# Implementation Plan: [FEATURE]

**Branch**: `[###-feature-name]` | **Date**: [DATE] | **Spec**: [link]
**Input**: Feature specification from `/specs/[###-feature-name]/spec.md`

**Note**: This template is filled in by the `/speckit.plan` command. See `.specify/templates/commands/plan.md` for the execution workflow.

## Summary

[Extract from feature spec: primary requirement + technical approach from research]

## Technical Context

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  ACTION REQUIRED: Replace the content in this section with the technical details
  for the project. The structure here is presented in advisory capacity to guide
  the iteration process.
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**Language/Version**: Python 3.11  
**Primary Dependencies**: FastAPI, pandas, numpy, scipy, matplotlib, fitparse, tcxparser, gpxpy  
**Storage**: PostgreSQL (for user data and analysis results)  
**Testing**: pytest  
**Target Platform**: Linux server  
**Project Type**: web  
**Performance Goals**: Analysis of a typical 2-hour workout file MUST complete in under 30 seconds; processing a batch of 100 workout files concurrently without generating errors or significant performance degradation.  
**Constraints**: Public API (no authentication); errors reported as JSON objects; best effort service availability.  
**Scale/Scope**: Batch analysis of up to 100 workout files concurrently; configurable FTP per user account.

## Constitution Check

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

| Principle | Status | Justification (if violation) |
|---|---|---|
| I. Library-First | Aligned | Core analysis logic will be implemented as a reusable library. |
| II. CLI Interface | VIOLATION | The primary interface is an API, not a CLI. Justification: The feature is designed as a web service with API endpoints for integration. A CLI could be added later if needed for specific use cases, but it's not the primary requirement for this feature. |
| III. Test-First (NON-NEGOTIABLE) | Aligned | User scenarios and acceptance criteria are defined, supporting a test-first approach. |
| IV. Integration Testing | Aligned | API endpoints and batch processing necessitate integration tests. |
| V. Observability | Aligned | Error reporting and service availability imply the need for observability. |
| VI. Versioning & Breaking Changes | Aligned | Will consider API versioning as part of the design. |
| VII. Simplicity | Aligned | Focus on core analysis functionality. |

## Project Structure

### Documentation (this feature)

```
specs/[###-feature]/
├── 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)

```
src/
├── core/
│   ├── batch_processor.py
│   ├── chart_generator.py
│   ├── file_parser.py
│   ├── logger.py
│   ├── report_generator.py
│   ├── workout_analyzer.py
│   └── workout_data.py
├── db/
│   ├── models.py
│   └── session.py
└── utils/
    └── zone_calculator.py

api/
├── routers/
│   └── analysis.py
├── main.py
└── schemas.py

tests/
├── unit/
│   ├── test_batch_processor.py
│   ├── test_chart_generator.py
│   ├── test_fit_parser.py
│   ├── test_gpx_parser.py
│   ├── test_tcx_parser.py
│   └── test_workout_data.py
├── integration/
└── contract/
    ├── test_analyze_workout_api.py
    ├── test_batch_analysis_api.py
    └── test_charts_api.py
├── performance/
│   └── test_performance.py
```

**Structure Decision**: The project will use a `src/` directory for core logic, `api/` for the FastAPI application, and `tests/` for all testing types. This aligns with a modular web application structure.

## Complexity Tracking

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

| Violation | Why Needed | Simpler Alternative Rejected Because |
|-----------|------------|-------------------------------------|
| [e.g., 4th project] | [current need] | [why 3 projects insufficient] |
| [e.g., Repository pattern] | [specific problem] | [why direct DB access insufficient] |