# Research: Migration UI Improvements

**Date**: 2025-12-27 | **Status**: Complete

## Overview

This research phase was conducted to resolve any technical unknowns and validate design decisions for the Migration UI Improvements feature. Based on the feature specification and existing codebase analysis, all major technical questions have been addressed in the specification's "Clarifications" section.

## Research Findings

### 1. Task History and Status Display

**Decision**: Implement a task history API endpoint and UI component

**Rationale**: 
- The existing `TaskManager` already tracks tasks in memory
- Need to expose this information through a new API endpoint
- UI will display tasks with status, start time, and actions

**Alternatives considered**:
- Full database persistence for all tasks (rejected due to complexity)
- In-memory only with no persistence (rejected as it wouldn't survive restarts)

**Implementation approach**:
- Extend `TaskManager` to support task history retrieval
- Add `/api/tasks` endpoint for fetching task list
- Create `TaskHistory` Svelte component for display

### 2. Task Log Viewing

**Decision**: Implement log retrieval API and modal viewer

**Rationale**:
- Each task already maintains logs in `LogEntry` format
- Need API endpoint to retrieve logs for specific task ID
- UI modal provides detailed log viewing without page navigation

**Alternatives considered**:
- Separate log page (rejected for poor UX)
- Downloadable log files (rejected as overkill for current needs)

**Implementation approach**:
- Add `/api/tasks/{task_id}/logs` endpoint
- Create `TaskLogViewer` modal component
- Integrate with existing task list

### 3. Database Password Error Handling

**Decision**: Implement interactive password prompt with task pausing

**Rationale**:
- Superset requires database passwords that aren't exported
- Current system fails entirely on missing passwords
- Interactive resolution improves user experience significantly

**Alternatives considered**:
- Pre-migration password collection form (rejected as not all migrations need passwords)
- Automatic retry with default passwords (rejected as insecure)

**Implementation approach**:
- Extend `MigrationPlugin` to detect specific Superset password errors
- Add new task state "AWAITING_INPUT"
- Create `PasswordPrompt` component for user input
- Implement task resumption with provided credentials

### 4. Task Persistence Strategy

**Decision**: Hybrid approach - persist only tasks needing user input

**Rationale**:
- Full persistence adds unnecessary complexity
- Most tasks complete quickly and don't need persistence
- Only tasks awaiting user input need to survive restarts

**Alternatives considered**:
- Full database persistence (rejected due to complexity)
- No persistence (rejected as loses important state)

**Implementation approach**:
- Extend `TaskManager` to persist "AWAITING_INPUT" tasks
- Use SQLite for simple persistence
- Clear completed tasks based on configurable retention

### 5. Error Detection and Pattern Matching

**Decision**: Pattern match on Superset API error responses

**Rationale**:
- Superset returns specific error format for missing passwords
- Pattern: `UNPROCESSABLE ENTITY` 422 with specific JSON body
- Error message contains: "Must provide a password for the database"

**Implementation approach**:
- Enhance error handling in `MigrationPlugin.execute()`
- Detect specific error pattern and transition to "AWAITING_INPUT"
- Include database name in password prompt

## Technical Validation

### Existing Codebase Analysis

**TaskManager** (`backend/src/core/task_manager.py`):
- Already supports task creation and status tracking
- Needs extension for:
  - Task history retrieval
  - New "AWAITING_INPUT" state
  - Selective persistence

**MigrationPlugin** (`backend/src/plugins/migration.py`):
- Handles migration execution
- Needs enhancement for:
  - Error pattern detection
  - Task state transitions
  - Password injection

**API Routes** (`backend/src/api/routes/`):
- Existing structure for REST endpoints
- Needs new endpoints:
  - `GET /tasks` - list tasks
  - `GET /tasks/{id}/logs` - get task logs
  - `POST /tasks/{id}/resume` - resume with input

### Performance Considerations

**Pagination**: Basic limit/offset pagination will be implemented for task history to handle potential growth of task records.

**Real-time Updates**: WebSocket or polling approach for real-time status updates. Given existing WebSocket infrastructure, this will leverage the current system.

**Error Handling**: Robust error handling for:
- Invalid task IDs
- Missing logs
- Password validation failures
- Task resumption errors

## Open Questions (Resolved)

All questions from the specification's "Clarifications" section have been addressed:

1. ✅ **Data retention policy**: Configurable retention period implemented
2. ✅ **Multiple password handling**: Prompt for all missing passwords at once
3. ✅ **Invalid password handling**: Prompt again with error message
4. ✅ **Task persistence**: Hybrid approach for "AWAITING_INPUT" tasks
5. ✅ **Performance requirements**: Basic pagination support

## Recommendations

1. **Implementation Order**:
   - Backend API extensions first
   - Task state management second
   - UI components last

2. **Testing Focus**:
   - Error condition testing for password prompts
   - Task state transition validation
   - Real-time update verification

3. **Future Enhancements**:
   - Advanced filtering for task history
   - Task search functionality
   - Export/import of task history

## Conclusion

The research phase confirms that the proposed feature can be implemented using the existing architecture with targeted extensions. No major technical blockers were identified, and all clarification questions have satisfactory answers. The implementation can proceed to Phase 1: Design & Contracts.