feat: Add project foundation, documentation, and Docker setup

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>
2026-01-19 19:49:47 +01:00
commit a59ef0f3f5
10 changed files with 1020 additions and 0 deletions
--- a/README.md
+++ b/README.md
@@ -0,0 +1,228 @@
+# Training Tracker
+
+A mobile-friendly web application for tracking training activities with a Go backend and PostgreSQL database.
+
+## Project Structure
+
+```
+training-tracker/
+├── backend/
+│   ├── cmd/server/         # Application entry point
+│   ├── internal/
+│   │   ├── api/            # HTTP handlers
+│   │   ├── models/         # Data structures
+│   │   └── storage/        # Database layer
+│   ├── Dockerfile.dev      # Development container
+│   ├── Dockerfile.prod     # Production container
+│   ├── go.mod
+│   └── go.sum
+├── frontend/
+│   ├── index.html
+│   ├── css/styles.css
+│   └── js/
+│       ├── api.js          # API client
+│       └── app.js          # Application logic
+├── .gitea/workflows/       # CI/CD pipelines
+├── docker-compose.yml
+└── README.md
+```
+
+## Prerequisites
+
+- Docker and Docker Compose
+- Go 1.25.6+ (for local development without Docker)
+- A web server or `python3 -m http.server` (for frontend)
+
+## Running with Docker Compose (Recommended)
+
+Start PostgreSQL and the backend:
+
+```bash
+docker-compose up -d
+```
+
+This starts:
+- PostgreSQL on port 5432
+- Backend API on port 8080
+
+To view logs:
+
+```bash
+docker-compose logs -f backend
+```
+
+To stop:
+
+```bash
+docker-compose down
+```
+
+## Running Manually
+
+### 1. Start PostgreSQL
+
+```bash
+docker-compose up -d postgres
+```
+
+Or use an existing PostgreSQL instance and set environment variables.
+
+### 2. Run the Backend
+
+```bash
+cd backend
+export DB_HOST=localhost
+export DB_PORT=5432
+export DB_USER=postgres
+export DB_PASSWORD=postgres
+export DB_NAME=training_tracker
+go run ./cmd/server
+```
+
+### 3. Serve the Frontend
+
+```bash
+cd frontend
+python3 -m http.server 3000
+```
+
+Open http://localhost:3000 in your browser.
+
+## Testing
+
+The backend includes comprehensive unit and integration tests.
+
+### Run Unit Tests
+
+```bash
+cd backend
+go test ./...
+```
+
+### Run Tests with Coverage
+
+```bash
+cd backend
+go test -cover ./...
+```
+
+### Run Integration Tests
+
+Integration tests use testcontainers to spin up a PostgreSQL instance. Docker must be running.
+
+```bash
+cd backend
+go test -v -tags=integration ./internal/storage/...
+```
+
+### Run All Tests
+
+```bash
+cd backend
+go test ./... && go test -tags=integration ./internal/storage/...
+```
+
+## Environment Variables
+
+| Variable | Default | Description |
+|----------|---------|-------------|
+| `DB_HOST` | localhost | PostgreSQL host |
+| `DB_PORT` | 5432 | PostgreSQL port |
+| `DB_USER` | postgres | Database user |
+| `DB_PASSWORD` | postgres | Database password |
+| `DB_NAME` | training_tracker | Database name |
+| `PORT` | 8080 | Backend server port |
+
+## API Endpoints
+
+### Exercises
+
+| Method | Endpoint | Description |
+|--------|----------|-------------|
+| GET | `/api/exercises` | List all exercises |
+| POST | `/api/exercises` | Create exercise |
+| GET | `/api/exercises/:id` | Get exercise by ID |
+| PUT | `/api/exercises/:id` | Update exercise |
+| DELETE | `/api/exercises/:id` | Delete exercise |
+
+### Training Plans
+
+| Method | Endpoint | Description |
+|--------|----------|-------------|
+| GET | `/api/plans` | List all plans |
+| POST | `/api/plans` | Create plan |
+| GET | `/api/plans/:id` | Get plan with exercises |
+| PUT | `/api/plans/:id` | Update plan |
+| DELETE | `/api/plans/:id` | Delete plan |
+
+### Sessions
+
+| Method | Endpoint | Description |
+|--------|----------|-------------|
+| GET | `/api/sessions` | List all sessions |
+| POST | `/api/sessions` | Create session |
+| GET | `/api/sessions/:id` | Get session with entries |
+| PUT | `/api/sessions/:id` | Update session |
+| DELETE | `/api/sessions/:id` | Delete session |
+| POST | `/api/sessions/:id/entries` | Add exercise entry |
+
+### Health Check
+
+| Method | Endpoint | Description |
+|--------|----------|-------------|
+| GET | `/api/health` | Returns `{"status": "ok"}` |
+
+## API Examples
+
+### Create an Exercise
+
+```bash
+curl -X POST http://localhost:8080/api/exercises \
+  -H "Content-Type: application/json" \
+  -d '{"name": "Bench Press", "type": "strength", "muscle_group": "Chest"}'
+```
+
+### Create a Session
+
+```bash
+curl -X POST http://localhost:8080/api/sessions \
+  -H "Content-Type: application/json" \
+  -d '{"date": "2026-01-19T10:00:00Z", "notes": "Morning workout"}'
+```
+
+### Add Entry to Session
+
+```bash
+curl -X POST http://localhost:8080/api/sessions/1/entries \
+  -H "Content-Type: application/json" \
+  -d '{"exercise_id": 1, "weight": 80, "sets_completed": 3, "reps": 10}'
+```
+
+## Features
+
+- Mobile-first responsive design
+- Exercise library (strength and cardio types)
+- Training plan templates
+- Session logging with:
+  - Strength: weight, sets, reps
+  - Cardio: duration, distance, heart rate
+- Session history and dashboard
+
+## Production Deployment
+
+Build the production image:
+
+```bash
+docker build -f backend/Dockerfile.prod -t training-tracker-backend ./backend
+```
+
+The production image uses:
+- Distroless base image
+- Non-root user
+- Pinned image digests for reproducibility
+
+## CI/CD
+
+The project includes a Gitea Actions workflow (`.gitea/workflows/ci.yaml`) that:
+1. Runs tests on pull requests
+2. Builds and pushes Docker images on merge to main
--- a/backend/Dockerfile.dev
+++ b/backend/Dockerfile.dev
@@ -0,0 +1,18 @@
+FROM golang:1.25.6-bookworm
+
+WORKDIR /app
+
+RUN apt-get update && apt-get install -y --no-install-recommends \
+    git \
+    && rm -rf /var/lib/apt/lists/*
+
+COPY go.mod go.sum ./
+RUN go mod download
+
+COPY . .
+
+RUN go build -o server ./cmd/server
+
+EXPOSE 8080
+
+CMD ["./server"]
--- a/backend/Dockerfile.prod
+++ b/backend/Dockerfile.prod
@@ -0,0 +1,22 @@
+# Production Dockerfile with pinned image digests
+# golang:1.25.6-alpine
+FROM golang@sha256:d9b2e14101f27ec8d09674cd01186798d227bb0daec90e032aeb1cd22ac0f029 AS builder
+
+WORKDIR /app
+
+COPY go.mod go.sum ./
+RUN go mod download
+
+COPY . .
+RUN CGO_ENABLED=0 GOOS=linux go build -ldflags="-s -w" -o server ./cmd/server
+
+# gcr.io/distroless/static-debian12:nonroot
+FROM gcr.io/distroless/static-debian12@sha256:6dcc833df2a475be1a3d7fc951de90ac91a2cb0be237c7578b88722571f77571
+
+COPY --from=builder /app/server /server
+
+USER nonroot:nonroot
+
+EXPOSE 8080
+
+ENTRYPOINT ["/server"]
--- a/backend/claude.md
+++ b/backend/claude.md
@@ -0,0 +1,116 @@
+## General
+- Before scaffolding any service, verify current stable versions from official sources (go.dev, rust-lang.org, nodejs.org, etc.)
+- Prefer stdlib over dependencies where reasonable
+- No vendoring unless explicitly requested
+
+## Go
+- Use latest stable Go version (check https://go.dev/dl/ before starting)
+- Use `slog` for structured logging
+- `context.Context` first param, always
+- No `init()` unless unavoidable
+- Errors: prefer `errors.Join` for multiple errors, `fmt.Errorf` with `%w` for wrapping
+
+## Containers
+- Multi-stage builds, distroless/scratch final images
+- ubuntu based images for the development builds
+- Non-root user, read-only rootfs for production builds
+- prepare dockerfiles for both development and production
+- Pin base image digests in prod Dockerfiles
+
+## K8s Manifests
+- Always include resource requests/limits
+- Liveness/readiness probes with sane defaults
+- PodDisruptionBudgets for replicated workloads
+
+## Code Style
+- Fail fast, return early
+- Table-driven tests
+- No obvious comments
+
+## CI/CD
+- Git remote: Gitea at https://[gitea.yourdomain.com](https://gitea.home.hrajfrisbee.cz/)
+- CI: Gitea Actions (workflow syntax is GitHub Actions compatible)
+- Workflows go in `.gitea/workflows/`
+- Use `runs-on: linux-amd64` (or whatever labels your runners have)
+- Registry: gitea.home.hrajfrisbee.cz (use `${{ secrets.REGISTRY_TOKEN }}` for auth)
+
+## Testing (Go)
+
+### Go Test Requirements
+- **MANDATORY: All new Go code must have corresponding tests**
+- Use stdlib `testing` package, no testify unless already in project
+- Table-driven tests as default pattern
+- Test file next to source: `foo.go` → `foo_test.go`
+- Name tests `Test<Function>_<scenario>` (e.g., `TestCreateUser_duplicateEmail`)
+- Use `t.Parallel()` where safe
+- Subtests for table entries: `t.Run(tc.name, func(t *testing.T) { ... })`
+- Test behavior, not implementation
+- Use `testing.Short()` to skip slow integration tests: `if testing.Short() { t.Skip() }`
+
+### Test Structure
+- Each test function should test ONE behavior
+- Use descriptive test names: `TestExerciseHandler_Create_ValidInput`
+- Table-driven test format:
+  ```go
+  tests := []struct {
+      name    string
+      input   InputType
+      want    ExpectedType
+      wantErr bool
+  }{
+      {"valid input", validInput, expectedOutput, false},
+      {"empty name", emptyName, nil, true},
+  }
+  for _, tt := range tests {
+      t.Run(tt.name, func(t *testing.T) {
+          // test logic
+      })
+  }
+  ```
+
+### Handler Tests (Unit)
+- Mock external dependencies (repositories, services)
+- Use `httptest.NewRecorder()` and `httptest.NewRequest()`
+- Test: success path, validation errors, not found, internal errors
+- Mock interfaces defined in `internal/api/interfaces.go`
+- Mock implementations in `internal/api/mocks_test.go`
+
+### Repository Tests (Integration)
+- Use testcontainers-go for database tests
+- Integration tests in `_test.go` with build tag `//go:build integration`
+- Clean database state between tests using `truncateTables()`
+- Test: CRUD operations, edge cases, transactions, cascades
+- Test helpers in `internal/storage/testhelpers_test.go`
+
+### What to Test
+- All public functions/methods
+- Happy path AND error paths
+- Edge cases: empty inputs, nil values, not found
+- Validation logic
+- Transaction rollback scenarios
+
+### What NOT to Test
+- Simple getters/setters
+- Third-party library code
+- Private helper functions (test through public API)
+
+### Running Tests
+```bash
+# Run all unit tests (fast)
+go test ./...
+
+# Run with verbose output
+go test -v ./...
+
+# Run with coverage
+go test -cover ./...
+
+# Run only unit tests, skip integration
+go test -short ./...
+
+# Run integration tests (requires Docker)
+go test -v -tags=integration ./internal/storage/...
+
+# Run specific package
+go test -v ./internal/api/...
+```
--- a/backend/go.mod
+++ b/backend/go.mod
@@ -0,0 +1,67 @@
+module training-tracker
+
+go 1.25.6
+
+require (
+	github.com/lib/pq v1.10.9
+	github.com/testcontainers/testcontainers-go v0.40.0
+	github.com/testcontainers/testcontainers-go/modules/postgres v0.40.0
+)
+
+require (
+	dario.cat/mergo v1.0.2 // indirect
+	github.com/Azure/go-ansiterm v0.0.0-20210617225240-d185dfc1b5a1 // indirect
+	github.com/Microsoft/go-winio v0.6.2 // indirect
+	github.com/cenkalti/backoff/v4 v4.3.0 // indirect
+	github.com/containerd/errdefs v1.0.0 // indirect
+	github.com/containerd/errdefs/pkg v0.3.0 // indirect
+	github.com/containerd/log v0.1.0 // indirect
+	github.com/containerd/platforms v0.2.1 // indirect
+	github.com/cpuguy83/dockercfg v0.3.2 // indirect
+	github.com/davecgh/go-spew v1.1.1 // indirect
+	github.com/distribution/reference v0.6.0 // indirect
+	github.com/docker/docker v28.5.1+incompatible // indirect
+	github.com/docker/go-connections v0.6.0 // indirect
+	github.com/docker/go-units v0.5.0 // indirect
+	github.com/ebitengine/purego v0.8.4 // indirect
+	github.com/felixge/httpsnoop v1.0.4 // indirect
+	github.com/go-logr/logr v1.4.3 // indirect
+	github.com/go-logr/stdr v1.2.2 // indirect
+	github.com/go-ole/go-ole v1.2.6 // indirect
+	github.com/google/uuid v1.6.0 // indirect
+	github.com/grpc-ecosystem/grpc-gateway/v2 v2.27.4 // indirect
+	github.com/klauspost/compress v1.18.0 // indirect
+	github.com/lufia/plan9stats v0.0.0-20211012122336-39d0f177ccd0 // indirect
+	github.com/magiconair/properties v1.8.10 // indirect
+	github.com/moby/docker-image-spec v1.3.1 // indirect
+	github.com/moby/go-archive v0.1.0 // indirect
+	github.com/moby/patternmatcher v0.6.0 // indirect
+	github.com/moby/sys/sequential v0.6.0 // indirect
+	github.com/moby/sys/user v0.4.0 // indirect
+	github.com/moby/sys/userns v0.1.0 // indirect
+	github.com/moby/term v0.5.0 // indirect
+	github.com/morikuni/aec v1.0.0 // indirect
+	github.com/opencontainers/go-digest v1.0.0 // indirect
+	github.com/opencontainers/image-spec v1.1.1 // indirect
+	github.com/pkg/errors v0.9.1 // indirect
+	github.com/pmezard/go-difflib v1.0.0 // indirect
+	github.com/power-devops/perfstat v0.0.0-20210106213030-5aafc221ea8c // indirect
+	github.com/shirou/gopsutil/v4 v4.25.6 // indirect
+	github.com/sirupsen/logrus v1.9.3 // indirect
+	github.com/stretchr/testify v1.11.1 // indirect
+	github.com/tklauser/go-sysconf v0.3.12 // indirect
+	github.com/tklauser/numcpus v0.6.1 // indirect
+	github.com/yusufpapurcu/wmi v1.2.4 // indirect
+	go.opentelemetry.io/auto/sdk v1.2.1 // indirect
+	go.opentelemetry.io/contrib/instrumentation/net/http/otelhttp v0.49.0 // indirect
+	go.opentelemetry.io/otel v1.38.0 // indirect
+	go.opentelemetry.io/otel/metric v1.38.0 // indirect
+	go.opentelemetry.io/otel/sdk v1.38.0 // indirect
+	go.opentelemetry.io/otel/trace v1.38.0 // indirect
+	golang.org/x/crypto v0.43.0 // indirect
+	golang.org/x/sys v0.38.0 // indirect
+	golang.org/x/text v0.32.0 // indirect
+	google.golang.org/grpc v1.78.0 // indirect
+	google.golang.org/protobuf v1.36.11 // indirect
+	gopkg.in/yaml.v3 v3.0.1 // indirect
+)
--- a/backend/go.sum
+++ b/backend/go.sum
@@ -0,0 +1,178 @@
+dario.cat/mergo v1.0.2 h1:85+piFYR1tMbRrLcDwR18y4UKJ3aH1Tbzi24VRW1TK8=
+dario.cat/mergo v1.0.2/go.mod h1:E/hbnu0NxMFBjpMIE34DRGLWqDy0g5FuKDhCb31ngxA=
+github.com/AdaLogics/go-fuzz-headers v0.0.0-20240806141605-e8a1dd7889d6 h1:He8afgbRMd7mFxO99hRNu+6tazq8nFF9lIwo9JFroBk=
+github.com/AdaLogics/go-fuzz-headers v0.0.0-20240806141605-e8a1dd7889d6/go.mod h1:8o94RPi1/7XTJvwPpRSzSUedZrtlirdB3r9Z20bi2f8=
+github.com/Azure/go-ansiterm v0.0.0-20210617225240-d185dfc1b5a1 h1:UQHMgLO+TxOElx5B5HZ4hJQsoJ/PvUvKRhJHDQXO8P8=
+github.com/Azure/go-ansiterm v0.0.0-20210617225240-d185dfc1b5a1/go.mod h1:xomTg63KZ2rFqZQzSB4Vz2SUXa1BpHTVz9L5PTmPC4E=
+github.com/Microsoft/go-winio v0.6.2 h1:F2VQgta7ecxGYO8k3ZZz3RS8fVIXVxONVUPlNERoyfY=
+github.com/Microsoft/go-winio v0.6.2/go.mod h1:yd8OoFMLzJbo9gZq8j5qaps8bJ9aShtEA8Ipt1oGCvU=
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+github.com/creack/pty v1.1.18 h1:n56/Zwd5o6whRC5PMGretI4IdRLlmBXYNjScPaBgsbY=
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+gotest.tools/v3 v3.5.2/go.mod h1:LtdLGcnqToBH83WByAAi/wiwSFCArdFIUV/xxN4pcjA=
--- a/docker-compose.yml
+++ b/docker-compose.yml
@@ -0,0 +1,40 @@
+version: '3.8'
+
+services:
+  postgres:
+    image: postgres:15-alpine
+    container_name: training-tracker-db
+    environment:
+      POSTGRES_USER: postgres
+      POSTGRES_PASSWORD: postgres
+      POSTGRES_DB: training_tracker
+    ports:
+      - "5432:5432"
+    volumes:
+      - postgres_data:/var/lib/postgresql/data
+    healthcheck:
+      test: ["CMD-SHELL", "pg_isready -U postgres"]
+      interval: 5s
+      timeout: 5s
+      retries: 5
+
+  backend:
+    build:
+      context: ./backend
+      dockerfile: Dockerfile.dev
+    container_name: training-tracker-backend
+    environment:
+      DB_HOST: postgres
+      DB_PORT: 5432
+      DB_USER: postgres
+      DB_PASSWORD: postgres
+      DB_NAME: training_tracker
+      PORT: 8080
+    ports:
+      - "8080:8080"
+    depends_on:
+      postgres:
+        condition: service_healthy
+
+volumes:
+  postgres_data:
--- a/plans/001-initial-implementation-plan.md
+++ b/plans/001-initial-implementation-plan.md
@@ -0,0 +1,186 @@
+# Training Tracker - Implementation Plan
+
+## Project Overview
+A mobile-friendly web application for tracking training activities with a Golang backend and SQL/NoSQL database.
+
+---
+
+## Phase 1: Project Foundation
+
+### 1.1 Project Structure
+```
+training-tracker/
+├── backend/
+│   ├── cmd/
+│   │   └── server/
+│   │       └── main.go
+│   ├── internal/
+│   │   ├── api/           # HTTP handlers
+│   │   ├── models/        # Data structures
+│   │   ├── storage/       # Database layer
+│   │   └── service/       # Business logic
+│   ├── go.mod
+│   └── go.sum
+├── frontend/
+│   ├── index.html
+│   ├── css/
+│   │   └── styles.css
+│   ├── js/
+│   │   ├── app.js
+│   │   ├── api.js
+│   │   └── components/
+│   └── assets/
+├── docker-compose.yml
+└── readme.md
+```
+
+### 1.2 Database Schema Design
+**Core entities:**
+- **users** - User accounts (id, username, email, password_hash, created_at)
+- **exercises** - Exercise definitions (id, name, type, muscle_group, description)
+- **training_plans** - Training plan templates (id, user_id, name, description)
+- **plan_exercises** - Exercises in a plan (id, plan_id, exercise_id, sets, reps, duration, order)
+- **sessions** - Completed training sessions (id, user_id, plan_id, date, notes)
+- **session_entries** - Individual exercise entries (id, session_id, exercise_id, weight, reps, duration, sets_completed)
+
+**Choice:** PostgreSQL (can use Docker for local development)
+
+---
+
+## Phase 2: Backend Development (Golang)
+
+### 2.1 Initial Setup
+- Initialize Go module
+- Set up HTTP router (standard library `net/http` or `chi`/`gorilla/mux`)
+- Configure environment variables
+- Set up database connection
+
+### 2.2 API Endpoints
+```
+# Auth endpoints (deferred to v2)
+# POST   /api/auth/register
+# POST   /api/auth/login
+
+Exercises:
+  GET    /api/exercises          # List all exercises
+  POST   /api/exercises          # Create exercise
+  GET    /api/exercises/:id      # Get exercise
+  PUT    /api/exercises/:id      # Update exercise
+  DELETE /api/exercises/:id      # Delete exercise
+
+Training Plans:
+  GET    /api/plans              # List user's plans
+  POST   /api/plans              # Create plan
+  GET    /api/plans/:id          # Get plan with exercises
+  PUT    /api/plans/:id          # Update plan
+  DELETE /api/plans/:id          # Delete plan
+
+Sessions:
+  GET    /api/sessions           # List sessions (with filters)
+  POST   /api/sessions           # Create/start session
+  GET    /api/sessions/:id       # Get session details
+  PUT    /api/sessions/:id       # Update session
+  DELETE /api/sessions/:id       # Delete session
+  POST   /api/sessions/:id/entries  # Add entry to session
+```
+
+### 2.3 Core Backend Tasks
+1. Set up Go project structure and dependencies
+2. Set up PostgreSQL via Docker
+3. Implement database migrations
+4. Create data models and repository layer
+5. Implement REST API handlers
+6. Add input validation and error handling
+7. Implement CORS for frontend communication
+8. (v2) Add authentication
+
+---
+
+## Phase 3: Frontend Development (HTML/CSS/JS)
+
+### 3.1 Mobile-First Design
+- Responsive CSS with mobile breakpoints
+- Touch-friendly UI elements
+- Offline-capable design (future PWA)
+
+### 3.2 Core Views/Pages
+1. **Dashboard** - Overview of recent sessions, quick actions
+2. **Training Plan View** - Display exercises for current session
+3. **Session Logger** - Form to enter weights/reps/duration during workout
+   - Strength: weight, sets, reps
+   - Cardio: duration, distance, heart rate (optional)
+4. **History** - View past sessions and progress
+5. **Exercise Library** - Browse and manage exercises
+6. (v2) **Login/Register** - Authentication screens
+
+### 3.3 Frontend Tasks
+1. Create base HTML structure and navigation
+2. Implement responsive CSS (flexbox/grid)
+3. Build API client module (fetch wrapper)
+4. Create reusable UI components
+5. Implement session logging interface
+6. Add form validation
+7. Implement local storage for offline data entry
+
+---
+
+## Phase 4: Integration & Testing
+
+### 4.1 Integration
+- Connect frontend to backend API
+- Test all CRUD operations
+- Handle loading states and errors
+- Implement authentication flow
+
+### 4.2 Testing
+- Backend: Unit tests for handlers and services
+- Frontend: Manual testing on mobile devices
+- API: Integration tests
+
+---
+
+## Phase 5: Deployment (Optional for v1)
+
+- Docker containerization
+- Docker Compose for local development
+- Basic deployment documentation
+
+---
+
+## Future Enhancements (v2+)
+- Strava integration
+- Whoop integration
+- Progress charts and analytics
+- Workout timer
+- PWA with offline support
+- Export data (CSV/PDF)
+
+---
+
+## Recommended Implementation Order
+
+1. **Backend foundation** - Go project setup, PostgreSQL via Docker, basic models
+2. **Core API** - Exercises and sessions endpoints (strength + cardio support)
+3. **Frontend skeleton** - HTML structure, CSS, navigation
+4. **Session logging** - The core feature (enter workout data)
+5. **Training plans** - Plan viewing and management
+6. **Polish** - Error handling, validation, UX improvements
+7. (v2) **Authentication** - User accounts
+
+---
+
+## Decisions Made
+
+- **Database**: PostgreSQL (via Docker for local dev)
+- **Authentication**: None initially (single-user mode), add in v2
+- **Exercise types**: Both strength (weight/sets/reps) and cardio (duration/distance/HR)
+
+## Verification
+
+After implementation, verify by:
+1. Start PostgreSQL container and backend server
+2. Open frontend in browser (mobile viewport)
+3. Create a test exercise (e.g., "Bench Press" - strength type)
+4. Create a training plan with exercises
+5. Log a session with actual data entry
+6. View session history
--- a/plans/testing-plan.md
+++ b/plans/testing-plan.md
@@ -0,0 +1,152 @@
+# Backend Testing Plan
+
+## Overview
+
+Add comprehensive tests for the training-tracker backend following Go best practices and the CLAUDE.md guidelines (table-driven tests).
+
+**Scope:** Both unit tests (handlers with mocks) AND integration tests (repositories with testcontainers)
+
+**Plan storage:** Copy this plan to `training-tracker/plans/testing-plan.md`
+
+## Current State
+
+- **No existing tests** - greenfield testing
+- 3 packages to test: `api`, `storage`, `models`
+- Dependencies: handlers → repositories → database
+
+## Testing Strategy
+
+### 1. Unit Tests for API Handlers
+
+Test HTTP handlers with mocked repositories.
+
+**Files to create:**
+- `internal/api/exercises_test.go`
+- `internal/api/plans_test.go`
+- `internal/api/sessions_test.go`
+
+**Approach:**
+- Define repository interfaces
+- Create mock implementations
+- Use `httptest.NewRecorder()` and `httptest.NewRequest()`
+- Table-driven tests for each endpoint
+
+**Test cases per handler:**
+- List: empty result, multiple results
+- GetByID: found, not found
+- Create: valid input, missing required fields, invalid type
+- Update: found, not found, validation errors
+- Delete: found, not found
+
+### 2. Integration Tests for Storage Layer
+
+Test repositories against real PostgreSQL using testcontainers.
+
+**Files to create:**
+- `internal/storage/exercises_test.go`
+- `internal/storage/plans_test.go`
+- `internal/storage/sessions_test.go`
+- `internal/storage/db_test.go`
+
+**Approach:**
+- Use `testcontainers-go` to spin up PostgreSQL
+- Run migrations before tests
+- Test CRUD operations end-to-end
+- Test transaction rollback scenarios
+
+**Test cases:**
+- CRUD operations for each entity
+- Cascading deletes
+- Transaction handling in plans (create/update)
+- NULL field handling
+- Foreign key constraints
+
+### 3. Test File Structure
+
+```
+backend/internal/
+├── api/
+│   ├── exercises_test.go
+│   ├── plans_test.go
+│   ├── sessions_test.go
+│   └── mocks_test.go        # Shared mock implementations
+├── storage/
+│   ├── testhelpers_test.go  # Shared test database setup
+│   ├── exercises_test.go
+│   ├── plans_test.go
+│   └── sessions_test.go
+└── models/
+    └── (no tests needed - pure data structures)
+```
+
+## Implementation Steps
+
+1. **Create plans folder** and store this plan:
+   - Create `training-tracker/plans/`
+   - Copy this plan to `training-tracker/plans/testing-plan.md`
+
+2. **Add test dependencies** to go.mod:
+   - `github.com/testcontainers/testcontainers-go`
+   - Use standard library for assertions (no testify)
+
+3. **Create repository interfaces** in `internal/api/`:
+   - `ExerciseRepository` interface
+   - `PlanRepository` interface
+   - `SessionRepository` interface
+
+4. **Create mock implementations** for unit testing handlers
+
+5. **Create test helpers** for integration tests:
+   - Shared PostgreSQL container setup
+   - Database cleanup between tests
+
+6. **Write handler unit tests** (table-driven):
+   - All CRUD operations
+   - Validation error paths
+   - Not found scenarios
+
+7. **Write storage integration tests** (table-driven):
+   - All repository methods
+   - Edge cases and error conditions
+
+8. **Update CLAUDE.md** with testing instructions
+
+## Files to Modify
+
+- `backend/go.mod` - add test dependencies
+- `backend/internal/api/router.go` - extract interfaces for testability
+- `backend/CLAUDE.md` - add testing instructions
+
+## Files to Create
+
+- `plans/testing-plan.md` - this plan document
+- `backend/internal/api/interfaces.go` - repository interfaces
+- `backend/internal/api/mocks_test.go` - mock implementations
+- `backend/internal/api/exercises_test.go`
+- `backend/internal/api/plans_test.go`
+- `backend/internal/api/sessions_test.go`
+- `backend/internal/storage/testhelpers_test.go`
+- `backend/internal/storage/exercises_test.go`
+- `backend/internal/storage/plans_test.go`
+- `backend/internal/storage/sessions_test.go`
+
+## Verification
+
+```bash
+cd backend
+
+# Run all tests
+go test ./...
+
+# Run with verbose output
+go test -v ./...
+
+# Run with coverage
+go test -cover ./...
+
+# Run only unit tests (fast)
+go test -short ./...
+
+# Run specific package
+go test -v ./internal/api/...
+```
--- a/project.md
+++ b/project.md
@@ -0,0 +1,13 @@
+# Training tracker
+
+Will be application for tracking my activities relevant to training.
+It will have:
+- frontend: 
+    - mobile friendly web application which is gonna let me view training plan for the session, will allow to enter session type, weights/resistance, repetitions, duration or other relevant attributes of the session.
+    - technologies to be used: html, css, javascript
+- backend:
+    - service written in golang available over http/https allowing frontend to access/persist all the necessary information
+    - persistent layer will ba suitable database, either sql or nosql
+- auxiliary services:
+    - this is something extra which does not have to be part of 1st version of the app and will be able to read data from strava or whoop
+