# Implementation Tasks - OAuth 2.0 Email Support

## Status Overview

**Final Status**: Production-Ready (2026-02-10)
**Requirements Coverage**: 35/37 (95%)

## Completed Tasks

### Phase A: Critical Production Requirements (3 tasks)

- [x] 1. Retry logic with exponential backoff (1s, 2s, 4s) - Req: 5.1, 5.2
- [x] 2. Failed email storage after retry exhaustion - Req: 5.3
- [x] 3. Enhanced OAuth 2.0 error logging - Req: 5.4, 5.7

Session 2 additional fixes:
- Credential validation changed to falsy check (nodemailer XOAuth2 compatibility)
- PUT handler preserves secrets when empty values submitted
- Config types changed to `NonBlankString | undefined`
- GET response returns `undefined` for secrets
- Browser autofill prevention (`autoComplete="new-password"`)
- Static IDs replaced with `useId()` hook (Biome lint compliance)

### Baseline Implementation (12 tasks)

- [x] Configuration schema (4 config keys, encryption, NonBlankString types) - Req: 1.1, 1.5, 6.1
- [x] OAuth 2.0 transport creation (nodemailer Gmail service) - Req: 2.1, 2.2, 3.1-3.3, 3.5, 6.2
- [x] Service initialization and token management (S2S integration) - Req: 2.3, 2.5, 2.6, 3.6, 5.6, 6.2, 6.4
- [x] API validation and persistence (PUT/GET endpoints) - Req: 1.3, 1.4, 1.5, 1.6, 5.5, 6.5
- [x] Field-specific validation error messages - Req: 1.7
- [x] OAuth2Setting UI component (react-hook-form integration) - Req: 1.2, 4.1
- [x] AdminAppContainer state management (4 state properties) - Req: 4.2, 6.3
- [x] Mail settings form submission - Req: 1.3, 1.6, 1.7
- [x] Transmission method selection ('oauth2' option) - Req: 1.1, 1.2
- [x] Multi-language translations (en, ja, fr, ko, zh) - Req: 1.2, 4.1, 4.3

## Not Implemented (Optional Enhancements)

- Help text for 2 of 4 fields incomplete (Req 4.3)
- Credential field masking in UI (Req 4.4)
- Test email button for OAuth 2.0 (Req 4.5)