refactor: change from standar backend api to python library

AGENTS.md

@@ -1,38 +1,30 @@
 # AGENTS.md
 
-This project is a FastAPI backend for generating structured math problems. The intended design should scale to grades 1 through 6 and multiple problem types per grade.
+This project is a Python library for generating structured math problems. The intended design should scale to grades 1 through 6 and multiple problem types per grade.
 
 ## Run And Test
 
-- Start the API with `uv run uvicorn main:app --reload`.
-- Open API docs at `http://127.0.0.1:8000/docs`.
 - Run tests with `uv run python -m unittest`.
 - Compile changed Python files with `uv run python -m py_compile <files>`.
+- Run the usage example with `uv run python test.py`.
 
-## Endpoint example
+## Usage example
 
-- `POST /math/grade_1/join_pictures_with_quantity`
-- The caller sends image metadata and optional generation settings.
-- The endpoint returns a JSON-ready math problem where students count images and match groups to numbers.
+- `from math_problems_structure.grade_1 import join_pictures_with_quantity`
+- The caller passes image metadata and optional generation settings.
+- The function returns a JSON-ready math problem where students count images and match groups to numbers.
 
 ## Responsibilities
 
-- `main.py` is only the uvicorn entry point. Keep it thin.
-- `app/main.py` defines `create_app()` and includes the top-level API router.
-- `app/routers/math.py` owns the `/math` router and includes grade routers.
-- `app/routers/grade_1.py` registers all grade 1 HTTP endpoints.
+- `app/__init__.py` exposes the public library functions.
 - `app/problems/grade_1/` contains reusable generation logic for grade 1 problems.
 - `app/schemas/grade_1/` contains Pydantic request/response models for grade 1 problems.
-- `tests/` contains endpoint tests using `fastapi.testclient.TestClient`.
+- `tests/` contains direct function tests.
 
 ## Design Rules
 
-- Keep HTTP code in `app/routers/`.
 - Keep generation logic in `app/problems/`.
 - Keep all Pydantic models in `app/schemas/`.
-- Do not put generation logic in routers.
-- Do not put FastAPI router code in problem generator modules.
-- Prefer one router file per grade, not one router file per problem.
 - Prefer one schema file per problem type.
 - Prefer one generator file per problem type.
 
@@ -42,22 +34,18 @@ For a new grade 1 problem named `example_problem`:
 
 1. Add schemas in `app/schemas/grade_1/example_problem.py`.
 2. Add generator logic in `app/problems/grade_1/example_problem.py`.
-3. Register the endpoint in `app/routers/grade_1.py`.
-4. Add endpoint tests in `tests/`.
+3. Export the function from `app/problems/grade_1/__init__.py` and `app/__init__.py` if it is public.
+4. Add direct function tests in `tests/`.
 5. Run `uv run python -m unittest`.
 
 For a new grade, follow the same pattern:
 
 1. Add `app/schemas/grade_2/` and `app/problems/grade_2/`.
-2. Add `app/routers/grade_2.py`.
-3. Include the new grade router from `app/routers/math.py`.
-4. Add tests.
-
-Every time you add a new problem, also add an endpoint curl example on the ENDPOINTS-EXAMPLE.md file.
+2. Export public functions from the relevant package `__init__.py` files.
+3. Add tests.
 
 ## Naming Conventions
 
-- Endpoint paths use the existing style: `/math/grade_1/<problem_name>`.
 - Python package names should use valid identifiers like `grade_1`.
 - Problem files should use snake case, for example `join_pictures_with_quantity.py`.
 - Request schema names should end in `Request`.