# Implementation Plan: Migration Process and UI Redesign

**Branch**: `001-migration-ui-redesign` | **Date**: 2025-12-20 | **Spec**: [specs/001-migration-ui-redesign/spec.md](specs/001-migration-ui-redesign/spec.md)

## Summary

Redesign the migration process to support environment-based selection and automated database mapping. The technical approach involves using a SQLite database to persist mappings between source and target databases, implementing a fuzzy matching algorithm for empirical suggestions, and intercepting asset definitions during migration to apply these mappings.

## Technical Context

**Language/Version**: Python 3.9+, Node.js 18+  
**Primary Dependencies**: FastAPI, SvelteKit, Tailwind CSS, Pydantic, SQLite  
**Storage**: SQLite (for database mappings and environment metadata)  
**Testing**: pytest (Backend), Vitest/Playwright (Frontend)  
**Target Platform**: Linux server  
**Project Type**: Web application (FastAPI + SvelteKit SPA)  
**Performance Goals**: SC-001: Users can complete a full database mapping for 5+ databases in under 60 seconds.  
**Constraints**: SPA-First Architecture (Constitution Principle I), API-Driven Communication (Constitution Principle II).  
**Scale/Scope**: Support for multiple environments and hundreds of database mappings.

## Constitution Check

*GATE: Must pass before Phase 0 research. Re-check after Phase 1 design.*

| Principle | Status | Notes |
|-----------|--------|-------|
| I. SPA-First Architecture | PASS | SvelteKit will be built as a static SPA and served by FastAPI. |
| II. API-Driven Communication | PASS | All mapping and migration actions will go through FastAPI endpoints. |
| III. Modern Stack Consistency | PASS | Using FastAPI, SvelteKit, and Tailwind CSS. |
| IV. Semantic Protocol Adherence | PASS | Code will include GRACE-Poly anchors and contracts. |

## Project Structure

### Documentation (this feature)

```text
specs/001-migration-ui-redesign/
├── plan.md              # This file
├── research.md          # Phase 0 output
├── data-model.md        # Phase 1 output
├── quickstart.md        # Phase 1 output
├── contracts/           # Phase 1 output
└── tasks.md             # Phase 2 output
```

### Source Code (repository root)

```text
backend/
├── src/
│   ├── api/
│   │   └── routes/
│   │       ├── environments.py  # New: Env selection
│   │       └── mappings.py      # New: DB mapping management
│   ├── core/
│   │   └── migration_engine.py  # Update: DB replacement logic
│   └── models/
│       └── mapping.py           # New: SQLite models
└── tests/

frontend/
├── src/
│   ├── components/
│   │   ├── MappingTable.svelte  # New: DB mapping UI
│   │   └── EnvSelector.svelte   # New: Source/Target selection
│   └── routes/
│       └── migration/           # New: Migration dashboard
└── tests/
```

**Structure Decision**: Web application structure (Option 2) is selected to maintain separation between the FastAPI backend and SvelteKit frontend while adhering to the SPA-first principle.

## Complexity Tracking

> **Fill ONLY if Constitution Check has violations that must be justified**

| Violation | Why Needed | Simpler Alternative Rejected Because |
|-----------|------------|-------------------------------------|
| None | N/A | N/A |