Extract Model CRUD out of the crud/__init__.py monolith

[akwasigroch]

Purpose

crud/__init__.py is a 1946-line monolith that the codebase is splitting one entity at a time, following #2411, #2412, #2438, #2439, #2441, #2442, #2449, #2450 and #2451. This takes the Model block out. Per apps/backend/AGENTS.md the package only shrinks from here — nothing new goes back into __init__.py.

What Changed

• Moved get_model, get_models, create_model, update_model and delete_model into a new crud/model.py (149 lines), byte-for-byte. The internal coupling stays inside the new module: update_model and delete_model both call get_model.
• crud/__init__.py drops 142 lines. The Tool block directly below is untouched.
• Nothing is re-exported, matching the earlier splits. All 25 call sites across 13 files now use from rhesis.backend.app.crud import model as model_crud. The alias matters here — many of these modules already import models, and model/models is easy to confuse.
• Dropped test_model_connection. Zero callers repo-wide. The /models/{id}/test endpoint has its own async test_model_connection in routers/model.py backed by ModelConnectionService; the crud version was a stub whose entire body was return True inside a try that could never raise. Dead code that read as live because a real function shares its name.
• The module docstring records the is_protected system-model rules, since they are enforced across two functions and are easy to miss: protected models reject edits to name, model_name, provider_type_id, key, endpoint, is_protected and icon, and reject deletion outright, while tags, status, owner and assignee stay editable.

Additional Context

• One of four parallel extractions: Behavior (Extract Behavior CRUD out of the crud/__init__.py monolith #2455), File (Extract File CRUD out of the crud/__init__.py monolith #2456), Model and User (Extract User CRUD out of the crud/__init__.py monolith #2458). The four blocks were chosen so they do not touch each other in crud/__init__.py, and git merge-tree confirms __init__.py merges clean across all six pairings.
• This branch conflicts with Behavior in services/test_config_generator.py and services/test_generation_pipeline.py, and with User in services/explorer/embeddings.py and utils/user_model_utils.py. All four are the same trivial shape — each branch inserts its own crud submodule import at the same spot, so the resolution is to keep both lines. Once each pair lands, the last bare crud. use disappears from that file and the from rhesis.backend.app import crud import must be dropped (ruff F401).
• Suggested landing order across the four: Behavior and File first (conflict-free), then this one, then User.
• Deliberately avoids get_test_sets and get_tests, which Add metric tuning for custom metrics [feature branch] #2446 modifies. Kept as a pure move so Rename Rhesis Default model to Rhesis #2385 (Rhesis Default model rename) rebases cleanly.

Testing

Pure move plus one dead-function deletion, so the existing suite is the check.

cd apps/backend
uv run pytest ../../tests/backend/routes/test_model.py ../../tests/backend/utils/test_llm_delegation.py ../../tests/backend/security/test_organization_filtering.py
# 70 passed

uv run pytest ../../tests/backend/crud ../../tests/backend/security ../../tests/backend/utils ../../tests/backend/services
# 3237 passed, 4 skipped, 1 xfailed

uv run pytest ../../tests/backend/routes ../../tests/backend/app ../../tests/backend/metrics
# 1823 passed, 40 skipped

Ruff clean on all 13 touched files. A repo-wide grep for the six old crud.* names returns nothing.

Two things worth a reviewer's eye:

routers/services.py was already using the name model_crud, but bound to the whole crud package rather than a submodule — exactly the reach-through pattern apps/backend/AGENTS.md warns about, which only worked because the alias happened to resolve get_model off the monolith. It now points at the real submodule.

get_model collides three ways in this area: this crud function, the SDK factory rhesis.sdk.models.factory.get_model, and the router endpoint. utils/user_model_utils.py imports both the SDK factory and model_crud, and tests/backend/utils/test_llm_delegation.py deliberately patches both ...user_model_utils.get_model (SDK) and ...user_model_utils.model_crud.get_model (crud).

[peqy]

Looks good. Clean extraction of the model CRUD into crud/model.py with call sites updated consistently, and dropping the unused test_model_connection stub reduces misleading surface area. Ship it.

[peqy]

Looks good. The Model CRUD was cleanly extracted into crud/model.py, call sites were updated consistently, and removing the unused test_model_connection stub reduces misleading surface area. Ship it.