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KERN’s onboarding flow is linear by design: register to get a token, complete the quiz to generate a routine, then start training. The steps below walk you through the full sequence using real API calls. Every protected endpoint requires the Authorization: Bearer <token> header returned in step 1.
All examples below target the production API hosted on Vercel. Replace the base URL with http://localhost:8002 if you are running the backend locally.
1

Register and get your access token

Send a POST /register request with your username, email, and password. The API hashes the password with SHA-256, creates a user record, and returns a signed JWT immediately — no separate login step needed.
curl --request POST \
  --url https://your-kern-api.vercel.app/register \
  --header 'Content-Type: application/json' \
  --data '{
    "username": "alex",
    "email": "alex@example.com",
    "password": "strongpassword123"
  }'
Save the accessToken value. You will pass it as a Bearer token in every subsequent request. Tokens expire after 30 minutes — call POST /login with your email and password to refresh.
If the username or email is already taken, the API returns HTTP 400 with "El usuario o email ya existe".
2

Complete the fitness quiz

Send a POST /users/complete-quiz with your chosen routine type. This sets has_completed_quiz to true on your user record and triggers automatic routine generation: the backend reads ROUTINE_CONFIGS for the selected type, queries exercises_gym_id.json to select one exercise per movement pattern, and writes RoutineExercise rows to the database.Available routine values:
ValueExercises generated
"Full Body"5 exercises — horizontal push, vertical pull, squat, vertical push, hip hinge
"PPL (Push Pull Leg)"8 exercises — chest, upper chest, shoulders, back (vertical + horizontal), biceps, quads, hamstrings
"Torso-Pierna"6 exercises — chest (two patterns), back (two patterns), squat, hip hinge
curl --request POST \
  --url https://your-kern-api.vercel.app/users/complete-quiz \
  --header 'Authorization: Bearer eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9...' \
  --header 'Content-Type: application/json' \
  --data '{
    "assigned_routine": "Full Body"
  }'
The assigned_routine string must match one of the three values exactly, including capitalisation and parentheses. An unrecognised value is saved to the user record but no exercises will be generated.
3

Fetch your generated routine

Retrieve all routines for the authenticated user with GET /users/my-routines. The response is an array of routine objects, each containing its id, name, creation timestamp, and a list of exercises with their default series (three sets at 0 kg × 10 reps).
curl --request GET \
  --url https://your-kern-api.vercel.app/users/my-routines \
  --header 'Authorization: Bearer eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9...'
Note the routine id — you will use it to start a workout in the next step.
4

Start a workout and view historical suggestions

Before recording a session, fetch the detailed routine view with GET /routines/{id}. This endpoint enriches each series with data from your most recent WorkoutSession for that routine: prev_kilos and prev_reps are numeric values for pre-filling input fields; anterior is a human-readable string (e.g. "60.0kg x 8") shown as a visual suggestion.
curl --request GET \
  --url https://your-kern-api.vercel.app/routines/7 \
  --header 'Authorization: Bearer eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9...'
On your very first session there is no history yet, so anterior will be "--" and both prev_kilos and prev_reps will be 0. Complete the workout to establish your baseline for next time.
5

Finish the workout and save your session

When all exercises are done, send POST /workouts/finish. Include the routine name, duration in seconds, total volume (kilograms × repetitions summed across all completed sets), step count recorded by the device sensor, and a data_json snapshot of every exercise and series.The data_json array becomes the source of truth for prev_kilos and prev_reps in all future sessions for this routine.
curl --request POST \
  --url https://your-kern-api.vercel.app/workouts/finish \
  --header 'Authorization: Bearer eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9...' \
  --header 'Content-Type: application/json' \
  --data '{
    "routine_name": "Mi Rutina Full Body Inicial",
    "duration_seconds": 3600,
    "total_volume": 4200.0,
    "steps": 812,
    "data_json": [
      {
        "name": "Bench Press",
        "series": [
          { "numSerie": 1, "kilos": 60.0, "reps": 8 },
          { "numSerie": 2, "kilos": 62.5, "reps": 7 },
          { "numSerie": 3, "kilos": 62.5, "reps": 6 }
        ]
      },
      {
        "name": "Pull-Up",
        "series": [
          { "numSerie": 1, "kilos": 0.0, "reps": 10 },
          { "numSerie": 2, "kilos": 0.0, "reps": 9 },
          { "numSerie": 3, "kilos": 0.0, "reps": 8 }
        ]
      }
    ]
  }'
The session is now saved to workout_sessions. The next time you call GET /routines/7, each series will reflect the kilos and reps you just submitted.

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What’s next

Architecture

Understand how the FastAPI backend, Android client, and PostgreSQL schema fit together.

API reference

Full endpoint documentation including avatar updates, username changes, and workout history.

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