feat: integrate SvelteKit for seamless navigation and improved data loading

specs/004-integrate-svelte-kit/plan.md

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+# Implementation Plan: Integrate SvelteKit
+
+**Branch**: `004-integrate-svelte-kit` | **Date**: 2025-12-20 | **Spec**: [specs/004-integrate-svelte-kit/spec.md](specs/004-integrate-svelte-kit/spec.md)
+**Input**: Feature specification from `/specs/004-integrate-svelte-kit/spec.md`
+
+## Summary
+
+Integrate SvelteKit as the primary frontend framework to provide seamless navigation, improved data loading, and a unified layout. The application will be configured as a Static Single Page Application (SPA) to be served by the existing Python backend, preserving all existing functionality while leveraging modern framework features like file-based routing and shared layouts.
+
+## Technical Context
+
+**Language/Version**: Python 3.9+, Node.js 18+  
+**Primary Dependencies**: SvelteKit, FastAPI, Tailwind CSS (inferred from existing frontend)  
+**Storage**: N/A (Frontend integration)  
+**Testing**: pytest (Backend), Vitest/Playwright (Frontend - SvelteKit defaults)  
+**Target Platform**: Linux server (SPA served by backend)
+**Project Type**: Web application (frontend + backend)  
+**Performance Goals**: Page transition time < 200ms (SC-001)  
+**Constraints**: Must be deployable as a Static SPA (FR-003), no Node.js server in production (Assumptions)  
+**Scale/Scope**: Migration of existing Dashboard and Settings pages
+
+## Constitution Check
+
+*GATE: Must pass before Phase 0 research. Re-check after Phase 1 design.*
+
+- **Principle Compliance**: The project constitution is currently in a template state. No specific violations identified.
+- **Architecture Alignment**: The move to SvelteKit aligns with the goal of using modern frontend patterns while maintaining the "SPA served by backend" constraint.
+
+## Project Structure
+
+### Documentation (this feature)
+
+```text
+specs/004-integrate-svelte-kit/
+├── plan.md              # This file (/speckit.plan command output)
+├── research.md          # Phase 0 output (/speckit.plan command)
+├── data-model.md        # Phase 1 output (/speckit.plan command)
+├── quickstart.md        # Phase 1 output (/speckit.plan command)
+├── contracts/           # Phase 1 output (/speckit.plan command)
+└── tasks.md             # Phase 2 output (/speckit.tasks command - NOT created by /speckit.plan)
+```
+
+### Source Code (repository root)
+
+```text
+backend/
+├── src/
+│   ├── models/
+│   ├── services/
+│   └── api/
+└── tests/
+
+frontend/
+├── src/
+│   ├── lib/
+│   ├── routes/          # SvelteKit file-based routing
+│   └── app.html
+├── static/
+└── tests/
+```
+
+**Structure Decision**: Option 2: Web application. The project already has `backend/` and `frontend/` directories. SvelteKit will be integrated into the `frontend/` directory, replacing the current Svelte setup.
+
+## 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 |