# Implementation Phases

A recommended implementation order based on the dependency graph across all stories and setup tasks.

## Phase 0: Project Infrastructure

All setup tasks must complete before any user story work begins. T-3 can run in parallel with Phase 1.

| Order | Task | Depends on | Notes |
|-------|------|------------|-------|
| 1 | T-1: Initialize monorepo structure | — | Scaffolds empty backend + frontend projects |
| 2 | T-2: Deployment setup (Dockerfile + config) | T-1 | Docker build, DB connection, health check |
| 2* | T-5: API-first tooling setup | T-1 | OpenAPI spec, codegen plugins, generated types — parallelizable with T-2 |
| 3 | T-4: Development infrastructure | T-2, T-5 | Migrations, router, test infra — gates all user stories |
| 3* | T-3: CI/CD pipeline | T-1, T-2 | Parallelizable with T-4. Uses Gitea Actions (per Q-5 resolution) |

## Phase 1: Core Event Flow (Vertical Slice)

The end-to-end journey from creating an event to viewing it to RSVPing. US-1 is the "Durchstich" that bootstraps the full stack (DB table, backend endpoint, frontend form, localStorage, routing). It will take significantly longer than subsequent stories.

| Order | Story | Depends on | Parallelizable |
|-------|-------|------------|----------------|
| 1 | US-1: Create an event | T-4 | — |
| 2 | US-2: View event landing page | US-1 | — |
| 3 | US-3: RSVP to an event | US-2 | — |

These three stories are strictly sequential. No parallelization within this phase.

## Phase 2: Organizer Management & Event Lifecycle

All stories in this phase depend on US-1 (and T-4 transitively). They can be implemented in parallel since they are independent of each other. Some are more useful after Phase 1 completes (e.g. US-4 needs RSVPs to manage), but they are structurally implementable after US-1.

| Story | Depends on | Notes |
|-------|------------|-------|
| US-4: Manage guest list | US-1 | Most useful after US-3 provides RSVPs to manage |
| US-5: Edit event details | US-1 | Required by US-9 in Phase 3 |
| US-18: Cancel an event | US-1 | Enables deferred ACs in US-2, US-3, US-8 |
| US-19: Delete an event | US-1 | Enables deferred AC in US-2 |
| US-12: Automatic data deletion after expiry | US-1 | Enables deferred AC in US-2; server-side scheduled job |
| US-13: Limit active events | US-1 | Server-side config; independent of all other stories |

**Recommended order within phase:** US-5, US-4, US-18, US-19, US-12, US-13 — starting with US-5 because US-9 (Phase 3) depends on it, and US-4 because it completes the organizer toolset around RSVPs.

## Phase 3: Enhanced Event Page Features

Features that enrich the event page for guests. Most depend on US-2 (event page exists). US-9 additionally requires US-5 (editing). US-10b requires US-10a.

| Story | Depends on | Parallelizable with |
|-------|------------|---------------------|
| US-6: Bookmark an event | US-2 | US-8, US-10a, US-11 |
| US-8: Add event to calendar (.ics / webcal) | US-2 | US-6, US-10a, US-11 |
| US-9: Highlight changed event details | US-2, US-5 | US-6, US-8, US-10a, US-11 (if US-5 is done) |
| US-10a: Post update messages | US-1, US-2 | US-6, US-8, US-11 |
| US-10b: New-update indicator | US-10a | Must follow US-10a |
| US-11: Generate QR code | US-2 | US-6, US-8, US-10a |

**Recommended order within phase:** US-6, US-8, US-11 (simple, independent), then US-10a → US-10b (sequential pair), then US-9 (requires US-5 from Phase 2).

## Phase 4: Visual Customization

Event-level theming and image selection. Both depend on US-1 and US-2. US-15 and US-16 are independent of each other but share the event creation/editing form surface area, so coordinating them is beneficial.

| Story | Depends on | Notes |
|-------|------------|-------|
| US-15: Choose event color theme | US-1, US-2 | Predefined theme picker in creation/edit forms |
| US-16: Select header image from Unsplash | US-1, US-2 | Optional feature gated by API key config |

**Recommended order:** US-15 first (simpler, no external dependency), then US-16. Consider the interaction between event themes and dark/light mode (US-17) — implement US-17 before or alongside US-15 if possible.

## Phase 5: App Shell & PWA

Client-side infrastructure and app-level UX features. These have no or minimal structural dependencies but are only meaningfully testable after earlier phases provide content and data.

| Story | Depends on | Practically useful after |
|-------|------------|------------------------|
| US-7: Local event overview | None (structural) | US-1, US-3, US-6 populate localStorage |
| US-14: Install as PWA | T-4 (structural) | US-2, US-7 provide pages to cache |
| US-17: Dark/light mode | None (structural) | T-4 provides frontend scaffold |

**Recommended order:** US-17 (can be started early once the frontend scaffold exists — consider implementing alongside Phase 2 or 3), then US-7 (after localStorage-populating stories are available), then US-14 (after the app has real pages and assets).

**Note on US-17 timing:** US-17 is listed in Phase 5 for logical grouping, but it can be implemented as early as Phase 2 since it only needs the frontend scaffold. Implementing it earlier is recommended because US-15 (Phase 4) must consider the interaction between event color themes and dark/light mode. Having dark/light mode in place before US-15 simplifies that work.

## Deferred Acceptance Criteria

Several stories contain ACs that reference features from later phases. These are marked `[deferred until US-X is implemented]` in the story text:

| Story | AC | Deferred until | Phase unlocked |
|-------|-----|---------------|----------------|
| US-2 AC 5 | Cancelled state display | US-18 | Phase 2 |
| US-2 AC 6 | Event not found (expiry deletion) | US-12 | Phase 2 |
| US-2 AC 6 | Event not found (organizer deletion) | US-19 | Phase 2 |
| US-3 AC 11 | RSVP blocked on cancelled event | US-18 | Phase 2 |
| US-8 AC 9 | STATUS:CANCELLED in .ics | US-18 | Phase 2 |
| US-12 AC 2 | Delete stored header images | US-16 | Phase 4 |

Once the referenced story is implemented, revisit the deferring story to activate the deferred AC.

## Dependency Graph

Render this diagram at [mermaid.live](https://mermaid.live) or view it directly in Gitea (which renders `mermaid` blocks natively).

```mermaid
graph TD
    classDef infra fill:#4a90d9,stroke:#2c5f8a,color:#fff
    classDef core fill:#e8a838,stroke:#b07c1e,color:#fff
    classDef organizer fill:#50b86c,stroke:#2d8043,color:#fff
    classDef enhanced fill:#9b59b6,stroke:#6c3483,color:#fff
    classDef visual fill:#e74c3c,stroke:#a93226,color:#fff
    classDef shell fill:#7f8c8d,stroke:#566566,color:#fff

    %% Phase 0: Infrastructure
    T1(["T-1: Monorepo"]):::infra --> T2(["T-2: Docker & DB"]):::infra
    T1 --> T5(["T-5: API-First Tooling"]):::infra
    T2 --> T4(["T-4: Dev Infra"]):::infra
    T5 --> T4
    T2 --> T3(["T-3: CI/CD"]):::infra

    %% Phase 1: Core Event Flow
    T4 --> US1["US-1: Create Event"]:::core
    US1 --> US2["US-2: View Event"]:::core
    US2 --> US3["US-3: RSVP"]:::core

    %% Phase 2: Organizer & Lifecycle (branch from US-1)
    US1 --> US4["US-4: Guest List"]:::organizer
    US1 --> US5["US-5: Edit Event"]:::organizer
    US1 --> US18["US-18: Cancel"]:::organizer
    US1 --> US19["US-19: Delete"]:::organizer
    US1 --> US12["US-12: Auto-Cleanup"]:::organizer
    US1 --> US13["US-13: Event Limit"]:::organizer

    %% Phase 3: Enhanced Features (branch from US-2)
    US2 --> US6["US-6: Bookmark"]:::enhanced
    US2 --> US8["US-8: Calendar .ics"]:::enhanced
    US2 --> US10a["US-10a: Messages"]:::enhanced
    US2 --> US11["US-11: QR Code"]:::enhanced
    US5 --> US9["US-9: Change Highlights"]:::enhanced
    US2 --> US9
    US10a --> US10b["US-10b: New-Update Badge"]:::enhanced

    %% Phase 4: Visual Customization (branch from US-2)
    US2 --> US15["US-15: Color Themes"]:::visual
    US2 --> US16["US-16: Unsplash Images"]:::visual

    %% Phase 5: App Shell & PWA
    T4 --> US14["US-14: PWA"]:::shell
    US7["US-7: Local Overview"]:::shell
    US17["US-17: Dark/Light Mode"]:::shell
```

**Legend:**
- 🔵 Infrastructure (T-1 – T-5)
- 🟠 Core Event Flow (US-1 – US-3)
- 🟢 Organizer & Lifecycle (US-4, US-5, US-12, US-13, US-18, US-19)
- 🟣 Enhanced Features (US-6, US-8 – US-11)
- 🔴 Visual Customization (US-15, US-16)
- ⚪ App Shell & PWA (US-7, US-14, US-17)

US-7 and US-17 appear as isolated nodes — they have no structural dependencies but are only practically useful after earlier phases provide content (see Phase 5 notes above).