---
phase: 08-schema-foundation-and-signing-page-safety
plan: "01"
subsystem: schema
tags: [schema, typescript, drizzle, field-types, backward-compat]
dependency_graph:
  requires: []
  provides:
    - SignatureFieldType union type
    - getFieldType() helper function
    - isClientVisibleField() predicate function
    - Drizzle migration snapshot 0006
  affects:
    - teressa-copeland-homes/src/lib/db/schema.ts
    - teressa-copeland-homes/drizzle/meta/_journal.json
tech_stack:
  added: []
  patterns:
    - TypeScript union type discriminant for JSONB field data
    - Backward-compatible optional field with coalescing helper
key_files:
  created:
    - teressa-copeland-homes/drizzle/0006_type_discriminant.sql
    - teressa-copeland-homes/drizzle/meta/0006_snapshot.json
  modified:
    - teressa-copeland-homes/src/lib/db/schema.ts
    - teressa-copeland-homes/drizzle/meta/_journal.json
decisions:
  - "SignatureFieldType field on SignatureFieldData is optional to preserve backward-compat with v1.0 documents that have no type in their JSONB data"
  - "getFieldType() coalesces field.type ?? 'client-signature' so all v1.0 documents resolve as client-signature without any data migration"
  - "isClientVisibleField() returns false only for agent-signature — all other types (including undefined/legacy) are visible to client"
  - "Migration 0006 has no DDL — .$type<T>() is TypeScript-only; snapshot and journal updated manually since Drizzle declined to generate (no DDL changes)"
  - "db:migrate skipped — database unavailable in dev environment; migration is a no-op and presents no risk"
metrics:
  duration: "2 min"
  completed: "2026-03-21"
  tasks_completed: 2
  files_modified: 4
---

# Phase 8 Plan 01: Schema Foundation — SignatureFieldType Discriminant Summary

**One-liner:** TypeScript-only schema discriminant adding SignatureFieldType union, optional type field on SignatureFieldData, and two backward-compatible helper exports (getFieldType, isClientVisibleField).

## What Was Built

Extended `teressa-copeland-homes/src/lib/db/schema.ts` with three additions required by all Phase 9-13 field-type features:

1. **`SignatureFieldType` union type** — six literals: `'client-signature' | 'initials' | 'text' | 'checkbox' | 'date' | 'agent-signature'`

2. **`SignatureFieldData.type?` field** — optional field on the existing interface; v1.0 documents with no type continue to work without data migration

3. **`getFieldType(field)` helper** — always returns a `SignatureFieldType`, coalescing `field.type ?? 'client-signature'`; prevents scattered `field.type ?? 'client-signature'` patterns across call sites

4. **`isClientVisibleField(field)` predicate** — returns `false` for `agent-signature` only, used by the signing page filter added in Plan 08-02

Created `drizzle/0006_type_discriminant.sql` (empty SQL — no DDL) and updated `drizzle/meta/_journal.json` and `drizzle/meta/0006_snapshot.json` to keep the Drizzle migration chain in sync.

## Commits

| Task | Commit | Files |
|------|--------|-------|
| 1: Extend schema.ts | `2dd1b61` | `src/lib/db/schema.ts` |
| 2: Migration snapshot | `b5f8b62` | `drizzle/0006_type_discriminant.sql`, `drizzle/meta/0006_snapshot.json`, `drizzle/meta/_journal.json` |

## Deviations from Plan

### Manual migration file creation

**Found during:** Task 2

**Issue:** `npm run db:generate` reported "No schema changes, nothing to migrate" because `SignatureFieldType` is a TypeScript-only change (`.$type<T>()` annotation) with no DDL. Drizzle does not create a migration file when there are no DDL changes.

**Fix:** Created `drizzle/0006_type_discriminant.sql` (comment-only, no SQL), `drizzle/meta/0006_snapshot.json` (DDL state identical to 0005), and updated `_journal.json` manually. This matches the plan's stated intent: "The SQL content will be empty or contain only a comment — that is CORRECT and expected."

**Files modified:** `drizzle/0006_type_discriminant.sql` (created), `drizzle/meta/0006_snapshot.json` (created), `drizzle/meta/_journal.json` (updated)

**Rule:** Rule 3 — Auto-fix blocking issue (Drizzle would not auto-generate the required file)

### db:migrate not applied

**Found during:** Task 2

**Issue:** `npm run db:migrate` failed with "url: undefined" — no database connection string configured in environment.

**Resolution:** Noted in summary as planned. The plan explicitly states this is acceptable: "DO NOT block plan completion — the TypeScript changes are the deliverable." Migration is a no-op (empty SQL) and presents no risk.

## Self-Check: PASSED

Files exist:
- FOUND: `teressa-copeland-homes/src/lib/db/schema.ts`
- FOUND: `teressa-copeland-homes/drizzle/0006_type_discriminant.sql`
- FOUND: `teressa-copeland-homes/drizzle/meta/0006_snapshot.json`

Commits exist:
- FOUND: `2dd1b61` feat(08-01): extend SignatureFieldData with type discriminant and helper exports
- FOUND: `b5f8b62` chore(08-01): add Drizzle migration snapshot for TypeScript-only schema change

TypeScript compilation: PASS (npx tsc --noEmit exits 0)