms: 187 unique
- Pathway nodes per date filter: ~300 (directory), ~400-600 (indication)

---

## Iteration Log

## Iteration 1 — 2026-02-05
### Task: 1.1 Create SQLite Table for SNOMED Mapping
### Why this task:
- First task in Phase 1 (Data Infrastructure) — all other phases depend on having the data layer in place
- No external dependencies — pure schema definition work
- Follows "data infrastructure first" principle
### Status: COMPLETE
### What was done:
- Added `REF_DRUG_SNOMED_MAPPING_SCHEMA` to `data_processing/schema.py` with 11 columns:
  - id, drug_name, indication, ta_id, search_term, snomed_code, snomed_description
  - cleaned_drug_name, primary_directorate, all_directorates, created_at
- Added 5 custom indexes for lookup performance:
  - idx_ref_drug_snomed_mapping_drug (drug_name)
  - idx_ref_drug_snomed_mapping_cleaned (cleaned_drug_name)
  - idx_ref_drug_snomed_mapping_snomed (snomed_code)
  - idx_ref_drug_snomed_mapping_search_term (search_term)
  - idx_ref_drug_snomed_mapping_drug_snomed (composite: cleaned_drug_name, snomed_code)
- Added `create_drug_snomed_mapping_table()` helper function
- Added schema to `REFERENCE_TABLES_SCHEMA` (included in `ALL_TABLES_SCHEMA`)
- Updated helper functions to include new table:
  - `drop_reference_tables()` — drops new table
  - `get_reference_table_counts()` — counts new table (with try/except for safety)
  - `verify_reference_tables_exist()` — checks for new table
### Validation results:
- Tier 1 (Code): `python -m py_compile data_processing/schema.py` — PASSED
- Tier 1 (Code): Import check — PASSED
- Tier 2 (Data): Migration created table with 0 rows — PASSED
- Tier 2 (Data): All 11 columns and 6 indexes present — PASSED
### Files changed:
- `data_processing/schema.py` — added schema, updated helpers
### Committed: cf35937 "feat: add ref_drug_snomed_mapping schema (Task 1.1)"
### Patterns discovered:
- Existing schema pattern: CREATE TABLE + CREATE INDEX in single SQL string
- Helper functions follow consistent pattern: create, drop, get_counts, verify_exists
- `get_reference_table_counts` needed try/except for tables that might not exist yet
### Next iteration should:
- Start Task 1.2: Create `data_processing/load_snomed_mapping.py` script to load the CSV
- The CSV has columns: Drug, Indication, TA_ID, Search_Term, SNOMEDCode, SNOMEDDescription, CleanedDrugName, PrimaryDirectorate, AllDirectorates
- Note: SNOMEDCode in CSV has `.0` suffix (e.g., "156370009.0") — may need cleanup
### Blocked items:
- None